Science.gov

Sample records for disc replacement pitfalls

  1. Artificial Disc Replacement

    MedlinePlus

    ... treat this condition, alternatives to disc replacement include fusion, nonoperative care or no treatment. Typically, surgery is ... operative treatment for disc pain has been spinal fusion. This is a surgical procedure in which disc ...

  2. Artificial Disc Replacement

    MedlinePlus

    ... also disc replacements designed for use in the cervical spine (the neck). These devices have only been used ... of your spine increases the risk of significant injury during this type of spinal surgery. Back pain ...

  3. Total disc replacement.

    PubMed

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  4. Reoperations Following Cervical Disc Replacement

    PubMed Central

    Skovrlj, Branko; Lee, Dong-Ho; Caridi, John Michael

    2015-01-01

    Cervical disc replacement (CDR) has emerged as an alternative surgical option to cervical arthrodesis. With increasing numbers of patients and longer follow-ups, complications related to the device and/or aging spine are growing, leaving us with a new challenge in the management and surgical revision of CDR. The purpose of this study is to review the current literature regarding reoperations following CDR and to discuss about the approaches and solutions for the current and future potential complications associated with CDR. The published rates of reoperation (mean, 1.0%; range, 0%-3.1%), revision (mean, 0.2%; range, 0%-0.5%), and removal (mean, 1.2%; range, 0%-1.9%) following CDR are low and comparable to the published rates of reoperation (mean, 1.7%; range; 0%-3.4%), revision (mean, 1.5%; range, 0%-4.7%), and removal (mean, 2.0%; range, 0%-3.4%) following cervical arthrodesis. The surgical interventions following CDR range from the repositioning to explantation followed by fusion or the reimplantation to posterior foraminotomy or fusion. Strict patient selection, careful preoperative radiographic review and surgical planning, as well as surgical technique may reduce adverse events and the need for future intervention. Minimal literature and no guidelines exist for the approaches and techniques in revision and for the removal of implants following CDR. Adherence to strict indications and precise surgical technique may reduce the number of reoperations, revisions, and removals following CDR. Long-term follow-up studies are needed, assessing the implant survivorship and its effect on the revision and removal rates. PMID:26097667

  5. Intervertebral disc replacement. Experimental study.

    PubMed

    Kostuik, J P

    1997-04-01

    Arthrodesis of the lumbosacral spine, although satisfactory for a majority of patients, has long term sequelae in 30% of patients. This is particularly true for adjacent segment degeneration. Numerous attempts at providing a mobile motion segment have been made in the past. The current status of the development of dynamic intervertebral prosthesis, including biomechanical and clinical data have been presented. The relevant material properties of plastics, ceramics, and metal are presented with the conclusion that metals currently present with the greatest longevity without undue fatigue and wear as many as 100,000,000 cycles (40 years use) as an alternative to spinal fusion. An analysis of the kinematics of the motion segment have resulted, together with the material properties in the development of a dynamic intervertebral disc for use in the lumbar spine. The disc resembles a normal motion segment. In motion stiffness and center of rotation, wear debris development in 1/300 equivalent to that of a total hip prosthesis for the same given time. Safety features include immediate screw fixation to prevent displacement, a wedge elastic (spring) shape, and a bony porous ingrowth surface. The prosthesis is constructed of cobalt chromium and titanium with minimal corrosive properties on long term testing.

  6. Material considerations for intervertebral disc replacement implants.

    PubMed

    Taksali, Sudeep; Grauer, Jonathan N; Vaccaro, Alexander R

    2004-01-01

    Cervical and lumbar disc replacements are being performed with increasing frequency. Much of the background for the development for these implants is drawn from the literature of other joint replacements that have been in evolution and use for decades. Important variables for the function and longevity of such disc arthroplasty implants are clearly defined by the material properties of the components used for their production. The most frequently considered materials are cobalt-chrome alloys, titanium alloys, stainless steels, polyethylene, polyurethane and ceramics. In addition to implant materials, the interfaces of such materials must be considered. The bearing surfaces of an implant, in particular, are at risk of wear and failure. Overall, successful, long-term total disc arthroplasty requires a thorough understanding of biomaterials and how they can be used to achieve their desired goals.

  7. Total Disc Replacement in Lumbar Degenerative Disc Diseases

    PubMed Central

    2015-01-01

    More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above. PMID:26713139

  8. Material Science in Cervical Total Disc Replacement

    PubMed Central

    Pham, Martin H.; Mehta, Vivek A.; Tuchman, Alexander; Hsieh, Patrick C.

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281

  9. Material Science in Cervical Total Disc Replacement.

    PubMed

    Pham, Martin H; Mehta, Vivek A; Tuchman, Alexander; Hsieh, Patrick C

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation.

  10. Autologous adipose stem cells and polylactide discs in the replacement of the rabbit temporomandibular joint disc

    PubMed Central

    Ahtiainen, Katja; Mauno, Jari; Ellä, Ville; Hagström, Jaana; Lindqvist, Christian; Miettinen, Susanna; Ylikomi, Timo; Kellomäki, Minna; Seppänen, Riitta

    2013-01-01

    The temporomandibular joint (TMJ) disc lacks functional replacement after discectomy. We investigated tissue-engineered bilayer polylactide (PLA) discs and autologous adipose stem cells (ASCs) as a potential replacement for the TMJ disc. These ASC discs were pre-cultured either in control or in differentiation medium, including transforming growth factor (TGF)-β1 for one week. Prior to implantation, expression of fibrocartilaginous genes was measured by qRT-PCR. The control and differentiated ASC discs were implanted, respectively, in the right and left TMJs of rabbits for six (n = 5) and 12 months (n = 5). Thereafter, the excised TMJ areas were examined with cone beam computed tomography (CBCT) and histology. No signs of infection, inflammation or foreign body reactions were detected at histology, whereas chronic arthrosis and considerable condylar hypertrophy were observed in all operated joints at CBCT. The left condyle treated with the differentiated ASC discs appeared consistently smoother and more sclerotic than the right condyle. The ASC disc replacement resulted in dislocation and morphological changes in the rabbit TMJ. The ASC discs pre-treated with TGF-β1 enhanced the condylar integrity. While adverse tissue reactions were not shown, the authors suggest that with improved attachment and design, the PLA disc and biomaterial itself would hold potential for TMJ disc replacement. PMID:23720535

  11. Autologous adipose stem cells and polylactide discs in the replacement of the rabbit temporomandibular joint disc.

    PubMed

    Ahtiainen, Katja; Mauno, Jari; Ellä, Ville; Hagström, Jaana; Lindqvist, Christian; Miettinen, Susanna; Ylikomi, Timo; Kellomäki, Minna; Seppänen, Riitta

    2013-08-06

    The temporomandibular joint (TMJ) disc lacks functional replacement after discectomy. We investigated tissue-engineered bilayer polylactide (PLA) discs and autologous adipose stem cells (ASCs) as a potential replacement for the TMJ disc. These ASC discs were pre-cultured either in control or in differentiation medium, including transforming growth factor (TGF)-β1 for one week. Prior to implantation, expression of fibrocartilaginous genes was measured by qRT-PCR. The control and differentiated ASC discs were implanted, respectively, in the right and left TMJs of rabbits for six (n = 5) and 12 months (n = 5). Thereafter, the excised TMJ areas were examined with cone beam computed tomography (CBCT) and histology. No signs of infection, inflammation or foreign body reactions were detected at histology, whereas chronic arthrosis and considerable condylar hypertrophy were observed in all operated joints at CBCT. The left condyle treated with the differentiated ASC discs appeared consistently smoother and more sclerotic than the right condyle. The ASC disc replacement resulted in dislocation and morphological changes in the rabbit TMJ. The ASC discs pre-treated with TGF-β1 enhanced the condylar integrity. While adverse tissue reactions were not shown, the authors suggest that with improved attachment and design, the PLA disc and biomaterial itself would hold potential for TMJ disc replacement.

  12. In vitro and in silico investigations of disc nucleus replacement

    PubMed Central

    Reitmaier, Sandra; Shirazi-Adl, Aboulfazl; Bashkuev, Maxim; Wilke, Hans-Joachim; Gloria, Antonio; Schmidt, Hendrik

    2012-01-01

    Currently, numerous hydrogels are under examination as potential nucleus replacements. The clinical success, however, depends on how well the mechanical function of the host structure is restored. This study aimed to evaluate the extent to and mechanisms by which surgery for nucleus replacements influence the mechanical behaviour of the disc. The effects of an annulus defect with and without nucleus replacement on disc height and nucleus pressure were measured using 24 ovine motion segments. The following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue repaired by suture and glue or plug. To identify the likely mechanisms observed in vitro, a finite-element model of a human disc (L4–L5) was employed. Both studies were subjected to physiological cycles of compression and recovery. A repaired annulus defect did not influence the disc behaviour in vitro, whereas additional nucleus removal and replacement substantially decreased disc stiffness and nucleus pressure. Model predictions demonstrated the substantial effects of reductions in replaced nucleus water content, bulk modulus and osmotic potential on disc height loss and pressure, similar to measurements. In these events, the compression load transfer in the disc markedly altered by substantially increasing the load on the annulus when compared with the nucleus. The success of hydrogels for nucleus replacements is not only dependent on the implant material itself but also on the restoration of the environment perturbed during surgery. The substantial effects on the disc response of disruptions owing to nucleus replacements can be simulated by reduced nucleus water content, elastic modulus and osmotic potential. PMID:22337630

  13. In vitro and in silico investigations of disc nucleus replacement.

    PubMed

    Reitmaier, Sandra; Shirazi-Adl, Aboulfazl; Bashkuev, Maxim; Wilke, Hans-Joachim; Gloria, Antonio; Schmidt, Hendrik

    2012-08-07

    Currently, numerous hydrogels are under examination as potential nucleus replacements. The clinical success, however, depends on how well the mechanical function of the host structure is restored. This study aimed to evaluate the extent to and mechanisms by which surgery for nucleus replacements influence the mechanical behaviour of the disc. The effects of an annulus defect with and without nucleus replacement on disc height and nucleus pressure were measured using 24 ovine motion segments. The following cases were considered: intact; annulus incision repaired by suture and glue; annulus incision with removal and re-implantation of nucleus tissue repaired by suture and glue or plug. To identify the likely mechanisms observed in vitro, a finite-element model of a human disc (L4-L5) was employed. Both studies were subjected to physiological cycles of compression and recovery. A repaired annulus defect did not influence the disc behaviour in vitro, whereas additional nucleus removal and replacement substantially decreased disc stiffness and nucleus pressure. Model predictions demonstrated the substantial effects of reductions in replaced nucleus water content, bulk modulus and osmotic potential on disc height loss and pressure, similar to measurements. In these events, the compression load transfer in the disc markedly altered by substantially increasing the load on the annulus when compared with the nucleus. The success of hydrogels for nucleus replacements is not only dependent on the implant material itself but also on the restoration of the environment perturbed during surgery. The substantial effects on the disc response of disruptions owing to nucleus replacements can be simulated by reduced nucleus water content, elastic modulus and osmotic potential.

  14. Bryan total disc arthroplasty: a replacement disc for cervical disc disease

    PubMed Central

    Wenger, Markus; Markwalder, Thomas-Marc

    2010-01-01

    Total disc arthroplasty is a new option in the treatment of cervical degenerative disc disease. Several types of cervical disc prostheses currently challenge the gold-standard discectomy and fusion procedures. This review describes the Bryan Cervical Disc System and presents the Bryan prosthesis, its indications, surgical technique, complications, and outcomes, as given in the literature. PMID:22915917

  15. Pitfalls

    NASA Technical Reports Server (NTRS)

    Triffet, Terry

    1990-01-01

    Though potentially of great benefit to the nation, the experience of the workshop participants and their discussions with Sea Grant and Land Grant officials make it clear that the Space Grant Program must avoid certain pitfalls of the past and present if it is to be successful. The most important of these are listed and briefly discussed.

  16. Preclinical and clinical experience with a viscoelastic total disc replacement

    PubMed Central

    Rischke, Burkhard; Ross, Raymond S.; Jollenbeck, Boris A.; Zimmers, Kari B.; Defibaugh, Neal D.

    2011-01-01

    Background The purpose of this study is to describe the mechanical durability and the clinical and radiographic outcomes of a viscoelastic total disc replacement (VTDR). The human intervertebral disc is a complex, viscoelastic structure, permitting and constraining motion in 3 axes, thus providing stability. The ideal disc replacement should be viscoelastic and deformable in all directions, and it should restore disc height and angle. Methods Mechanical testing was conducted to validate the durability of the VTDR, and a clinical study was conducted to evaluate safety and performance. Fifty patients with single-level, symptomatic lumbar degenerative disc disease at L4-5 or L5-S1 were enrolled in a clinical trial at 3 European sites. Patients were assessed clinically and radiographically for 2 years by the Oswestry Disability Index (ODI), a visual analog scale (VAS), and independent radiographic analyses. Results The VTDR showed a fatigue life in excess of 50 million cycles (50-year equivalent) and a physiologically appropriate level of stiffness, motion, geometry, and viscoelasticity. We enrolled 28 men and 22 women in the clinical study, with a mean age of 40 years. Independent quantitative radiographic assessment indicated that the VTDR restored and maintained disc height and lordosis while providing physiologic motion. Mean ODI scores decreased from 48% preoperatively to 23% at 2 years’ follow-up. Mean VAS low-back pain scores decreased from 7.1 cm to 2.9 cm. Median scores indicated that half of the patient population had ODI scores below 10% and VAS low-back pain scores below 0.95 cm at 2 years. Conclusions The VTDR has excellent durability and performs clinically and radiographically as intended for the treatment of symptomatic lumbar degenerative disc disease. Clinical Relevance The VTDR is intended to restore healthy anatomic properties and stability characteristics to the spinal segment. This study is the first to evaluate a VTDR in a 50-patient

  17. [Infants of drug-addicted mothers: pitfalls of replacement therapy].

    PubMed

    Vert, Paul; Hamon, Isabelle; Hubert, Claire; Legagneur, Michel; Hascoet, Jean-Michel

    2008-05-01

    Maternal drug addiction can cause problems for the fetus and the newborn, and hamper long-term development. The prevalence of drug addiction during pregnancy varies from 1 % to more than 10 % depending on the country and the maternity unit. Management of these mothers can be further complicated by medical, social and psychological problems. Compared to methadone, heroin replacement therapy with buprenorphine provides better stabilization of the mother and causes fewer withdrawal symptoms in the newborn. Despite numerous publications on the effects of this partly preventive medication, data on buprenorphine pharmacology at birth are scarce. In this study, 20 newborns of mothers using oral buprenorphine were observed until the end of the withdrawal syndrome, when present. Buprenorphine plasma levels were determined with HPLC and mass spectrometry in the mother at delivery and in the newborn at birth (cord blood), 24 and 48 hours. Fifteen newborns were born at term (mean +/- SD birth weight 3029 +/- 273 g), and the other five between 32 and 36 weeks. All Apgar scores were > or =7. Withdrawal symptoms were observed in 8 of the 15 infants born to mothers taking buprenorphine alone, and lasted between 5 and 35 days. The newborns were classified in three groups. Groups I (N8) and II (N7) comprised newborns with and without withdrawal symptoms, respectively. In group III (N5), the mothers were polyintoxicated (as shown by urinary drug or neurotropic substance screening) and the newborns were symptomatic for 1 to 69 days. Buprenorphine plasma levels in the mothers ranged from 0 to 2.9 microg/L, suggesting large differences in adherence. At birth there was no significant difference in the mean plasma buprenorphine level between newborns with and without withdrawal symptoms; the respective values were 0.7 (0.4-1.3) and 0.5 (0-0.6) microg/L. In asymptomatic newborns (group II), buprenorphine was no longer detectable at 48 h, whereas in symptomatic newborns (group I), the mean

  18. Total disc replacement surgery for symptomatic degenerative lumbar disc disease: a systematic review of the literature

    PubMed Central

    van den Eerenbeemt, Karin D.; van Royen, Barend J.; Peul, Wilco C.; van Tulder, Maurits W.

    2010-01-01

    The objective of this study is to evaluate the effectiveness and safety of total disc replacement surgery compared with spinal fusion in patients with symptomatic lumbar disc degeneration. Low back pain (LBP), a major health problem in Western countries, can be caused by a variety of pathologies, one of which is degenerative disc disease (DDD). When conservative treatment fails, surgery might be considered. For a long time, lumbar fusion has been the “gold standard” of surgical treatment for DDD. Total disc replacement (TDR) has increased in popularity as an alternative for lumbar fusion. A comprehensive systematic literature search was performed up to October 2008. Two reviewers independently checked all retrieved titles and abstracts, and relevant full text articles for inclusion. Two reviewers independently assessed the risk of bias of included studies and extracted relevant data and outcomes. Three randomized controlled trials and 16 prospective cohort studies were identified. In all three trials, the total disc replacement was compared with lumbar fusion techniques. The Charité trial (designed as a non-inferiority trail) was considered to have a low risk of bias for the 2-year follow up, but a high risk of bias for the 5-year follow up. The Charité artificial disc was non-inferior to the BAK® Interbody Fusion System on a composite outcome of “clinical success” (57.1 vs. 46.5%, for the 2-year follow up; 57.8 vs. 51.2% for the 5-year follow up). There were no statistically significant differences in mean pain and physical function scores. The Prodisc artificial disc (also designed as a non-inferiority trail) was found to be statistically significant more effective when compared with the lumbar circumferential fusion on the composite outcome of “clinical success” (53.4 vs. 40.8%), but the risk of bias of this study was high. Moreover, there were no statistically significant differences in mean pain and physical function scores. The Flexicore trial

  19. Return to Sports After Cervical Total Disc Replacement.

    PubMed

    Reinke, Andreas; Behr, Michael; Preuss, Alexander; Villard, Jimmy; Meyer, Bernhard; Ringel, Florian

    2017-01-01

    Total disc replacement (TDR) is typically indicated in young patients with a cervical soft disc herniation. There are few data on the activity level of patients after cervical TDR, in particular from young patients who are expected to have a high activity level with frequent exercising. The expectation is that returning to active sports after cervical TDR is not restricted. Fifty patients were treated with a monosegmental cervical TDR at our department between May 2006 and March 2012. Clinical status and radiographic parameters were evaluated preoperatively and during follow-up. In addition, information was gathered regarding neck disability index, pain, a questionnaire concerning athletic aspects, and a modified Tegner activity score. The study design was a prospective case series. All patients were treated with the Prestige artificial cervical disc for a single-level soft disc herniation with radiculopathy. The average age was 40 years, and the mean follow-up period was 53 months (range, 26-96). The median neck disability index during follow-up was 5, and median visual analog scale for pain was 2. Two professional athletes, 20 semiprofessionals, 24 hobby athletes, and 5 patients with a very low activity level were treated. The median time to resumption of sporting activity was 4 weeks after surgery. All professionals and semiprofessionals recovered to their previous activity level. All of the 20 hobby athletes recovered to resume their sport participation. The modified Tegner preoperative score was 4 and the postoperative score was 3.5 (P = 0.806). We found that cervical TDR did not prohibit sporting activities. All patients recovered and were able to take part in their previous activities at an appropriate intensity level. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Effect of total lumbar disc replacement on lumbosacral lordosis.

    PubMed

    Kasliwal, Manish K; Deutsch, Harel

    2012-10-01

    Original article : To study effect of lumbar disc replacement on lumbosacral lordosis. There has been a growing interest in total disc replacement (TDR) for back pain with the rising concern of adjacent segment degeneration. Lumbar fusion surgery has been shown to lead to decrease in lumbar lordosis, which may account for postfusion pain resulting in less acceptable clinical outcome after successful fusion. TDR has recently emerged as an alternative treatment for back pain. There have been very few studies reporting lumbar sagittal outcome after TDR. Retrospective study of radiographic data of 17 patients who underwent TDR for single level degenerative disc disease at the author's institution was carried out. Study included measurement of preoperative and postoperative segmental and global lumbar lordosis and angle of lordosis. Patients age varied from 19 to 54 (mean, 35) years. Follow-up ranged from 12 to 24 months. TDR was performed at L4-5 level in 3 patients and L5-S1 level in 14 patients. The average values for segmental lordosis, global lordosis, and angle of lordosis at the operated level before and after surgery were 17.3, 49.7, and 8.6 degrees and 21.6, 54, and 9.5 degrees, respectively. There was a trend toward significant (P=0.02) and near significant (P=0.057) increase in segmental and global lordosis, respectively after TDR. Although prosthesis increased angle of lordosis at the level implanted in majority of the patients, the difference in preoperative and postoperative angle of lordosis was not significant (P=0.438). In addition, there was no correlation between the angle of implant of chosen and postoperative angle of lordosis at the operated level. The effect of TDR on sagittal balance appears favorable with an increase in global and segmental lumbar lordosis after single level TDR for degenerative disc disease. The degree of postoperative angle of lordosis was not affected by the angle of implant chosen at the operated level and varied

  1. [LOCATION CHANGE OF ROTATION CENTER AFTER SINGLE SEGMENTAL CERVICAL DISC REPLACEMENT WITH ProDisc-C].

    PubMed

    Lou, Jigang; Liu, Hao; Rong, Xin; Gong, Quan; Song, Yueming; Li, Tao

    2015-01-01

    To evaluate the effectiveness of the single segmental cervical disc replacement with ProDisc-C, and to explore the location change of the flexion/extension center of rotation (COR) of the target level as well as its clinical significance. Between June 2010 and February 2012, 23 patients underwent single segmental cervical disc replacement with ProDisc-C, and the clinical data were retrospectively analyzed. Of 23 patients, 9 were male, and 14 were female with the age range from 27 to 65 years (mean, 45 years), and the disease duration ranged from 10 to 84 months (mean, 25 months). There were 15 patients with radiculopathy, 5 patients with myelopathy, and 3 patients with mixed cervical spondylosis. The involved segments were C4,5 in 5 cases, C5,6 in 14 cases, and C6,7 in 4 cases. Japanese Orthopaedic Association (JOA) score and neck disability index (NDI) were adopted to evaluate the effectiveness. Preoperative and Postoperative radiographic parameters, such as cervical overall range of motion (ROM), target segmental ROM, the adjacent segmental ROM, and intervertebral height were compared. Besides, the location changes of the COR of the target level were further analyzed by the alteration of its coordinates (COR-X, COR-Y), and the relationships between the location changes of the COR and the effectiveness or the radiographic results were analyzed. All the operations were completed successfully; 1 case had hoarseness after operation, which disappeared at 3 months after operation. All cases were followed up 18.3 months on average (range, 6-36 months). There was no device migration, loosening, subsidence, or fracture at last follow-up. The JOA score increased significantly and the NDI score decreased significantly at last follow-up when compared with preoperative scores (P < 0.05). No difference was found in the cervical overall ROM, target segmental ROM, the adjacent segmental ROM, and the COR-Y of the target level between pre-operation and last follow-up (P > 0

  2. Surgical technique for revision surgery of cervical artificial disc replacements.

    PubMed

    Onken, Julia; Meyer, Bernhard; Vajkoczy, Peter

    2017-01-01

    OBJECTIVE Cervical artificial disc replacement (C-ADR) is a widely used procedure with low risk at implantation. Few cases have been reported about the surgical techniques of C-ADR revision. The authors describe their surgical experience with the explantation of a Galileo C-ADR. METHODS Revision surgery was performed in a 58-year-old patient. Patient positioning and surgical opening techniques were performed as appropriate for anterior cervical decompression. RESULTS Revision surgery via the initial anterior approach was successful following an atraumatic removal of the implant. Fusion of the C5-6 segment was performed without complications. CONCLUSIONS In general, the authors observed recurrent nerve palsy and malpositioning of the revised implant in C-ADR revision surgery. Problems with implant removal did not occur because the fusion rate was low due to the short time between initial surgery and C-ADR revision surgery. The video can be found here: https://youtu.be/32CUEDquinc .

  3. The role of lumbar disc replacement in the surgical management of low back pain.

    PubMed

    Freeman, Brian J C

    2012-01-01

    Spinal fusion has long been the standard surgical treatment for degenerative disorders of the spine, but clinical outcomes are often unpredictable. Lumbar disc replacement allows removal of the pain source while preserving motion. This article explores the role of lumbar disc replacement in the surgical management of low back pain.

  4. Wnt signaling during tooth replacement in zebrafish (Danio rerio): pitfalls and perspectives

    PubMed Central

    Huysseune, Ann; Soenens, Mieke; Elderweirdt, Fien

    2014-01-01

    The canonical (β-catenin dependent) Wnt signaling pathway has emerged as a likely candidate for regulating tooth replacement in continuously renewing dentitions. So far, the involvement of canonical Wnt signaling has been experimentally demonstrated predominantly in amniotes. These studies tend to show stimulation of tooth formation by activation of the Wnt pathway, and inhibition of tooth formation when blocking the pathway. Here, we report a strong and dynamic expression of the soluble Wnt inhibitor dickkopf1 (dkk1) in developing zebrafish (Danio rerio) tooth germs, suggesting an active repression of Wnt signaling during morphogenesis and cytodifferentiation of a tooth, and derepression of Wnt signaling during start of replacement tooth formation. To further analyse the role of Wnt signaling, we used different gain-of-function approaches. These yielded disjunct results, yet none of them indicating enhanced tooth replacement. Thus, masterblind (mbl) mutants, defective in axin1, mimic overexpression of Wnt, but display a normally patterned dentition in which teeth are replaced at the appropriate times and positions. Activating the pathway with LiCl had variable outcomes, either resulting in the absence, or the delayed formation, of first-generation teeth, or yielding a regular dentition with normal replacement, but no supernumerary teeth or accelerated tooth replacement. The failure so far to influence tooth replacement in the zebrafish by perturbing Wnt signaling is discussed in the light of (i) potential technical pitfalls related to dose- or time-dependency, (ii) the complexity of the canonical Wnt pathway, and (iii) species-specific differences in the nature and activity of pathway components. Finally, we emphasize the importance of in-depth knowledge of the wild-type pattern for reliable interpretations. It is hoped that our analysis can be inspiring to critically assess and elucidate the role of Wnt signaling in tooth development in polyphyodonts. PMID

  5. Cervical disc replacement surgery: indications, technique, and technical pearls.

    PubMed

    Leven, Dante; Meaike, Joshua; Radcliff, Kris; Qureshi, Sheeraz

    2017-06-01

    Cervical disc replacement (CDR) is a surgical option for appropriately indicated patients, and high success rates have been reported in the literature. Complications and failures are often associated with patient indications or technical variables, and the goal of this review is to assist surgeons in understanding these factors. Several investigations have been published in the last 5 years supporting the use of CDR in specific patient populations. CDR has been shown to be comparable or favorable to anterior cervical discectomy and fusion in several meta-analyses and mid-term follow-up studies. CDR was developed as a technique to preserve motion following a decompression procedure while minimizing several of the complications associated with fusion and posterior cervical spine procedures. Though success with cervical fusion and posterior foraminotomy has been well documented in the literature, high rates of mid- and long-term complications have been clearly established. CDR has also been associated with several complications and challenges with regard to surgical technique, though improvements in implant design have lead to an increase in utilization. Several devices currently exist and vary in terms of material, design, and outcomes. This review paper discusses indications, surgical technique, and technical pearls and reviews the CDR devices currently available.

  6. Kinematics of total facet replacement (TFAS-TL) with total disc replacement

    PubMed Central

    Voronov, Leonard I.; Havey, Robert M.; Sjovold, Simon G.; Funk, Michael; Carandang, Gerard; Zindrick, Daniel; Rosler, David M.; Patwardhan, Avinash G.

    2009-01-01

    Background Total disc replacement (TDR) and total facet replacement (TFR) have been the focus of recent kinematics evaluations. Yet their concurrent function as a total joint replacement of the lumbar spine's 3-joint complex has not been comprehensively reported. This study evaluated the effect of a TFR specifically designed to replace the natural facets and supplement the function with the natural disc and with TDR. The ability to replace degenerated facets to complement a pre-existing or simultaneously implanted TDR may allow surgeons to completely address degenerative pathologies of the 3-joint complex of the lumbar spine. We hypothesized that TFR would reproduce the biomechanical function of the natural facets when implanted in conjunction with TDR. Methods Lumbar spines (L1-5, 51.3 ± 14.2 years, N = 6) were tested sequentially as follows: (1) intact, (2) after TDR implantation, and (3) after TFR implantation in conjunction with TDR, all at L3-4. Specimens were tested in flexion-extension (+ 8 Nm to − 6 Nm), lateral bending (± 6 Nm), and axial rotation (± 5 Nm). A 400 N compressive follower preload was applied during flexion-extension tests. Three-dimensional segmental motion was recorded and analyzed using analysis of variance in Systat (Systat Software Inc., Chicago, Illinois) and multiple comparisons with Bonferroni correction. Results The TDR implantation (TDR + natural facets) allowed similar lateral bending (P = .66), but it generally increased flexion-extension (P = .06) and axial rotation (P < .05) range of motion (ROM) at the implanted level compared to intact. The TFR + TDR (following replacement of the natural facets with TFR) decreased ROM to levels similar to intact in lateral bending (P = .70) and axial rotation (P = .23). The TFR + TDR flexion-extension ROM was reduced in comparison to intact and TDR + natural facets (P < .05). Conclusions The TFR with TDR was able to restore stability to the lumbar segment after bilateral facetectomy, while

  7. Disc replacement using Pro-Disc C versus fusion: a prospective randomised and controlled radiographic and clinical study

    PubMed Central

    Ahlhelm, F.; Pitzen, T.; Steudel, W. I.; Jung, J.; Shariat, K.; Steimer, O.; Bachelier, F.; Pape, D.

    2006-01-01

    Anterior cervical discectomy and fusion (ACDF) may be considered to be the gold standard for treatment of symptomatic degenerative disc disease within the cervical spine. However, fusion of the segment may result in progressive degeneration of the adjacent segments. Therefore, dynamic stabilization procedures have been introduced. Among these, artificial disc replacement by disc prosthesis seems to be promising. However, to be so, segmental motion must be preserved. This, again, is very difficult to judge and has not yet been proven. The aim of the current study was to first analyse the segmental motion following artificial disc replacement using a disc prosthesis. A second aim was to compare both segmental motion as well as clinical result to the current gold standard (ACDF). This is a prospective controlled study. Twenty-five patients with cervical disc herniation were enrolled and assigned to either study group (receiving a disc prosthesis) or control group (receiving ACDF, using a cage with bone graft and an anterior plate.) Radiostereometric analysis was used to quantify intervertebral motion immediately as well as 3, 6, 12 and 24 weeks postoperatively. Further, clinical results were judged using visual analogue scale and neuro-examination. Cervical spine segmental motion decreased over time in the presence of disc prosthesis or ACDF. However, the loss of segmental motion is significantly higher in the ACDF group, when looked at 3, 6, 12 and 24 weeks after surgery. We observed significant pain reduction in neck and arm postoperatively, without significant difference between both groups (P > 0.05). Cervical spine disc prosthesis preserves cervical spine segmental motion within the first 6 months after surgery. The clinical results are the same when compared to the early results following ACDF. PMID:17106665

  8. Biomechanical comparison of a two-level Maverick disc replacement with a hybrid one-level disc replacement and one-level anterior lumbar interbody fusion.

    PubMed

    Erkan, Serkan; Rivera, Yamil; Wu, Chunhui; Mehbod, Amir A; Transfeldt, Ensor E

    2009-10-01

    Multilevel lumbar disc disease (MLDD) is a common finding in many patients. Surgical solutions for MLDD include fusion or disc replacement. The hybrid model, combining fusion and disc replacement, is a potential alternative for patients who require surgical intervention at both L5-S1 and L4-L5. The indications for this hybrid model could be posterior element insufficiency, severe facet pathology, calcified ligamentum flavum, and subarticular disease confirming spinal stenosis at L5-S1 level, or previous fusion surgery at L5-S1 and new symptomatic pathology at L4-L5. Biomechanical data of the hybrid model with the Maverick disc and anterior fusion are not available in the literature. To compare the biomechanical properties of a two-level Maverick disc replacement at L4-L5, L5-S1, and a hybrid model consisting of an L4-L5 Maverick disc replacement with an L5-S1 anterior lumbar interbody fusion using multidirectional flexibility test. An in vitro human cadaveric biomechanical study. Six fresh human cadaveric lumbar specimens (L4-S1) were subjected to unconstrained load in axial torsion (AT), lateral bending (LB), flexion (F), extension (E), and flexion-extension (FE) using multidirectional flexibility test. Four surgical treatments-intact, one-level Maverick at L5-S1, two-level Maverick between L4 and S1, and the hybrid model (anterior fusion at L5-S1 and Maverick at L4-L5) were tested in sequential order. The range of motion of each treatment was calculated. The Maverick disc replacement slightly reduced intact motion in AT and LB at both levels. The total FE motion was similar to the intact motion. However, the E motion is significantly increased (approximately 50% higher) and F motion is significantly decreased (30%-50% lower). The anterior fusion using a cage and anterior plate significantly reduced spinal motion compared with the condition (p<.05). No significant differences were found between two-level Maverick disc prosthesis and the hybrid model in terms of

  9. Changes in flexion-relaxation phenomenon and lumbo-pelvic kinematics following lumbar disc replacement surgery

    PubMed Central

    2013-01-01

    Background A single group prospective study. Disc prostheses are believed to contribute to the restoration of the segmental movement and the preservation of the adjacent segments. The study’s main objective was to determine if changes in neuromuscular patterns assessed using the flexion-relaxation phenomenon (FRP) can be observed following disc replacement surgery. Methods Fifteen subjects participated in this study; they were evaluated before and after lumbar disc replacement surgery. Both assessments included ten repetitions of a trunk flexion and extension movement (with and without a load), where the surface electromyography (EMG) and kinematic data were recorded. Results Following the disc replacement procedure (17.3 weeks ± 8.4), participants reported a significant reduction in their ODI and FABQ - physical activity scores. Increases in pelvic flexion as well as in erector spinae (ES) muscle activity at L5 in the flexion phase were observed. Following the disc replacement surgery, ES activity at L2 decreased during the quiet standing position. Conclusion The results of this study suggest that although improvements in disability scores and fear-avoidance related to physical activities scores were noted after a disc replacement surgery, the lumbar ROM was not modified. Nevertheless, a significant increase in the hip ROM during the flexion-extension task as well as an increase in ES muscle activity in flexion was observed following surgery. The VAS, FABQ I and ODQ scores were positively correlated with change in the muscular activities during the FRP. PMID:23842284

  10. A prospective morphological study of facet joint integrity following intervertebral disc replacement with the CHARITE Artificial Disc.

    PubMed

    Trouillier, Hans; Kern, P; Refior, H J; Müller-Gerbl, M

    2006-02-01

    In degenerative disc disease (DDD), increased loading in the posterior column increases facet joint subchondral bone density and may lead to facet joint degeneration. While spinal fusion is commonly used to treat patients with symptomatic DDD, increased stress at the levels adjacent to fusion may accelerate facet joint and adjacent segment degeneration. Artificial disc replacements have been developed as an alternative to fusion. In this prospective study, the effects of disc replacement with the CHARITE Artificial Disc on facet joint loading and integrity were evaluated. Thirteen patients aged <50 years with symptomatic DDD were recruited. Computed tomography (CT) osteoabsorptiometry was performed prior to the implantation of the CHARITE Artificial Disc and six months after. With this technique, increases or decreases in facet joint loading and integrity are indicated by corresponding changes in subchondral bone density. Changes in the distribution of load alter the distribution of the areas of maximum bone density. Clinical outcome was also assessed at pre-operative and 6 and 12 month post-operative visits using the Visual Analogue Scale back and leg pain scores, the Oswestry Disability Index and the Short Form-36 (SF-36) questionnaire. The height of the intervertebral space at the operated level was monitored by lateral X-ray. Subchondral bone density was evaluated in the facet joints of all 13 patients at the operated level, 12 patients at the level above the operated segment, and five patients at the level below the operated segment. Quantitative measurements revealed no significant increases (> or =3%) in subchondral bone density of the facet joints at any level in any patient. Significant decreases (> or =3%) in subchondral bone density were measured at the operated level in 10/13 patients, at the level above the operated segment in 6/12 patients, and at the level below the operated segment in 3/5 patients. There were no changes in the distribution of the

  11. Cervical disc replacement - emerging equivalency to anterior cervical discectomy and fusion.

    PubMed

    Buckland, Aaron J; Baker, Joseph F; Roach, Ryan P; Spivak, Jeffrey M

    2016-06-01

    Cervical disc replacement has become an acceptable alternative to anterior cervical fusion for the surgical treatment of cervical spine spondylosis resulting in radiculopathy or myelopathy following anterior discectomy and decompression. This concise overview considers the current state of knowledge regarding the continued debate of the role of cervical disc replacement with an update in light of the latest clinical trial results. A literature review was performed identifying clinical trials pertaining to the use of cervical disc replacement compared to cervical discectomy and fusion. Single level disease and two level disease were considered. Outcome data from the major clinical trials was reviewed and salient points identified. With lengthier follow-up data becoming available, the equivalence of CDR in appropriately selected cases is becoming clear. This is chiefly manifested by reduced re-operation rates and reduced incidence of adjacent level disease in those treated with arthroplasty. Cervical disc replacement shows emerging equivalence in outcomes compared to the gold standard anterior cervical discectomy and fusion. Further longer term results are anticipated to confirm this trend.

  12. An evaluation of information on the internet about a new device: the cervical artificial disc replacement.

    PubMed

    Qureshi, Sheeraz A; Koehler, Steven M; Lin, James D; Bird, Justin; Garcia, Ryan M; Hecht, Andrew C

    2012-05-01

    Cross-sectional survey. The objective of this study was to investigate the authorship, content, and quality of information available to the public on the Internet pertaining to the cervical artificial disc replacement device. The Internet is widely used by patients as an educational tool for health care information. In addition, the Internet is used as a medium for direct-to-consumer marketing. Increasing interest in cervical artificial disc replacement has led to the emergence of numerous Web sites offering information about this procedure. It is thought that patients can be influenced by information found on the Internet. A cross section of Web sites accessible to the general public was surveyed. Three commonly used search engines were used to locate 150 (50/search engine) Web sites providing information about the cervical artificial disc replacement. Each Web site was evaluated with regard to authorship and content. Fifty-three percent of the Web sites reviewed were authorized by a private physician group, 4% by an academic physician group, 13% by industry, 16% were news reports, and 14% were not otherwise categorized. Sixty-five percent of Web sites offered a mechanism for direct contact and 19% provided clear patient eligibility criteria. Benefits were expressed in 80% of Web sites, whereas associated risks were described in 35% or less. European experiences were noted in 17% of Web sites, whereas only 9% of Web sites detailed the current US experience. CONCLUSION.: The results of this study demonstrate that much of the content of the Internet-derived information pertaining to the cervical artificial disc replacement is for marketing purposes and may not represent unbiased information. Until we can confirm the content on a Web site to be accurate, patients should be cautioned when using the Internet as a source for health care information related to cervical disc replacement.

  13. Comparison of in vivo and simulator-retrieved metal-on-metal cervical disc replacements

    PubMed Central

    Kurtz, Steven M.; Ciccarelli, Lauren; Harper, Megan L.; Siskey, Ryan; Shorez, Jacob; Chan, Frank W.

    2012-01-01

    Background Cervical disc arthroplasty is regarded as a promising treatment for myelopathy and radiculopathy as an alternative to cervical spine fusion. On the basis of 2-year clinical data for the PRESTIGE® Cervical Disc (Medtronic, Memphis, Tennessee), the Food and Drug Administration recommended conditional approval in September 2006 and final approval in July 2007; however, relatively little is known about its wear and damage modes in vivo. The main objective was to analyze the tribological findings of the PRESTIGE® Cervical Disc. This study characterized the in vivo wear patterns of retrieved cervical discs and tested the hypothesis that the total disc replacements exhibited similar surface morphology and wear patterns in vitro as in vivo. Methods Ten explanted total disc replacements (PRESTIGE®, PRESTIGE® I, and PRESTIGE® II) from 10 patients retrieved after a mean of 1.8 years (range, 0.3–4.1 years) were analyzed. Wear testing included coupled lateral bending ( ±4.7°) and axial rotation ( ±3.8°) with a 49 N axial load for 5 million cycles followed by 10 million cycles of flexion-extension ( ±9.7°) with 148 N. Implant surfaces were characterized by the use of white-light interferometry, scanning electron microscopy, and energy dispersive spectroscopy. Results The explants generally exhibited a slightly discolored, elliptic wear region of varying dimension centered in the bearing center, with the long axis oriented in the medial-lateral direction. Abrasive wear was the dominant in vivo wear mechanism, with microscopic scratches generally oriented in the medial-lateral direction. Wear testing resulted in severe abrasive wear in a curvilinear fashion oriented primarily in the medial-lateral direction. All retrievals showed evidence of an abrasive wear mechanism. Conclusions This study documented important similarity between the wear mechanisms of components tested in vitro and explanted PRESTIGE® Cervical Discs; however, the severity of wear was

  14. Location change of center of rotation after single-level cervical total disc replacement with ProDisc-C.

    PubMed

    Lou, Jigang; Li, Huibo; Rong, Xin; Wu, Wenjie; Liu, Hao

    2016-01-01

    Previous studies reported that the location of the center of rotation (COR) at instrumented level after cervical total disc replacement (TDR) deviated from its preoperative location. However, currently, it is unknown whether the deviated COR is linked to the range of motion (ROM) at instrumented level. The purpose of this study was to evaluate the clinical outcomes after cervical TDR with ProDisc-C (Synthes, West Chester, PA, USA), as well as investigate the location change of COR at instrumented level and its clinical significance. A total of 23 patients who underwent single-level cervical TDR with ProDisc-C were included. Japanese Orthopaedic Association (JOA) score and Neck Disability Index (NDI) were used to assess clinical outcomes. Radiographic parameters such as cervical ROM, instrumented segmental ROM, adjacent segmental ROM, and intervertebral height were analyzed. Additionally, the location change of COR at instrumented level and its clinical significance were further analyzed by the alteration of its coordinates (COR-X, COR-Y). JOA scores increased significantly, while NDI scores decreased at final follow-up. No differences were found in cervical global ROM, instrumented segmental ROM, adjacent segmental ROM, and COR-Y at instrumented level between preoperative and final follow-up measurements (p>0.05); however, intervertebral height and COR-X increased significantly (p<0.05). Cervical global ROM, instrumented segmental ROM, and adjacent segmental ROM could be effectively maintained, and intervertebral height was increased after TDR with ProDisc-C. The location of COR at instrumented level shifted forward after cervical TDR.

  15. Translation of an engineered nanofibrous disc-like angle-ply structure for intervertebral disc replacement in a small animal model.

    PubMed

    Martin, John T; Milby, Andrew H; Chiaro, Joseph A; Kim, Dong Hwa; Hebela, Nader M; Smith, Lachlan J; Elliott, Dawn M; Mauck, Robert L

    2014-06-01

    Intervertebral disc degeneration has been implicated in the etiology of low back pain; however, the current surgical strategies for treating symptomatic disc disease are limited. A variety of materials have been developed to replace disc components, including the nucleus pulposus (NP), the annulus fibrosus (AF) and their combination into disc-like engineered constructs. We have previously shown that layers of electrospun poly(ε-caprolactone) scaffold, mimicking the hierarchical organization of the native AF, can achieve functional parity with native tissue. Likewise, we have combined these structures with cell-seeded hydrogels (as an NP replacement) to form disc-like angle-ply structures (DAPS). The objective of this study was to develop a model for the evaluation of DAPS in vivo. Through a series of studies, we developed a surgical approach to replace the rat caudal disc with an acellular DAPS and then stabilized the motion segment via external fixation. We then optimized cell infiltration into DAPS by including sacrificial poly(ethylene oxide) layers interspersed throughout the angle-ply structure. Our findings illustrate that DAPS are stable in the caudal spine, are infiltrated by cells from the peri-implant space and that infiltration is expedited by providing additional routes for cell migration. These findings establish a new in vivo platform in which to evaluate and optimize the design of functional disc replacements.

  16. Which design and biomaterial factors affect clinical wear performance of total disc replacements? A systematic review.

    PubMed

    Veruva, Sai Y; Steinbeck, Marla J; Toth, Jeffrey; Alexander, Dominik D; Kurtz, Steven M

    2014-12-01

    Total disc replacement was clinically introduced to reduce pain and preserve segmental motion of the lumbar and cervical spine. Previous case studies have reported on the wear and adverse local tissue reactions around artificial prostheses, but it is unclear how design and biomaterials affect clinical outcomes. Which design and material factors are associated with differences in clinical wear performance (implant wear and periprosthetic tissue response) of (1) lumbar and (2) cervical total disc replacements? We performed a systematic review on the topics of implant wear and periprosthetic tissue response using an advanced search in MEDLINE and Scopus electronic databases. Of the 340 references identified, 33 were retrieved for full-text evaluation, from which 16 papers met the inclusion criteria (12 on lumbar disc replacement and five on cervical disc replacement; one of the included studies reported on both lumbar and cervical disc replacement), which involved semiquantitative analysis of wear and adverse local tissue reactions along with a description of the device used. An additional three papers were located by searching bibliographies of key articles. There were seven case reports, three case series, two case-control studies, and seven analytical studies. The Methodological Index for Non-randomized Studies (MINORS) Scale was used to score case series and case-control studies, which yielded mean scores of 10.3 of 16 and 17.5 of 24, respectively. In general, the case series (three) and case-control (two) studies were of good quality. In lumbar regions, metal-on-polymer devices with mobile-bearing designs consistently generated small and large polymeric wear debris, triggering periprosthetic tissue activation of macrophages and giant cells, respectively. In the cervical regions, metal-on-polymer devices with fixed-bearing designs had similar outcomes. All metal-on-metal constructs tended to generate small metallic wear debris, which typically triggered an

  17. Wear in ceramic on ceramic type lumbar total disc replacement: effect of radial clearance.

    PubMed

    Shankar, S; Kesavan, D

    2015-01-01

    The wear of the bearing surfaces of total disc replacement (TDR) is a key problem leads to reduction in the lifetime of the prosthesis and it mainly occurs due to the range of clearances of the articulating surface between the superior plate and core. The objective of this paper is to estimate the wear using finite element concepts considering the different radial clearances between the articulating surfaces of ceramic on ceramic type Lumbar Total Disc Replacement (LTDR). The finite element (FE) model was subjected to wear testing protocols according to loading profile of International Standards Organization (ISO) 18192 standards through 10 million cycles. The radial clearance value of 0.05 mm showed less volumetric wear when compared with other radial clearance values. Hence, low radial clearance values are suitable for LTDR to minimize the wear.

  18. Effect of lubricants on friction in laboratory tests of a total disc replacement device.

    PubMed

    Moghadas, Parshia; Mahomed, Aziza; Hukins, David W L; Shepherd, Duncan E T

    2013-09-01

    Some designs of total disc replacement devices have articulating bearing surfaces, and these devices are tested in vitro with a lubricant of diluted calf serum. It is believed that the lubricant found in total disc replacement devices in vivo is interstitial fluid that may have properties between that in Ringer's solution and diluted calf serum. To investigate the effect of lubricants, a set of friction tests were performed on a generic model of a metal against metal ball-and-socket total disc replacement device. Two devices were tested: one with a ball radius of 10 mm and other with a ball radius of 16 mm; each device had a radial clearance of 0.015 mm. A spine simulator was used to measure frictional torque for each device in axial rotation, flexion-extension and lateral bending at frequencies of 0.25-2 Hz, under 1200 N axial load. Each device was tested with two different lubricants: a solution of new born calf serum diluted with deionised water and Ringer's solution. The results showed that the frictional torque generated between the bearing surfaces was significantly higher in Ringer's solution than in diluted calf serum. The use of Ringer's solution as a lubricant provides a stringent test condition to detect possible problems. Diluted calf serum is more likely to provide an environment closer to that in vivo. However, the precise properties of the fluid lubricating a total disc replacement device are not known; hence, tests using diluted calf serum may not necessarily give the same results as those obtained in vivo.

  19. Clinical outcome of lumbar total disc replacement using ProDisc-L in degenerative disc disease: minimum 5-year follow-up results at a single institute.

    PubMed

    Park, Chun-Kun; Ryu, Kyeong-Sik; Lee, Ki-Yeol; Lee, Hong-Jae

    2012-04-15

    A retrospective clinical data analysis. To determine the therapeutic effectiveness of lumbar total disc replacement (TDR) using ProDisc-L (Synthes Spine, West Chester, PA) in the patients with degenerative disc diseases (DDD) with a minimum follow-up of 5 years. Early successful clinical results of lumbar TDR have been reported. However, few reports have published its therapeutic effectiveness in the long term. The patients were examined preoperatively and at 3 months, 1 year, 2 years, and more than 5 years postoperatively, and assessed using visual analog scale (VAS), Oswestry disability index (ODI), physical health component summary (PCS) of the 36-Item Short Form Health Survey questionnaire, and sporting activity scale scores. At last follow-up visits, two additional questions were asked: satisfaction with surgery and willingness to undergo the same treatment. Finally, clinical success was assessed using the Food and Drug Administration definition. Thirty-five patients were included in the study. The mean follow-up period was 72 months (6 years). Postoperatively, all outcome measure scores (VAS, mean ODI, PCS, and sports activity scores) immediately improved and these improvements were maintained at last follow-up visits with statistical significance. However, outcome score improvements were observed to be slightly, though significantly, lower at last follow-up visits than at 1 or 2 years postoperatively. Eighty-eight percent of patients were "satisfied" or "somewhat satisfied" with treatment and 60% were prepared to undergo the same treatment again. Twenty-five patients (71.4%) achieved clinical success. This study reveals that lumbar TDR using ProDisc-L is a safe and effective treatment for chronic back pain caused by lumbar DDD as assessed at more than 5 years postoperatively. Nevertheless, outcome scores were slightly, though significantly lower at last follow-up visits than at 1 and 2 years postoperatively. A longer-term follow-up study is warranted.

  20. A 6-DOF parallel bone-grinding robot for cervical disc replacement surgery.

    PubMed

    Tian, Heqiang; Wang, Chenchen; Dang, Xiaoqing; Sun, Lining

    2017-05-24

    Artificial cervical disc replacement surgery has become an effective and main treatment method for cervical disease, which has become a more common and serious problem for people with sedentary work. To improve cervical disc replacement surgery significantly, a 6-DOF parallel bone-grinding robot is developed for cervical bone-grinding by image navigation and surgical plan. The bone-grinding robot including mechanical design and low level control is designed. The bone-grinding robot navigation is realized by optical positioning with spatial registration coordinate system defined. And a parametric robot bone-grinding plan and high level control have been developed for plane grinding for cervical top endplate and tail endplate grinding by a cylindrical grinding drill and spherical grinding for two articular surfaces of bones by a ball grinding drill. Finally, the surgical flow for a robot-assisted cervical disc replacement surgery procedure is present. The final experiments results verified the key technologies and performance of the robot-assisted surgery system concept excellently, which points out a promising clinical application with higher operability. Finally, study innovations, study limitations, and future works of this present study are discussed, and conclusions of this paper are also summarized further. This bone-grinding robot is still in the initial stage, and there are many problems to be solved from a clinical point of view. Moreover, the technique is promising and can give a good support for surgeons in future clinical work.

  1. Finite Element Study of a Lumbar Intervertebral Disc Nucleus Replacement Device

    PubMed Central

    Coogan, Jessica S.; Francis, W. Loren; Eliason, Travis D.; Bredbenner, Todd L.; Stemper, Brian D.; Yoganandan, Narayan; Pintar, Frank A.; Nicolella, Daniel P.

    2016-01-01

    Nucleus replacement technologies are a minimally invasive alternative to spinal fusion and total disc replacement that have the potential to reduce pain and restore motion for patients with degenerative disc disease. Finite element modeling can be used to determine the biomechanics associated with nucleus replacement technologies. The current study focuses on a new nucleus replacement device designed as a conforming silicone implant with an internal void. A validated finite element model of the human lumbar L3–L4 motion segment was developed and used to investigate the influence of the nucleus replacement device on spine biomechanics. In addition, the effect of device design changes on biomechanics was determined. A 3D, L3–L4 finite element model was constructed from medical imaging data. Models were created with the normal intact nucleus, the nucleus replacement device, and a solid silicone implant. Probabilistic analysis was performed on the normal model to provide quantitative validation metrics. Sensitivity analysis was performed on the silicone Shore A durometer of the device. Models were loaded under axial compression followed by flexion/extension, lateral bending, or axial rotation. Compressive displacement, endplate stresses, reaction moment, and annulus stresses were determined and compared between the different models. The novel nucleus replacement device resulted in similar compressive displacement, endplate stress, and annulus stress and slightly higher reaction moment compared with the normal nucleus. The solid implant resulted in decreased displacement, increased endplate stress, decreased annulus stress, and decreased reaction moment compared with the novel device. With increasing silicone durometer, compressive displacement decreased, endplate stress increased, reaction moment increased, and annulus stress decreased. Finite element analysis was used to show that the novel nucleus replacement device results in similar biomechanics compared with

  2. Finite Element Study of a Lumbar Intervertebral Disc Nucleus Replacement Device.

    PubMed

    Coogan, Jessica S; Francis, W Loren; Eliason, Travis D; Bredbenner, Todd L; Stemper, Brian D; Yoganandan, Narayan; Pintar, Frank A; Nicolella, Daniel P

    2016-01-01

    Nucleus replacement technologies are a minimally invasive alternative to spinal fusion and total disc replacement that have the potential to reduce pain and restore motion for patients with degenerative disc disease. Finite element modeling can be used to determine the biomechanics associated with nucleus replacement technologies. The current study focuses on a new nucleus replacement device designed as a conforming silicone implant with an internal void. A validated finite element model of the human lumbar L3-L4 motion segment was developed and used to investigate the influence of the nucleus replacement device on spine biomechanics. In addition, the effect of device design changes on biomechanics was determined. A 3D, L3-L4 finite element model was constructed from medical imaging data. Models were created with the normal intact nucleus, the nucleus replacement device, and a solid silicone implant. Probabilistic analysis was performed on the normal model to provide quantitative validation metrics. Sensitivity analysis was performed on the silicone Shore A durometer of the device. Models were loaded under axial compression followed by flexion/extension, lateral bending, or axial rotation. Compressive displacement, endplate stresses, reaction moment, and annulus stresses were determined and compared between the different models. The novel nucleus replacement device resulted in similar compressive displacement, endplate stress, and annulus stress and slightly higher reaction moment compared with the normal nucleus. The solid implant resulted in decreased displacement, increased endplate stress, decreased annulus stress, and decreased reaction moment compared with the novel device. With increasing silicone durometer, compressive displacement decreased, endplate stress increased, reaction moment increased, and annulus stress decreased. Finite element analysis was used to show that the novel nucleus replacement device results in similar biomechanics compared with the

  3. [Biomechanical research on morphometric changes in adjacent inferior cervical intervertebral foramen after artificial disc replacement].

    PubMed

    Wang, Bin; Zhang, Zhigang; Li, Kanghua

    2007-10-01

    To explore changes in the height and width of the cervical intervertebral foramina of C6.7 before and after the C5.6 discetomy, the replacement or the anterior intervertebral fusion so as to provide the theoretical basis for the clinical practice. Eleven fresh cervical spinal specimens were obtained from young adult cadavers. The specimens of C5.6 were divided into the integrity group, the discectomy group, the artificial disc replacement group, and the intervertebral fusion group. The range of variety (ROV) of the C6.7 intervertebral foramen dimensions (height, width) before and after the loading tests (0.75, 1.50 Nm) were measured in the 4 groups. The C6.7 intervetebral foramen height and width increased significantly during flexion (P < 0.01) but decreased significantly during extension (P < 0.01). There was a significant difference between the two test conditions in each of the 4 groups (P < 0.01). However, in the two test conditions there was no significant difference in ROV of the C6,7 intervetebral foramen height and width during flexion and extension between the integrity group, the discectomy, and the artificial disc replacement group (P > 0.05), but a significant difference in the above changes existed in the intervertebral fusion group when compared with the other 3 groups (P < 0.05). In the same group and under the same conditions, the ROV of the C6.7 intervetebral foramen height and width was significantly different in the two test conditions (P < 0.01). The results have indicated that artificial disc replacement can meet the requirements of the normal cervical vitodynamics. The adjacent inferior cervical intervetebral foramen increases during flexion but decreases during extension. The intervertebral fusion is probably one of the causes for the cervical degeneration or the accelerated degeneration and for the cervical spondylotic radiculopathy and the brachial plexus compression.

  4. Mixed reality simulation of rasping procedure in artificial cervical disc replacement (ACDR) surgery.

    PubMed

    Halic, Tansel; Kockara, Sinan; Bayrak, Coskun; Rowe, Richard

    2010-10-07

    Until quite recently spinal disorder problems in the U.S. have been operated by fusing cervical vertebrae instead of replacement of the cervical disc with an artificial disc. Cervical disc replacement is a recently approved procedure in the U.S. It is one of the most challenging surgical procedures in the medical field due to the deficiencies in available diagnostic tools and insufficient number of surgical practices For physicians and surgical instrument developers, it is critical to understand how to successfully deploy the new artificial disc replacement systems. Without proper understanding and practice of the deployment procedure, it is possible to injure the vertebral body. Mixed reality (MR) and virtual reality (VR) surgical simulators are becoming an indispensable part of physicians' training, since they offer a risk free training environment. In this study, MR simulation framework and intricacies involved in the development of a MR simulator for the rasping procedure in artificial cervical disc replacement (ACDR) surgery are investigated. The major components that make up the MR surgical simulator with motion tracking system are addressed. A mixed reality surgical simulator that targets rasping procedure in the artificial cervical disc replacement surgery with a VICON motion tracking system was developed. There were several challenges in the development of MR surgical simulator. First, the assembly of different hardware components for surgical simulation development that involves knowledge and application of interdisciplinary fields such as signal processing, computer vision and graphics, along with the design and placements of sensors etc . Second challenge was the creation of a physically correct model of the rasping procedure in order to attain critical forces. This challenge was handled with finite element modeling. The third challenge was minimization of error in mapping movements of an actor in real model to a virtual model in a process called

  5. Mixed reality simulation of rasping procedure in artificial cervical disc replacement (ACDR) surgery

    PubMed Central

    2010-01-01

    Background Until quite recently spinal disorder problems in the U.S. have been operated by fusing cervical vertebrae instead of replacement of the cervical disc with an artificial disc. Cervical disc replacement is a recently approved procedure in the U.S. It is one of the most challenging surgical procedures in the medical field due to the deficiencies in available diagnostic tools and insufficient number of surgical practices For physicians and surgical instrument developers, it is critical to understand how to successfully deploy the new artificial disc replacement systems. Without proper understanding and practice of the deployment procedure, it is possible to injure the vertebral body. Mixed reality (MR) and virtual reality (VR) surgical simulators are becoming an indispensable part of physicians’ training, since they offer a risk free training environment. In this study, MR simulation framework and intricacies involved in the development of a MR simulator for the rasping procedure in artificial cervical disc replacement (ACDR) surgery are investigated. The major components that make up the MR surgical simulator with motion tracking system are addressed. Findings A mixed reality surgical simulator that targets rasping procedure in the artificial cervical disc replacement surgery with a VICON motion tracking system was developed. There were several challenges in the development of MR surgical simulator. First, the assembly of different hardware components for surgical simulation development that involves knowledge and application of interdisciplinary fields such as signal processing, computer vision and graphics, along with the design and placements of sensors etc . Second challenge was the creation of a physically correct model of the rasping procedure in order to attain critical forces. This challenge was handled with finite element modeling. The third challenge was minimization of error in mapping movements of an actor in real model to a virtual model in a

  6. Comparison between total disc replacement and hybrid construct at two lumbar levels with minimum follow-up of two years.

    PubMed

    Andrieu, K; Allain, J; Longis, P-M; Steib, J-P; Beaurain, J; Delécrin, J

    2017-02-01

    Lower back pain due to degenerative disc disease is a therapeutic challenge in young patients. Although arthrodesis is currently the gold standard for surgical treatment, improvement in total disc replacement techniques makes it possible to preserve segmental mobility with good results in one-level surgery. Nevertheless, the French National Health Authority does not recommend total disc replacement for multilevel surgery. Thus, hybrid constructs that combine one-level disc replacement with arthrodesis have been developed for multilevel indications. The outcome of two-level lumbar disc arthroplasty does not differ from hybrid constructs. The clinical and radiographic outcomes of disc arthroplasty were compared to hybrid constructs for two-level degenerative disc disease in 72 patients after a continuous follow-up of at least 2 years. The patients were divided into two groups that were similar for the indication and type of implants. There was no statistical difference in pain relief (-3.9 points versus -3.5 points for lumbar VAS) or reduction in ODI (-29.5% versus -27.0%) between TDR and hybrid constructs, respectively. There was no statistical difference in range of motion at the level of arthroplasty (8.4° versus 7.6°) and no kinematic dysfunction was identified. The re-operation rate at two years for persistent lumbar pain was respectively 6.7% for two-level disc arthroplasty and 4.3% for hybrid constructs. The complication rate was 4.8% and 8.7% respectively. No difference was found in this comparison of two homogeneous series between two-level disc arthroplasty and hybrid constructs for the treatment of degenerative disc disease after two years of follow-up. Two-level disc arthroplasty may be an alternative for young patients depending on an evaluation of long-term results. Cohort observational study level III. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  7. Cardiac pathology after valve replacement by disc prosthesis. A study of 61 necropsy patients.

    PubMed

    Roberts, W C; Fishbein, M C; Golden, A

    1975-05-01

    Clinical and necropsy observations are described in 61 patients who had one or more cardiac valves replaced with a discoid prosthesis of the Hufnagel type. The most common (31 percent) cause of death among the 45 patients who died early (less than 65 days after operation) appeared to be prosthetic disproportion; that is, the prothesis was too big for the aorta or ventricular cavity into which it was inserted so that inadequate space was present between the margins of the disc and the endocardium of ventricle or intima of aorta. Prosthetic thrombosis occurred in only 3 of the 45 patients who died early, but poppet movement appeared considerably altered in each. In contrast, thrombi were observed on a prosthesis in 14 of the 16 patients who died late (4 to 47 months [average 21] postoperatively), but in none did the thrombi appear of sufficient size to alter poppet function. Escessive bleeding occurred in 11 (24 percent) of the 45 early deaths and was primarily related to the insertion of a patch in the root of the aorta. Uncorrected valvular disease either by itself or by its ability to alter function of the prosthesis appeared responsible for death in 6 (13 percent) of the 45 patients who died early and in 2 (6 percent) of the 16 who died late. Insertion of a mitral poppet disc in a patient with uncorrected aortic regurgitation, even of mild degree, may be hazardous because the aortic regurgitant jet stream may interfere with proper function of the mitral disc. Likewise, insertion of a poppet disc only in the aortic valve position in a patient with combined aortic and mitral regurgitation may considerably increase the degree of mitral incompetence because the aortic prosthesis is intrinsically obstructive. Disc wear or variance was observed in all but one prosthesis in place for more than 1 year. Although hemolytic anemia of significant degree was not observed in any of the 16 patients who died late, the occurrence of renal hemosiderosis in 13 of the 16 patients

  8. Total ankle replacement using HINTEGRA, an unconstrained, three-component system: surgical technique and pitfalls.

    PubMed

    Barg, Alexej; Knupp, Markus; Henninger, Heath B; Zwicky, Lukas; Hintermann, Beat

    2012-12-01

    Total ankle replacement (TAR) has become a valuable treatment option in patients with end-stage ankle osteoarthritis. One popular 3-component system, the HINTEGRA TAR, is an unconstrained system that provides inversion-eversion stability. More natural biomechanics of the replaced ankle may be expected when anatomic considerations drive prosthesis design. The HINTEGRA prosthesis includes 2 anatomically contoured metal components and a polyethylene insert, providing axial rotation and physiologic flexion-extension mobility. This article describes the HINTEGRA TAR design and surgical technique. Use of the prosthesis for complex hindfoot reconstruction in patients with an osteoarthritic, varus, or valgus ankle deformity is described.

  9. Total disc replacement versus fusion for lumbar degenerative disc disease: a systematic review of overlapping meta-analyses.

