Two-stage reconstruction using an antibiotic loaded cement spacer is the preferred treatment method of late hip joint infections. Hip spacers maintain stability of the joint and length of the limb during treatment period. However, as the material strength of bone cement (PMMA) is limited, spacer fractures led to serious complications in the past. This study investigated the load capacity of custom made hip spacers, developed at the 'Klinik für Orthopädie und Orthopädische Chirurgie' (Universitätsklinikum des Saarlandes, Homburg / Saar, Germany), and implanted into composite femurs. In a quasi-static test, non-reinforced spacers tolerated hip joint loads of about 3000 N, whereas reinforced spacers with titanium-grade-two endoskeletons doubled this load up to 6000 N. Even for cyclic loading, endoskeleton-including hip spacers tolerated loads of >4500 N with 500,000 load cycles. Thus, an endoskeleton-including spacer should provide a mobile and functional joint through the treatment course. A generated FE-model was used to determine the fracture stresses and allows for further sensitivity analysis.
Thielen, T.; Maas, S.; Zuerbes, A.; Waldmann, D.; Anagnostakos, K.; Kelm, J.
Infection after total hip arthroplasties (THA) is a devastating complication with significant consequences for both the patients and the healthcare systems. In recent times, a two stage procedure using antibiotic-impregnated interim spacers has become the most popular treatment for late chronic hip joint infections after THA with success rates over 90%. In this review, we discuss the different types of
Mohamed Sukeik; Fares S. Haddad
Within the first two years after total hip arthroplasty implant-associated infection has become the second most common reason for a revision surgery. Two-stage implant exchange is frequently conducted using temporary spacers made of antibiotic-loaded cement in order to prevent a bacterial colonization on the spacer. Avoiding several disadvantages of cement spacers, a conventional hemi-endoprosthesis was equipped with a copper-containing implant coating for inhibition of bacterial biofilms. In the present paper details of this novel treatment concept are presented including a case report.
Ellenrieder, Martin; Haenle, Maximilian; Lenz, Robert; Bader, Rainer; Mittelmeier, Wolfram
Composites are made of two or more different components that combine their properties into a new material. By modifying the type or structure or volume of the components, a theoretically endless number of new materials can be produced and their properties can be altered as desired. A composite hip implant made of carbon fiber and polysulfone is described. PMID:3405625
Mendes, D G; Roffman, M; Soudry, M; Angel, D; Boss, J; Charit, Y; Rotem, A; Hunt, M; Mordechovitch, D
Background Articulating spacers used in two-stage revision surgery of infected prostheses have the potential to abrade and subsequently\\u000a induce third-body wear of the new prosthesis.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes We asked whether particulate material abraded from spacers could be detected in the synovial membrane 6 weeks after implantation\\u000a when the spacers were removed for the second stage of the revision.\\u000a \\u000a \\u000a \\u000a \\u000a Patients and Methods Sixteen hip spacers (cemented
Bernd Fink; Annett Rechtenbach; Hubert Büchner; Sebastian Vogt; Michael Hahn
Hip fractures are associated with significant mortality and morbidity for the patients, more dependent residual status, and increased socio-economic cost. Many hip-fracture patients experience severe functional impairment, and most never recover their pre-fracture level of function. Current research has sought to identify the most effective treatments to reduce the incidence of hip fractures, improve survival and quality of life, and minimize complications and disability. The treatment of these fractures in the elderly aims to return these people to their pre-fracture mobility and functional level. This article reviews the surgical treatment options for extracapsular hip fractures and discusses their associated advantages, disadvantages, and complications. Two types of implants are currently available: the dynamic hip screw (DHS), and the intramedullary hip nail with one or two sliding screws. In this review, no clear advantage of one implant over another for the treatment of extracapsular hip fractures was evident. Both the DHS and hip nails can be used successfully for the treatment of stable hip fractures; for unstable fractures and low subtrochanteric fractures, hip nails are preferred. Although hip nails are associated with limited exposure, lower blood loss and transfusion requirements, and shorter operative time, complications are more common with hip nails. Long-term survival and function are similar in the two approaches. Hip nails with two sliding screws do not seem to make the difference in clinical practice that is reported in biomechanical studies. PMID:23016784
Mavrogenis, Andreas F; Kouvidis, George; Stavropoulos, Nikolaos A; Stavrakakis, Loannis; Katonis, Pavlos; Papagelopoulos, Panayiotis J
Deep infection of a joint endoprosthesis constitutes a threat to the stability of the implant and joint function. It requires a comprehensive and interdisciplinary approach, involving the joint revision and removal of the bacterial biofilm from all tissues, the endoprosthesis must be often removed and bone stock infection treated. The paper presents the author's experience with the use of acrylic cement spacers, custom-made during the surgery and containing low dose of an antibiotic supplemented with 5% of a selected, targeted antibiotic for the infection of hip and knee endoprostheses. 33 two-stage revisions of knee and hip joints with the use of a spacer were performed. They involved 24 knee joints and 9 hip joints. The infections were mostly caused by staphylococci MRSA (18) and MSSA (8), and in some cases Enterococci (4), Salmonella (1), Pseudomonas (1) and Acinetobacter (1). The infection was successfully treated in 31 out of 33 cases (93.93%), including 8 patients with the hip infection and 23 patients with the knee infection. The endoprosthesis was reimplanted in 30 cases: for 7 hips and 23 knees, in 3 remaining cases the endoprosthesis was not reimplanted. Mechanical complications due to the spacer occurred in 4 cases: 3 dislocations and 1 fracture (hip spacer). The patients with hip spacers were ambulatory with a partial weight bearing of the operated extremity and those with knee spacers were also ambulatory with a partial weight bearing, but the extremity was initially protected by an orthosis. The spacer enables to maintain a limb function, and making it by hand allows the addition of the specific bacteria targeted antibiotic thus increasing the likelihood of the effective antibacterial treatment. PMID:23306284
Introduction. Total hip arthroplasty (THA) infections with severe bone loss pose significant reconstructive challenges. We present our experience with two-stage hip reimplantation using an intramedullary, antibiotic-impregnated nail. Methods. Three patients with infected THA with severe proximal femoral bone loss (Mallory type IIIB or greater) were treated using a custom antibiotic spacer. Clinical outcomes and any complications were recorded. Average followup was 49 months from final reimplantation. Results. Mean age at spacer placement (stage 1) was 53 years. The mean Harris Hip Score at final followup was 80. Two patients had asymptomatic heterotopic ossification, and one patient had a 2 cm leg-length discrepancy. Conclusions. A custom intramedullary nail antibiotic spacer is a reliable option in the staged management of the infected THA with severe proximal femoral bone loss. Benefits of this technique include limb salvage with maintenance of leg length, soft tissue tension, and functional status.
Kamath, Atul F.; Anakwenze, Okechukwu; Lee, Gwo-Chin; Nelson, Charles L.
This Technology Overview was prepared using systematic review methodology and summarizes the findings of studies published as of July 15, 2011, on modern metal-on-metal hip implants. Analyses conducted on outcomes by two joint registries indicate that patients who receive metal-on-metal total hip arthroplasty (THA) and hip resurfacing are at greater risk for revision than are patients who receive THA using a different bearing surface combination. Data from these registries also indicate that larger femoral head components have higher revision rates and risk of revision and that older age is associated with increased revision risks of large-head metal-on-metal THA. Several studies noted a correlation between suboptimal hip implant positioning and higher wear rates, local metal debris release, and consequent local tissue reactions to metal debris. In addition, several studies reported elevated serum metal ion concentrations in patients with metal-on-metal hip articulations, although the clinical significance of these elevated ion concentrations remains unknown. PMID:22661570
Bozic, Kevin J; Browne, James; Dangles, Chris J; Manner, Paul A; Yates, Adolph J; Weber, Kristy L; Boyer, Kevin M; Zemaitis, Paul; Woznica, Anne; Turkelson, Charles M; Wies, Janet L
A review of wear mechanisms has been carried out in this paper for the hip prostheses. The primary causes of premature failure in hip prostheses are due to wearing of the implants. Multiple variables interact and increase the resultant wear rates. A summary of clinical in vivo and bulk material wear rate data from published literature has been presented for
A Buford; T Goswami
Recently, there has been a rapid increase in the number of hip arthroscopies performed. The increase in the number of primary surgeries has been associated with a similar increase in the number of revision procedures. The most frequent indications for revision hip arthroscopy are residual bony deformity (impingement), persistent labral pathology, and intra-articular adhesions. Our current understanding of capsulolabral adhesions is limited. Although adhesions between the capsule and labrum are common after hip arthroscopy, generally, they are mild and asymptomatic. However, in severe cases they may cause persistent synovitis and pain, and they may tether the labrum away from the femoral head, causing loss of the suction-seal effect. Such patients present with nonspecific symptoms such as persistent pain, giving way, catching, and pain in hip flexion. Magnetic resonance imaging can aid in the diagnosis by showing the absence of liquid in the capsulolabral recess, although the definitive diagnosis is based on dynamic arthroscopic evaluation. We present our approach to the lysis of capsulolabral adhesions with preservation of labral tissue and describe a technique that uses an iliotibial band allograft to prevent recurrence of such adhesions by maintaining space between the capsule and labrum.
Philippon, Marc J.; Ferro, Fernando P.; Nepple, Jeffrey J.