    PubMed

    Ding, Fan; Jia, Zhiwei; Zhao, Zhigang; Xie, Lin; Gao, Xinfeng; Ma, Dezhang; Liu, Ming

    2017-03-01

    Although many meta-analyses have been performed to compare total disc replacement (TDR) and fusion for treating lumbar degenerative disc disease (LDDD), their findings are inconsistent. This study aimed to conduct a systematic review of overlapping meta-analyses comparing TDR with fusion for treating LDDD, to assist decision makers in selection among conflicting meta-analyses, and to provide treatment recommendations based on the best available evidence. This study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. Multiple databases were comprehensively searched for meta-analyses comparing TDR with fusion for treating LDDD. Meta-analyses only comprising randomised controlled trials (RCTs) were included. Two authors independently assessed meta-analysis quality and extracted data. The Jadad decision algorithm was used to ascertain which meta-analyses represented the best evidence. A total of five meta-analyses were included. All these studies only included RCTs were determined as Level-II evidence. The scores of Assessment of Multiple Systematic Reviews (AMSTAR) ranged from 6 to 9 (median 7). A high-quality Cochrane review was chosen according to the Jadad algorithm. This best available evidence found that statistical significances were observed between TDR and fusion for LDDD regarding disability, pain relief, and pain in the short term, but it was not over clinically important differences. The prevent effects on adjacent segment and facet joint degeneration, as the primary goal of adopting TDR stated by the manufacturers, were not appropriately evaluated. There is discord in results from meta-analyses that assessed TDR and fusion for LDDD. According to this systematic review of overlapping meta-analyses comparing TDR and fusion for LDDD, the current best available evidence suggests that TDR may be an effective technique for the treatment of selected patients with LDDD, and is at least equal to lumbar

  10. Total disc replacement in the cervical spine: a systematic review evaluating long-term safety

    PubMed Central

    Anderson, Paul A.; Hashimoto, Robin

    2012-01-01

    Study design: Systematic review. Clinical questions: What are the rates and causes of subsequent surgeries? What is the long-term complication rates following cervical artificial disc replacement (C-ADR)? How do these rates change over time? Methods: A systematic review was undertaken for articles published up to October 2011. Electronic databases and reference lists of key articles were searched to identify comparative and non-comparative studies reporting long-term (≥ 48 months) complications of C-ADR. Two independent reviewers assessed the strength of evidence using the GRADE criteria and disagreements were resolved by consensus. Results: Two RCTs reporting outcomes following C-ADR (Bryan disc, Prestige disc) versus anterior cervical discectomy and fusion (ACDF) at follow-ups of 4 to 5 years were found; five case series reporting outcomes following C-ADR at follow-ups of 4 to 8 years were identified. Secondary surgery rates were similar or slightly lower following C-ADR compared with fusion at 4 to 5 years postoperatively. In one small subset of an RCT, rates of adjacent disc heterotopic ossification were lower in C-ADR patients than in those treated with fusion. Rates of other adverse events were similar between treatment groups. Conclusions: There is low evidence on the long-term safety outcomes following C-ADR. Additional comparative studies with follow-up of at least 4 years are needed to fully understand the long-term safety outcomes of C-ADR compared with fusion. PMID:23236309

  11. The Role of Posterior Longitudinal Ligament in Cervical Disc Replacement: An Ovine Cadaveric Biomechanical Analysis

    PubMed Central

    Yu, Cheng-Cheng; Hao, Ding-Jun; Ma, Yu-Li; Huang, Da-Geng; Li, Hou-Kun; Feng, Hang; Hou, Qian

    2016-01-01

    Background Cervical disc replacement (CDR) has been widely used to restore and maintain mobility and function of the treated and adjacent motion segments. Posterior longitudinal ligament (PLL) resection has been shown to be efficient in anterior cervical decompression and fusion. However, less is known about the biomechanical effect of PLL removal versus preservation in cervical disc arthroplasty. Material/Methods Three motion segments of 24 ovine cervical spines (C2–C5) were evaluated in a robotic spine system with axial compressive loads of 50 N. These cervical spines were divided in three groups according to the following conditions: (1) intact spine, (2) C3/C4 CDR with the Prestige LP prosthesis and PLL preservation, and (3) C3/C4 CDR with the Prestige LP prosthesis and PLL removal. The ranges of motion (ROMs) were recorded and analyzed in each group. Results The C3/C4 ROM in group 3 (CDR with PLL removed) increased significantly in flexion-extension and axial rotation compared with group 1 (intact spine). Moreover, in flexion-extension, the mean total ROM was significantly larger in group 3 than in group 1. All the ROM observed in group 2 (CDR with PLL preserved) did not significantly differ from the ROM observed in group 1. Conclusions Compared with intact spines, CDR with PLL removal partly increased ROM. Moreover, the ROM in CDR with PLL preservation did not significantly differ from the ROM observed in intact spines. The PLL appears to contribute to the balance and stability of the cervical spine and should thus be preserved in cervical disc replacement provided that the posterior longitudinal ligament is not degenerative and the compression can be removed without PLL takedown. PMID:27243444

  12. Augmentation improves human cadaveric vertebral body compression mechanics for lumbar total disc replacement.

    PubMed

    Yoder, Jonathon H; Auerbach, Joshua D; Maurer, Philip M; Erbe, Erik M; Entrekin, Dean; Balderston, Richard A; Bertagnoli, Rudolf; Elliott, Dawn M

    2010-04-20

    Cadaveric biomechanical study. To quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. This study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, and specimens were block-randomized by bone density into augmentation and control groups. A semiconstrained keeled lumbar disc replacement device was implanted, providing 50% endplate coverage. Vertebral augmentation of 17.6% +/- 0.9% vertebral volume fill with Cortoss was performed on the augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6 mm. The load-displacement response for all specimens was nonlinear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases, the augmented group was 2 times higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2 times and 1.3 times greater than control, respectively. The subfailure stress and apparent modulus with augmentation were moderately correlated with bone density whereas the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, whereas the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and the control groups. Augmentation improved the

  13. Augmentation Improves Human Cadaveric Vertebral Body Compression Mechanics For Lumbar Total Disc Replacement

    PubMed Central

    Yoder, Jonathon H.; Auerbach, Joshua D.; Maurer, Philip M.; Erbe, Erik M.; Entrekin, Dean; Balderston, Richard A.; Bertagnoli, Rudolf; Elliott, Dawn M.

    2012-01-01

    Study Design Cadaveric biomechanical study. Objectives Quantify the effects of vertebral body augmentation on biomechanics under axial compression by a total disc replacement (TDR) implant. Summary of Background Data TDR is a surgical alternative to lumbar spinal fusion to treat degenerative disc disease. Osteoporosis in the adjacent vertebrae to the interposed TDR may lead to implant subsidence or vertebral body fracture. Vertebral augmentation is used to treat osteoporotic compression fracture. The study sought to evaluate whether vertebral augmentation improves biomechanics under TDR axial loading. Methods Forty-five L1-L5 lumbar vertebral body segments with intact posterior elements were used. Peripheral quantitative computed tomography scans were performed to determine bone density, block randomizing specimens by bone density into augmentation and control groups. A semi-constrained keeled lumbar disc replacement device was implanted providing 50% endplate coverage. Vertebral augmentation of 17.6 ± 0.9% vertebral volume fill with Cortoss was performed on augmentation group. All segments underwent axial compression at a rate of 0.2 mm/s to 6mm. Results The load-displacement response for all specimens was non-linear. Subfailure mechanical properties with augmentation were significantly different from control; in all cases the augmented group was 2× higher than control. At failure, the maximum load and stiffness with augmentation was not significantly different from control. The maximum apparent stress and modulus with augmentation were 2× and 1.3× greater than control, respectively. The subfailure stress and apparent modulus with augmentation was moderately correlated with bone density while the control subfailure properties were not. The augmented maximum stress was not correlated with bone density, while the control was weakly correlated. The maximum apparent modulus was moderately correlated with bone density for both the augmented and control groups

  14. Androgen deficiency in older men: indications, advantages, and pitfalls of testosterone replacement therapy.

    PubMed

    McGill, John J; Shoskes, Daniel A; Sabanegh, Edmund S

    2012-11-01

    The decline in testosterone with age has been associated with specific physical changes that affect quality of life and life expectancy, although a cause-and-effect relationship is yet to be established. While female menopause is rapid and well described, "male menopause" or androgen decline in older men is gradual and marked by nonspecific symptoms. This makes diagnosis of true testosterone deficiency and prediction of response to testosterone replacement therapy (TRT) challenging. This article reviews androgen decline in men, focusing on those over age 40, and covers symptoms, indications, contraindications,diagnosis, treatments, and the risks and benefits of treatment [corrected].

  15. Clinical and radiographic outcomes of cervical disc replacement with a new prosthesis.

    PubMed

    Miao, Jinhao; Yu, Fengbin; Shen, Ye; He, Naya; Kuang, Yong; Wang, Xinwei; Chen, Deyu

    2014-06-01

    Anterior cervical discectomy and interbody fusion was a classical treatment for cervical degenerative disc disease (CDDD). However, the rigid fusion also leads to a reduction in normal cervical spine motion and to increased biomechanical stress at adjacent levels, which in turn accelerates degenerative changes of the discs at these levels. Cervical disc replacement (CDR) is a new technology with the aim of addressing the limitations of fusion procession and preserving motion at the treated level. Discover prosthesis (DePuy Spine, Raynham, MA, USA) is a new type artificial disc and there are few reports about it. The purpose of this study was to analyze the primary clinical and radiographic outcomes of CDR with Discover prosthesis to treat mono- or bi-segment CDDD in a Chinese population. The study design was prospective and single-center clinical trial of the Discover prosthesis in the treatment of patients with mono- or bi-segment CDDD. Seventy-nine patients with 102 Discover prosthesis arthroplasty performed (56 mono-segment and 23 bi-segment) were evaluated. Clinical outcomes based on Japanese Orthopaedic Association (JOA), visual analog scale (VAS) pain score, and Odom's scale and radiographic outcomes including the anterior disc heights (ADH), posterior disc heights (PDH), range of motion, and performance of heterotopic ossification (HO) of the operative segment were assessed. Clinical and radiographic follow-up was performed. Preoperative and postoperative ADH, PDH, and range of motion were measured from lateral and flexion-extension radiographs. The paired t test was used to assess the difference of clinical and radiographic outcomes before and after operation. The performance of HO was observed by two independent MD. The mean follow-up time for all the patients was 31.6 months, ranging from 24 to 43 months. Mean preoperative JOA score was 9.5, and VAS overall pain score was 7.2. At 2-, 6-, 12-, and 24-month follow-up, the mean JOA score was 14.1, 14.7, 15

  16. Segmental kinematics and adjacent level degeneration following disc replacement versus fusion: RCT with three years of follow-up.

    PubMed

    Nabhan, A; Steudel, W I; Nabhan, Ah; Pape, D; Ishak, B

    2007-01-01

    Prospective, randomized and controlled clinical and radiological study. The aim of this study was to assess the segmental kinematics and clinical outcome of disc replacement with ProDisc C versus anterior cervical discectomy and fusion (ACDF) for monosegmental disease 3 years after surgery. Anterior cervical discectomy and fusion (ACDF), including plate fixation, is an accepted technique for treatment of symptomatic degenerative disc disease (DDD). However, various studies could show that fusion of a relative mobile spinal segment leads to heightens of stresses on the discs below and above fusion, which is manifested as adjacent level degeneration. Intervertebral disc replacement has been attempted to restore intervertebral disc height and to maintain segmental motion, which may be thought to avoid the accelerated degeneration to the adjacent level. In earlier studies, we could show that ProDisc C could maintain segmental motion for 1 year after surgery. 49 patients with cervical disc herniation underwent arthroplasty of a single level using ProDisc C disc prosthesis or received fusion using a cage and anterior titanium plate fixation. Clinical outcome was assessed using the visual analogue scale (VAS) and the neck disability index (NDI). Radiostereometry was performed immediately postoperative and then after 1, 2, and 3 years after surgery to quantify the segmental kinematics. The range of motion of the treated segment with prosthesis remained unchanged 3 years after surgery in comparison to the 1-year result. The prosthesis shows a significant segmental motion in contrast to the fusion group at each RSA examination time (p < 0.05). After both procedures, a significant pain reduction in neck and arm was observed, without significant differences between both groups. During the course of the 3 years follow-up, no patients of the prosthesis group required further surgical intervention.

  17. Severe impingement of lumbar disc replacements increases the functional biological activity of polyethylene wear debris.

    PubMed

    Baxter, Ryan M; Macdonald, Daniel W; Kurtz, Steven M; Steinbeck, Marla J

    2013-06-05

    Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume of particles in all

  18. Severe Impingement of Lumbar Disc Replacements Increases the Functional Biological Activity of Polyethylene Wear Debris

    PubMed Central

    Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

    2013-01-01

    Background: Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. Methods: The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Results: Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume

  19. Rare complications of osteolysis and periprosthetic tissue reactions after hybrid and non-hybrid total disc replacement.

    PubMed

    Veruva, Sai Y; Lanman, Todd H; Hanzlik, Josa A; Kurtz, Steven M; Steinbeck, Marla J

    2015-05-01

    Few complications have been reported for lumbar total disc replacement (TDR) and hybrid TDR fixations. This study evaluated retrieved implants and periprosthetic tissue reactions for two cases of osteolysis following disc arthroplasty with ProDisc-L prostheses. Implants were examined for wear and surface damage, and tissues for inflammation, polyethylene wear debris (polarized light microscopy) and metal debris (energy-dispersive X-ray spectroscopy). Despite initial good surgical outcomes, osteolytic cysts were noted in both patients at vertebrae adjacent to the implants. For the hybrid TDR case, heterotopic ossification and tissue necrosis due to wear-induced inflammation were observed. In contrast, the non-hybrid implant showed signs of abrasion and impingement, and inflammation was observed in tissue regions with metal and polyethylene wear debris. In both cases, wear debris and inflammation may have contributed to osteolysis. Surgeons using ProDisc prostheses should be aware of these rare complications.

  20. Radiographic total disc replacement angle measurement accuracy using the Oxford Cobbometer: precision and bias

    PubMed Central

    Stafylas, Kosmas; McManus, John; Schizas, Constantin

    2008-01-01

    Total disc replacement (TDR) clinical success has been reported to be related to the residual motion of the operated level. Thus, accurate measurement of TDR range of motion (ROM) is of utmost importance. One commonly used tool in measuring ROM is the Oxford Cobbometer. Little is known however on its accuracy (precision and bias) in measuring TDR angles. The aim of this study was to assess the ability of the Cobbometer to accurately measure radiographic TDR angles. An anatomically accurate synthetic L4–L5 motion segment was instrumented with a CHARITE artificial disc. The TDR angle and anatomical position between L4 and L5 was fixed to prohibit motion while the motion segment was radiographically imaged in various degrees of rotation and elevation, representing a sample of possible patient placement positions. An experienced observer made ten readings of the TDR angle using the Cobbometer at each different position. The Cobbometer readings were analyzed to determine measurement accuracy at each position. Furthermore, analysis of variance was used to study rotation and elevation of the motion segment as treatment factors. Cobbometer TDR angle measurements were most accurate (highest precision and lowest bias) at the centered position (95.5%), which placed the TDR directly inline with the x-ray beam source without any rotation. In contrast, the lowest accuracy (75.2%) was observed in the most rotated and off-centered view. A difference as high as 4° between readings at any individual position, and as high as 6° between all the positions was observed. Furthermore, the Cobbometer was unable to detect the expected trend in TDR angle projection with changing position. Although the Cobbometer has been reported to be reliable in different clinical applications, it lacks the needed accuracy to measure TDR angles and ROM. More accurate ROM measurement methods need to be developed to help surgeons and researchers assess radiological success of TDRs. PMID:18496719

  1. Maverick total disc replacement in a real-world patient population: a prospective, multicentre, observational study.

    PubMed

    Assaker, Richard; Ritter-Lang, Karsten; Vardon, Dominique; Litrico, Stéphane; Fuentes, Stéphane; Putzier, Michael; Franke, Jörg; Jarzem, Peter; Guigui, Pierre; Nakach, Gérard; Le Huec, Jean-Charles

    2015-09-01

    Controlled trials have shown that total disc replacement (TDR) can provide pain and disability relief to patients with degenerative disc disease; however, whether these outcomes can also be achieved for patients treated in normal surgical practice has not been well documented. This prospective, international study observed changes in disability and back pain in 134 patients who were implanted with Maverick TDR within the framework of routine clinical practice and followed for 2 years post-surgery. Primary and secondary outcomes were the differences from baseline to 6 months post-surgery in the means of the Oswestry Disability Index and the change in back pain intensity assessed on a 10-cm visual analogue scale, respectively. Mean patient age at surgery was 43 years, but ranged up to 65 years. One hundred twenty-three patients had an implant at one level, 10 patients at two levels, and one patient at three levels. Statistically significant improvements in mean disability (-25.4) and low back pain intensity (-4.0) scores were observed at 6 months postoperatively (P < 0.0001 for both) in the hands of experienced surgeons (>10 TDRs per centre). During the study, 56 patients (42 %) experienced a complication or adverse event. This is the first international observational study to report outcomes of TDR in real-world clinical settings. We showed statistically significant improvements in disability and pain scores at 6 months following Maverick TDR, which were maintained for 2 years alongside an acceptable rate of perioperative complications. The safety and tolerability shown in this observational study were comparable to those from controlled trials.

  2. Artificial total disc replacement versus fusion for the cervical spine: a systematic review

    PubMed Central

    Winkler, Roman; Mad, Philipp

    2010-01-01

    Cervical total disc replacement (CTDR) has been increasingly used as an alternative to fusion surgery in patients with pain or neurological symptoms in the cervical spine who do not respond to non-surgical treatment. A systematic literature review has been conducted to evaluate whether CTDR is more efficacious and safer than fusion or non-surgical treatment. Published evidence up to date is summarised qualitatively according to the GRADE methodology. After 2 years of follow-up, studies demonstrated statistically significant non-inferiority of CTDR versus fusion with respect to the composite outcome ‘overall success’. Single patient relevant endpoints such as pain, disability or quality of life improved in both groups with no superiority of CTDR. Both technologies showed similar complication rates. No evidence is available for the comparison between CTDR and non-surgical treatment. In the long run improvement of health outcomes seems to be similar in CTDR and fusion, however, the study quality is often severely limited. After both interventions, many patients still face problems. A difficulty per se is the correct diagnosis and indication for surgical interventions in the cervical spine. CTDR is no better than fusion in alleviating symptoms related to disc degeneration in the cervical spine. In the context of limited resources, a net cost comparison may be sensible. So far, CTDR is not recommended for routine use. As many trials are ongoing, re-evaluation at a later date will be required. Future research needs to address the relative effectiveness between CTDR and conservative treatment. PMID:20936484

  3. Long-term clinical results following Charite III lumbar total disc replacement.

    PubMed

    Lu, Shibao; Sun, Siyuan; Kong, Chao; Sun, Wenzhi; Hu, Hailiang; Wang, Qingyi; Hai, Yong

    2017-09-01

    The lumbar total disc replacement (TDR) operation represents an alternative to lumbar fusion for the treatment of symptomatic lumbar intervertebral disc degeneration, and has gained increasing attention in recent years. To assess clinical outcomes in a cohort of patients with TDR and the long-term survival rate of the prostheses. A retrospective, single-center clinical study. Thirty patients with a total of 35 prostheses after an average follow-up (FU) of 15.2 years following TDR, performed for the treatment of lumbar DDD. Clinical evaluation included visual analog scale (VAS) and the Oswestry disability index (ODI). Radiological parameters of intervertebral disc height (IDH), range of motion (ROM), lumbar lordosis (LL), lumbar scoliosis and prosthesis position were evaluated in surgical and adjacent levels. Complications and reoperation rates were also assessed. Clinical evaluation and radiological parameters were evaluated preoperatively and at final FU. All data was collected by members of our department including research assistants and nurses who were not involved in the decision-making of this study. Thirty of the 35 patients participated in the final FU. The cumulative survival rate of the prosthesis at a mean FU of 15.4 years was 100%. The clinical success rate was 93.3%. The VAS and ODI scores at final FU were significantly lower than preoperatively (P < 0.001). The average ROM of the operated and superior adjacent segment decreased significantly at the final FU, while the inferior adjacent segment was not affected. IDH of all surgical and adjacent levels were well maintained at the final FU. Ten patients had a lumbar scoliosis >3° and the mean angle was 8.5°, of which 7 had left convex curvature. Three prostheses were offset more than 5 mm from the midline on the coronal plane. Four prostheses showed subsidence. Twenty-six operative segments and 5 adjacent segments showed HO. Two patients of the complete 35 patients cohort underwent a secondary

  4. In vitro biomechanical comparison after fixed- and mobile-core artificial cervical disc replacement versus fusion.

    PubMed

    Lou, Jigang; Li, Yuanchao; Wang, Beiyu; Meng, Yang; Wu, Tingkui; Liu, Hao

    2017-10-01

    In vitro biomechanical analysis after cervical disc replacement (CDR) with a novel artificial disc prosthesis (mobile core) was conducted and compared with the intact model, simulated fusion, and CDR with a fixed-core prosthesis. The purpose of this experimental study was to analyze the biomechanical changes after CDR with a novel prosthesis and the differences between fixed- and mobile-core prostheses.Six human cadaveric C2-C7 specimens were biomechanically tested sequentially in 4 different spinal models: intact specimens, simulated fusion, CDR with a fixed-core prosthesis (Discover, DePuy), and CDR with a mobile-core prosthesis (Pretic-I, Trauson). Moments up to 2 Nm with a 75 N follower load were applied in flexion-extension, left and right lateral bending, and left and right axial rotation. The total range of motion (ROM), segmental ROM, and adjacent intradiscal pressure (IDP) were calculated and analyzed in 4 different spinal models, as well as the differences between 2 disc prostheses.Compared with the intact specimens, the total ROM, segmental ROM, and IDP at the adjacent segments showed no significant difference after arthroplasty. Moreover, CDR with a mobile-core prosthesis presented a little higher values of target segment (C5/6) and total ROM than CDR with a fixed-core prosthesis (P > .05). Besides, the difference in IDP at C4/5 after CDR with 2 prostheses was without statistical significance in all the directions of motion. However, the IDP at C6/7 after CDR with a mobile-core prosthesis was lower than CDR with a fixed-core prosthesis in flexion, extension, and lateral bending, with significant difference (P < .05), but not under axial rotation.CDR with a novel prosthesis was effective to maintain the ROM at the target segment and did not affect the ROM and IDP at the adjacent segments. Moreover, CDR with a mobile-core prosthesis presented a little higher values of target segment and total ROM, but lower IDP at the inferior adjacent segment

  5. Subsidence of SB Charité total disc replacement and the role of undersizing.

    PubMed

    Punt, Ilona; van Rijsbergen, Marc; van Rietbergen, Bert; Ito, Keita; van Rhijn, Lodewijk; van Ooij, André; Willems, Paul

    2013-10-01

    A possible complication after total disc replacement (TDR) is subsidence, presumably caused by asymmetric implantation, implant undersizing or reduced bone quality. This study aims to quantify the degree of subsidence of an SB Charité TDR, and investigate whether undersizing is related to subsidence. A custom developed software package (Mathworks) reconstructed 3D bone-implant geometry. A threshold for subsidence was determined by comparing penetrated bone volume (PBV) and rotation angles. Inter- and intra-observer reproducibilities were calculated. Subsidence was correlated to undersizing. High inter- and intra-observer correlation coefficients were found for the method (R > 0.92). Subsidence was quantified as PBV 700 mm(3) combined with a rotation angle >7.5°. A reduced risk of subsidence was correlated to >60 and >62 % of the bony endplate covered by the TDR endplate for L4 and L5, respectively. A reproducible method to determine undersizing was developed. Thresholds were determined related to a reduced risk of subsidence.

  6. Anhidrosis after anterior retroperitoneal approach for L4-L5 artificial disc replacement.

    PubMed

    Kasliwal, Manish K; Deutsch, Harel

    2011-07-01

    Description of injury to the sympathetic nervous system after the anterior approach to the lumbosacral spine remains restricted to reports of retrograde ejaculation in males occurring in 2% to 20% of patients. The authors describe a 46-year-old female who presented with low back pain for several years due to degenerative disk disease at L4-L5 that had been treated with an L4-L5 artificial disc replacement though a left anterior retroperitoneal approach. She has had an excellent outcome with complete resolution of her back pain, but noticed the development of dryness of her left lower limb with anhidrosis and skin breakdown, which has caused persistent discomfort. The complication had persisted at her 1-year follow up. Damage to the sympathetic system may often go unrecognized but present with subtle symptoms, as described in the present report. Sympathetic injury in women is often not addressed and remains unrecognized except for a few reports of vaginal dryness or anaesthesia. A short description of this unusual and underappreciated complication, which may be a cause of discomfort despite successful surgery, is presented.

  7. How to choose when implants of adjacent height both fit the disc space properly in single-level cervical artificial disc replacement.

    PubMed

    Rong, Xin; Lou, Jigang; Li, Huibo; Meng, Yang; Liu, Hao

    2017-07-01

    In cervical artificial disc replacement (C-ADR), sometimes we encountered with such cases that implants of adjacent height both fit the target disc space properly. No study was available discussing the choice of implant height and the clinical outcomes under such circumstance. The purpose of this study was to evaluate the impact of different implant heights on the clinical outcomes and radiographic results when the implants of adjacent height both fit the disc space properly. This retrospective study included 34 patients underwent single-level C-ADR at the C5-C6 level at our institution. In these 34 patients, implant with either 5 mm height or 6 mm height fit the surgical level properly without overstretching the disc space or the facet joint space. Clinical outcomes were evaluated using the Japanese Orthopedic Association score, visual analog scale (VAS), and Neck Disability Index. Radiographic assessments were conducted on static and dynamic radiographs for the determination of the disc space height, intersegmental range of motion (ROM), and the ROM of the functional spinal unit (FSU) at the surgical level. The baseline information of the patients, such as age, gender, weight, follow-up time, and diagnosis, was similar between the 2 groups (P > .05). Postoperative mean VAS in group B was significantly lower than that in group A (2.1 ± 0.7 vs. 2.7 ± 1.0, P < .05). The mean VAS decrease in group B was significantly larger than that in group A (5.3 ± 0.8 vs. 4.6 ± 1.1, P < .05). Significant difference was found in the postoperative disc height of the surgical segment between the 2 groups (6.4 ± 0.4 mm vs. 7.5 ± 0.5 mm, P < .05). No significant differences were noted in the intersegmental ROM and ROM of the FSU between the 2 groups both before the surgery and at the last follow-up (P > .05). No hypermobility or instability was observed in these patients. Our results suggested that when implants of adjacent

  8. Indications for Lumbar Total Disc Replacement: Selecting the Right Patient with the Right Indication for the Right Total Disc

    PubMed Central

    Guyer, Richard D.; Ohnmeiss, Donna D.

    2014-01-01

    Summary of Background Data As with any surgery, care should be taken to determine patient selection criteria for lumbar TDR based on safety and optimizing outcome. These goals may initially be addressed by analyzing biomechanical implant function and early clinical experience, ongoing evaluation is needed to refine indications. Objective The purpose of this work was to synthesize information published on general indications for lumbar TDR. A secondary objective was to determine if indications vary for different TDR designs. Methods A comprehensive literature search was conducted to identify lumbar TDR articles. Articles were reviewed and patient selection criteria and indications were synthesized. Results With respect to safety, there was good agreement in the literature to exclude patients with osteopenia/osteoporosis or fracture. Risk of injury to vascular structures due to the anterior approach was often addressed by excluding patients with previous abdominal surgery in the area of disc pathology or increased age. The literature was very consistent on the primary indication for TDR being painful disc degeneration unresponsive to at least 6 months of nonoperative care. Literature investigating the impact of previous spine surgery was mixed; however, prior surgery was not necessarily a contra-indication, provided the patient otherwise met selection criteria. The literature was mixed on setting a minimum preoperative disc height as a selection criterion. There were no publications investigating whether some patients are better/worse candidates for specific TDR designs. Based on the literature a proposal for patient selection criteria is offered. Conclusions Several TDR indications and contra-indications are widely accepted. No literature addresses particular TDR design being preferable for some patients. As with any spine surgery, ongoing evaluation of TDR outcomes will likely lead to more detailed general and device design specific indications. PMID:25694946

  9. UHMWPE wear debris and tissue reactions are reduced for contemporary designs of lumbar total disc replacements.

    PubMed

    Veruva, Sai Y; Lanman, Todd H; Isaza, Jorge E; MacDonald, Daniel W; Kurtz, Steven M; Steinbeck, Marla J

    2015-03-01

    Lumbar total disc replacement (L-TDR) is a procedure used to relieve back pain and maintain mobility. Contemporary metal-on-polyethylene (MoP) L-TDRs were developed to address wear performance concerns about historical designs, but wear debris generation and periprosthetic tissue reactions for these newer implants have not been determined. The purpose of this study was to determine (1) whether periprosthetic ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris and biological responses were present in tissues from revised contemporary MoP L-TDRs that contain conventional cores fabricated from γ-inert-sterilized UHMWPE; (2) how fixed- versus mobile-bearing design affected UHMWPE wear particle number, shape, and size; and (3) how these wear particle characteristics compare with historical MoP L-TDRs that contain cores fabricated from γ-air-sterilized UHMWPE. We evaluated periprosthetic tissues from 11 patients who received eight fixed-bearing ProDisc-L and four mobile-bearing CHARITÉ contemporary L-TDRs with a mean implantation time of 4.1 and 2.7 years, respectively. Histologic analysis of tissues was performed to assess biological responses and polarized light microscopy was used to quantify number and size/shape characteristics of UHMWPE wear particles from the fixed- and mobile-bearing devices. Comparisons were made to previously reported particle data for historical L-TDRs. Five of seven (71%) fixed-bearing and one of four mobile-bearing L-TDR patient tissues contained at least 4 particles/mm(2) wear with associated macrophage infiltration. Tissues with wear debris were highly vascularized, whereas those without debris were more necrotic. Given the samples available, the tissue around mobile-bearing L-TDR was observed to contain 87% more, 11% rounder, and 11% less-elongated wear debris compared with tissues around fixed-bearing devices; however, there were no significant differences. Compared with historical L-TDRs, UHMWPE particle number and

  10. Total lumbar disc replacement in athletes: clinical results, return to sport and athletic performance

    PubMed Central

    Wiechert, Karsten; Khattab, Mohamed F.; Korge, Andreas; Mayer, H. Michael

    2007-01-01

    Despite the increasing popularity of total lumbar disc replacement (TDR) in predominantly young and active patients, no previous study has addressed possibilities, limitations and potential risks regarding athletic performance following TDR. Mechanical concerns remain and the implant’s resilience as regards its load-bearing capacity during sporting activities is unknown. Thirty-nine athletic patients fulfilled the inclusion criteria for this study. These patients participated in a large variety of different types of sport. Significant and lasting pain-relief was attained following TDR with a mean follow-up of 26.3 months (range 9–50.7 months; FU rate 97.4%). Sporting activity was resumed within the first 3 months (38.5%) to 6 months (30.7%) with peak performance being reached after 5.2 months. Thirty-seven patients (94.9%) achieved resumption of sporting activity. Athletic performance improved significantly in 33 patients (84.6%). Minor subsidence was observed in 13 patients (30%) within the first 3 months with no further implant migration thereafter in 12 patients. Participation in all types of sport recorded in this study was accessible for a high rate of patients up to the level of professional athletes as well as those participating in extreme sports. Preoperative participation in sport proved to be a strong positive predictor for highly satisfactory postoperative outcome following TDR. In a selected group of patients, however, preoperative inability to participate in sporting activities did not impair postoperative physical activity. Due to the young age of the patients and significant load increase exerted during athletic activities, persisting concerns regarding the future behaviour of the implant remain and will require longer follow-up, modified investigation techniques and larger patient cohorts. PMID:17205239

  11. Total lumbar disc replacement in athletes: clinical results, return to sport and athletic performance.

    PubMed

    Siepe, Christoph J; Wiechert, Karsten; Khattab, Mohamed F; Korge, Andreas; Mayer, H Michael

    2007-07-01

    Despite the increasing popularity of total lumbar disc replacement (TDR) in predominantly young and active patients, no previous study has addressed possibilities, limitations and potential risks regarding athletic performance following TDR. Mechanical concerns remain and the implant's resilience as regards its load-bearing capacity during sporting activities is unknown. Thirty-nine athletic patients fulfilled the inclusion criteria for this study. These patients participated in a large variety of different types of sport. Significant and lasting pain-relief was attained following TDR with a mean follow-up of 26.3 months (range 9-50.7 months; FU rate 97.4%). Sporting activity was resumed within the first 3 months (38.5%) to 6 months (30.7%) with peak performance being reached after 5.2 months. Thirty-seven patients (94.9%) achieved resumption of sporting activity. Athletic performance improved significantly in 33 patients (84.6%). Minor subsidence was observed in 13 patients (30%) within the first 3 months with no further implant migration thereafter in 12 patients. Participation in all types of sport recorded in this study was accessible for a high rate of patients up to the level of professional athletes as well as those participating in extreme sports. Preoperative participation in sport proved to be a strong positive predictor for highly satisfactory postoperative outcome following TDR. In a selected group of patients, however, preoperative inability to participate in sporting activities did not impair postoperative physical activity. Due to the young age of the patients and significant load increase exerted during athletic activities, persisting concerns regarding the future behaviour of the implant remain and will require longer follow-up, modified investigation techniques and larger patient cohorts.

  12. Adjacent segment degeneration following ProDisc-C total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF): does surgeon bias effect radiographic interpretation?

    PubMed

    Laxer, Eric B; Brigham, Craig D; Darden, Bruce V; Bradley Segebarth, P; Alden Milam, R; Rhyne, Alfred L; Odum, Susan M; Spector, Leo R

    2017-04-01

    Many investigators have reported the financial conflicts of interest (COI), which could result in potential bias in the reporting of outcomes for patients undergoing total disc replacement (TDR) rather than anterior cervical discectomy and fusion (ACDF). This bias may be subconsciously introduced by the investigator in a non-blinded radiographic review. The purpose of this study was to determine if bias was present when a group of spine specialists rated adjacent segment degeneration (ASD) following cervical TDR or ACDF. Potential bias in the assessment of ASD was evaluated through the reviews of cervical radiographs (pre- and 6 years post-operative) from patients participating in the ProDisc-C FDA trial (ProDisc-C IDE #G030059). The index level was blinded on all radiographs during the first review, but unblinded in the second. Five reviewers (a radiologist, two non-TDR surgeons, and two TDR surgeons), two of whom had a COI with the ProDisc-C trial sponsor, assessed ASD on a three point scale: yes, no, or unable to assess. Intra- and inter-rater reliabilities between all raters were assessed by the Kappa statistic. The intra-rater reliability between reviews was substantial, indicating little to no bias in assessing ASD development/progression. The Kappa statistics were 0.580 and 0.644 for the TDR surgeons (p < 0.0001), 0.718 and 0.572 for the non-TDR surgeons (p < 0.0001), and 0.642 for the radiologist (p < 0.0001). Inter-rater reliability for the blinded review ranged from 0.316 to 0.607 (p < 0.0001) and from 0.221 to 0.644 (p < 0.0001) for the unblinded review. The knowledge of the surgical procedure performed did not bias the assessment of ASD.

  13. Biomechanical Analysis of a Novel Prosthesis Based on the Physiological Curvature of Endplate for Cervical Disc Replacement

    PubMed Central

    Yu, Cheng-Cheng; Hao, Ding-Jun; Huang, Da-Geng; Qian, Li-Xiong; Feng, Hang; Li, Hou-Kun; Zhao, Song-Chuan

    2016-01-01

    Study Design Biomechanical analysis of a novel prosthesis based on the physiological curvature of endplate was performed. Objective To compare the biomechanical differences between a novel prosthesis based on the physiological curvature of the endplate and the Prestige LP prosthesis after cervical disc replacement (CDR). Summary of Background Data Artificial disc prostheses have been widely used to preserve the physiological function of treated and adjacent motion segments in CDR, while most of those present a flat surface instead of an arcuate surface which approximately similar to anatomic structures in vivo. We first reported a well-designed artificial disc prosthesis based on the physiological curvature of the endplate. Methods Three motion segments of 24 ovine cervical spines (C2-5) were evaluated in a robotic spine system with axial compressive loads of 50N. Testing conditions were as follows: 1) intact, 2) C3–4 CDR with artificial disc prosthesis based on the physiological curvature of the endplate, and 3) C3–4 CDR with the Prestige LP prosthesis. The range of motion (ROM) and the pressures on the inferior surface of the two prostheses were recorded and analyzed. Results As compared to the intact state, the ROM of all three segments had no significant difference in the replacement group. Additionally, there was no significant difference in ROM between the two prostheses. The mean pressure on the novel prosthesis was significantly less than the Prestige LP prosthesis. Conclusion ROM in 3 groups (intact group, CDR group with novel prosthesis and CDR group with Prestige LP) showed no significant difference. The mean pressure on the inferior surface of the novel prosthesis was significantly lower than the Prestige LP prosthesis. Therefore, the novel artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface pressure on the endplate, which may be one possible reason of prosthesis subsidence. PMID:27355319

  14. Biomechanical Analysis of a Novel Prosthesis Based on the Physiological Curvature of Endplate for Cervical Disc Replacement.

    PubMed

    Yu, Cheng-Cheng; Hao, Ding-Jun; Huang, Da-Geng; Qian, Li-Xiong; Feng, Hang; Li, Hou-Kun; Zhao, Song-Chuan

    2016-01-01

    Biomechanical analysis of a novel prosthesis based on the physiological curvature of endplate was performed. To compare the biomechanical differences between a novel prosthesis based on the physiological curvature of the endplate and the Prestige LP prosthesis after cervical disc replacement (CDR). Artificial disc prostheses have been widely used to preserve the physiological function of treated and adjacent motion segments in CDR, while most of those present a flat surface instead of an arcuate surface which approximately similar to anatomic structures in vivo. We first reported a well-designed artificial disc prosthesis based on the physiological curvature of the endplate. Three motion segments of 24 ovine cervical spines (C2-5) were evaluated in a robotic spine system with axial compressive loads of 50N. Testing conditions were as follows: 1) intact, 2) C3-4 CDR with artificial disc prosthesis based on the physiological curvature of the endplate, and 3) C3-4 CDR with the Prestige LP prosthesis. The range of motion (ROM) and the pressures on the inferior surface of the two prostheses were recorded and analyzed. As compared to the intact state, the ROM of all three segments had no significant difference in the replacement group. Additionally, there was no significant difference in ROM between the two prostheses. The mean pressure on the novel prosthesis was significantly less than the Prestige LP prosthesis. ROM in 3 groups (intact group, CDR group with novel prosthesis and CDR group with Prestige LP) showed no significant difference. The mean pressure on the inferior surface of the novel prosthesis was significantly lower than the Prestige LP prosthesis. Therefore, the novel artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface pressure on the endplate, which may be one possible reason of prosthesis subsidence.

  15. Comparison between single- and multi-level patients: clinical and radiological outcomes 2 years after cervical disc replacement.

    PubMed

    Huppert, J; Beaurain, J; Steib, J P; Bernard, P; Dufour, T; Hovorka, I; Stecken, J; Dam-Hieu, P; Fuentes, J M; Vital, J M; Vila, T; Aubourg, L

    2011-09-01

    In cervical multi-level degenerative pathology, considering the morbidity of the extensive fusion techniques, some authors advocate for the multilevel disc replacement. This study compared the safety and efficacy of disc replacement with an unconstrained prosthesis in multi- versus single-level patients. A total of 231 patients with cervical degenerative disc disease (DDD) who were treated with cervical disc replacement and completed their 24 months follow-up were analyzed prospectively: 175 were treated at one level, 56 at 2 levels or more. Comparison between both groups was based on usual clinical and radiological outcomes [Neck Disability Index (NDI), Visual Analog Scale (VAS), Range of Motion, satisfaction]. Safety assessments, including complication and subsequent surgeries, were also documented and compared. Mean NDI and VAS scores for neck and arm pain were improved in both groups similarly. Improvement of mobility at treated segments was also similar. Nevertheless, in the multi-level group, analgesic use was significantly higher and occurrence of Heterotopic Ossification significantly lower than in the single-level group. Subject satisfaction was nearly equal, as 94.2% of single-level group patients would undergo the surgery again versus 94.5% in the multi-level group. The overall success rate did not differ significantly. Multi-level DDD is a challenging indication in the cervical spine. This study showed no major significant clinical difference between the two groups. We need further studies to know more about the impact of multi-level arthroplasty, especially on the adjacent segments, but these results demonstrate initial safety and effectiveness in this patient sample.

  16. 342 Lumbar Total Disc Replacement by the Lateral Approach Up to 10-Year Follow-up.

    PubMed

    Pimenta, Luiz; Marchi, Luis; Amaral, Rodrigo Augusto; Oliveira, Leonardo; Nogueira-Neto, Joes; Jensen, Rubens; Coutinho, Etevaldo

    2016-08-01

    improved physical function for patient with the disc. Lumbar artificial disc replacement done by the lateral approach seems to be a feasible effective treatment for mild degenerative disc disease.

  17. Biomechanics of Hybrid Anterior Cervical Fusion and Artificial Disc Replacement in 3-Level Constructs: An In Vitro Investigation

    PubMed Central

    Liao, Zhenhua; Fogel, Guy R.; Pu, Ting; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    Background The ideal surgical approach for cervical disk disease remains controversial, especially for multilevel cervical disease. The purpose of this study was to investigate the biomechanics of the cervical spine after 3-level hybrid surgery compared with 3-level anterior cervical discectomy and fusion (ACDF). Material/Methods Eighteen human cadaveric spines (C2-T1) were evaluated under displacement-input protocol. After intact testing, a simulated hybrid construct or fusion construct was created between C3 to C6 and tested in the following 3 conditions: 3-level disc plate disc (3DPD), 3-level plate disc plate (3PDP), and 3-level plate (3P). Results Compared to intact, almost 65~80% of motion was successfully restricted at C3-C6 fusion levels (p<0.05). 3DPD construct resulted in slight increase at the 3 instrumented levels (p>0.05). 3PDP construct resulted in significant decrease of ROM at C3-C6 levels less than 3P (p<0.05). Both 3DPD and 3PDP caused significant reduction of ROM at the arthrodesis level and produced motion increase at the arthroplasty level. For adjacent levels, 3P resulted in markedly increased contribution of both upper and lower adjacent levels (p<0.05). Significant motion increases lower than 3P were only noted at partly adjacent levels in some conditions for 3DPD and 3PDP (p<0.05). Conclusions ACDF eliminated motion within the construct and greatly increased adjacent motion. Artificial cervical disc replacement normalized motion of its segment and adjacent segments. While hybrid conditions failed to restore normal motion within the construct, they significantly normalized motion in adjacent segments compared with the 3-level ACDF condition. The artificial disc in 3-level constructs has biomechanical advantages compared to fusion in normalizing motion. PMID:26529430

  18. [Influence of intraoperative cervical posture in single segmental cervical disc replacement on restoration of cervical curve in neutral position].

    PubMed

    Hong, Ying; Deng, Yuxiao; Liu, Hao; Gong, Renrong; An, Lingjing; Gong, Quan; Li, Tao; Song, Yueming

    2013-01-01

    To study the correlation between the cervical posture in the cervical disc replacement (CDR). Between January 2008 and August 2010, 51 and the cervical curve restoration in neutral position after surgery. patients underwent single segmental PRESTIGE LP replacement, and the clinical data were retrospectively analyzed. During the surgery, the patient was supinely placed and the lordosis of the cervical spine was mantained with a pillow placed beneath the neck. Of them, 28 were male and 23 were female, aged 30-64 years (mean, 45 years); 32 were diagnosed as having cervical spondylotic myelopathy, 7 having radiculopathy, and 12 having myelopathy and radiculopathy. The disease duration was 3-48 months (mean, 15 months). CDR was performed at C(4, 5) in 5 cases, at C(5, 6) in 42 cases, and at C(6, 7) in 4 cases. The Cobb angles of the cervical alignment, targeted functional spinal unit (FSU), and targeted disc were measured by sagittal X-ray film of the cervical spine in neutral position before and after surgery, as well as the intraoperative C-arm fluroscopy of the cervical spine. Linear correlation and regression were performed to analyze the relation between cervical Cobb angle difference at intraoperation and improvement of the Cobb angles at 3 months after operation. The cervical Cobb angles at intraoperation and 3 months after operation were larger than those at preoperation (P < 0.05). The difference of the Cobb angle between intra- and pre-operation was (6.72 +/- 9.13) degrees on cervical alignment, (2.10 +/- 5.12) degrees on targeted FSU, and (3.33 +/- 3.75) degrees on targeted disc. At 3 months after operation, the Cobb angle improvement of the cervical alignment, targeted FSU, and targeted disc was (6.30 +/- 7.28), (3.99 +/- 5.37), and (4.29 +/- 5.36) degrees, respectively. There was no significant difference in the Cobb angle improvement between the targeted FSU and the targeted disc (t = -4.391, P = 0.698), and between the targeted disc and the cervical

  19. Significance of angular mismatch between vertebral endplate and prosthetic endplate in lumbar total disc replacement.

    PubMed

    Lee, Chong Suh; Chung, Sung Soo; Oh, Sung Kyun; You, Je Wook

    2011-05-01

    A retrospective study. To determine whether angular mismatch between the vertebral endplate and prosthetic endplate during lumbar total disc replacement (L-TDR) affects the radiological and clinical outcomes. A prosthesis anchored to the vertebral body by using a large central keel carries an inherent risk of angular mismatch between the vertebral endplate and prosthetic endplate at a segment with a greater degree of lordosis, such as L5-S1. Theoretically, this angular mismatch can cause several problems, such as segmental hyperlordosis, anterior positioning of the upper prosthesis, posterior prosthetic edge subsidence, decreased range of motion (ROM), and a poor clinical outcome. This study evaluated 64 prosthetic levels of 56 patients who were implanted with L-TDR between June 2002 and February 2006. There were 38 and 26 prosthetic levels at the L4-5 and L5-S1, respectively. The mean follow-up period was 25.6 (12 to 49) months. The angle of mismatch between the lower endplate of the upper vertebral body and the upper prosthetic plate, segmental flexion/extension ROM, segmental lordosis angle at extension, distance from the posterior wall of the vertebral body to the posterior prosthetic edge were measured by obtaining radiographs. Clinically, the Visual Analogue Scale and Oswestry Disability Index were also evaluated. The angular mismatches between the upper vertebra and prosthesis at L4-5 and L5-S1 were 1.6 degree and 5.6 degree, respectively (P <0.001), at the final follow-up; these angles were not significantly different from those measured on radiographs obtained postoperatively (2.3 degree and 4.9 degree in L4-5 and L5-S1, respectively, P=0.324 in L4-5 and P=0.620 in L5-S1). The mean segmental ROM of the operated levels was 10.6 degree (4 to 22) and 6.1 degree (2 to 13) in the L4-5 and L5-S1, respectively (P <0.001). The mean segmental ROM, mean segmental lordosis angle, and mean distance from the posterior margin of the vertebral body to the posterior edge

  20. A Broken Drill-bit Fragment Causing Severe Radiating Pain after Cervical Total Disc Replacement: A Case Report.

    PubMed

    Lee, Chong-Suh; Chung, Sung-Soo; Park, Jae-Chul; Shin, Seong-Kee; Park, Yong-Serk; Kang, Kyung-Chung

    2011-06-01

    This is a case report of a 38-year-old man with severe radiating pain on upper extremity after cervical total disc replacement (TDR). We faced an unusual complication that has not been reported yet. He underwent cervical TDR for left central disc protrusion on C5-6. After the surgery, preoperative symptom disappeared. However, at postoperative 1 year, he complained severe right-sided radiating pain that had a sudden onset. On postoperative X-ray, a metal fragment which seemed like a broken drill bit was shown within the spinal canal. To remove that, right-sided anterior microforaminotomy on C5-6 was performed and the metal fragment was removed successfully. After that, anterior fusion was done because the motion of the artificial disc was minimal and the removed structure seemed to attenuate stability during cervical motion. The operation resulted in prompt symptomatic relief. During cervical TDR, particular attention should be paid to the procedures that require using drill-bits.

  1. Prosthetic Valve Dysfunction 35 Years after Mitral Valve Replacement with a Starr-Edwards Caged-disc Valve.

    PubMed

    Yokokawa, Tetsuro; Ohara, Takahiro; Takashio, Seiji; Sakamoto, Mari; Wada, Yuko; Nakamura, Kenji; Takahama, Hiroyuki; Amaki, Makoto; Hasegawa, Takuya; Sugano, Yasuo; Kanzaki, Hideaki; Yasuda, Satoshi; Ogawa, Hisao; Fujita, Tomoyuki; Kobayashi, Junjiro; Okamoto, Yoko; Matsuyama, Taka-Aki; Ishibashi-Ueda, Hatsue; Anzai, Toshihisa

    2016-01-01

    A 49-year-old man was admitted to our hospital with a chief complaint of dyspnea. He had a history of mitral valve replacement (MVR) with a Starr-Edwards (SE) caged-disc valve at the age of 14. Echocardiography revealed elevated trans-valvular pressure gradient of the mitral prosthetic valve with neither disk motion abnormality nor abnormal structure. Catheterization confirmed an elevation of the mean diastolic gradient of the mitral valve to 12.3 mmHg. Re-MVR was performed, and abnormal tissue attached to the cage of the valve and proliferating beneath the valve was observed. Histologic examination revealed them as fibrinous tissue and mild pannus proliferation, respectively. This rare case report focuses on long-term follow-up and the complication of a SE caged-disc valve. A SE caged-disc valve may become stenotic, only detected with a trans-valvular pressure gradient without any disk motion abnormality or abnormal structure during a prolonged follow-up period.

  2. Kinematic evaluation of one- and two-level Maverick lumbar total disc replacement caudal to a long thoracolumbar spinal fusion.

    PubMed

    Zhu, Qingan; Itshayek, Eyal; Jones, Claire F; Schwab, Timothy; Larson, Chadwick R; Lenke, Lawrence G; Cripton, Peter A

    2012-06-01

    Adjacent level degeneration that occurs above and/or below long fusion constructs is a documented clinical problem that is widely believed to be associated with the considerable change in stiffness caused by the fusion. Some researchers have suggested that early degeneration at spinal joints adjacent to a fusion could be treated by implanting total disc replacements at these levels. It is thought that further degeneration could be prevented through the disc replacement's design aims to reproduce normal disc heights, kinematics and tissue loading. For this reason, there is a clinical need to evaluate if a total disc replacement can maintain both the quantity of motion (i.e. range) and the quality of motion (i.e. center of rotation and coupling) at segments adjacent to a long spinal fusion. The purpose of this study was to experimentally evaluate range of motion (ROM-the intervertebral motion measured) and helical axis of motion (HAM) changes due to one- and two-level Maverick total disc replacement (TDR) adjacent to a long spinal fusion. Seven spine specimens (T8-S1) were used in this study (66 ± 19 years old, 3F/4 M). A continuous pure moment of ±5.0 Nm was applied to the specimen in flexion-extension (FE), lateral bending (LB) and axial rotation (AR), with a compressive follower preload of 400 N. The 5.0 Nm data were analyzed to evaluate the operated segment biomechanics at the level of the disc replacements. The data were also analyzed at lower moments using a modified version of Panjabi's proposed "hybrid" method to evaluate adjacent segment kinematics (intervertebral motion at the segments adjacent to the fusion) under identical overall (T8-S1) specimen rotations. The motion of each vertebra was monitored with an optoelectronic camera system. The biomechanical test was completed for (1) the intact condition and repeated after each surgical technique was applied to the specimen, (2) capsulotomy at L4-L5 and L5-S1, (3) T8-L4 fusion and capsulotomy at L4

  3. Harken Caged-Disc Mitral Valve Replacement, 1969-1975: Analysis of Late Mortality, Thromboembolism, and Valve Failure

    PubMed Central

    Gray, Richard J.; Czer, Lawrence S.C.; Chaux, Aurelio; Sethna, Dhun; Derobertis, Michele; Raymond, Marjorie; Matloff, Jack M.

    1987-01-01

    We evaluated the long-term outcome of mitral valve replacement with a Harken caged-disc prosthesis for up to 11 years (range, 50 to 130 months; mean, 81 months) in 170 patients whose mean age was 55 years. The early (30-day) mortality was 11.2% (19 out of 170 patients). Late follow-up information was obtained for 144 (95%) of the 151 survivors. The actuarial survival was 57% at 5 years and 40% at 10 years. Overall mortality was associated with advanced age, male sex, an ischemic origin for the mitral valve disease, and nonuse of warfarin anticoagulation. Late deaths (n=59) were valve-related in 46%, cardiac but non-valve-related in 44%, and noncardiac in 10% of the cases. One thromboembolic event or more occurred in 41 patients (incidence, 5.7% per patient year), 14 of whom died (24% of the late deaths). All four patients who were not on warfarin, aspirin, or other antithrombotic therapy experienced thromboemboli. This complication was correlated with the nonuse of warfarin-type anticoagulation, with mitral regurgitation, and with late cardiac death. Mechanical prosthetic failure resulted in reoperation or death in 7.6% of the late survivors (1.5% per patient year). In 75 patients with normally functioning prostheses, the disc-to-sewing ring ratio was established by means of cinefluoroscopy (0.93 ± 0.04, mean ± 25D). Because of the high proportion of cardiac valve-related deaths (46%), the high incidence of late mortality due to thromboembolic events (24%), and the 7.6% incidence of reoperation or death resulting from mechanical valve failure, close follow-up with cinefluoroscopy and continued warfarin anticoagulation (alone or in combination with dipyridamole) are essential after mitral valve replacement with the Harken caged-disc prosthesis. (Texas Heart Institute Journal 1987; 14:411-417) Images PMID:15227298

  4. Cervical Total Disc Replacement is Superior to Anterior Cervical Decompression and Fusion: A Meta-Analysis of Prospective Randomized Controlled Trials

    PubMed Central

    Zhang, Yujie; Liang, Chengzhen; Tao, Yiqing; Zhou, Xiaopeng; Li, Hao; Li, Fangcai; Chen, Qixin

    2015-01-01

    Background Despite being considered the standard surgical procedure for symptomatic cervical disc disease, anterior cervical decompression and fusion invariably accelerates adjacent segment degeneration. Cervical total disc replacement is a motion-preserving procedure developed as a substitute to fusion. Whether cervical total disc replacement is superior to fusion remains unclear. Methods We comprehensively searched PubMed, EMBASE, Medline, and the Cochrane Library in accordance with the inclusion criteria to identify possible studies. The retrieved results were last updated on December 12, 2014. We classified the studies as short-term and midterm follow-up. Results Nineteen randomized controlled trials involving 4516 cases were identified. Compared with anterior cervical decompression and fusion, cervical total disc replacement had better functional outcomes (neck disability index [NDI], NDI success, neurological success, neck pain scores reported on a numerical rating scale [NRS], visual analog scales scores and overall success), greater segmental motion at the index level, fewer adverse events and fewer secondary surgical procedures at the index and adjacent levels in short-term follow-up (P < 0.05). With midterm follow-up, the cervical total disc replacement group indicated superiority in the NDI, neurological success, pain assessment (NRS), and secondary surgical procedures at the index level (P < 0.05). The Short Form 36 (SF-36) and segmental motion at the adjacent level in the short-term follow-up showed no significant difference between the two procedures, as did the secondary surgical procedure rates at the adjacent level with midterm follow-up (P > 0.05). Conclusions Cervical total disc replacement presented favorable functional outcomes, fewer adverse events, and fewer secondary surgical procedures. The efficacy and safety of cervical total disc replacement are superior to those of fusion. Longer-term, multicenter studies are required for a better

  5. Five-year clinical results of cervical total disc replacement compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled, multicenter investigational device exemption clinical trial.

    PubMed

    Radcliff, Kris; Coric, Domagoj; Albert, Todd

    2016-08-01

    OBJECTIVE The purpose of this study was to report the outcome of a study of 2-level cervical total disc replacement (Mobi-C) versus anterior cervical discectomy and fusion (ACDF). Although the long-term outcome of single-level disc replacement has been extensively described, there have not been previous reports of the 5-year outcome of 2-level cervical disc replacement. METHODS This study reports the 5-year results of a prospective, randomized US FDA investigational device exemption (IDE) study conducted at 24 centers in patients with 2-level, contiguous, cervical spondylosis. Clinical outcomes at up to 60 months were evaluated, including validated outcome measures, incidence of reoperation, and adverse events. The complete study data and methodology were critically reviewed by 3 independent surgeon authors without affiliation with the IDE study or financial or institutional bias toward the study sponsor. RESULTS A total of 225 patients received the Mobi-C cervical total disc replacement device and 105 patients received ACDF. The Mobi-C and ACDF follow-up rates were 90.7% and 86.7%, respectively (p = 0.39), at 60 months. There was significant improvement in all outcome scores relative to baseline at all time points. The Mobi-C patients had significantly more improvement than ACDF patients in terms of Neck Disability Index score, SF-12 Physical Component Summary, and overall satisfaction with treatment at 60 months. The reoperation rate was significantly lower with Mobi-C (4%) versus ACDF (16%). There were no significant differences in the adverse event rate between groups. CONCLUSIONS Both cervical total disc replacement and ACDF significantly improved general and disease-specific measures compared with baseline. However, there was significantly greater improvement in general and disease-specific outcome measures and a lower rate of reoperation in the 2-level disc replacement patients versus ACDF control patients. Clinical trial registration no. NCT00389597

  6. Clinical results of Maverick lumbar total disc replacement: two-year prospective follow-up.

    PubMed

    Le Huec, J C; Mathews, H; Basso, Y; Aunoble, S; Hoste, D; Bley, B; Friesem, T

    2005-07-01

    Disc prosthesis is the new treatment for degenerative disc disease in the lumbar spine. Key to assessing the interest in this new motion technique is evaluating the results in terms of functional and radiologic outcomes. This prospective study reports the outcome of 64 Maverick devices implanted between January 2002 and November 2003. The degree of improvement was equivalent to that obtained with anterior fusion cages using the mini-invasive technique. Radiographic follow-up in this series showed a degree of mobility close to normal. The technique is safe because the intra- and postoperative complication rate is low. The Oswestry score improved for 75% of patients. This improvement is significantly correlated with facet arthrosis and muscle fatty degeneration.

  7. Clinical outcome of monosegmental total disc replacement for lumbar disc disease with ball-and-socket prosthesis (Maverick): prospective study with four-year follow-up.

    PubMed

    Van de Kelft, Erik; Verguts, Leo

    2012-01-01

    Arthrodesis is considered to be the reference treatment for degenerative disc disease (DDD), if the symptoms are refractory to conservative management. The drawback of arthrodesis is, besides a percentage of non-union, the reduced mobility that might generate an increased load and risk for degeneration of the adjacent levels. Total disc replacement (TDR) implants may overcome this problem. The long-term clinical effect and radiographic evaluation of motion preservation after implantation, however, have been subject to several nonconclusive studies. This study evaluated the long-term clinical and radiographic results and the safety of TDR with the Maverick prosthesis for surgical treatment of monosegmental DDD. TDR was performed in 50 consecutive patients with monosegmental DDD using the Maverick device. Patients were followed prospectively for disability, quality of life, pain intensity and frequency, as well as working status and return to sports, during 48 months. Motion preservation was assessed on neutral and dynamic radiographs at 48 months. The disability, pain intensity and frequency, and quality of life improved significantly at the 6-week follow-up, which was maintained over the full 48 months following Maverick implantation. Preoperatively, 80% of the patients stopped working and 86% halted sports activities. Four years after surgery, 85% of patients were again working and 79% took up their normal sports activities. Radiographic assessment showed that motion at the index level is maintained 48 months after TDR. No major complications were encountered. In this study, TDR with the Maverick prosthesis at one lumbar segment reduced pain and disability and improved quality of life as well as the general condition. Motion was preserved at the operated level, 48 months after surgery. The long-term effect on adjacent levels needs further follow-up. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Clinical and radiologic comparison of dynamic cervical implant arthroplasty and cervical total disc replacement for single-level cervical degenerative disc disease.

    PubMed

    Shichang, Liu; Yueming, Song; Limin, Liu; Lei, Wang; Zhongjie, Zhou; Chunguang, Zhou; Xi, Yang

    2016-05-01

    Anterior cervical discectomy and fusion, to date the most successful spine procedure for the surgical treatment of cervical radiculopathy, has limitations that have led to the development of non-fusion cervical procedures, such as cervical total disc replacement (TDR) and dynamic cervical implant (DCI) arthroplasty. We compared the clinical and radiological results of DCI and cervical TDR for the treatment of single-level cervical degenerative disc disease in Chinese patients. A retrospective review of 179 patients with cervical spondylotic myelopathy who underwent DCI or TDR between April 2010 and October 2012 was conducted, and 152 consecutive patients (67 patients single-level DCI and 85 single-level TDR) who completed at least 2years of follow-up were included. Clinical and radiological assessments were performed preoperatively and at 1week and 3, 6, 12, and 24months postoperatively. The most common operative level was C5/C6 (49.3%). The differences in blood loss, duration of surgery, and duration of hospitalization were not statistically significant. The Japanese Orthopaedic Association scale, Visual Analog Scale, Neck Disability Index, and Short Form-36 scores improved significantly after surgery in both the DCI and TDR groups (P<0.05), but the differences were not statistically significant at the final follow-up. The rate of occurrence of heterotopic ossification was 22.4% and 28.2% in the DCI and TDR groups, respectively. As an effective non-fusion technique, DCI is a more economical procedure. Further prospective, randomized studies with long-term follow-up periods are needed to determine the long-term effects.

  9. Positive Pitfalls

    ERIC Educational Resources Information Center

    Schneider, Michael

    2004-01-01

    This article describes how Cahokia middle and high school students conduct inquiry-based science through a pitfall trap experiment. In a collaborative effort, students designed and conducted pitfall trap investigations that combined their interest in the natural world with their love of technology. The students set up their own experiments to…

  10. Positive Pitfalls

    ERIC Educational Resources Information Center

    Schneider, Michael

    2004-01-01

    This article describes how Cahokia middle and high school students conduct inquiry-based science through a pitfall trap experiment. In a collaborative effort, students designed and conducted pitfall trap investigations that combined their interest in the natural world with their love of technology. The students set up their own experiments to…

  11. Health-related quality of life in patients undergoing lumbar total disc replacement: A comparison with the general population.

    PubMed

    Clavel, Pablo; Ungureanu, Gheorghe; Catalá, Ignasi; Montes, Guillermo; Málaga, Xavier; Ríos, Moisés

    2017-09-01

    In up to half of the cases, low back pain (LBP) is thought to be related to a degeneration of the lumbar disc. Lumbar total disc replacement (LTDR) emerged as an alternative to fusion, but its use and indications are still subject to debate. The purpose of this paper was to compare Health-related Quality of life (HRQOL) in patients undergoing LTDR for one or two-level degenerative disc disease (DDD) with the paired age and gender general population values and to assess functional disability and residual pain at one year after the surgical procedure. A series of 51 patients operated on for a one or two level DDD, were evaluated at one year after the surgical procedure. HRQOL was compared to that of paired age and gender general population using the EQ-5D-5L questionnaire. Disability, back (BP) and leg pain (LP) were compared to the preoperative values. ODI showed a mean improvement of 31.78 (p<0.001, 95% CI 27.39-36.17), BP-VAS of 5.29/10 (95% CI 4.56-6.02), LP-VAS of 4.03/10 (95% CI 3.15-4.92) at one year compared to the preoperative assessment. HRQOL had similar values to the general population in 32 patients and inferior in 19 patients. "Pain" was the HRQOL dimension in which most of the patients had inferior results compared to data from the general population. Patients with previous spinal surgery had lower improvements in HRQOL index, disability, and pain than those without previous surgery. We found that the majority of patients improved their HQOL to values similar to those of the general population. Disability and pain are significantly reduced compared to preoperative evaluations. Larger scale studies are needed to identify the best candidates for LTDR. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Biomechanics of Artificial Disc Replacements Adjacent to a 2-Level Fusion in 4-Level Hybrid Constructs: An In Vitro Investigation

    PubMed Central

    Liao, Zhenhua; Fogel, Guy R.; Wei, Na; Gu, Hongsheng; Liu, Weiqiang

    2015-01-01

    Background The ideal procedure for multilevel cervical degenerative disc diseases remains controversial. Recent studies on hybrid surgery combining anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR) for 2-level and 3-level constructs have been reported in the literature. The purpose of this study was to estimate the biomechanics of 3 kinds of 4-level hybrid constructs, which are more likely to be used clinically compared to 4-level arthrodesis. Material/Methods Eighteen human cadaveric spines (C2–T1) were evaluated in different testing conditions: intact, with 3 kinds of 4-level hybrid constructs (hybrid C3–4 ACDR+C4–6 ACDF+C6–7ACDR; hybrid C3–5ACDF+C5–6ACDR+C6–7ACDR; hybrid C3–4ACDR+C4–5ACDR+C5–7ACDF); and 4-level fusion. Results Four-level fusion resulted in significant decrease in the C3–C7 ROM compared with the intact spine. The 3 different 4-level hybrid treatment groups caused only slight change at the instrumented levels compared to intact except for flexion. At the adjacent levels, 4-level fusion resulted in significant increase of contribution of both upper and lower adjacent levels. However, for the 3 hybrid constructs, significant changes of motion increase far lower than 4P at adjacent levels were only noted in partial loading conditions. No destabilizing effect or hypermobility were observed in any 4-level hybrid construct. Conclusions Four-level fusion significantly eliminated motion within the construct and increased motion at the adjacent segments. For all 3 different 4-level hybrid constructs, ACDR normalized motion of the index segment and adjacent segments with no significant hypermobility. Compared with the 4-level ACDF condition, the artificial discs in 4-level hybrid constructs had biomechanical advantages compared to fusion in normalizing adjacent level motion. PMID:26694835

  13. Wear characteristics of an unconstrained lumbar total disc replacement under a range of in vitro test conditions

    PubMed Central

    Fisher, John; Hall, Richard M.