Synthetic femurs were used to assess the initial bone-implant interface stability of three total hip systems: Wright Medical Technology's Infinity smooth trochanteric module (S-TM), Infinity porous-coated trochanteric module (PC-TM), and Johnson and Johnson S-ROM with a porous surface. The hips were implanted into synthetic femurs, rigidly fixed, and subjected to internal rotation and cyclic, axial compressive loads. The results showed that all three implants achieved good initial implant stability and would be expected to permit bone ingrowth. The porous-coated implants showed greater initial implant stability with less axial micromotion compared with the smooth implants. This finding suggests that surface texture plays a role in initial stability of uncemented prostheses if the bone behaves similar to the material used in this study. PMID:9731670
Lee, T Q; Danto, M I; Kim, W C
Because younger, more active patients are receiving total hip replacements, it is necessary to develop materials, which would increase the life span of the implants and challenge their wear potential under adverse conditions. Oxidized zirconium (OxZr) is a metal with the surface transformed to ceramic by oxidation that offers low fracture risk and excellent abrasion resistance. This study compared wear
V. Good; K. Widding; G. Hunter; D. Heuer
This paper is aimed at determining the number of screws and the dimensions of the appliance components of a hip nail-plate screw implant such that their sizes are a minimum (i.e. the implant weight is minimum), without the stresses in the appliance components as well as in the bone shaft exceeding the allowable limits. The implant-bone structure is idealized as a hybrid frame, composed of appliance components and the supporting femur bone elements, which act integrally to support the maximal load (during the gait cycle) at the hip joint. For various configurations of the implant, entailing different numbers of screws, the optimization technique is employed to determine the size of the members (nail, plate and screws) for a lightweight design. Implant configurations are analyzed for two, three, four and five nail configurations. The analysis of the hybrid (implant femur) frame, during each integrative object function and design parameter evaluation, is done by the Finite Element Method. The optimization problem is solved by the sequential unconstrained minimization technique (with the introduction of interior penalty function terms). It is found, from the results of analyses of the four hybrid frames, that the appliance frame, with two screws, yields the minimum-weight structurally safe design. PMID:8925648
Elkholy, A H
A 39-year-old female with elevated serum cobalt levels from her bilateral hip prostheses presented with a 3-week history of blurred vision in her left eye. Optical coherence tomography revealed patchy degeneration of the photoreceptor-retinal pigment epithelium (RPE) complex. The lesions were hypofluorescent on indocyanine green angiography. We postulate that this is a case of implant-related chorio-retinal cobalt toxicity.
Ng, Soo K; Ebneter, Andreas; Gilhotra, Jagjit S
We report the outcome at ten to 15 years of two-stage revision for hip infection in 99 patients using the Prostalac articulated hip spacer system. All the patients were contacted to determine their current functional and infection status using the Oxford-12, Short form-12, and Western Ontario and McMaster University Osteoarthritis Index questionnaires. A total of 11 of the 99 patients had a further infection, of whom seven responded to repeat surgery with no further sequelae. The mean interval between the stages was five months (1 to 36). We were able to review 48 living patients, with a mean age of 72 years (46 to 86), 34 (71%) of whom provided health-related quality-of-life outcome scores. The mean follow-up was 12 years (10 to 15). The long-term success rate was 89% and with additional surgery this rose to 96%. The mean global Western Ontario and McMaster University Osteoarthritis Index score was 80.6 (sd 18.3). The mean Oxford-12 score was 74.0 (sd 22.3), and the mean Short form-12 score was 53.1 (sd 9.4) (mental) and 33.5 (sd 13.5) (physical). The mean satisfaction score was 90.5 (sd 15.3). Two-stage revision for hip infection using a Prostalac interim spacer offers a predictable and lasting solution for patients with this difficult problem. PMID:19880885
Biring, G S; Kostamo, T; Garbuz, D S; Masri, B A; Duncan, C P
\\u000a Pseudotumours (soft-tissue masses relating to the hip joint) following metal-on-metal hip resurfacing arthroplasty (MoMHRA)\\u000a have been associated with elevated serum and hip aspirate metal ion levels, suggesting that pseudotumours occur when there\\u000a is increased wear. We aimed to quantify in vivo wear of implants revised for pseudotumours (8) and a control group of implants\\u000a (22) revised for other reasons of
Young-Min Kwon; Harinderjit S. Gill; David W. Murray; Amir Kamali
We present a rare case of an immunocompetent host who developed a Candida albicans-infected total hip prosthesis. The infection could not be eradicated with debridement and extensive antifungal therapy. Our patient first underwent a resection of the proximal femur and local treatment with gentamicin-loaded cement beads. In a second procedure, a handmade cement spacer impregnated with voriconazole, amphotericin B, and vancomycin was placed. After 3 months of additional systemic antibiotic therapy, the patient remained afebrile, and a tumor prosthesis was placed. Six years postoperatively, she is doing well, walking with a small limp and no signs of recurrent infection. This is the first report on elution of voriconazole and amphotericin B from bone cement delivered at clinically significant concentrations for at least 72 hours. PMID:22810009
Deelstra, Jenneke J; Neut, Danielle; Jutte, Paul C
Advances in surgical technique and implant technology have improved the ten-year survival after primary total hip arthroplasty (THA). Despite this, the number of revision procedures has been increasing in recent years, a trend which is predicted to continue into the future. Revision THA is a technically demanding procedure often complicated by a loss of host bone stock which may be compounded by the need to remove primary implants. Both cemented and uncemented implant designs are commonly used in the United Kingdom for primary and revision THA and much controversy still exists as to the ideal method of stem fixation. In this article we discuss revision of the femur using cemented components during revision THA. We focus on three clinical scenarios including femoral cement-in-cement revision where the primary femoral cement-bone interface remains well fixed, femoral cement-in-cement revision for peri-prosthetic femoral fractures, and femoral impaction grafting. We discuss the clinical indications, surgical techniques and clinical outcomes for each of these procedures. PMID:21165618
Holt, Graeme; Hook, Samantha; Hubble, Matthew
Advances in surgical technique and implant technology have improved the ten-year survival after primary total hip arthroplasty (THA). Despite this, the number of revision procedures has been increasing in recent years, a trend which is predicted to continue into the future. Revision THA is a technically demanding procedure often complicated by a loss of host bone stock which may be compounded by the need to remove primary implants. Both cemented and uncemented implant designs are commonly used in the United Kingdom for primary and revision THA and much controversy still exists as to the ideal method of stem fixation. In this article we discuss revision of the femur using cemented components during revision THA. We focus on three clinical scenarios including femoral cement-in-cement revision where the primary femoral cement-bone interface remains well fixed, femoral cement-in-cement revision for peri-prosthetic femoral fractures, and femoral impaction grafting. We discuss the clinical indications, surgical techniques and clinical outcomes for each of these procedures.
Hook, Samantha; Hubble, Matthew
From 1973 to 1976, McKee-Farrar total hip arthroplasties were performed in the Orthopaedics Department at the Centre of Pulmology. In the present study, only patients with a complete record of radiological changes at the bone\\/implant or bone\\/cement interface were evaluated. A series of 81 patients with 100 total hip prostheses in situ according to the Mayo Clinic hip score and
S. Jantsch; P. Zenz; M. Semlitsch; W. Fertschak
There is increasing interest in using surface modification technology to improve the wear properties of titanium alloy and limit articular surface wear of metal and polyethylene components. This report details the in vivo wear performance of titanium nitride coating on a retrieved hip implant obtained postmortem from a low demand patient 1 year after total hip arthroplasty. Analysis of the
Melinda K. Harman; Scott A. Banks; W. Andrew Hodge
BackgroundIn many studies related to the total hip arthroplasty, it has been found that incorrect alignment of the total hip component is one of the major factors influencing mechanical failures. Although various recommendations for cup orientation have been presented, there were few studies that seek to determine a proper orientation of the implants based on the human motion data. The
Byung-Hoon Ko; Yong-San Yoon
steolysis is due to particulate wear debris and is responsible for the long-term failure of total hip replacements. It has stimulated the development of alternative joint surfaces such as metal-on-metal or ceramic-on-ceramic implants. Since 1988 the second-generation metal-on-metal implant Metasul has been used in over 60 000 hips. Analysis of 118 retrieved specimens of the head or cup showed rates
H.-P. Sieber; C. B. Rieker; P. Köttig
Ceramics are used in hip implants and have been found to produce lower wear rates. This paper discusses the advantages and disadvantages of ceramics compared to other implant materials. Different types of ceramics that are being used are reviewed in terms of the wear characteristics, debris released, and their size together with other biological factors. In general, the wear rates
Matthew Slonaker; T. Goswami
Prosthetic dislocation is one of the most common complications after canine hip replacement. The use of dual mobility acetabular components has been shown to reduce the rate of dislocation in first intent hip replacement in human patients who are at high risk for dislocation. In such implants, a mobile polyethylene liner articulates on one side with a metallic acetabular component and on the other side with a metallic prosthetic head. A dual mobility cemented acetabular component has been designed for use in dogs, and is available for use in association with a previously designed modular femoral component. This report describes the characteristics and the procedure for implantation of this implant combination. PMID:23111812
Guillaumot, P; Autefage, A; Palierne, S; Dembour, T; Chancrin, J-L
Nitrogen ion implantation (which considerably hardens the surface of the bearing) may represent one possible method of reducing the wear of metal-on-metal (MOM) hip bearings. Currently there are no ion-implanted MOM bearings used clinically. Therefore a physiological hip simulator test was undertaken using standard test conditions, and the results compared to previous studies using the same methods. N2-ion implantation of high carbon cast Co-Cr-Mo-on-Co-Cr-Mo hip prostheses increased wear by 2-fold during the aggressive running-in phase compared to untreated bearing surfaces, plus showing no wear reductions during steady-state conditions. Although 2 specimens were considered in the current study, it would appear that ion implantation has no clinical benefit for MOM. PMID:15578563
Bowsher, John G; Hussain, Azad; Williams, Paul; Nevelos, Jim; Shelton, Julia C
The clinical and radiographic results of primary cemented total hip arthroplasty performed by a single surgeon, with particular emphasis on the performance of acetabular components implanted with so-called second-generation cement techniques, were studied. Seventy hips with 48 metal-backed and 22 polyethylene acetabular components were followed for a mean of 9 years (range, 5–11.5 years). The clinical results were evaluated using
Brian S. Ziegler; Paul F. Lachiewicz
\\u000a A major challenge for total hip arthroplasty is to minimize wear and osteolysis in young, active patients. Alumina ceramic\\u000a bearings have shown superior wear resistance and lubrication and do not carry the risk of ion release. In a prospective randomized\\u000a study (ABC), 514 hips were implanted. All patients (average age, 53 years) received the same press-fit hydroxyapatite coated\\u000a femoral stem;
B. E. Bierbaum; J. D’Antonio; W. Capello; M. Manley; R. Deshmukh
When walking long distances, hip prostheses heat up due to friction. The influence of articulating materials and lubricating properties of synovia on the final temperatures, as well as any potential biological consequences, are unknown. Such knowledge is essential for optimizing implant materials, identifying patients who are possibly at risk of implant loosening, and proving the concepts of current joint simulators. An instrumented hip implant with telemetric data transfer was developed to measure the implant temperatures in vivo. A clinical study with 100 patients is planned to measure the implant temperatures for different combinations of head and cup materials during walking. This study will answer the question of whether patients with synovia with poor lubricating properties may be at risk for thermally induced bone necrosis and subsequent implant failure. The study will also deliver the different friction properties of various implant materials and prove the significance of wear simulator tests. A clinically successful titanium hip endoprosthesis was modified to house the electronics inside its hollow neck. The electronics are powered by an external induction coil fixed around the joint. A temperature sensor inside the implant triggers a timer circuit, which produces an inductive pulse train with temperature-dependent intervals. This signal is detected by a giant magnetoresistive sensor fixed near the external energy coil. The implant temperature is measured with an accuracy of 0.1°C in a range between 20°C and 58°C and at a sampling rate of 2–10 Hz. This rate could be considerably increased for measuring other data, such as implant strain or vibration. The employed technique of transmitting data from inside of a closed titanium implant by low frequency magnetic pulses eliminates the need to use an electrical feedthrough and an antenna outside of the implant. It enables the design of mechanically safe and simple instrumented implants.
Bergmann, Georg; Graichen, Friedmar; Dymke, Jorn; Rohlmann, Antonius; Duda, Georg N.; Damm, Philipp
To determine whether femoral implant position can be reproducibly measured on plain digital radiographs, we prospectively studied 40 patients after hip resurfacing arthroplasty. Three observers performed double blinded randomized analysis of calibrated digital radiographs meeting strict quality criteria. The implant stem-shaft angle and femoral anteversion angle were measured by the trapezoid method of axis determination using OsiriX software. The upper and lower offset and the anterior and posterior offset were measured. The statistical analysis was performed using Pearson correlation tests (intra-observer reproducibility) and Fisher F tests (inter-observer reproducibility). Intra-observer reproducibility was very good for all parameters and all observers. Inter-observer reproducibility was excellent except for superior offset measurement. Thus, this study validates a radiographic method for assessing the femoral implant position in hip resurfacing. We believe this could be useful for future studies on hip resurfacing devices. PMID:23558663
Pailhé, Régis; Reina, Nicolas; Ancelin, David; Cavaignac, Etienne; Maubisson, Laurent; Sharma, Akash; Chiron, Philippe
Low-carbon Stellite 21 has been used as hip implant material for a number of decades; however, its limited metal-on-metal bearing has resulted in loosening between the femoral head and the acetabular cup of hip implants. In order to improve the metal-on-metal bearing, it is proposed that a high-carbon alloy, Stellite 720, surface coating be applied on Stellite 21 hip implants to improve mechanical and tribological performance. For this coating to be practical, it must also meet the requirements of corrosion resistance for orthopedic implant materials. In this research, Stellite 720 is investigated with pin-on-disk wear tests, and electrochemical and immersion corrosion tests in simulated human body fluid (Hank's solution; pH 7.4 at temperature of 37°C). The experimental results demonstrate that Stellite 720 exhibits much better wear resistance than Stellite 21, and has the potential for better corrosion resistance as well. The applicability of coating Stellite 21 hip implants with Stellite 720 is discussed.
Hu, P. S.; Liu, R.; Liu, J.; McRae, G.
Implants used for hip and knee arthroplasties have recently come under increased scrutiny. In England, a large variety of prostheses are currently being used. With the need for savings within the NHS of up to £20 billion over the next five years, we should be 'getting it right first time' by using the most reliable implants with proven survivorship. The 8th Annual Report from the NJR (2011) reporting on prostheses used in 2010 was analysed to determine whether implants had published survivorship data. This study demonstrates that the majority of implants did have long-term results but a small percentage had no published data. The cost of these implants was calculated to see if the implants provided best value for money based on survivorship. Implant choice was also correlated to revision rates published in the NJR report (2011) to help determine whether their continued use was justified. PMID:23507062
Ng Man Sun, Stephen; Gillott, Elizabeth; Bhamra, Jagmeet; Briggs, Tim
We compared the 3 to 5 year clinical and radiological results of two different hybrid metal-on-metal resurfacing hip arthroplasty designs in 28 patients who had undergone bilateral hip resurfacing with ReCap implants on one side and BHR implants on the other side. Both hips were compared in each patient, to specifically evaluate the bone response to the cemented femoral component. Post operative function was measured with the Harris Hip Score and University of California at Los Angeles (UCLA) Activity Score, and was excellent in these patients. Mean cup inclination was 43.3 degrees +/- 7 degrees (43.3 degrees +/- 7 degrees for the BHR and 43.4 +/- 6 degrees for the Recap). The inclination angle was greater than 45 degrees in 15 patients: 7 with a BHR, 8 with a Recap; eight patients showed inclination angles greater than 50 degrees (4 patients in each group). All acetabular monoblock cups were well fixed. One patient (1.8%) had radiographs showing bone changes of uncertain significance around the stem of the femoral component. Three percent had femoral bone resorption in the BHR hip and two percent showed bone resorption in the ReCap hip. There was no evidence of migration of the femoral components. The dual energy X-ray absorptiometry (DEXA) scans identified no real reduction in bone density in these resurfacing hip arthroplasties. None of these hips showed any other adverse features. The biological response showed no difference for the two different designs of resurfacing hip arthroplasties. PMID:22187835
Delport, Hendrik P; De Schepper, Jo; Smith, Evert J; Nichols, Margaret; Bellemans, Johan
Static load testing of sliding screw-plate hip implants manufactured from Cobalt-Chromium-Molybdenum alloy or 316 LVM stainless steel was performed. Implant angles of 135 degrees and 150 degrees were applied and the telescoping ability eliminated by gluing the screw to the barrel of the implant. In comparison with the results obtained in tests of McLaughlin and Jewett hip implants superior yield loads were determined for both implant angles. Calculations were made of the improvement of implant strength due to telescoping. Implants with a 135 degree angle are recommended for the fixation of unstable trochanteric fractures, as the hip joint load during normal level walking does not exceed the yield load of these implants. PMID:7446052
Jensen, J S
Particulate wear debris from hip joint replacements is an important factor in determining the response of the surrounding tissue to the implants. Failed replacement joints are surrounded by a layer of fibrous tissue showing an inflammatory response to the wear debris. This reaction leads to bone resorption and the eventual failure of the prosthesis. In preliminary experiments the Oxford scanning
G. W. Grime; J. T. Triffitt; M. C. Williamson; N. A. Athanasou
While price capitation strategies may help to control total hip (THA) and knee arthroplasty (TKA) implant costs, its effect on premium implant selection is unclear. Primary THA and TKA cases 6months before and after capitated pricing implementation were retrospectively identified. After exclusions, 716 THA and 981 TKA from a large academic hospital and 2 midsize private practice community hospitals were reviewed. Academic hospital surgeons increased premium THA implant usage (66.5% to 70.6%; P=0.28), while community surgeons selected fewer premium implants (36.4%) compared to academic surgeons, with no practice change (P=0.95). Conversely, premium TKA implant usage significantly increased (73.4% to 89.4%; P<0.001) for academic surgeons. Community surgeons used premium TKA implants at greater rates in both periods, with all cases having ?1 premium criterion. PMID:24679475
Farías-Kovac, Mario; Szubski, Caleb R; Hebeish, Mark; Klika, Alison K; Mishra, Kirtishri; Barsoum, Wael K
This study was performed to determine whether patients who sustain an intertrochanteric fracture have better outcomes when stabilized using a sliding hip screw or an intramedullary nail. A 20% sample of Part A and B entitled Medicare beneficiaries 65 years or older was used to generate a cohort of patients who sustained intertrochanteric femur fractures between 1999 and 2001. Two fracture implant groups, intramedullary nail and sliding hip screw, were identified using Current Procedural Terminology and International Classification of Diseases, 9th Revision codes. The cohort consisted of 43,659 patients. Patients treated with an intramedullary nail had higher rates of revision surgery during the first year than those treated with a sliding hip screw (7.2% intramedullary nail versus 5.5% sliding hip screw). Mortality rates at 30 days (14.2% intramedullary nail versus 15.8% sliding hip screw) and 1 year (30.7% intramedullary nail versus 32.5% sliding hip screw) were similar. Adjusted secondary outcome measures showed significant increases in the intramedullary nail group relative to the sliding hip screw group for index hospital length of stay, days of rehabilitation services in the first 6 months after discharge, and total expenditures for doctor and hospital services. Level of Evidence: Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
Aros, Brian; Tosteson, Anna N. A.; Gottlieb, Daniel J.