    2015-01-01

    Abstract The effect of kinematics, loading and centre of rotation on the wear of an unconstrained total disc replacement have been investigated using the ISO 18192‐1 standard test as a baseline. Mean volumetric wear rate and surface morphological effects were reported. Changing the phasing of the flexions to create a low (but finite) amount of crossing path motion at the bearing surfaces resulted in a significant fall in wear volume. However, the rate of wear was still much larger than previously reported values under zero cross shear conditions. Reducing the load did not result in a significant change in wear rate. Moving the centre of rotation of the disc inferiorly did significantly increase wear rate. A phenomenon of debris re‐attachment on the UHMWPE surface was observed and hypothesised to be due to a relatively harsh tribological operating regime in which lubricant replenishment and particle migration out of the bearing contact zone were limited. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 46–52, 2017. PMID:26411540

  14. Results from a randomized controlled study between total disc replacement and fusion compared with results from a spine register

    PubMed Central

    Berg, Svante; Tropp, Hans

    2010-01-01

    Background Difficulties in performing randomized controlled trials (RCTs) to evaluate new treatment options are increasing. Higher costs and patient unwillingness are the main obstacles. A spinal surgery register has been in use in Sweden for 11 years. Our aim was to determine whether this register can provide the same information as an RCT and whether register data compare favorably with RCT data, making RCTs unnecessary. If not the case, was patient selection or follow-up frequency the cause of any differences? Materials and methods We compared baseline data and outcome, retrieved from our register, between 2 surgical groups, total disc replacement (TDR) and fusion at 1 or 2 levels, performed for degenerative disc disease. One hundred fifty-two patients were part of an RCT, whereas four hundred fifty-five patients had been treated according to an active decision. These 2 subgroups were the subjects for comparison. Results The 2 subgroups were not similar at baseline. Patients who were fused in the non-RCT subgroup were older, had a higher Oswestry Disability Index, and were more frequently smokers than the other patients. The outcome for the non-RCT group showed larger differences in favor of TDR than the RCT did. The nonresponders in the non-RCT group showed worse life quality and disability at baseline, and patients who answered the 1-year follow-up questionnaire but not the 2-year follow-up questionnaire had an inferior clinical result compared with the other patients at 1 year. Conclusion Data from our register showed results similar to the RCT, but a register cannot fully replace an RCT study when evaluating a new treatment option if the RCT has narrower selection than just the diagnosis. In this RCT comparing TDR with posterior fusion, the normal exclusion criteria for TDR were used. These were not registered, so the register could not prevent a possible selection bias, which might also be caused by the nonresponders. PMID:25802653

  15. An uncommon case of Mycoplasma hominis infection after total disc replacement.

    PubMed

    Flouzat-Lachaniette, Charles-Henri; Guidon, Julie; Allain, Jérôme; Poignard, Alexandre

    2013-05-01

    Beside mechanical complications, the majority of adverse events after total disc arthroplasty (TDA) are related to the surgical approach. Septic complications are very uncommon and only one previous case has been published. The objective of this article is to describe the clinical circumstances, treatment, and outcomes of septic complication after TDA at L4-L5, involving an uncommon pathogen (Mycoplasma hominis). A 38-year-old woman underwent a MobiDisc(®) TDA at L4-L5 level for discogenic pain. One month postoperatively, she complained of acute low back and abdominal pain associated with fever (39 °C). C-reactive protein level was elevated (197 mg/L; normal <5 mg/L) and the white blood cell count was normal (7 × 10(9)/L; normal 4-10 × 10(9)/L). A computerized tomography (CT) showed a left psoas-based retroperitoneal abscess. Treatment consisted of open debridement, drainage and empirical antibiotic therapy. Intraoperative cultures yielded M. hominis after 7 days incubation. Antibiotic therapy was adapted and discontinued after 2 months. The patient had failed to mention earlier that she had been suffering from abnormal vaginal discharge for some time and was using an intrauterine contraceptive device. At 1.5-year follow-up, review confirmed healing of the infection with biological normalization without residual collection, radiolucent lines or osteolysis around the prosthesis at radiographs, CT and MRI. Mycoplasma hominis can be involved as an extragenital pathogen in musculoskeletal infections. Because its culture and identification are difficult, special media and real-time PCR are required in case of postoperative deep wound infection after anterior lumbar spine surgery, especially in the case of previous genitourinary infections, to decrease the delay in diagnosis and treatment.

  16. Cervical total disc replacement with the Mobi-C cervical artificial disc compared with anterior discectomy and fusion for treatment of 2-level symptomatic degenerative disc disease: a prospective, randomized, controlled multicenter clinical trial: clinical article.

    PubMed

    Davis, Reginald J; Kim, Kee D; Hisey, Michael S; Hoffman, Gregory A; Bae, Hyun W; Gaede, Steven E; Rashbaum, Ralph F; Nunley, Pierce Dalton; Peterson, Daniel L; Stokes, John K

    2013-11-01

    Cervical total disc replacement (TDR) is intended to treat neurological symptoms and neck pain associated with degeneration of intervertebral discs in the cervical spine. Anterior cervical discectomy and fusion (ACDF) has been the standard treatment for these indications since the procedure was first developed in the 1950s. While TDR has been shown to be a safe and effective alternative to ACDF for treatment of patients with degenerative disc disease (DDD) at a single level of the cervical spine, few studies have focused on the safety and efficacy of TDR for treatment of 2 levels of the cervical spine. The primary objective of this study was to rigorously compare the Mobi-C cervical artificial disc to ACDF for treatment of cervical DDD at 2 contiguous levels of the cervical spine. This study was a prospective, randomized, US FDA investigational device exemption pivotal trial of the Mobi-C cervical artificial disc conducted at 24 centers in the US. The primary clinical outcome was a composite measure of study success at 24 months. The comparative control treatment was ACDF using allograft bone and an anterior plate. A total of 330 patients were enrolled, randomized, and received study surgery. All patients were diagnosed with intractable symptomatic cervical DDD at 2 contiguous levels of the cervical spine between C-3 and C-7. Patients were randomized in a 2:1 ratio (TDR patients to ACDF patients). A total of 225 patients received the Mobi-C TDR device and 105 patients received ACDF. At 24 months only 3.0% of patients were lost to follow-up. On average, patients in both groups showed significant improvements in Neck Disability Index (NDI) score, visual analog scale (VAS) neck pain score, and VAS arm pain score from preoperative baseline to each time point. However, the TDR patients experienced significantly greater improvement than ACDF patients in NDI score at all time points and significantly greater improvement in VAS neck pain score at 6 weeks, and at 3, 6, and

  17. In-situ photopolymerized and monitored implants: successful application to an intervertebral disc replacement

    NASA Astrophysics Data System (ADS)

    Schmocker, Andreas M.; Khoushabi, Azadeh; Bourban, Pierre-Etienne; Schizas, Constantin; Pioletti, Dominique; Moser, Christophe

    2016-02-01

    Photopolymerization is a common method to harden materials initially in a liquid state. A surgeon can directly trigger the solidification of a dental implant or a bone or tissue filler by using ultra-violet light. Traditionally, photopolymerization has been used mainly in dentistry. Over the last decade advances in material development including a wide range of biocompatible gel- and cement-systems open up a new avenue for in-situ photopolymerization. We designed a miniaturized light probe where a photoactive material can be 1) mixed, pressurized and injected 2) photopolymerized or photoactivated and 3) monitored during the chemical reaction. The device enables surgeries to be conducted through a hole smaller than 500 μm in diameter. Using a combination of Raman and fluorescence spectroscopy, the current state of the photopolymerization was inferred and monitored in real time within an in-vitro tissue model. It was also possible to determine roughly the position of the probe within the tissue cavity by analysing the fluorescence signal. Using the technique hydrogels were successfully implanted into a bovine intervertebral disc model. Mechanical tests could not obstruct the functionality of the implant. Finally, the device was also used for other application such as the implantation of a hydrogel into an aneurysm tissue cavity which will be presented at the conference.

  18. Periprosthetic UHMWPE Wear Debris Induces Inflammation, Vascularization, and Innervation After Total Disc Replacement in the Lumbar Spine.

    PubMed

    Veruva, Sai Y; Lanman, Todd H; Isaza, Jorge E; Freeman, Theresa A; Kurtz, Steven M; Steinbeck, Marla J

    2017-05-01

    The pathophysiology and mechanisms driving the generation of unintended pain after total disc replacement (TDR) remain unexplored. Ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris from TDRs is known to induce inflammation, which may result in pain. The purpose of this study was to determine whether (1) periprosthetic UHMWPE wear debris induces immune responses that lead to the production of tumor necrosis factor-α (TNFα) and interleukin (IL)-1ß, the vascularization factors, vascular endothelial growth factor (VEGF) and platelet-derived growth factor-bb (PDGFbb), and the innervation/pain factors, nerve growth factor (NGF) and substance P; (2) the number of macrophages is associated with the production of the aforementioned factors; (3) the wear debris-induced inflammatory pathogenesis involves an increase in vascularization and associated innervation. Periprosthetic tissues from our collection of 11 patients with contemporary TDRs were evaluated using polarized light microscopy to quantify UHMWPE wear particles. The major reason for revision (mean implantation time of 3 years [range, 1-6 years]) was pain. For control subjects, biopsy samples from four patients with degenerative disc disease with severe pain and autopsy samples from three normal patients with no history of back pain were also investigated. Immunohistochemistry and histology were used to identify secretory factors, macrophages, and blood vessels. Immunostained serial sections were imaged at ×200 magnification and using MATLAB and NIH ImageJ, a threshold was determined for each factor and used to quantify positive staining normalized to tissue sectional area. The Mann-Whitney U test was used to compare results from different patient groups, whereas the Spearman Rho test was used to determine correlations. Significance was based on p < 0.05. The mean percent area of all six inflammatory, vascularization, and innervation factors was higher in TDR tissues when compared with normal disc

  19. Dynamic biomechanical examination of the lumbar spine with implanted total disc replacement using a pendulum testing system.

    PubMed

    Daniels, Alan H; Paller, David J; Koruprolu, Sarath; McDonnell, Matthew; Palumbo, Mark A; Crisco, Joseph J

    2012-11-01

    Biomechanical cadaver investigation. To examine dynamic bending stiffness and energy absorption of the lumbar spine with and without implanted total disc replacement (TDR) under simulated physiological motion. The pendulum testing system is capable of applying physiological compressive loads without constraining motion of functional spinal units (FSUs). The number of cycles to equilibrium observed under pendulum testing is a measure of the energy absorbed by the FSU. Five unembalmed, frozen human lumbar FSUs were tested on the pendulum system with axial compressive loads of 181 N, 282 N, 385 N, and 488 N before and after Synthes ProDisc-L TDR implantation. Testing in flexion, extension, and lateral bending began by rotating the pendulum to 5º resulting in unconstrained oscillatory motion. The number of rotations to equilibrium was recorded and bending stiffness (N·m/º) was calculated and compared for each testing mode. In flexion/extension, the TDR constructs reached equilibrium with significantly (P < 0.05) fewer cycles than the intact FSU with compressive loads of 282 N, 385 N, and 488 N. Mean dynamic bending stiffness in flexion, extension, and lateral bending increased significantly with increasing load for both the intact FSU and TDR constructs (P < 0.001). In flexion, with increasing compressive loading from 181 N to 488 N, the bending stiffness of the intact FSUs increased from 4.0 N·m/º to 5.5 N·m/º, compared with 2.1 N·m/º to 3.6 N·m/º after TDR implantation. At each compressive load, the intact FSU was significantly stiffer than the TDR (P < 0.05). Lumbar FSUs with implanted TDR were found to be less stiff, but absorbed more energy during cyclic loading with an unconstrained pendulum system. Although the effects on clinical performance of motion-preserving devices are not fully known, these results provide further insight into the biomechanical behavior of these devices under approximated physiological loading conditions.

  20. Changes in cervical range of motion and sagittal alignment in early and late phases after total disc replacement: radiographic follow-up exceeding 2 years.

    PubMed

    Ahn, Poong-Gi; Kim, Keung Nyun; Moon, Sung Whan; Kim, Keun Su

    2009-12-01

    This was a retrospective clinical study in which the follow-up period exceeded 2 years. The authors investigated the time course of radiographic changes in the cervical range of motion (ROM) and sagittal alignment after cervical total disc replacement involving the ProDisc-C artificial disc. Eighteen patients who underwent C5-6 total disc replacement were followed for an average of 27 months. Cervical neutral and flexion-extension lateral radiographs were obtained before and at 1 and 3 months after surgery for early-phase observations and at the last follow-up for late-phase observation. Segmental ROM values in the treated, superior, and inferior adjacent segments were measured. For whole-neck motion, C2-7 ROM was also measured. The percentage contributions of ROM at functional and adjacent segments to whole-neck motion were calculated. For evaluating sagittal alignment, C2-7 and C5-6 Cobb angles were measured. All data from ProDisc-C arthroplasty were compared with the results obtained in 22 patients who underwent C5-6 interbody fusion in which a Solis cage was used and who were followed for an average of 25 months. In the ProDisc-C group, C2-7 and C5-6 ROM significantly decreased in the early phase after surgery and returned to preoperative levels in the late phase. Both superior and inferior adjacent segments showed significantly decreased ROM in the acute phase after surgery and returned to the preoperative values in the late phase. In terms of contributions to whole-neck motion, the ROM of the functional and adjacent segments did not change significantly compared with the preoperative ROM. In the cage group, C2-7 ROM was also significantly decreased in the early phase after surgery and returned to preoperative levels at the late phase. Both superior and inferior adjacent segments exhibited significantly increased ROM and percentage contributions to whole-neck motion in the early and late phases. Sagittal alignment of the whole cervical spine became

  1. Quality of systematic reviews: an example of studies comparing artificial disc replacement with fusion in the cervical spine.

    PubMed

    Tashani, Osama A; El-Tumi, Hanan; Aneiba, Khaled

    2015-01-01

    Cervical artificial disc replacement (C-ADR) is now an alternative to anterior cervical discectomy and fusion (ACDF). Many studies have evaluated the efficacy of C-ADR compared with ACDF. This led to a series of systematic reviews and meta-analyses to evaluate the evidence of the superiority of one intervention against the other. The aim of the study presented here was to evaluate the quality of these reviews and meta-analyses. Medline via Ovid, Embase, and Cochrane Library were searched using the keywords: (total disk replacement, prosthesis, implantation, discectomy, and arthroplasty) AND (cervical vertebrae, cervical spine, and spine) AND (systematic reviews, reviews, and meta-analysis). Screening and data extraction were conducted by two reviewers independently. Two reviewers then assessed the quality of the selected reviews and meta-analysis using 11-item AMSTAR score which is a validated measurement tool to assess the methodological quality of systematic reviews. Screening of full reports of 46 relevant abstracts resulted in the selection of 15 systematic reviews and/or meta-analyses as eligible for this study. The two reviewers' inter-rater agreement level was high as indicated by kappa of >0.72. The AMSTAR score of the reviews ranged from 3 to 11. Only one study (a Cochrane review) scored 100% (AMSTAR 11). Five studies scored below (AMSTAR 5) indicating low-quality reviews. The most significant drawbacks of reviews of a score below 5 were not using an extensive search strategy, failure to use the scientific quality of the included studies appropriately in formulating a conclusion, not assessing publication bias, and not reporting the excluded studies. With a significant exception of a Cochrane review, the methodological quality of systematic reviews evaluating the evidence of C-ADR versus ACDF has to be improved.

  2. Synthesis and characterization of injectable bioadhesive hydrogels for nucleus pulposus replacement and repair of the damaged intervertebral disc.

    PubMed

    Vernengo, J; Fussell, G W; Smith, N G; Lowman, A M

    2010-05-01

    Bioadhesive polymers are natural or synthetic materials that can be used for soft tissue repair. The aim of this investigation was to develop an injectable, bioadhesive hydrogel with the potential to serve as a synthetic replacement for the nucleus pulposus of the intervertebral disc or as an annulus closure material. Branched copolymers of poly(N-isopropylacrylamide) (PNIPAAm) and poly(ethylene glycol) (PEG) were blended with poly(ethylene imine) (PEI). This three component injectable system can form a precipitated gel at physiological temperature due to the phase transition of PNIPAAm. The injection of glutaraldehyde into the gel core will adhere the implant to the surrounding tissues. (1)H NMR results indicated the successful physical incorporation of PEI into the PNIPAAm-PEG network by blending. In addition, the covalent crosslinking between the amine functionalities on the PEI and the aldehyde functionalities on the glutaraldehyde was verified using FTIR difference spectroscopy. Mechanical characterization of these blends showed a significant increase (p < 0.05) in compressive modulus following glutaraldehyde injection. The in vitro bioadhesive force studies with porcine skin showed a significant increase (p < 0.05) in the mean maximum force of detachment for PNIPAAm-PEG/PEI gels when glutaraldehyde was injected into the gel core. The results of this study indicate that the reactivity between amines and aldehyde functionalities can be exploited to impart bioadhesive properties to PNIPAAm-PEG/PEI copolymers.

  3. Dynamic Biomechanical Examination of the Lumbar Spine with Implanted Total Disc Replacement (TDR) Utilizing a Pendulum Testing System

    PubMed Central

    Daniels, Alan H; Paller, David J; Koruprolu, Sarath; McDonnell, Matthew; Palumbo, Mark A; Crisco, Joseph J

    2013-01-01

    Study Design Biomechanical cadaver investigation Objective To examine dynamic bending stiffness and energy absorption of the lumbar spine with and without implanted Total Disc Replacement (TDR) under simulated physiologic motion. Summary of background data The pendulum testing system is capable of applying physiologic compressive loads without constraining motion of functional spinal units (FSUs). The number of cycles to equilibrium observed under pendulum testing is a measure of the energy absorbed by the FSU. Methods Five unembalmed, frozen human lumbar FSUs were tested on the pendulum system with axial compressive loads of 181N, 282N, 385N, and 488N before and after Synthes ProDisc-L TDR implantation. Testing in flexion, extension, and lateral bending began by rotating the pendulum to 5° resulting in unconstrained oscillatory motion. The number of rotations to equilibrium was recorded and bending stiffness (N-m/°) was calculated and compared for each testing mode. Results In flexion/extension, the TDR constructs reached equilibrium with significantly (p<0.05) fewer cycles than the intact FSU with compressive loads of 282N, 385N and 488N. Mean dynamic bending stiffness in flexion, extension, and lateral bending increased significantly with increasing load for both the intact FSU and TDR constructs (p<0.001). In flexion, with increasing compressive loading from 181N to 488N, the bending stiffness of the intact FSUs increased from 4.0N-m/° to 5.5N-m/°, compared to 2.1N-m/° to 3.6N-m/° after TDR implantation. At each compressive load, the intact FSU was significantly more stiff than the TDR (p<0.05). Conclusion Lumbar FSUs with implanted TDR were found to be less stiff, but also absorbed more energy during cyclic loading with an unconstrained pendulum system. Although the effects on clinical performance of motion preserving devices are not fully known, these results provide further insight into the biomechanical behavior of this device under approximated

  4. The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements

    PubMed Central

    Kurtz, Steven M.; Toth, Jeffrey M.; Siskey, Ryan; Ciccarelli, Lauren; MacDonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, André

    2012-01-01

    Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods. PMID:22904606

  5. The Latest Lessons Learned from Retrieval Analyses of Ultra-High Molecular Weight Polyethylene, Metal-on-Metal, and Alternative Bearing Total Disc Replacements.

    PubMed

    Kurtz, Steven M; Toth, Jeffrey M; Siskey, Ryan; Ciccarelli, Lauren; Macdonald, Dan; Isaza, Jorge; Lanman, Todd; Punt, Ilona; Steinbeck, Marla; Goffin, Jan; van Ooij, André

    2012-03-01

    Knowledge regarding the in vivo performance and periposthetic tissue response of cervical and lumbar total disc replacements (TDRs) continues to expand. This review addresses the following four main questions: 1) What are the latest lessons learned from polyethylene in large joints and how are they relevant to current TDRs? 2) What are the latest lessons learned regarding adverse local tissue reactions from metal-on-metal, CoCr bearings in large joints and how are they relevant to current TDRs? 3) What advancements have been made in understanding the in vivo performance of alternative biomaterials, such as stainless steel and polycarbonate urethane, for TDRs in the past five years? 4) How has retrieval analysis of all these various artificial disc bearing technologies advanced the state of the art in preclinical testing of TDRs? The study of explanted artificial discs and their associated tissues can help inform bearing selection as well as the design of future generations of disc arthroplasty. Analyzing retrieved artificial discs is also essential for validating preclinical test methods.

  6. Five-year results of the prospective, randomized, multicenter, Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential arthrodesis for the treatment of single-level degenerative disc disease.

    PubMed

    Zigler, Jack E; Delamarter, Rick B

    2012-12-01

    The purpose of this study was to evaluate the long-term safety and effectiveness of the ProDisc-L total disc replacement (TDR) as part of an FDA-mandated postmarket approval study. This report summarizes the clinical findings after 5 years of follow-up. Two hundred thirty-six patients were treated and followed up for 5 years; 161 TDRs and 75 fusions had been performed in these patients. The primary outcome was a 10-component success end point. Secondary outcome measures included neurological status, secondary surgery, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36), visual analog scale (VAS) assessing pain and satisfaction, radiographic data, narcotic use, activity, and recreation status. Patients were monitored through their 5-year postoperative visits under the FDA postmarket surveillance provisions in the original investigational device exemption approval. The overall follow-up rate at 5 years was 81.8%. Study success demonstrated that TDR was noninferior to fusion with a 12.5% margin (p = 0.0099). Both TDR and fusion treatment groups maintained significant improvement on the ODI at 5 years compared with baseline (p < 0.0001). Secondary surgeries at the index level were performed in 12% of fusion patients and 8% of TDR patients. Radiographically, none of the TDRs developed spontaneous fusion. The segmental range of motion following TDR remained within normal range, although it decreased by approximately 0.5° in years 3 to 5. The VAS pain scores decreased from preoperative values by 48% in both treatment groups at 5 years. Patient satisfaction remained high in both groups (77%), while the percentage of patients indicating that they would have the surgery again was higher in TDR patients (82.5%) than in fusion patients (68.0%). Patients in both groups maintained significant improvement during the 5-year follow-up. The TDR group had significantly better improvement on some scales. Although TDR patients avoid the stiffness of fusion and

  7. A case of cervical metastases in a patient with preexisting cervical disc replacement and fusion after 2-year symptom-free interval: when do we need interdisciplinary diagnostics?

    PubMed

    Melloh, Markus; Barz, Thomas

    2012-08-01

    Recurrent cervical symptoms frequently occur after cervical disc replacement and fusion. To date, no algorithm for the diagnostic assessment of these symptoms has been established. We present a case report and review of the literature to illustrate the need for interdisciplinary diagnostics in recurrent cervicobrachialgia without pathological cervical imaging. The hospital chart, medical history, physical examination, and imaging of a single patient were reviewed. A 53-year-old man with preexisting cervical disc replacement and fusion presented with a new episode of cervicobrachialgia after a 2-year symptom-free interval. Cervical magnetic resonance imaging (MRI) showed no pathological findings. Six months later the patient reported increasing symptoms including numbness and weakness of the right arm. Repeated cervical MRI and thoracic computed tomography revealed cervical metastases with intraspinal tumor growth and an underlying extensive small cell bronchial carcinoma. In recurrent cervicobrachialgia, without pathological cervical imaging, interdisciplinary diagnostics are needed. Basic diagnostic tests may assist to exclude severe non-vertebrogenic pathologies.

  8. Long term preservation of motion with artificial cervical disc implants: A comparison between cervical disc replacement and rigid fusion with cage

    PubMed Central

    Cincu, Rafael; Lorente, Francisco de Asis; Gomez, Joaquin; Eiras, Jose; Agrawal, Amit

    2014-01-01

    Background: With the advancement of technologies there is more interest in the maintenance of the spine's biomechanical properties focusing on the preservation of the functional motion segment. In present article we describe our experience with 25 cases managed with artificial cervical discs with 28 Solis cage following cervical discectomy with a mean follow-up period of 7.5 year. Materials and Methods: All surgeries were performed by single surgeon from March 2004 to June 2005 with a follow-up till date. Patients with symptomatic single or multiple level diseases that had no prior cervical surgery were candidates for the study. Cohort demographics were comparable. Standardized clinical outcome measures and radiographic examinations were used at prescribed post-operative intervals to compare the treatment groups. Relief in radicular pain, cervical spine motion, and degenerative changes at follow-up were noted. Results: In a total 53 cases, the mean age in prosthesis group was 47 years (age range: 30-63 years) and mean age in cage group was 44 years (32-62 years). Mean hospital stay was 2.7 days in both the groups. At 4 weeks complete cervical movements could be achieved in 19 cases in artificial disc group. Maintenance of movement after 7.5 years was in 76% of these patients. Lordosis was maintained in all cases till date. There was no mortality or wound infection in our series. Conclusions: We conclude that artificial cervical disc could be an alternative to fixed spinal fusion as it represents the most physiological substitute of disc. However, there is need for further studies to support the use of artificial cervical disc prosthesis. PMID:25685218

  9. Cervical total disc replacement exhibits similar stiffness to intact cervical functional spinal units tested on a dynamic pendulum testing system.

    PubMed

    Esmende, Sean M; Daniels, Alan H; Paller, David J; Koruprolu, Sarath; Palumbo, Mark A; Crisco, Joseph J

    2015-01-01

    The pendulum testing system is capable of applying physiologic compressive loads without constraining the motion of functional spinal units (FSUs). The number of cycles to equilibrium observed under pendulum testing is a measure of the energy absorbed by the FSU. To examine the dynamic bending stiffness and energy absorption of the cervical spine, with and without implanted cervical total disc replacement (TDR) under simulated physiologic motion. A biomechanical cadaver investigation. Nine unembalmed, frozen human cervical FSUs from levels C3-C4 and C5-C6 were tested on the pendulum system with axial compressive loads of 25, 50, and 100 N before and after TDR implantation. Testing in flexion, extension, and lateral bending began by rotating the pendulum to 5°, resulting in unconstrained oscillatory motion. The number of rotations to equilibrium was recorded and the bending stiffness (Newton-meter/°) was calculated and compared for each testing mode. In flexion/extension, with increasing compressive loading from 25 to 100 N, the average number of cycles to equilibrium for the intact FSUs increased from 6.6 to 19.1, compared with 4.1 to 12.7 after TDR implantation (p<.05 for loads of 50 and 100 N). In flexion, with increasing compressive loading from 25 to 100 N, the bending stiffness of the intact FSUs increased from 0.27 to 0.59 Nm/°, compared with 0.21 to 0.57 Nm/° after TDR implantation. No significant differences were found in stiffness between the intact FSU and the TDR in flexion/extension and lateral bending at any load (p<.05). Cervical FSUs with implanted TDR were found to have similar stiffness, but had greater energy absorption than intact FSUs during cyclic loading with an unconstrained pendulum system. These results provide further insight into the biomechanical behavior of cervical TDR under approximated physiologic loading conditions. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Cervical artificial disc replacement versus fusion in the cervical spine: a systematic review comparing multilevel versus single-level surgery

    PubMed Central

    Kepler, Christopher K.; Brodt, Erika D.; Dettori, Joseph R.; Albert, Todd J.

    2012-01-01

    Study design: Systematic review. Clinical questions: What is the effectiveness of multilevel cervical artificial disc replacement (C-ADR) compared with multilevel fusion with respect to pain and functional outcomes, and are the two procedures comparable in terms of safety? What is the effectiveness of multilevel C-ADR compared with single-level C-ADR with respect to pain and functional outcomes, and are the two procedures comparable in terms of safety? Methods: A systematic review was undertaken for articles published up to October 2011. Electronic databases and reference lists of key articles were searched to identify studies comparing multilevel C-ADR with multilevel anterior cervical discectomy and fusion (ACDF) or comparing multilevel C-ADR with single-level C-ADR. Studies which compared these procedures in the lumbar or thoracic spine or that reported alignment outcomes only were excluded. Two independent reviewers assessed the strength of evidence using the GRADE criteria and disagreements were resolved by consensus. Results: Two studies compared multilevel C-ADR with multilevel ACDF. While both reported improved Neck Disability Index (NDI) and Short-Form 36 (SF-36) scores after C-ADR compared with ACDF, only one study reported statistically significant results. Seven studies compared single-level C-ADR with multilevel C-ADR. Results were similar in terms of overall success, NDI and SF-36 scores, and patient satisfaction. There is discrepant information regarding rates of heterotopic ossification; dysphagia rate may be higher in multilevel C-ADR. Conclusions: The literature suggests that outcomes are at least similar for multilevel C-ADR and ACDF and may favor C-ADR. Future studies are necessary before firm recommendations can be made favoring one treatment strategy. Multilevel C-ADR seems to have similar results to single-level C-ADR but may have higher rates of heterotopic ossification and dysphagia. PMID:23236310

  11. Cervical artificial disc replacement versus fusion in the cervical spine: a systematic review comparing multilevel versus single-level surgery.

    PubMed

    Kepler, Christopher K; Brodt, Erika D; Dettori, Joseph R; Albert, Todd J

    2012-02-01

     Systematic review.Clinical questions: What is the effectiveness of multilevel cervical artificial disc replacement (C-ADR) compared with multilevel fusion with respect to pain and functional outcomes, and are the two procedures comparable in terms of safety? What is the effectiveness of multilevel C-ADR compared with single-level C-ADR with respect to pain and functional outcomes, and are the two procedures comparable in terms of safety?  A systematic review was undertaken for articles published up to October 2011. Electronic databases and reference lists of key articles were searched to identify studies comparing multilevel C-ADR with multilevel anterior cervical discectomy and fusion (ACDF) or comparing multilevel C-ADR with single-level C-ADR. Studies which compared these procedures in the lumbar or thoracic spine or that reported alignment outcomes only were excluded. Two independent reviewers assessed the strength of evidence using the GRADE criteria and disagreements were resolved by consensus.  Two studies compared multilevel C-ADR with multilevel ACDF. While both reported improved Neck Disability Index (NDI) and Short-Form 36 (SF-36) scores after C-ADR compared with ACDF, only one study reported statistically significant results. Seven studies compared single-level C-ADR with multilevel C-ADR. RESULTS were similar in terms of overall success, NDI and SF-36 scores, and patient satisfaction. There is discrepant information regarding rates of heterotopic ossification; dysphagia rate may be higher in multilevel C-ADR.  The literature suggests that outcomes are at least similar for multilevel C-ADR and ACDF and may favor C-ADR. Future studies are necessary before firm recommendations can be made favoring one treatment strategy. Multilevel C-ADR seems to have similar results to single-level C-ADR but may have higher rates of heterotopic ossification and dysphagia.

  12. The Mobi-C cervical disc for one-level and two-level cervical disc replacement: a review of the literature

    PubMed Central

    Alvin, Matthew D; Mroz, Thomas E

    2014-01-01

    Background Cervical disc arthroplasty (CDA) is a novel motion-preserving procedure that is an alternative to fusion. The Mobi-C disc prosthesis, one of many Food and Drug Administration (FDA)-approved devices for CDA, is the only FDA-approved prosthesis for two-level CDA. Hence, it may allow for improved outcomes compared with multilevel fusion procedures. Purpose To critically assess the available literature on CDA with the Mobi-C prosthesis, with a focus on two-level CDA. Methods All clinical articles involving the Mobi-C disc prosthesis for CDA through September 1, 2014 were identified on Medline. Any paper that presented Mobi-C CDA clinical results was included. Study design, sample size, length of follow-up, use of statistical analysis, quality of life outcome scores, conflict of interest, and complications were recorded. Results Fifteen studies were included that investigated Mobi-C CDA, only one of which was a level Ib randomized control trial. All studies included showed non-inferiority of one-level Mobi-C CDA to one-level anterior cervical discectomy and fusion (ACDF). Only one study analyzed outcomes of one-level versus two-level Mobi-C CDA, and only one study analyzed two-level Mobi-C CDA versus two-level ACDF. In comparison with other cervical disc prostheses, the Mobi-C prosthesis is associated with higher rates of heterotopic ossification (HO). Studies with conflicts of interest reported lower rates of HO. Adjacent segment degeneration or disease, along with other complications, were not assessed in most studies. Conclusion One-level Mobi-C CDA is non-inferior, but not superior, to one-level ACDF for patients with cervical degenerative disc disease. The Mobi-C CDA procedure is associated with high rates of HO. Two-level Mobi-C CDA may be superior to two-level ACDF. However, insufficient evidence exists, thereby mandating a need for unbiased, well-designed prospective studies with well-defined outcomes in the future. PMID:25473319

  13. Is Two-Level Cervical Disc Replacement More Cost-Effective than Anterior Cervical Discectomy and Fusion at 7 Years?

    PubMed

    Merrill, Robert K; McAnany, Steven J; Albert, Todd J; Qureshi, Sheeraz A

    2017-08-14

    Cost-effectiveness analysis. Investigate the 7-year cost-effectiveness of two-level cervical disc replacement (CDR) and anterior cervical discectomy and fusion (ACDF). CDR and ACDF are both effective treatment strategies for managing degenerative conditions of the cervical spine. CDR has been shown to be a more-cost effective intervention in the short term, but the long-term cost-effectiveness has not been established. We analyzed 7-year follow-up data from the two-level Medtronic Prestige LP investigational device exemption study. Short-form 36 (SF-36) data were converted into health utility scores using the SF-6D algorithm. Costs were based on direct costs from the payer perspective, and effectiveness was measured as quality adjusted life years (QALYs). The willingness to pay (WTP) threshold was set to $50,000/QALY. A probabilistic sensitivity analysis was conducted via Monte Carlo simulation. Two-level CDR had a 7-year cost of $176,654.19, generated 4.65 QALYs, and had a cost-effectiveness ratio of $37,993.53/QALY. Two-level ACDF had a 7-year cost of $158,373.48, generated 4.44 QALYs, and had a cost-effectiveness ratio of $35,635.72. CDR was associated with an incremental cost of $18,280.71 and an incremental effectiveness of 0.21 QALYs, resulting in an incremental cost-effectiveness ratio (ICER) of $89,021.04, above the WTP threshold. Our Monte Carlo simulation demonstrated CDR would be chosen 46% of the time based on 10,000 simulations. Two-level CDR and ACDF are both cost-effective procedures at 7-year follow-up for treating degenerative conditions of the cervical spine. Based on an ICER of $89,021.04/QALY, we cannot conclude which treatment is the more cost-effective option at 7-years. CDR would be chosen 46% of the time based on 10,000 iterations of our Monte Carlo probabilistic sensitivity analysis. 3.

  14. Total disc replacement compared to lumbar fusion: a randomised controlled trial with 2-year follow-up

    PubMed Central

    Tullberg, Tycho; Branth, Björn; Olerud, Claes; Tropp, Hans

    2009-01-01

    The study design includes a prospective, randomised controlled study comparing total disc replacement (TDR) with posterior fusion. The main objective of this study is to compare TDR with lumbar spinal fusion, in terms of clinical outcome, in patients referred to a spine clinic for surgical evaluation. Fusion is effective for treating chronic low back pain (LBP), but has drawbacks, such as stiffness and possibly adjacent level degradation. Motion-preserving options have emerged, of which TDR is frequently used because of these drawbacks. How the results of TDR compare to fusion, however, is uncertain. One hundred and fifty-two patients with a mean age of 40 years (21–55) were included: 90 were women, and 80 underwent TDR. The patients had not responded to a conservative treatment programme and suffered from predominantly LBP, with varying degrees of leg pain. Diagnosis was based on clinical examination, radiographs, MRI, and in unclear cases, diagnostic injections. Outcome measures were global assessment (GA), VAS for back and leg pain, Oswestry Disability Index, SF36 and EQ5D at 1 and 2 years. Follow-up rate was 100%, at both 1 and 2 years. All outcome variables improved in both groups between preoperative and follow-up assessment. The primary outcome measure, GA, revealed that 30% in the TDR group and 15% in the fusion group were totally pain-free at 2 years (P = 0.031). TDR patients had reached maximum recovery in virtually all variables at 1 year, with significant differences compared to the fusion group. The fusion patients continued to improve and at 2 years had results similar to TDR patients apart from numbers of pain-free. Complications and reoperations were similar in both groups, but pedicle screw removal as additive surgery, was frequent in the fusion group. One year after surgery, TDR was superior to spinal fusion in clinical outcome, but this difference had diminished by 2 years, apart from (VAS for back pain and) numbers of pain-free. The

  15. Benchmarking in the SWISSspine Registry: results of 52 Dynardi lumbar total disc replacements compared with the data pool of 431 other lumbar disc prostheses

    PubMed Central

    Aghayev, Emin; Röder, Christoph; Etter, Christian; Schwarzenbach, Othmar

    2010-01-01

    The SWISSspine registry is the first mandatory registry of its kind in the history of Swiss orthopaedics and it follows the principle of “coverage with evidence development”. Its goal is the generation of evidence for a decision by the Swiss federal office of health about reimbursement of the concerned technologies and treatments by the basic health insurance of Switzerland. Recently, developed and clinically implemented, the Dynardi total disc arthroplasty (TDA) accounted for 10% of the implanted lumbar TDAs in the registry. We compared the outcomes of patients treated with Dynardi to those of the recipients of the other TDAs in the registry. Between March 2005 and October 2009, 483 patients with single-level TDA were documented in the registry. The 52 patients with a single Dynardi lumbar disc prosthesis implanted by two surgeons (CE and OS) were compared to the 431 patients who received one of the other prostheses. Data were collected in a prospective, observational multicenter mode. Surgery, implant, 3-month, 1-year, and 2-year follow-up forms as well as comorbidity, NASS and EQ-5D questionnaires were collected. For statistical analyses, the Wilcoxon signed-rank test and chi-square test were used. Multivariate regression analyses were also performed. Significant and clinically relevant reduction of low back pain and leg pain as well as improvement in quality of life was seen in both groups (P < 0.001 postop vs. preop). There were no inter-group differences regarding postoperative pain levels, intraoperative and follow-up complications or revision procedures with a new hospitalization. However, significantly more Dynardi patients achieved a minimum clinically relevant low back pain alleviation of 18 VAS points and a quality of life improvement of 0.25 EQ-5D points. The patients with Dynardi prosthesis showed a similar outcome to patients receiving the other TDAs in terms of postoperative low back and leg pain, complications, and revision procedures. A

  16. A case of cervical metastases in a patient with preexisting cervical disc replacement and fusion after 2-year symptom-free interval: when do we need interdisciplinary diagnostics?

    PubMed Central

    Melloh, Markus; Barz, Thomas

    2012-01-01

    Recurrent cervical symptoms frequently occur after cervical disc replacement and fusion. To date, no algorithm for the diagnostic assessment of these symptoms has been established. We present a case report and review of the literature to illustrate the need for interdisciplinary diagnostics in recurrent cervicobrachialgia without pathological cervical imaging. The hospital chart, medical history, physical examination, and imaging of a single patient were reviewed. A 53-year-old man with preexisting cervical disc replacement and fusion presented with a new episode of cervicobrachialgia after a 2-year symptom-free interval. Cervical magnetic resonance imaging (MRI) showed no pathological findings. Six months later the patient reported increasing symptoms including numbness and weakness of the right arm. Repeated cervical MRI and thoracic computed tomography revealed cervical metastases with intraspinal tumor growth and an underlying extensive small cell bronchial carcinoma. In recurrent cervicobrachialgia, without pathological cervical imaging, interdisciplinary diagnostics are needed. Basic diagnostic tests may assist to exclude severe non-vertebrogenic pathologies. PMID:23526906

  17. Adjacent Segment Disease in a Patient With Klippel-Feil Syndrome and Radiculopathy: Surgical Treatment With Two-Level Disc Replacement

    PubMed Central

    Reyes-Sánchez, Alejandro; Rosales-Olivares, Luis Miguel

    2007-01-01

    Klippel-Feil syndrome (KFS) is a complex congenital condition characterized by improper segmentation of cervical motion segments that could contribute to undesirable adjacent segment degeneration. KFS patients have a strong tendency to present with disease in the adjacent segments. When this condition is present, anterior decompression followed by total disc replacement can be performed safely and can lead to good clinical results. This treatment has theoretical advantages compared with anterior decompression and fusion. Comparative studies and long-term follow-up are needed. Complications associated with fusion include loss of a motion segment, disc height loss, subsidence of the graft, progressive degenerative changes at the adjacent level, graft-related complications, and graft-site complications. Such new technologies as motion preservation spine arthroplasty represent attempts to avoid these complications. Here we present a case report of a 62-year-old female patient with type I congenital fusion at the C5–6 level, with a history of neck pain and right radiculopathy at C5–7. X-rays and MRI show evidence of adjacent segment degeneration at levels above and below congenital fusion. The patient's preoperative visual analog score (VAS) for neck pain was 7 out of a possible 10, her score for right upper extremity pain was 8 out of 10, and her Neck Disability Index (NDI) was 32%. Surgical treatment consisted of anterior decompression and total disc replacement at both levels. At 1-year follow-up, the patient's VAS for neck pain was 2 out of 10, her VAS score for right upper extremity pain was 1 of 10, and her NDI was 9%. PMID:25802590

  18. Adjacent segment disease in a patient with klippel-feil syndrome and radiculopathy: surgical treatment with two-level disc replacement.

    PubMed

    Reyes-Sánchez, Alejandro; Zárate-Kalfópulos, Barón; Rosales-Olivares, Luis Miguel

    2007-01-01

    Klippel-Feil syndrome (KFS) is a complex congenital condition characterized by improper segmentation of cervical motion segments that could contribute to undesirable adjacent segment degeneration. KFS patients have a strong tendency to present with disease in the adjacent segments. When this condition is present, anterior decompression followed by total disc replacement can be performed safely and can lead to good clinical results. This treatment has theoretical advantages compared with anterior decompression and fusion. Comparative studies and long-term follow-up are needed. Complications associated with fusion include loss of a motion segment, disc height loss, subsidence of the graft, progressive degenerative changes at the adjacent level, graft-related complications, and graft-site complications. Such new technologies as motion preservation spine arthroplasty represent attempts to avoid these complications. Here we present a case report of a 62-year-old female patient with type I congenital fusion at the C5-6 level, with a history of neck pain and right radiculopathy at C5-7. X-rays and MRI show evidence of adjacent segment degeneration at levels above and below congenital fusion. The patient's preoperative visual analog score (VAS) for neck pain was 7 out of a possible 10, her score for right upper extremity pain was 8 out of 10, and her Neck Disability Index (NDI) was 32%. Surgical treatment consisted of anterior decompression and total disc replacement at both levels. At 1-year follow-up, the patient's VAS for neck pain was 2 out of 10, her VAS score for right upper extremity pain was 1 of 10, and her NDI was 9%.

  19. Comparison of single-level cervical fusion and a metal-on-metal cervical disc replacement device.

    PubMed

    Riina, Joseph; Patel, Amisha; Dietz, John W; Hoskins, Jeffery S; Trammell, Terry R; Schwartz, David D

    2008-04-01

    Cervical fusion is the common treatment for cervical disc disease but can cause secondary disorders. The Prestige ST cervical disc prosthesis (Medtronic Sofamor Danek, Memphis, TN) was designed to preserve spinal motion to potentially limit the secondary disorders. In this article, we report 2-year results from a single-center study comparing use of this device with use of anterior cervical discectomy and fusion (ACDF). Nineteen patients were prospectively randomized to receive the device or to undergo ACDF. Twenty-four months after surgery, patients who received the device demonstrated improvement in neck pain, arm pain, and neurologic function. In our cohort, patients who underwent arthroplasty demonstrated greater improvement in neurologic function and neck pain than patients who underwent cervical discectomy and fusion.

  20. Utilization trends of cervical artificial disc replacement during the FDA investigational device exemption clinical trials compared to anterior cervical fusion.

    PubMed

    Qureshi, Sheeraz A; Koehler, Steven M; Lu, Young; Cho, Samuel; Hecht, Andrew C

    2013-12-01

    While anterior cervical discectomy and fusion (ACDF) is the gold standard surgical treatment for cervical disc disease, concerns regarding adjacent segment degeneration lead to the development of cervical disc arthroplasty (CDA). This study compares the utilization trends of CDA versus ACDF during the period of the Food and Drug Administration Investigational Device Exemption clinical trials from 2004 to 2007. The Healthcare Cost and Utilization Project Nationwide Inpatient Sample database was used to identify CDA and ACDF procedures performed in the USA between 2004 and 2007. The prevalence of CDA and ACDF procedures was estimated and stratified by age, sex, diagnosis, census region, payor class, and hospital characteristics. The average length of hospital stay, total charges, and costs were also estimated. The number of CDA surgeries significantly increased annually from 2004 to 2007 and mostly took place at urban non-teaching hospitals. There were no regional differences between CDA and ACDF utilization. There was no difference between sex or admission type between CDA and ACDF patients. ACDF patients were older and had more diabetes, hypertension, and chronic obstructive pulmonary disease. CDA patients were more likely to be discharged home and had shorter hospital stays but had a higher rate of deep venous thrombosis than ACDF patients. Significantly more CDA patients had private insurance while more ACDF patients had Medicare. The average cost was higher for ACDF than CDA. While ACDF dominated surgical intervention for cervical disc disease during the trial period, CDA utilization increased at a significantly greater rate suggesting rapid early adoption.

  1. Subsequent surgery rates after cervical total disc replacement using a Mobi-C Cervical Disc Prosthesis versus anterior cervical discectomy and fusion: a prospective randomized clinical trial with 5-year follow-up.

    PubMed

    Jackson, Robert J; Davis, Reginald J; Hoffman, Gregory A; Bae, Hyun W; Hisey, Michael S; Kim, Kee D; Gaede, Steven E; Nunley, Pierce Dalton

    2016-05-01

    OBJECTIVE Cervical total disc replacement (TDR) has been shown in a number of prospective clinical studies to be a viable treatment alternative to anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic degenerative disc disease. In addition to preserving motion, evidence suggests that cervical TDR may result in a lower incidence of subsequent surgical intervention than treatment with fusion. The goal of this study was to evaluate subsequent surgery rates up to 5 years in patients treated with TDR or ACDF at 1 or 2 contiguous levels between C-3 and C-7. METHODS This was a prospective, multicenter, randomized, unblinded clinical trial. Patients with symptomatic degenerative disc disease were enrolled to receive 1- or 2-level treatment with either TDR as the investigational device or ACDF as the control treatment. There were 260 patients in the 1-level study (179 TDR and 81 ACDF patients) and 339 patients in the 2-level study (234 TDR and 105 ACDF patients). RESULTS At 5 years, the occurrence of subsequent surgical intervention was significantly higher among ACDF patients for 1-level (TDR, 4.5% [8/179]; ACDF, 17.3% [14/81]; p = 0.0012) and 2-level (TDR, 7.3% [17/234]; ACDF, 21.0% [22/105], p = 0.0007) treatment. The TDR group demonstrated significantly fewer index- and adjacent-level subsequent surgeries in both the 1- and 2-level cohorts. CONCLUSIONS Five-year results showed treatment with cervical TDR to result in a significantly lower rate of subsequent surgical intervention than treatment with ACDF for both 1 and 2 levels of treatment. Clinical trial registration no.: NCT00389597 ( clinicaltrials.gov ).

  2. Cost-effectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion: clinical article.

    PubMed

    Qureshi, Sheeraz A; McAnany, Steven; Goz, Vadim; Koehler, Steven M; Hecht, Andrew C

    2013-11-01

    In recent years, there has been increased interest in the use of cervical disc replacement (CDR) as an alternative to anterior cervical discectomy and fusion (ACDF). While ACDF is a proven intervention for patients with myelopathy or radiculopathy, it does have inherent limitations. Cervical disc replacement was designed to preserve motion, avoid the limitations of fusion, and theoretically allow for a quicker return to activity. A number of recently published systematic reviews and randomized controlled trials have demonstrated positive clinical results for CDR, but no studies have revealed which of the 2 treatment strategies is more cost-effective. The purpose of this study was to evaluate the cost-effectiveness of CDR and ACDF by using the power of decision analysis. Additionally, the authors aimed to identify the most critical factors affecting procedural cost and effectiveness and to define thresholds for durability and function to focus and guide future research. The authors created a surgical decision model for the treatment of single-level cervical disc disease with associated radiculopathy. The literature was reviewed to identify possible outcomes and their likelihood following CDR and ACDF. Health state utility factors were determined from the literature and assigned to each possible outcome, and procedural effectiveness was expressed in units of quality-adjusted life years (QALYs). Using ICD-9 procedure codes and data from the Nationwide Inpatient Sample, the authors calculated the median cost of hospitalization by multiplying hospital charges by the hospital-specific cost-to-charge ratio. Gross physician costs were determined from the mean Medicare reimbursement for each current procedural terminology (CPT) code. Uncertainty as regards both cost and effectiveness numbers was assessed using sensitivity analysis. In the reference case, the model assumed a 20-year duration for the CDR prosthesis. Cervical disc replacement led to higher average QALYs gained

  3. Differences between 1- and 2-level cervical arthroplasty: more heterotopic ossification in 2-level disc replacement: Clinical article.

    PubMed

    Wu, Jau-Ching; Huang, Wen-Cheng; Tsai, Hsiao-Wen; Ko, Chin-Chu; Fay, Li-Yu; Tu, Tsung-Hsi; Wu, Ching-Lan; Cheng, Henrich

    2012-06-01

    The most currently accepted indication for cervical arthroplasty is 1- or 2-level degenerative disc disease (DDD) refractory to medical treatment. However, the randomized and controlled clinical trials by the US FDA investigational device exemption studies only compared cervical arthroplasty with anterior cervical discectomy and fusion for 1-level disease. Theoretically, 2-level cervical spondylosis usually implicates more advanced degeneration, whereas the 1-level DDD can be caused by merely a soft-disc herniation. This study aimed to investigate the differences between 1- and 2-level cervical arthroplasty. The authors analyzed data obtained in 87 consecutive patients who underwent 1- or 2-level cervical arthroplasty with Bryan disc. The patients were divided into the 1-level and the 2-level treatment groups. Clinical outcomes were measured using the visual analog scale (VAS) for the neck and arm pain and the Neck Disability Index (NDI), with a minimum follow-up of 30 months. Radiographic outcomes were evaluated on both radiographs and CT scans. The study analyzed 98 levels of Bryan cervical arthroplasty in 70 patients (80.5%) who completed the evaluations in a mean follow-up period of 46.21 ± 9.85 months. There were 22 females (31.4%) and 48 males (68.6%), whose mean age was 46.57 ± 10.07 years at the time of surgery. The 1-level group had 42 patients (60.0%), while the 2-level group had 28 patients (40.0%). Patients in the 1-level group were younger than those in the 2-level group (mean 45.00 vs 48.93 years, p = 0.111 [not significant]). Proportional sex compositions and perioperative prescription of nonsteroidal antiinflammatory drugs were also similar in both groups (p = 0.227 and p = 1.000). The 2-level group had significantly greater EBL during surgery than the 1-level group (220.80 vs 111.89 ml, p = 0.024). Heterotopic ossification was identified more frequently in the 2-level group than the 1-level group (75.0% vs 40.5%, p = 0.009). Although most of the

  4. Internal carotid artery dissection after anterior cervical disc replacement: first case report and literature review of vascular complications of the approach.

    PubMed

    Loret, Jean-Edouard; Francois, Patrick; Papagiannaki, Chrysanthi; Cottier, Jean-Philippe; Terrier, Louis-Marie; Zemmoura, Ilyess

    2013-07-01

    We report the case of a 41-year-old woman who underwent cervical total disc replacement at C4C5 and C5C6 levels and fusion at C6C7 level through an anterior right-side approach. After anesthesia recovery, the patient presented left hemiparesia and facial palsy due to large right hemispheric stroke. Diffusion-weighted magnetic resonance imaging was performed as soon as the patient developed neurologic symptoms of stroke and revealed a right internal carotid artery dissection. Digital substraction angiography, endovascular stenting, angioplasty and thrombectomy were performed. Six months after treatment, clinical examination showed mild left-arm spasticity. To the best of our knowledge, only two cases of internal carotid artery stroke without dissection or thrombosis are reported. In conclusion, although vascular complications are rare after anterior cervical spine procedure, internal carotid artery dissection can occur. Suspected risk factors are prolonged retraction of the carotid artery and neck extension.

  5. Prospective, Randomized Comparison of One-level Mobi-C Cervical Total Disc Replacement vs. Anterior Cervical Discectomy and Fusion: Results at 5-year Follow-up

    PubMed Central

    Zigler, Jack E.; Jackson, Robert; Nunley, Pierce D.; Bae, Hyun W.; Kim, Kee D.; Ohnmeiss, Donna D.

    2016-01-01

    Introduction There is increasing interest in the role of cervical total disc replacement (TDR) as an alternative to anterior cervical discectomy and fusion (ACDF). Multiple prospective randomized studies with minimum 2 year follow-up have shown TDR to be at least as safe and effective as ACDF in treating symptomatic degenerative disc disease at a single level. The purpose of this study was to compare outcomes of cervical TDR using the Mobi-C® with ACDF at 5-year follow-up. Methods This prospective, randomized, controlled trial was conducted as a Food and Drug Administration regulated Investigational Device Exemption trial across 23 centers with 245 patients randomized (2:1) to receive TDR with Mobi-C® Cervical Disc Prosthesis or ACDF with anterior plate and allograft. Outcome assessments included a composite overall success score, Neck Disability Index (NDI), visual analog scales (VAS) assessing neck and arm pain, Short Form-12 (SF-12) health survey, patient satisfaction, major complications, subsequent surgery, segmental range of motion, and adjacent segment degeneration. Results The 60-month follow-up rate was 85.5% for the TDR group and 78.9% for the ACDF group. The composite overall success was 61.9% with TDR vs. 52.2% with ACDF, demonstrating statistical non-inferiority. Improvements in NDI, VAS neck and arm pain, and SF-12 scores were similar between groups and were maintained from earlier follow-up through 60 months. There was no significant difference between TDR and ACDF in adverse events or major complications. Range of motion was maintained with TDR through 60 months. Device-related subsequent surgeries (TDR: 3.0%, ACDF: 11.1%, p<0.02) and adjacent segment degeneration at the superior level (TDR: 37.1%, ACDF: 54.7%, p<0.03) were significantly lower for TDR patients. Conclusions Five-year results demonstrate the safety and efficacy of TDR with the Mobi-C as a viable alternative to ACDF with the potential advantage of lower rates of reoperation and

  6. Cervical artificial disc replacement versus fusion in the cervical spine: a systematic review comparing long-term follow-up results from two FDA trials

    PubMed Central

    Mummaneni, Praveen V.; Amin, Beejal Y.; Wu, Jau-Ching; Brodt, Erika D.; Dettori, Joseph R.; Sasso, Rick C.

    2012-01-01

    Study design: Systematic review. Clinical question: Does single-level unconstrained, semiconstrained, or fully constrained cervical artificial disc replacement (C-ADR) improve health outcomes compared with single-level anterior cervical discectomy and fusion (ACDF) in the long-term? Methods: A systematic review was undertaken for articles published up to October 2011. Electronic databases and reference lists of key articles were searched to identify US Food and Drug Administration (FDA) studies reporting long-term (≥ 48 months) follow-up results of C-ADR compared with ACDF. Non-FDA trials and FDA trials reporting outcomes at short-term or mid-term follow-up periods were excluded. Two independent reviewers assessed the strength of evidence using the GRADE criteria and disagreements were resolved by consensus. Results: Two FDA trials reporting outcomes following C-ADR (Bryan disc, Prestige disc) versus ACDF at follow-up periods of 48 months and 60 months were found (follow-up rates are 68.7% [318/463] and 50.1% [271/541], respectively). Patients in the C-ADR group showed a higher rate of overall success, greater improvements in Neck Disability Index, neck and arm pain scores, and SF-36 PhysicalComponent Scores at long-term follow-up compared with those in the ACDF group. The rate of adjacent segment disease was less in the C-ADR group versus the ACDF group at 60 months (2.9% vs 4.9%). Normal segmental motion was maintained in the C-ADR group. Furthermore, rates of revision and supplemental fixation surgical procedures were lower in the arthroplasty group. Conclusions: C-ADR is a viable treatment option for cervical herniated disc/spondylosis with radiculopathy resulting in improved clinical outcomes, maintenance of normal segmental motion, and low rates of subsequent surgical procedures at 4 to 5 years follow-up. More studies with long-term follow-up are warranted. PMID:23236315

  7. Comparative Analysis between Total Disc Replacement and Posterior Foraminotomy for Posterolateral Soft Disc Herniation with Unilateral Radiculopathy : Clinical and Biomechanical Results of a Minimum 5 Years Follow-up

    PubMed Central

    Kim, Kyoung-Tae; Cho, Dae-Chul; Sung, Joo-Kyung; Kim, Young-Baeg; Kim, Du Hwan

    2017-01-01

    Objective To compare the clinical outcomes and biomechanical effects of total disc replacement (TDR) and posterior cervical foraminotomy (PCF) and to propose relative inclusion criteria. Methods Thirty-five patients who underwent surgery between 2006 and 2008 were included. All patients had single-level disease and only radiculopathy. The overall sagittal balance and angle and height of a functional segmental unit (FSU; upper and lower vertebral body of the operative lesion) were assessed by preoperative and follow-up radiographs. C2–7 range of motion (ROM), FSU, and the adjacent segment were also checked. Results The clinical outcome of TDR (group A) was tended to be superior to that of PCF (group B) without statistical significance. In the group A, preoperative and postoperative upper adjacent segment level motion values were 8.6±2.3 and 8.4±2.0, and lower level motion values were 8.4±2.2 and 8.3±1.9. Preoperative and postoperative FSU heights were 37.0±2.1 and 37.1±1.8. In the group B, upper level adjacent segment motion values were 8.1±2.6 and 8.2±2.8, and lower level motion values were 6.5±3.3 and 6.3±3.1. FSU heights were 37.1±2.0 and 36.2±1.8. The postoperative FSU motion and height changes were significant (p<0.05). The patient’s satisfaction rates for surgery were 88.2% in group A and 88.8% in group B. Conclusion TDR and PCF have favorable outcomes in patients with unilateral soft disc herniation. However, patients have different biomechanical backgrounds, so the patient’s biomechanical characteristics and economic status should be understood and treated using the optimal procedure. PMID:28061490

  8. Dynamic foraminal dimensions during neck extension and rotation in fusion and artificial disc replacement: an observational study.

    PubMed

    Yeni, Yener N; Baumer, Timothy; Oravec, Daniel; Basheer, Azam; McDonald, Colin P; Bey, Michael J; Bartol, Stephen W; Chang, Victor

    2017-09-04

    Changes in the dimensions of the cervical neural foramina (CNF) are considered to be a key factor in nerve root compression and development of cervical radiculopathy. However, to what extent foraminal geometry differs between patients who underwent anterior cervical discectomy and fusion (ACDF) and those who underwent total disc arthroplasty with an artificial disc (AD) during physiological motion is largely unknown. The objective of this study is to compare CNF dimensions during physiological neck motion between ACDF and AD. This is a retrospective comparative analysis of prospectively collected, consecutive, non-randomized series of patients at a single institution. A total of 16 single-level C5-C6 ACDF (4 males, 12 females; 28-71 years) and 7 single-level C5-C6 cervical arthroplasty patients (3 males, 4 females; 38-57 years), at least 12 months after surgery (23.6±6.8 months) were included. Patient demographics, preoperative magnetic resonance imaging (MRI)-based measurements of cervical spine degeneration, and 2-year postoperative measurements of dynamic foraminal geometry were the outcome measures. Biplane x-ray images were acquired during axial neck rotation and neck extension. A computed tomography scan was also acquired from C3 to the first thoracic vertebrae. The subaxial cervical vertebrae (C3-C7) were reconstructed into three-dimensional (3D) bone models for use with model-based tracking. Foraminal height (FH) was calculated as the 3D distance between the superior point of the inferior pedicle and the inferior point of the superior pedicle using custom software. Foraminal width (FW) was similarly calculated as the 3D distance between the anterolateral aspect of the superior vertebral body inferior notch and the posterolateral aspect of the inferior vertebral body superior notch. Dynamic foraminal dimensions were quantified as the minimum (FH.Min, FW.Min), the range (FH.Range, FW.Range), and the median (FH.Med, FW.Med) of each trial and then averaged

  9. Comparison of single-level L4–L5 versus L5–S1 lumbar disc replacement: results and prognostic factors

    PubMed Central

    Bundy, Albert; Costantini, Sandro; Nena, Ugo; Finocchiaro, Francesco; Monterumici, Daniele A. Fabris

    2009-01-01

    The aim of our prospective non-randomized clinical study was to analyze operative data, short-term results, safety, efficacy, complications, and prognostic factors for single-level total lumbar disc replacement (TLDR), and to compare results between different levels (L4–L5 vs. L5–S1). Thirty-six patients with single-level L4–L5 or L5–S1 TLDR, with 1-year minimum follow-up (FU), had complete clinical [SF36, visual analog scale (VAS), Oswestry Disability Index (ODI)] and radiological data, and were included in our study. Mean FU was 38.67 ± 17.34 months. Replaced level was L4–L5 in 12 (33.3%) cases, and L5–S1 in 24 cases (66.7%). Mean age at diagnosis was 41.17 ± 7.14 years. 24 (66.7%) were females and 12 (33.3%) were males. Statistical analyses were assessed using t tests or Mann–Whitney test for continuous variables and Chi-square test or Fisher’s exact test analyses for categorical variables. Univariate linear regression and binary logistic regression analyses were utilized to evaluate the relationship between surgical outcomes and covariates (gender, age, etiology, treated level, pre-operative SF36, ODI, and VAS). Mean operative time was 147.03 ± 30.03 min. Mean hospital stay was 9.69 ± 5.39 days, and mean return to ambulation was 4.31 ± 1.17 days. At 1-year FU, patients revealed a statistical significant improvement in VAS pain (P = 0.000), ODI lumbar function (P = 0.000), and SF36 general health status (P = 0.000). Single-level TLDR is a good alternative to fusion for chronic discogenic low back pain refractory to conservative measures. Our study confirmed satisfactory clinical results for monosegmental L4–L5 and L5–S1 disc prosthesis, with no difference between the two different levels for SF36 (P = 0.217), ODI (P = 0.527), and VAS (P = 0.269). However, replacement of the L4–L5 disc is affected by an increased risk of complication (P = 0.000). There were no prognostic factors for intraoperative blood

  10. Cervical anterior hybrid technique with bi-level Bryan artificial disc replacement and adjacent segment fusion for cervical myelopathy over three consecutive segments.

    PubMed

    Chen, Jiang; Xu, Lin; Jia, Yu-Song; Sun, Qi; Li, Jin-Yu; Zheng, Chen-Ying; Bai, Chun-Xiao; Yu, Qin-Sheng

    2016-05-01

    This study aimed to assess the preliminary clinical efficacy and feasibility of the hybrid technique for multilevel cervical myelopathy. Considering the many shortcomings of traditional treatment methods for multilevel cervical degenerative myelopathy, hybrid surgery (bi-level Bryan artificial disc [Medtronic Sofamor Danek, Memphis, TN, USA] replacement and anterior cervical discectomy and fusion) should be considered. Between March 2006 and November 2012, 108 patients (68 men and 40 women, average age 45years) underwent hybrid surgery. Based on the Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and Odom's criteria, the clinical symptoms and neurological function before and after surgery were evaluated. Mean surgery duration was 90minutes, with average blood loss of 30mL. Mean follow-up duration was 36months. At the final follow-up, the mean JOA (± standard deviation) scores were significantly higher compared with preoperative values (15.08±1.47 versus 9.18±1.22; P<0.01); meanwhile, NDI values were markedly decreased (12.32±1.03 versus 42.68±1.83; P<0.01). Using Odom's criteria, the clinical outcomes were rated as excellent (76 patients), good (22 patients), fair (six patients), and poor (four patients). These findings indicate that the hybrid method provides an effective treatment for cervical myelopathy over three consecutive segments, ensuring a good clinical outcome. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Advancing the integration of hospital IT. Pitfalls and perspectives when replacing specialized software for high-risk environments with enterprise system extensions.

    PubMed

    Engelmann, Carsten; Ametowobla, Dzifa

    2017-05-17

    Planning and controlling surgical operations hugely impacts upon productivity, patient safety, and surgeons' careers. Established, specialized software for this task is being increasingly replaced by "Operating Room (OR)-modules" appended to enterprise-wide resource planning (ERP) systems. As a result, usability problems are re-emerging and require developers' attention. Systematic evaluation of the functionality and social repercussions of a global, market-leading IT business control system (SAP R3, Germany), adapted for real-time OR process steering. Field study involving document analyses, interviews, and a 73-item survey addressed to 77 qualified (> 1-year system experience) senior planning executives (end users; "planners") working in surgical departments of university hospitals. Planners reported that 57% of electronic operation requests contained contradictory information. Key screens contained clinically irrelevant areas (36 +/- 29%). Compared to the legacy system, users reported either no improvements or worse performance, in regard to co-ordination of OR stakeholders, intra-day program changes, and safety. Planners concluded that the ERP-planning module was "non-intuitive" (66%), increased planning work (56%, p=0.002), and did not impact upon either organizational mishap spectrum or frequency. Interviews evidenced intra-institutional power shifts due to increased system complexity. Planners resented e.g. a trend towards increased personal culpability for mishap. Highly complex enterprise system extensions may not be directly suited to specific process steering tasks in a high risk/low error-environment like the OR. In view of surgeons' high primary task load, the repeated call for simpler IT is an imperative for ERP extensions. System design should consider a) that current OR IT suffers from an input limitation regarding planning-relevant real-time data, and b) that there are social processes that strongly affect planning and particularly ERP use beyond

  12. Long-term clinical and radiographic outcomes of the Prestige LP artificial cervical disc replacement at 2 levels: results from a prospective randomized controlled clinical trial.

    PubMed

    Lanman, Todd H; Burkus, J Kenneth; Dryer, Randall G; Gornet, Matthew F; McConnell, Jeffrey; Hodges, Scott D

    2017-07-01

    OBJECTIVE The aim of this study was to assess long-term clinical safety and effectiveness in patients undergoing anterior cervical surgery using the Prestige LP artificial disc replacement (ADR) prosthesis to treat degenerative cervical spine disease at 2 adjacent levels compared with anterior cervical discectomy and fusion (ACDF). METHODS A prospective, randomized, controlled, multicenter FDA-approved clinical trial was conducted at 30 US centers, comparing the low-profile titanium ceramic composite-based Prestige LP ADR (n = 209) at 2 levels with ACDF (n = 188). Clinical and radiographic evaluations were completed preoperatively, intraoperatively, and at regular postoperative intervals to 84 months. The primary end point was overall success, a composite variable that included key safety and efficacy considerations. RESULTS At 84 months, the Prestige LP ADR demonstrated statistical superiority over fusion for overall success (observed rate 78.6% vs 62.7%; posterior probability of superiority [PPS] = 99.8%), Neck Disability Index success (87.0% vs 75.6%; PPS = 99.3%), and neurological success (91.6% vs 82.1%; PPS = 99.0%). All other study effectiveness measures were at least noninferior for ADR compared with ACDF. There was no statistically significant difference in the overall rate of implant-related or implant/surgical procedure-related adverse events up to 84 months (26.6% and 27.7%, respectively). However, the Prestige LP group had fewer serious (Grade 3 or 4) implant- or implant/surgical procedure-related adverse events (3.2% vs 7.2%, log hazard ratio [LHR] and 95% Bayesian credible interval [95% BCI] -1.19 [-2.29 to -0.15]). Patients in the Prestige LP group also underwent statistically significantly fewer second surgical procedures at the index levels (4.2%) than the fusion group (14.7%) (LHR -1.29 [95% BCI -2.12 to -0.46]). Angular range of motion at superior- and inferior-treated levels on average was maintained in the Prestige LP ADR group to 84 months

  13. Influence of preoperative nucleus pulposus status and radiculopathy on outcomes in mono-segmental lumbar total disc replacement: results from a nationwide registry

    PubMed Central

    2011-01-01

    Background Currently, herniated nucleus pulposus (HNP) with radiculopathy and other preconditions are regarded as relative or absolute contraindications for lumbar total disc replacement (TDR). In Switzerland it is left to the surgeon's discretion when to operate. The present study is based on the dataset of SWISSspine, a governmentally mandated health technology assessment registry. We hypothesized that preoperative nucleus pulposus status and presence or absence of radiculopathy has an influence on clinical outcomes in patients treated with mono-segmental lumbar TDR. Methods Between March 2005 and April 2009, 416 patients underwent mono-segmental lumbar TDR, which was documented in a prospective observational multicenter mode. The data collection consisted of perioperative and follow-up data (physician based) and clinical outcomes (NASS, EQ-5D). Patients were divided into four groups according to their preoperative status: 1) group degenerative disc disease ("DDD"): 160 patients without HNP and no radiculopathy, classic precondition for TDR; 2) group "HNP-No radiculopathy": 68 patients with HNP but without radiculopathy; 3) group "Stenosis": 73 patients without HNP but with radiculopathy, and 4) group "HNP-Radiculopathy": 132 patients with HNP and radiculopathy. The groups were compared regarding preoperative patient characteristics and pre- and postoperative VAS and EQ-5D scores using general linear modeling. Results Demographics in all four groups were comparable. Regarding the improvement of quality of life (EQ-5D) there were no differences across the four groups. For the two main groups DDD and HNP-Radiculopathy no differences were found in the adjusted postoperative back- and leg pain alleviation levels, in the stenosis group back- and leg pain relief were lower. Conclusions Despite higher preoperative leg pain levels, outcomes in lumbar TDR patients with HNP and radiculopathy were similar to outcomes in patients with the classic indication; this because

  14. Factors affecting reoperations after anterior cervical discectomy and fusion within and outside of a Federal Drug Administration investigational device exemption cervical disc replacement trial.

    PubMed

    Singh, Kern; Phillips, Frank M; Park, Dan K; Pelton, Miguel A; An, Howard S; Goldberg, Edward J

    2012-05-01

    The excellent clinical results of five US Federal Drug Administration (FDA) trials approved for cervical total disc replacement (TDR) (Prestige [Medtronic Sofamor Danek, Memphis, TN, USA], Bryan [Medtronic Sofamor Danek], ProDisc-C [Synthes, West Chester, PA, USA], Kineflex|C [SpinalMotion, Mountain View, CA, USA], and Mobi-C [LDR Spine, Austin, TX, USA]) have recently been published. In these prospective randomized studies, superiority or equivalency of TDR was claimed, citing an 8.7% (23/265), 9.5% (21/221), 8.5% (9/106), 12.2% (14/115), and 6.2% (5/81) (mean = 9.02%) rate of additional related cervical surgical procedures within 2 years in control anterior cervical discectomy and fusion (ACDF) patients, respectively, compared with 1.8% (5/276), 5.8% (14/242), 1.9% (2/103), 11% (15/136), and 1.2% (2/164) (mean = 4.34%) in patients receiving the cervical TDR. The rate of reoperation within 2 years after ACDF seems unusually high. To assess the rate of and specific indications for early reoperation after ACDF in a cohort of patients receiving the ACDF as part of their customary care. These results are contrasted with similar patients receiving ACDF as the control arm of five FDA investigational device exemption (IDE) studies. Multisurgeon retrospective clinical series from a single institution. One hundred seventy-six patients with spondylotic radiculopathy or myelopathy underwent ACDF by three surgeons between 2001 and 2005 as part of their clinical practices. All patients had at least 2 years of follow-up with final follow-up within 6 months of completion of this study. Cervical reoperation rates at 2-year follow-up and at 3.5-year follow-up. Review of medical records and telephone conversations were completed to determine the number of patients who had undergone a revision cervical procedure. At final follow-up, complete data were available for 159 ACDF patients. Of the 48 patients who underwent single-level ACDF and met criteria for inclusion in the IDE studies

  15. Submicron sized ultra-high molecular weight polyethylene wear particle analysis from revised SB Charité III total disc replacements.

    PubMed

    Punt, Ilona; Baxter, Ryan; van Ooij, André; Willems, Paul; van Rhijn, Lodewijk; Kurtz, Steven; Steinbeck, Marla

    2011-09-01

    Submicron sized particles are frequently observed in retrieved total hip and knee periprosthetic tissues and appear to be critical in the activation of the phagocytic inflammatory response. In this paper the concentration, size and shape of ultra-high molecular weight polyethylene (UHMWPE) wear particles between 0.05 and 2.00μm were determined after isolation from periprosthetic tissues from retrieved lumbar SB Charité III total disc replacements (TDR) using scanning electron microscopy (SEM). For comparison, UHMWPE wear particles were isolated from γ-radiation-air sterilized total hip arthroplasty (THA) revision tissues. The mean concentration of UHMWPE particles in TDR tissues was 1.6×10(9)g(-1)tissue (range 1.3-2.0), which was significantly lower than the concentration of 2.3×10(9)g(-1) THA revision tissue (range 1.8-3.2) (P=0.03). The mean particle size (equivalent circular diameter: TDR, 0.46μm; THA 0.53μm, P=0.60) and mean shape were comparable between TDR and THA (aspect ratio: TDR, 1.89; THA, 1.99, P=0.35; roundness: TDR, 0.58; THA, 0.56, P=0.35). However, the TDR particles tended to be smaller and more round. Although no correlations were found between visible damage to the UHMWPE core and the concentration or shape of the UHMWPE particles, a positive correlation was found between increasing particle size and increasing rim penetration of the TDR core (P=0.04). The presence of UHMWPE particles of similar size and shape in TDR tissue, albeit lower in concentration, might explain why, unlike THA, pain rather than osteolysis is the major reason for revision surgery. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Are periprosthetic tissue reactions observed after revision of total disc replacement comparable to the reactions observed after total hip or knee revision surgery?

    PubMed Central

    Punt, Ilona M.; Austen, Shennah; Cleutjens, Jack P.M.; Kurtz, Steven M.; ten Broeke, René H.M.; van Rhijn, Lodewijk W.; Willems, Paul C.; van Ooij, André

    2011-01-01

    Study design Comparative study. Objective To compare periprosthetic tissue reactions observed after total disc replacement (TDR), total hip arthroplasty (THA) and total knee arthroplasty (TKA) revision surgery. Summary of background data Prosthetic wear debris leading to particle disease, followed by osteolysis, is often observed after THA and TKA. Although the presence of polyethylene (PE) particles and periprosthetic inflammation after TDR has been proven recently, osteolysis is rarely observed. The clinical relevance of PE wear debris in the spine remains poorly understood. Methods Number, size and shape of PE particles, as well as quantity and type of inflammatory cells in periprosthetic tissue retrieved during Charité TDR (n=22), THA (n=10) and TKA (n=4) revision surgery were compared. Tissue samples were stained with hematoxylin/eosin and examined by using light microscopy with bright field and polarized light. Results After THA, large numbers of PE particles <6 µm were observed, which were mainly phagocytosed by macrophages. The TKA group had a broad size range with many larger PE particles and more giant cells. In TDR, the size range was similar to that observed in TKA. However, the smallest particles were the most prevalent with 75% of the particles being <6 µm, as seen in revision THA. In TDR, both macrophages and giant cells were present with a higher number of macrophages. Conclusions Both small and large PE particles are present after TDR revision surgery compatible with both THA and TKA wear patterns. The similarities between periprosthetic tissue reactions in the different groups may give more insight in the clinical relevance of PE particles and inflammatory cells in the lumbar spine. The current findings may help to improve TDR design as applied from technologies previously developed in THA and TKA with the goal of a longer survival of TDR. PMID:21336235

  17. Thirty-day readmission and reoperation rates after single-level anterior cervical discectomy and fusion versus those after cervical disc replacement.

    PubMed

    Bhashyam, Niketh; De la Garza Ramos, Rafael; Nakhla, Jonathan; Nasser, Rani; Jada, Ajit; Purvis, Taylor E; Sciubba, Daniel M; Kinon, Merritt D; Yassari, Reza

    2017-02-01

    OBJECTIVE The goal of this study was to compare 30-day readmission and reoperation rates after single-level anterior cervical discectomy and fusion (ACDF) versus those after cervical disc replacement (CDR). METHODS The authors used the 2013-2014 American College of Surgeons National Surgical Quality Improvement Program database. Included were adult patients who underwent first-time single-level ACDF or CDR for cervical spondylosis or disc herniation. Primary outcome measures were readmission and/or reoperation within 30 days of the original surgery. Logistic regression analysis was used to assess the independent effect of the procedure (ACDF or CDR) on outcome, and results are presented as odds ratios with 95% confidence intervals. RESULTS A total of 6077 patients met the inclusion criteria; 5590 (92.0%) patients underwent single-level ACDF, and 487 (8.0%) patients underwent CDR. The readmission rates were 2.6% for ACDF and 0.4% for CDR (p = 0.003). When stratified according to age groups, only patients between the ages of 41 and 60 years who underwent ACDF had a significantly higher readmission rate than those who underwent CDR (2.5% vs 0.7%, respectively; p = 0.028). After controlling for patient age, sex, body mass index, smoking status, history of chronic obstructive pulmonary disease (COPD), diabetes, hypertension, steroid use, and American Society of Anesthesiologists (ASA) class, patients who underwent CDR were significantly less likely to undergo readmission within 30 days than patients who underwent ACDF (OR 0.23 [95% CI 0.06-0.95]; p = 0.041). Patients with a history of COPD (OR 1.97 [95% CI 1.08-3.57]; p = 0.026) or hypertension (OR 1.62 [95% CI 1.10-2.38]; p = 0.013) and those at ASA Class IV (OR 14.6 [95% CI 1.69-125.75]; p = 0.015) were significantly more likely to require readmission within 30 days. The reoperation rates were 1.2% for ACDF and 0.4% for CDR (p = 0.086), and multivariate analysis revealed that CDR was not associated with lower odds of

  18. The use of a novel injectable hydrogel nucleus pulposus replacement in restoring the mechanical properties of cyclically fatigued porcine intervertebral discs.

    PubMed

    Balkovec, Christian; Vernengo, Jennifer; McGill, Stuart M

    2013-06-01

    Repeated flexion and extension of an intervertebral disc has been shown to affect the angular stiffness of spinal motion segments and is a barometer of the mechanical integrity of the disc. A degenerated disc that loses height causes higher levels of stress on the annulus and facet joints which may increase its level of degeneration; restoring disc height may therefore help to slow this degenerative cascade. Previous research has indicated that nucleus implants have the potential to improve the mechanical characteristics of a disc and an implant that is custom-fit to the intervertebral disc yields the best results with respect to decreasing annular degeneration. Two groups of porcine spinal motion segments were exposed to repeated flexion and extension. One group was then injected with a novel hydrogel while the other group was used as a control. Both groups were then exposed to another round of cyclic flexion and extension to examine the effect that the hydrogel had on restoring the original mechanics to the motion segments. Angular stiffness was restored to the group which received the hydrogel injection in addition to a significant improvement in specimen height. No significant changes were seen in the group which did not receive an injection. It would appear that use of the novel injectable hydrogel is able to restore angular stiffness to cyclically fatigued spinal motion segments. It is also important to note that continued repetition of the event causing specimen fatigue after performing hydrogel injection will result in an eventual return to the same fatigued state.

  19. Comparison of the incidence of patient-reported post-operative dysphagia between ACDF with a traditional anterior plate and artificial cervical disc replacement.

    PubMed

    Yang, Yi; Ma, Litai; Liu, Hao; Liu, Yilian; Hong, Ying; Wang, Beiyu; Ding, Chen; Deng, Yuxiao; Song, Yueming; Liu, Limin

    2016-09-01

    Compared with anterior cervical discectomy and fusion (ACDF), cervical disc replacement (CDR) has provided satisfactory clinical results. The incidence of post-operative dysphagia between ACDF with a traditional anterior plate and CDR remains controversial. Considering the limited studies and knowledge in this area, a retrospective study focusing on post-operative dysphagia was conducted. The Bazaz grading system was used to assess the severity of dysphagia at post-operative intervals including 1 week, 1 month, 3 months, 6 months, 12 months and 24 months respectively. The Chi-square test, Student t-test, Mann-Whitney U tests and Ordinal Logistic regression were used for data analysis when appropriate. Statistical significance was accepted at a probability value of <0.05. Two hundred and thirty-one patients in the CDR group and one hundred and fifty-eight patients in Plate group were included in this study. The total incidences of dysphagia in the CDR and plate group were 36.58% and 60.43% at one week, 29.27% and 38.85% at one month, 21.95% and 31.65% at three months, 6.83% and 17.99% at six months, 5.85% and 14.39% at 12 months, and 4.39% and 10.07% at the final follow-up respectively (All P<0.05, Mann-Whitney U test). Ordinal Logistic regression analysis showed that female patients, two-level surgery, C4/5 surgery, and anterior cervical plating were significant risk factors for post-operative dysphagia (all P<0.05). Comparing ACDF with a plate, CDR with a Prestige LP can significantly reduce both transient and persistent post-operative dysphagia. Female patients, two-level surgery, C4/5 surgery and anterior cervical plating were associated with a higher incidence of dysphagia. Future prospective, randomized, controlled studies are needed to further validate these findings. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Comparison between cervical total disc replacement and anterior cervical discectomy and fusion of 1 to 2 levels from 2002 to 2009.

    PubMed

    Nandyala, Sreeharsha V; Marquez-Lara, Alejandro; Fineberg, Steven J; Singh, Kern

    2014-01-01

    Retrospective database analysis. To compare the perioperative patient characteristics, early postoperative outcomes, and costs between anterior cervical discectomy and fusion (ACDF) and cervical total disc replacement (TDR) in the United States. Cervical TDR and ACDF are indicated to treat symptomatic cervical degenerative pathology. The epidemiology, complication rates, and the cost differences between the 2 surgical approaches are not well characterized. Data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project was queried from 2002 to 2009. Patients undergoing cervical TDR or ACDF of 1 to 2 levels were identified. Patient demographics, comorbidities, length of stay, costs, and the in-hospital complications were assessed. SPSS (version 20) was used for statistical analysis with χ test for categorical data and independent-samples t test for continuous data. A value of P ≤ 0.001 denoted statistical significance. Multinomial regression analysis was used to identify the independent risk for complications in the TDR cohort compared with the ACDF cohort. There were 141,230 ACDF cases of 1 to 2 levels and 1830 cervical TDR cases identified in the Nationwide Inpatient Sample database. The ACDF cohort was older and demonstrated a greater comorbidity burden than the TDR group (P < 0.001). The ACDF-treated patients demonstrated a significantly greater length of stay than the TDR group (P < 0.001). In contrast, there were no significant differences in the incidence of postoperative complications, mortality, or hospital costs between the surgical cohorts. Multinomial regression did not demonstrate significant differences in the risk for postoperative complications between the surgical techniques. The ACDF cohort was significantly older and demonstrated a greater comorbidity burden that likely contributed to the greater length of stay when than the TDR cohort. Both cohorts demonstrated comparable incidences of early postoperative complications

  1. Cross-Shear Implementation in Sliding-Distance-Coupled Finite Element Analysis of Wear in Metal-on-Polyethylene Total Joint Arthroplasty: Intervertebral Total Disc Replacement as an Illustrative Application

    PubMed Central

    Goreham-Voss, Curtis M.; Hyde, Philip J.; Hall, Richard M.; Fisher, John; Brown, Thomas D.

    2010-01-01

    Computational simulations of wear of orthopaedic total joint replacement implants have proven to valuably complement laboratory physical simulators, for pre-clinical estimation of abrasive/adhesive wear propensity. This class of numerical formulations has primarily involved implementation of the Archard/Lancaster relationship, with local wear computed as the product of (finite element) contact stress, sliding speed, and a bearing-couple-dependent wear factor. The present study introduces an augmentation, whereby the influence of interface cross-shearing motion transverse to the prevailing molecular orientation of the polyethylene articular surface is taken into account in assigning the instantaneous local wear factor. The formulation augment is implemented within a widely-utilized commercial finite element software environment (ABAQUS). Using a contemporary metal-on-polyethylene total disc replacement (ProDisc-L) as an illustrative implant, physically validated computational results are presented to document the role of cross-shearing effects in alternative laboratory consensus testing protocols. Going forward, this formulation permits systematically accounting for cross-shear effects in parametric computational wear studies of metal-on-polyethylene joint replacements, heretofore a substantial limitation of such analyses. PMID:20399432

  2. Seven PC Purchasing Pitfalls.

    ERIC Educational Resources Information Center

    Wodarz, Nan

    1997-01-01

    Explores how to avoid common pitfalls when schools purchase computer equipment. Purchasing tips are provided in the areas of choosing multiple platforms, buying the cheapest model available, choosing a proprietary design, falling for untested technology, purchasing systems that are not upgradable, ignoring extended warranties, and failing to plan…

  3. Double-level cervical total disc replacement for adjacent segment disease: is it a useful treatment? Description of late onset heterotopic ossification and review of the literature.

    PubMed

    Barbagallo, G M V; Certo, F; Visocchi, M; Sciacca, G; Albanese, V

    2014-01-01

    We report a rare case of double-level adjacent segment disease (ASD), occurring ten years later an anterior cervical discectomy (ACD) without fusion, treated by cervical arthroplasty, highlighting the outcome at long-term follow-up and focusing on heterotopic ossification. In 1995 a 25-year-old man satisfactorily underwent ACD at C4/C5. At that time MRI also showed signs of degenerative disc disease (DDD) at C3/C4 and C5/C6. Ten years later, a new MRI scan showed a large C3/C4 and a smaller C5/C6 soft disc hernia together with spondylotic changes at the level above and below the site of the first surgery. At C4/C5 imaging revealed a kyphotic stable "pseudoarthrosis" with anterior bridging osteophyte. The patient underwent double-level arthroplasty with ProDisc-C. Clinical and radiological outcome was satisfactory. 3 and 5 years after surgery, X-rays and CT scan documented the progressive development of heterotopic ossification, with gradual reduction of range of motion. A late onset heterotopic ossification can neutralize the theoretical advantages of cervical arthroplasty, which should be considered an effective surgical option only in selected cases. ACDF and restoration of normal lordosis can be a viable alternative in cervical revision surgery, as motion preservation can not be always mantained for a long time.

  4. Biomechanical changes of the lumbar segment after total disc replacement : charite(r), prodisc(r) and maverick(r) using finite element model study.

    PubMed

    Kim, Ki-Tack; Lee, Sang-Hun; Suk, Kyung-Soo; Lee, Jung-Hee; Jeong, Bi-O

    2010-06-01

    The purpose of this study was to analyze the biomechanical effects of three different constrained types of an artificial disc on the implanted and adjacent segments in the lumbar spine using a finite element model (FEM). The created intact model was validated by comparing the flexion-extension response without pre-load with the corresponding results obtained from the published experimental studies. The validated intact lumbar model was tested after implantation of three artificial discs at L4-5. Each implanted model was subjected to a combination of 400 N follower load and 5 Nm of flexion/extension moments. ABAQUS version 6.5 (ABAQUS Inc., Providence, RI, USA) and FEMAP version 8.20 (Electronic Data Systems Corp., Plano, TX, USA) were used for meshing and analysis of geometry of the intact and implanted models. Under the flexion load, the intersegmental rotation angles of all the implanted models were similar to that of the intact model, but under the extension load, the values were greater than that of the intact model. The facet contact loads of three implanted models were greater than the loads observed with the intact model. Under the flexion load, three types of the implanted model at the L4-5 level showed the intersegmental rotation angle similar to the one measured with the intact model. Under the extension load, all of the artificial disc implanted models demonstrated an increased extension rotational angle at the operated level (L4-5), resulting in an increase under the facet contact load when compared with the adjacent segments. The increased facet load may lead to facet degeneration.

  5. Biomechanical Changes of the Lumbar Segment after Total Disc Replacement : Charite®, Prodisc® and Maverick® Using Finite Element Model Study

    PubMed Central

    Kim, Ki-Tack; Lee, Sang-Hun; Suk, Kyung-Soo; Lee, Jung-Hee

    2010-01-01

    Objective The purpose of this study was to analyze the biomechanical effects of three different constrained types of an artificial disc on the implanted and adjacent segments in the lumbar spine using a finite element model (FEM). Methods The created intact model was validated by comparing the flexion-extension response without pre-load with the corresponding results obtained from the published experimental studies. The validated intact lumbar model was tested after implantation of three artificial discs at L4-5. Each implanted model was subjected to a combination of 400 N follower load and 5 Nm of flexion/extension moments. ABAQUS™ version 6.5 (ABAQUS Inc., Providence, RI, USA) and FEMAP version 8.20 (Electronic Data Systems Corp., Plano, TX, USA) were used for meshing and analysis of geometry of the intact and implanted models. Results Under the flexion load, the intersegmental rotation angles of all the implanted models were similar to that of the intact model, but under the extension load, the values were greater than that of the intact model. The facet contact loads of three implanted models were greater than the loads observed with the intact model. Conclusion Under the flexion load, three types of the implanted model at the L4-5 level showed the intersegmental rotation angle similar to the one measured with the intact model. Under the extension load, all of the artificial disc implanted models demonstrated an increased extension rotational angle at the operated level (L4-5), resulting in an increase under the facet contact load when compared with the adjacent segments. The increased facet load may lead to facet degeneration. PMID:20617091

  6. Pitfalls of nonstandardized photography.

    PubMed

    Archibald, David J; Carlson, Matthew L; Friedman, Oren

    2010-05-01

    Accurate, consistent, high-quality photographs of patients before, during, and after surgery are critical for planning and performing surgical procedures, analyzing and documenting surgical outcomes, and educating patients and surgeons. Attaining the necessary high standards of photography and avoiding common pitfalls associated with nonstandardized medical photography requires stringent uniformity in equipment, lighting, room setup, patient positioning, and camera settings. Copyright 2010 Elsevier Inc. All rights reserved.

  7. CT Colonography: Pitfalls in Interpretation

    PubMed Central

    Pickhardt, Perry J.; Kim, David H.

    2012-01-01

    Synopsis As with any radiologic imaging test, there are a number of potential interpretive pitfalls at CT colonography (CTC) that need to be recognized and handled appropriately. Perhaps the single most important step in learning to avoid most of these diagnostic traps is simply to be aware of their existence. With a little experience, most of these potential pitfalls will be easily recognized. This review will systematically cover the key pitfalls confronting the radiologist at CTC interpretation, primarily dividing them into those related to technique and those related to underlying anatomy. Tips and pointers for how to effectively handle these potential pitfalls are included. PMID:23182508

  8. Pitfalls in laparoscopic cholecystectomy.

    PubMed

    Yvergneaux, J P; Kint, M; Kuppens, E

    1994-01-01

    On the basis of literature and of 475 laparoscopic cholecystectomies of the authors, some pitfalls are reviewed. The circumstances, the mechanism and the prevention of injuries were detailed together with the connected problem of postoperative bile leakage. Among the cholangiographic pitfalls the importance of detection of congenital and acquired anomalies of the biliary tree by means of preoperative ERCP or intraoperative trans-cystic cholangiograms was emphasized. A particular study was made of 3 pictures: Mirizzi syndrome; stone impaction in Vater's papilla; no retrograde flow of the common hepatic duct on intraoperative cholangiograms. Biliodigestive fistulas were briefly commented. The problems with cystic duct stones, particularly the treatment of stones in a long, low inserted cystic duct with retroduodenal course and the closing of thick-walled or wide cystic stumps, were explained. In patients with intraoperative residual common bile duct stones and with failed preoperative catheterization of the papilla, the authors advocate their double approach technique. This combined intraoperative laparoscopic and postoperative endoscopic procedure is carried out via the same transcystic polythene catheters as used for cholangiography and external biliary drainage of the common bile duct.

  9. Intervertebral disc properties: challenges for biodevices.

    PubMed

    Costi, John J; Freeman, Brian J C; Elliott, Dawn M

    2011-05-01

    Intervertebral disc biodevices that employ motion-preservation strategies (e.g., nucleus replacement, total disc replacement and posterior stabilization devices) are currently in use or in development. However, their long-term performance is unknown and only a small number of randomized controlled trials have been conducted. In this article, we discuss the following biodevices: interbody cages, nuclear pulposus replacements, total disc replacements and posterior dynamic stabilization devices, as well as future biological treatments. These biodevices restore some function to the motion segment; however, contrary to expectations, the risk of adjacent-level degeneration does not appear to have been reduced. The short-term challenge is to replicate the complex biomechanical function of the motion segment (e.g., biphasic, viscoelastic behavior and nonlinearity) to improve the quality of motion and minimize adjacent level problems, while ensuring biodevice longevity for the younger, more active patient. Biological strategies for regeneration and repair of disc tissue are being developed and these offer exciting opportunities (and challenges) for the longer term. Responsible introduction and rigorous assessment of these new technologies are required. In this article, we will describe the properties of the disc, explore biodevices currently in use for the surgical treatment of low back pain (with an emphasis on lumbar total disc replacement) and discuss future directions for biological treatments. Finally, we will assess the challenges ahead for the next generation of biodevices designed to replace the disc.

  10. Herniated Cervical Disc

    MedlinePlus

    ... center of the disc may start to lose water content, making the disc less effective as a cushion. As a disc deteriorates, the outer layer can also tear. This can allow displacement of the disc's center (called a herniated or ...

  11. Techniques and pitfalls with the Salto prosthesis: our experience of the first 15 years.

    PubMed

    Colombier, J A; Judet, Th; Bonnin, M; Gaudot, F

    2012-12-01

    The Salto total ankle replacement system has shown to be a viable alternative in the treatment of symptomatic arthritis. However, although outcomes after total ankle replacement are promising, an exact analysis of surgical technique could help to improve them. Based on a 15 years experience with the Salto Total Ankle replacement system, the uthors discuss the surgical technique and its pitfalls, its inications and limitations in current practice.

  12. Motor neurone disease: diagnostic pitfalls.

    PubMed

    Williams, Timothy L

    2013-02-01

    The misdiagnosis of MND (particularly of the ALS phenotype), is uncommon. Atypical presentations, particularly of focal onset and with pure LMN or UMN signs, present a more difficult diagnostic challenge, although perhaps reassuringly, treatable mimics are rare. A working knowledge of potential alternative conditions and MND diagnostic pitfalls should help to reduce the misdiagnosis rate, particularly if the key points are considered.

  13. The pitfalls of container production

    Treesearch

    Wayne Bell

    2013-01-01

    This paper summarizes ten of the biggest “pitfalls” or challenges I have encountered in my experience growing southern pine seedlings in containers over the past 30 years. Learning from challenges is an important part of growing successful nursery operations.

  14. Valve assembly having remotely replaceable bearings

    DOEpatents

    Johnson, Evan R.; Tanner, David E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

  15. Analyses of the temporomandibular disc.

    PubMed

    Jirman, R; Fricová, M; Horák, Z; Krystůfek, J; Konvicková, S; Mazánek, J

    2007-01-01

    This project is the beginning of a large research work with a goal to develop a new total replacement of temporomandibular (TM) joint. First aim of this work was to determine the relative displacement of the TM disc and the mandible during mouth opening. The movement of the TM disc was studied using a magnetic resonance imaging. Sagittal static images in revolved sections of the TM joint were obtained in various positions of jaw opening from 0 to 50 mm. The results provided a description of the TM disc displacements as a function of jaw opening. The displacements of the mandible and TM disc were about 16 mm and 10 mm respectively at mouth opening of 50 mm, maximum rotation of the mandible was 34s. The results of these measurements can be used for clinical diagnostics and also they were used as inputs for the follows finite element analysis (FEA). Second aim of this work was to create stress and strain analysis of TM joint using non-linear FEA. Complex of TM joint consists of mandibular disc, half skull and half mandible during normal jaw opening. The results illustrate the stress distributions in the TMJ during a normal jaw opening.

  16. Redundant disc

    NASA Technical Reports Server (NTRS)

    Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)

    1978-01-01

    A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.

  17. Technical pitfalls of patellofemoral surgery.

    PubMed

    Gambardella, R A

    1999-10-01

    The major technical pitfalls in the performance of patellofemoral surgery stem from improper patient selection, unrealistic patient expectations, and inappropriate rehabilitation. Proper patient selection requires the physician to spend additional time in communicating with patients obtaining a comprehensive history, and performing a thorough physical examination. Patients' expectations can be realistic if appropriate time is devoted to patient education. A commitment on behalf of patients to undertake a comprehensive postoperative rehabilitation program before proceeding with any surgical procedure helps to enhance patients' success.

  18. DISC VARIANCE OF THE HARKEN MITRAL PROSTHESIS: THE CONTRIBUTION OF ASSOCIATED AORTIC REGURGITATION

    PubMed Central

    Yarnoz, Michael D.; Hueter, David; McCormick, John R.; Black, Harrison; Berger, Robert L.

    1977-01-01

    Four cases of severe mitral regurgitation due to disc variance of the Harken disc prosthesis in the mitral position are described. The valve occluder actually escaped into the left atrium in two patients, and neither survived despite emergency valve replacement. In the other two, disc malfunction was identified by flouroscopy, the prosthesis was replaced, and both patients survived. All four patients had associated aortic regurgitation, which most likely contributed to erosion of the disc edges. It is suggested that patients with the Harken disc prosthesis undergo periodic evaluation to detect abnormal disc motion. Images PMID:15216088

  19. Clinically-Relevant Cell Sources for TMJ Disc Engineering

    PubMed Central

    Johns, D.E.; Wong, M. E.; Athanasiou, K.A.

    2010-01-01

    Tissue-engineering of the temporomandibular joint (TMJ) disc aims to provide patients with TMJ disorders an option to replace diseased tissue with autologous, functional tissue. This study examined clinically-relevant cell sources by comparing costal chondrocytes, dermal fibroblasts, a mixture of the two, and TMJ disc cells in a scaffoldless tissue-engineering approach. It was hypothesized that all constructs would produce matrix relevant to the TMJ disc, but the mixture constructs were expected to appear most like the TMJ disc constructs. Costal chondrocyte and mixture constructs were morphologically and biochemically superior to the TMJ disc and dermal fibroblast constructs, and their compressive properties were not significantly different. Costal chondrocyte constructs produced almost 40 times more collagen and 800 times more glycosaminoglycans than TMJ constructs. This study demonstrates the ability of costal chondrocytes to produce extracellular matrix that may function in a TMJ disc replacement. PMID:18502963

  20. Stellar discs in Aquarius dark matter haloes

    NASA Astrophysics Data System (ADS)

    DeBuhr, Jackson; Ma, Chung-Pei; White, Simon D. M.

    2012-10-01

    We investigate the gravitational interactions between live stellar discs and their dark matter haloes, using Λ cold dark matter haloes similar in mass to that of the Milky Way taken from the Aquarius Project. We introduce the stellar discs by first allowing the haloes to respond to the influence of a growing rigid disc potential from z = 1.3 to 1.0. The rigid potential is then replaced with star particles which evolve self-consistently with the dark matter particles until z = 0.0. Regardless of the initial orientation of the disc, the inner parts of the haloes contract and change from prolate to oblate as the disc grows to its full size. When the disc's normal is initially aligned with the major axis of the halo at z = 1.3, the length of the major axis contracts and becomes the minor axis by z = 1.0. Six out of the eight discs in our main set of simulations form bars, and five of the six bars experience a buckling instability that results in a sudden jump in the vertical stellar velocity dispersion and an accompanying drop in the m = 2 Fourier amplitude of the disc surface density. The bars are not destroyed by the buckling but continue to grow until the present day. Bars are largely absent when the disc mass is reduced by a factor of 2 or more; the relative disc-to-halo mass is therefore a primary factor in bar formation and evolution. A subset of the discs is warped at the outskirts and contains prominent non-coplanar material with a ring-like structure. Many discs reorient by large angles between z = 1 and 0, following a coherent reorientation of their inner haloes. Larger reorientations produce more strongly warped discs, suggesting a tight link between the two phenomena. The origins of bars and warps appear independent: some discs with strong bars show little disturbances at the outskirts, while the discs with the weakest bars show severe warps.

  1. How Does Lumbar Degenerative Disc Disease Affect the Disc Deformation at the Cephalic Levels In Vivo?

    PubMed Central

    Wang, Shaobai; Xia, Qun; Passias, Peter; Li, Weishi; Wood, Kirkham; Li, Guoan

    2013-01-01

    level and the level one above experienced higher tensile and shear deformations during end ranges of lumbar motion in the patients with DDD before surgical treatments when compared with the healthy subjects. The larger disc deformations at the cephalic segments were otherwise not detectable using conventional magnetic resonance imaging techniques. Future studies should investigate the effect of surgical treatments, such as fusion or disc replacement, on the biomechanics of the adjacent segments during end ranges of lumbar motion. PMID:21245781

  2. Fractured occluder disc: a previously unrecognized complication of the Starr-Edwards disc prosthesis.

    PubMed

    Malouf, J F; Hannoush, H M; Odell, J A

    2001-01-01

    Fracture of the occluder disc of a low-profile Starr-Edwards prosthesis is a hitherto unrecognized complication. We describe a patient who presented with right heart failure and severe pulmonary hypertension 27 years after mitral valve replacement with a model 6520 caged-disc prosthesis. At surgery, there was a longitudinal split in the occluder disc, and organized thrombus was lodged between the split segments. This case offers a unique opportunity to study the long-term effects of wear on the polyethylene poppet and Stellite cage.

  3. Cell transplantation in lumbar spine disc degeneration disease.

    PubMed

    Hohaus, C; Ganey, T M; Minkus, Y; Meisel, H J

    2008-12-01

    Low back pain is an extremely common symptom, affecting nearly three-quarters of the population sometime in their life. Given that disc herniation is thought to be an extension of progressive disc degeneration that attends the normal aging process, seeking an effective therapy that staves off disc degeneration has been considered a logical attempt to reduce back pain. The most apparent cellular and biochemical changes attributable to degeneration include a decrease in cell density in the disc that is accompanied by a reduction in synthesis of cartilage-specific extracellular matrix components. With this in mind, one therapeutic strategy would be to replace, regenerate, or augment the intervertebral disc cell population, with a goal of correcting matrix insufficiencies and restoring normal segment biomechanics. Biological restoration through the use of autologous disc chondrocyte transplantation offers a potential to achieve functional integration of disc metabolism and mechanics. We designed an animal study using the dog as our model to investigate this hypothesis by transplantation of autologous disc-derived chondrocytes into degenerated intervertebral discs. As a result we demonstrated that disc cells remained viable after transplantation; transplanted disc cells produced an extracellular matrix that contained components similar to normal intervertebral disc tissue; a statistically significant correlation between transplanting cells and retention of disc height could displayed. Following these results the Euro Disc Randomized Trial was initiated to embrace a representative patient group with persistent symptoms that had not responded to conservative treatment where an indication for surgical treatment was given. In the interim analyses we evaluated that patients who received autologous disc cell transplantation had greater pain reduction at 2 years compared with patients who did not receive cells following their discectomy surgery and discs in patients that

  4. Fusion versus Bryan Cervical Disc in two-level cervical disc disease: a prospective, randomised study

    PubMed Central

    Nie, Lin; Zhang, Li; Hou, Yong

    2008-01-01

    In this prospective study, our aim was to compare the functional results and radiographic outcomes of fusion and Bryan Cervical Disc replacement in the treatment of two-level cervical disc disease. A total of 65 patients with two-level cervical disc disease were randomly assigned to two groups, those operated on with Bryan Cervical Disc replacement (31) and those operated on with anterior cervical fusion with an iliac crest autograft and plate (34). Clinical evaluation was carried out using the visual analogue scale (VAS), the Short Form 36 (SF-36) and the neck disability index (NDI) during a two year follow-up. Radiological evaluation sought evidence of range of motion, stability and subsidence of the prosthesis. Substantial reduction in NDI scores occurred in both groups, with greater percent improvement in the Bryan group (P = 0.023). The arm pain VAS score improvement was substantial in both groups. Bryan artificial cervical disc replacement seems reliable and safe in the treatment of patients with two-level cervical disc disease. PMID:18956190

  5. Cocking of a poppet-disc prosthesis in the aortic position. A cause of intermittent aortic regurgitation.

    PubMed

    Hammer, W J; Hearne, M J; Roberts, W C

    1976-02-01

    Intermittent aortic regurgitation due to cocking is described for the first time after replacement of the aortic valve with a poppet-disc prosthesis. A combination of disc grooving and strut thrombus produced the cocking with resultant aortic regurgitation.

  6. Turbine disc sealing assembly

    DOEpatents

    Diakunchak, Ihor S.

    2013-03-05

    A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.

  7. Revision Trabeculectomy: Pearls and Pitfalls

    PubMed Central

    Crowston, Jonathan

    2012-01-01

    ABSTRACT Revision trabeculectomy is used to describe any surgical intervention subsequent to an existing trabeculectomy. Mostly, it is used to describe resurgery for failure of trabeculectomy, as defined by inadequate pressure control. Revision may also be performed for unsafe, uncomfortable or leaking blebs. Mostly bleb failure occurs within the subconjunctival space, although the flap and ostium may be involved or causative. Clear surgical principles, meticulous surgical technique and scrupulous postoperative care are key to successful revision surgery. This review is an attempt to elucidate the technique of bleb revision for bleb failure. How to cite this article: Coote M, Crowston J. Revision Trabeculectomy: Pearls and Pitfalls. J Current Glau Prac 2012;6(3):131-138. PMID:26997769

  8. MECHANICAL DESIGN CRITERIA FOR INTERVERTEBRAL DISC TISSUE ENGINEERING

    PubMed Central

    Nerurkar, Nandan L.; Elliott, Dawn M.; Mauck, Robert L.

    2009-01-01

    Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviour, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive and shear deformations for the disc and its substructures. In some cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying measures where functional equivalence was achieved, and others where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. PMID:20080239

  9. Fibroblast Transplantation Results to the Degenerated Rabbit Lumbar Intervertebral Discs.

    PubMed

    Ural, Ibrahim Halil; Alptekin, Kerem; Ketenci, Aysegul; Solakoglu, Seyhun; Alpak, Hasan; Özyalçın, Süleyman

    2017-01-01

    Our study is an analysis of the histological and radiological changes in degenerated lumbar intervertebral discs, after transplantation of fibroblasts in rabbits. With that study we aimed to show the viability of the fibroblasts injected to the degenerated discs, and observe their potential for further studies. The apoptosis of the cell is one of the factors at the disc degeneration process. Fibroblasts may act as mesenchymal stem cells at the tissue to which they are injected and they may replace the apoptotic cells. The nucleus pulposus of the discs from eight rabbits were aspirated under scopic guidance to induce disc degeneration. One month later, cultured fibroblasts, which had been taken from the skin, were injected into the disc. The viability and the potential of the injected cells for reproduction were studied histologically and radiologically. Cellular formations and organizations indicating to the histological recovery were observed at the discs to which fibroblasts were transplanted. The histological findings of the discs to which no fibroblasts were transplanted, did not show any histological recovery. Radiologically, no finding of the improvement was found in both groups. The fibroblasts injected to the degenerated discs are viable. The findings of improvement, observed in this study, suggest that fibroblast transplantation could be an effective method of therapy for the prevention or for the retardation of the degenerative disease of the discs.

  10. Fibroblast Transplantation Results to the Degenerated Rabbit Lumbar Intervertebral Discs

    PubMed Central

    Ural, Ibrahim Halil; Alptekin, Kerem; Ketenci, Aysegul; Solakoglu, Seyhun; Alpak, Hasan; Özyalçın, Süleyman

    2017-01-01

    Background: Our study is an analysis of the histological and radiological changes in degenerated lumbar intervertebral discs, after transplantation of fibroblasts in rabbits. With that study we aimed to show the viability of the fibroblasts injected to the degenerated discs, and observe their potential for further studies. Method: The apoptosis of the cell is one of the factors at the disc degeneration process. Fibroblasts may act as mesenchymal stem cells at the tissue to which they are injected and they may replace the apoptotic cells. The nucleus pulposus of the discs from eight rabbits were aspirated under scopic guidance to induce disc degeneration. Results: One month later, cultured fibroblasts, which had been taken from the skin, were injected into the disc. The viability and the potential of the injected cells for reproduction were studied histologically and radiologically. Cellular formations and organizations indicating to the histological recovery were observed at the discs to which fibroblasts were transplanted. The histological findings of the discs to which no fibroblasts were transplanted, did not show any histological recovery. Radiologically, no finding of the improvement was found in both groups. The fibroblasts injected to the degenerated discs are viable. Conclusion: The findings of improvement, observed in this study, suggest that fibroblast transplantation could be an effective method of therapy for the prevention or for the retardation of the degenerative disease of the discs. PMID:28603572

  11. The First 18 Months Following Food and Drug Administration Approval of Lumbar Total Disc Replacement in the United States: Reported Adverse Events Outside an Investigational Device Exemption Study Environment

    PubMed Central

    Guyer, Richard D.; Geisler, Fred H.; McAfee, Paul C.; Regan, John J.

    2007-01-01

    Background Introduction of a new surgical technology may result in higher rates of adverse events compared with rates reported in the study performed to gain regulatory approval. The purpose of our study was to describe the incidence of reported adverse events during the first 18 months following US Food and Drug Administration (FDA) approval of the first lumbar arthroplasty device available in the United States and to discern data trends. Methods Reports of adverse events submitted to the FDA in patients receiving the Charité artificial disc were reviewed and pooled by similarity. We analyzed 135 medical device reports filed with the FDA regarding the Charité artificial disc between October 26, 2004, and April 26, 2006. Sixteen reports were excluded for lack of information regarding cause or because described events were vague or unrelated to the procedure. Results Rate of adverse events reported to the FDA as a percentage of devices of which the device manufacturer was aware had been dispensed at 6, 12, and 18 months following approval was 0.58%, 2.34%, and 2.13%, respectively. The adverse event reported most frequently through 18 months was anterior migration with reoperation (0.65%); other reported adverse events were, in decreasing order, sizing and malposition errors resulting in reoperation (0.36%), posterior element fracture resulting in reoperation (0.30%), major vascular injury requiring a blood transfusion (0.23%), and subsidence requiring reoperation (0.20%). Three non–device-related patient deaths were reported following FDA approval. The reported rate of sizing/malposition errors leading to reoperation of 0.36% was the same rate as that seen in the investigational device exemption (IDE) study of the Charité artificial disc. All other reported rates were lower than rates of the same events reported in the study. Conclusions Medical device reporting is an important yet highly anecdotal and incomplete event-tracking process. However, it is the

  12. ROI, Pitfalls and Best Practices with an Enterprise Smart Card Deployment

    NASA Astrophysics Data System (ADS)

    Hoyer, Philip

    This paper will describe the highlights of the ActivIdentity sponsored Datamonitor study into Return On Investment (ROI) when implementing smart cards in the enterprise in the following areas: physical and logical access convergence, remote access when replacing OTP tokens and Enterprise Single Sign-On. It also provides additional information about the pitfalls to avoid when implementing smart cards and describes best practices for deployment.

  13. Pitfalls in the performance and interpretation of clinical immunology tests.

    PubMed

    Lock, R J; Virgo, P F; Unsworth, D J

    2008-12-01

    A broad overview, with examples, of the potential pitfalls encountered in the clinical immunology laboratory is presented. Illustrative examples and case scenarios are provided from autoimmunity, immunochemistry and cellular immunology, looking at both technical and interpretative pitfalls.

  14. Reproducibility Issues: Avoiding Pitfalls in Animal Inflammation Models.

    PubMed

    Laman, Jon D; Kooistra, Susanne M; Clausen, Björn E

    2017-01-01

    In light of an enhanced awareness of ethical questions and ever increasing costs when working with animals in biomedical research, there is a dedicated and sometimes fierce debate concerning the (lack of) reproducibility of animal models and their relevance for human inflammatory diseases. Despite evident advancements in searching for alternatives, that is, replacing, reducing, and refining animal experiments-the three R's of Russel and Burch (1959)-understanding the complex interactions of the cells of the immune system, the nervous system and the affected tissue/organ during inflammation critically relies on in vivo models. Consequently, scientific advancement and ultimately novel therapeutic interventions depend on improving the reproducibility of animal inflammation models. As a prelude to the remaining hands-on protocols described in this volume, here, we summarize potential pitfalls of preclinical animal research and provide resources and background reading on how to avoid them.

  15. Menopause causes vertebral endplate degeneration and decrease in nutrient diffusion to the intervertebral discs.

    PubMed

    Wang, Yi-Xiang J; Griffith, James F

    2011-07-01

    The vasculature in the outer annulus supplies only the periphery of the disc so that nutrition to the bulk of the disc, including all the inner annulus and nucleus pulposus, is derived from the vertebral epiphyseal end arteries where nutrients diffuse across the cartilaginous endplate to reach the disc. In this regard the vertebral endplate plays an important role in disc nutrition. Compromise of diffusion of nutrients to the disc cells may play a large part in the progression or even initiation of disc degeneration. Increasing evidence suggests that estrogen deficiency also influence the severity of disc degeneration in post-menopausal females. Structural disorganization of the vertebral endplate occurs with disc degeneration, with the most common endplate changes observed clinically being Schmorl's node. Schmorl's node is more commonly seen in post-menopausal women than younger women. Osteosclerosis, osteonecrosis and fibrosis associated with Schmorl's nodes can impede nutrient diffusion into the disc as well as removal of metabolites from the disc. We hypothesize that menopause negatively affects vertebral endplate quality and induces endplate degeneration. This endplate degeneration decreases nutrients diffusion from vertebral body into discs, and also impedes removal of metabolites, leads to further disc degeneration. To confirm our hypothesis, a cross-sectional post-contrast MRI study can be performed in pre-menopausal and post-menopausal women. If the hypothesis is confirmed, then low dose hormone replacement treatment may retard disc degeneration in post menopausal women and thereby limit the consequences associated with disc degeneration such as low back pain.

  16. Ankle replacement

    MedlinePlus

    ... is surgery to replace the damaged bone and cartilage in the ankle joint. Artificial joint parts (prosthetics) ... Your surgeon will remove the damaged bone and cartilage. Your surgeon will replace the damaged part of: ...

  17. Hip Replacement

    MedlinePlus

    ... replacement is an operation in which a damaged hip joint is removed and replaced with an artificial joint. ... are many medical conditions that can damage the hip joint. (Watch the video to learn about what goes ...

  18. Pitfalls in wrist and hand ultrasound.

    PubMed

    Chiavaras, Mary M; Jacobson, Jon A; Yablon, Corrie M; Brigido, Monica Kalume; Girish, Gandikota

    2014-09-01

    The purpose of this article is to review a number of diagnostic pitfalls related to ultrasound evaluation of the hand and wrist. Such pitfalls relate to evaluation of ten-dons (extensor retinaculum, multiple tendon fascicles, tendon subluxation), inflammatory arthritis (incomplete evaluation, misinterpretation of erosions, failure to evaluate for enthesitis), carpal tunnel syndrome (inaccurate measurements, postoperative assessment), ulnar collateral ligament of the thumb (misinterpretation of the adductor aponeurosis and displaced tear), wrist ganglion cysts (incomplete evaluation and misdiagnosis), and muscle variants. Although ultrasound has been shown to be an effective imaging method for assessment of many pathologic conditions of the wrist, knowledge of potential pitfalls is essential to avoid misdiagnosis and achieve high diagnostic accuracy.

  19. [Pitfalls in the treatment of periodontitis].

    PubMed

    Casteyde, J P; Occhiminuti, M A; Achache, S; Netter, J C

    1984-01-01

    The author point out that periodontitis is a disease of multiple aetiology and indicate two types of pitfall: traps in conceiving the plan of treatment and traps in carrying out treatment. The treatment plan may be incomplete. The authors show that the deepest types of vertical alveolysis are always related to occlusal or functional imbalance and that treatment based only upon hygiene and periodontal surgery represents a pitfall. They stress the importance of functional treatment. However such complex functional treatment itself has a number of pitfalls when it is being carried out. It is essential to restore balance of the oro-facial musculature before any treatment of occlusion. These are also types of non-occlusal musculo-dental imbalance which may plan an important role in the course of periodontitis. In conclusion, the authors note that functional treatment of the manducatory apparatus is as important as controlling inflammation. This must not be underestimated nor be allowed to go unrecognised.

  20. Common problems and pitfalls in gear design

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.

    1986-01-01

    There are several pitfalls and problems associated with the successful design of a new gear transmission. A new design will require the knowledge and experience of several technical areas of engineering. Most of the pitfalls and problems associated with a new design are related to an inadequate evaluation of several areas, such as, the lubrication and cooling requirements, complete static and dynamic load analysis, evaluation of materials and heat treatment and the latest manufacturing technology. Some of the common problems of the gear design process are discussed with recommendations made for avoiding these conditions.

  1. PET/CT in the thorax: pitfalls.

    PubMed

    Truong, Mylene T; Viswanathan, Chitra; Carter, Brett W; Mawlawi, Osama; Marom, Edith M

    2014-01-01

    PET/CT is widely used in the staging and assessment of therapeutic response in patients with malignancies. Accurate interpretation of PET/CT requires knowledge of the normal physiologic distribution of [18F]-fluoro-2-deoxy-d-glucose, artifacts due to the use of CT for attenuation correction of the PET scan and potential pitfalls due to malignancies that are PET negative and benign conditions that are PET positive. Awareness of these artifacts and potential pitfalls is important in preventing misinterpretation that can alter patient management. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. [Displacement and tissue remodeling of temporomandibular joint disc].

    PubMed

    Wang, M Q

    2017-03-09

    Sounding takes the highest prevalence of the signs of temporomandibular disorders (TMD). The well accepted theory of the mechanism for temporomandibular joint (TMJ) sounding is the internal derangement typically characterized by disc displacement. However, according to literature, there are approximately one third of asymptomatic joints in population had disc displacement, and, on the other hand, there are one fourth of TMJ sounding patients had not signs or very limited signs of disc displacement. Replacing the displaced disc to the normal position via methods like surgical operation did not achieve satisfactory long-term outcomes. In this review, we discuss and analyze the possible remodeling of the joint disc displacement diagnosed with imaging based on the anatomy and pathophysiology.

  3. Holographic optical disc

    NASA Astrophysics Data System (ADS)

    Zhou, Gan; An, Xin; Pu, Allen; Psaltis, Demetri; Mok, Fai H.

    1999-11-01

    The holographic disc is a high capacity, disk-based data storage device that can provide the performance for next generation mass data storage needs. With a projected capacity approaching 1 terabit on a single 12 cm platter, the holographic disc has the potential to become a highly efficient storage hardware for data warehousing applications. The high readout rate of holographic disc makes it especially suitable for generating multiple, high bandwidth data streams such as required for network server computers. Multimedia applications such as interactive video and HDTV can also potentially benefit from the high capacity and fast data access of holographic memory.

  4. Avoiding the pitfalls of strategic planning.

    PubMed

    Clark, Cathy Sullivan; Krentz, Susanna E

    2006-11-01

    Be on guard against these and other strategic planning pitfalls: Moving to the planning stage without an environmental assessment. Developing a plan without senior management involvement. Allowing too little or too much time for planning. Using the plan simply to reinforce the status quo. Lacking clear metrics for defining strategic goals.

  5. Investigation of Product Performance of Al-Metal Matrix Composites Brake Disc using Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Fatchurrohman, N.; Marini, C. D.; Suraya, S.; Iqbal, AKM Asif

    2016-02-01

    The increasing demand of fuel efficiency and light weight components in automobile sectors have led to the development of advanced material parts with improved performance. A specific class of MMCs which has gained a lot of attention due to its potential is aluminium metal matrix composites (Al-MMCs). Product performance investigation of Al- MMCs is presented in this article, where an Al-MMCs brake disc is analyzed using finite element analysis. The objective is to identify the potentiality of replacing the conventional iron brake disc with Al-MMCs brake disc. The simulation results suggested that the MMCs brake disc provided better thermal and mechanical performance as compared to the conventional cast iron brake disc. Although, the Al-MMCs brake disc dissipated higher maximum temperature compared to cast iron brake disc's maximum temperature. The Al-MMCs brake disc showed a well distributed temperature than the cast iron brake disc. The high temperature developed at the ring of the disc and heat was dissipated in circumferential direction. Moreover, better thermal dissipation and conduction at brake disc rotor surface played a major influence on the stress. As a comparison, the maximum stress and strain of Al-MMCs brake disc was lower than that induced on the cast iron brake disc.

  6. The Complicated Facial War Injury: Pitfalls and Mismanagement.

    PubMed

    Abu-Sittah, Ghassan S; Baroud, Joe; Hakim, Christopher; Wakil, Cynthia

    2017-01-01

    The aim of this paper is to share the authors' experience in the management of complicated facial war injuries using free tissue transfer. A discussion on the most commonly encountered pitfalls in management during the acute and complicated settings is presented in an effort to raise insight on facial war wound complications. Two patients of complicated facial war injuries are presented to exemplify the pitfalls in acute and chronic management of the mandibular region in the first patient and the orbito-maxillary region in the second. The examples demonstrate free tissue transfer for early as well as late definitive reconstructions. A reconstruction algorithm or consensus regarding the optimal management plan of complicated facial war injuries is not attainable. The main principles of treatment, however, remain to decrease bacterial burden by adequate aggressive debridement followed by revisit sessions, remove of all infected hardware followed by replacement with external bony fixation if necessary and reviving the affected area by coverage with well-vascularized tissues and bone. The later is feasible via local, regional, or distant tissue transfer depending on the extent of injury, surgeon's experience, and time and personnel available. Free tissue transfer has revolutionized the management of complicated facial war injuries associated with soft tissue or bone loss as it has allowed the introduction of well-vascularized tissues into a hostile wound environment. The end result is a reduced infection rate, faster recovery time, and better functional outcome compared with when loco-regional soft tissue coverage or bone grafting is used. When soft tissue or bone loss is present, free tissue transfer should be the first management plan if time and personnel are available. The ultimate treatment of a complicated war wound remains prevention by accurate initial management.

  7. Condylar Osteochondroma Treated with Total Condylectomy and Preservation of the Articular Disc: A Case Report

    PubMed Central

    Dominguez, Manuel Fernandez; Castillo, Jose Luis Del; Guerra, Mario Muñoz; Sanchez, Ruth Sanchez; La Plata, Maria Mancha De

    2014-01-01

    Osteochondroma is frequently found in the general skeleton but is rare in the condylar region of the mandible. We report a case of an osteochondroma of large size and rapid growth in the mandibular condyle, which was treated with total condylectomy and condylar replacement with a costochondral graft and preservation of the articular disc. In cases with a healthy and well-positioned articular disc, it may be preserved with no need of disc repositioning. PMID:26000086

  8. Condylar osteochondroma treated with total condylectomy and preservation of the articular disc: a case report.

    PubMed

    Dominguez, Manuel Fernandez; Castillo, Jose Luis Del; Guerra, Mario Muñoz; Sanchez, Ruth Sanchez; La Plata, Maria Mancha De

    2015-06-01

    Osteochondroma is frequently found in the general skeleton but is rare in the condylar region of the mandible. We report a case of an osteochondroma of large size and rapid growth in the mandibular condyle, which was treated with total condylectomy and condylar replacement with a costochondral graft and preservation of the articular disc. In cases with a healthy and well-positioned articular disc, it may be preserved with no need of disc repositioning.

  9. Diagnostic pitfalls in fetal brain MRI.

    PubMed

    Al-Mukhtar, Ali; Kasprian, Gregor; Schmook, Maria T; Brugger, Peter C; Prayer, Daniela

    2009-08-01

    Recent technological advances in fetal magnetic resonance imaging (MRI) and increased reliability of MRI in depicting abnormalities and lesions, especially in the central nervous system, are increasingly bringing up challenging issues with regard to accurate diagnosis. There are also pitfalls not only attributable to image acquisition but also in clinical interpretation. The misinterpretation of findings because of insufficient knowledge about fetal brain development as visualized by MRI may also be regarded as an important limitation of fetal MRI. We provide an overview of the most common pitfalls experienced in fetal MRI in routine practice, demonstrate how to identify some of the factors that lead to imaging misinterpretation, and suggest ways to tackle these problems, with an emphasis on MR techniques and image calibration.

  10. Immunohistochemistry for Pathologists: Protocols, Pitfalls, and Tips

    PubMed Central

    Kim, So-Woon; Roh, Jin; Park, Chan-Sik

    2016-01-01

    Immunohistochemistry (IHC) is an important auxiliary method for pathologists in routine diagnostic work as well as in basic and clinical research including exploration of biomarkers, as IHC allows confirmation of target molecule expressions in the context of microenvironment. Although there has been a considerable progress in automation and standardization of IHC, there are still many things to be considered in proper optimization and appropriate interpretation. In this review, we aim to provide possible pitfalls and useful tips for practicing pathologists and residents in pathology training. First, general procedure of IHC is summarized, followed by pitfalls and tips in each step and a summary of troubleshooting. Second, ways to an accurate interpretation of IHC are discussed, with introduction to general quantification and analysis methods. This review is not intended to provide complete information on IHC, but to be used as a basic reference for practice and publication. PMID:27809448

  11. Pitfalls of predicting complex traits from SNPs

    PubMed Central

    Wray, Naomi R.; Yang, Jian; Hayes, Ben J.; Price, Alkes L.; Goddard, Mike E.; Visscher, Peter M.

    2014-01-01

    The success of genome-wide association studies has led to increasing interest in making predictions of complex trait phenotypes including disease from genotype data. Rigorous assessment of the value of predictors is critical before implementation. Here we discuss some of the limitations and pitfalls of prediction analysis and show how naïve implementations can lead to severe bias and misinterpretation of results. PMID:23774735

  12. Newborn metabolic screening and related pitfalls.

    PubMed

    Eddy, Mark; Gottesman, Gary S

    2009-01-01

    Newborn screening has recently been transformed by our enhanced knowledge of medical disorders and our ability to detect and manage them. The Missouri State Newborn Screening Laboratory incorporated tandem mass spectrometry into the newborn screening protocol in 2005. This review will highlight the new capabilities of the newborn screening laboratory and the pitfalls of screening related to preterm birth, blood transfusion and intravenous fluid administration that complicate the interpretation of screening results.

  13. The origin of thick discs

    NASA Astrophysics Data System (ADS)

    Comerón, Sébastien

    2015-03-01

    Thick discs are defined to be disc-like components with a scale height larger than that of the classical discs. They are ubiquitous (Yoachim & Dalcanton 2006; Comerón et al. 2011a), they are made of mostly old and metal-poor stars and are most easily detected in close to edge-on galaxies. Their origin has been considered mysterious and several formation theories have been proposed: • The thick disc being formed secularly by thin disc stars heated by disc overdensities such as giant molecular clouds or spiral arms (Villumsen 1985, ApJ, 290, 75) and by stars moved outwards from their original orbits by radial migration mechanisms (Schönrich & Binney 2009). • The thick disc being formed by the heating of the thin disc by satellites (Quinn et al. 1993) and the tidal stripping of them (Abadi et al. 2003). • The thick disc being formed fast and already thick at high redshift in an highly unstable disc. Inside that thick disc, a thin disc would form afterwards as suggested by Elemgreen & Elmegreen (2006). • The thick disc being formed originally thick at high redshift by the merger of gas-rich protogalactic fragments and a thin disc forming afterwards within it (Brook et al. 2007). The first mechanism is a secular evolution mechanism. The time-scale of the second one is dependent on the merger history of the main galaxy. In the two last mechanisms, the thick disc forms already thick in a short time-scale at high redshift. Recent Milky Way studies, (see, e.g., Bovy et al. 2012), have shown indications that there is no discontinuity between the thin and the thick disc chemical and kinematic properties. Instead, those studies indicate the presence of a monotonic distribution of disc thicknesses. This would suggest a secular origin for the Milky Way thick disc. Studies in external galaxies (Yoachim & Dalcanton 2006; Comerón et al. 2011b), have shown that low-mass disc galaxies have thick disc relative masses much larger than those found in large-mass galaxies

  14. Shoulder replacement

    MedlinePlus

    ... the opening at the end of the shoulder blade, called the socket. This type of joint allows ... head. The socket part (glenoid) of your shoulder blade will be replaced with a smooth plastic shell ( ...

  15. Pearls and pitfalls in neural CGRP immunohistochemistry.

    PubMed

    Warfvinge, Karin; Edvinsson, Lars

    2013-06-01

    This review outlines the pearls and pitfalls of calcitonin-gene related protein (CGRP) immunohistochemistry of the brain. In 1985, CGRP was first described in cerebral arteries using immunohistochemistry. Since then, cerebral CGRP (and, using novel antibodies, its receptor components) has been widely scrutinized. Here, we describe the distribution of cerebral CGRP and pay special attention to the surprising reliability of results over time. Pitfalls might include a fixation procedure, antibody clone and dilution, and interpretation of results. Standardization of staining protocols and true quantitative methods are lacking. The use of computerized image analysis has led us to believe that our examination is objective. However, in the steps of performing such an analysis, we make subjective choices. By pointing out these pitfalls, we aim to further improve immunohistochemical quality. Having a clear picture of the tissue/cell morphology is a necessity. A primary morphological evaluation with, for example, hematoxylin-eosin, helps to ensure that small changes are not missed and that background and artifactual changes, which may include vacuoles, pigments, and dark neurons, are not over-interpreted as compound-related changes. The antigen-antibody reaction appears simple and clear in theory, but many steps might go wrong. Remember that methods including the antigen-antibody complex rely on handling/fixation of tissues or cells, antibody shipping/storing issues, antibody titration, temperature/duration of antibody incubation, visualization of the antibody and interpretation of the results. Optimize staining protocols to the material you are using.

  16. Kozai-Lidov disc instability

    NASA Astrophysics Data System (ADS)

    Lubow, Stephen H.; Ogilvie, Gordon I.

    2017-08-01

    Recent results by Martin et al. showed in 3D smoothed particle hydrodynamics simulations that tilted discs in binary systems can be unstable to the development of global, damped Kozai-Lidov (KL) oscillations in which the discs exchange tilt for eccentricity. We investigate the linear stability of KL modes for tilted inviscid discs under the approximations that the disc eccentricity is small and the disc remains flat. By using 1D equations, we are able to probe regimes of large ratios of outer to inner disc edge radii that are realistic for binary systems of hundreds of astronomical unit separations and are not easily probed by multidimensional simulations. For order unity binary mass ratios, KL instability is possible for a window of disc aspect ratios H/r in the outer parts of a disc that roughly scale as (nb/n)2 ≲ H/r ≲ nb/n, for binary orbital frequency nb and orbital frequency n at the disc outer edge. We present a framework for understanding the zones of instability based on the determination of branches of marginally unstable modes. In general, multiple growing eccentric KL modes can be present in a disc. Coplanar apsidal-nodal precession resonances delineate instability branches. We determine the range of tilt angles for unstable modes as a function of disc aspect ratio. Unlike the KL instability for free particles that involves a critical (minimum) tilt angle, disc instability is possible for any non-zero tilt angle depending on the disc aspect ratio.

  17. The Galactic stellar disc

    NASA Astrophysics Data System (ADS)

    Feltzing, S.; Bensby, T.

    2008-12-01

    The study of the Milky Way stellar discs in the context of galaxy formation is discussed. In particular, we explore the properties of the Milky Way disc using a new sample of about 550 dwarf stars for which we have recently obtained elemental abundances and ages based on high-resolution spectroscopy. For all the stars we also have full kinematic information as well as information about their stellar orbits. We confirm results from previous studies that the thin and the thick discs have distinct abundance patterns. But we also explore a larger range of orbital parameters than what has been possible in our previous studies. Several new results are presented. We find that stars that reach high above the Galactic plane and have eccentric orbits show remarkably tight abundance trends. This implies that these stars formed out of well-mixed gas that had been homogenized over large volumes. We find some evidence that suggest that the event that most likely caused the heating of this stellar population happened a few billion years ago. Through a simple, kinematic exploration of stars with super-solar [Fe/H], we show that the solar neighbourhood contains metal-rich, high velocity stars that are very likely associated with the thick disc. Additionally, the HR1614 moving group and the Hercules and Arcturus stellar streams are discussed and it is concluded that, probably, a large fraction of the groups and streams so far identified in the disc are the result of evolution and interactions within the stellar disc rather than being dissolved stellar clusters or engulfed dwarf galaxies. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. Also based on observations collected at the Nordic Optical Telescope on La Palma, Spain, and at the European Southern Observatories on La Silla and Paranal, Chile, Proposals no. 65.L-0019(B), 67.B-0108(B), 69.B-0277.