We developed a finite element model to preclinically test cemented hip implants for damage accumulation, including cement crack formation, creep, and stem migration. Using this model, we simulated the mechanical failure processes of four cemented total hip arthroplasty implants (Lubinus SPII, Mueller Curved, Exeter and Charnley, all with known clinical results) during cyclic normal walking and stair-climbing loads. These four implants were selected to ascertain whether the simulation predicted greater damage development around clinically inferior stems, whether clinically inferior designs could be identified by an initial stress analysis without the prediction of cement damage, and whether the simulation could predict high implant subsidence rates in combination with minimal cement damage. Based on the predicted cement crack patterns and crack formation rates, the simulation correctly identified the clinically inferior implant designs. Based only on the initial stress analysis under a stair-climbing load, it was not possible to identify clinically inferior designs. High subsidence values and minimal cement damage were predicted for the Exeter implant, similar to clinical findings. Our findings suggest the simulation may be effective in differentiating between a range of implants and design features. PMID:17075379
Stolk, Jan; Janssen, Dennis; Huiskes, Rik; Verdonschot, Nico
In case of periprosthetic hip infections the implantation of antibiotic-loaded PMMA spacers is accepted for an adequate treatment option. Although their indication for the treatment of destructive, bacterial infections of the proximal femur would make sense, literature data are scarce. Hence, the aim of this study was to evaluate the efficacy of antibiotic-impregnated spacers in the treatment of proximal femur infections. In 10 consecutive patients (5 M/ 5 F, mean age 66 y.) with bacterial proximal femur infections, a femoral head/neck resection was prospectively performed with a subsequent implantation of an antibiotic-loaded spacer. The joint-specific outcome was evaluated by the Merle d´Aubigne and the Mayo hip score, the general outcome by SF-36. The time periods were divided into “infection situation”, “between stages” and meanly 1 year “after prosthesis implantation”. The spacers were meanly implanted over 90 [155-744] days. In all cases an infection eradication could be achieved. After infection eradication, a prosthesis implantation was performed in 8 cases. The general scores showed significant increases at each time period. With regard to the dimension “pain”, both scores demonstrated a significant increase between “infection situation” and “between stages”, but no significance between “between stages” and “after prosthesis implantation”. Spacers could be indicated in the treatment of proximal femur infections. Besides an infection eradication, a pain reduction is also possible.
Kelm, J.; Bohrer, P.; Schmitt, E.; Anagnostakos, K.
Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr
Alister J. Hart; Ann Sandison; Paul Quinn; Barry Sampson; Kirk D. Atkinson; John A. Skinner; Angela Goode; Jonathan J. Powell; J. Frederick W. Mosselmans
A retrospective clinical and radiographic analysis was performed on 58 patients (60 hips; mean age at time of surgery, 45.2 years) at a minimum of 10-year follow-up (mean, 12.7 years) after total hip replacement using a ceramic-on-ceramic bearing total hip implant (Autophor, Smith and Nephew, Memphis, TN). Mean wear rate at final follow-up was 0.21 mm, averaging 0.016 mm\\/y. There
Laith M. Jazrawi; Eric Bogner; Craig J. Della Valle; Frank S. Chen; Kevin I. Pak; Steven A. Stuchin; Victor H. Frankel; Paul E. Di Cesare
Knee rotationplasty was initially proposed for the reconstruction of the knee joint in the congenital hypoplasia of the femur. Its application was extended to functional reconstruction of the knee joint after wide resection of malignant bone or soft tissue tumor around the knee. It has also been shown to salvage a failed knee-sparing surgery due to infection or the aseptic loosening of the prosthesis. Hip rotationplasty has been described as a method for the reconstuction of hip function, as well as in the knee joint, in the case of a primary malignant tumor of the proximal part of the femur in children. It has also been described as having a surgical application for the severe congenital deficiency of the proximal part of the femur to reconstruct hip and knee joints, as well as for the massive bone defect of the proximal part of the femur due to infection to mimic a functional femoral shaft. This article reports a case where the hip joint was secondarily reconstructed with hip rotationplasty after subtotal resection of the femur due to infection of the hip hemiarthroplastic prosthesis and osteomyelitis of the hip joint and femur. PMID:19292368
Okazaki, Narihiro; Kumagai, Kenji; Egashira, Masayuki; Osaki, Makoto; Murata, Masakazu; Tomita, Masato; Shindo, Hiroyuki
With 332,000 operations carried out every year, the implantation of an artificial hip joint is one of the most common surgical operations performed in the US. According to prognosis which takes the demographical change into account, the number of these operations will increase in the coming years. One of the essential requirements is the perfect reconstruction of the biomechanical functions, especially the knowledge about the center of the hip rotation and the length of the leg. Based on this information it is possible to ensure the right position of the newly set leg during surgery. The aim of this work is to present and evaluate an optical measurement method in order to gather information about the center of the hip joint and the leg length. An appropriate laboratory setup has been designed and implemented in order to evaluate two different approaches: a structured light-method consisting of a DLP-Beamer or a laser source which projects defined patterns onto the patient and a marker-based system. Together with this both methods are combined with custom software to determine the hip joint center and the leg length with an accuracy of around +/- 0.2 inches. The clinical use of the tested approaches would give the surgeon the opportunity to reset the implant-parameters in the course of the surgery. In this way subsequent illnesses such as scoliotic pelvis can be prevented.
Maschke, R.; Lempe, B.; Taudt, Ch.; Rudek, F.; Baselt, T.; Basan, F.; Grunert, R.; Hartmann, P.
Most surgeons believe that some level of modularity has a valuable role to play in primary total hip arthroplasty. However, all modular junctions carry some risk and recent problems with taper tribocorrosion have elevated concerns. These problems suggest that more rigorous preclinical testing should be undertaken before new types of modularity are widely used. Efforts to further optimize these junctions where they are needed, avoidance of gratuitous use of modular junctions where they provide only modest benefits, and a judicious approach to adopting new modularity are reasonable approaches to current concerns. PMID:24655609
Berry, Daniel J
Background Several studies suggest that histologic findings from tissues obtained at revision arthroplasty for failed metal-on-metal\\u000a (MOM) total hip implants may reflect an immune reaction to particles or ions in some patients. However, only a limited number\\u000a of cases without MOM implants were reported as controls in those studies.\\u000a \\u000a \\u000a \\u000a \\u000a Questions\\/purposes The purpose of this study is to better define the extent and
Takaaki Fujishiro; Dirk Jan F. Moojen; Naomi Kobayashi; Wouter J. A. Dhert; Thomas W. Bauer
Due to higher friction artificial hip joints warm up more than natural joints during walking and other continuous activities. This could lead to thermal damage in the surrounding tissues and be a reason for long-term implant loosening, an effect which has not yet been investigated. In vivo measurements with instrumented implants showed temperatures inside the prosthetic head up to 43.1 degrees C (Part 1 of this work). Based on the experimental data a finite element model was developed to calculate the temperatures in the tissues surrounding the hip implant to determine whether these tissues can heat up to critical levels. Various parameters were investigated which could account for the variations in the measured temperatures in the patients, including the perfusion rate in tissues, the volume of synovial fluid, and different implant materials. We found that the synovial fluid is most endangered by thermal damage and consequent deterioration of lubricating properties. Implants with a cobalt-chromium head and a polyethylene cup are unfavourable as they can elevate the temperature in the synovia to more than 46 degrees C. With regard to thermal properties stems made from cobalt-chromium alloys are superior to titanium stems, by better conducting heat to the femur and minimizing the synovial fluid temperature. Factors determining the temperatures during walking are insufficiently known or cannot be determined in the individual patient. Therefore, the risk of a thermally induced implant loosening cannot currently be estimated. Under unfavourable conditions such a risk exists, however. General improvements of implant materials and clinical studies on the possibility of implant loosening due to high temperatures are therefore required. PMID:11266665
Bergmann, G; Graichen, F; Rohlmann, A; Verdonschot, N; van Lenthe, G H
Bilateral hip arthroplasty has been reported to be a safe and effective way to treat bilateral hip arthritis in a selective group of patients. We report a follow-up of 30 patients who underwent simultaneous bilateral total hip arthroplasty with hydroxyapatite implants and were followed for an average of 19.4 years. Patients had an average Harris Hip Score of 90 at the latest follow-up (range, 78-99). The average Western Ontario and McMaster Universities Arthritis Index questionnaire index score was 12 (range, 0-41), with high functional results on the 12-Item Short Form Health Survey (SF-12) and Oxford 12 questioners. Using the Kaplan-Meier survivorship analysis, with revision for any reason as an end point, survivorship was 94% at 12 years, 88% at 15 years, 74% at 18 years, and 61% at 23 years. All revisions were for the acetabular component, and the survivorship for the femoral component was 100% throughout the 23-year period. We conclude that bilateral uncemented total hip arthroplasty can provide satisfactory long-term clinical, radiological, and functional outcomes in patients even with older-generation polyethylene liners and stem designs. PMID:22177794
Schwarzkopf, Ran; Olivieri, Patrick; Jaffe, William L
Background and purpose Cementless total hip arthroplasty is currently favored by many orthopedic surgeons. The design of the porous surface is critically important for long-term fixation. We examined the clinical and radiographic outcome of the cementless titanium hip implant with a bottom coating of apatite-wollastonite containing bioactive glass ceramic. Methods We retrospectively reviewed 109 hips (92 patients) that had undergone primary cementless total hip arthroplasty with bioactive glass ceramic bottom-coated implants. The mean follow-up period was 7 (3–9) years. Hip joint function was evaluated with the Merle d’Aubigné and Postel hip score, and radiographic changes were determined from anteroposterior radiographs. Results The mean hip score improved from 9.7 preoperatively to 17 at the final follow-up. The overall survival rate was 100% at 9 years, when radiographic loosening or revision for any reason was used as the endpoint. 3 stems in 2 patients subsided more than 3 mm vertically within 1 year after implantation. Radiographs of the interface of the stem and femur were all classified as bone ingrowth fixation. Conclusions The short-term results of this study show good outcome for cementless implants with a bottom coating of apatite-wollastonite containing bioactive glass ceramic.
Septic loosening of total hip and knee endoprostheses gains an increasing proportion of revision arthroplasties. Operative revisions of infected endoprostheses are mentally and physically wearing for the patient, challenging for the surgeon and a significant economic burden for healthcare systems. In cases of early infection within the first three weeks after implantation a one-stage revision with leaving the implant in place is widely accepted. The recommendations for the management of late infections vary by far. One-stage revisions as well as two-stage or multiple revision schedules have been reported to be successful in over 90% of all cases for certain patient collectives. But implant associated infection still remains a severe complication. Moreover, the management of late endoprosthetic infection requires specific logistics, sufficient and standardized treatment protocol, qualified manpower as well as an efficient quality management. With regard to the literature and experience of specialized orthopaedic surgeons from several university and regional hospitals we modified a commonly used treatment protocol for two-stage revision of infected total hip and knee endoprostheses. In addition to the achievement of maximum survival rate of the revision implants an optimisation of the functional outcome of the affected artificial joint is aimed for.
Ellenrieder, Martin; Lenz, Robert; Haenle, Maximilian; Bader, Rainer; Mittelmeier, Wolfram
Hip implant retrieval analysis is the most important source of insight into the performance of new materials and designs of hip arthroplasties. Even the most rigorous in vitro testing will not accurately simulate the behavior of implant materials and new designs of prosthetic arthroplasties. Retrieval analysis has revealed such factors as the effects of gamma-in-air sterilisation of polyethylene, fatigue failure mechanisms of polymethylmethacrylate bone cement, fretting corrosion of Morse taper junctions, third body wear effects of both hard-on-hard and hard-on-soft bearing couples, and the effects of impingement of components on the full spectrum of bearing surfaces, none of which was predicted by pre-implantation in vitro testing of these materials and combinations. The temporal sequence of the retrieval process is approximately six years from first implantation through retrieval analysis, laboratory investigation, and publication of results, and thus, in addition to rigorous clinical evaluation, represents the true development and insight cycle for new designs and materials. PMID:23118372
Cuckler, J M
Stress dependent electrochemical dissolution is identified as one of the key mechanisms governing surface degradation in fretting and crevice corrosion of biomedical implants. The present study focuses on delineating the roles of mechanical stress and chemical conditions on the life expectancy of modular hip implants. First, material removal on a stressed surface of Ti6Al4V subjected to single asperity contact is investigated experimentally to identify the influence of contact load, in-plane stress and chemical environment on mean wear rates. A range of known stress levels are applied to the specimen while its surface is mechanically stimulated in different non-reactive to oxidizing aqueous environments. Evolution of surface degradation is monitored, and its mechanism is elucidated. This phase allows estimation of Preston Constant which is later used in the analysis. Second phase of the work is semi-analytical and computational, where, based on the estimated Preston constant and other material and process parameters, the scratch propensity (consisting of magnitude of scratch depth and their frequency per unit area) due to micro-motion in modular hip implants is estimated. The third phase views these scratches as initial notches and utilizes a mixed-mode fatigue crack propagation model to estimate the critical crack length for onset of instability. The number of loading cycles needed to reach this critical crack length is then labeled as the expected life of the implant under given mechanical and chemical conditions. Implications of different material and process conditions to life expectancy of orthopedic implants are discussed. It is observed that transverse micro-motion, compared to longitudinal micro-motion, plays a far more critical role in determining the implant life. Patient body weight, as well as proximity of the joint fluid to its iso-electric point play key roles in determining wear rates and associated life expectancies of modular hip implants. Sustained aeration of joint fluid, as well as proper tolerancing of mating surfaces, along with a proper choice of material microstructure may be utilized to extend implant life. PMID:22098898
Chandra, A; Ryu, J J; Karra, P; Shrotriya, P; Tvergaard, V; Gaisser, M; Weik, T
Modification of the nail-plate junction of conventional McLaughlin implants were manufactured. An additional washer was introduced between the back of the nail and the plate extension or the contract area was extended by modifying the nail base. Mechanical testing of the strength of the two modifications was performed. It is concluded that these modifications combined with replacement of the stiff nail by a sliding nail might provide a free angle device suitable for fracture fixation in trochanteric fractures. PMID:7331790
Jensen, J S
Background The aim of the study was to examine the reactivity of peripheral human leukocytes to various metal ions prior and following hip replacement in order to investigate implant-induced metal sensitivity. Methods Three patient groups were set up: (1) individuals without implants and no history of metal allergy (7 cases), (2) individuals without implants and known history of metal allergy (7 cases), and (3) patients undergoing cementless hip replacement (40 cases). Blood samples were taken in groups 1 and 2 at three different occasions; in group 3, prior and 3, 6, 12, 24, and 36 months after surgery. Peripheral leukocytes were separated and left either untreated or challenged with Ti, NiCl2, CoCl2, CrCl3, and phytohemagglutinin. Cell proliferation, cytokine release, and leukocyte migration inhibition assays were performed. Metal-induced reactivity was considered when all three assays showed significant change. Skin patch tests were also carried out. Results Both skin patch tests and leukocyte functional tests were negative in group 1, and both were positive in group 2. In group 3, after 6 months, 12% of the patients showed reactivity to the tested metals except for NiCl2. Following the 36-month period, 18% of group three became sensitive to metals (including all the earlier 12%). In contrast, patch tests were negative at each time point in group 3. Conclusions Orthopedic implant material may induce metal reactivity after implantation in a manner where susceptibility is yet to be elucidated. Leukocyte triple assay technique might be a useful tool to test implant material-related sensitivity.
In a previous work a finite elements model was constructed to simulate a fatigue assay according to the norm IRAM 9422-3. Three materials were studied, two of them are the most used in this type of implant (Stainless steel 3161 and alloy T16A14V) and the third was a new developed titanium alloy (Ti35Nb7Zr5Ta). Static loads were applied to the model according to the highest requirements of the norm and the stress - strain distribution were determined. In this study a simplified analysis of the material's fatigue was done according to the previous work. The best behavior of the titanium alloys vs. the stainless steel was evident. With the objective of studying the behavior of both: the implant and the femur bone, new finite elements models were realized, in which the presence of the bone was considered. Inside the bone, the femoral component of the implant was placed in a similar way of a cemented prosthesis in a total hip arthroplasty. The advantage of the titanium implant related to the stainless steel one, was very clear.
Oldani, C. R.; Dominguez, A. A.
Metal staining of alumina ceramic femoral heads can occur during implantation of total hip components and during reduction\\u000a of a dislocated total hip. To determine whether or not such staining results in surface damage to alumina ceramic femoral\\u000a heads in vivo, we examined two groups of explanted femoral heads. Group 1 consisted of four femoral heads with surface metal\\u000a staining
B. S. Bal; M. N. Rahaman; T. Aleto; F. S. Miller; F. Traina; A. Toni
Introduction Intervertebral spacers for anterior spine fusion are made of different materials, such as titanium and cobalt chromium alloys\\u000a and carbon fiber-reinforced polymers. Implant-related susceptibility artifacts can decrease the quality of MRI scans. The\\u000a aim of this cadaveric study was to demonstrate the extent that implant-related MRI artifacting affects the postfusion differentiation\\u000a of determined regions of interest (ROIs).\\u000a \\u000a \\u000a \\u000a Methods In six cadaveric
Thorsten Ernstberger; Gabert Heidrich; Wolfgang Schultz; Eckhardt Grabbe
We study soft tissues surrounding hip prostheses from three different patients. We evaluate the elemental composition of different fragments. The tissues are examined by means of two complementary methods in such analysis: Particle Induced X-ray Emission (PIXE) and Scanning Transmission Electron Microscopy (STEM) coupled with X-ray microanalysis (Energy Dispersive X-ray, EDX). These methods allow to determine locally at `macro' and `micro' level the chemistry of soft tissues. The findings confirmed the presence of metal in soft tissue near the three different hips. The tissues' composition undergoes important modifications with a systematic elevation of trace metal in patients with failed implants. We observe a corrosion which causes the continual release of particles into the tissues. Corrosion alters the shape size and chemical composition of wear particles embedded in soft tissue around the failed hip. EDX analysis showed that the wear particles contained varying quantities of titanium and aluminium. This phenomenon may be related with the variation of time of contact with soft tissues for each particle and Ti solubility.