  18. Cervical disc arthroplasty: Pros and cons

    PubMed Central

    Moatz, Bradley; Tortolani, P. Justin

    2012-01-01

    Background: Cervical disc arthroplasty has emerged as a promising potential alternative to anterior cervical discectomy and fusion (ACDF) in appropriately selected patients. Despite a history of excellent outcomes after ACDF, the question as to whether a fusion leads to adjacent segment degeneration remains unanswered. Numerous US investigational device exemption trials comparing cervical arthroplasty to fusion have been conducted to answer this question. Methods: This study reviews the current research regarding cervical athroplasty, and emphasizes both the pros and cons of arthroplasty as compared with ACDF. Results: Early clinical outcomes show that cervical arthroplasty is as effective as the standard ACDF. However, this new technology is also associated with an expanding list of novel complications. Conclusion: Although there is no definitive evidence that cervical disc replacement reduces the incidence of adjacent segment degeneration, it does show other advantages; for example, faster return to work, and reduced need for postoperative bracing. PMID:22905327

  19. Biomechanics of a Fixed–Center of Rotation Cervical Intervertebral Disc Prosthesis

    PubMed Central

    Crawford, Neil R.; Baek, Seungwon; Sawa, Anna G.U.; Safavi-Abbasi, Sam; Sonntag, Volker K.H.; Duggal, Neil

    2012-01-01

    Background Past in vitro experiments studying artificial discs have focused on range of motion. It is also important to understand how artificial discs affect other biomechanical parameters, especially alterations to kinematics. The purpose of this in vitro investigation was to quantify how disc replacement with a ball-and-socket disc arthroplasty device (ProDisc-C; Synthes, West Chester, Pennsylvania) alters biomechanics of the spine relative to the normal condition (positive control) and simulated fusion (negative control). Methods Specimens were tested in multiple planes by use of pure moments under load control and again in displacement control during flexion-extension with a constant 70-N compressive follower load. Optical markers measured 3-dimensional vertebral motion, and a strain gauge array measured C4-5 facet loads. Results Range of motion and lax zone after disc replacement were not significantly different from normal values except during lateral bending, whereas plating significantly reduced motion in all loading modes (P < .002). Plating but not disc replacement shifted the location of the axis of rotation anteriorly relative to the intact condition (P < 0.01). Coupled axial rotation per degree of lateral bending was 25% ± 48% greater than normal after artificial disc replacement (P = .05) but 37% ± 38% less than normal after plating (P = .002). Coupled lateral bending per degree of axial rotation was 37% ± 21% less than normal after disc replacement (P < .001) and 41% ± 36% less than normal after plating (P = .001). Facet loads did not change significantly relative to normal after anterior plating or arthroplasty, except that facet loads were decreased during flexion in both conditions (P < .03). Conclusions In all parameters studied, deviations from normal biomechanics were less substantial after artificial disc placement than after anterior plating. PMID:25694869

  20. Esophageal replacement.

    PubMed

    Kunisaki, Shaun M; Coran, Arnold G

    2017-04-01

    This article focuses on esophageal replacement as a surgical option for pediatric patients with end-stage esophageal disease. While it is obvious that the patient׳s own esophagus is the best esophagus, persisting with attempts to retain a native esophagus with no function and at all costs are futile and usually detrimental to the overall well-being of the child. In such cases, the esophagus should be abandoned, and the appropriate esophageal replacement is chosen for definitive reconstruction. We review the various types of conduits used for esophageal replacement and discuss the unique advantages and disadvantages that are relevant for clinical decision-making. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  2. The Chemistry of Optical Discs.

    ERIC Educational Resources Information Center

    Birkett, David

    2002-01-01

    Explains the chemistry used in compact discs (CD), digital versatile discs (DVD), and magneto-optical (MO) discs focusing on the steps of initial creation of the mold, the molding of the polycarbonate, the deposition of the reflective layers, the lacquering of the CDs, and the bonding of DVDs. (Contains 15 references.) (YDS)

  3. Revival of the Jumping Disc

    ERIC Educational Resources Information Center

    Ucke, C.; Schlichting, H-J.

    2009-01-01

    Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…

  4. How do accretion discs break?

    NASA Astrophysics Data System (ADS)

    Dogan, Suzan

    2016-07-01

    Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.

  5. The DISC Quotient

    NASA Astrophysics Data System (ADS)

    Elliott, John R.; Baxter, Stephen

    2012-09-01

    D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

  6. Herniated Lumbar Disc

    MedlinePlus

    ... at and just below the waist. A herniated lumbar disc can press on the nerves in the spine and may cause pain, numbness, ... point injections do not help heal a herniated lumbar ... on and irritating the nerves, causing symptoms of pain and weakness. The most ...

  7. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  8. Hybrid cervical disc arthroplasty.

    PubMed

    Tu, Tsung-Hsi; Wu, Jau-Ching; Cheng, Henrich; Mummaneni, Praveen V

    2017-01-01

    For patients with multilevel cervical stenosis at nonadjacent segments, one of the traditional approaches has included a multilevel fusion of the abnormal segments as well as the intervening normal segment. In this video we demonstrate an alternative treatment plan with tailored use of a combination of anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) with an intervening skipped level. The authors present the case of a 72-year-old woman with myeloradiculopathy and a large disc herniation with facet joint degeneration at C3-4 and bulging disc at C5-6. After nonoperative treatment failed, she underwent a single-level ACDF at C3-4 and single-level arthroplasty at C5-6, which successfully relieved her symptoms. No intervention was performed at the normal intervening C4-5 segment. By using ACDF combined with arthroplasty, the authors have avoided a 3-level fusion for this patient and maintained the range of motion of 2 disc levels. The video can be found here: https://youtu.be/OrxcPUBvqLk .

  9. The Teddy Bears' Disc.

    ERIC Educational Resources Information Center

    Laurillard, Diana

    1985-01-01

    Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)

  10. Planet-disc interaction in laminar and turbulent discs

    NASA Astrophysics Data System (ADS)

    Stoll, Moritz H. R.; Picogna, Giovanni; Kley, Wilhelm

    2017-07-01

    In weakly ionised discs turbulence can be generated through the vertical shear instability (VSI). Embedded planets are affected by a stochastic component in the torques acting on them, which can impact their migration. In this work we study the interplay between a growing planet embedded in a protoplanetary disc and the VSI turbulence. We performed a series of 3D hydrodynamical simulations for locally isothermal discs with embedded planets in the mass range from 5 to 100 Earth masses. We study planets embedded in an inviscid disc that is VSI unstable, becomes turbulent, and generates angular momentum transport with an effective α = 5 × 10-4. This is compared to the corresponding viscous disc using exactly this α-value. In general we find that the planets have only a weak impact on the disc turbulence. Only for the largest planet (100 M⊕) does the turbulent activity become enhanced inside of the planet. The depth and width of a gap created by the more massive planets (30,100 M⊕) in the turbulent disc equal exactly that of the corresponding viscous case, leading to very similar torque strengths acting on the planet, with small stochastic fluctuations for the VSI disc. At the gap edges vortices are generated that are stronger and longer-lived in the VSI disc. Low mass planets (with Mp ≤ 10 M⊕) do not open gaps in the disc in either case, but generate for the turbulent disc an overdensity behind the planet that exerts a significant negative torque. This can boost the inward migration in VSI turbulent discs well above the Type I rate. Owing to the finite turbulence level in realistic 3D discs the gap depth will always be limited and migration will not stall in inviscid discs.

  11. Pitfalls of Personal Development Plans--The User Perspective

    ERIC Educational Resources Information Center

    Grohnert, Therese; Beausaert, Simon; Segers, Mien

    2014-01-01

    This study was conducted to investigate which pitfalls users of personal development plans (PDPs) perceive in business and governmental organisations with mandatory PDP use. Hundred and thirty-one written statements of PDP users across three Dutch organisations were analysed and categorised into nine pitfalls. Next to an overall lack of use and…

  12. Pitfalls of Personal Development Plans--The User Perspective

    ERIC Educational Resources Information Center

    Grohnert, Therese; Beausaert, Simon; Segers, Mien

    2014-01-01

    This study was conducted to investigate which pitfalls users of personal development plans (PDPs) perceive in business and governmental organisations with mandatory PDP use. Hundred and thirty-one written statements of PDP users across three Dutch organisations were analysed and categorised into nine pitfalls. Next to an overall lack of use and…

  13. Applied statistics in ecology: common pitfalls and simple solutions

    Treesearch

    E. Ashley Steel; Maureen C. Kennedy; Patrick G. Cunningham; John S. Stanovick

    2013-01-01

    The most common statistical pitfalls in ecological research are those associated with data exploration, the logic of sampling and design, and the interpretation of statistical results. Although one can find published errors in calculations, the majority of statistical pitfalls result from incorrect logic or interpretation despite correct numerical calculations. There...

  14. 26 CFR 1.6011-2 - Returns, etc., of DISC's and former DISC's.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 13 2011-04-01 2011-04-01 false Returns, etc., of DISC's and former DISC's. 1...., of DISC's and former DISC's. (a) Records and information. Every DISC and former DISC (as defined in..., statements, and special returns. Thus, for example, a DISC is required to maintain the books of account or...

  15. ISASS Policy Statement – Lumbar Artificial Disc

    PubMed Central

    Garcia, Rolando

    2015-01-01

    Purpose The primary goal of this Policy Statement is to educate patients, physicians, medical providers, reviewers, adjustors, case managers, insurers, and all others involved or affected by insurance coverage decisions regarding lumbar disc replacement surgery. Procedures This Policy Statement was developed by a panel of physicians selected by the Board of Directors of ISASS for their expertise and experience with lumbar TDR. The panel's recommendation was entirely based on the best evidence-based scientific research available regarding the safety and effectiveness of lumbar TDR. PMID:25785243

  16. Pitfalls in colour photography of choroidal tumours

    PubMed Central

    Schalenbourg, A; Zografos, L

    2013-01-01

    Colour imaging of fundus tumours has been transformed by the development of digital and confocal scanning laser photography. These advances provide numerous benefits, such as panoramic images, increased contrast, non-contact wide-angle imaging, non-mydriatic photography, and simultaneous angiography. False tumour colour representation can, however, cause serious diagnostic errors. Large choroidal tumours can be totally invisible on angiography. Pseudogrowth can occur because of artefacts caused by different methods of fundus illumination, movement of reference blood vessels, and flattening of Bruch's membrane and sclera when tumour regression occurs. Awareness of these pitfalls should prevent the clinician from misdiagnosing tumours and wrongfully concluding that a tumour has grown. PMID:23238442

  17. Pitfalls in colour photography of choroidal tumours.

    PubMed

    Schalenbourg, A; Zografos, L

    2013-02-01

    Colour imaging of fundus tumours has been transformed by the development of digital and confocal scanning laser photography. These advances provide numerous benefits, such as panoramic images, increased contrast, non-contact wide-angle imaging, non-mydriatic photography, and simultaneous angiography. False tumour colour representation can, however, cause serious diagnostic errors. Large choroidal tumours can be totally invisible on angiography. Pseudogrowth can occur because of artefacts caused by different methods of fundus illumination, movement of reference blood vessels, and flattening of Bruch's membrane and sclera when tumour regression occurs. Awareness of these pitfalls should prevent the clinician from misdiagnosing tumours and wrongfully concluding that a tumour has grown.

  18. LUMBAR DISC HERNIATION

    PubMed Central

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  19. Mechanotransduction in intervertebral discs

    PubMed Central

    Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang

    2014-01-01

    Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492

  20. Biomechanics of Disc Degeneration

    PubMed Central

    Palepu, V.; Kodigudla, M.; Goel, V. K.

    2012-01-01

    Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the “gold standard” in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914

  1. Arrhythmogenic cardiomyopathy: a disease of intercalated discs.

    PubMed

    Calore, Martina; Lorenzon, Alessandra; De Bortoli, Marzia; Poloni, Giulia; Rampazzo, Alessandra

    2015-06-01

    Arrhythmogenic cardiomyopathy (ACM) is an acquired progressive disease having an age-related penetrance and showing clinical manifestations usually during adolescence and young adulthood. It is characterized clinically by a high incidence of severe ventricular tachyarrhythmias and sudden cardiac death and pathologically by degeneration of ventricular cardiomyocytes with replacement by fibro-fatty tissue. Whereas, in the past, the disease was considered to involve only the right ventricle, more recent clinical studies have established that the left ventricle is frequently involved. ACM is an inherited disease in up to 50% of cases, with predominantly an autosomal dominant pattern of transmission, although recessive inheritance has also been described. Since most of the pathogenic mutations have been identified in genes encoding desmosomal proteins, ACM is currently defined as a disease of desmosomes. However, on the basis of the most recent description of the intercalated disc organization and of the identification of a novel ACM gene encoding for an area composita protein, ACM can be considered as a disease of the intercalated disc, rather than only as a desmosomal disease. Despite increasing knowledge of the genetic basis of ACM, we are just beginning to understand early molecular events leading to cardiomyocyte degeneration, fibrosis and fibro-fatty substitution. This review summarizes recent advances in our comprehension of the link between the molecular genetics and pathogenesis of ACM and of the novel role of cardiac intercalated discs.

  2. Validated finite element analysis of the maverick total disc prosthesis.

    PubMed

    Le Huec, Jean-Charles; Lafage, Virginie; Bonnet, Xavier; Lavaste, François; Josse, Loic; Liu, Minglyan; Skalli, Wafa

    2010-06-01

    Combining in vitro tests and finite element analysis to provide a more complete picture of the role that a disc prosthesis implant would play in the biomechanics of the spine. Analysis of the disc function after total disc prosthesis insertion with and without antero-posterior or lateral offset and in combination with adjacent fusion. To avoid the risk of degenerative cascade the total disc replacement may be considered as an alternative. Few finite element analysis combined with cadaver testing under loading conditions have been published today. In vitro tests were performed using 6 fresh human cadaver specimens to quantify the load-displacement behaviors before and after insertion of a total disc replacement (Maverick, Memphis) implant. A finite element (FE) spine model was validated with the data from the in vitro tests. This model is built on the basis of ANSYS software. The effect of the prosthesis positioning on the motion behavior at L4-L5 and on the inner loads over facets was evaluated in 4 configurations. The study showed that the motion behavior at the levels adjacent to the Maverick prosthesis remained the same as the intact spine, unlike a single level fusion at L5-S1. In the biomechanical study settings, Maverick prosthesis, once properly positioned, does not modify the motion behavior of the spine as compared with its intact state. The less-than-ideal positioning of the prosthesis, especially with anterior offset, affect significantly the range of motion of the spine segment and cause increase of inner load in the facets. Those results indicated a good reliability of the finite element model in representing both intact and instrumented spine segments. The in vitro test results demonstrated that Maverick disc prosthesis provides near physiologic function of a natural disc restores stability of the spine and preserves the segmental motion without undue stress on adjacent segments.To our knowledge, this study suggested for the first time the importance

  3. Mechanics of Actuated Disc Cutting

    NASA Astrophysics Data System (ADS)

    Dehkhoda, Sevda; Detournay, Emmanuel

    2017-02-01

    This paper investigates the mechanics of an actuated disc cutter with the objective of determining the average forces acting on the disc as a function of the parameters characterizing its motion. The specific problem considered is that of a disc cutter revolving off-centrically at constant angular velocity around a secondary axis rigidly attached to a cartridge, which is moving at constant velocity and undercutting rock at a constant depth. This model represents an idealization of a technology that has been implemented in a number of hard rock mechanical excavators with the goal of reducing the average thrust force to be provided by the excavation equipment. By assuming perfect conformance of the rock with the actuated disc as well as a prescribed motion of the disc (perfectly rigid machine), the evolution of the contact surface between the disc and the rock during one actuation of the disc can be computed. Coupled with simple cutter/rock interaction models that embody either a ductile or a brittle mode of fragmentation, these kinematical considerations lead to an estimate of the average force on the cartridge and of the partitioning of the energy imparted by the disc to the rock between the actuation mechanism of the disc and the translation of the cartridge on which the actuated disc is attached.

  4. Estrogens and the intervertebral disc.

    PubMed

    Calleja-Agius, J; Muscat-Baron, Y; Brincat, M P

    2009-09-01

    Intervertebral discs are an integral part of the vertebral column. It has been shown that menopause has a negative effect on bone and on intervertebral discs. Estrogen has a beneficial effect of preserving the health of collagen-containing tissues, including the intervertebral disc. The intervertebral disc allows for mobility of the spine, and maintains a uniform stress distribution of the area of the vertebral endplates. Also, the disc influences spinal height. The disc tissue is adapted for this biomechanical function. The function of the spine is impaired if there is a loss of disc tissue. Narrowing of the disc space due to degeneration of intervertebral discs is associated with a significantly increased risk of vertebral fractures. Estrogen should be seen as the first-choice therapy for bones and other collagen-rich tissues, such as intervertebral discs, because it maintains homeostasis of the bone-remodelling unit. Unlike bisphosphonates, estrogen is unique in its ability to regenerate bone collagen after its disintegration, apart from suppressing osteoclastic activity. Besides, there is insufficient data on deterioration in bone qualities and micro-cracks in patients on long-term bisphosphonates.

  5. Polarimetric microlensing of circumstellar discs

    NASA Astrophysics Data System (ADS)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  6. Disc-mass distribution in star-disc encounters

    NASA Astrophysics Data System (ADS)

    Steinhausen, M.; Olczak, C.; Pfalzner, S.

    2012-02-01

    Aims: Investigations of stellar encounters in cluster environments have demonstrated their potential influence on the mass and angular momentum of protoplanetary discs around young stars. We investigated how far the initial surface density in the disc surrounding a young star influences the outcome of an encounter. Methods: The numerical method applied here allows us to determine the mass and angular momentum losses in an encounter for any initial disc-mass distribution. On the basis of a power-law ansatz for the surface density, Σ(r) ∝ r - p, we perform a parameter study of star-disc encounters with different initial disc-mass distributions using N-body simulations. Results: We demonstrate that the shape of the disc-mass distribution has a significant impact on the quantity of the disc-mass and angular momentum losses in star-disc encounters. In particular, the results are most sensitive to how the outer parts of the disc are perturbed by high-mass stars. In contrast, disc-penetrating encounters lead more or less independently of the disc-mass distribution always to large losses. However, maximum losses are generally obtained for initially flat distributed disc material. Based on a parameter study, a fit formula is derived, describing how the relative mass and angular momentum loss depend on the initial disc-mass distribution index p. Encounters generally lead to a steepening of the density profile of the disc. The resulting profiles can have a r-2-dependence or an even steeper one that is independent of the initial distribution of the disc material. Conclusions: From observations, the initial density distribution in discs remains unconstrained, hence the strong dependence on the initial density distribution that we find here might require a revision of the effect of encounters in young stellar clusters. The steep surface density distributions induced by some encounters might be a prerequisite to the formation of planetary systems similar to our own Solar

  7. Spinal osteotomies: indications, limits and pitfalls

    PubMed Central

    Kose, Kamil Cagri; Bozduman, Omer; Yenigul, Ali Erkan; Igrek, Servet

    2017-01-01

    The aims of spinal deformity surgery are to achieve balance, relieve pain and prevent recurrence or worsening of the deformity. The main types of osteotomies are the Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy (PSO), bone-disc-bone osteotomy (BDBO) and vertebral column resection (VCR), in order of increasing complexity. SPO is a posterior column osteotomy in which the posterior ligaments and the facet joints are removed and correction is performed through the disc space. A mobile anterior disc is essential. SPO is best in patients with +6-8 cm C7 plumbline. The amount of correction is 9.3° to 10.7°/level (1°/mm bone). PSO is a technique where the posterior elements and pedicles are removed. Then a triangular wedge through the pedicles is removed and the posterior spine is shortened using the anterior cortex as a hinge. The ideal candidates are patients with a severe sagittal imbalance. A single level osteotomy can produce 30° 40° of correction. A single level osteotomy may restore global sagittal balance by an average of 9 cm with an upper limit of 19 cm. BDBO is an osteotomy done above and below a disc level. A BDBO provides correction rates in the range of 35° to 60°. The main indications are deformities with the disc space as the apex and severe sagittal plane deformities. VCR is indicated for rigid multi-planar deformities, sharp angulated deformities, hemivertebra resections, resectable spinal tumours, post-traumatic deformities and spondyloptosis. The main indication for a VCR is fixed coronal plane deformity. The type of osteotomy must be chosen mainly according to the aetiology, type and apex of the deformity. One may start with SPOs and may gradually advance to complex osteotomies. Cite this article: EFORT Open Rev 2017;2:73-82. DOI: 10.1302/2058-5241.2.160069 PMID:28507779

  8. Rethinking Black Hole Accretion Discs

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg

    Accretion discs are staples of astrophysics. Tapping into the gravitational potential energy of the accreting material, these discs are highly efficient machines that produce copious radiation and extreme outflows. While interesting in their own right, accretion discs also act as tools to study black holes and directly influence the properties of the Universe. Black hole X-ray binaries are fantastic natural laboratories for studying accretion disc physics and black hole phenomena. Among many of the curious behaviors exhibited by these systems are black hole state transitions -- complicated cycles of dramatic brightening and dimming. Using X-ray observations with high temporal cadence, we show that the evolution of the accretion disc spectrum during black hole state transitions can be described by a variable disc atmospheric structure without invoking a radially truncated disc geometry. The accretion disc spectrum can be a powerful diagnostic for measuring black hole spin if the effects of the disc atmosphere on the emergent spectrum are well-understood; however, properties of the disc atmosphere are largely unconstrained. Using statistical methods, we decompose this black hole spin measurement technique and show that modest uncertainties regarding the disc atmosphere can lead to erroneous spin measurements. The vertical structure of the disc is difficult to constrain due to our ignorance of the contribution to hydrostatic balance by magnetic fields, which are fundamental to the accretion process. Observations of black hole X-ray binaries and the accretion environments near supermassive black holes provide mounting evidence for strong magnetization. Performing numerical simulations of accretion discs in the shearing box approximation, we impose a net vertical magnetic flux that allows us to effectively control the level of disc magnetization. We study how dynamo activity and the properties of turbulence driven by the magnetorotational instability depend on the

  9. Enclosed rotary disc air pulser

    DOEpatents

    Olson, A. L.; Batcheller, Tom A.; Rindfleisch, J. A.; Morgan, John M.

    1989-01-01

    An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.

  10. Heat distribution in disc brake

    NASA Astrophysics Data System (ADS)

    Klimenda, Frantisek; Soukup, Josef; Kampo, Jan

    2016-06-01

    This article is deals by the thermal analysis of the disc brake with floating caliper. The issue is solved by numerically. The half 2D model is used for solution in program ADINA 8.8. Two brake discs without the ventilation are solved. One disc is made from cast iron and the second is made from stainless steel. Both materials are an isotropic. By acting the pressure force on the brake pads will be pressing the pads to the brake disc. Speed will be reduced (slowing down). On the contact surface generates the heat, which the disc and pads heats. In the next part of article is comparison the maximum temperature at the time of braking. The temperatures of both materials for brake disc (gray cast iron, stainless steel) are compares. The heat flux during braking for the both materials is shown.

  11. Numbered nasal discs for waterfowl

    USGS Publications Warehouse

    Bartonek, J.C.; Dane, C.W.

    1964-01-01

    Numbered nasal discs were successfully used in studies requiring large numbers of individually marked waterfowl. The procedure for constructing these discs is outlined. Blue-winged teal (Anas discors) with 5/8-inch discs, and canvasback (Aythya valisineria) and redhead (A. americana) with 3/4-inch discs can be individually identified up to 50 and 80 yards, respectively, with a gunstock-mounted, 20-power spotting scope. The particular value of these markers is their durability, the number of combinations possible, and the apparent absence of behavioral or mortality influence among such species as the blue-winged teal.

  12. [Temporomandibular joint disc surgery].

    PubMed

    Potier, J; Maes, J-M; Nicot, R; Dumousseau, T; Cotelle, M; Ferri, J

    2016-09-01

    Temporomandibular joint (TMJ) disorders are a common disease and may be responsible for major functional and painful repercussions. Treatment is not consensual. The literature highlights the role of conservative treatments (physiotherapy, analgesics, splints) in a first attempt. Minimally invasive surgical techniques (arthroscopy, arthrocentesis) have developed rapidly in recent decades. They have proven effective and reliable, especially in patients suffering from irreducible or reducible anterior disc dislocation or presenting with arthopathies. The goal of our work was to make an update about disk surgery. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  13. Writing midwives' history: problems and pitfalls.

    PubMed

    Allotey, Janette C

    2011-04-01

    As more midwives are becoming interested in the history of midwifery and carrying out historical research, it is opportune to consider some of the problems and pitfalls of this approach. The study and writing of history initially involves the collection of evidence, followed by its critical analysis and interpretation. The scarcity and reliability of sources poses the first problem. Even with the greatest of insight, it is impossible to fully reconstruct the past and eliminate bias. Evidence is open to manipulation and distortion, affecting the way in which findings are presented to a readership. This paper, aimed at novice researchers in the field, focuses on some of the fundamental principles of good research, and contains examples of ways in which the past may be misinterpreted or changed. The nature and construction of professional knowledge will also be briefly examined to establish whether objectivity is possible within historical research.

  14. The EXIT procedure: principles, pitfalls, and progress.

    PubMed

    Marwan, Ahmad; Crombleholme, Timothy M

    2006-05-01

    Although performing procedures on a fetus before severing the umbilical cord has previously been reported, the principles of the ex utero intrapartum treatment (EXIT) procedure were first fully developed for reversing tracheal occlusion in fetuses with severe congenital diaphragmatic hernia. The EXIT procedure offers the advantage of insuring uteroplacental gas exchange while on placental support. The lessons learned in the development of the principles that underlie the EXIT procedure have improved outcomes when applied in other conditions, most notably in cases of airway obstruction. The range of indications for the EXIT procedure has expanded and currently includes giant fetal neck masses, lung or mediastinal tumors, congenital high airway obstruction syndrome, and EXIT to ECMO (extracorporeal membrane oxygenation), among others. This review summarizes the underlying principles of the EXIT procedure, the expanding indications for its use, the pitfalls of management, and the progress that has been made in its successful application.

  15. Potential Pitfalls in microRNA Profiling

    PubMed Central

    Chugh, Pauline; Dittmer, Dirk P.

    2013-01-01

    MicroRNAs (miRNAs) are small, noncoding RNAs that post-transcriptionally influence a wide range of cellular processes such as the host response to viral infection, innate immunity, cell cycle progression, migration and apoptosis through the inhibition of target mRNA translation. Due to the growing number of microRNAs and identification of their functional roles, miRNA profiling of many different sample types has become more expansive, especially with relevance to disease signatures. Here, we address some of the advantages and potential pitfalls of the currently available methods for miRNA expression profiling. Some of the topics discussed include isomiRNAs, comparison of different profiling platforms, normalization strategies and issues with regard to sample preparation and experimental analyses. PMID:22566380

  16. Recognizing the pitfalls of total quality management

    SciTech Connect

    Laza, R.W.; Wheaton, P.L.

    1990-04-12

    Should utilities be interested in total quality management (TQM) After all, the argument that better quality products should increase the sales and result in higher profits does not readily apply to a public utility operating in a monopolistic environment. Yet, utilities in the US are moving toward a more competitive environment; FPL's success with its TQM programs is forcing most utilities to look at TQM so as not to risk future competitive disadvantage. A few regulatory commissions have already started to inquire as to what steps utilities under their jurisdiction are taking to pursue the benefits of TQM. This article will address two facets of this issue. First, it will define what TQM is and identify the pitfalls that might keep a utility from attaining the full benefits of a well-executed TQM program. Second, it will lay out a simple, straightforward approach that a utility can use to determine whether and how to utilize this new management tool.

  17. Benchmarking with Spine Tango: potentials and pitfalls

    PubMed Central

    Staub, L.; Dietrich, D.; Zweig, T.; Melloh, M.; Aebi, M.

    2009-01-01

    The newly released online statistics function of Spine Tango allows comparison of own data against the aggregated results of the data pool that all other participants generate. This comparison can be considered a very simple way of benchmarking, which means that the quality of what one organization does is compared with other similar organizations. The goal is to make changes towards better practice if benchmarking shows inferior results compared with the pool. There are, however, pitfalls in this simplified way of comparing data that can result in confounding. This means that important influential factors can make results appear better or worse than they are in reality and these factors can only be identified and neutralized in a multiple regression analysis performed by a statistical expert. Comparing input variables, confounding is less of a problem than comparing outcome variables. Therefore, the potentials and limitations of automated online comparisons need to be considered when interpreting the results of the benchmarking procedure. PMID:19337759

  18. Pitfalls and variants in pediatric chest imaging.

    PubMed

    García Asensio, D; Fernández Martín, M

    2016-05-01

    Most pitfalls in the interpretation of pediatric chest imaging are closely related with the technique used and the characteristics of pediatric patients. To obtain a quality image that will enable the correct diagnosis, it is very important to use an appropriate technique. It is important to know how technical factors influence the image and to be aware of the possible artifacts that can result from poor patient cooperation. Moreover, radiologists need to be familiar with the normal anatomy in children, with the classic radiologic findings, and with the anatomic and developmental variants to avoid misinterpreting normal findings as pathological. Copyright © 2016 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

  19. 26 CFR 1.6011-2 - Returns, etc., of DISC's and former DISC's.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 13 2010-04-01 2010-04-01 false Returns, etc., of DISC's and former DISC's. 1... (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Tax Returns Or Statements § 1.6011-2 Returns, etc., of DISC's and former DISC's. (a) Records and information. Every DISC and former DISC (as defined in section 992...

  20. Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay

    USDA-ARS?s Scientific Manuscript database

    Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...

  1. Sizes of protoplanetary discs after star-disc encounters

    NASA Astrophysics Data System (ADS)

    Breslau, Andreas; Steinhausen, Manuel; Vincke, Kirsten; Pfalzner, Susanne

    2014-05-01

    Most stars do not form in isolation, but as part of a star cluster or association. These young stars are initially surrounded by protoplanetary discs. In these cluster environments tidal interactions with other cluster members can alter the disc properties. Besides the disc frequency, its mass, angular momentum, and energy, the disc's size is particularly prone to being changed by a passing star. So far the change in disc size has only been investigated for a small number of very specific encounters. Several studies investigated the effect of the cluster environment on the sizes of planetary systems like our own solar system, based on a generalisation of information from this limited sample. We performed numerical simulations covering the wide parameter space typical of young star clusters, to test the validity of this approach. Here the sizes of discs after encounters are presented, based on a size definition that is comparable to the one used in observational studies. We find that, except for encounters between equal-mass stars, the usually applied estimates are insufficient. They tend to severely overestimate the remaining disc size. We show that the disc size after an encounter can be described by a relatively simple dependence on the periastron distance and the mass ratio of the encounter partners. This knowledge allows us, for example, to pin down the types of encounter possibly responsible for the structure of today's solar system. Appendix A is available in electronic form at http://www.aanda.org

  2. The activL(®) Artificial Disc: a next-generation motion-preserving implant for chronic lumbar discogenic pain.

    PubMed

    Yue, James J; Garcia, Rolando; Miller, Larry E

    2016-01-01

    Degeneration of the lumbar intervertebral discs is a leading cause of chronic low back pain in adults. Treatment options for patients with chronic lumbar discogenic pain unresponsive to conservative management include total disc replacement (TDR) or lumbar fusion. Until recently, only two lumbar TDRs had been approved by the US Food and Drug Administration - the Charité Artificial Disc in 2004 and the ProDisc-L Total Disc Replacement in 2006. In June 2015, a next-generation lumbar TDR received Food and Drug Administration approval - the activL(®) Artificial Disc (Aesculap Implant Systems). Compared to previous-generation lumbar TDRs, the activL(®) Artificial Disc incorporates specific design enhancements that result in a more precise anatomical match and allow a range of motion that better mimics the healthy spine. The results of mechanical and clinical studies demonstrate that the activL(®) Artificial Disc results in improved mechanical and clinical outcomes versus earlier-generation artificial discs and compares favorably to lumbar fusion. The purpose of this report is to describe the activL(®) Artificial Disc including implant characteristics, intended use, surgical technique, postoperative care, mechanical testing, and clinical experience to date.

  3. The activL® Artificial Disc: a next-generation motion-preserving implant for chronic lumbar discogenic pain

    PubMed Central

    Yue, James J; Garcia, Rolando; Miller, Larry E

    2016-01-01

    Degeneration of the lumbar intervertebral discs is a leading cause of chronic low back pain in adults. Treatment options for patients with chronic lumbar discogenic pain unresponsive to conservative management include total disc replacement (TDR) or lumbar fusion. Until recently, only two lumbar TDRs had been approved by the US Food and Drug Administration − the Charité Artificial Disc in 2004 and the ProDisc-L Total Disc Replacement in 2006. In June 2015, a next-generation lumbar TDR received Food and Drug Administration approval − the activL® Artificial Disc (Aesculap Implant Systems). Compared to previous-generation lumbar TDRs, the activL® Artificial Disc incorporates specific design enhancements that result in a more precise anatomical match and allow a range of motion that better mimics the healthy spine. The results of mechanical and clinical studies demonstrate that the activL® Artificial Disc results in improved mechanical and clinical outcomes versus earlier-generation artificial discs and compares favorably to lumbar fusion. The purpose of this report is to describe the activL® Artificial Disc including implant characteristics, intended use, surgical technique, postoperative care, mechanical testing, and clinical experience to date. PMID:27274317

  4. Disc cell therapies: critical issues.

    PubMed

    Tibiletti, Marta; Kregar Velikonja, Nevenka; Urban, Jill P G; Fairbank, Jeremy C T

    2014-06-01

    Disc cell therapies, in which cells are injected into the degenerate disc in order to regenerate the matrix and restore function, appear to be an attractive, minimally invasive method of treatment. Interest in this area has stimulated research into disc cell biology in particular. However, other important issues, some of which are discussed here, need to be considered if cell-based therapies are to be brought to the clinic. Firstly, a question which is barely addressed in the literature, is how to identify patients with 'degenerative disc disease' who would benefit from cell therapy. Pain not disc degeneration is the symptom which drives patients to the clinic. Even though there are associations between back pain and disc degeneration, many people with even severely degenerate discs, with herniated discs or with spinal stenosis, are pain-free. It is not possible using currently available techniques to identify whether disc repair or regeneration would remove symptoms or prevent symptoms from occurring in future. Moreover, the repair process in human discs is very slow (years) because of the low cell density which can be supported nutritionally even in healthy human discs. If repair is necessary for relief of symptoms, questions regarding quality of life and rehabilitation during this long process need consideration. Also, some serious technical issues remain. Finding appropriate cell sources and scaffolds have received most attention, but these are not the only issues determining the feasibility of the procedure. There are questions regarding the safety of implanting cells by injection through the annulus whether the nutrient supply to the disc is sufficient to support implanted cells and whether, if cells are able to survive, conditions in a degenerate human disc will allow them to repair the damaged tissue. If cell therapy for treatment of disc-related disorders is to enter the clinic as a routine treatment, investigations must examine the questions related to

  5. Teaching Child Development Via the Internet: Opportunities and Pitfalls.

    ERIC Educational Resources Information Center

    Graham, Theresa A.

    2001-01-01

    Describes the development and implementation of a cross-listed undergraduate and graduate-level child psychology course taught over the Internet. Describes course content and instructional goals. Outlines the opportunities and pitfalls of teaching in a virtual classroom. (CMK)

  6. The Pleasures and the Pitfalls of Plant Science Activities.

    ERIC Educational Resources Information Center

    Hershey, David R.

    2000-01-01

    Classroom plant activities have long been inexpensive, easy to do, and fun for students, and have become more central to biology teaching. Introduces some plant science activities and their pleasures and pitfalls. (ASK)

  7. Fantastic Disc Activities for Fitness

    ERIC Educational Resources Information Center

    Griffin, Michael R.; Johnson, Romona; Thomas, Jessica; Spell, Melissa; Popham, John; Croft, Brent; Umpleby, Albert; Verbel, Eric

    2005-01-01

    Disc activities are an excellent elementary content area for both skill and fitness enhancement. They may occur through progressive skill and drill practice, small sided-game examples, modifications of traditional disc activities appropriate to large groups, and with adjustments designed to increase activity and fitness levels. For games in this…

  8. Androgens and doping tests: genetic variation and pit-falls

    PubMed Central

    Rane, Anders; Ekström, Lena

    2012-01-01

    The large variation in disposition known for most drugs is also true for anabolic androgenic steroids. Genetic factors are probably the single most important cause of this variation. Further, there are reasons to believe that there is a corresponding variation in efficacy of doping agents. Doped individuals employ a large variety of doping strategies in respect of choice of substance, dose, dose interval, duration of treatment and use of other drugs for enforcement of effects or correction of side effects. Metabolic steps up-stream and down-stream of testosterone are genetically variable and contribute substantially to the variation in disposition of testosterone, the most common doping agent in sports and in society. Large inter- and intra-ethnic variation in testosterone glucuronidation and excretion is described as well as the pit-falls in evaluation of testosterone doping test results. The hydrolysis and bioactivation of testosterone enanthate is also genetically variable yielding a 2–3 fold variation in excretion rate and serum concentration, thereby implicating a substantial variation in ‘efficacy’ of testosterone. Given this situation it is logical to adopt the new findings in the doping control programme. The population based cut-off level for the testosterone : epitestosterone ratio should be replaced by a Bayesian interpretation of consecutive tests in the same individual. When combined with the above genetic information the sensitivity of the test is considerably improved. The combination of the three approaches should reduce the rate of falsely negative or positive results and the number of expensive follow-up tests, stipulated by the World Anti-Doping Agency. PMID:22506612

  9. Radiofrequency stimulation of intervertebral discs.

    PubMed

    Rosen, Steven; Falco, Frank

    2003-10-01

    The etiology of discogenic pain is poorly understood. The most accepted theory has been that nociceptors in the outer one-third of the annulus fibrosis are responsible for transmitting pain secondary to internal disc disruptions. The concept of "neoneuralization" after disc injury has been disseminated. It has been noted that disc degeneration and injury are associated with ingrowth of neural fibers into the disc annulus. One mechanism of Intradiscal Electrodothermal Therapy (IDET) has been thought to be lesioning of these nociceptors. Five consecutive patients were studied using an intraannular electrode. The Radionics discTRODE was used. It was found impossible to selectively stimulate axial pain fibers using this system. Radicular stimulation was noted in all patients at all levels studied. The implication of these findings concerning the concept of neoneuralization, mechanism of IDET, and possible strategies to decrease discogenic pain are discussed.

  10. Imaginal disc regeneration takes flight.

    PubMed

    Hariharan, Iswar K; Serras, Florenci

    2017-04-01

    Drosophila imaginal discs, the larval precursors of adult structures such as the wing and leg, are capable of regenerating after damage. During the course of regeneration, discs can sometimes generate structures that are appropriate for a different type of disc, a phenomenon termed transdetermination. Until recently, these phenomena were studied by physically fragmenting discs and then transplanting them into the abdomens of adult female flies. This field has experienced a renaissance following the development of genetic ablation systems that can damage precisely defined regions of the disc without the need for surgery. Together with more traditional approaches, these newer methods have generated many novel insights into wound healing, the mechanisms that drive regenerative growth, plasticity during regeneration and systemic effects of tissue damage and regeneration.

  11. Intraoral micro-identification discs.

    PubMed

    Hansen, R W

    1991-12-01

    Intraoral micro-identification discs have recently been utilized to provide a more permanent method of personal identification. A wafer of plastic or metal with a surface area of 2.5 to 5 mm2 and carrying identifying numbers and/or letters (indicia) is bonded to the buccal enamel surface of the posterior teeth. Personal identification can occur after the I.D. disc is identified and the indicia is read. Reading of photoreduced indicia requires the aid of a microscope subsequent to the removal of the microdisc. In situ reading of disc indicia is possible using low power handheld magnifiers if the size of the indicia approximates 0.3 mm. Computerization is an integral part of non-custom alpha/numeric type designs, but a custom disc carries a name, address, and other specific information unique to the manufacturer. The use of a computer improves access to the database and it decreases the amount of data placed on the disc. Microdisc bases may be fabricated using a mylar type plastic or they may be manufactured from a stainless steel blank. Plastic discs are constructed with an internal sandwich containing the photo-reduced indicia. Metal discs are marked with a photochemical etch or engraved with a computer driven YAG laser. Attachment of the disc to the enamel surface is accomplished by conventional etching and bonding techniques and are typically bonded to the buccal surface of the maxillary first permanent molar or the second primary molar. Clear composite bonding material covers the disc so that salivary contamination does not result in degradation of the indicia. Orthodontic style discs with a mesh back carry laser written information that may be cemented with conventional orthodontic bonding cement. Standardization of the indicia and overall design is considered to be an important aspect of patient and professional acceptance.

  12. Cervical Total Disc Arthroplasty

    PubMed Central

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer. PMID:24353955

  13. Development and Translation of a Tissue- Engineered Disc in a Preclinical Rodent Model

    DTIC Science & Technology

    2011-10-01

    exposure for stem cells cultured in an engineered nucleus pulposus-like hyaluronan hydrogel. We have developed and validated a minimally invasive...a hyaluronic acid hydrogel seeded with adult stem cells that can be used to replace the degenerate native disc. Proposed Aim 1: Create a...mesenchymal stem cell (MSC) seeded 3D structural TEC disc from concentric AF constructs surrounding an engineered nucleus pulposus (NP) composed of a

  14. Promises and pitfalls of quantitative structure-activity relationship approaches for predicting metabolism and toxicity.

    PubMed

    Zvinavashe, Elton; Murk, Albertinka J; Rietjens, Ivonne M C M

    2008-12-01

    The description of quantitative structure-activity relationship (QSAR) models has been a topic for scientific research for more than 40 years and a topic within the regulatory framework for more than 20 years. At present, efforts on QSAR development are increasing because of their promise for supporting reduction, refinement, and/or replacement of animal toxicity experiments. However, their acceptance in risk assessment seems to require a more standardized and scientific underpinning of QSAR technology to avoid possible pitfalls. For this reason, guidelines for QSAR model development recently proposed by the Organization for Economic Cooperation and Development (OECD) [Organization for Economic Cooperation and Development (OECD) (2007) Guidance document on the validation of (quantitative) structure-activity relationships [(Q)SAR] models. OECD Environment Health and Safety Publications: Series on Testing and Assessment No. 69, Paris] are expected to help increase the acceptability of QSAR models for regulatory purposes. The guidelines recommend that QSAR models should be associated with (i) a defined end point, (ii) an unambiguous algorithm, (iii) a defined domain of applicability, (iv) appropriate measures of goodness-of-fit, robustness, and predictivity, and (v) a mechanistic interpretation, if possible [Organization for Economic Cooperation and Development (OECD) (2007) Guidance document on the validation of (quantitative) structure-activity relationships [(Q)SAR] models. The present perspective provides an overview of these guidelines for QSAR model development and their rationale, as well as the promises and pitfalls of using QSAR approaches and these guidelines for predicting metabolism and toxicity of new and existing chemicals.

  15. Double-disc gate valve

    DOEpatents

    Wheatley, Seth J.

    1979-01-01

    This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

  16. Comparison of animal discs used in disc research to human lumbar disc: torsion mechanics and collagen content.

    PubMed

    Showalter, Brent L; Beckstein, Jesse C; Martin, John T; Beattie, Elizabeth E; Espinoza Orías, Alejandro A; Schaer, Thomas P; Vresilovic, Edward J; Elliott, Dawn M

    2012-07-01

    Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these with the human disc. To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar discs, and cow, rat, and mouse caudal discs. Collagen content was measured and normalized by dry weight for the same discs except the rat and the mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human discs. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Disc torsion mechanics are comparable with human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented are useful for selecting and interpreting results for animal disc models. Structural organization of the fiber angle may explain the differences that were noted between species after geometric normalization.

  17. Mitral disc-valve variance

    PubMed Central

    Berroya, Renato B.; Escano, Fernando B.

    1972-01-01

    This report deals with a rare complication of disc-valve prosthesis in the mitral area. A significant disc poppet and struts destruction of mitral Beall valve prostheses occurred 20 and 17 months after implantation. The resulting valve incompetence in the first case contributed to the death of the patient. The durability of Teflon prosthetic valves appears to be in question and this type of valve probably will be unacceptable if there is an increasing number of disc-valve variance in the future. Images PMID:5017573

  18. Medical Information on Optical Disc*

    PubMed Central

    Schipma, Peter B.; Cichocki, Edward M.; Ziemer, Susan M.

    1987-01-01

    Optical discs may permit a revolutionary change in the distribution and use of medical information. A single compact disc, similar in size to that used for digital audio recording, can contain over 500 million characters of information that is accessible by a Personal Computer. These discs can be manufactured at a cost lower than that of print on paper, at reasonable volumes. Software can provide the health care professional with nearly instantaneous access to the information. Thus, for the first time, the opportunity exists to have large local medical information collections. This paper describes an application of this technology in the field of Oncology.

  19. Avoiding numerical pitfalls in social force models

    NASA Astrophysics Data System (ADS)

    Köster, Gerta; Treml, Franz; Gödel, Marion

    2013-06-01

    The social force model of Helbing and Molnár is one of the best known approaches to simulate pedestrian motion, a collective phenomenon with nonlinear dynamics. It is based on the idea that the Newtonian laws of motion mostly carry over to pedestrian motion so that human trajectories can be computed by solving a set of ordinary differential equations for velocity and acceleration. The beauty and simplicity of this ansatz are strong reasons for its wide spread. However, the numerical implementation is not without pitfalls. Oscillations, collisions, and instabilities occur even for very small step sizes. Classic solution ideas from molecular dynamics do not apply to the problem because the system is not Hamiltonian despite its source of inspiration. Looking at the model through the eyes of a mathematician, however, we realize that the right hand side of the differential equation is nondifferentiable and even discontinuous at critical locations. This produces undesirable behavior in the exact solution and, at best, severe loss of accuracy in efficient numerical schemes even in short range simulations. We suggest a very simple mollified version of the social force model that conserves the desired dynamic properties of the original many-body system but elegantly and cost efficiently resolves several of the issues concerning stability and numerical resolution.

  20. Avoiding legal pitfalls in surrogacy arrangements.

    PubMed

    James, Summer; Chilvers, Rebecca; Havemann, Dara; Phelps, John Y

    2010-12-01

    The goal of this article is to discuss the legal pitfalls that reproductive endocrinologists face when participating in gestational surrogacy contracts. This paper was composed using Westlaw and LexisNexis commercial legal search engines to perform a review of statutes and cases pertaining to gestational surrogacy. The search results demonstrated that in the absence of suitable preparation, there is significant potential for litigation while participating in gestational agreements. Providers caring for gestational carriers have been named as parties in lawsuits for failure to provide psychological screening, failure to screen for infectious disease and participation in gestational contracts that are not compliant with state law. There is great disparity in state laws and court rulings pertaining to gestational agreements. When legal disputes arise, individual state laws and court rulings are controlling over the Uniform Parentage Act. Likewise, recommendations by the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine do not supersede state laws. The failure to abide by individual state laws unnecessarily exposes reproductive endocrinologists and their IVF facilities to potential litigation. In order to lessen exposure to litigation, an understanding of individual state legislation or historical court rulings is advised. Copyright © 2010 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  1. Esophageal Impedance Monitoring: Clinical Pearls and Pitfalls.

    PubMed

    Ravi, Karthik; Katzka, David A

    2016-09-01

    The development of intraluminal esophageal impedance monitoring has improved our ability to detect and measure gastroesophageal reflux without dependence on acid content. This ability to detect previously unrecognized weak or nonacid reflux episodes has had important clinical implications in the diagnosis and management of gastroesophageal reflux disease (GERD). In addition, with the ability to assess bolus transit within the esophageal lumen, impedance monitoring has enhanced the recognition and characterization of esophageal motility disorders in patients with nonobstructive dysphagia. The assessment of the intraluminal movement of gas and liquid has also been proven to be of diagnostic value in conditions such as rumination syndrome and excessive belching. Further, alternative applications of impedance monitoring, such as the measurement of mucosal impedance, have provided novel insights into assessing esophageal mucosal integrity changes as a consequence of inflammatory change. Future applications for esophageal impedance monitoring also hold promise in esophageal conditions other than GERD. However, despite all of the clinical benefits afforded by esophageal impedance monitoring, important clinical and technical shortcomings limit its diagnostic value and must be considered when interpreting study results. Overinterpretation of studies or application of impedance monitoring in patients can have deleterious clinical implications. This review will highlight the clinical benefits and limitations of esophageal impedance monitoring and provide clinical pearls and pitfalls associated with this technology.

  2. Operative Management of Lumbar Degenerative Disc Disease.

    PubMed

    Lee, Yu Chao; Zotti, Mario Giuseppe Tedesco; Osti, Orso Lorenzo

    2016-08-01

    Lumbar degenerative disc disease is extremely common. Current evidence supports surgery in carefully selected patients who have failed non-operative treatment and do not exhibit any substantial psychosocial overlay. Fusion surgery employing the correct grafting and stabilization techniques has long-term results demonstrating successful clinical outcomes. However, the best approach for fusion remains debatable. There is some evidence supporting the more complex, technically demanding and higher risk interbody fusion techniques for the younger, active patients or patients with a higher risk of non-union. Lumbar disc arthroplasty and hybrid techniques are still relatively novel procedures despite promising short-term and mid-term outcomes. Long-term studies demonstrating superiority over fusion are required before these techniques may be recommended to replace fusion as the gold standard. Novel stem cell approaches combined with tissue engineering therapies continue to be developed in expectation of improving clinical outcomes. Results with appropriate follow-up are not yet available to indicate if such techniques are safe, cost-effective and reliable in the long-term.

  3. Operative Management of Lumbar Degenerative Disc Disease

    PubMed Central

    Lee, Yu Chao; Osti, Orso Lorenzo

    2016-01-01

    Lumbar degenerative disc disease is extremely common. Current evidence supports surgery in carefully selected patients who have failed non-operative treatment and do not exhibit any substantial psychosocial overlay. Fusion surgery employing the correct grafting and stabilization techniques has long-term results demonstrating successful clinical outcomes. However, the best approach for fusion remains debatable. There is some evidence supporting the more complex, technically demanding and higher risk interbody fusion techniques for the younger, active patients or patients with a higher risk of non-union. Lumbar disc arthroplasty and hybrid techniques are still relatively novel procedures despite promising short-term and mid-term outcomes. Long-term studies demonstrating superiority over fusion are required before these techniques may be recommended to replace fusion as the gold standard. Novel stem cell approaches combined with tissue engineering therapies continue to be developed in expectation of improving clinical outcomes. Results with appropriate follow-up are not yet available to indicate if such techniques are safe, cost-effective and reliable in the long-term. PMID:27559465

  4. Decellularized allogeneic intervertebral disc: natural biomaterials for regenerating disc degeneration

    PubMed Central

    Hu, Zhijun; Chen, Kai; Shan, Zhi; Chen, Shuai; Wang, Jiying; Mo, Jian; Ma, Jianjun; Xu, Wenbing; Qin, An; Fan, Shunwu

    2016-01-01

    Intervertebral disc degeneration is associated with back pain and disc herniation. This study established a modified protocol for intervertebral disc (IVD) decellularization and prepared its extracellular matrix (ECM). By culturing mesenchymal stem cells (MSCs)(3, 7, 14 and 21 days) and human degenerative IVD cells (7 days) in the ECM, implanting it subcutaneously in rabbit and injecting ECM microparticles into degenerative disc, the biological safety and efficacy of decellularized IVD was evaluated both in vitro and in vivo. Here, we demonstrated that cellular components can be removed completely after decellularization and maximally retain the structure and biomechanics of native IVD. We revealed that allogeneic ECM did not evoke any apparent inflammatory reaction in vivo and no cytotoxicity was found in vitro. Moreover, IVD ECM can induce differentiation of MSCs into IVD-like cells in vitro. Furthermore, allogeneic ECM microparticles are effective on the treatment of rabbit disc degeneration in vivo. In conclusion, our study developed an optimized method for IVD decellularization and we proved decellularized IVD is safe and effective for the treatment of degenerated disc diseases. PMID:26933821

  5. Enlivening Physics, a Local Video Disc Project.

    ERIC Educational Resources Information Center

    McInerney, M.

    1989-01-01

    Describes how to make and use an inexpensive video disc of physics demonstrations. Discusses the background, production of the disc, subject of the disc including angular momentum, "monkey and the hunter" experiment, Doppler shift, pressure of a constant volume of gas thermometer, and wave effects, and using the disc in classroom. (YP)

  6. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD... SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank, the rupture disc must— (a) Rupture at a pressure of...

  7. Disc Golf: Teaching a Lifetime Activity

    ERIC Educational Resources Information Center

    Eastham, Susan L.

    2015-01-01

    Disc golf is a lifetime activity that can be enjoyed by students of varying skill levels and abilities. Disc golf follows the principles of ball golf but is generally easier for students to play and enjoy success. The object of disc golf is similar to ball golf and involves throwing a disc from the teeing area to the target in as few throws as…

  8. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD... SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank, the rupture disc must— (a) Rupture at a pressure of...

  9. Disc Golf: Teaching a Lifetime Activity

    ERIC Educational Resources Information Center

    Eastham, Susan L.

    2015-01-01

    Disc golf is a lifetime activity that can be enjoyed by students of varying skill levels and abilities. Disc golf follows the principles of ball golf but is generally easier for students to play and enjoy success. The object of disc golf is similar to ball golf and involves throwing a disc from the teeing area to the target in as few throws as…

  10. Design Issues in Video Disc Map Display.

    DTIC Science & Technology

    1984-10-01

    Tables: disc storage capacities under various conditions. Photos: map frames. Constanzo , D.J. (1984a), "The Potential for Video Disc Technology in...discs. Constanzo , D.J. (1984b), "Requirements and Specifications for Cartographic Video Discs", presented as a poster paper at the 1984 Army Science

  11. Enlivening Physics, a Local Video Disc Project.

    ERIC Educational Resources Information Center

    McInerney, M.

    1989-01-01

    Describes how to make and use an inexpensive video disc of physics demonstrations. Discusses the background, production of the disc, subject of the disc including angular momentum, "monkey and the hunter" experiment, Doppler shift, pressure of a constant volume of gas thermometer, and wave effects, and using the disc in classroom. (YP)

  12. 26 CFR 1.246-4 - Dividends from a DISC or former DISC.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 3 2011-04-01 2011-04-01 false Dividends from a DISC or former DISC. 1.246-4... a DISC or former DISC. The deduction provided in section 243 (relating to dividends received by... distribution or an amount treated as a dividend pursuant to section 995(c)) from a corporation which is a DISC...

  13. Tissue engineering: A live disc

    NASA Astrophysics Data System (ADS)

    Hukins, David W. L.

    2005-12-01

    A material-cell hybrid device that mimics the anatomic shape of the intervertebral disc has been made and successfully implanted into mice to show that tissue engineering may, in the future, benefit sufferers from back pain.

  14. Eclipse Mapping of Accretion Discs

    NASA Astrophysics Data System (ADS)

    Baptista, R.

    The eclipse mapping method is an inversion technique that makes use of the information contained in eclipse light curves to probe the structure, the spectrum and the time evolution of accretion discs. In this review I present the basics of the method and discuss its different implementations. I summarize the most important results obtained to date and discuss how they have helped to improve our understanding of accretion physics, from testing the theoretical radial brightness temperature distribution and measuring mass accretion rates to showing the evolution of the structure of a dwarf novae disc throughout its outburst cycle, from isolating the spectrum of a disc wind to revealing the geometry of disc spiral shocks. I end with an outline of the future prospects.

  15. Disc Golf, a Growing Sport

    PubMed Central

    Nelson, Joseph T.; Jones, Richard E.; Runstrom, Michael; Hardy, Jolene

    2015-01-01

    Background Disc golf is a sport played much like traditional golf, but rather than using a ball and club, players throw flying discs with various throwing motions. It has been played by an estimated 8 to 12 million people in the United States. Like all sports, injuries sustained while playing disc golf are not uncommon. Although formalized in the 1970s, it has grown at a rapid pace; however, disc golf–related injuries have yet to be described in the medical literature. Purpose To describe the most common injuries incurred by disc golf players while comparing the different types of throwing styles. Study Design Descriptive epidemiology study. Methods The data in this study were collected from 883 disc golf players who responded to an online survey collected over a 1-month period. Respondents answered 49 questions related to demographics, experience, style of play, and injury details. Using a chi-square analysis, common injuries sustained in players using backhand and forehand throwing styles were compared. Results More than 81% of respondents stated that they had sustained an injury playing disc golf, including injuries to the elbow (n = 325), shoulder (n = 305), back (n = 218), and knee (n = 199). The injuries were most commonly described as a muscle strain (n = 241), sprain (n = 162), and tendinitis (n = 145). The type of throw primarily used by players varied, with 86.2% using backhand, 12.7% using forehand, and 1.1% using an overhead throw. Players using a forehand throw were more likely to sustain an elbow injury (P = .014). Many players (n = 115) stated they had undergone surgery due to a disc golf–related injury, with the most common surgeries including meniscal, shoulder, spine, and foot/ankle surgeries. Conclusion The majority of surveyed disc golfers sustained at least 1 injury while playing disc golf, with many requiring surgery. The types of injuries sustained by players varied by the types of throw primarily used. As the sport of disc golf continues

  16. Analysis of the Function of Apoptosis during Imaginal Wing Disc Regeneration in Drosophila melanogaster.

    PubMed

    Diaz-Garcia, Sandra; Ahmed, Sara; Baonza, Antonio

    2016-01-01

    Regeneration is the ability that allows organisms to replace missing organs or lost tissue after injuries. This ability requires the coordinated activity of different cellular processes, including programmed cell death. Apoptosis plays a key role as a source of signals necessary for regeneration in different organisms. The imaginal discs of Drosophila melanogaster provide a particularly well-characterised model system for studying the cellular and molecular mechanisms underlying regeneration. Although it has been shown that signals produced by apoptotic cells are needed for homeostasis and regeneration of some tissues of this organism, such as the adult midgut, the contribution of apoptosis to disc regeneration remains unclear. Using a new method for studying disc regeneration in physiological conditions, we have defined the pattern of cell death in regenerating discs. Our data indicate that during disc regeneration, cell death increases first at the wound edge, but as regeneration progresses dead cells can be observed in regions far away from the site of damage. This result indicates that apoptotic signals initiated in the wound spread throughout the disc. We also present results which suggest that the partial inhibition of apoptosis does not have a major effect on disc regeneration. Finally, our results suggest that during disc regeneration distinct apoptotic signals might be acting simultaneously.

  17. Sensitivity of notochordal disc cells to mechanical loading: an experimental animal study.

    PubMed

    Guehring, Thorsten; Nerlich, Andreas; Kroeber, Markus; Richter, Wiltrud; Omlor, Georg W

    2010-01-01

    The immature disc nucleus pulposus (NP) consists of notochordal cells (NCs). With maturation NCs disappear in humans, to be replaced by chondrocyte-like mature NP cells (MNPCs); this change in cell phenotype coincidences with early signs of disc degeneration. The reasons for NC disappearance are important to understand disc degeneration, but remain unknown, yet. This study investigated, whether loading induced a change from a notochordal nucleus phenotype to a chondrocyte-like one. An in vivo disc compression model with fixateur externe was used in 36 mature rabbits. Discs were compressed for different time periods (1, 28, 56 days), and compared with uncompressed control discs (56 days without treatment), and discs with sham compression (28 days). Nucleus cell phenotype was determined by histology and immunohistochemistry. NCs, but not MNPCs highly expressed bone-morphogenetic-protein 2 and cytokeratin 8, thus NC and MNPC numbers could be determined. A histologic score was used to detect structural endplate changes after compression (28 days). Control and sham compressed discs contained around 70% NCs and 30% MNPCs, to be decreased to <10% NCs after 28-56 days of loading. NC density fell sharply by >50% after 28-56 days of compression (P < 0.05 vs. controls). Signs of decreased endplate cellularity and increased endplate sclerosis and fibrosis were found after loading. These experiments show that NCs were less resistant to mechanical stress than MNPCs suggesting that increased intradiscal pressures after loading, and limited nutrition through structurally altered endplates could instigate the disappearance of NCs.

  18. Percutaneous diode laser disc nucleoplasty

    NASA Astrophysics Data System (ADS)

    Menchetti, P. P.; Longo, Leonardo

    2004-09-01

    The treatment of herniated disc disease (HNP) over the years involved different miniinvasive surgical options. The classical microsurgical approach has been substituted over the years both by endoscopic approach in which is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc nucleoplasty. In the last ten years, the percutaneous laser disc nucleoplasty have been done worldwide in more than 40000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by the disc protrusion pressing against the nerve root, a 980 nm Diode laser introduced via a 22G needle under X-ray guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Material and method: to date, 130 patients (155 cases) suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Eightyfour (72%) males and 46 (28%) females had a percutaneous laser disc nucleoplasty. The average age of patients operated was 48 years (22 - 69). The level of disc removal was L3/L4 in 12 cases, L4/L5 in 87 cases and L5/S1 in 56 cases. Two different levels were treated at the same time in 25 patients. Results: the success rate at a minimum follow-up of 6 months was 88% with a complication rate of 0.5%.

  19. Comparison of Animal Discs Used in Disc Research to Human Lumbar Disc: Torsion Mechanics and Collagen Content

    PubMed Central

    Showalter, Brent L.; Beckstein, Jesse C.; Martin, John T.; Beattie, Elizabeth E.; Orías, Alejandro A. Espinoza; Schaer, Thomas P.; Vresilovic, Edward J.; Elliott, Dawn M.

    2012-01-01

    Study Design Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these to the human disc. Objective To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. Summary of Background Data There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Methods Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar, and cow, rat, and mouse caudal. Collagen content was measured and normalized by dry weight for the same discs except the rat and mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Results Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Conclusion Disc torsion mechanics are comparable to human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented is useful for selecting and interpreting results for animal models of the disc. Structural composition of the disc, such as initial fiber angle, may explain the differences that were noted between species after geometric normalization. PMID:22333953

  20. An Analysis of Burst Disc Pressure Instability

    SciTech Connect

    S. L. Robinson; B. C. Odegard, Jr.; N. r. Moody; S. H. Goods

    2000-06-01

    During the development stage of the 1X Acorn burst disc, burst pressure test results exhibited an unexpected increase of 8 to 14% over times of 90--100 days from initial fabrication. This increase is a concern where design constraints require stability. The disc material, 316L stainless steel sheet, is formed to a dome-like geometry and scored to produce a thin-walled, high-strength ligament. The fracture events controlling burst occur in that ligament. Thus it has been characterized both for tensile properties and microstructure through nanoindentation, magnetic measurements, optical and transmission electron microscopy. These results compare favorably with finite element simulation of the properties of the ligament. The ligament exhibits a highly heterogeneous microstructure; its small volume and microstructural heterogeneity make it difficult to identify which microstructural feature controls fracture and hence burst pressure. Bulk mechanical test specimens were fabricated to emulate mid-ligament properties, and aged at both room and elevated temperatures to characterize and accelerate the temporal behavior of the burst disc. Property changes included yield and ultimate tensile strength increases, and fracture strain decreases with aging. Specimens were subjected to a reversion anneal identical to that given the burst disc to eliminate the martensite phase formed during rolling. Reversion-annealed samples exhibited no change in properties in room temperature or accelerated aging, showing that the reversion-anneal eliminated the aging phenomenon. Aging was analyzed in terms of diffusion controlled precipitate growth kinetics, showing that carbon migration to dislocations is consistent with the strength increases. A vacancy-assisted diffusion mechanism for carbon transport is proposed, giving rise to rapid aging, which replaces interstitial carbon diffusion until excess vacancies from deformation are consumed. Mechanical activation parameters in stress relaxation

  1. Evolution of protoplanetary discs with magnetically driven disc winds

    NASA Astrophysics Data System (ADS)

    Suzuki, Takeru K.; Ogihara, Masahiro; Morbidelli, Alessandro; Crida, Aurélien; Guillot, Tristan

    2016-12-01

    Aims: We investigate the evolution of protoplanetary discs (PPDs) with magnetically driven disc winds and viscous heating. Methods: We considered an initially massive disc with 0.1 M⊙ to track the evolution from the early stage of PPDs. We solved the time evolution of surface density and temperature by taking into account viscous heating and the loss of mass and angular momentum by the disc winds within the framework of a standard α model for accretion discs. Our model parameters, turbulent viscosity, disc wind mass-loss, and disc wind torque, which were adopted from local magnetohydrodynamical simulations and constrained by the global energetics of the gravitational accretion, largely depends on the physical condition of PPDs, particularly on the evolution of the vertical magnetic flux in weakly ionized PPDs. Results: Although there are still uncertainties concerning the evolution of the vertical magnetic flux that remains, the surface densities show a large variety, depending on the combination of these three parameters, some of which are very different from the surface density expected from the standard accretion. When a PPD is in a wind-driven accretion state with the preserved vertical magnetic field, the radial dependence of the surface density can be positive in the inner region <1-10 au. The mass accretion rates are consistent with observations, even in the very low level of magnetohydrodynamical turbulence. Such a positive radial slope of the surface density strongly affects planet formation because it inhibits the inward drift or even causes the outward drift of pebble- to boulder-sized solid bodies, and it also slows down or even reversed the inward type-I migration of protoplanets. Conclusions: The variety of our calculated PPDs should yield a wide variety of exoplanet systems.

  2. Pitfalls of femoral titanium elastic nailing.

    PubMed

    Salonen, A; Lahdes-Vasama, T; Mattila, V M; Välipakka, J; Pajulo, O

    2015-06-01

    Despite several potential complications of elastic intramedullary nailing, it is currently the treatment of choice for femoral diaphyseal fractures in school-aged children. This study aimed to critically evaluate the complications of titanium elastic nailing in pediatric femoral shaft fractures. This study evaluated patients with a diaphyseal femoral fracture treated with titanium elastic nailing (TEN) in Tampere University Hospital in Finland. The study group included 32 children with a mean age of 9 years during a 5-year period, from 1 January 2003 to 31 December 2007. Data were collected from medical records and x-rays. Mean follow-up time was 42 months. Of 32 patients, 9 (28%) reported a postoperative complication. Complications were associated with nail prominence in five (16%) patients and instability in four (12%) patients. In patients with nail prominence, the titanium elastic nailing-nail ends were unbent and 10-35 mm outside the cortex of the distal femur. The nail prominence caused pain and delayed knee mobilization until the nail was removed after a mean time of 4 months. In patients with fracture instability, the mean titanium elastic nailing-nail/medullary canal diameter ratio was 46% and periosteal callus formation was 5.4 mm at the first control. In those with stable fractures, the values were 66% and 9.2 mm, respectively. Based on this study, two types of pitfalls in a small volume center were found. Titanium elastic nail ends were left unbent and too long. We recommend palpating the nail ends to exclude nail prominence and to verify free movement of the knee after nail cutting and bending. Fracture instability was caused by inserting titanium elastic nailing-nails that were too narrow. To avoid this complication, careful preoperative planning to select the proper-size titanium elastic nailing-nails and intraoperative testing of fracture stability under continuous fluoroscopy after the operation is advised. © The Finnish Surgical Society 2014.