Jallot, E.; Benhayoune, H.; Kilian, L.; Balossier, G.; Bonhomme, P.; Oudadesse, H.; Irigaray, J. L.
Background and purpose Glenoid reconstruction and inverted glenoid re-implantation is strongly advocated in revisions of failed reverse shoulder arthroplasty (RSA). Nevertheless, severe glenoid deficiency may preclude glenoid reconstruction and may dictate less favorable solutions, such as conversion to hemiarthropasty or resection arthropasty. The CAD/CAM shoulder (Stanmore Implants, Elstree, UK), a hip arthroplasty-inspired implant, may facilitate glenoid component fixation in these challenging revisions where glenoid reconstruction is not feasible. We questioned (1) whether revision arthroplasty with the CAD/CAM shoulder would alleviate pain and improve shoulder function in patients with failed RSA, not amenable to glenoid reconstruction, (2) whether the CAD/CAM hip-inspired glenoid shell would enable secure and durable glenoid component fixation in these challenging revisions. Patients and methods 11 patients with failed RSAs and unreconstructable glenoids underwent revision with the CAD/CAM shoulder and were followed-up for mean 35 (28–42) months. Clinical outcomes included the Oxford shoulder score, subjective shoulder value, pain rating, physical examination, and shoulder radiographs. Results The average Oxford shoulder score and subjective shoulder value improved statistically significantly after the revision from 50 to 33 points and from 17% to 48% respectively. Pain rating at rest and during activity improved significantly from 5.3 to 2.3 and from 8.1 to 3.8 respectively. Active forward flexion increased from 25 to 54 degrees and external rotation increased from 9 to 21 degrees. 4 patients required reoperation for postoperative complications. No cases of glenoid loosening occurred. Interpretation The CAD/CAM shoulder offers an alternative solution for the treatment of failed RSA that is not amenable to glenoid reconstruction.
Unexplained tissue inflammation in metal-on-metal hip replacements is suspected to be caused by implant-derived nanoparticles. The aim of this study was to investigate the nature of the metal particles in tissue surrounding metal-on-metal (MOM) hips that has been extracted during revision. Mapping of tissue surrounding the failed MOM hips was performed using microfocus X-ray Fluorescence (XRF). This revealed mainly Cr which was localized to the cellular regions. There was co-localisation of Co, were present, to areas of high Cr abundance. XANES of the tissue and appropriate standards revealed that the most common species were Cr(III) and Co(II). EXAFS analysis of the tissue and various metal standards revealed that the most abundant implant-related species was Cr(III) phosphate. Different tissue preparation methods, including frozen sectioning, were examined but were found not to affect the distribution or speciation of the metals in the tissue.
Hart, Alister J.; Sandison, Ann; Quinn, Paul; Sampson, Barry; Atkinson, Kirk D.; Skinner, John A.; Goode, Angela; Powell, Jonathan J.; Mosselmans, J. Frederick W.
The subsurface fatigue that occurs in the Ultra-High Molecular Weight Polyethylene (UHMWPE) hip joint cup has been shown to be correlated with the contact stress at that cup. This cup stress is known to be affected by the implant design, dimensions and materials. In this study, 3D finite element modeling has been used to investigate the effects on the cup
H. Fouad; S. M. Darwish
BACKGROUND: Modular neck adapters for hip arthroplasty stems allow the surgeon to modify CCD angle, offset and femoral anteversion intraoperatively. Fretting or crevice corrosion may lead to failure of such a modular device due to high loads or surface contamination inside the modular coupling. Unfortunately we have experienced such a failure of implants and now report our clinical experience with
Thomas M Grupp; Thomas Weik; Wilhelm Bloemer; Hanns-Peter Knaebel
Wear particle-induced inflammation leading to periprosthetic osteolysis remains a major cause of hip implant failure. As polyethylene particles from conventional metal-on-polyethylene implants have been associated with these failures, an interest in lower wear metal-on-metal (MM) bearings has emerged. However, the biological effects of nanometer-size chromium oxide particles, predominant type of wear particles produced by MM implants, remain mostly unknown. Therefore, this study aimed to determine the cytotoxicity of nanometer-size Cr2O3 particles on macrophages in vitro, by analyzing their effects on cell mortality and cytokine release and comparing them with those of similarly-sized alumina (Al2O3) particles (known to be relatively bioinert). Results showed that at high concentrations, nanometer-size Cr2O3 particles can be cytotoxic to macrophages, inducing significant decreases in total cell numbers and increases in necrosis. Results also showed that, at high concentrations, the cytotoxicity of Cr 2O3 particles was overall higher than that of Al2O 3 particles, even though Cr2O3 and Al2O 3 are both stable forms of ceramic materials. However, it appeared to be lower than that of previously reported conventional polyethylene and CoCrMo particles. Therefore, chromium oxide particles may not be the main culprit in initiating the inflammatory reaction in MM periprosthetic tissues.
Many concepts have been devised for the treatment of late periprosthetic infections of total hip prostheses. A two-stage revision with a temporary antibiotic-impregnated cement spacer and a cemented prosthesis appears to be the most preferred procedure although, in recent times, there seems to be a trend towards cementless implants and a shorter period of anti- biotic treatment. Because of the
In the current era of total hip arthroplasty (THA), orthopedic surgeons have several fixation options at their disposal. The modern monoblock prosthesis, introduced by Dr. Sir John Charnley, has seen many modifications since its inception in the 1970s and continues to be the most commonly used prosthesis style for primary and revision THA. Proximal modular sleeve technology was introduced in 1967 by Konstantin Sivash, modifying his original 1956 Sivash Stem design. The design is now known as the S-ROM, and although design modifications continue to date, the fundamental structure of the S-ROM remains essentially unchanged. Several other proximal modular prostheses are now currently available for use in THA. Although this similarity in design enables considerable surgical flexibility, it also links their potential for catastrophic failure. This aim of this article was to present a brief history of proximal modularity in THA and to add to the small body of literature regarding catastrophic failure in modular hip implants, including its proposed etiologies including micromotion, fretting and corrosion. PMID:23823060
Mehran, Nima; North, Trevor; Laker, Michael
With the resurgence of composite materials in orthopaedic applications, a rigorous assessment of stress is needed to predict any failure of bone-implant systems. For current biomechanics research, strain gage measurements are employed to experimentally validate finite element models, which then characterize stress in the bone and implant. Our preliminary study experimentally validates a relatively new nondestructive testing technique for orthopaedic implants. Lock-in infrared (IR) thermography validated with strain gage measurements was used to investigate the stress and strain patterns in a novel composite hip implant made of carbon fiber reinforced polyamide 12 (CF/PA12). The hip implant was instrumented with strain gages and mechanically tested using average axial cyclic forces of 840 N, 1500 N, and 2100 N with the implant at an adduction angle of 15 deg to simulate the single-legged stance phase of walking gait. Three-dimensional surface stress maps were also obtained using an IR thermography camera. Results showed almost perfect agreement of IR thermography versus strain gage data with a Pearson correlation of R(2) = 0.96 and a slope = 1.01 for the line of best fit. IR thermography detected hip implant peak stresses on the inferior-medial side just distal to the neck region of 31.14 MPa (at 840 N), 72.16 MPa (at 1500 N), and 119.86 MPa (at 2100 N). There was strong correlation between IR thermography-measured stresses and force application level at key locations on the implant along the medial (R(2) = 0.99) and lateral (R(2) = 0.83 to 0.99) surface, as well as at the peak stress point (R(2) = 0.81 to 0.97). This is the first study to experimentally validate and demonstrate the use of lock-in IR thermography to obtain three-dimensional stress fields of an orthopaedic device manufactured from a composite material. PMID:21823752
Bougherara, Habiba; Rahim, Ehsan; Shah, Suraj; Dubov, Anton; Schemitsch, Emil H; Zdero, Rad
Introduction Suitable treatment of early failure of total hip replacement is critical in younger patients, as bone stock is lost and the functional outcome is impaired. Case presentation We report the case of a 56-year-old Caucasian woman with early failure of hip resurfacing arthroplasty. While revision is usually performed with a conventional hip implant, this case report describes for the first time a revision procedure with a bone-conserving short-stem hip implant. Conclusions Our approach allows further conservation of femoral bone stock and provides a long-term solution to the patient, which maintains the possibility of using a conventional hip implant should a second revision become necessary.
Metal-on-metal hip arthroplasties undergo distinct release of toxic metal particles and ions. Thus, it is necessary to minimize this. In order to evaluate the wear behaviour of metal-on-metal hip replacements it is essential to understand the micro-structural changes in the sub-surface region. Previous studies revealed that cobalt chromium metal-on-metal implants are able to alter their mechanical behaviour by adjusting the microstructure to load. The reason for this is the so-called mechanical mixing. This means that a nano-crystal layer is formed by rotating clusters of atoms that incorporate denatured proteins from the interfacial medium. This is followed by a layer of rhombic shaped nano-crystals in between sheared epsilon-martensite lathes, twins, and stacking faults. Although the primary wear zone has been well characterized, the sub-surface structure of the stripe wear and the non-contact zone of the hip ball have yet to be analysed. For this study a 28-mm cobalt base alloy femoral head and acetabular cup were analysed. The implant was simulator tested for 5 million cycles with the application of micro-separation resulting in a clearly visible stripe wear appearance. The TEM micrograph of the primary wear zone of the ball confirmed the presence of a sub-surface layer of nano-crystals. The thickness of this layer was approximately 200 nm and the average grain diameter ranged from 35 to 40 nm. Within the stripe wear zone the micrographs also revealed a nano-crystal layer but with a thickness of only 50 nm and an average grain diameter from 15 to 20 nm. The carbon and oxygen content was highest closest to the surface which proves the occurrence of mechanical mixing. The non-contact zone of the ball was analysed as well. When compared to the primary wear zone a nano-crystal layer with similar thickness but with an average grain diameter smaller than 15 nm was observed. PMID:19627822
Pourzal, Robin; Theissmann, Ralf; Williams, Sophie; Gleising, Birgit; Fisher, John; Fischer, Alfons
The effect of geometry change of the bearing surfaces owing to wear on the elastohydrodynamic lubrication (EHL) of metal-on-metal (MOM) hip bearings has been investigated theoretically in the present study. A particular MOM Metasul bearing (Zimmer GmbH) was considered, and was tested in a hip simulator using diluted bovine serum. The geometry of the worn bearing surface was measured using a coordinate measuring machine (CMM) and was modelled theoretically on the assumption of spherical geometries determined from the maximum linear wear depth and the angle of the worn region. Both the CMM measurement and the theoretical calculation were directly incorporated into the elastohydrodynamic lubrication analysis. It was found that the geometry of the original machined bearing surfaces, particularly of the femoral head with its out-of-roundness, could lead to a large reduction in the predicted lubricant film thickness and an increase in pressure. However, these non-spherical deviations can be expected to be smoothed out quickly during the initial running-in period. For a given worn bearing surface, the predicted lubricant film thickness and pressure distribution, based on CMM measurement, were found to be in good overall agreement with those obtained with the theoretical model based on the maximum linear wear depth and the angle of the worn region. The gradual increase in linear wear during the running-in period resulted in an improvement in the conformity and consequently an increase in the predicted lubricant film thickness and a decrease in the pressure. For the Metasul bearing tested in an AMTI hip simulator, a maximum total linear wear depth of approximately 13 microm was measured after 1 million cycles and remained unchanged up to 5 million cycles. This resulted in a threefold increase in the predicted average lubricant film thickness. Consequently, it was possible for the Metasul bearing to achieve a fluid film lubrication regime during this period, and this was consistent with the minimal wear observed between 1 and 5 million cycles. However, under adverse in vivo conditions associated with start-up and stopping and depleted lubrication, wear of the bearing surfaces can still occur. An increase in the wear depth beyond a certain limit was shown to lead to the constriction of the lubricant film around the edge of the contact conjunction and consequently to a decrease in the lubricant film thickness. Continuous cycles of a running-in wear period followed by a steady state wear period may be inevitable in MOM hip implants. This highlights the importance of minimizing the wear in these devices during the initial running-in period, particularly from design and manufacturing points of view. PMID:16225148
Liu, F; Jin, Z M; Hirt, F; Rieker, C; Roberts, P; Grigoris, P
Background Modern metal-on-metal hip resurfacing implants are being increasingly used for young and active patients, although the long-term outcome and failure mechanisms of these implants are still unknown. In this consecutive revision case series, early failures of femoral implants (at < 4 years) were studied. Methods 3 revisions were done due to a fracture of the femoral neck and 1 due to loosening and varus position of the femoral component. Femoral heads were removed en bloc 2–46 months after the primary operation, embedded in methylmethacrylate, sectioned, stained, and analyzed as whole-mount specimens in 4 55–62-year-old patients with osteoarthritis. Results Histopathology was characterized by new but also partly healed trabecular microfractures, bone demineralization, cysts, metallosis, and abnormal formation of new woven bone. All samples displayed signs of notching, osteoporosis, and aseptic necrosis, which seemed to have been the main reason for the subsequent development and symptoms of the patients and revision operations of the hips. Interpretation Based on these early revision cases, it appears that aseptic necrosis is a common cause of early loosening of resurfacing hip implants.
Stogiannidis, Ioannis; Puolakka, Timo; Pajamaki, Jorma; Moilanen, Teemu
BackgroundThe Dynamic Hip Screw is well established for the treatment of femoral neck fractures. However, cut-out occurs in 1–6% of all cases. This study compared the biomechanical performance of a helical shaped implant (DHS-Blade) to the Dynamic Hip Screw in an unstable femoral neck fracture model.
Markus Windolf; Volker Braunstein; Christof Dutoit; Karsten Schwieger
Background The few available studies directly comparing aseptic and septic joint revision surgery report conflicting results. We investigated whether two-stage revision of septic hip prosthesis with a preformed antibiotic-loaded spacer and an uncemented prosthesis provides hip function and quality of life similar to those provided by aseptic revision surgery in the medium term, as well as the associated direct hospital costs. Materials and methods We prospectively evaluated the hip function (Harris hip score) and quality of life (WOMAC and SF-12 scores) of 80 patients who underwent one-stage revision for aseptic loosening (Group A, 40 patients) or two-stage revision for septic total hip prostheses (Group S, 40 patients). Patients were matched for gender, age, and bone loss. A preformed antibiotic-loaded cement spacer was used for two-stage revision, and uncemented modular prostheses were implanted at revision in both groups. The minimum follow-up was 2 years (average 4 years; range 2–6 years). Results We found no difference in infection recurrence or aseptic loosening rate in the two groups. Average Harris hip score increased similarly in both groups: from 19.1 to 74.0 in Group A versus 15.0–71.2 in Group S. Patient-reported quality-of-life questionnaires (SF-12 and WOMAC) at last follow-up were similar postoperatively, but the complication rate for Group S was twice that of Group A (20.8 versus 10%). Mean overall hospital-related costs of two-stage procedures were 2.2 times greater than those for aseptic revisions. Conclusions Two-stage revision for infected hip prostheses, using a preformed antibiotic-loaded cement spacer and uncemented revision prosthesis, offers a success rate comparable to noninfected revisions in the medium term but is associated with a higher complication rate and costs.
Romano, Delia; Logoluso, Nicola; Meani, Enzo
Diameter and diametral clearance of the bearing surfaces of metal-on-metal hip implants and structural supports have been recognised as key factors to reduce the dry contact and hydrodynamic pressures and improve lubrication performance. On the other hand, application of aspherical bearing surfaces can also significantly affect the contact mechanics and lubrication performance by changing the radius of the curvature of a bearing surface and consequently improving the conformity between the head and the cup. In this study, a novel metal-on-metal hip implant employing a specific aspherical bearing surface, Alpharabola, as the acetabular surface was investigated for both contact mechanics and elastohydrodynamic lubrication under steady-state conditions. When compared with conventional spherical bearing surfaces, a more uniform pressure distribution and a thicker lubricant film thickness within the loaded conjunction were predicted for this novel Alpharabola hip implant. The effects of the geometric parameters of this novel acetabular surface on the pressure distribution and lubricant thickness were investigated. A significant increase in the predicted lubricant film thickness and a significant decrease in the dry contact and hydrodynamic pressures were found with appropriate combinations of these geometric parameters, compared with the spherical bearing surface. PMID:20003978
Meng, Qingen; Gao, Leiming; Liu, Feng; Yang, Peiran; Fisher, John; Jin, Zhongmin
The initial fixation of a cemented hip implant relies on the strength of the interface between the stem, bone cement and adjacent bone. Bone cement is used as grouting material to fix the prosthesis to the bone. The curing process of bone cement is an exothermic reaction where bone cement undergoes volumetric changes that will generate transient stresses resulting in residual stresses once polymerization is completed. However, the precise magnitude of these stresses is still not well documented in the literature. The objective of this study is to develop an experiment for the direct measurement of the transient and residual radial stresses at the stem-cement interface generated during cement polymerization. The idealized femoral-cemented implant consists of a stem placed inside a hollow cylindrical bone filled with bone cement. A sub-miniature load cell is inserted inside the stem to make a direct measurement of the radial compressive forces at the stem-cement interface, which are then converted to radial stresses. A thermocouple measures the temperature evolution during the polymerization process. The results show the evolution of stress generation corresponding to volumetric changes in the cement. The effect of initial temperature of the stem and bone as well as the cement-bone interface condition (adhesion or no adhesion) on residual radial stresses is investigated. A maximum peak temperature of 70 degrees C corresponds to a peak in transient stress during cement curing. Maximum radial residual stresses of 0.6 MPa in compression are measured for the preheated stem. PMID:18692188
Nuño, N; Madrala, A; Plamondon, D
Metal on metal resurfacing hip implants are known to have complications unique to this type of implant. The case presented adds a further previously not described complication, the dislocation and spontaneous reduction of the pin of the femoral component against the femoral neck. The radiographic and CT findings are demonstrated. The dislocation was aided by bone loss due to an