  3. Avoiding pitfalls when implementing local area networks in hospital environments.

    PubMed

    Kaudewitz, G; Schulte, A

    1995-01-01

    This paper is intended to outline some of the most commonly encountered, but yet still underestimated pitfalls during the implementation of computer systems networks in hospitals and health care institutions and to give information technology planners and responsibles some practical hints for avoiding them. Pitfalls encountered during the difficult process of achieving consensus among all groups concerned on the necessity for electronic data processing in health care institutions will not be addressed here [1], though the authors believe that some major risks for project failure stem from shortcomings in this field. Instead, those pitfalls encountered during project initialization and project realization with the phases of analysis, design, contracting, installation, and maintenance will be discussed. The paper concludes with the authors' opinion that only the application of industry-proven project management and realization techniques will allow health care administrators to cope with the steadily increasing risks for failure of information technology projects in health care.

  4. Straight-line drift fences and pitfall traps

    USGS Publications Warehouse

    Corn, Paul Stephen

    1994-01-01

    Straight-line drift fences typically are short barriers (5-15 m) that direct animals traveling on the substrate surface into traps places at the ends of or beside the barriers. Traps (described below) can be pitfalls, funnel traps, or a combination of the two. Drift fences with pitfall or funnel traps and pitfall traps without fences are used commonly to inventory and monitor populations of amphibians and reptiles. For example, 9 of 17 field studies reported for management of terrestrial vertebrates (Sarzo et al. 1988) used these techniques to sample amphibians. Drift fences with pitfall traps can be used to determine species richness at a site and to detect the presence of rare species. They also can yield data on relative abundances and habitat use of selected species. Pitfall traps arrayed in a grid without fences can also be used to study the population ecology and habitat use of selected species. Population density can be estimated with this latter technique if used in conjunction with mark-recapture techniques (see Chapter 8). Drift fence arrays or pitfall grids can be left in place for long-term monitoring. In this section, I discuss the use of this technique to obtain data on amphibians away from breeding ponds. Use of drift fences and traps to monitory amphibian activity at breeding ponds is discussed in the section "Drift Fences Encircling Breeding Sits", below (technique 9). Some materials and procedures are common to both techniques. Investigators contemplating the use of drift fences and traps in any context should read both accounts.

  5. Polarimetric Models of Circumstellar Discs Including Aggregate Dust Grains

    NASA Astrophysics Data System (ADS)

    Mohan, Mahesh

    The work conducted in this thesis examines the nature of circumstellar discs by investigating irradiance and polarization of scattered light. Two circumstellar discs are investigated. Firstly, H-band high contrast imaging data on the transitional disc of the Herbig Ae/Be star HD169142 are presented. The images were obtained through the polarimetric differential imaging (PDI) technique on the Very Large Telescope (VLT) using the adaptive optics system NACO. Our observations use longer exposure times, allowing us to examine the edges of the disc. Analysis of the observations shows distinct signs of polarization due to circumstellar material, but due to excessive saturation and adaptive optics errors further information on the disc could not be inferred. The HD169142 disc is then modelled using the 3D radiative transfer code Hyperion. Initial models were constructed using a two disc structure, however recent PDI has shown the existence of an annular gap. In addition to this the annular gap is found not to be devoid of dust. This then led to the construction of a four-component disc structure. Estimates of the mass of dust in the gap (2.10E-6 Msun) are made as well as for the planet (1.53E-5 Msun (0.016 Mjupiter)) suspected to be responsible for causing the gap. The predicted polarization was also estimated for the disc, peaking at ~14 percent. The use of realistic dust grains (ballistic aggregate particles) in Monte Carlo code is also examined. The fortran code DDSCAT is used to calculate the scattering properties for aggregates which are used to replace the spherical grain models used by the radiative transfer code Hyperion. Currently, Hyperion uses four independent elements to define the scattering matrix, therefore the use of rotational averaging and a 50/50 percent population of grains and their enantiomers were explored to reduce the number of contributing scattering elements from DDSCAT. A python script was created to extract the scattering data from the DDSCAT

  6. Pitfalls and Limitations of Radionuclide Renal Imaging in Pediatrics.

    PubMed

    Biassoni, Lorenzo

    2015-09-01

    The article presents common pitfalls encountered in pediatric radionuclide renography, illustrated with clinical cases. It is important to recognize normal variants. A good acquisition technique is essential. Correlation with other imaging techniques, with the clinical background and symptoms, is critical. A clear clinical question is essential: based on the question and knowing the strengths and weaknesses of each test, the test which can best answer the question can be selected. Awareness of the pitfalls of radionuclide renography helps avoid errors of interpretation and allows the selection of the most helpful test for clinical management.

  7. Distance education at university level - opportunities and pitfalls

    NASA Astrophysics Data System (ADS)

    Jones, B. W.

    2006-08-01

    Distance education is making an increasing contribution at university level in developed and developing countries. Like all forms of education there is the good, the bad, and the ugly. In this talk I will present what is widely regarded as good practice in distance education, and underline the pitfalls that will lead to poor learning. Developing countries are particularly prone to certain pitfalls. I will address four areas. 1 The importance of high quality materials, electronic and printed 2 The importance of student pacing and student support 3 Continuous assessment of students, and examinations 4 Closing the loop - feedback from students.

  8. How to avoid the ten most frequent EMS pitfalls

    SciTech Connect

    Andrews, W.

    1982-04-19

    It pays to do your homework before investing in an energy management system if you want to avoid the 10 most common pitfalls listed by users, consultants, and manufacturers as: oversimplification, improper maintenance, failure to involve operating personnel, inaccurate savings estimates, failure to include monitoring capability, incompetent or fradulent firms, improper load control, not allowing for a de-bugging period, failure to include manual override, and software problems. The article describes how each of these pitfalls can lead to poor decisions and poor results. (DCK)

  9. Rational manipulation of digital EEG: pearls and pitfalls.

    PubMed

    Seneviratne, Udaya

    2014-12-01

    The advent of digital EEG has provided greater flexibility and more opportunities in data analysis to optimize the diagnostic yield. Changing the filter settings, sensitivity, montages, and time-base are possible rational manipulations to achieve this goal. The options to use polygraphy, video, and quantification are additional useful features. Aliasing and loss of data are potential pitfalls in the use of digital EEG. This review illustrates some common clinical scenarios where rational manipulations can enhance the diagnostic EEG yield and potential pitfalls in the process.

  10. Nicotine replacement therapy

    MedlinePlus

    ... nicotine replacement product, even for a short time. Alternative Names Smoking cessation - nicotine replacement; Tobacco - nicotine replacement therapy References American Cancer Society. Guide to quitting smoking. Last revised February ...

  11. Shoulder replacement - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000178.htm Shoulder replacement - discharge To use the sharing features on this page, please enable JavaScript. You had shoulder replacement surgery to replace the bones of your shoulder ...

  12. Hip replacement - discharge

    MedlinePlus

    ... surgery to replace all or part of your hip joint with an artificial joint called a prosthesis. This ... You're in the Hospital You had a hip joint replacement surgery to replace all or part of ...

  13. Biological treatment strategies for disc degeneration: potentials and shortcomings

    PubMed Central

    Nerlich, Andreas G.; Boos, Norbert

    2006-01-01

    Recent advances in molecular biology, cell biology and material sciences have opened a new emerging field of techniques for the treatment of musculoskeletal disorders. These new treatment modalities aim for biological repair of the affected tissues by introducing cell-based tissue replacements, genetic modifications of resident cells or a combination thereof. So far, these techniques have been successfully applied to various tissues such as bone and cartilage. However, application of these treatment modalities to cure intervertebral disc degeneration is in its very early stages and mostly limited to experimental studies in vitro or in animal studies. We will discuss the potential and possible shortcomings of current approaches to biologically cure disc degeneration by gene therapy or tissue engineering. Despite the increasing number of studies examining the therapeutic potential of biological treatment strategies, a practicable solution to routinely cure disc degeneration might not be available in the near future. However, knowledge gained from these attempts might be applied in a foreseeable future to cure the low back pain that often accompanies disc degeneration and therefore be beneficial for the patient. PMID:16983559

  14. Role of biomechanics on intervertebral disc degeneration and regenerative therapies: What needs repairing in the disc and what are promising biomaterials for its repair?

    PubMed Central

    Iatridis, James C.; Nicoll, Steven B.; Michalek, Arthur J.; Walter, Benjamin A.; Gupta, Michelle S.

    2013-01-01

    Background Context Degeneration and injuries of the intervertebral disc result in large alterations in biomechanical behaviors. Repair strategies using biomaterials can be optimized based on biomechanical and biological requirements. Purpose To review current literature on 1) effects of degeneration, simulated degeneration, and injury on biomechanics of the intervertebral disc with special attention paid to needle puncture injuries which are a pathway for diagnostics and regenerative therapies; and 2) promising biomaterials for disc repair with a focus on how those biomaterials may promote biomechanical repair. Study Design/Setting A narrative review to evaluate the role of biomechanics on disc degeneration and regenerative therapies with a focus on what biomechanical properties need to be repaired and how to evaluate and accomplish such repairs using biomaterials. Model systems for screening of such repair strategies are also briefly described. Methods Papers were selected from two main Pubmed searches using keywords: intervertebral AND biomechanics (1823 articles) and intervertebral AND biomaterials (361 articles). Additional keywords (injury, needle puncture, nucleus pressurization, biomaterials, hydrogel, sealant, tissue engineering) were used to narrow articles to the topics most relevant to this review. Results Degeneration and acute disc injuries have the capacity to influence nucleus pulposus pressurization and annulus fibrosus integrity, which are necessary for effective disc function, and therefore, require repair. Needle injection injuries are of particular clinical relevance with potential to influence disc biomechanics, cellularity, and metabolism, yet these effects are localized or small, and more research is required to evaluate and reduce potential clinical morbidity using such techniques. NP replacement strategies, such as hydrogels, are required to restore NP pressurization or lost volume. AF repair strategies, including crosslinked hydrogels

  15. Gravitoturbulence in magnetized protostellar discs

    NASA Astrophysics Data System (ADS)

    Riols, A.; Latter, H.

    2016-08-01

    Gravitational instability (GI) features in several aspects of protostellar disc evolution, most notably in angular momentum transport, fragmentation, and the outbursts exemplified by FU Ori and EX Lupi systems. The outer regions of protostellar discs may also be coupled to magnetic fields, which could then modify the development of GI. To understand the basic elements of their interaction, we perform local 2D ideal and resistive magnetohydrodynamics simulations with an imposed toroidal field. In the regime of moderate plasma beta, we find that the system supports a hot gravitoturbulent state, characterized by considerable magnetic energy and stress and a surprisingly large Toomre parameter Q ≳ 10. This result has potential implications for disc structure, vertical thickness, ionization, etc. Our simulations also reveal the existence of long-lived and dense `magnetic islands' or plasmoids. Lastly, we find that the presence of a magnetic field has little impact on the fragmentation criterion of the disc. Though our focus is on protostellar discs, some of our results may be relevant for the outer radii of AGN.

  16. Hydrogel discs for digital microfluidics

    PubMed Central

    Fiddes, Lindsey K.; Luk, Vivienne N.; Au, Sam H.; Ng, Alphonsus H. C.; Luk, Victoria; Kumacheva, Eugenia; Wheeler, Aaron R.

    2012-01-01

    Hydrogels are networks of hydrophilic polymer chains that are swollen with water, and they are useful for a wide range of applications because they provide stable niches for immobilizing proteins and cells. We report here the marriage of hydrogels with digital microfluidic devices. Until recently, digital microfluidics, a fluid handling technique in which discrete droplets are manipulated electromechanically on the surface of an array of electrodes, has been used only for homogeneous systems involving liquid reagents. Here, we demonstrate for the first time that the cylindrical hydrogel discs can be incorporated into digital microfluidic systems and that these discs can be systematically addressed by droplets of reagents. Droplet movement is observed to be unimpeded by interaction with the gel discs, and gel discs remain stationary when droplets pass through them. Analyte transport into gel discs is observed to be identical to diffusion in cases in which droplets are incubated with gels passively, but transport is enhanced when droplets are continually actuated through the gels. The system is useful for generating integrated enzymatic microreactors and for three-dimensional cell culture. This paper demonstrates a new combination of techniques for lab-on-a-chip systems which we propose will be useful for a wide range of applications. PMID:22662096

  17. Wear analysis of disc cutters of full face rock tunnel boring machine

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaohuang; Meng, Liang; Sun, Fei

    2014-11-01

    Wear is a major factor of disc cutters' failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine(TBM) to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead(radius for installation); in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians' experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project(excavation length 173 m). The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project(excavation length of 5621 m). The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate(accuracy 16.12%) but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient(accuracy 41%, which is in agreement with the prediction of disc cutters' life in the field). This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

  18. Atomic gas in debris discs

    NASA Astrophysics Data System (ADS)

    Hales, Antonio S.; Barlow, M. J.; Crawford, I. A.; Casassus, S.

    2017-04-01

    We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either Hα, Ca II or Na I, confirming their more evolved nature. Four stars were found to exhibit narrow absorption features near the cores of the photospheric Ca II and Na I D lines (when Na I D data were available). We analyse the characteristics of these spectral features to determine whether they are of circumstellar or interstellar origins. The strongest evidence for circumstellar gas is seen in the spectrum of HD 110058, which is known to host a debris disc observed close to edge-on. This is consistent with a recent ALMA detection of molecular gas in this debris disc, which shows many similarities to the β Pictoris system.

  19. E-Content Development for Languages: Success Factors and Pitfalls

    ERIC Educational Resources Information Center

    De Paepe, Liesbeth

    2014-01-01

    This paper discusses the success factors and pitfalls in development of e-content for languages. The factors discussed draw on several years of experience in developing and implementing 95% distance courses for Dutch as a second language in the adult education sector in Flanders and on PhD research at VUB. The CEFR [Common European Framework of…

  20. Robot-assisted radical prostatectomy: tips, tricks and pitfalls.

    PubMed

    Mottrie, A; De Naeyer, G; Schatteman, P; Frumenzio, E; Rossanese, M; Ficarra, V

    2012-06-01

    In the last decade, we have assisted to the progressive standardization of the surgical technique of robot-assisted radical prostatectomy (RARP). This article describes in details our current surgical technique to perform nerve-sparing RARP. Specifically, we took in consideration the tips, tricks and pitfalls of each step of RARP according to our experience.

  1. Proposal Pitfalls Plaguing Researchers: Can Technical Communicators Make a Difference?

    ERIC Educational Resources Information Center

    Lemanski, Steve

    2014-01-01

    The facts bear out that the odds are against most scientific researchers and scholars--especially those just starting out--in their attempts to win funding for their research projects through their grant proposals. In this article, the author takes a close look at some of the proposal-related problems and pitfalls that have historically challenged…

  2. Pitfalls of Data Analysis. ERIC/AE Digest.

    ERIC Educational Resources Information Center

    Helberg, Clay

    Abuses and misuses of statistics are frequent. This digest attempts to warn against these in three broad classes of pitfalls: sources of bias, errors of methodology, and misinterpretation of results. Sources of bias are conditions or circumstances that affect the external validity of statistical results. In order for a researcher to make…

  3. Common pitfalls in statistical analysis: Linear regression analysis.

    PubMed

    Aggarwal, Rakesh; Ranganathan, Priya

    2017-01-01

    In a previous article in this series, we explained correlation analysis which describes the strength of relationship between two continuous variables. In this article, we deal with linear regression analysis which predicts the value of one continuous variable from another. We also discuss the assumptions and pitfalls associated with this analysis.

  4. Common pitfalls in statistical analysis: Clinical versus statistical significance

    PubMed Central

    Ranganathan, Priya; Pramesh, C. S.; Buyse, Marc

    2015-01-01

    In clinical research, study results, which are statistically significant are often interpreted as being clinically important. While statistical significance indicates the reliability of the study results, clinical significance reflects its impact on clinical practice. The third article in this series exploring pitfalls in statistical analysis clarifies the importance of differentiating between statistical significance and clinical significance. PMID:26229754

  5. Proposal Pitfalls Plaguing Researchers: Can Technical Communicators Make a Difference?

    ERIC Educational Resources Information Center

    Lemanski, Steve

    2014-01-01

    The facts bear out that the odds are against most scientific researchers and scholars--especially those just starting out--in their attempts to win funding for their research projects through their grant proposals. In this article, the author takes a close look at some of the proposal-related problems and pitfalls that have historically challenged…

  6. The Pitfalls and Triumphs of Launching a Charter School.

    ERIC Educational Resources Information Center

    Page, Linda; Levine, Mark

    1996-01-01

    A principal of a charter school in Colorado Springs, Colorado, recounts the triumphs and pitfalls of the school's first year. The school charter lacked a clear-cut avenue for making changes. Intending to create a parent-run school, the founding board (themselves parents) made drastic curricular changes without consulting other parents. Passionate…

  7. Pitfalls and Limitations of Radionuclide Imaging in Endocrinology.

    PubMed

    Agrawal, Kanhaiyalal; Esmail, Abdulredha A H; Gnanasegaran, Gopinath; Navalkissoor, Shaunak; Mittal, Bhagwant Rai; Fogelman, Ignac

    2015-09-01

    Several different techniques, radiopharmaceuticals, and imaging modalities are commonly used in nuclear medicine for studies of endocrine organs. Nuclear medicine is used in the management of benign and malignant thyroid, parathyroid, and neuroendocrine disorders. Thus, it is essential to acknowledge pitfalls and the limitations of nuclear medicine imaging for accurate diagnosis and patient management.

  8. The Pitfalls of Testing in the Quest of Excellence.

    ERIC Educational Resources Information Center

    Goodwin, Coleen R.

    This document presents five scenarios, each referring to a means of assessing learning. These examples are then used to discuss pitfalls faced when tests are used to assess learning, and the conclusion is reached that testing should play a supportive role only, not a major role in the quest for excellence. Effective schools research shows that…

  9. Cases on Global E-Learning Practices: Successes and Pitfalls

    ERIC Educational Resources Information Center

    Sharma, Ramesh C., Ed.; Mishra, Sanjaya, Ed.

    2007-01-01

    "Cases on Global E-Learning Practices: Successes and Pitfalls" looks into global practices of e-learning, examining the successes and failures of e-learning professionals. It provides a judicious mix of practical experiences and research in the form of case studies. Written by experts from all over the globe, this book shows how to…

  10. The ILR Oral Interview: Origins, Applications, Pitfalls, and Implications.

    ERIC Educational Resources Information Center

    Leow, Pardee, Jr.

    1983-01-01

    Describes the original FSI oral interview and the ACTFL/ETS modifications. Discusses: (1) the characteristics of the test, (2) some possible pitfalls in application and their remedies, and (3) some possible long range effects of the oral interview on second language teaching and testing. Provisional generic descriptions for speaking and…

  11. Pseudocarcinomatous hyperplasia involving the ear from gout: a diagnostic pitfall.

    PubMed

    Morrissey, Kelly A; Garcia-Albea, Victoria; Goldberg, Lynne J

    2014-01-01

    The ear is a characteristic location for deposition of uric acid in patients with gout. Pseudocarcinomatous hyperplasia has not been described in this location. We report three patients with tophaceous gout on the ear whose biopsies exhibited epidermal hyperplasia mimicking squamous cell carcinoma, in order to call attention to this potential diagnostic pitfall.

  12. Cases on Global E-Learning Practices: Successes and Pitfalls

    ERIC Educational Resources Information Center

    Sharma, Ramesh C., Ed.; Mishra, Sanjaya, Ed.

    2007-01-01

    "Cases on Global E-Learning Practices: Successes and Pitfalls" looks into global practices of e-learning, examining the successes and failures of e-learning professionals. It provides a judicious mix of practical experiences and research in the form of case studies. Written by experts from all over the globe, this book shows how to…

  13. Coevolution of binaries and circumbinary gaseous discs

    NASA Astrophysics Data System (ADS)

    Fleming, David P.; Quinn, Thomas R.

    2017-01-01

    The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disc and how the disc and binary interact and change as a result. The central binary excites resonances in the surrounding protoplanetary disc which drive evolution in both the binary orbital elements and in the disc. To probe how these interactions impact binary eccentricity and disc structure evolution, N-body smooth particle hydrodynamics simulations of gaseous protoplanetary discs surrounding binaries based on Kepler 38 were run for 104 binary periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disc via a parametric instability and excite disc eccentricity growth. Eccentric binaries strongly couple to the disc causing eccentricity growth for both the disc and binary. Discs around sufficiently eccentric binaries which strongly couple to the disc develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance which corresponds to an alignment of gas particle longitude of periastrons. All systems display binary semimajor axis decay due to dissipation from the viscous disc.

  14. Kineflex (Centurion) Lumbar Disc Prosthesis: Insertion Technique and 2-Year Clinical Results in 100 Patients

    PubMed Central

    Weinberg, Ian R.; Sliwa, Karen; Sweet, Barry MBE; de Villiers, Malan

    2007-01-01

    Background The Kineflex lumbar disc is a mechanical, unconstrained, re-centering disc prosthesis developed in South Africa. The first implantation took place in October 2002. We present a single-center, prospective, longitudinal study of the first 100 patients treated with the Kineflex lumbar disc. Our objective was to evaluate the insertion technique, clinical outcomes, and patient satisfaction at 2 years postimplantation in 100 consecutive patients with 132 (68 single- and 32 2-level) Kineflex lumbar disc replacements. Methods We determined the exact central placement of all disc implants in the coronal and midsagittal planes. We measured clinical outcome with the Oswestry disability index (ODI), our own questionnaire, and the time needed to return to work. All patients received radiological and clinical follow-up assessments for 2 years after the index procedure. Results Forty-three patients were female. The mean age of the patients at operation was 44.9 years (range, 23–63 years). Postoperative hospitalization averaged 2.8 days (range, 2 to 8 days). All patients who were employed before surgery returned to work 31 ± 16.8 days after the operation. Fifty-six percent of operated disc levels had intervertebral disc heights of less than 5 mm. A 2-year clinical outcome was available for 98 of the 100 patients (58 excellent, 30 good, 7 fair, 3 poor). The ODI score improved from 47.8 ± 16.0 preoperatively to 14.2 ± 14.0 (P < .01) at 2 years. At 2 years, 95% of disc implants were radiologically in the ideal position. The insertion technique, with a released prosthetic mechanism for final placement, allowed ideal placement in the sagittal plane in 98% of discs. The radiographic placement accuracy achieved was equal in patients with preoperative intervertebral disc height below and above 5 mm. Conclusions Good short-term clinical results were achieved with the Kineflex disc in a heterogeneous patient group with a high number of patients with advanced disc

  15. [Total Elbow Replacement - Implantation of the Latitude Prosthesis (Tornier)].

    PubMed

    Hackl, M; Wegmann, K; Leschinger, T; Ries, C; Burkhart, K J; Müller, L

    2015-10-01

    Due to technical progress, the indication for total elbow arthroplasty could be expanded in recent years. As a result, the demand regarding functionality and mobility of the replaced joint has risen as well. Elbow arthroplasty has to be considered as technically demanding. Only with detailed knowledge of this surgical procedure and its possible intraoperative pitfalls can one provide the best possible results. In this instructional video we explain the implantation of the Latitude elbow prosthesis (Tornier) putting emphasis on the correct approach as well as implantation of the prosthesis and subsequent wound closure.

  16. Eddy current braking experiment using brake disc from aluminium series of A16061 and A17075

    NASA Astrophysics Data System (ADS)

    Baharom, M. Z.; Nuawi, M. Z.; Priyandoko, G.; Harris, S. M.

    2012-09-01

    The electromagnetic braking using eddy current was studied, focused on two series of aluminium as the brake disc which are A16061 and A17075. This paper presents the comparison for both series in a few varied parameters related to eddy current braking such as air-gap, number of turns and brake disc thickness. Optical tachometer has been used along with PULSE analyzer to capture the speed (rpm) and time (s). The findings shows that the smaller the air-gap, the larger of electromagnet turns and the thicker disc thickness is, will generate higher braking torque to stop the rotational motion of disc brake and give great performance for eddy current braking. Thos parameters that been evaluated also addressed a potential on expanding this knowledge to develop an electromagnetic braking system to replace the conventional braking system.

  17. Measurement of position deviation and eccentricity for μ-disc-type inductive micro-motor

    NASA Astrophysics Data System (ADS)

    Lin, Chih-Che; Tsai, Nan-Chyuan

    2015-12-01

    An innovative capacitive gap-sensing readout circuit to replace traditional gap sensor is designed to measure the motion of the levitated micro-disc embedded in an inductive micro-motor. Twelve equivalent capacitor pairs are constructed to detect the position deviation of the disc. As the position deviation of disc occurs, the capacitances of the corresponding capacitor pairs are altered. In addition, by applying the effects of inertial force and centrifugal force, an innovative non-contact measurement method to quantify the unbalance degree of the micro-disc, i.e., eccentricity, is also proposed. By commercial computer simulations and realistic experiments undertaken, the performance of the proposed capacitive gap-sensing readout circuit has been successfully verified. The mean of output voltage of gap-sensing readout circuit is about 327 mV under the position deviation of the disc being 8 μm. Moreover, the unbalance degree of the disc is approximately proportional to the square of the position deviation of the disc.

  18. Minimally Invasive Anterior Cervical Discectomy Without Fusion to Treat Cervical Disc Herniations in Patients with Previous Cervical Fusions.

    PubMed

    Jacobson, Robert E; Granville, Michelle; Berti, Aldo

    2017-04-03

    Adjacent level cervical disc disease and secondarily progressive disc space degeneration that develops years after previously successful anterior cervical fusion at one or more levels is a common, but potentially complex problem to manage. The patient is faced with the option of further open surgery which involves adding another level of disc removal with fusion, posterior decompression, and stabilization, or possibly replacing the degenerated disc with an artificial disc construct. These three cases demonstrate that some patients, especially after minor trauma, may have small herniated discs as the cause for their new symptoms rather than progressive segmental degeneration. Each patient became symptomatic after minor trauma three to six years after the original fusion and had no or minimal radiologic changes of narrowing of the disc or spur formation commonly seen in adjacent level disease, but rather had magnetic resonance imaging (MRI) findings typical of small herniated discs. After failing multiple months of conservative treatment they were offered surgery as an option. Subsequently, all three were successfully treated with minimal anterior discectomy without fusion. There are no reports in the literature of using minimal anterior cervical discectomy without fusion in previous fused patients. This report reviews the background of adjacent level cervical disease, the various biomechanical explanations for developing a new disc herniation rather than progressive segmental degeneration, and how anterior cervical discectomy without fusion can be an option in these patients.

  19. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... of antimicrobic-impregnated paper discs used to measure by a disc-agar diffusion technique or a disc... antimicrobial agents. In the disc-agar diffusion technique, bacterial susceptibility is ascertained by directly...

  20. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... of antimicrobic-impregnated paper discs used to measure by a disc-agar diffusion technique or a disc... antimicrobial agents. In the disc-agar diffusion technique, bacterial susceptibility is ascertained by directly...

  1. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... of antimicrobic-impregnated paper discs used to measure by a disc-agar diffusion technique or a disc... antimicrobial agents. In the disc-agar diffusion technique, bacterial susceptibility is ascertained by directly...

  2. 21 CFR 866.1620 - Antimicrobial susceptibility test disc.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... of antimicrobic-impregnated paper discs used to measure by a disc-agar diffusion technique or a disc... antimicrobial agents. In the disc-agar diffusion technique, bacterial susceptibility is ascertained by directly...

  3. Determination of the intervertebral disc space from CT images of the lumbar spine

    NASA Astrophysics Data System (ADS)

    Korez, Robert; Å tern, Darko; Likar, Boštjan; Pernuš, Franjo; Vrtovec, Tomaž

    2014-03-01

    Degenerative changes of the intervertebral disc are among the most common causes of low back pain, where for individuals with significant symptoms surgery may be needed. One of the interventions is the total disc replacement surgery, where the degenerated disc is replaced by an artificial implant. For designing implants with good bone contact and continuous force distribution, the morphology of the intervertebral disc space and vertebral body endplates is of considerable importance. In this study we propose a method for the determination of the intervertebral disc space from three-dimensional (3D) computed tomography (CT) images of the lumbar spine. The first step of the proposed method is the construction of a model of vertebral bodies in the lumbar spine. For this purpose, a chain of five elliptical cylinders is initialized in the 3D image and then deformed to resemble vertebral bodies by introducing 25 shape parameters. The parameters are obtained by aligning the chain to the vertebral bodies in the CT image according to image intensity and appearance information. The determination of the intervertebral disc space is finally achieved by finding the planes that fit the endplates of the obtained parametric 3D models, and placing points in the space between the planes of adjacent vertebrae that enable surface reconstruction of the intervertebral disc space. The morphometric analysis of images from 20 subjects yielded 11:3 +/- 2:6, 12:1 +/- 2:4, 12:8 +/- 2:0 and 12:9 +/- 2:7 cm3 in terms of L1-L2, L2-L3, L3-L4 and L4-L5 intervertebral disc space volume, respectively.

  4. 26 CFR 1.246-4 - Dividends from a DISC or former DISC.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 3 2010-04-01 2010-04-01 false Dividends from a DISC or former DISC. 1.246-4... TAX (CONTINUED) INCOME TAXES Special Deductions for Corporations § 1.246-4 Dividends from a DISC or former DISC. The deduction provided in section 243 (relating to dividends received by corporations) is...

  5. Generation of inclined protoplanetary discs and misaligned planets through mass accretion - I. Coplanar secondary discs

    NASA Astrophysics Data System (ADS)

    Xiang-Gruess, M.; Kroupa, P.

    2017-10-01

    We study the three-dimensional (3D) evolution of a viscous protoplanetary disc that accretes gas material from a second protoplanetary disc during a close encounter in an embedded star cluster. The aim is to investigate the capability of the mass accretion scenario to generate strongly inclined gaseous discs that could later form misaligned planets. We use smoothed particle hydrodynamics to study mass transfer and disc inclination for passing stars and circumstellar discs with different masses. We explore different orbital configurations to find the parameter space that allows significant disc inclination generation. Thies et al. suggested that significant disc inclination and disc or planetary system shrinkage can generally be produced by the accretion of external gas material with a different angular momentum. We found that this condition can be fulfilled for a large range of gas mass and angular momentum. For all encounters, mass accretion from the secondary disc increases with decreasing mass of the secondary proto-star. Thus, higher disc inclinations can be attained for lower secondary stellar masses. Variations of the secondary disc's orientation relative to the orbital plane can alter the disc evolution significantly. The results taken together show that mass accretion can change the 3D disc orientation significantly resulting in strongly inclined discs. In combination with the gravitational interaction between the two star-disc systems, this scenario is relevant for explaining the formation of highly inclined discs that could later form misaligned planets.

  6. Simulations of magnetic fields in isolated disc galaxies

    NASA Astrophysics Data System (ADS)

    Pakmor, Rüdiger; Springel, Volker

    2013-06-01

    Magnetic fields are known to be dynamically important in the interstellar medium of our own Galaxy, and they are ubiquitously observed in diffuse gas in the haloes of galaxies and galaxy clusters. Yet, magnetic fields have typically been neglected in studies of the formation of galaxies, leaving their global influence on galaxy formation largely unclear. Here we extend our magnetohydrodynamics (MHD) implementation in the moving-mesh code AREPO to cosmological problems which include radiative cooling and the formation of stars. In particular, we replace our previously employed divergence cleaning approach with a Powell eight-wave scheme, which turns out to be significantly more stable, even in very dynamic environments. We verify the improved accuracy through simulations of the magneto-rotational instability in accretion discs, which reproduce the correct linear growth rate of the instability. Using this new MHD code, we simulate the formation of isolated disc galaxies similar to the Milky Way using idealized initial conditions with and without magnetic fields. We find that the magnetic field strength is quickly amplified in the initial central starburst and the differential rotation of the forming disc, eventually reaching a saturation value. At this point, the magnetic field pressure in the interstellar medium becomes comparable to the thermal pressure, and a further efficient growth of the magnetic field strength is prevented. The additional pressure component leads to a lower star formation rate at late times compared to simulations without magnetic fields, and induces changes in the spiral arm structures of the gas disc. In addition, we observe highly magnetized fountain-like outflows from the disc. These results are robust with numerical resolution and are largely independent of the initial magnetic seed field strength assumed in the initial conditions, as the amplification process is rapid and self-regulated. Our findings suggest an important influence of

  7. Radiative transfer modelling of parsec-scale dusty warped discs

    NASA Astrophysics Data System (ADS)

    Jud, H.; Schartmann, M.; Mould, J.; Burtscher, L.; Tristram, K. R. W.

    2017-02-01

    Warped discs have been found on (sub-)parsec scale in some nearby Seyfert nuclei, identified by their maser emission. Using dust radiative transfer simulations, we explore their observational signatures in the infrared in order to find out whether they can partly replace the molecular torus. Strong variations of the brightness distributions are found, depending on the orientation of the warp with respect to the line of sight. Whereas images at short wavelengths typically show a disc-like and a point source component, the warp itself only becomes visible at far-infrared wavelengths. A similar variety is visible in the shapes of the spectral energy distributions. Especially for close to edge-on views, the models show silicate feature strengths ranging from deep absorption to strong emission for variations of the lines of sight towards the warp. To test the applicability of our model, we use the case of the Circinus galaxy, where infrared interferometry has revealed a highly elongated emission component matching a warped maser disc in orientation and size. Our model is for the first time able to present a physical explanation for the observed dust morphology as coming from the active galactic nuclei heated dust. As opposed to available torus models, a warped disc morphology produces a variety of silicate feature shapes for grazing lines of sight, close to an edge-on view. This could be an attractive alternative to a claimed change of the dust composition for the case of the nearby Seyfert 2 galaxy NGC 1068, which harbours a warped maser disc as well.

  8. A Low-Cost Auto-Stop Hydraulic Press for Making KBr Disc

    NASA Astrophysics Data System (ADS)

    Hon, Ping-Kay

    1998-05-01

    A hydraulic press fitted with an adjustable torque wrench, together with a stand made of iron bars will form an auto-stop hydraulic press for making KBr disc in IR studies. Total material cost is about $100. All parts are readily available from the local hardware stores. The modified torque wrench is also useful to replace the lever in the standard laboratory press.

  9. 37 CFR 1.52 - Language, paper, writing, margins, compact disc specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... permanent dark ink or its equivalent; and (v) Presented in a form having sufficient clarity and contrast... submitted may contain alterations that do not introduce matter that would have been new matter in the prior... new matter. The compact disc and copy must be labeled “COPY 1 REPLACEMENT MM/DD/YYYY” (with the month...

  10. Photoevaporating transitional discs and molecular cloud cores

    NASA Astrophysics Data System (ADS)

    Li, Min; Sui, Ning

    2017-04-01

    We investigate the evolution of photoevaporating protoplanetary discs including mass influx from molecular cloud cores. We examine the influence of cloud core properties on the formation and evolution of transitional discs. We use one-dimensional thin disc assumption and calculate the evolution of the protoplanetary disc. The effects of X-ray photoevaporation are also included. Our calculations suggest that most discs should experience the transitional disc phase within 10 Myr. The formation time of a gap and its initial location are functions of the properties of the cloud cores. In some circumstances, discs can open two gaps by photoevaporation alone. The two gaps form when the gas in the disc can expand to large radius and if the mass at large radius is sufficiently small. The surface density profile of the disc determines whether the two gaps can form. Since the structure of a disc is determined by the properties of a molecular cloud core, the core properties determine the formation of two gaps in the disc. We further find that even when the photoevaporation rate is reduced to 10 per cent of the standard value, two gaps can still form in the disc. The only difference is that the formation time is delayed.

  11. Hydrodynamic ablation of protoplanetary discs via supernovae

    NASA Astrophysics Data System (ADS)

    Close, J. L.; Pittard, J. M.

    2017-07-01

    We present three-dimensional simulations of a protoplanetary disc subject to the effect of a nearby (0.3 pc distant) supernova (SN), using a time-dependent flow from a one-dimensional numerical model of the supernova remnant (SNR), in addition to constant peak ram pressure simulations. Simulations are performed for a variety of disc masses and inclination angles. We find disc mass-loss rates that are typically 10-7-10-6 M⊙ yr-1 (but they peak near 10-5 M⊙ yr-1 during the 'instantaneous' stripping phase) and are sustained for around 200 yr. Inclination angle has little effect on the mass-loss unless the disc is close to edge-on. Inclined discs also strip asymmetrically with the trailing edge ablating more easily. Since the interaction lasts less than one outer rotation period, there is not enough time for the disc to restore its symmetry, leaving the disc asymmetrical after the flow has passed. Of the low-mass discs considered, only the edge-on disc is able to survive interaction with the SNR (with 50 per cent of its initial mass remaining). At the end of the simulations, discs that survive contain fractional masses of SN material up to 5 × 10-6. This is too low to explain the abundance of short-lived radionuclides in the early Solar system, but a larger disc and the inclusion of radiative cooling might allow the disc to capture a higher fraction of SN material.

  12. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  13. Optical Disc Applications in Libraries.

    ERIC Educational Resources Information Center

    Andre, Pamela Q. J.

    1989-01-01

    Discusses a variety of library applications of optical disc storage technology, including CD-ROM, digital videodisc, and WORM. Research and development projects at the Library of Congress, National Library of Medicine, and National Agricultural Library are described, products offered by library networks are reviewed, and activities in academic and…

  14. Electromagnetic Levitation of a Disc

    ERIC Educational Resources Information Center

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  15. Twin Disc Gear Tooth Simulator

    DTIC Science & Technology

    1994-05-01

    temperature testing, i.e., aluminum, titanium alloys, or magnesium with Krytox . * Use adequate forced-draft ventilation. * Prior to conducting any...ultrasonic cleaner charged with Stoddard solvent. 2. Prior to installation, wipe all disc surfaces with a lint-free cloth dampened with Stoddard solvent

  16. Intervertebral disc calcifications in children.

    PubMed

    Beluffi, G; Fiori, P; Sileo, C

    2009-03-01

    This study was done to assess the presence of both asymptomatic and symptomatic intervertebral disc calcifications in a large paediatric population. We retrospectively reviewed the radiographs taken during the past 26 years in children (age 0-18 years) undergoing imaging of the spine or of other body segments in which the spine was adequately depicted, to determine possible intervertebral disc calcifications. The following clinical evaluation was extrapolated from the patients' charts: presence of spinal symptoms, history of trauma, suspected or clinically evident scoliosis, suspected or clinically evident syndromes, bone dysplasias, and pre- or postoperative chest or abdominal X-rays. We detected intervertebral disc calcifications in six patients only. Five calcifications were asymptomatic (one newborn baby with Patau syndrome; three patients studied to rule out scoliosis, hypochondroplasia and syndromic traits; one for dyspnoea due to sunflower seeds inhalation). Only one was symptomatic, with acute neck pain. Calcifications varied in number from one in one patient to two to five in the others. Apart from the calcification in the patient with cervical pain, all calcifications were asymptomatic and constituted an incidental finding (particularly those detected at the thoracic level in the patient studied for sunflower-seed inhalation). Calcification shapes were either linear or round. Our series confirms that intervertebral disc calcifications are a rare finding in childhood and should not be a source of concern: symptomatic calcifications tend to regress spontaneously within a short time with or without therapy and immobilisation, whereas asymptomatic calcifications may last for years but disappear before the age of 20 years. Only very few cases, such as those of medullary compression or severe dysphagia due to anterior herniation of cervical discs, may require surgical procedures.

  17. The relationship between quantitative measures of disc height and disc signal intensity with Pfirrmann score of disc degeneration.

    PubMed

    Salamat, Sara; Hutchings, John; Kwong, Clemens; Magnussen, John; Hancock, Mark J

    2016-01-01

    To assess the relationship between quantitative measures of disc height and signal intensity with the Pfirrmann disc degeneration scoring system and to test the inter-rater reliability of the quantitative measures. Participants were 76 people who had recently recovered from their last episode of acute low back pain and underwent MRI scan on a single 3T machine. At all 380 lumbar discs, quantitative measures of disc height and signal intensity were made by 2 independent raters and compared to Pfirrmann scores from a single radiologist. For quantitative measures of disc height and signal intensity a "raw" score and 2 adjusted ratios were calculated and the relationship with Pfirrmann scores was assessed. The inter-tester reliability of quantitative measures was also investigated. There was a strong linear relationship between quantitative disc signal intensity and Pfirrmann scores for grades 1-4, but not for grades 4 and 5. For disc height only, Pfirrmann grade 5 had significantly reduced disc height compared to all other grades. Results were similar regardless of whether raw or adjusted scores were used. Inter-rater reliability for the quantitative measures was excellent (ICC > 0.97). Quantitative measures of disc signal intensity were strongly related to Pfirrmann scores from grade 1 to 4; however disc height only differentiated between grade 4 and 5 Pfirrmann scores. Using adjusted ratios for quantitative measures of disc height or signal intensity did not significantly alter the relationship with Pfirrmann scores.

  18. A Structurally and Functionally Biomimetic Biphasic Scaffold for Intervertebral Disc Tissue Engineering

    PubMed Central

    Choy, Andrew Tsz Hang; Chan, Barbara Pui

    2015-01-01

    Tissue engineering offers high hopes for the treatment of intervertebral disc (IVD) degeneration. Whereas scaffolds of the disc nucleus and annulus have been extensively studied, a truly biomimetic and mechanically functional biphasic scaffold using naturally occurring extracellular matrix is yet to be developed. Here, a biphasic scaffold was fabricated with collagen and glycosaminoglycans (GAGs), two of the most abundant extracellular matrix components in the IVD. Following fabrication, the scaffold was characterized and benchmarked against native disc. The biphasic scaffold was composed of a collagen-GAG co-precipitate making up the nucleus pulposus-like core, and this was encapsulated in multiple lamellae of photochemically crosslinked collagen membranes comprising the annulus fibrosus-like lamellae. On mechanical testing, the height of our engineered disc recovered by ~82-89% in an annulus-independent manner, when compared with the 99% recovery exhibited by native disc. The annulus-independent nature of disc height recovery suggests that the fluid replacement function of the engineered nucleus pulposus core might mimic this hitherto unique feature of native disc. Biphasic scaffolds comprised of 10 annulus fibrosus-like lamellae had the best overall mechanical performance among the various designs owing to their similarity to native disc in most aspects, including elastic compliance during creep and recovery, and viscous compliance during recovery. However, the dynamic mechanical performance (including dynamic stiffness and damping factor) of all the biphasic scaffolds was similar to that of the native discs. This study contributes to the rationalized design and development of a biomimetic and mechanically viable biphasic scaffold for IVD tissue engineering. PMID:26115332

  19. Complications and reoperations of the SB Charité lumbar disc prosthesis: experience in 75 patients

    PubMed Central

    Punt, Ilona M.; Visser, Violette M.; van Rhijn, Lodewijk W.; Kurtz, Steven M.; Antonis, Jop; Schurink, Geert Willem H.

    2007-01-01

    Artificial disc prosthesis show fair to good short- and mid-term results. Long-term results are becoming apparent now, however, the incidence of late complications with this procedure remain poorly understood. In this report we will analyse late complications and discuss our experiences with salvage operations in patients with persistent pain after SB Charité disc prosthesis implantation. Seventy-five patients with persistent leg and back pain after insertion of an artificial disc prosthesis were enrolled in the study. In this negative selection frequently occurring late-complications were subsidence, wear, adjacent disc degeneration, facet joint degeneration and migration. In 15 patients we performed a posterior fusion without disc removal, and in 22 patients we removed 26 prostheses and performed a posterior and anterior fusion. The visual analogue scale (VAS) and Oswestry were examined before the salvage operation and after a follow-up period of at least 1 year, which is not yet available in all patients. The VAS and Oswestry decreased in the posterior group (n = 10) respectively from 8.0 (SD 0.9) to 6.3 (SD 2.1) and from 57.0 (SD 17.0) to 44.6 (SD 20.4); and in the disc removal group (n = 14) respectively from 8.0 (SD 0.9) to 5.6 (SD 2.7) and from 56.3 (SD 14.0) to 43.0 (SD 20.7). Serious late complications may occur following total disc replacement. Removal of the SB Charité artificial disc is feasible but with inherent risks. Removal of the disc prosthesis gives slightly better results than posterior fusion alone after a follow-up of at least 1 year. PMID:17929065

  20. Peripheral Disc Margin Shape and Internal Disc Derangement: Imaging Correlation in Significantly Painful Discs Identified at Provocation Lumbar Discography

    PubMed Central

    Bartynski, W.S.; Rothfus, W.E.

    2012-01-01

    Summary Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741

  1. [Optic disc granuloma secondary to sarcoidosis].

    PubMed

    Qu-Knafo, L; Auregan-Giocanti, A

    2017-02-01

    We report a case of optic disc granuloma due to sarcoidosis. A 64-year-old, caucasian female with a history of pulmonary sarcoidosis presented with a vision loss on her left eye. The ophthalmologic examination revealed a discrete optic disc infiltrate compatible with the diagnosis of optic disc granuloma. Fluorescein angiography showed diffusion and impregnation of the granuloma without vascularitis. The optical coherence tomography demonstrated a homogenous and isoreflective lesion at the optic disc. The patient recovered her visual acuity after systemic corticosteroid treatment. Isolated optic disc granuloma is a rare condition of ocular sarcoidosis.

  2. Sealing arrangement with annular flexible disc

    DOEpatents

    Pennell, William E.; Honigsberg, Charles A.

    1983-01-01

    Fluid sealing arrangements including an annular shaped flexible disc having enlarged edges disposed within channel-shaped annular receptacles which are spaced from one another. The receptacles form an annular region for contacting and containing the enlarged edges of the disc, and the disc is preloaded to a conical configuration. The disc is flexibly and movably supported within the receptacles so that unevenly distributed relative motion between the components containing the receptacles is accommodated without loss of sealing contact between the edges of the disc and the walls of the receptacles.

  3. Planetary migration in weakly magnetized turbulent discs

    NASA Astrophysics Data System (ADS)

    Baruteau, C.; Fromang, S.; Nelson, R. P.; Masset, F.

    2011-12-01

    In laminar viscous disc models, the migration of protoplanets embedded in their nascent protoplanetary discs may be directed inwards or outwards, depending on the relative magnitude of the Lindblad and corotation torques. The long-term evolution of the corotation torque is intimately related to diffusion processes inside the planet's horseshoe region. This communication examines the properties of the corotation torque in discs where magnetohydrodynamic (MHD) turbulence develops as a result of the magnetorotational instability (MRI), considering a weak initial toroidal magnetic field. We show that the differential Lindblad torque takes very similar values in MHD turbulent and laminar viscous discs, and there exists an unsaturated corotation torque in MHD turbulent discs.

  4. [Imaging monitors--requirements and pitfalls].

    PubMed

    Simmler, R

    2013-11-01

    When applying the standard DIN V 6868-57 rule "acceptance testing for image display devices" it always comes to misunderstandings in the practical implementation. In a brief summary the most important requirements are presented. With the pending replacement of DIN V 6868-57 by DIN 6868-157 "acceptance and constancy tests of image display systems in their environment" there will be fundamental changes. Future requirements are presented as examples. Besides the introduction of a classroom concept and new test images, the focus of the standard is aligned with the image display system. This change places new demands on the management concept of picture archiving and communication system (PACS) workstations. For testing the unit, consisting of a computer system, video card, operating system and image display equipment only one organizational unit should be responsible.

  5. Nubac Disc Arthroplasty: Preclinical Studies and Preliminary Safety and Efficacy Evaluations

    PubMed Central

    Songer, Matthew; Pimenta, Luis; Werner, Dieter; Reyes-Sanchez, Alejandro; Balsano, Massimo; Agrillo, Umberto; Coric, Domagoj; Davenport, Kenneth; Yuan, Hansen

    2007-01-01

    Background Disc arthroplasty is gaining popularity for treatment of low-back pain caused by degenerative disc disease (DDD). It can involve total disc replacement or partial disc or nucleus replacement (or augmentation). Compared with total disc replacement, nucleus replacement is less invasive, has less surgical risk, has faster postoperative recovery, and doesn't “burn bridges” should further surgery be required. However, nucleus replacement has a high risk of implant expulsion because the device is not fixed to the vertebrae. Nubac is the first polyetheretherketone (PEEK)-on-PEEK articulated disc arthroplasty device designed to optimally restore the lumbar anatomy and biomechanics. Methods ISO 10993 standards were used to evaluate the biocompatibility of the PEEK material. Chemical and thermal–mechanical tests and in vivo study assessed PEEK's biostability after exposure to high g irradiation and harsh oxidative conditions. Biomechanical tests to evaluate kinematic properties and anatomical restoration of the implanted lumbar motion segments and implant expulsion risk assessments were performed with a human cadaveric model. Because of the novelty of PEEK-on-PEEK as a self-mating articulating material, extensive wear tests were conducted with unidirectional and coupled motions. Static and fatigue strength also were tested. Animal study with a baboon model was conducted with gross, radiographic, biomechanical, and histological evaluations at 6 and 12 months postoperatively. Preliminary clinical data were collected through a prospective multicenter cohort study. Results PEEK demonstrated exceptional biocompatibility and biodurability. Nubac restored disc height and motion segment range of motion. The unique articulating design of the Nubac demonstrated low risk of implant expulsion in a human cadaveric model. Wear tests showed that the Nubac has minimal wear and compares favorably to other disc arthroplasty materials. The Nubac also had excellent static and

  6. [Spinal instrumentation, source of progress, but also revealing pitfalls].

    PubMed

    Dubousset, Jean

    2003-01-01

    addition the noticed improvements on the biological field for fusion with bone activators like BMP, Hydroxyapatite, or bone substitutes like bio-active ceramics will probably help for fusion and decrease necessity of bone grafting. It is the same about disc regeneration which is on the way. Finally it is evident that the first steps already done for spinal surgery avoiding fusion will extend.--For children and growing spine, the challenge is major, but with memory metal instruments, laser precise destruction of abnormal growing structures as well as posterior flexible instrumentation avoiding stripping of the periosteum and leaving integrity of the disc and facet joints function, improvements are also on the way.--For adult and degenerative spinal deformities and pain, the development of spinal arthroplasty already done for the disc replacement will improve as well as for the posterior joints units where artificial ligaments experience will be replaced by real artificial joints still on experiment. In conclusion, some general biological medical questions are still waiting for answers:--Neurology and erect posture--Growth and degeneration--Malignancy (comprehension and control)--Pain and suffering. And of course what is the fact of the genetics for all of these problems: plenty of work for the future.

  7. Three-piece Inflatable Penile Prosthesis: Surgical Techniques and Pitfalls

    PubMed Central

    Al-Enezi, Ahmad; Al-Khadhari, Sulaiman; Al-Shaiji, Tariq F.

    2011-01-01

    Penile prosthesis surgery plays a vital role in the treatment of erectile dysfunction (ED). As far as outcome is concerned, it is one of the most rewarding procedures for both patients and surgeons. We describe our surgical technique for implantation of the three-piece inflatable penile prosthesis and point out the major surgical pitfalls accompanying this procedure and their specific management. The psychological outcome of penile prosthesis surgery is also discussed. Different surgical approaches are available when performing the procedure. A number of procedure-related problems can be encountered and a thorough knowledge of these is of paramount importance. Penile prosthesis surgery has a favorable psychological outcome. Surgery for implantation of an inflatable penile prosthesis is a rewarding procedure, with a high yield of patient satisfaction. Urologists should have thorough understanding of the surgical pitfalls peculiar to this procedure and their management. PMID:22413049

  8. Herpetological Monitoring Using a Pitfall Trapping Design in Southern California

    USGS Publications Warehouse

    Fisher, Robert; Stokes, Drew; Rochester, Carlton; Brehme, Cheryl; Hathaway, Stacie; Case, Ted

    2008-01-01

    The steps necessary to conduct a pitfall trapping survey for small terrestrial vertebrates are presented. Descriptions of the materials needed and the methods to build trapping equipment from raw materials are discussed. Recommended data collection techniques are given along with suggested data fields. Animal specimen processing procedures, including toe- and scale-clipping, are described for lizards, snakes, frogs, and salamanders. Methods are presented for conducting vegetation surveys that can be used to classify the environment associated with each pitfall trap array. Techniques for data storage and presentation are given based on commonly use computer applications. As with any study, much consideration should be given to the study design and methods before beginning any data collection effort.

  9. Taming Healthcare Costs: Promise and Pitfalls for Women's Health

    PubMed Central

    Glynn, Amy; MacKenzie, Rose

    2016-01-01

    Abstract When it comes to healthcare, women are often the primary decision makers for their families. Therefore, focusing on women and their health needs can have a profound effect on health reform efforts to control costs and improve quality for all segments of the population. The promise and pitfalls of cost containment reform in Massachusetts can serve as an informative case study for policymakers at the local, state, and federal levels as they attempt to reduce costs while maintaining quality of care. Massachusetts cost containment law, Chapter 224, seeks to control the healthcare cost growth through innovative approaches to increase efficiency and transparency including the adoption of new delivery system models, investments in wellness and prevention programs, and implementation of standard quality and evaluation measures. In this paper, we outline four approaches to delivering on the promise of cost containment reform to maximize women's access to comprehensive, quality healthcare while avoiding the pitfalls of cost containment's adverse impact on women's health. PMID:26488183

  10. [Reading medical articles--what pitfalls to avoid].

    PubMed

    Rodondi, Nicolas; Cornuz, Jacques

    2007-11-28

    Critical reading and careful interpretation of results of the medical literature is a difficult task for primary care physicians. Being aware of common potential pitfalls that may bias results of a study is helpful. Among common pitfalls, odds ratios are often interpreted as relative risks, which overestimate the impact of a risk factor. Randomized controlled trials assessing the effectiveness of a new drug or a new target disease often use surrogate markers instead of clinical events as outcomes. Results of these trials should be considered with caution before using their results for clinical practice. For screening, observational studies often yield potentially biased or conflicting results. As clinical guidelines and expert opinions are often conflicting, primary care physicians should wait for results of large clinical trials in clinical events before changing their practice for screening or new drugs.

  11. Medical abortion in primary care: pitfalls and benefits.

    PubMed

    Boersma, A A; Meyboom-de Jong, B

    2009-12-01

    We describe five pitfalls of medical abortion: ectopic pregnancy not terminated after misoprostol, but without negative side-effects; long-term vaginal blood loss with suspicious retained products which disappeared spontaneously; a patient with uterus myomatatosus with severe pain and retained products in the uterus; repetition of misoprostol because of retained products in the uterus after two weeks and an allergic reaction to methotrexate. Despite these pitfalls, there are enough benefits to consider medical abortion with methotrexate and misoprostol as a safe method with a high success rate of more than 91% and a good alternative for surgical abortion. An invasive procedure is not necessary, there are no long-term complications and it can be performed at an earlier stage, which makes it more acceptable in society. In Curaçao, where abortion is legally restricted, medical abortion is performed with methotrexate and misoprostol. In countries where abortion is legal, mifepristone and misoprostol are the first choice.

  12. Pitfalls to avoid when using phage display for snake toxins.

    PubMed

    Laustsen, Andreas Hougaard; Lauridsen, Line Præst; Lomonte, Bruno; Andersen, Mikael Rørdam; Lohse, Brian

    2017-02-01

    Antivenoms against bites and stings from snakes, spiders, and scorpions are associated with immunological side effects and high cost of production, since these therapies are still derived from the serum of hyper-immunized production animals. Biotechnological innovations within envenoming therapies are thus warranted, and phage display technology may be a promising avenue for bringing antivenoms into the modern era of biologics. Although phage display technology represents a robust and high-throughput approach for the discovery of antibody-based antitoxins, several pitfalls may present themselves when animal toxins are used as targets for phage display selection. Here, we report selected critical challenges from our own phage display experiments associated with biotinylation of antigens, clone picking, and the presence of amber codons within antibody fragment structures in some phage display libraries. These challenges may be detrimental to the outcome of phage display experiments, and we aim to help other researchers avoiding these pitfalls by presenting their solutions.

  13. Thermochemical modelling of brown dwarf discs

    NASA Astrophysics Data System (ADS)

    Greenwood, A. J.; Kamp, I.; Waters, L. B. F. M.; Woitke, P.; Thi, W.-F.; Rab, Ch.; Aresu, G.; Spaans, M.

    2017-05-01

    The physical properties of brown dwarf discs, in terms of their shapes and sizes, are still largely unexplored by observations. ALMA has by far the best capabilities to observe these discs in sub-mm CO lines and dust continuum, while also spatially resolving some discs. To what extent brown dwarf discs are similar to scaled-down T Tauri discs is currently unknown, and this work is a step towards establishing a relationship through the eventual modelling of future observations. We use observations of the brown dwarf disc ρ Oph 102 to infer a fiducial model around which we build a small grid of brown dwarf disc models, in order to model the CO, HCN, and HCO+ line fluxes and the chemistry which drives their abundances. These are the first brown dwarf models to be published which relate detailed, 2D radiation thermochemical disc models to observational data. We predict that moderately extended ALMA antenna configurations will spatially resolve CO line emission around brown dwarf discs, and that HCN and HCO+ will be detectable in integrated flux, following our conclusion that the flux ratios of these molecules to CO emission are comparable to that of T Tauri discs. These molecules have not yet been observed in sub-mm wavelengths in a brown dwarf disc, yet they are crucial tracers of the warm surface-layer gas and of ionization in the outer parts of the disc. We present the prediction that if the physical and chemical processes in brown dwarf discs are similar to those that occur in T Tauri discs - as our models suggest - then the same diagnostics that are used for T Tauri discs can be used for brown dwarf discs (such as HCN and HCO+ lines that have not yet been observed in the sub-mm), and that these lines should be observable with ALMA. Through future observations, either confirmation (or refutation) of these ideas about brown dwarf disc chemistry will have strong implications for our understanding of disc chemistry, structure, and subsequent planet formation in brown

  14. Problems and pitfalls in a clinical research data management system.

    PubMed

    Brower, R W; ten Katen, H J; Meester, G T

    1984-01-01

    The problems and pitfalls encountered in the computerized data bank for the Netherlands Coronary Surgery (NCS) study are reviewed. This study involved 848 patients seen before coronary artery surgery and at 1 and 3 yr after surgery. Nineteen data forms were used resulting in maximally 1142 variables per patient. The importance of quality control is emphasized as well as the efficient transfer of information from data bank to statistical processing.

  15. Using demographic data to better interpret pitfall trap catches

    PubMed Central

    Matalin, Andrey V.; Makarov, Kirill V.

    2011-01-01

    Abstract The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia), 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered “residential”. In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered “transit”. Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a “labile” component in ground beetles communities, as opposed to a “stable” component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local populations and

  16. Common pitfalls in statistical analysis: Odds versus risk

    PubMed Central

    Ranganathan, Priya; Aggarwal, Rakesh; Pramesh, C. S.

    2015-01-01

    In biomedical research, we are often interested in quantifying the relationship between an exposure and an outcome. “Odds” and “Risk” are the most common terms which are used as measures of association between variables. In this article, which is the fourth in the series of common pitfalls in statistical analysis, we explain the meaning of risk and odds and the difference between the two. PMID:26623395

  17. Off-pump coronary artery bypass: techniques, pitfalls, and results.

    PubMed

    Hoff, Steven J

    2009-01-01

    In an attempt to advance the surgical treatment of coronary artery disease, surgeons sought a way to offer the proven benefits of coronary revascularization and avoid the side effects of cardiopulmonary bypass by performing revascularization in the beating heart (off-pump coronary artery bypass). This review will describe the development and refinement of the technique, pitfalls to its widespread adoption, and an up-to-date assessment of current results.

  18. Nurse practitioner private practice: three legal pitfalls to avoid.

    PubMed

    Buppert, C

    1996-04-01

    Private practice is now a viable option for nurse practitioners. NPs who open their own practice will be wise if they anticipate, consider, and act to prevent certain potential legal problems. Awareness and avoidance of these problems--risk avoidance--is the legal equivalent of preventive medicine. This article gives NPs an attorney's perspective on setting up a practice and some of the legal pitfalls to avoid.

  19. MRI Evaluation of the Urothelial Tract: Pitfalls and Solutions.

    PubMed

    Chung, Andrew D; Schieda, Nicola; Shanbhogue, Alampady Krishna; Dilauro, Marc; Rosenkrantz, Andrew B; Siegelman, Evan S

    2016-12-01

    MR urography (MRU) can be an alternative to CT urography (CTU) for imaging of the kidneys, urinary bladder, and collecting systems. MRU can be a challenging examination to perform and interpret, which may result in technical and interpretive errors being made. This article highlights the pitfalls associated with MRU and discusses how to recognize and avoid them. When performed properly, MRU may provide imaging quality generally comparable to that of CTU, and it enables comprehensive evaluation of the entire urinary tract.

  20. Artificial Discs for Lumbar and Cervical Degenerative Disc Disease –Update

    PubMed Central

    2006-01-01

    Executive Summary Objective To assess the safety and efficacy of artificial disc replacement (ADR) technology for degenerative disc disease (DDD). Clinical Need Degenerative disc disease is the term used to describe the deterioration of 1 or more intervertebral discs of the spine. The prevalence of DDD is roughly described in proportion to age such that 40% of people aged 40 years have DDD, increasing to 80% among those aged 80 years or older. Low back pain is a common symptom of lumbar DDD; neck and arm pain are common symptoms of cervical DDD. Nonsurgical treatments can be used to relieve pain and minimize disability associated with DDD. However, it is estimated that about 10% to 20% of people with lumbar DDD and up to 30% with cervical DDD will be unresponsive to nonsurgical treatments. In these cases, surgical treatment is considered. Spinal fusion (arthrodesis) is the process of fusing or joining 2 bones and is considered the surgical gold standard for DDD. Artificial disc replacement is the replacement of the degenerated intervertebral disc with an artificial disc in people with DDD of the lumbar or cervical spine that has been unresponsive to nonsurgical treatments for at least 6 months. Unlike spinal fusion, ADR preserves movement of the spine, which is thought to reduce or prevent the development of adjacent segment degeneration. Additionally, a bone graft is not required for ADR, and this alleviates complications, including bone graft donor site pain and pseudoarthrosis. It is estimated that about 5% of patients who require surgery for DDD will be candidates for ADR. Review Strategy The Medical Advisory Secretariat conducted a computerized search of the literature published between 2003 and September 2005 to answer the following questions: What is the effectiveness of ADR in people with DDD of the lumbar or cervical regions of the spine compared with spinal fusion surgery? Does an artificial disc reduce the incidence of adjacent segment degeneration (ASD

  1. Artificial discs for lumbar and cervical degenerative disc disease -update: an evidence-based analysis.

    PubMed

    2006-01-01

    To assess the safety and efficacy of artificial disc replacement (ADR) technology for degenerative disc disease (DDD). Degenerative disc disease is the term used to describe the deterioration of 1 or more intervertebral discs of the spine. The prevalence of DDD is roughly described in proportion to age such that 40% of people aged 40 years have DDD, increasing to 80% among those aged 80 years or older. Low back pain is a common symptom of lumbar DDD; neck and arm pain are common symptoms of cervical DDD. Nonsurgical treatments can be used to relieve pain and minimize disability associated with DDD. However, it is estimated that about 10% to 20% of people with lumbar DDD and up to 30% with cervical DDD will be unresponsive to nonsurgical treatments. In these cases, surgical treatment is considered. Spinal fusion (arthrodesis) is the process of fusing or joining 2 bones and is considered the surgical gold standard for DDD. Artificial disc replacement is the replacement of the degenerated intervertebral disc with an artificial disc in people with DDD of the lumbar or cervical spine that has been unresponsive to nonsurgical treatments for at least 6 months. Unlike spinal fusion, ADR preserves movement of the spine, which is thought to reduce or prevent the development of adjacent segment degeneration. Additionally, a bone graft is not required for ADR, and this alleviates complications, including bone graft donor site pain and pseudoarthrosis. It is estimated that about 5% of patients who require surgery for DDD will be candidates for ADR. The Medical Advisory Secretariat conducted a computerized search of the literature published between 2003 and September 2005 to answer the following questions: What is the effectiveness of ADR in people with DDD of the lumbar or cervical regions of the spine compared with spinal fusion surgery?Does an artificial disc reduce the incidence of adjacent segment degeneration (ASD) compared with spinal fusion?What is the rate of major

  2. Intervertebral disc repair by autologous mesenchymal bone marrow cells: a pilot study.

    PubMed

    Orozco, Lluis; Soler, Robert; Morera, Carles; Alberca, Mercedes; Sánchez, Ana; García-Sancho, Javier

    2011-10-15

    Degenerative disc disease may cause severe low-back pain, a large public health problem with significant economic and life quality impact. Chronic cases often require surgery, which may lead to biomechanical problems and accelerated degeneration of the adjacent segments. Cell-based therapies may circumvent these problems and have exhibited encouraging results in vitro and in animal studies. We designed a pilot study to assess feasibility and safety and to obtain early indications on efficacy of treatment with mesenchymal stem cells (MSC) in humans. Ten patients with chronic back pain diagnosed with lumbar disc degeneration with intact annulus fibrosus were treated with autologous expanded bone marrow MSC injected into the nucleus pulposus area. Clinical evolution was followed for 1 year and included evaluation of back pain, disability, and quality of life. Magnetic resonance imaging measurements of disc height and fluid content were also performed. Feasibility and safety were confirmed and strong indications of clinical efficacy identified. Patients exhibited rapid improvement of pain and disability (85% of maximum in 3 months) that approached 71% of optimal efficacy. This outcome compares favorably with the results of other procedures such as spinal fusion or total disc replacement. Although disc height was not recovered, water content was significantly elevated at 12 months. MSC therapy may be a valid alternative treatment for chronic back pain caused by degenerative disc disease. Advantages over current gold standards include simpler and more conservative intervention without surgery, preservation of normal biomechanics, and same or better pain relief.

  3. The role of cryopreservation in the biomechanical properties of the intervertebral disc.

    PubMed

    Lam, S K L; Chan, S C W; Leung, V Y L; Lu, W W; Cheung, K M C; Luk, K D K

    2011-12-17

    Implantation of intervertebral disc (IVD) allograft or tissue engineered disc constructs in the spine has emerged as an alternative to artificial disc replacement for the treatment of severe degenerative disc disease (DDD). Establishment of a bank of cryopreserved IVD allografts enables size matching and facilitates logistics for effective clinical management. However, the biomechanical properties of cryopreserved IVDs have not been previously reported. This study aimed to assess if cryopreservation with different concentrations of cryopreservant agents (CPA) would affect the dynamic viscoelastic properties of the IVD. Whole porcine lumbar IVDs (n = 40) were harvested and processed using various concentrations of CPA, 0 % CPA, 10 % CPA and 20 % CPA. The discs were cryopreserved using a stepwise freezing protocol and stored in liquid nitrogen. After four weeks of storage, the cryopreserved IVDs were quickly thawed at 37 °C for dynamic viscoelastic testing. The apparent modulus, elastic modulus (G'), viscous modulus (G") and loss modulus (G"/G') were calculated and compared to a fresh control group. Cryopreserved IVD without cryopreservants was significantly stiffer than the control. In the dynamic viscoelastic testing, cryopreservation with the use of CPA was able to preserve both G' and G" of an IVD. No significant differences were found between fresh IVD and IVD cryopreserved with 10 % CPA or 20 % CPA. This study demonstrated that CPAs at an optimal concentration could preserve the mechanical properties of the IVD allograft and can provide further credence for the application of long-term storage of IVD allografts for disc transplantation or tissue engineered construct applications.

  4. Proto-planetary disc evolution and dispersal

    NASA Astrophysics Data System (ADS)

    Rosotti, Giovanni Pietro

    2015-05-01

    Planets form from gas and dust discs in orbit around young stars. The timescale for planet formation is constrained by the lifetime of these discs. The properties of the formed planetary systems depend thus on the evolution and final dispersal of the discs, which is the main topic of this thesis. Observations reveal the existence of a class of discs called "transitional", which lack dust in their inner regions. They are thought to be the last stage before the complete disc dispersal, and hence they may provide the key to understanding the mechanisms behind disc evolution. X-ray photoevaporation and planet formation have been studied as possible physical mechanisms responsible for the final dispersal of discs. However up to now, these two phenomena have been studied separately, neglecting any possible feedback or interaction. In this thesis we have investigated what is the interplay between these two processes. We show that the presence of a giant planet in a photo-evaporating disc can significantly shorten its lifetime, by cutting the inner regions from the mass reservoir in the exterior of the disc. This mechanism produces transition discs that for a given mass accretion rate have larger holes than in models considering only X-ray photo-evaporation, constituting a possible route to the formation of accreting transition discs with large holes. These discs are found in observations and still constitute a puzzle for the theory. Inclusion of the phenomenon called "thermal sweeping", a violent instability that can destroy a whole disc in as little as 10 4 years, shows that the outer disc left can be very short-lived (depending on the X-ray luminosity of the star), possibly explaining why very few non accreting transition discs are observed. However the mechanism does not seem to be efficient enough to reconcile with observations. In this thesis we also show that X-ray photo-evaporation naturally explains the observed correlation between stellar masses and accretion

  5. Disc erosion in Models 103 and 104 of Beall mitral valve prostheses

    PubMed Central

    Gómez, Ricardo; Verduras, María José; Lopez-Quintana, Alfonso; Riera, Luis; Zerolo, Ignacio; Martinez-Bordiu, Cristóbal

    1981-01-01

    Three cases of severe disc variance and erosion of the Teflon-disc Beall mitral valve prosthesis (Models 103 and 104) are reported. In two patients, the Beall mitral valves were excised and replaced with two Björk-Shiley mitral valves. The remaining patient did not survive, and at autopsy, the lens was found at the aortic bifurcation level. Because of this potentially lethal complication, careful follow-up of patients with Beall mitral valve prostheses (Models 103 and 104) is recommended. Images PMID:15216211

  6. Disc erosion in Models 103 and 104 of Beall mitral valve prostheses.

    PubMed

    Gómez, Ricardo; Verduras, María José; Lopez-Quintana, Alfonso; Riera, Luis; Zerolo, Ignacio; Martinez-Bordiu, Cristóbal

    1981-06-01

    Three cases of severe disc variance and erosion of the Teflon-disc Beall mitral valve prosthesis (Models 103 and 104) are reported. In two patients, the Beall mitral valves were excised and replaced with two Björk-Shiley mitral valves. The remaining patient did not survive, and at autopsy, the lens was found at the aortic bifurcation level. Because of this potentially lethal complication, careful follow-up of patients with Beall mitral valve prostheses (Models 103 and 104) is recommended.

  7. Sensitivity of notochordal disc cells to mechanical loading: an experimental animal study

    PubMed Central

    Guehring, Thorsten; Nerlich, Andreas; Kroeber, Markus; Richter, Wiltrud

    2009-01-01

    The immature disc nucleus pulposus (NP) consists of notochordal cells (NCs). With maturation NCs disappear in humans, to be replaced by chondrocyte-like mature NP cells (MNPCs); this change in cell phenotype coincidences with early signs of disc degeneration. The reasons for NC disappearance are important to understand disc degeneration, but remain unknown, yet. This study investigated, whether loading induced a change from a notochordal nucleus phenotype to a chondrocyte-like one. An in vivo disc compression model with fixateur externe was used in 36 mature rabbits. Discs were compressed for different time periods (1, 28, 56 days), and compared with uncompressed control discs (56 days without treatment), and discs with sham compression (28 days). Nucleus cell phenotype was determined by histology and immunohistochemistry. NCs, but not MNPCs highly expressed bone-morphogenetic-protein 2 and cytokeratin 8, thus NC and MNPC numbers could be determined. A histologic score was used to detect structural endplate changes after compression (28 days). Control and sham compressed discs contained around 70% NCs and 30% MNPCs, to be decreased to <10% NCs after 28–56 days of loading. NC density fell sharply by >50% after 28–56 days of compression (P < 0.05 vs. controls). Signs of decreased endplate cellularity and increased endplate sclerosis and fibrosis were found after loading. These experiments show that NCs were less resistant to mechanical stress than MNPCs suggesting that increased intradiscal pressures after loading, and limited nutrition through structurally altered endplates could instigate the disappearance of NCs. PMID:19936803

  8. Magnetic field dragging in accretion discs

    NASA Astrophysics Data System (ADS)

    de Guiran, R.; Ferreira, J.

    2010-12-01

    Accretion discs are composed of ionized gas in motion around a central object. Sometimes, the disc is the source of powerful bipolar jets along its rotation axis. Theoretical models invoke the existence of a bipolar magnetic field crossing the disc and require two conditions to produce powerful jets: field lines need to be bent enough at the disc surface and the magnetic field needs to be close to equipartition. The work of Petrucci et al (2008) on the variability of X-ray binaries supposes that transitions between pure accretion phases and accretion-ejection phases are due to some variations of the disc magnetization. This rises the problem of the magnetic field dragging in accretion discs. We revisit the method developed by Lubow et al (1994) by including momentum and mass conservation equations in a time-dependent 1D MHD code.

  9. [Polish nomenclature of lumbar disc disease].

    PubMed

    Radło, Paweł; Smetkowski, Andrzej; Tesiorowski, Maciej

    2014-01-01

    Lumbar disc herniation is one of the most common damage of musculoskeletal system. The incidence of pain of lumbosacral spine is estimated approximately on 60-90% in general population, whereas the incidence of disc herniation in patients experiencing low back pain is about 91%. Despite the high incidence and uncomplicated pathogenesis of disc disease there is a problem with the nomenclature. In the vast majority of cases, the naming confusion stems from ignorance of the etiology of low back pain. Different terminologies: morphological, topographical, Radiological and Clinical are used interchangeably. In addition, diagnosis is presented in a variety of languages: Polish, English and Latin. Moreover, the medical and traditional language are used alternately. The authors found in Polish literature more, than 20 terms to describe lumbar disc herniation. All of these terms in the meaning of the authors are used to determine one pathology--mechanical damage to the intervertebral disc and moving the disc material beyond the anatomical area.

  10. Close-packing of growing discs

    SciTech Connect

    Bursill, L.A.; Xudong, F. . School of Physics)

    1988-12-01

    Spiral lattices are derived by allowing growing discs to aggregate under a close-packing rule. Both Fibonacci and Lucas numbers of visible spirals arise naturally, dependent only on the choice of growth centre. Both the rate of convergence towards an ideal spiral, and chirality, are determined by the initial placement of the first few discs (initial conditions). Thus the appearance of spiral packings is no more or less mysterious than the appearance of hexagonal packed arrays of equal discs.

  11. Factors that influence recurrent lumbar disc herniation.

    PubMed

    Yaman, M E; Kazancı, A; Yaman, N D; Baş, F; Ayberk, G

    2017-06-01

    The most common cause of poor outcome following lumbar disc surgery is recurrent herniation. Recurrence has been noted in 5% to 15% of patients with surgically treated primary lumbar disc herniation. There have been many studies designed to determine the risk factors for recurrent lumbar disc herniation. In this study, we retrospectively analysed the influence of disc degeneration, endplate changes, surgical technique, and patient's clinical characteristics on recurrent lumbar disc herniation. Patients who underwent primary single-level L4-L5 lumbar discectomy and who were reoperated on for recurrent L4-L5 disc herniation were retrospectively reviewed. All these operations were performed between August 2004 and September 2009 at the Neurosurgery Department of Ataturk Education and Research Hospital in Ankara, Turkey. During the study period, 126 patients were reviewed, with 101 patients underwent primary single-level L4-L5 lumbar discectomy and 25 patients were reoperated on for recurrent L4-L5 disc herniation. Preoperative higher intervertebral disc height (P<0.001) and higher body mass index (P=0.042) might be risk factors for recurrence. Modic endplate changes were statistically significantly greater in the recurrent group than in the non-recurrent group (P=0.032). Our study suggests that patients who had recurrent lumbar disc herniation had preoperative higher disc height and higher body mass index. Modic endplate changes had a higher tendency for recurrence of lumbar disc herniation. Well-planned and well-conducted large-scale prospective cohort studies are needed to confirm this and enable convenient treatment modalities to prevent recurrent disc pathology.

  12. Disc repositioning: does it really work?

    PubMed

    Gonçalves, João Roberto; Cassano, Daniel Serra; Rezende, Luciano; Wolford, Larry M

    2015-02-01

    Although limited, there is evidence to support the assumption that temporomandibular joint (TMJ) articular disc repositioning indeed works; to date, there is no evidence that TMJ articular disc repositioning does not work. Despite the controversy among professionals in private practice and academia, TMJ articular disc repositioning is a procedure based on (still limited) evidence; the opposition is based solely on clinical preference and influenced by the ability to perform it or not. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. The quiescent phase of galactic disc growth

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; Binney, James; Schönrich, Ralph

    2016-07-01

    We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs, we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age-velocity dispersion relation of the solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral-induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models, the outward-migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.

  14. Accretion Discs Show Their True Colours

    NASA Astrophysics Data System (ADS)

    2008-07-01

    Quasars are the brilliant cores of remote galaxies, at the hearts of which lie supermassive black holes that can generate enough power to outshine the Sun a trillion times. These mighty power sources are fuelled by interstellar gas, thought to be sucked into the hole from a surrounding 'accretion disc'. A paper in this week's issue of the journal Nature, partly based on observations collected with ESO's Very Large Telescope, verifies a long-standing prediction about the intensely luminous radiation emitted by these accretion discs. Uncovering the disc ESO PR Photo 21/08 Uncovering the inner disc "Astronomers were puzzled by the fact that the best models of these discs couldn't quite be reconciled with some of the observations, in particular, with the fact that these discs did not appear as blue as they should be," explains lead-author Makoto Kishimoto. Such a discrepancy could be the signal that there was something very wrong with the models. With his colleagues, he investigated this discrepancy by studying the polarised light from six quasars. This enabled them to demonstrate that the disc spectrum is as blue as predicted. "The crucial observational difficulty here has been that the disc is surrounded by a much larger torus containing hot dust, whose light partly outshines that of the disc," says Kishimoto. "Because the light coming from the disc is scattered in the disc vicinity and thus polarised, by observing only polarised light from the quasars, one can uncover the buried light from the disc." In a similar way that a fisherman would wear polarised sunglasses to help get rid of the glare from the water surface and allow him to see more clearly under the water, the filter on the telescope allowed the astronomers to see beyond surrounding clouds of dust and gas to the blue colour of the disc in infrared light. The observations were done with the FORS and ISAAC instruments on one of the 8.2-m Unit Telescopes of ESO's Very Large Telescope, located in the Atacama

  15. State-of-the-art 3DCT angiography assessment of lower extremity trauma: typical findings, pearls, and pitfalls.

    PubMed

    Fritz, Jan; Efron, David T; Fishman, Elliot K

    2013-06-01

    Multi-detector computed tomography angiography (MDCTA) of the lower extremities is an integral part of the decision-making process of lower extremity trauma. MDCTA can be integrated into multiphasic whole-body trauma MDCT and has replaced the traditional gold standard of catheter-based angiography as the preferred technique for the initial assessment of lower extremity trauma in many institutions worldwide. Advances in MDCT technology enable high speed simultaneous evaluation of both complete lower extremities, rapid image reconstruction, and advanced image visualization for the noninvasive and accurate diagnosis of vascular, including hematoma, active extravasation, vasospasm, stenosis, external compression, occlusion, intimal injury and dissection, arteriovenous fistulas, and pseudoaneurysm formation. In this exhibit, we outline the role of MDCTA in the management of lower extremity trauma, review current MDCT protocols and the practical use of advanced visualization techniques, and illustrate typical MDCTA findings, pearls, and pitfalls, which help to accurately characterize vascular injury and guide management.

  16. Grain charging in protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Ilgner, M.

    2012-02-01

    Context. Recent work identified a growth barrier for dust coagulation that originates in the electric repulsion between colliding particles. Depending on its charge state, dust material may have the potential to control key processes towards planet formation such as magnetohydrodynamic (MHD) turbulence and grain growth, which are coupled in a two-way process. Aims: We quantify the grain charging at different stages of disc evolution and differentiate between two very extreme cases: compact spherical grains and aggregates with fractal dimension Df = 2. Methods: Applying a simple chemical network that accounts for collisional charging of grains, we provide a semi-analytical solution. This allowed us to calculate the equilibrium population of grain charges and the ionisation fraction efficiently. The grain charging was evaluated for different dynamical environments ranging from static to non-stationary disc configurations. Results: The results show that the adsorption/desorption of neutral gas-phase heavy metals, such as magnesium, effects the charging state of grains. The greater the difference between the thermal velocities of the metal and the dominant molecular ion, the greater the change in the mean grain charge. Agglomerates have more negative excess charge on average than compact spherical particles of the same mass. The rise in the mean grain charge is proportional to N1/6 in the ion-dust limit. We find that grain charging in a non-stationary disc environment is expected to lead to similar results. Conclusions: The results indicate that the dust growth and settling in regions where the dust growth is limited by the so-called "electro-static barrier" do not prevent the dust material from remaining the dominant charge carrier.

  17. Circumplanetary discs around young giant planets: a comparison between core-accretion and disc instability

    NASA Astrophysics Data System (ADS)

    Szulágyi, J.; Mayer, L.; Quinn, T.

    2017-01-01

    Circumplanetary discs can be found around forming giant planets, regardless of whether core accretion or gravitational instability built the planet. We carried out state-of-the-art hydrodynamical simulations of the circumplanetary discs for both formation scenarios, using as similar initial conditions as possible to unveil possible intrinsic differences in the circumplanetary disc mass and temperature between the two formation mechanisms. We found that the circumplanetary discs' mass linearly scales with the circumstellar disc mass. Therefore, in an equally massive protoplanetary disc, the circumplanetary discs formed in the disc instability model can be only a factor of 8 more massive than their core-accretion counterparts. On the other hand, the bulk circumplanetary disc temperature differs by more than an order of magnitude between the two cases. The subdiscs around planets formed by gravitational instability have a characteristic temperature below 100 K, while the core-accretion circumplanetary discs are hot, with temperatures even greater than 1000 K when embedded in massive, optically thick protoplanetary discs. We explain how this difference can be understood as the natural result of the different formation mechanisms. We argue that the different temperatures should persist up to the point when a full-fledged gas giant forms via disc instability; hence, our result provides a convenient criterion for observations to distinguish between the two main formation scenarios by measuring the bulk temperature in the planet vicinity.

  18. Variables affecting disc size in the lumbar spine of rabbits: anesthesia, paralysis, and disc injury.

    PubMed

    Neufeld, J H; Machado, T; Margolin, L

    1991-01-01

    Methods have been developed that permit repetitive radiographic measurement of the lumbar intervertebral disc space in a rostral-caudal direction (width) in the anesthetized laboratory rabbit. Using isolated control discs and injured discs in which narrowing has been induced for chronic and acute periods, the widths of the lumbar intervertebral disc spaces determined ratio-graphically correlate with widths determined histologically (p less than 0.000, r = 0.75). Both an increase (widening) and a decrease (narrowing) in disc width were observed using radiography after different experimental treatments. Anesthesia and lower-body paralysis (an experimentally induced inability to bear weight on and to perceive a pinch stimulus in hind limbs) caused widening of the discs: anesthesia causing a general widening throughout the lumbar spine and lower-body paralysis causing a specific widening low in the lumbar spine. Both disc injection and piercing the disc with needles to recover nucleus pulposus material caused narrowing of the discs. Acridine-orange injection induced a narrowing accompanied by osteophytosis. Experimentally induced narrowing at L4-5 (the result of injury to the disc) resulted in narrowing also at L2-3. These findings are consistent with the hypothesis that in vivo disc-width size in the young rabbit depends on both the quantity of nucleus pulposus material and the force-generating activities of the adjacent spinal muscles, and that disc injury at one level stimulates narrowing at other levels.

  19. [Standardized terminology for disc disease].

    PubMed

    Sánchez Pérez, M; Gil Sierra, A; Sánchez Martín, A; Gallego Gómez, P; Pereira Boo, D

    2012-01-01

    This article reviews the terminology used to describe morphological alterations in the intervertebral discs. Radiologists must be able to communicate information about the type, location, and severity of these alterations to medical and surgical clinicians. It is crucial to use simple, standard, and unified terminology to ensure comprehension not only among radiologists but also with professionals from the different specialties for whom the radiology reports are written (fundamentally traumatologists and neurosurgeons). This terminology will help ensure a more accurate diagnosis and better patient management.

  20. A new cervical artificial disc prosthesis based on physiological curvature of end plate: a finite element analysis.

    PubMed

    Yu, Cheng-Cheng; Liu, Peng; Huang, Da-Geng; Jiang, Yong-Hong; Feng, Hang; Hao, Ding-Jun

    2016-11-01

    The study aimed to build a new cervical artificial disc C3-C7 segment prosthesis, and perform a biomechanical comparison between the new prosthesis and the Prestige LP prosthesis using a three-dimensional non-linear finite element (FE) model. The study compared the biomechanical differences between the new cervical artificial disc prosthesis based on the physiological curvature of the end plate and the Prestige LP prosthesis after artificial disc replacement. There has been no prior research on artificial disc prostheses based on the physiological curvature of the end plate; studies of biomechanical changes after cervical disc arthroplasty (CDR) are few. An FE model of the C3-C7 segments was developed and validated. A new cervical artificial disc prosthesis based on the physiological curvature of the end plate and the Prestige LP prosthesis were integrated at the C5-C6 segment into the validated FE model. All models were subjected to a follower load of 73.6 N and a 1 Nm in flexion-extension, lateral bending, and axial torsion. The segmental range of motion (ROM) and stress on the prostheses were analyzed. The ROM in most segments after CDR with new cervical artificial disc prosthesis was more similar to that of the normal cervical spine than the Prestige LP prosthesis. However, there was no significant difference between the two prostheses. The stress on the new artificial disc was significantly less than that in the Prestige LP prosthesis. There was no significant difference in ROM in all segments after CDR for the two prostheses. The stress on the new cervical artificial disc prosthesis based on the physiological curvature of the end plate was significantly less than that in the Prestige LP prosthesis. The new artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface stress on the end plate, which may be one of the causes of prosthesis subsidence. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Qualifying stem cell sources: how to overcome potential pitfalls in regenerative medicine?

    PubMed

    Reinke, Simon; Dienelt, Anke; Blankenstein, Antje; Duda, Georg N; Geissler, Sven

    2016-01-01

    Regenerative medicine aims to replace lost cells and to restore damaged tissues and organs by either tissue-engineering approaches or stimulation of endogenous processes. Due to their biological properties, stem cells promise to be an effective source for such strategies. Especially adult multipotent stem cells (ASCs) are believed to be applicable in a broad range of therapies for the treatment of multifactorial diseases or age-related degeneration, although the molecular and cellular mechanisms underlying their regenerative function are often hardly described. Moreover, in some demanding clinical situations their efficiency remains limited. Thus, a basic understanding of ASCs regenerative function, their complex interplay with their microenvironment and how compromising conditions interfere with their efficiency is mandatory for any regenerative strategy. Concerning this matter, the impact of patient-specific constraints are often underestimated in research projects and their influence on the study results disregarded. Thus, researchers are urgently depending on well-characterized tissue samples or cells that are connected with corresponding donor information, such as secondary diseases, medication. Here, we outline principle pitfalls during experimental studies using human samples, and describe a potential strategy to overcome these challenges by establishing a core unit for cell and tissue harvesting. This facility aims to bridge the gap between clinic and research laboratories by the provision of a direct link to the clinical operating theatres. Such a strategy clearly supports basic and clinical research in the conduct of their studies and supplies highly characterized human samples together with the corresponding donor information.

  2. Single-pool exponential decomposition models: potential pitfalls in their use in ecological studies.

    PubMed

    Adair, E Carol; Hobbie, Sarah E; Hobbie, Russell K

    2010-04-01

    The importance of litter decomposition to carbon and nutrient cycling has motivated substantial research. Commonly, researchers fit a single-pool negative exponential model to data to estimate a decomposition rate (k). We review recent decomposition research, use data simulations, and analyze real data to show that this practice has several potential pitfalls. Specifically, two common decisions regarding model form (how to model initial mass) and data transformation (log-transformed vs. untransformed data) can lead to erroneous estimates of k. Allowing initial mass to differ from its true, measured value resulted in substantial over- or underestimation of k. Log-transforming data to estimate k using linear regression led to inaccurate estimates unless errors were lognormally distributed, while nonlinear regression of untransformed data accurately estimated k regardless of error structure. Therefore, we recommend fixing initial mass at the measured value and estimating k with nonlinear regression (untransformed data) unless errors are demonstrably lognormal. If data are log-transformed for linear regression, zero values should be treated as missing data; replacing zero values with an arbitrarily small value yielded poor k estimates. These recommendations will lead to more accurate k estimates and allow cross-study comparison of k values, increasing understanding of this important ecosystem process.

  3. Hair analysis in forensic toxicology: an updated review with a special focus on pitfalls.

    PubMed

    Kintz, Pascal

    2017-09-29

    The detection and drugs in hair analysis has progressively emerged as a consequence of the enhanced sensitivity of analytical techniques used in forensic toxicology; a greater advantage in using this matrix respect to classical ones (i.e. urine and blood) is an easier and non-invasive sample collection, even when the careful supervision of law enforcement officers is required to avoid the risk that the sample may be adulterated or replaced. Moreover, according to the length of the hair, the history of drug exposure can be retrospectively monitored from few weeks up to months or years since sample collection. Through a detailed revision of the existent literature, this manuscript provides information on the proper sample collection, preparation and analysis, as well as pitfalls in forensic hair analysis, and summarizes the wide range of application of this technology, including excessive alcohol drinking, doping, child abuse, and offences linked to drug use. Verification of history of psychotropic drugs, alcohol and doping agents use by hair analysis, hair testing for license regranting and drug facilitated crimes, testing for drugs in hair of children have been reviewed together with recent trends in hair contamination and possibility to disclose use of new psychoactive substances by hair analysis. Hair analysis in forensic toxicology has been quickly emerged and improved in recent years; a deeper knowledge of advantages and limitations of this unique matrix is necessary for a better use in forensic caseworks. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Evaluation of the robotic approach concerning pitfalls in rectal surgery.

    PubMed

    Baukloh, J K; Reeh, M; Spinoglio, G; Corratti, A; Bartolini, I; Mirasolo, V M; Priora, F; Izbicki, J R; Gomez Fleitas, M; Gomez Ruiz, M; Perez, D R

    2017-07-01

    The feasibility and advantages of robotic rectal surgery (RRS) in comparison to conventional open or laparoscopic rectal resections have been postulated in several reports. But well-known challenges and pitfalls of minimal invasive rectal surgery have not been evaluated by a prospective, multicenter setting so far. Aim of this study was to analyze the perioperative outcome of patients following RRS especially in regard to the pitfalls such as obesity, male patients and low tumors by a European multicenter setting. This prospective study included 348 patients undergoing robotic surgery due to rectal cancer in six major European centers. Clinicopathological parameters, morbidity, perioperative recovery and short-term outcome were analyzed. A total of 283 restorative surgeries and 65 abdominoperineal resections were carried out. The conversion rate was 4.3%, mean blood loss was 191 ml, and mean operative time was 315 min. Postoperative complications with a Clavien-Dindo score >2 were observed in 13.5%. Obesity and low rectal tumors showed no significant higher rates of major complications or impaired oncological parameters. Male patients had significant higher rates of major complications and anastomotic leakage (p = 0.048 and p = 0.007, respectively). RRS is a promising tool for improvement of rectal resections. The well-known pitfalls of minimal-invasive rectal surgery like obesity and low tumors were sufficiently managed by RRS. However, RRS showed significantly higher rates of major complications and anastomotic leakage in male patients, which has to be evaluated by future randomized trials. Copyright © 2017 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

  5. Overview of subtalar arthrodesis techniques: options, pitfalls and solutions.

    PubMed

    Tuijthof, Gabriëlle J M; Beimers, Lijkele; Kerkhoffs, Gino M M J; Dankelman, Jenny; Dijk, C Niek van

    2010-09-01

    Subtalar arthrodesis (SA) is the preferred treatment for painful isolated subtalar disease. Although results are generally favourable, analysis of current operative techniques will help optimizing this treatment. The aim was to give an overview of SA-techniques and their pitfalls. Possible solutions were identified. A literature search was performed for papers that presented SA operative techniques. The general technique was divided into phases: surgical approach, cartilage removal, bone graft selection, hindfoot deformity correction and fixation. The published series were invariably retrospective reviews of small heterogenous groups of different hindfoot pathologies. The weighted outcome rate for SA was 85% (68-100%) performed in 766 feet and for SA requiring correction of malalignment 65% (36-96%) in 1001 feet. Non-union (weighted percentage 12%), malalignment (18%), and screw removal (17%) were the prevailing late complications. The following pitfalls were identified: 1) early complications related to the incisions made in open approaches, 2) insufficient cartilage removal, improper bone graft selection and fixation techniques, all possibly leading to non-union, 3) morbidity caused by bone graft harvesting and secondary screw removal, 4) under- or overcorrection of the hindfoot possibly due to improper intraoperative verification and 5) inadequate assessment of bony fusion. The review provides solutions to possibly overcome some pitfalls: 1) if applicable use an arthroscopic approach in combination with distraction devices and new burrs, 2) if possible use local bone graft or allografts, 3) use two screws for fixation to prevent rotational micromotion, and 4) improve assessment of operative outcome by application of appropriate assessment of bony fusion and alignment. The review provides practical suggestions to optimize SA-techniques. Copyright (c) 2009 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.

  6. Pattern reorganization occurs independently of cell division during Drosophila wing disc regeneration in situ.

    PubMed

    Díaz-García, Sandra; Baonza, Antonio

    2013-08-06

    One of the most intriguing problems in developmental biology is how an organism can replace missing organs or portions of its body after injury. This capacity, known as regeneration, is conserved across different phyla. The imaginal discs of Drosophila melanogaster provide a particularly well-characterized model for analyzing regeneration. We have developed a unique method to study organ regeneration under physiological conditions using the imaginal discs of Drosophila. Using this method, we revisited different aspects of organ regeneration. The results presented in this report suggest that during the initial stages of regeneration, different processes occur, including wound healing, a temporary loss of markers of cell-fate commitment, and pattern reorganization. We present evidence indicating that all of these processes occur even when cell division has been arrested. Our data also suggested that Wingless is not required during the early stages of disc regeneration.

  7. Pattern reorganization occurs independently of cell division during Drosophila wing disc regeneration in situ

    PubMed Central

    Díaz-García, Sandra; Baonza, Antonio

    2013-01-01

    One of the most intriguing problems in developmental biology is how an organism can replace missing organs or portions of its body after injury. This capacity, known as regeneration, is conserved across different phyla. The imaginal discs of Drosophila melanogaster provide a particularly well-characterized model for analyzing regeneration. We have developed a unique method to study organ regeneration under physiological conditions using the imaginal discs of Drosophila. Using this method, we revisited different aspects of organ regeneration. The results presented in this report suggest that during the initial stages of regeneration, different processes occur, including wound healing, a temporary loss of markers of cell-fate commitment, and pattern reorganization. We present evidence indicating that all of these processes occur even when cell division has been arrested. Our data also suggested that Wingless is not required during the early stages of disc regeneration. PMID:23878228

  8. Quantitative Pfirrmann Disc Degeneration Grading System to Overcome the Limitation of Pfirrmann Disc Degeneration Grade.

    PubMed

    Rim, Dae Cheol

    2016-03-01

    Pfirrmann disc degeneration grade is one of morphologic disc degeneration grading system and it was reliable on routine T2-weighted magnetic resonance (MR) images. The purpose of this study was to evaluate the agreement of Pfirrmann disc degeneration grade, and check the alternative technique of disc degeneration grading system. Fifteen volunteers (4 medical doctors related to spinal disease, 2 medical doctors not related to spinal disease, 6 nurses in spinal hospital, and 3 para-medicines) were included in this study. Three different digitalized MR images were provided all volunteers, and they checked Pfirrmann disc degeneration grade of each disc levels after careful listening to explanation. Indeed, all volunteers checked the signal intensity of disc degeneration at the points of nucleus pulposus (NP), disc membrane, ligaments, fat, and air to modify the quantitative Pfirrmann disc degeneration grade. Total 225 grade results of Pfirrmann disc degeneration grade and 405 signal intensity results of quantitative Pfirrmann disc degeneration grade were analyzed. Average interobserver agreement was "moderate (mean±standard deviation, 0.575±0.251)" from poor to excellent. Completely agreed levels of Pfirrmann disc degeneration grade were only 4 levels (26.67%), and the disagreement levels were observed in 11 levels; two different grades in 8 levels (53.33%) and three different grades in 3 levels (20%). Quantitative Pfirrmann disc degeneration showed relatively cluster distribution with the interobserver deviations of 0.41-1.56 at the ratio of NP and disc membrane, and it showed relatively good cluster and distribution indicating that the proposed grading system has good discrimination ability. Pfirrmann disc degeneration grade showed the limitation of different interobserver results, but this limitation could be overcome by using quantitative techniques of MR signal intensity. Further evaluation is needed to access its advantage and reliabilities.

  9. Toxicology: pearls and pitfalls in the use of antidotes.

    PubMed

    Smollin, Craig G

    2010-02-01

    Although most poisonings require only supportive care, the emergency physician must recognize when the use of an antidote is required, and understand the risks and benefits of the treatment rendered. Although the more commonly instituted specific therapy in acute poisoning is the administration of intravenous fluids followed by the administration of oxygen, in certain circumstances prompt administration of a specific antidote may be required, and failure to identify these circumstances may lead to significant morbidity or mortality. This article describes select antidotes, and discusses their indications and potential pitfalls.

  10. The seven common pitfalls of customer service in hospitals.

    PubMed

    Domingo, Rene T

    2015-01-01

    Operating simultaneously like a repair shop, prison, and hotel, hospitals are prone to seven common pitfalls in customer service. Patient care is often fragmented, inscrutable, inflexible, insensitive, reactive, myopic, and unsafe. Hospitals are vying to be more high-tech, rather than high-touch even though staff engagement with patients rather than facilities and equipment strongly influence patient satisfaction. Unless processes, policies, and people are made customer-centered, the high quality of the hospital's human and hardware resources will not translate into high patient satisfaction and patient loyalty.

  11. Cultural Diversity in Nursing Education: Perils, Pitfalls, and Pearls

    PubMed Central

    Bednarz, Hedi; Schim, Stephanie; Doorenbos, Ardith

    2010-01-01

    Increasing diversity in the classroom challenges nursing educators to identify issues that complicate teaching (perils), analyze barriers for themselves and their students (pitfalls), and select new strategies for working with nontraditional students (pearls). This article identifies concerns arising from attitudes and values within nursing and common approaches to diversity education, and then discusses key issues in nursing education that relate to human nature, culture, faculty workload, and student demographics. Finally, some strategies are proposed for increasing the effectiveness of professional preparation with diverse students through a focus on culturally congruent education and development of faculty cultural competence. PMID:20143759

  12. Severe anemia owing to occult pulmonary hemorrhage: a diagnostic pitfall.

    PubMed

    Minkov, Milen; Kovacs, Julia; Wiesbauer, Peter; Dekan, Gerhard; Gadner, Helmut

    2006-07-01

    The purpose of this paper is to increase the awareness about pulmonary hemorrhage as a possible cause of microcytic hypochromic anemia and to delineate diagnostic difficulties and possible pitfalls. An instructive case of anemia of unclear origin referred to our institution for a hematologic workup is presented. Microcytic hypochromic anemia owing to repeated occult alveolar hemorrhages was the only clinical sign of idiopathic pulmonary hemosiderosis in this case. The laboratory finding constellation in such cases may be misleading and may lead to misinterpretation. Awareness about this condition among pediatricians and hematologists can optimize and accelerate the diagnostic process.

  13. Epidemiological designs for vaccine safety assessment: methods and pitfalls.

    PubMed

    Andrews, Nick

    2012-09-01

    Three commonly used designs for vaccine safety assessment post licensure are cohort, case-control and self-controlled case series. These methods are often used with routine health databases and immunisation registries. This paper considers the issues that may arise when designing an epidemiological study, such as understanding the vaccine safety question, case definition and finding, limitations of data sources, uncontrolled confounding, and pitfalls that apply to the individual designs. The example of MMR and autism, where all three designs have been used, is presented to help consider these issues. Copyright © 2011 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

  14. Cultural diversity in nursing education: perils, pitfalls, and pearls.

    PubMed

    Bednarz, Hedi; Schim, Stephanie; Doorenbos, Ardith

    2010-05-01

    Increasing diversity in the classroom challenges nursing educators to identify issues that complicate teaching (perils), analyze barriers for themselves and their students (pitfalls), and select new strategies for working with nontraditional students (pearls). This article identifies concerns arising from attitudes and values within nursing and common approaches to diversity education, and then discusses key issues in nursing education that relate to human nature, culture, faculty workload, and student demographics. Finally, some strategies are proposed for increasing the effectiveness of professional preparation with diverse students through a focus on culturally congruent education and development of faculty cultural competence.

  15. How group practices can avoid managed care contracting pitfalls.

    PubMed

    Gosfield, A G

    1999-07-01

    When negotiating contracts with managed care organizations, group practices should understand the potential pitfalls involved. The basic issues to be aware of are understanding the relative parties' negotiating positions, the business significance of fundamental terms, and the actual contract provisions. The most important clauses in contracts concern compensation and termination. Group practices should require that their contracts include clauses that provide the physicians with protection should utilization assumptions not be met. They also should be realistic about their ability to fulfill contract terms. In addition, contract terms should be clearly written, well-defined, and time-limited.

  16. Fluorescent proteins in cellular organelles: serious pitfalls and some solutions.

    PubMed

    Costantini, Lindsey M; Snapp, Erik Lee

    2013-11-01

    Fluorescent proteins (FPs) have been powerful tools for cell biologists for over 15 years. The large variety of FPs available rarely comes with an instruction manual or a warning label. The potential pitfalls of the use of FPs in cellular organelles represent a significant concern for investigators. FPs generally did not evolve in the often distinctive physicochemical environments of subcellular organelles. In organelles, FPs can misfold, go dark, and even distort organelle morphology. In this minireview, we describe the issues associated with FPs in organelles and provide solutions to enable investigators to better exploit FP technology in cells.

  17. Lost in Translation: Pitfalls in Deciphering Plant Alternative Splicing Transcripts

    PubMed Central

    Brown, John W.S.; Simpson, Craig G.; Marquez, Yamile; Gadd, Geoffrey M.; Barta, Andrea; Kalyna, Maria

    2015-01-01

    Transcript annotation in plant databases is incomplete and often inaccurate, leading to misinterpretation. As more and more RNA-seq data are generated, plant scientists need to be aware of potential pitfalls and understand the nature and impact of specific alternative splicing transcripts on protein production. A primary area of concern and the topic of this article is the (mis)annotation of open reading frames and premature termination codons. The basic message is that to adequately address expression and functions of transcript isoforms, it is necessary to be able to predict their fate in terms of whether protein isoforms are generated or specific transcripts are unproductive or degraded. PMID:26286536

  18. Principles and Pitfalls: a Guide to Death Certification

    PubMed Central

    Brooks, Erin G.; Reed, Kurt D.

    2015-01-01

    Death certificates serve the critical functions of providing documentation for legal/administrative purposes and vital statistics for epidemiologic/health policy purposes. In order to satisfy these functions, it is important that death certificates be filled out completely, accurately, and promptly. The high error rate in death certification has been documented in multiple prior studies, as has the effectiveness of educational training interventions at mitigating errors. The following guide to death certification is intended to illustrate some basic principles and common pitfalls in electronic death registration with the goal of improving death certification accuracy. PMID:26185270

  19. Pitfalls and Limitations of Radionuclide Hepatobiliary and Gastrointestinal System Imaging.

    PubMed

    Low, Chen Sheng; Ahmed, Haseeb; Notghi, Alp

    2015-11-01

    Radionuclide imaging for the hepatobiliary and gastrointestinal system covers a wide range of different indications and imaging techniques. This wide variety allows the different functional assessments of both systems. Therefore, the understanding of each technique and its indications is essential. Cholescintigraphy is a well-established method in the assessment of acute and chronic cholecystitis. It also has a role in the detection of biliary atresia. The assessment of gastrointestinal transit is also well-established in radionuclide imaging for functional investigation of the gastrointestinal tract. Furthermore, detection of acute gastrointestinal bleeding with radionuclide imaging is also standard practice. This article aims to review the pitfalls and limitations in all of these areas.

  20. Dropped gallstones: spectrum of imaging findings, complications and diagnostic pitfalls.

    PubMed

    Nayak, L; Menias, C O; Gayer, G

    2013-08-01

    Spillage of gallstones into the abdominal cavity, referred to as "dropped gallstones" (DGs), occurs commonly during laparoscopic cholecystectomy. The majority of these spilled stones remain clinically silent; however, if uncomplicated DGs are not correctly identified on subsequent imaging, they may mimic peritoneal implants and cause unduly concern. A small percentage of DGs cause complications, including abscess and fistula formation. Recognising the DG within the abscess is critical for definitive treatment. This pictorial review illustrates the imaging appearances and complications of DGs on CT, MRI and ultrasound and emphasises pitfalls in diagnosis.

  1. Pitfalls in ictal EEG interpretation: critical care and intracranial recordings.

    PubMed

    Gaspard, Nicolas; Hirsch, Lawrence J

    2013-01-01

    EEG is the cornerstone examination for seizure diagnosis, especially nonconvulsive seizures in the critically ill, but is still subject to many errors that can lead to a wrong diagnosis and unnecessary or inadequate treatment. Many of these pitfalls to EEG interpretation are avoidable. This article reviews common errors in EEG interpretation, focusing on ictal or potentially ictal recordings obtained in critically ill patients. Issues discussed include artifacts, nonepileptic events, equivocal EEG patterns seen in comatose patients, and quantitative EEG artifacts. This review also covers some difficulties encountered with intracranial EEG recordings in patients undergoing epilepsy surgery, including issues related to display resolution.

  2. Viscoelastic Disc Arthroplasty Provides Superior Back and Leg Pain Relief in Patients with Lumbar Disc Degeneration Compared to Anterior Lumbar Interbody Fusion.

    PubMed

    Rischke, Burkhard; Zimmers, Kari B; Smith, Eric

    2015-01-01

    Lumbar disc degeneration (LDD) is one of the most frequently diagnosed spinal diseases. The symptoms these disorders cause are anticipated to increase as the population in Western countries ages. Compare back and leg pain alleviation in patients with LDD and a viscoelastic disc prosthesis documented in the SWISSspine registry versus patients with anterior lumbar interbody fusion documented in the Spine Tango registry. Prospectively collected clinical and outcome data in two independent spine registries. Outcome Measures were back and leg pain relief on 0 to 10 numerical rating scales. The analysis included a single surgeon series of 48 patients with viscoelastic total disc replacement (VTDR) from the SWISSspine registry which were compared to 131 patients with anterior lumbar interbody fusion (ALIF) from the Spine Tango registry. Two linear multivariate regression models were built to assess the associations of patient characteristics with back and leg pain relief. The following covariates were included in the models: patient age and sex, disc herniation as additional diagnosis, number of treated segments, level of treated segment, treatment type (VTDR, ALIF), preoperative back and leg pain levels and follow-up interval. Both models showed VTDR to be associated with significantly higher back (2.76 points; 95% confidence interval (CI) 1.78 - 3.73; p < 0.001) and leg pain (2.12 points; 95% CI 1.12 to 3.13; p < 0.001) relief than ALIF. Other influential factors for higher back pain relief were female sex compared with male sex (1.03 additional points; 95% CI 0.27 to 1.78; p = 0.008), monosegmental surgery compared with bisegmental surgery (1.02 additional points; 95% CI 0.21 to 1.83; p = 0.014), and higher back pain at baseline (0.87 points additional pain relief per level of preoperative back pain; 95% CI 0.70 to 1.03; p < 0.001). Other influential factors for leg pain relief were monosegmental surgery (0.93 additional points; 95% CI 0.10 to 1.77; p = 0.029) and

  3. Use NASA GES DISC Data in ArcGIS

    NASA Technical Reports Server (NTRS)

    Yang, Wenli; Pham, Long B.; Kempler, Steve

    2015-01-01

    This presentation describes GIS relevant data at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), GES DISC Services and Support for GIS Users, and use cases of GES DISC data in ArcGIS.

  4. Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings

    NASA Astrophysics Data System (ADS)

    Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa

    2004-09-01

    The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.

  5. Assessment of Magnetic Resonance Imaging Artifact Following Cervical Total Disc Arthroplasty

    PubMed Central

    Fayyazi, Amir H.; Taormina, Jennifer; Svach, David; Stein, Jeff

    2015-01-01

    Background Cervical disc arthroplasty has become a technique for the treatment of cervical degenerative disc disease. Clinically, the need to accurately assess the neural elements at the operative and adjacent levels is critical postoperatively. The purpose of this study was to quantitatively and qualitatively measure the amount of MRI artifact produced by various cervical total disc replacements. Methods T1 and T2-weighted turbo spin-echo MRI sequences were collected on the cervical spine (C2-T1) of a 68 year-old unembalmed male cadaver. A discectomy was performed at C5-6, followed by successive implantation of six different total disc replacements. The scans were quantitatively evaluated by three of the authors. The volume of artifact was measured using image analysis software. Qualitative analysis of the adjacent and index neural elements was performed. Results The artifact in the T2 weighted images was noted to be 58.6±7.3 cm3 for Prestige ST, 14.2±1.3 cm3 for ProDisc-C, 7.5±0.8 cm3 for Discover, 8.0±0.3 cm3 for Prestige LP, 6.6±0.7 cm3 for Bryan, and 7.3±0.6 cm3 for ProDisc-C titanium prototype. Acceptable intraobserver and excellent interobsever correlation was demonstrated using Pearson Correlation and Concordance Correlation Coefficient analysis. The adjacent and implanted level neural elements (spinal cord and neuroforamina) were easily visualized on the T2 weighted images after the implantation of titanium devices (ProDisc-C titanium prototype, Discover, Prestige LP and Bryan). After implantation of a cobalt chrome implant (ProDisc-C), the adjacent level neural elements were easily visualized but the implanted level could not be fully visualized due to distortion of the images. The quality of the distortion was least favorable after the implantation of the stainless steel implant (Prestige ST), where neither the adjacent nor the index level could be fully visualized. Conclusion The volume of the artifact seen following cervical total disc

  6. Radiation Source Replacement Workshop

    SciTech Connect

    Griffin, Jeffrey W.; Moran, Traci L.; Bond, Leonard J.

    2010-12-01

    This report summarizes a Radiation Source Replacement Workshop in Houston Texas on October 27-28, 2010, which provided a forum for industry and researchers to exchange information and to discuss the issues relating to replacement of AmBe, and potentially other isotope sources used in well logging.

  7. MDCA Needle 1 Replacement

    NASA Image and Video Library

    2013-04-22

    ISS035-E-025557(22 April 2013) ---Multi-user Droplet Combustion Apparatus (MDCA) Hardware Replacement: Cassidy accessed the Combustion Integration Rack (CIR) Combustion Chamber and removed the MDCA Chamber Insert Assembly (CIA). He then replaced the MDCA Needle 1 due to a fuel line that was damaged during previous activities when the MDCA CIA was being removed from the Combustion Chamber.

  8. Leaf-disc grafting for the transmission of Candidatus Liberibacter asiaticus in citrus (Citrus sinensis; Rutaceae) seedlings1

    PubMed Central

    Tabay Zambon, Flavia; Plant, Karen; Etxeberria, Ed

    2017-01-01

    Premise of the study: The search for resistance/tolerance to the devastating citrus huanglongbing disease (syn. HLB or citrus greening) is generating an increasing number of new plants of diverse genetic makeup. As the increasing number of new plants require more space, resources, and time, the need for faster and more efficient HLB screening tests becomes crucial. Methods and Results: The leaf-disc grafting system described here consists in replacing a disc of leaf tissue with a similar disc from an infected plant. This can be performed in young seedlings not yet big enough to endure other types of grafting. Graft success and infection rates average approximately 80%. Conclusions: We describe the successful adaptation of leaf-disc grafting as a powerful screening tool for HLB. The system requires minimal plant material and can be performed in seedlings at a very young age with increased efficiency in terms of time, space, and resources. PMID:28090406

  9. Leaf-disc grafting for the transmission of Candidatus Liberibacter asiaticus in citrus (Citrus sinensis; Rutaceae) seedlings.

    PubMed

    Tabay Zambon, Flavia; Plant, Karen; Etxeberria, Ed

    2017-01-01

    The search for resistance/tolerance to the devastating citrus huanglongbing disease (syn. HLB or citrus greening) is generating an increasing number of new plants of diverse genetic makeup. As the increasing number of new plants require more space, resources, and time, the need for faster and more efficient HLB screening tests becomes crucial. The leaf-disc grafting system described here consists in replacing a disc of leaf tissue with a similar disc from an infected plant. This can be performed in young seedlings not yet big enough to endure other types of grafting. Graft success and infection rates average approximately 80%. We describe the successful adaptation of leaf-disc grafting as a powerful screening tool for HLB. The system requires minimal plant material and can be performed in seedlings at a very young age with increased efficiency in terms of time, space, and resources.

  10. Development of a rapid matrix digestion technique for ultrastructural analysis of elastic fibers in the intervertebral disc.

    PubMed

    Tavakoli, Javad; Costi, John J

    2017-07-01

    Collagen and elastic fibers are two major fibrous constituents of the annulus fibrosus (AF) in the disc that contribute to its mechanical and viscoelastic properties. It was thought that elastic fibers play no substantial role in the function and properties of the disc as these fibers were irregularly distributed. Studies that have revealed highly organized elastic fibers with different regional orientation and distribution, while being strongly crosslinked with matrix, suggesting their contribution to disc structure-function properties. These studies that were performed by light microscopic analysis of histologically prepared samples, have not been able to reveal the fine-scale architectural details of the elastic fiber network. Since elastic fibers are intermingled with other fibrous components of the disc and mostly obscured by the extracellular matrix, it is difficult to demonstrate their ultra-structural organization using scanning electron microscopy (SEM). Therefore the aim of this study was to develop a rapid matrix digestion technique for ultrastructural analysis of the disc elastic fibers. This study provides a new method for fundamental visualization of elastic fibers and their architecture in the disc. Through the ultra-structural analysis, the relationship between structure and function, as well as the role of elastic fibers on AF mechanical properties can be studied. This method may be used to develop a three-dimensional map of elastic fibers distribution within the disc, which would provide valuable information for designing tissue engineered scaffolds for AF repair and replacement. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  12. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  13. 46 CFR 64.61 - Rupture disc.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...

  14. Rapid radiative clearing of protoplanetary discs

    NASA Astrophysics Data System (ADS)

    Haworth, Thomas J.; Clarke, Cathie J.; Owen, James E.

    2016-04-01

    The lack of observed transition discs with inner gas holes of radii greater than ˜50 au implies that protoplanetary discs dispersed from the inside out must remove gas from the outer regions rapidly. We investigate the role of photoevaporation in the final clearing of gas from low mass discs with inner holes. In particular, we study the so-called `thermal sweeping' mechanism which results in rapid clearing of the disc. Thermal sweeping was originally thought to arise when the radial and vertical pressure scalelengths at the X-ray heated inner edge of the disc match. We demonstrate that this criterion is not fundamental. Rather, thermal sweeping occurs when the pressure maximum at the inner edge of the dust heated disc falls below the maximum possible pressure of X-ray heated gas (which depends on the local X-ray flux). We derive new critical peak volume and surface density estimates for rapid radiative clearing which, in general, result in rapid dispersal happening less readily than in previous estimates. This less efficient clearing of discs by X-ray driven thermal sweeping leaves open the issue of what mechanism (e.g. far-ultraviolet heating) can clear gas from the outer disc sufficiently quickly to explain the non-detection of cold gas around weak line T Tauri stars.

  15. Circular plate capacitor with different discs

    NASA Astrophysics Data System (ADS)

    Paffuti, Giampiero; Cataldo, Enrico; Di Lieto, Alberto; Maccarrone, Francesco

    2016-10-01

    In this paper, we write a system of integral equations for a capacitor composed of two discs of different radii, generalizing Love's equation for equal discs. We compute the complete asymptotic form of the capacitance matrix for both large and small distances obtaining a generalization of Kirchhoff's formula for the latter case.

  16. Spiral Waves in Accretion Discs - Theory

    NASA Astrophysics Data System (ADS)

    Boffin, H. M. J.

    Spirals shocks have been widely studied in the context of galactic dynamics and protostellar discs. They may however also play an important role in some classes of close binary stars, and more particularly in cataclysmic variables. In this paper, we review the physics of spirals waves in accretion discs, present the results of numerical simulations and consider whether theory can be reconcilied with observations.

  17. The inner cavity of the circumnuclear disc

    NASA Astrophysics Data System (ADS)

    Blank, M.; Morris, M. R.; Frank, A.; Carroll-Nellenback, J. J.; Duschl, W. J.

    2016-06-01

    The circumnuclear disc (CND) orbiting the Galaxy's central black hole is a reservoir of material that can ultimately provide energy through accretion, or form stars in the presence of the black hole, as evidenced by the stellar cluster that is presently located at the CND's centre. In this paper, we report the results of a computational study of the dynamics of the CND. The results lead us to question two paradigms that are prevalent in previous research on the Galactic Centre. The first is that the disc's inner cavity is maintained by the interaction of the central stellar cluster's strong winds with the disc's inner rim, and secondly, that the presence of unstable clumps in the disc implies that the CND is a transient feature. Our simulations show that, in the absence of a magnetic field, the interaction of the wind with the inner disc rim actually leads to a filling of the inner cavity within a few orbital time-scales, contrary to previous expectations. However, including the effects of magnetic fields stabilizes the inner disc rim against rapid inward migration. Furthermore, this interaction causes instabilities that continuously create clumps that are individually unstable against tidal shearing. Thus the occurrence of such unstable clumps does not necessarily mean that the disc is itself a transient phenomenon. The next steps in this investigation are to explore the effect of the magnetorotational instability on the disc evolution and to test whether the results presented here persist for longer time-scales than those considered here.

  18. Dependence of optic disc parameters on disc area according to Heidelberg Retina Tomograph: Part II.

    NASA Astrophysics Data System (ADS)

    Machekhin, V.; Manaenkova, G.; Bondarenko, O.

    2007-05-01

    With the help of Heidelberg Retina Tomograph (HRT-II) optic disc parameters in 211 eyes of 115 healthy patients with refraction Em +/- 3,0 D and 96 eyes of 72 patients with myopia 3,5-14,0 D without any signs of glaucoma were studied. Analysis of optic disc parameters were carried out in 5 groups of patients according to disc area: less than 1,5 mm2, 1,5- 2,5 mm2, 2,5-3,0 mm2, 3,0-3,5 mm2 and more than 3,5 mm2. An accurate depending on disc area was revealed for all optic disc parameters in all sectors, which was manifested by increasing cup disc and rim disc (area and volume) and other parameters. We consider it is necessary to use the proper tables for right interpretation of received data for early diagnosis of glaucoma.

  19. (*) In Vitro Generated Intervertebral Discs: Toward Engineering Tissue Integration.

    PubMed

    Iu, Jonathan; Massicotte, Eric; Li, Shu-Qiu; Hurtig, Mark B; Toyserkani, Ehsan; Santerre, J Paul; Kandel, Rita A

    2017-09-01

    The intervertebral disc (IVD) is composed of nucleus pulposus (NP) surrounded by multilamellated annulus fibrosus (AF), and is located between the vertebral bodies. Current treatments for chronic neck or low back pain do not completely restore the functionality of degenerated IVDs. Thus, developing biological disc replacements is an approach of great interest. Given the complex structure of the IVD, tissue engineering of the individual IVD components and then combining them together may be the only way to achieve this. The engineered disc must then be able to integrate into the host spine to ensure mechanical stability. The goal of this study was to generate an integrated model of an IVD in vitro. Multilamellated AF tissues were generated in vitro using aligned nanofibrous polycarbonate urethane scaffolds and AF cells. After 3 weeks in culture, it was placed around NP tissue formed on and integrated with a porous bone substitute material (calcium polyphosphate). The two tissues were cocultured to fabricate the IVD model. The AF tissue composed of six lamellae containing type I collagen-rich extracellular matrix (ECM) and the NP tissue had type II collagen- and aggrecan-rich ECM. Immunofluorescence studies showed both type I and II collagen at the AF-NP interface. There was evidence of integration of the tissues. The peel test for AF lamellae showed an interlamellar shear stress of 0.03 N/mm. The AF and NP were integrated as the pushout test demonstrated that the AF-NP interface had significantly increased mechanical stability by 2 weeks of coculture. To evaluate if these tissues remained integrated, allogeneic IVD model constructs were implanted into defects freshly made in the NP-inner AF and bone of the bovine coccygeal spine. One month postimplantation, the interfaces between the AF lamellae remained intact and there was integration with the host AF tissue. No inflammatory reaction was noted at this time period. In summary, an engineered IVD implant with

  20. Development of injectable hydrogels for nucleus pulposus replacement

    NASA Astrophysics Data System (ADS)

    Thomas, Jonathan D.

    Intervertebral disc degeneration has been reported as the underlying cause for 75% of cases of lower back pain and is marked by dehydration of the nucleus pulposus within the intervertebral disc. There have been many implant designs to replace the nucleus pulposus. Some researchers have proposed the replacement of the nucleus pulposus with hydrogel materials. The insertion of devices made from these materials further compromises the annulus of the disc. An ideal nucleus replacement could be injected into the disc space and form a solid in vivo. However, injectable replacements using curing elastomers and thermoplastic materials are not ideal because of the potentially harmful exothermic heat evolved from their reactions and the toxicity of the reactants used. We propose a hydrogel system that can be injected as a liquid at 25°C and solidified to yield a hydrogel within the intervertebral disc at 37°C. In aqueous solutions, these polymers have Lower Critical Solution Temperatures (LCST) between 25-37°C, making them unique candidate materials for this application. Poly(N-isopropylacrylamide) (PNIPAAm) is the most widely studied LCST polymer due to its drastic transition near body temperature. However, by itself, pure PNIPAAm forms a hydrogel that has low water content and can readily undergo plastic deformation. To increase the water content and impart elasticity to PNIPAAm hydrogels, grafted and branched hydrogel systems were created that incorporated the thermogelling PNIPAAm and hydrophilic poly(ethylene glycol) (PEG). In this research, the effects of polymer composition and monomer to initiator ratio, which controls polymer MW, on the in vitro swelling properties (mass, chemical, and compressive mechanical stability) of hydrogels formed from aqueous solutions of these polymers were evaluated. Immersion studies were also conducted in solutions to simulate the osmotic environment of the nucleus pulposus. The effects of repeated compression and unloading cycles

  1. Roentgenographic measurement of lumbar intervertebral disc height.

    PubMed

    Andersson, G B; Schultz, A; Nathan, A; Irstam, L

    1981-01-01

    The influences of differences in both intervertebral motion segment orientations and in reader judgments on measurements of the apparent intervertebral disc heights in lateral roentgenographs of the lumbar spine were examined. Forty-nine roentgenographs were obtained of nine discs that were titled laterally up to +/- 10 degrees, and rotated longitudinally up to +/- 20 degrees. Three orthopaedic surgeons and three radiologists measured disc heights from five of these roentgenographs, all using the same measurement method. The differences in apparent height that resulted from the orientation changes and differences in judgments among the six readers were considerable, usually of the order of one half of the nominal disc height. The results show that, while roentgenographic measurements can be used to estimate disc height, accurate measurements cannot readily be made from routine roentgenographs, and the interpretation should always be cautious.

  2. About detection of precessing circumpulsar discs

    NASA Astrophysics Data System (ADS)

    Grimani, Catia

    2016-08-01

    Detections of circumpulsar discs and planetary systems through electromagnetic observations appear quite rare. In the case of PSR 1931+24 and B0656+14, the hypothesis of a precessing disc penetrating the pulsar light cylinder is found consistent with radio and gamma observations from these stars. Disc self-occultation and precession may affect electromagnetic measurements. We investigate here under which conditions gravitational waves generated by circumpulsar disc precession may be detected by the proposed second-generation space interferometers DECI-hertz Interferometer Gravitational Wave Observatory and Big Bang Observer. The characteristics of circumpulsar detectable precessing discs are estimated as a function of distance from the Solar system. Speculations on detection rates are presented.

  3. Optic disc dysplasia in poland syndrome.

    PubMed

    Maxfield, Steven D; Strominger, Mitchell B

    2014-06-01

    To report optic disc dysplasia in a case of Poland syndrome. Non-interventional case report. A 2-year-old boy with Poland syndrome was referred for ophthalmic evaluation after abnormal optic discs were found on exam. Physical exam at birth revealed right-sided aplasia of the pectoralis major muscle, symbrachydactyly, hypoplastic scapula, and an abnormal third rib. On dilated examination the optic nerve heads were dysplastic. The findings included multiple cilioretinal vessels, situs inversus, inferotemporal excavation, and surrounding pigmentary disturbances. Only one case of optic disc anomaly has been reported in Poland syndrome and was described as morning glory syndrome. The optic discs in our patient do not fit well with other optic disc excavation syndromes but are most reminiscent of those in papillorenal syndrome. As both Poland syndrome and papillorenal syndrome share vascular dysfunction as a possible etiology, this case adds to the literature of vascular dysgenesis in Poland syndrome.

  4. Strongly magnetized accretion discs require poloidal flux

    NASA Astrophysics Data System (ADS)

    Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.

    2016-08-01

    Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.

  5. Lumbar Epidural Varix Mimicking Disc Herniation

    PubMed Central

    Bursalı, Adem; Guvenal, Ahmet Burak; Yaman, Onur

    2016-01-01

    Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4–5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525

  6. Shock absorption in lumbar disc prosthesis: a preliminary mechanical study.

    PubMed

    LeHuec, J C; Kiaer, T; Friesem, T; Mathews, H; Liu, M; Eisermann, L

    2003-08-01

    Lumbar disc prostheses have been used in treating symptomatic degenerative disc diseases. A few prostheses of the ball-socket design are currently available for clinical use, the joint mechanism being materialized either with a hard polymer core or a metal-to-metal couple. Other prostheses of "shock absorber" design were not available at the time of the study. The objective of this work was to establish whether there was a difference in the shock absorption capacity between a device having an ultra-high-molecular-weight polyethylene center core and a device having a metal-on-metal bearing. Vibration and shock loading were applied to two lumbar total disc prostheses: PRODISC, manufactured by Spine Solutions, and MAVERICK Total Disc Replacement, manufactured by Medtronic Sofamor Danek. The shock absorption capacity of the device was evaluated by comparing the input and the output force measurements. The disc prosthesis was mounted onto a test apparatus. Each side of the device was equipped with a force sensor. The input shock load and the output resulting forces were simultaneously measured and recorded. The loading force pattern included 1). a static preload of 350 N plus an oscillating vibration of 100 N with frequency sweeping from 0 to 100 Hz and 2). a sudden shock load of 250 N applied over a 0.1-second interval. Both input and output signal data were processed and were transformed into their frequency spectrums. The vibration and shock transmissibility of the device, defined as the ratio of the output spectrum over the input spectrum, were calculated in sweeping the frequency from 0 to 100 Hz. The phase deviation was calculated to characterize the shock absorber effects. For both tested devices under vibration and shock loading, the phase angle displacement between the input and the output signals was 10 degrees. Under oscillating vibration loading, both tested devices had a transmission ratio higher than 99.8%. Over the frequency interval 1-100 Hz, the

  7. The role of thermodynamics in disc fragmentation

    NASA Astrophysics Data System (ADS)

    Stamatellos, Dimitris; Whitworth, Anthony P.

    2009-12-01

    Thermodynamics play an important role in determining the way a protostellar disc fragments to form planets, brown dwarfs and low-mass stars. We explore the effect that different treatments of radiative transfer have in simulations of fragmenting discs. Three prescriptions for the radiative transfer are used: (i) the diffusion approximation of Stamatellos et al.; (ii) the barotropic equation of state (EOS) of Goodwin et al. and (iii) the barotropic EOS of Bate et al. The barotropic approximations capture the general evolution of the density and temperature at the centre of each proto-fragment but (i) they do not make any adjustments for particular circumstances of a proto-fragment forming in the disc and (ii) they do not take into account thermal inertia effects that are important for fast-forming proto-fragments in the outer disc region. As a result, the number of fragments formed in the disc and their properties are different, when a barotropic EOS is used. This is important not only for disc studies but also for simulations of collapsing turbulent clouds, as in many cases in such simulations stars form with discs that subsequently fragment. We also examine the difference in the way proto-fragments condense out in the disc at different distances from the central star using the diffusion approximation and following the collapse of each proto-fragment until the formation of the second core (ρ ~= 10-3gcm-3). We find that proto-fragments forming closer to the central star tend to form earlier and evolve faster from the first to the second core than proto-fragments forming in the outer disc region. The former have a large pool of material in the inner disc region that they can accrete from and grow in mass. The latter accrete more slowly and they are hotter because they generally form in a quick abrupt event.

  8. Pitfalls of CITES implementation in Nepal: a policy gap analysis.

    PubMed

    Dongol, Yogesh; Heinen, Joel T

    2012-08-01

    Implementation of policy involves multiple agencies operating at multiple levels in facilitating processes and actions to accomplish desired results. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was developed and implemented to regulate and control international wildlife trade, but violations of the agreement are widespread and growing worldwide, including in Nepal. This study attempts to understand how domestic CITES policies are translated into action and what effect actions and processes have on compliance. In doing so, this study provides insights into the implementation and enforcement pitfalls of national legislation that explain CITES violations in Nepal. Primarily, we used 26 key informants interviews to learn opinions of experts, and the grounded theory approach for further qualitative data analysis. In addition, we used Najman's (1995) policy implementation analysis framework to explain gaps. Many interrelated variables in the content of the policy, commitment and capacity of the agencies, the roles of clients and coalitions and contextual issues were observed. Variables that emerged suggest pitfalls in the regulatory policy represented by low probability of detection, arrest and punishment. Moreover, redistributive policies in buffer zones of protected areas are needed into perpetuity to benefit locals. Also, conservation organizations' support for building public and political salience is imperative.

  9. Pitfalls of CITES Implementation in Nepal: A Policy Gap Analysis

    NASA Astrophysics Data System (ADS)

    Dongol, Yogesh; Heinen, Joel T.

    2012-08-01

    Implementation of policy involves multiple agencies operating at multiple levels in facilitating processes and actions to accomplish desired results. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was developed and implemented to regulate and control international wildlife trade, but violations of the agreement are widespread and growing worldwide, including in Nepal. This study attempts to understand how domestic CITES policies are translated into action and what effect actions and processes have on compliance. In doing so, this study provides insights into the implementation and enforcement pitfalls of national legislation that explain CITES violations in Nepal. Primarily, we used 26 key informants interviews to learn opinions of experts, and the grounded theory approach for further qualitative data analysis. In addition, we used Najman's (1995) policy implementation analysis framework to explain gaps. Many interrelated variables in the content of the policy, commitment and capacity of the agencies, the roles of clients and coalitions and contextual issues were observed. Variables that emerged suggest pitfalls in the regulatory policy represented by low probability of detection, arrest and punishment. Moreover, redistributive policies in buffer zones of protected areas are needed into perpetuity to benefit locals. Also, conservation organizations' support for building public and political salience is imperative.

  10. Big data in sleep medicine: prospects and pitfalls in phenotyping.

    PubMed

    Bianchi, Matt T; Russo, Kathryn; Gabbidon, Harriett; Smith, Tiaundra; Goparaju, Balaji; Westover, M Brandon

    2017-01-01

    Clinical polysomnography (PSG) databases are a rich resource in the era of "big data" analytics. We explore the uses and potential pitfalls of clinical data mining of PSG using statistical principles and analysis of clinical data from our sleep center. We performed retrospective analysis of self-reported and objective PSG data from adults who underwent overnight PSG (diagnostic tests, n=1835). Self-reported symptoms overlapped markedly between the two most common categories, insomnia and sleep apnea, with the majority reporting symptoms of both disorders. Standard clinical metrics routinely reported on objective data were analyzed for basic properties (missing values, distributions), pairwise correlations, and descriptive phenotyping. Of 41 continuous variables, including clinical and PSG derived, none passed testing for normality. Objective findings of sleep apnea and periodic limb movements were common, with 51% having an apnea-hypopnea index (AHI) >5 per hour and 25% having a leg movement index >15 per hour. Different visualization methods are shown for common variables to explore population distributions. Phenotyping methods based on clinical databases are discussed for sleep architecture, sleep apnea, and insomnia. Inferential pitfalls are discussed using the current dataset and case examples from the literature. The increasing availability of clinical databases for large-scale analytics holds important promise in sleep medicine, especially as it becomes increasingly important to demonstrate the utility of clinical testing methods in management of sleep disorders. Awareness of the strengths, as well as caution regarding the limitations, will maximize the productive use of big data analytics in sleep medicine.

  11. Maintenance of imaginal disc plasticity and regenerative potential in Drosophila by p53

    PubMed Central

    Wells, Brent S.; Johnston, Laura A.

    2012-01-01

    Following irradiation (IR), the DNA damage response (DDR) activates p53, which triggers death of cells in which repair cannot be completed. Lost tissue is then replaced and re-patterned through regeneration. We have examined the role of p53 in co-regulation of the DDR and tissue regeneration following IR damage in Drosophila. We find that after IR, p53 is required for imaginal disc cells to repair DNA, and in its absence the damage marker, γ-H2AX is persistently expressed. p53 is also required for the compensatory proliferation and re-patterning of the damaged discs, and our results indicate that cell death is not required to trigger these processes. We identify an IR-induced delay in developmental patterning in wing discs that accompanies an animal-wide delay of the juvenile-adult transition, and demonstrate that both of these delays require p53. In p53 mutants, the lack of developmental delays and of damage resolution leads to anueploidy and tissue defects, and ultimately to morphological abnormalities and adult inviability. We propose that p53 maintains plasticity of imaginal discs by co-regulating the maintenance of genome integrity and disc regeneration, and coordinating these processes with the physiology of the animal. These findings place p53 in a role as master coordinator of DNA and tissue repair following IR. PMID:22036477

  12. Symptoms of thoracolumbar junction disc herniation.

    PubMed

    Tokuhashi, Y; Matsuzaki, H; Uematsu, Y; Oda, H

    2001-11-15

    A retrospective clinical review of patients with thoracolumbar junction disc herniation. To evaluate the clinical features of thoracolumbar junction disc herniation and to prepare a chart for the level diagnosis in the neurologic findings and symptoms. Thoracolumbar junction disc herniations show a variety of signs and symptoms because of the complexity of the upper and lower neurons of the spinal cord, cauda equina, and nerve roots. Furthermore, much is still unknown about thoracolumbar junction disc herniations because of their rare frequency. The clinical features of 26 patients who had undergone operations for single disc herniations at T10-T11 through L2-L3 were investigated. Affected levels were as follows: 2 patients with disc herniation at T10-T11 disc, 4 patients at T11-T12, 3 patients at T12-L1, 6 patients at L1-L2, and 11 patients at L2-L3. The level of disc space of interest was confirmed with whole-spine plain roentgenograms. The caudal end of the cord was judged by magnetic resonance imaging and computed tomographic myelogram. Two patients with T10-T11 disc herniation showed moderate lower extremity weakness, increased patellar tendon reflex, and sensory disturbance of the entire lower extremities. Three of four patients with T11-T12 disc herniation experienced lower extremity weakness, and three patients had accentuated patellar tendon reflex. Sensory disturbance was observed in the anterolateral aspect of the thigh in one patient and on the entire leg in three patients. Bowel and bladder dysfunction was noted in three patients. In the T12-L1 disc herniation group (n = 3), muscle weakness and atrophy below the leg were advanced, and bowel and bladder dysfunction were also noted. Two of these three patients had bilateral drop foot, and one patient had unilateral drop foot; sensory disturbance was noted in the sole or foot and around the circumference of the anus, and the patellar tendon reflex and Achilles tendon reflex were absent. All six patients

  13. Rehabilitation after lumbar disc surgery.

    PubMed

    Ostelo, R W; de Vet, H C; Waddell, G; Kerckhoffs, M R; Leffers, P; van Tulder, M W

    2002-01-01

    Although several rehabilitation programs, physical fitness programs or protocols regarding instruction for patients to return to work after lumbar disc surgery have been suggested, little is known about the efficacy and effectiveness of these treatments. There are still persistent fears of causing re-injury, re-herniation, or instability. The objective of this systematic review was to evaluate the effectiveness of active treatments that are used in the rehabilitation after first-time lumbar disc surgery. We searched the MEDLINE, EMBASE and Psyclit databases up to April 2000 and the Cochrane Controlled Trials Register 2001, Issue 3. Both randomized and non-randomized controlled trials on any type of active rehabilitation program after first-time disc surgery were included. Two independent reviewers performed the inclusion of studies and two other reviewers independently performed the methodological quality assessment. A rating system that consists of four levels of scientific evidence summarizes the results. Thirteen studies were included, six of which were of high quality. There is no strong evidence for the effectiveness for any treatment starting immediately post-surgery, mainly because of lack of (good quality) studies. For treatments that start four to six weeks post-surgery there is strong evidence (level 1) that intensive exercise programs are more effective on functional status and faster return to work (short-term follow-up) as compared to mild exercise programs and there is strong evidence (level 1) that on long term follow up there is no difference between intensive exercise programs and mild exercise programs with regard to overall improvement. For all other primary outcome measures for the comparison between intensive and mild exercise programs there is conflicting evidence (level 3) with regard to long-term follow-up. Furthermore, there is no strong evidence for the effectiveness of supervised training as compared to home exercises. There was also no

  14. Comparative charge analysis of one- and two-level lumbar total disc arthroplasty versus circumferential lumbar fusion.

    PubMed

    Levin, David A; Bendo, John A; Quirno, Martin; Errico, Thomas; Goldstein, Jeffrey; Spivak, Jeffrey

    2007-12-01

    This is a retrospective, independent study comparing 2 groups of patients treated surgically for discogenic low back pain associated with degenerative disc disease (DDD) in the lumbosacral spine. To compare the surgical and hospitalization charges associated with 1- and 2-level lumbar total disc replacement and circumferential lumbar fusion. Reported series of lumbar total disc replacement have been favorable. However, economic aspects of lumbar total disc replacement (TDR) have not been published or studied. This information is important considering the recent widespread utilization of new technologies. Recent studies have demonstrated comparable short-term clinical results between TDR and lumbar fusion recipients. Relative charges may be another important indicator of the most appropriate procedure. We report a hospital charge-analysis comparing ProDisc lumbar disc replacement with circumferential fusion for discogenic low back pain. In a cohort of 53 prospectively selected patients with severe, disabling back pain and lumbar disc degeneration, 36 received Synthes ProDisc TDR and 17 underwent circumferential fusion for 1- and 2-level degenerative disc disease between L3 and S1. Randomization was performed using a 2-to-1 ratio of ProDisc recipients to control spinal fusion recipients. Charge comparisons, including operating room charges, inpatient hospital charges, and implant charges, were made from hospital records using inflation-corrected 2006 U.S. dollars. Operating room times, estimated blood loss, and length of stay were obtained from hospital records as well. Surgeon and anesthesiologist fees were, for the purposes of comparison, based on Medicare reimbursement rates. Statistical analysis was performed using a 2-tailed Student t test. For patients with 1-level disease, significant differences were noted between the TDR and fusion control group. The mean total charge for the TDR group was $35,592 versus $46,280 for the fusion group (P = 0.0018). Operating

  15. Lumbar herniated disc: spontaneous regression

    PubMed Central

    Yüksel, Kasım Zafer

    2017-01-01

    Background Low back pain is a frequent condition that results in substantial disability and causes admission of patients to neurosurgery clinics. To evaluate and present the therapeutic outcomes in lumbar disc hernia (LDH) patients treated by means of a conservative approach, consisting of bed rest and medical therapy. Methods This retrospective cohort was carried out in the neurosurgery departments of hospitals in Kahramanmaraş city and 23 patients diagnosed with LDH at the levels of L3−L4, L4−L5 or L5−S1 were enrolled. Results The average age was 38.4 ± 8.0 and the chief complaint was low back pain and sciatica radiating to one or both lower extremities. Conservative treatment was administered. Neurological examination findings, durations of treatment and intervals until symptomatic recovery were recorded. Laségue tests and neurosensory examination revealed that mild neurological deficits existed in 16 of our patients. Previously, 5 patients had received physiotherapy and 7 patients had been on medical treatment. The number of patients with LDH at the level of L3−L4, L4−L5, and L5−S1 were 1, 13, and 9, respectively. All patients reported that they had benefit from medical treatment and bed rest, and radiologic improvement was observed simultaneously on MRI scans. The average duration until symptomatic recovery and/or regression of LDH symptoms was 13.6 ± 5.4 months (range: 5−22). Conclusions It should be kept in mind that lumbar disc hernias could regress with medical treatment and rest without surgery, and there should be an awareness that these patients could recover radiologically. This condition must be taken into account during decision making for surgical intervention in LDH patients devoid of indications for emergent surgery. PMID:28119770

  16. Development and Translation of a Tissue-Engineered Disc in a Preclinical Rodent Model

    DTIC Science & Technology

    2011-10-01

    We have shown that a short period of exposure to transforming at a high dose is equal to or better than long term exposure for stem cells cultured...seeded with adult stem cells that can be used to replace the degenerate native disc. Proposed Aim 1: Create a mesenchymal stem cell (MSC) seeded 3D...establishes the NP and AF cell phenotype. Our focus here was on the formation and maturation of the mesenchymal stem cell (MSC) based nucleus pulposus (NP

  17. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level

    PubMed Central

    Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818

  18. Migration and kinematics in growing disc galaxies with thin and thick discs

    NASA Astrophysics Data System (ADS)

    Aumer, Michael; Binney, James; Schönrich, Ralph

    2017-09-01

    We analyse disc heating and radial migration in N-body models of growing disc galaxies with thick and thin discs. Similar to thin-disc-only models, galaxies with appropriate non-axisymmetric structures reproduce observational constraints on radial disc heating in and migration to the Solar Neighbourhood (Snhd). The presence of thick discs can suppress non-axisymmetries and thus higher baryonic-to-dark matter fractions are required than in models that only have a thin disc. Models that are baryon dominated to roughly the Solar radius R0 are favoured, in agreement with data for the Milky Way. For inside-out growing discs, today's thick-disc stars at R0 are dominated by outwards migrators. Whether outwards migrators are vertically hotter than non-migrators depends on the radial gradient of the thick-disc vertical velocity dispersion. There is an effective upper boundary in angular momentum that thick-disc stars born in the centre of a galaxy can reach by migration, which explains the fading of the high [α/Fe] sequence outside R0. Our models compare well to Snhd kinematics from Radial Velocity Survey and Tycho-Gaia Astrometric Solution data. For such comparisons, it is important to take into account the azimuthal variation of kinematics at R ∼ R0 and biases from survey selection functions. The vertical heating of thin-disc stars by giant molecular clouds is only mildly affected by the presence of thick discs. Our models predict higher vertical velocity dispersions for the oldest stars than found in the Snhd age velocity dispersion relation, possibly because of measurement uncertainties or an underestimation of the number of old cold stars in our models.

  19. [Clinical application of percutaneous laser disc decompression in the treatment of cervical disc herniation].

    PubMed

    Li, Kangren; Qin, Hui; Chen, Jian

    2007-05-01

    To evaluate the clinical effect of percutaneous laser disc decompression (PLDD) in the treatment of cervical disc herniation. From March 2003 to December 2005, 47 patients with cervical disc herniation (96 cervical disc) were treated with PLDD. There were 25 males and 22 females with an average age of 56 years, ranging from 37 to 72 years. The lesion were located at the levels of C3,4 in 20 discs, C4,5 in 27 discs, C5,6 in 31 discs, C6,7 in 18 discs. The laser fiber was introduced into the center of the herniated disc space by percutaneous puncture from anterior neck surface under fluoroscopic guidance. Laser reduced the intra-disc pressure through the vaporization of disc nucleu. The adopted laser was semi-conducted with a wavelength of 810 nm. Each laser output power was 15 W with 1 s emission and 2 s interval. The total laser output power was decided depending on the degenerative degree of the disc and the reactive process of heat, ranging from 300 to 1 000 J. Of 47 patients, 42 were followed up for 3 to 31 months (mean 13 months). The clinical evaluation was classified as excellent in 18 cases (42.9%), good in 14 cases (33.3%), fair in 6 cases (14.3%) and poor in 4 cases (9.5%). The general response rate was 90.5%. The excellent and good rate was 76.2%. No complications occurred. PLDD can relieve the symptoms and signs of patients suffering from cervical disc herniation with less complication. The manipulation of PLDD is easy, safe and mini-invasive.

  20. Ankle replacement - discharge

    MedlinePlus

    ... ankle replacement. Your surgeon removed and reshaped damaged bones, and put in an artificial ankle joint. You received pain medicine and were shown how to treat swelling around your new ankle joint.

  1. Carbohydrates as Fat Replacers.

    PubMed

    Peng, Xingyun; Yao, Yuan

    2017-02-28

    The overconsumption of dietary fat contributes to various chronic diseases, which encourages attempts to develop and consume low-fat foods. Simple fat reduction causes quality losses that impede the acceptance of foods. Fat replacers are utilized to minimize the quality deterioration after fat reduction or removal to achieve low-calorie, low-fat claims. In this review, the forms of fats and their functions in contributing to food textural and sensory qualities are discussed in various food systems. The connections between fat reduction and quality loss are described in order to clarify the rationales of fat replacement. Carbohydrate fat replacers usually have low calorie density and provide gelling, thickening, stabilizing, and other texture-modifying properties. In this review, carbohydrates, including starches, maltodextrins, polydextrose, gums, and fibers, are discussed with regard to their interactions with other components in foods as well as their performances as fat replacers in various systems.

  2. Knee joint replacement - slideshow

    MedlinePlus

    ... presentations/100088.htm Knee joint replacement - series—Normal anatomy To use the sharing features on this page, ... Bethesda, MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated: ...

  3. Replacing a Missing Tooth

    MedlinePlus

    ... vessels in the tooth pulps are rather large. Drilling down these teeth for crowns may expose the ... porcelain replacement tooth is held in place by metal extensions cemented to the backs of the adjacent ...

  4. Hormone Replacement Therapy

    MedlinePlus

    ... before and during menopause, the levels of female hormones can go up and down. This can cause ... hot flashes and vaginal dryness. Some women take hormone replacement therapy (HRT), also called menopausal hormone therapy, ...

  5. Biomechanical Effects of the Geometry of Ball-and-Socket Artificial Disc on Lumbar Spine: A Finite Element Study.

    PubMed

    Choi, Jisoo; Shin, Dong-Ah; Kim, Sohee

    2017-03-15

    A three-dimensional finite element model of intact lumbar spine was constructed and four surgical finite element models implanted with ball-and-socket artificial discs with four different radii of curvature were compared. To investigate biomechanical effects of the curvature of ball-and-socket artificial disc using finite element analysis. Total disc replacement (TDR) has been accepted as an alternative treatment because of its advantages over spinal fusion methods in degenerative disc disease. However, the influence of the curvature of artificial ball-and-socket discs has not been fully understood. Four surgical finite element models with different radii of curvature of ball-and-socket artificial discs were constructed. The range of motion (ROM) increased with decreasing radius of curvature in extension, flexion, and lateral bending, whereas it increased with increasing radius of curvature in axial torsion. The facet contact force was minimum with the largest radius of curvature in extension, flexion, and lateral bending, whereas it was maximum with the largest radius in axial torsion. It was also affected by the disc placement, more with posterior placement than anterior placement. The stress in L4 cancellous bone increased when the radius of curvature was too large or small. The geometry of ball-and-socket artificial disc significantly affects the ROM, facet contact force, and stress in the cancellous bone at the surgical level. The implication is that in performing TDR, the ball-and-socket design may not be ideal, as ROM and facet contact force are sensitive to the disc design, which may be exaggerated by the individual difference of anatomical geometry. N/A.

  6. Stem cells sources for intervertebral disc regeneration

    PubMed Central

    Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo

    2016-01-01

    Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704

  7. The Quiescent Growth Of Galactic Discs

    NASA Astrophysics Data System (ADS)

    Binney, James

    2016-09-01

    We use N-bodies to simulate the growth since redshift 2 of an isolated disc in a live halo. Giant molecular clouds (GMCs), The bar and spiral structure all play key roles in the evolution of the disc. Our GMCs are short-lived and have masses drawn from a mass spectrum. Their number density is related to the SFR. For the expected number densities and likely maximum masses of GMCs, they heat the disc very effectively at early times, and either postpone or cancel bar formation. They generate remarkably exponential vertical profiles. Spiral structure drives a level of radial migration that agrees well with that predicted by models of local chemical evolution. The radial patterns of star formation include different levels of inside-out growth. The radial scale length of the final disc is always greater than any of the scale lengths used for star formation and rather independent of the extent of inside-out growth. The only way to obtain a thick disc nearly as massive as those observed is to include in the initial conditions a massive, extended object that will be compressed into the present thick disc by the gravity of the thin disc.

  8. Shear Mechanics of the TMJ Disc

    PubMed Central

    Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.

    2012-01-01

    The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc’s shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region’s compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc’s regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043

  9. Nonlinear Pixel Replacement Estimation.

    DTIC Science & Technology

    1986-04-01

    Systems Command _________ _______________________ _____ 6e ADDRESS IC,,, Sra,. and ZIP Co~ de , 10 SOURCE Of FUNDING NUMBERS% RORMELEMENT NO PROJECT NO... de - scribed, this method does not replace array elements with computed values, but rather replaces them with one of the nine original pixel values. The...8217, gmx . NOISE PStd dev=’. sd call exit end include ’mathfunc For/nolist’ C-9 c biweighted 3xZ3 filter compute weighted mean from input iara subroutine

  10. Intradiscal pressure measurements in normal discs, compressed discs and compressed discs treated with axial posterior disc distraction: an experimental study on the rabbit lumbar spine model.

    PubMed

    Guehring, Thorsten; Unglaub, Frank; Lorenz, Helga; Omlor, Georg; Wilke, Hans-Joachim; Kroeber, Markus W

    2006-05-01

    Intervertebral disc (IVD) pressure measurement is an appropriate method for characterizing spinal loading conditions. However, there is no human or animal model that provides sufficient IVD pressure data. The aim of our study was to establish physiological pressure values in the rabbit lumbar spine and to determine whether temporary external disc compression and distraction were associated with pressure changes. Measurements were done using a microstructure-based fibreoptic sensor. Data were collected in five control rabbits (N, measurement lying prone at segment L3/4 at day 28), five rabbits with 28 days of axial compression (C, measurement at day 28) and three rabbits with 28 days of axial compression and following 28 days of axial distraction (D, measurement at day 56). Disc compression and distraction was verified by disc height in lateral radiographs. The controls (N) showed a level-related range between 0.25 MPa-0.45 MPa. The IVD pressure was highest at level L3/4 (0.42 MPa; range 0.38-0.45) with a decrease in both cranial and caudal adjacent segments. The result for C was a significant decrease in IVD pressure (0.31 MPa) when compared with controls (P=0.009). D showed slightly higher median IVD pressure (0.32 MPa) compared to C, but significantly lower levels when compared with N (P=0.037). Our results indicate a high range of physiological IVD pressure at different levels of the lumbar rabbit spine. Temporary disc compression reduces pressure when compared with controls. These data support the hypothesis that temporary external compression leads to moderate disc degeneration as a result of degradation of water-binding disc matrix or affected active pumping mechanisms of nutrients into the disc. A stabilization of IVD pressure in discs treated with temporary distraction was observed.

  11. Dynamical instabilities in disc-planet interactions

    NASA Astrophysics Data System (ADS)

    Lin, Min-Kai

    2012-03-01

    Protoplanetary discs may become dynamically unstable due to structure induced by an embedded giant planet. In this thesis, I discuss the stability of such systems and explore the consequence of instability on planetary migration. I begin with non-self-gravitating, low viscosity discs and show that giant planets induce shocks inside its co-orbital region, leading to a profile unstable to vortex formation around a potential vorticity minimum. This instability is commonly known as the vortex or Rossby wave instability. Vortex-planet interaction lead to episodic phases of migration, which can be understood in the framework of type III migration. I then examine the effect of disc self-gravity on gap stability. The linear theory of the Rossby wave instability is extended to include disc gravity, which shows that self-gravity is effective at stabilising the vortex instability at small azimuthal wavenumber. This is consistent with the observation that more vortices develop with increasing disc mass in hydrodynamic simulations. Vortices in self-gravitating discs also resist merging, and is most simply understood as pair-vortices undergoing mutual horsehoe turns upon encounter. I show that in sufficiently massive discs vortex modes are suppressed. Instead, global spiral instabilities develop which are associated with a potential vorticity maximum at the gap edge. These edge modes can be physically understood as a result of unstable interaction between the gap edge and the exterior disc through gravity. I show the spiral arms can provide a positive torque on the planet, leading to fast migration outwards. I confirm the above results, obtained from razor-thin disc models, persist in three-dimensions.

  12. Disc herniations in the National Football League.

    PubMed

    Gray, Benjamin L; Buchowski, Jacob M; Bumpass, David B; Lehman, Ronald A; Mall, Nathan A; Matava, Matthew J

    2013-10-15

    Retrospective analysis of a prospectively collected database. To determine the overall incidence, location, and type of disc herniations in professional football players to target treatment issues and prevention. Disc herniations represent a common and debilitating injury to the professional athlete. The NFL's (National Football League's) Sports Injury Monitoring System is a surveillance database created to monitor the league for all injuries, including injuries to the cervical, thoracic, and lumbar spine. A retrospective analysis was performed on all disc herniations to the cervical, thoracic, and lumbar spine during a 12-season period (2000–2012) using the NFL's surveillance database. The primary data points included the location of the injury, player position, activity at time of injury, and playing time lost due to injury. During the 12 seasons, 275 disc herniations occurred in the spine. In regard to location, 76% occurred in the lumbar spine and most frequently affected the L5–S1 disc. The offensive linemen were most frequently injured. As expected, blocking was the activity that caused most injuries. Lumbar disc herniations rose in prevalence and had a mean loss of playing time of more than half the season (11 games). Thoracic disc herniations led to the largest mean number of days lost overall, whereas players with cervical disc herniations missed the most practices. Disc herniations represent a significant cause of morbidity in the NFL. Although much attention is placed on spinal cord injuries, preventive measures targeting the cervical, thoracic, and lumbar spine may help to reduce the overall incidence of these debilitating injuries. N/A

  13. Chemical separation of disc components using RAVE

    NASA Astrophysics Data System (ADS)

    Wojno, Jennifer; Kordopatis, Georges; Steinmetz, Matthias; McMillan, Paul; Matijevič, Gal; Binney, James; Wyse, Rosemary F. G.; Boeche, Corrado; Just, Andreas; Grebel, Eva K.; Siebert, Arnaud; Bienaymé, Olivier; Gibson, Brad K.; Zwitter, Tomaž; Bland-Hawthorn, Joss; Navarro, Julio F.; Parker, Quentin A.; Reid, Warren; Seabroke, George; Watson, Fred

    2016-10-01

    We present evidence from the RAdial Velocity Experiment (RAVE) survey of chemically separated, kinematically distinct disc components in the solar neighbourhood. We apply probabilistic chemical selection criteria to separate our sample into α-low (`thin disc') and α-high (`thick disc') sequences. Using newly derived distances, which will be utilized in the upcoming RAVE DR5, we explore the kinematic trends as a function of metallicity for each of the disc components. For our α-low disc, we find a negative trend in the mean rotational velocity (Vφ) as a function of iron abundance ([Fe/H]). We measure a positive gradient ∂Vφ/∂[Fe/H] for the α-high disc, consistent with results from high-resolution surveys. We also find differences between the α-low and α-high discs in all three components of velocity dispersion. We discuss the implications of an α-low, metal-rich population originating from the inner Galaxy, where the orbits of these stars have been significantly altered by radial mixing mechanisms in order to bring them into the solar neighbourhood. The probabilistic separation we propose can be extended to other data sets for which the accuracy in [α/Fe] is not sufficient to disentangle the chemical disc components a priori. For such data sets which will also have significant overlap with Gaia DR1, we can therefore make full use of the improved parallax and proper motion data as it becomes available to investigate kinematic trends in these chemical disc components.

  14. Androgen replacement for women.

    PubMed Central

    Basson, R.

    1999-01-01

    OBJECTIVES: To determine whether a postmenopausal syndrome comprising specific changes in sexual desire and response associated with low free testosterone exists. To determine whether this syndrome is ameliorated by testosterone replacement. QUALITY OF EVIDENCE: Literature documenting that replacement of physiological levels of testosterone is beneficial and safe is scant. Only one randomized prospective blinded study examines sexual outcome in detail. MAIN MESSAGE: Testosterone is an important metabolic and sex hormone produced by the ovary throughout life. The variable reduction in ovarian testosterone production coincident with menopause is sometimes associated with a syndrome of specific changes in sexual desire and sexual response. Estrogen deficiency also impairs sexual response, but its replacement will not improve and might exacerbate sexual symptoms from androgen loss. Diagnosis of androgen deficiency is clinical, based on accurate assessment of a woman's sexual status before and after menopause and only confirmed (rather than diagnosed) by a low level of free testosterone. Partial androgen replacement restores much of the sexual response and facilitates sexual desire that is triggered by external cues. Avoiding supraphysiological levels of testosterone lessens risk of masculinization. Avoiding alkylated testosterone lessens hepatic or lipid impairment. CONCLUSION: Further prospective randomized studies of replacement of physiological levels of testosterone in women with androgen deficiency syndrome are needed, using formulations of testosterone available in Canada. The consistency of sexual changes, the associated personal and relationship distress, together with our clinical experience of the gratifying response to physiological replacement, make further studies urgently needed. PMID:10509222

  15. Spectroscopic Parameters of Lumbar Intervertebral Disc Material

    NASA Astrophysics Data System (ADS)

    Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

    2009-06-01

    There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

  16. Fundamental Performance on Disc Type Thermomagnetic Engine

    NASA Astrophysics Data System (ADS)

    Takahashi, Yutaka; Matsuzawa, Tomohiro; Nishikawa, Masahiro

    This paper is described on the fundamental performance of the disc type thermomagnetic engine. The disc type engine has been designed in order to decrease the eddy current braking loss. The performance characteristics such as power, torque and loss has been measured, and compared with that of the cylindrical engine in the condition of the same volume of the temperature sensitive magnetic material. The eddy current braking loss is 0.04W which corresponds to 1/30 the loss in the cylindrical engine at the rotation speed of 0.4rps with the maximum power output. The total loss including partial losses due to the friction, the hydraulic effect and the eddy current braking is 0.9W in the disc type engine and is 1.8W in the cylindrical engine. The total loss in the disc type engine is reduced to be 50% of the value of the total loss in the cylindrical engine at the same condition mentioned above. The maximum output power is 6.0W at the rotation speed of 0.4rps in the disc type engine which is about 1.6 times larger than that of the cylindrical engine. The eddy current braking loss in the disc type engine is 0.7% of the value of the maximum output power, which is negligible effect in this engine. The power per unit volume of disc has the maximum value at the disc width of 40mm. The clearance between discs is decided to be of 1mm due to keeping the working fluid flow condition at a constant. The rotor thickness includes with the clearance and the disc thickness. The power per unit rotor thickness also has the maximum value at the disc thickness of 0.5mm. The thermomagnetic engine with the optimum condition can be designed by using these results. When the permanent magnet fixes the size constant, the disc type engine generates high output power in comparison with the cylindrical engine at the point of effective use of magnetic field.

  17. Optical Disc Utilized As A Data Storage System For Reconnaissance

    NASA Astrophysics Data System (ADS)

    Herzog, Donald G.

    1984-01-01

    Electra-optic and Radar sensing reconnaissance systems have many advantages including remote transmission and image data processing that conventional film camera systems do not have. However, data storage and retrieval that was naturally and easily accomplished with film must now be accommodated by other techniques. The optical disc data storage and retrieval systems offer significant advantage towards fulfilling this need. This paper will provide an overview description of the technology, some of the fundamental alternatives of configuration approach, and some examples of where it may be considered in the reconnaissance system. Silver halide film has been and still is the work horse of the image based reconnaissance field. It will not be replaced in the near future either, but rather a gradual transition to total electronic systems is expected. It is not the intent of this paper to debase film, because in fact it has its advantages. We have learned to optimize its advantages and minimize its disadvantages. However optical disc systems have a definite role to play in the reconnaissance field.

  18. 21 CFR 872.3970 - Interarticular disc prosthesis (interpositional implant).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Interarticular disc prosthesis (interpositional... disc prosthesis (interpositional implant). (a) Identification. An interarticular disc prosthesis... Food and Drug Administration on or before March 30, 1999, for any interarticular disc...

  19. 21 CFR 872.3970 - Interarticular disc prosthesis (interpositional implant).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Interarticular disc prosthesis (interpositional... disc prosthesis (interpositional implant). (a) Identification. An interarticular disc prosthesis... Food and Drug Administration on or before March 30, 1999, for any interarticular disc...

  20. 21 CFR 872.3970 - Interarticular disc prosthesis (interpositional implant).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Interarticular disc prosthesis (interpositional... disc prosthesis (interpositional implant). (a) Identification. An interarticular disc prosthesis... Food and Drug Administration on or before March 30, 1999, for any interarticular disc...

  1. 21 CFR 872.3970 - Interarticular disc prosthesis (interpositional implant).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Interarticular disc prosthesis (interpositional... disc prosthesis (interpositional implant). (a) Identification. An interarticular disc prosthesis... Food and Drug Administration on or before March 30, 1999, for any interarticular disc prosthesis...

  2. Resolution modeling in PET imaging: Theory, practice, benefits, and pitfalls

    PubMed Central

    Rahmim, Arman; Qi, Jinyi; Sossi, Vesna

    2013-01-01

    In this paper, the authors review the field of resolution modeling in positron emission tomography (PET) image reconstruction, also referred to as point-spread-function modeling. The review includes theoretical analysis of the resolution modeling framework as well as an overview of various approaches in the literature. It also discusses potential advantages gained via this approach, as discussed with reference to various metrics and tasks, including lesion detection observer studies. Furthermore, attention is paid to issues arising from this approach including the pervasive problem of edge artifacts, as well as explanation and potential remedies for this phenomenon. Furthermore, the authors emphasize limitations encountered in the context of quantitative PET imaging, wherein increased intervoxel correlations due to resolution modeling can lead to significant loss of precision (reproducibility) for small regions of interest, which can be a considerable pitfall depending on the task of interest. PMID:23718620

  3. Grant-Writing Pearls and Pitfalls: Maximizing Funding Opportunities.

    PubMed

    Liu, Jeffrey C; Pynnonen, Melissa A; St John, Maie; Rosenthal, Eben L; Couch, Marion E; Schmalbach, Cecelia E

    2016-02-01

    This invited article reviews the grant process to include the following objectives: (1) to provide an understanding of otolaryngology funding mechanisms in the context of career progression; (2) to outline key components of a well-written grant; (3) to highlight vital members of a successful research team, with emphasis on the mentor-mentee relationship; and (4) to clarify grant scoring with emphasis on common pitfalls to avoid. Current otolaryngology funding mechanisms and up-to-date resources are provided. The review is aimed to assist otolaryngology residents, faculty new to the grant process, as well as experienced researchers striving to improve their grant review scores. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

  4. Imaging in axial spondyloarthritis: diagnostic problems and pitfalls.

    PubMed

    Baraliakos, Xenofon; Hermann, Kay-Geert A; Braun, Jürgen

    2012-08-01

    Magnetic Structural changes in axial Spondyloarthritis (axSpA) are best identified by conventional radiographs, while magnetic resonance imaging (MRI) is considered the gold standard for assessment of inflammatory changes. Imaging of the axial skeleton is crucial for the diagnosis but also for classification to non-radiographic axSpA according to the 2009 ASAS classification criteria. Despite the existing definitions for a positive MRI for the sacroiliac joints and the spine, these predefined lesions can also be seen in other conditions, representing pitfalls and false-positive conclusions in patients with similar clinical symptoms who do not have SpA. Diagnosis of SpA should result from the combination of clinical, laboratory and imaging findings.

  5. Ecoinformatics (Big Data) for Agricultural Entomology: Pitfalls, Progress, and Promise.

    PubMed

    Rosenheim, Jay A; Gratton, Claudio

    2017-01-31

    Ecoinformatics, as defined in this review, is the use of preexisting data sets to address questions in ecology. We provide the first review of ecoinformatics methods in agricultural entomology. Ecoinformatics methods have been used to address the full range of questions studied by agricultural entomologists, enabled by the special opportunities associated with data sets, nearly all of which have been observational, that are larger and more diverse and that embrace larger spatial and temporal scales than most experimental studies do. We argue that ecoinformatics research methods and traditional, experimental research methods have strengths and weaknesses that are largely complementary. We address the important interpretational challenges associated with observational data sets, highlight common pitfalls, and propose some best practices for researchers using these methods. Ecoinformatics methods hold great promise as a vehicle for capitalizing on the explosion of data emanating from farmers, researchers, and the public, as novel sampling and sensing techniques are developed and digital data sharing becomes more widespread.

  6. Probabilistic language models in cognitive neuroscience: Promises and pitfalls.

    PubMed

    Armeni, Kristijan; Willems, Roel M; Frank, Stefan L

    2017-09-05

    Cognitive neuroscientists of language comprehension study how neural computations relate to cognitive computations during comprehension. On the cognitive part of the equation, it is important that the computations and processing complexity are explicitly defined. Probabilistic language models can be used to give a computationally explicit account of language complexity during comprehension. Whereas such models have so far predominantly been evaluated against behavioral data, only recently have the models been used to explain neurobiological signals. Measures obtained from these models emphasize the probabilistic, information-processing view of language understanding and provide a set of tools that can be used for testing neural hypotheses about language comprehension. Here, we provide a cursory review of the theoretical foundations and example neuroimaging studies employing probabilistic language models. We highlight the advantages and potential pitfalls of this approach and indicate avenues for future research. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Surgery for Locally Recurrent Rectal Cancer: Tips, Tricks, and Pitfalls

    PubMed Central

    Warrier, Satish K.; Heriot, Alexander G.; Lynch, Andrew Craig

    2016-01-01

    Rectal cancer can recur locally in up to 10% of the patients who undergo definitive resection for their primary cancer. Surgical salvage is considered appropriate in the curative setting as well as select cases with palliative intent. Disease-free survival following salvage resection is dependent upon achieving an R0 resection margin. A clear understanding of applied surgical anatomy, appropriate preoperative planning, and a multidisciplinary approach to aggressive soft tissue, bony, and vascular resection with appropriate reconstruction is necessary. Technical tips, tricks, and pitfalls that may assist in managing these cancers are discussed and the roles of additional boost radiation and intraoperative radiation therapy in the management of such cancers are also discussed. PMID:27247536

  8. Surgery for Locally Recurrent Rectal Cancer: Tips, Tricks, and Pitfalls.

    PubMed

    Warrier, Satish K; Heriot, Alexander G; Lynch, Andrew Craig

    2016-06-01

    Rectal cancer can recur locally in up to 10% of the patients who undergo definitive resection for their primary cancer. Surgical salvage is considered appropriate in the curative setting as well as select cases with palliative intent. Disease-free survival following salvage resection is dependent upon achieving an R0 resection margin. A clear understanding of applied surgical anatomy, appropriate preoperative planning, and a multidisciplinary approach to aggressive soft tissue, bony, and vascular resection with appropriate reconstruction is necessary. Technical tips, tricks, and pitfalls that may assist in managing these cancers are discussed and the roles of additional boost radiation and intraoperative radiation therapy in the management of such cancers are also discussed.

  9. Proximal humeral osteoarticular allografts: technique, pearls and pitfalls, outcomes.

    PubMed

    Farfalli, German L; Ayerza, Miguel A; Muscolo, D Luis; Aponte-Tinao, Luis A

    2015-12-01

    Allograft transplantation is a biologic reconstruction option for massive bone defects after resection of bone sarcomas. This type of reconstruction not only restores bone stock but it also allows us to reconstruct the joint anatomically. These factors are a major concern, especially in a young and active population.We are describing indications, surgical techniques, pearls and pitfalls, and outcomes of proximal humeral osteoarticular allografts, done at present time in our institution.We found that allograft fractures and articular complications, as epiphyseal resorption and subchondral fracture, are the main complications observed in proximal humerus osteoarticular allograft reconstructions. Nevertheless, only fractures need a reconstruction revision. Joint complications may adversely affect the limb function, but for this reason, an allograft revision is rarely performed.

  10. Casting: Pearls and pitfalls learned while caring for children's fractures.

    PubMed

    Nguyen, Shawn; McDowell, Mitchell; Schlechter, John

    2016-09-18

    Casting is a routine procedure used for fracture care in the pediatric population. The purpose of this review is to provide pearls and pitfalls that our institution has learned from previous literature. When applying the cast, we recommend using cotton padding for the liner and fiberglass or plaster depending on how much swelling is expected. A well-molded cast must be applied in order to prevent further fracture displacement. Cast valving is a valuable technique that allows a decrease in pressure which prevents discomfort and complications like compartment syndrome. Preventing thermal injuries, skin complications, and a wet cast are other important considerations when caring for casts. Appropriate use of a cast saw, avoiding pressure spots, and properly covering the cast are ways to respectively prevent those complications. Lastly, patient education remains one of the most valuable tools in ensuring proper cast maintenance.

  11. The Promise (and Pitfalls) of Public Health Policy Surveillance.

    PubMed

    Hodge, James G

    2016-08-16

    Though public health policy surveillance is an integral tool in correlating the law to scientifically based public health law studies, drawing accurate legal conclusions from collected data can be challenging. Data may be of poor quality, inaccessible to law and policy makers, or inapplicable to other jurisdictions over time and place. As Burris et al. (2016) advocate, modern, sophisticated, and interactive data collection systems would render more precise legal analysis tied to public health improvements. Although policy surveillance is promising, public health officials, health care providers, attorneys, and researchers must be skilled and prepared to successfully navigate and resolve potential pitfalls for its benefits to be fully realized. Among the significant challenges related to policy surveillance are: (1) timing, (2) agenda setting, (3) predictable misuse, and (4) politics inherent in a federalist public health legal infrastructure. As public health data infrastructure is developed, better legal approaches must be simultaneously crafted to achieve optimal public health outcomes. Copyright © 2016 by Duke University Press.

  12. Chemometrics applied to vibrational spectroscopy: overview, challenges and pitfalls

    SciTech Connect

    Haaland, D.M.

    1996-10-01

    Chemometric multivariate calibration methods are rapidly impacting quantitative infrared spectroscopy in many positive ways. The combination of vibrational spectroscopy and chemometrics has been used by industry for quality control and process monitoring. The growth of these methods has been phenomenal in the past decade. Yet, as with any new technology, there are growing pains. The methods are so powerful at finding correlations in the data, that when used without great care they can readily yield results that are not valid for the analysis of future unknown samples. In this paper, the power of the multivariate calibration methods is discussed while pointing out common pitfalls and some remaining challenges that may slow the implementation of chemometrics in research and industry.

  13. Scrum and Global Delivery: Pitfalls and Lessons Learned

    NASA Astrophysics Data System (ADS)

    Sadun, Cristiano

    Two trends are becoming widespread in software development work—agile development processes and global delivery, both promising sizable benefits in productivity, capacity and so on. Combining the two is a highly attractive possibility, even more so in fast-paced and constrained commercial software engineering projects. However, a degree of conflict exists between the assumptions underlying the two ideas, leading to pitfalls and challenges in agile/distributed projects which are new, both with respect to traditional development and agile or distributed efforts adopted separately. Succeeding in commercial agile/distributed projects implies recognizing these new challenges, proactively planning for them, and actively put in place solutions and methods to overcome them. This chapter illustrates some of the typical challenges that were met during real-world commercial projects, and how they were solved.

  14. The Tips and Pitfalls of Meniscus Allograft Transplantation

    PubMed Central

    Lee, Sung Rak; Nam, Sang Wook

    2012-01-01

    When faced with an irrepairable meniscus or a patient who has had a total or subtotal meniscectomy, meniscus allograft transplantation (MAT) is the preferred modality to restore biomechanical function of the meniscus. The indications for meniscus allograft transplantation are yet to be established. However, currently, MAT has previously been indicated for symptomatic patients who have mild or early osteoarthritis, are younger than 50 years of age, and present with an Outerbridge grade II or lower. The short- to intermediate-term results confirmed noteworthy clinical improvements and consistent objective findings. On the other hand, the successful outcome would be reduced by various complications. Therefore, long-term observation required to evaluate the longevity of these results. The purpose of this article is to review the current research of concerns on the results of MAT, and to describe the technical tips and pitfalls so as to successful clinical results. PMID:22977790

  15. The neuroaesthetics of prose fiction: pitfalls, parameters and prospects.

    PubMed

    Burke, Michael

    2015-01-01

    There is a paucity of neuroaesthetic studies on prose fiction. This is in contrast to the very many impressive studies that have been conducted in recent times on the neuroaesthetics of sister arts such as painting, music and dance. Why might this be the case, what are its causes and, of greatest importance, how can it best be resolved? In this article, the pitfalls, parameters and prospects of a neuroaesthetics of prose fiction will be explored. The article itself is part critical review, part methodological proposal and part opinion paper. Its aim is simple: to stimulate, excite and energize thinking in the discipline as to how prose fiction might be fully integrated in the canon of neuroaesthetics and to point to opportunities where neuroimaging studies on literary discourse processing might be conducted in collaborative work bringing humanists and scientists together.

  16. Visual, Physiological, and Aesthetic Factors and Pitfalls in Asian Blepharoplasty

    PubMed Central

    Chen, William Pai-Dei

    2016-01-01

    Double eyelid surgery to create an upper-lid crease in Asian patients is one of the more popular aesthetic surgeries among people of Asian descent. Much has been written about the myriad methods, but little has been written about the underlying factors that predispose a patient to complications and suboptimal results. This article touches on some of the possible errors in placement of crease height in upper blepharoplasty and the pitfalls that can be associated with permanent placement of nondissolvable sutures that encircle the complex layers of the upper eyelid, as well as the ideal eyelid crease wound closure and its biodynamics. One should consider these factors in any form of upper eyelid procedure, as they are not merely applicable to upper blepharoplasty. PMID:26673576

  17. Artifacts and pitfalls in MR imaging of the pelvis.

    PubMed

    Zand, Khashayar Rafat; Reinhold, Caroline; Haider, Masoom A; Nakai, Asako; Rohoman, Laurian; Maheshwari, Sharad

    2007-09-01

    Artifacts are intimately intertwined with MRI. For the practicing radiologist, effective supervision, troubleshooting, and interpretation of diagnostic MR studies require a solid knowledge of the pertinent artifacts. This article seeks to familiarize the reader with commonly encountered artifacts and pitfalls in pelvic imaging, the mechanism behind their generation, and methods of minimizing their negative impact or maximizing their diagnostic yield. It also serves as an exciting tool to learn many aspects of basic and advanced MR physics. Artifacts are categorized into patient- and sequence-related artifacts. Various manifestations of motion and vascular artifacts, susceptibility, altered tissue contrast, blurring, chemical shift artifact, volume averaging, and gadolinium (Gd) pseudolayering are explained, along with their proposed remedies.

  18. Avoiding the pitfalls of adaptive management implementation in Swedish silviculture.

    PubMed

    Rist, Lucy; Felton, Adam; Mårald, Erland; Samuelsson, Lars; Lundmark, Tomas; Rosvall, Ola

    2016-02-01

    There is a growing demand for alternatives to Sweden's current dominant silvicultural system, driven by a desire to raise biomass production, meet environmental goals and mitigate climate change. However, moving towards diversified forest management that deviates from well established silvicultural practices carries many uncertainties and risks. Adaptive management is often suggested as an effective means of managing in the context of such complexities. Yet there has been scepticism over its appropriateness in cases characterised by large spatial extents, extended temporal scales and complex land ownership-characteristics typical of Swedish forestry. Drawing on published research, including a new paradigm for adaptive management, we indicate how common pitfalls can be avoided during implementation. We indicate the investment, infrastructure, and considerations necessary to benefit from adaptive management. In doing so, we show how this approach could offer a pragmatic operational model for managing the uncertainties, risks and obstacles associated with new silvicultural systems and the challenges facing Swedish forestry.

  19. Multi-criteria decision analysis: Limitations, pitfalls, and practical difficulties

    SciTech Connect

    Kujawski, Edouard

    2003-02-01

    The 2002 Winter Olympics women's figure skating competition is used as a case study to illustrate some of the limitations, pitfalls, and practical difficulties of Multi-Criteria Decision Analysis (MCDA). The paper compares several widely used models for synthesizing the multiple attributes into a single aggregate value. The various MCDA models can provide conflicting rankings of the alternatives for a common set of information even under states of certainty. Analysts involved in MCDA need to deal with the following challenging tasks: (1) selecting an appropriate analysis method, and (2) properly interpreting the results. An additional trap is the availability of software tools that implement specific MCDA models that can beguile the user with quantitative scores. These conclusions are independent of the decision domain and they should help foster better MCDA practices in many fields including systems engineering trade studies.

  20. Merits and Pitfalls of Currently Used Diagnostic Tools in Mycetoma

    PubMed Central

    van de Sande, Wendy W. J.; Fahal, Ahmed H.; Goodfellow, Michael; Mahgoub, El Sheikh; Welsh, Oliverio; Zijlstra, Ed E.

    2014-01-01

    Treatment of mycetoma depends on the causative organism and since many organisms, both actinomycetes (actinomycetoma) and fungi (eumycetoma), are capable of producing mycetoma, an accurate diagnosis is crucial. Currently, multiple diagnostic tools are used to determine the extent of infections and to identify the causative agents of mycetoma. These include various imaging, cytological, histopathological, serological, and culture techniques; phenotypic characterisation; and molecular diagnostics. In this review, we summarize these techniques and identify their merits and pitfalls in the identification of the causative agents of mycetoma and the extent of the disease. We also emphasize the fact that there is no ideal diagnostic tool available to identify the causative agents and that future research should focus on the development of new and reliable diagnostic tools. PMID:24992636

  1. Merits and pitfalls of currently used diagnostic tools in mycetoma.

    PubMed

    van de Sande, Wendy W J; Fahal, Ahmed H; Goodfellow, Michael; Mahgoub, El Sheikh; Welsh, Oliverio; Zijlstra, Ed E

    2014-07-01

    Treatment of mycetoma depends on the causative organism and since many organisms, both actinomycetes (actinomycetoma) and fungi (eumycetoma), are capable of producing mycetoma, an accurate diagnosis is crucial. Currently, multiple diagnostic tools are used to determine the extent of infections and to identify the causative agents of mycetoma. These include various imaging, cytological, histopathological, serological, and culture techniques; phenotypic characterisation; and molecular diagnostics. In this review, we summarize these techniques and identify their merits and pitfalls in the identification of the causative agents of mycetoma and the extent of the disease. We also emphasize the fact that there is no ideal diagnostic tool available to identify the causative agents and that future research should focus on the development of new and reliable diagnostic tools.

  2. The Head-fixed Behaving Rat—Procedures and Pitfalls

    PubMed Central

    Schwarz, Cornelius; Hentschke, Harald; Butovas, Sergejus; Haiss, Florent; Stüttgen, Maik C; Gerdjikov, Todor V; Bergner, Caroline G; Waiblinger, Christian

    2010-01-01

    This paper describes experimental techniques with head-fixed, operantly conditioned rodents that allow the control of stimulus presentation and tracking of motor output at hitherto unprecedented levels of spatio-temporal precision. Experimental procedures for the surgery and behavioral training are presented. We place particular emphasis on potential pitfalls using these procedures in order to assist investigators who intend to engage in this type of experiment. We argue that head-fixed rodent models, by allowing the combination of methodologies from molecular manipulations, intracellular electrophysiology, and imaging to behavioral measurements, will be instrumental in combining insights into the functional neuronal organization at different levels of observation. Provided viable behavioral methods are implemented, model systems based on rodents will be complementary to current primate models—the latter providing highest comparability with the human brain, while the former offer hugely advanced methodologies on the lower levels of organization, for example, genetic alterations, intracellular electrophysiology, and imaging. PMID:20954892

  3. Keratinocyte-based cell assays: their potential pitfalls.

    PubMed

    Zupancic, Tina; Ozir, Mateja; Törmä, Hans; Komel, Radovan; Liovic, Mirjana

    2012-11-01

    As an in vitro model system, patient-derived epidermolysis bullosa simplex keratinocytes have had an immense impact on what we know today about keratin filament function and their role in disease development. In the absence of gene therapy, screening compound libraries for new or better drugs is another approach to improve existing treatments for genodermatoses. However in this study, we report of the potential pitfalls when using this type of cell lines as a "reporter" system. When cell lines with different genetic backgrounds are being used in cell-based assays, the greatest obstacle is to determine the most appropriate culture conditions (i.e., the composition of medium, number of cells plated and number of days in culture). We demonstrate how culture conditions can greatly interfere with the cellular response in cell-based assays (cell proliferation, metabolic activity and migration), potentially also giving rise to misleading data.

  4. Avoiding common pitfalls in qualitative data collection and transcription.

    PubMed

    Easton, K L; McComish, J F; Greenberg, R

    2000-09-01

    The subjective nature of qualitative research necessitates scrupulous scientific methods to ensure valid results. Although qualitative methods such as grounded theory, phenomenology, and ethnography yield rich data, consumers of research need to be able to trust the findings reported in such studies. Researchers are responsible for establishing the trustworthiness of qualitative research through a variety of ways. Specific challenges faced in the field can seriously threaten the dependability of the data. However, by minimizing potential errors that can occur when doing fieldwork, researchers can increase the trustworthiness of the study. The purpose of this article is to present three of the pitfalls that can occur in qualitative research during data collection and transcription: equipment failure, environmental hazards, and transcription errors. Specific strategies to minimize the risk for avoidable errors will be discussed.

  5. Potential pitfalls of strain rate imaging: angle dependency

    NASA Technical Reports Server (NTRS)

    Castro, P. L.; Greenberg, N. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    Strain Rate Imaging (SRI) is a new echocardiographic technique that allows for the real-time determination of myocardial SR, which may be used for the early and accurate detection of coronary artery disease. We sought to study whether SR is affected by scan line alignment in a computer simulation and an in vivo experiment. Through the computer simulation and the in vivo experiment we generated and validated safe scanning sectors within the ultrasound scan sector and showed that while SRI will be an extremely valuable tool in detecting coronary artery disease there are potential pitfalls for the unwary clinician. Only after accounting for these affects due to angle dependency, can clinicians utilize SRI's potential as a valuable tool in detecting coronary artery disease.

  6. Global temperature evolution: recent trends and some pitfalls

    NASA Astrophysics Data System (ADS)

    Rahmstorf, Stefan; Foster, Grant; Cahill, Niamh

    2017-05-01

    Global surface temperatures continue to rise. In most surface temperature data sets, the years 2014, 2015 and again 2016 set new global heat records since the start of regular measurements. Never before have three record years occurred in a row. We show that this recent streak of record heat does not in itself provide statistical evidence for an acceleration of global warming, nor was it preceded by a ‘slowdown period’ with a significantly reduced rate of warming. Rather, the data are fully consistent with a steady global warming trend since the 1970s, superimposed with random, stationary, short-term variability. All recent variations in short-term trends are well within what was to be expected, based on the observed warming trend and the observed variability from the 1970s up to the year 2000. We discuss some pitfalls of statistical analysis of global temperatures which have led to incorrect claims of an unexpected or significant warming slowdown.

  7. Diagnostic pitfalls in spine surgery: masqueraders of surgical spine disease.

    PubMed

    Walcott, Brian P; Coumans, Jean-Valery C E; Kahle, Kristopher T

    2011-10-01

    Disorders of the spine are common in clinical medicine, and spine surgery is being performed with increasing frequency in the US. Although many patients with an established diagnosis of a true surgically treatable lesion are referred to a neurosurgeon, the evaluation of patients with spinal disorders can be complex and fraught with diagnostic pitfalls. While "common conditions are common," astute clinical acumen and vigilance are necessary to identify lesions that masquerade as surgically treatable spine disease that can lead to erroneous diagnosis and treatment. In this review, the authors discuss musculoskeletal, peripheral nerve, metabolic, infectious, inflammatory, and vascular conditions that mimic the syndromes produced by surgical lesions. It is possible that nonsurgical and surgical conditions coexist at times, complicating treatment plans and natural histories. Awareness of these diagnoses can help reduce diagnostic error, thereby avoiding the morbidity and expense associated with an unnecessary operation.

  8. The neuroaesthetics of prose fiction: pitfalls, parameters and prospects

    PubMed Central

    Burke, Michael

    2015-01-01

    There is a paucity of neuroaesthetic studies on prose fiction. This is in contrast to the very many impressive studies that have been conducted in recent times on the neuroaesthetics of sister arts such as painting, music and dance. Why might this be the case, what are its causes and, of greatest importance, how can it best be resolved? In this article, the pitfalls, parameters and prospects of a neuroaesthetics of prose fiction will be explored. The article itself is part critical review, part methodological proposal and part opinion paper. Its aim is simple: to stimulate, excite and energize thinking in the discipline as to how prose fiction might be fully integrated in the canon of neuroaesthetics and to point to opportunities where neuroimaging studies on literary discourse processing might be conducted in collaborative work bringing humanists and scientists together. PMID:26283953

  9. Archival-grade optical disc design and international standards

    NASA Astrophysics Data System (ADS)

    Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo

    2015-09-01

    Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.

  10. Herbal hepatotoxicity: challenges and pitfalls of causality assessment methods.

    PubMed

    Teschke, Rolf; Frenzel, Christian; Schulze, Johannes; Eickhoff, Axel

    2013-05-21

    The diagnosis of herbal hepatotoxicity or herb induced liver injury (HILI) represents a particular clinical and regulatory challenge with major pitfalls for the causality evaluation. At the day HILI is suspected in a patient, physicians should start assessing the quality of the used herbal product, optimizing the clinical data for completeness, and applying the Council for International Organizations of Medical Sciences (CIOMS) scale for initial causality assessment. This scale is structured, quantitative, liver specific, and validated for hepatotoxicity cases. Its items provide individual scores, which together yield causality levels of highly probable, probable, possible, unlikely, and excluded. After completion by additional information including raw data, this scale with all items should be reported to regulatory agencies and manufacturers for further evaluation. The CIOMS scale is preferred as tool for assessing causality in hepatotoxicity cases, compared to numerous other causality assessment methods, which are inferior on various grounds. Among these disputed methods are the Maria and Victorino scale, an insufficiently qualified, shortened version of the CIOMS scale, as well as various liver unspecific methods such as the ad hoc causality approach, the Naranjo scale, the World Health Organization (WHO) method, and the Karch and Lasagna method. An expert panel is required for the Drug Induced Liver Injury Network method, the WHO method, and other approaches based on expert opinion, which provide retrospective analyses with a long delay and thereby prevent a timely assessment of the illness in question by the physician. In conclusion, HILI causality assessment is challenging and is best achieved by the liver specific CIOMS scale, avoiding pitfalls commonly observed with other approaches.

  11. Big data in sleep medicine: prospects and pitfalls in phenotyping

    PubMed Central

    Bianchi, Matt T; Russo, Kathryn; Gabbidon, Harriett; Smith, Tiaundra; Goparaju, Balaji; Westover, M Brandon

    2017-01-01

    Clinical polysomnography (PSG) databases are a rich resource in the era of “big data” analytics. We explore the uses and potential pitfalls of clinical data mining of PSG using statistical principles and analysis of clinical data from our sleep center. We performed retrospective analysis of self-reported and objective PSG data from adults who underwent overnight PSG (diagnostic tests, n=1835). Self-reported symptoms overlapped markedly between the two most common categories, insomnia and sleep apnea, with the majority reporting symptoms of both disorders. Standard clinical metrics routinely reported on objective data were analyzed for basic properties (missing values, distributions), pairwise correlations, and descriptive phenotyping. Of 41 continuous variables, including clinical and PSG derived, none passed testing for normality. Objective findings of sleep apnea and periodic limb movements were common, with 51% having an apnea–hypopnea index (AHI) >5 per hour and 25% having a leg movement index >15 per hour. Different visualization methods are shown for common variables to explore population distributions. Phenotyping methods based on clinical databases are discussed for sleep architecture, sleep apnea, and insomnia. Inferential pitfalls are discussed using the current dataset and case examples from the literature. The increasing availability of clinical databases for large-scale analytics holds important promise in sleep medicine, especially as it becomes increasingly important to demonstrate the utility of clinical testing methods in management of sleep disorders. Awareness of the strengths, as well as caution regarding the limitations, will maximize the productive use of big data analytics in sleep medicine. PMID:28243157

  12. Designing sensory-substitution devices: Principles, pitfalls and potential1

    PubMed Central

    Kristjánsson, Árni; Moldoveanu, Alin; Jóhannesson, Ómar I.; Balan, Oana; Spagnol, Simone; Valgeirsdóttir, Vigdís Vala; Unnthorsson, Rúnar

    2016-01-01

    An exciting possibility for compensating for loss of sensory function is to augment deficient senses by conveying missing information through an intact sense. Here we present an overview of techniques that have been developed for sensory substitution (SS) for the blind, through both touch and audition, with special emphasis on the importance of training for the use of such devices, while highlighting potential pitfalls in their design. One example of a pitfall is how conveying extra information about the environment risks sensory overload. Related to this, the limits of attentional capacity make it important to focus on key information and avoid redundancies. Also, differences in processing characteristics and bandwidth between sensory systems severely constrain the information that can be conveyed. Furthermore, perception is a continuous process and does not involve a snapshot of the environment. Design of sensory substitution devices therefore requires assessment of the nature of spatiotemporal continuity for the different senses. Basic psychophysical and neuroscientific research into representations of the environment and the most effective ways of conveying information should lead to better design of sensory substitution systems. Sensory substitution devices should emphasize usability, and should not interfere with other inter- or intramodal perceptual function. Devices should be task-focused since in many cases it may be impractical to convey too many aspects of the environment. Evidence for multisensory integration in the representation of the environment suggests that researchers should not limit themselves to a single modality in their design. Finally, we recommend active training on devices, especially since it allows for externalization, where proximal sensory stimulation is attributed to a distinct exterior object. PMID:27567755

  13. Herbal hepatotoxicity: Challenges and pitfalls of causality assessment methods

    PubMed Central

    Teschke, Rolf; Frenzel, Christian; Schulze, Johannes; Eickhoff, Axel

    2013-01-01

    The diagnosis of herbal hepatotoxicity or herb induced liver injury (HILI) represents a particular clinical and regulatory challenge with major pitfalls for the causality evaluation. At the day HILI is suspected in a patient, physicians should start assessing the quality of the used herbal product, optimizing the clinical data for completeness, and applying the Council for International Organizations of Medical Sciences (CIOMS) scale for initial causality assessment. This scale is structured, quantitative, liver specific, and validated for hepatotoxicity cases. Its items provide individual scores, which together yield causality levels of highly probable, probable, possible, unlikely, and excluded. After completion by additional information including raw data, this scale with all items should be reported to regulatory agencies and manufacturers for further evaluation. The CIOMS scale is preferred as tool for assessing causality in hepatotoxicity cases, compared to numerous other causality assessment methods, which are inferior on various grounds. Among these disputed methods are the Maria and Victorino scale, an insufficiently qualified, shortened version of the CIOMS scale, as well as various liver unspecific methods such as the ad hoc causality approach, the Naranjo scale, the World Health Organization (WHO) method, and the Karch and Lasagna method. An expert panel is required for the Drug Induced Liver Injury Network method, the WHO method, and other approaches based on expert opinion, which provide retrospective analyses with a long delay and thereby prevent a timely assessment of the illness in question by the physician. In conclusion, HILI causality assessment is challenging and is best achieved by the liver specific CIOMS scale, avoiding pitfalls commonly observed with other approaches. PMID:23704820

  14. Treatment of lumbar disc herniation by percutaneous laser disc decompression (PLDD) and modified PLDD

    NASA Astrophysics Data System (ADS)

    Chi, Xiao fei; Li, Hong zhi; Wu, Ru zhou; Sui, Yun xian

    2005-07-01

    Objective: To study the micro-invasive operative method and to compare the effect of treatment of PLDD and modified PLDD for Lumbar Disc Herniation. Method: Vaporized part of the nucleus pulposus in single or multiple point after acupuncture into lumbar disc, to reach the purpose of the decompression of the lumbar disc. Result: Among the 19 cases of the regular PLDD group, the excellent and good rate was 63.2%, and among the 40 cases of the modified PLDD group, the excellent and good rate was 82.5%. Conclusion: The modified PLDD has good effect on the treatment for lumbar disc herniation.

  15. [Disc electrophoresis of collagen protein (author's transl)].

    PubMed

    Reitmayr, P; Verzár, F

    1975-01-01

    The composition of proteins extracted from tendon collagen is investigated by disc electrophoresis. No qualitative differences can be demonstrated between young and old collagen. The action of formaldehyde and methionine on the tendons has no effect on the electrophoretic picture.

  16. Thermal analysis on motorcycle disc brake geometry

    NASA Astrophysics Data System (ADS)

    W. M. Zurin W., S.; Talib, R. J.; Ismail, N. I.

    2017-08-01

    Braking is a phase of slowing and stop the movement of motorcycle. During braking, the frictional heat was generated and the energy was ideally should be faster dissipated to surrounding to prevent the built up of the excessive temperature which may lead to brake fluid vaporization, thermoelastic deformation at the contact surface, material degradation and failure. In this paper, solid and ventilated type of motorcycle disc brake are being analyse using Computational Fluid Dynamic (CFD) software. The main focus of the analysis is the thermal behaviour during braking for solid and ventilated disc brake. A comparison between both geometries is being discussed to determine the better braking performance in term of temperature distribution. It is found that ventilated disc brake is having better braking performance in terms of heat transfer compare to solid disc.

  17. Genetics Home Reference: intervertebral disc disease

    MedlinePlus

    ... link) National Institute of Neurological Disorders and Stroke: Low Back Pain Fact Sheet Educational Resources (8 links) American Association ... MalaCards: intervertebral disc disease Merck Manual Consumer Version: Low Back Pain Merck Manual Consumer Version: Neck Pain The Children's ...

  18. Dynamical modelling of galactic disc outskirts

    NASA Astrophysics Data System (ADS)

    Athanassoula, E.

    2017-03-01

    I review briefly some dynamical models of structures in the outer parts of disc galaxies, including models of polar rings, tidal tails and bridges. I then discuss the density distribution in the outer parts of discs. For this, I compare observations to results of a model in which the disc galaxy is in fact the remnant of a major merger, and find good agreement. This comparison includes radial profiles of the projected surface density and of stellar age, as well as time evolution of the break radius and of the inner and outer disc scale lengths. I also compare the radial projected surface density profiles of dynamically motivated mono-age populations and find that, compared to older populations, younger ones have flatter density profiles in the inner region and steeper in the outer one. The break radius, however, does not vary with stellar age, again in good agreement with observations.

  19. Particle rings and astrophysical accretion discs

    SciTech Connect

    Lovelace, R. V. E. Romanova, M. M.

    2016-03-25

    Norman Rostoker had a wide range of interests and significant impact on the plasma physics research at Cornell during the time he was a Cornell professor. His interests ranged from the theory of energetic electron and ion beams and strong particle rings to the related topics of astrophysical accretion discs. We outline some of the topics related to rings and discs including the Rossby wave instability which leads to formation of anticyclonic vortices in astrophysical discs. These vorticies are regions of high pressure and act to trap dust particles which in turn may facilitate planetesimals growth in proto-planetary disks and could be important for planet formation. Analytical methods and global 3D magneto-hydrodynamic simulations have led to rapid advances in our understanding of discs in recent years.

  20. A biphasic finite element model of in vitro plowing tests of the temporomandibular joint disc.

    PubMed

    Spilker, R L; Nickel, J C; Iwasaki, L R

    2009-06-01

    Disorders of the temporomandibular joint (TMJ) afflict 3-29% of people aged 19-40 years. Degenerative joint disease (DJD) of the TMJ generally occurs 15 years earlier than in other human joints and 1.5-2 times more often in women than men. The TMJ disc is the primary stress distribution mechanism within the joint. Mechanical failure of the TMJ disc precedes clinical signs of DJD. Unlike postcranial synovial joints, biomimetic replacements of the disc have not been successful, probably due to the paucity of knowledge about TMJ biomechanics. Translation of stress-fields mediolaterally across the TMJ disc may lead to fatigue failure because of the effect of traction forces on the tissue surface and because the disc is relatively weak in this aspect. Traction forces are composed of friction forces, which are known to be low in the TMJ, and plowing forces which are relatively much higher and result from movement and pressurization of fluids within the tissues due to translating surface loads. In the in vitro plowing experiment, a rigid curve-ended indenter is lowered into a TMJ disc that has been mounted on a stage with pressure gauges, and the indenter is then translated in a prescribed mediolateral motion that is intended to simulate the motion of the mandibular condyle on the TMJ disc in vivo. As a first step, these plowing experiments have quantified the variables thought to be important in tissue failure. A next step is to define the full role of these variables in the pathomechanics of TMJ disc tissue through a validated model. Therefore, the aim of this study was to develop and test a finite element model of the plowing experiments based on an orthotropic biphasic description of the soft tissue behavior of the TMJ disc. For this plowing model, the arbitrary Lagrange Eulerian method was used to approximate the moving load problem, where in vitro the indenter slid along the tissue's superior surface. Approximate validation of the plowing model was based on