Metal on metal resurfacing hip implants are known to have complications unique to this type of implant. The case presented adds a further previously not described complication, the dislocation and spontaneous reduction of the pin of the femoral component against the femoral neck. The radiographic and CT findings are demonstrated. The dislocation was aided by bone loss due to an
The surfaces of retrieved failed cementless total hip implants made of cobalt-chromium-molybdenum casting alloy and of wrought titanium 6-aluminum 4-vanadium alloy were studied with the use of scanning-electron microscopy (SEM), energy-dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). New implants of the same make served as controls. The XPS scans revealed a dense carbon layer on the entire analyzed specimen. The relative composition of the titanium alloy implants showed an overall agreement with the international standards for implants for surgery, and the overall surface composition did not change over the period of the implantation. However, an inhomogeneous distribution of the constituents could be demonstrated in the retrieved as well as in the new MEC-screw rings made of TiAl6V4 alloy, an implant that has been linked to a high early failure rate. In the CoCr-alloy components (Lord-screw rings) a high percentage of aluminum, mainly organized in aluminum inclusions, was found in the retrieved as well as in the new implants. PMID:12516084
Decking, R; Reuter, P; Hüttner, M; Puhl, W; Claes, L E; Scharf, H P
Titanium alloys are widely used in total-joint replacements due to a combination of outstanding mechanical properties, biocompatibility, passivity, and corrosion resistance. Nevertheless, retrieval studies have pointed out that these materials can be subjected to localized or general corrosion in modular interfaces when mechanical abrasion of the oxide film (fretting) occurs. Modularity adds large crevice environments, which are subject to micromotion between contacting interfaces and differential aeration of the surface. Titanium alloys are also known to be susceptible to hydrogen absorption, which can induce precipitation of hydrides and subsequent brittle failure. In this work, the surface of three designs of retrieved hip-implants with Ti-6Al-4V/Ti-6Al-4V modular taper interfaces in the stem were investigated for evidence of severe corrosion and precipitation of brittle hydrides during fretting-crevice corrosion in the modular connections. The devices were retrieved from patients and studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and chemical analysis. The surface qualitative investigation revealed severe corrosion attack in the mating interfaces with evidence of etching, pitting, delamination, and surface cracking. In vivo hydrogen embrittlement was shown to be a mechanism of degradation in modular connections resulting from electrochemical reactions induced in the crevice environment of the tapers during fretting-crevice corrosion. PMID:18683224
Rodrigues, Danieli C; Urban, Robert M; Jacobs, Joshua J; Gilbert, Jeremy L
Titanium alloys are widely used in total-joint replacements due to a combination of outstanding mechanical properties, biocompatibility, passivity and corrosion resistance. Nevertheless, retrieval studies have pointed out that these materials can be subjected to localized or general corrosion in modular interfaces when mechanical abrasion of the oxide film (fretting) occurs. Modularity adds large crevice environments, which are subject to micromotion between contacting interfaces and differential aeration of the surface. Titanium alloys are also known to be susceptible to hydrogen absorption, which can induce precipitation of hydrides and subsequent brittle failure. In this work, the surface of three designs of retrieved hip-implants with Ti-6Al-4V/Ti-6Al-4V modular taper interfaces in the stem were investigated for evidence of severe corrosion and precipitation of brittle hydrides during fretting-crevice corrosion in the modular connections. The devices were retrieved from patients and studied by means of scanning electron microscopy (SEM), x-ray diffraction (XRD) and chemical analysis. The surface qualitative investigation revealed severe corrosion attack in the mating interfaces with evidence of etching, pitting, delamination and surface cracking. In vivo hydrogen embrittlement was shown to be a mechanism of degradation in modular connections resulting from electrochemical reactions induced in the crevice environment of the tapers during fretting-crevice corrosion.
Rodrigues, Danieli C.; Urban, Robert M.; Jacobs, Joshua J.; Gilbert, Jeremy L.
A prospective, randomized, controlled trial was conducted to compare clinical outcomes in patients treated with an investigational interspinous spacer (Superion) versus those treated with an FDA-approved spacer (X-STOP). One hundred sixty-six patients with moderate lumbar spinal stenosis (LSS) unresponsive to conservative care were treated randomly with the Superion (n = 80) or X-STOP (n = 86) interspinous spacer. Study subjects were followed through 6 months posttreatment. Zurich Claudication Questionnaire (ZCQ) symptom severity scores improved 30% with Superion and 25% with X-STOP (both P < 0.001). Similar changes were noted in ZCQ physical function with improvements of 32% with Superion and 27% with X-STOP (both P < 0.001). Mean ZCQ patient satisfaction score ranged from 1.7 to 2.0 in both groups at all follow-up visits. The proportion of subjects that achieved at least two of three ZCQ clinical success criteria at 6 months was 75% with Superion and 67% with X-STOP. Axial pain decreased from 55 ± 27?mm at pretreatment to 22 ± 26?mm at 6 months in the Superion group (P < 0.001) and from 54 ± 29?mm to 32 ± 31?mm with X-STOP (P < 0.001). Extremity pain decreased from 61 ± 26?mm at pretreatment to 18 ± 27?mm at 6 months in the Superion group (P < 0.001) and from 64 ± 26?mm to 22 ± 30?mm with X-STOP (P < 0.001). Back function improved from 38 ± 13% to 21 ± 19% with Superion (P < 0.001) and from 40 ± 13% to 25 ± 16% with X-STOP (P < 0.001). Preliminary results suggest that the Superion interspinous spacer and the X-STOP each effectively alleviate pain and improve back function in patients with moderate LSS who are unresponsive to conservative care.
Miller, Larry E.; Block, Jon E.
A prospective, randomized, controlled trial was conducted to compare clinical outcomes in patients treated with an investigational interspinous spacer (Superion) versus those treated with an FDA-approved spacer (X-STOP). One hundred sixty-six patients with moderate lumbar spinal stenosis (LSS) unresponsive to conservative care were treated randomly with the Superion (n = 80) or X-STOP (n = 86) interspinous spacer. Study subjects were followed through 6 months posttreatment. Zurich Claudication Questionnaire (ZCQ) symptom severity scores improved 30% with Superion and 25% with X-STOP (both P < 0.001). Similar changes were noted in ZCQ physical function with improvements of 32% with Superion and 27% with X-STOP (both P < 0.001). Mean ZCQ patient satisfaction score ranged from 1.7 to 2.0 in both groups at all follow-up visits. The proportion of subjects that achieved at least two of three ZCQ clinical success criteria at 6 months was 75% with Superion and 67% with X-STOP. Axial pain decreased from 55 ± 27?mm at pretreatment to 22 ± 26?mm at 6 months in the Superion group (P < 0.001) and from 54 ± 29?mm to 32 ± 31?mm with X-STOP (P < 0.001). Extremity pain decreased from 61 ± 26?mm at pretreatment to 18 ± 27?mm at 6 months in the Superion group (P < 0.001) and from 64 ± 26?mm to 22 ± 30?mm with X-STOP (P < 0.001). Back function improved from 38 ± 13% to 21 ± 19% with Superion (P < 0.001) and from 40 ± 13% to 25 ± 16% with X-STOP (P < 0.001). Preliminary results suggest that the Superion interspinous spacer and the X-STOP each effectively alleviate pain and improve back function in patients with moderate LSS who are unresponsive to conservative care. PMID:22448323
Miller, Larry E; Block, Jon E
The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.
Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew
The influence of carbon (C) content, microstructure, crystallography and mechanical properties on the wear behaviour of metal-on-metal (MM) hip implants made from commercially available cobalt-chromium-molybdenum (CoCrMo) alloys designated as American Society of Testing and Materials (ASTM) grade F1537, F75 and as-cast were studied in this work. The as-received bars of wrought CoCrMo alloys (ASTM F1537 of either about 0.05% or 0.26% C) were each subjected to various heat treatments to develop different microstructures. Pin and plate specimens were fabricated from each bar and were tested against each other using a linear reciprocating pin-on-plate apparatus in 25% by volume bovine serum solution. The applied normal load was 9.81 N and the reciprocating plate had a sinusoidal velocity with an average speed of 26 mm/s. The wear was measured gravimetrically and it was found to be most strongly affected by alloy C content, irrespective of grain size or carbide morphology. More precisely, the wear behaviour was directly correlated to the dissolved C content of the alloys. Increased C in solid-solution coincided with lower volumetric wear since C helps to stabilize the face-centred cubic (FCC) crystal structure thus limiting the amount of strain induced transformation (SIT) to the hexagonal close-packed crystal structure (HCP). Based on the observed surface twinning in and around the contact zone and the potentially detrimental effect of the HCP phase, it was postulated that the MM wear behaviour of CoCrMo alloys in the present study was controlled by a deformation mechanism, rather than corrosion or tribochemical reactions.
Infection remains a serious complication after total hip arthroplasty (THA) and is a leading cause of hip revision surgery. It is currently accepted that removal of the prosthesis is essential to curing an infection when facing chronic PJIs with prosthesis loosening. In order to avoid the disadvantages of a two-stage approach, some authors have proposed a one-stage hip revision for the treatment of hip prosthesis infection in selected patients using not only antibiotic-loaded cemented components but also cementless implant. In the case of a one-stage procedure, the patient is exposed to a single major procedure and therefore lower cumulative perioperative risk. A functional prosthesis replacement is completed without exposure to the complications associated with spacers. In addition, there are also benefits both financially and in terms of resource allocation.
Munoz-Mahamud, Ernesto; Gallart, Xavier; Soriano, Alejandro
Background - The mechanism of failure of metal-on-metal (MoM) total hip arthroplasty (THA) has been related to a high rate of metal wear debris, which is partly generated from the head-trunnion interface. However, it is not known whether implant fixation is affected by metal wear debris. Patients and methods - 49 cases of MoM THA in 41 patients (10 women) with a mean age of 52 (28-68) years were followed with stereoradiographs after surgery and at 1, 2, and 5 years to analyze implant migration by radiostereometric analysis (RSA). Patients also participated in a 5- to 7-year follow-up with measurement of serum metal ions, questionnaires (Oxford hip score (OHS) and Harris hip score (HHS)), and measurement of cup and stem positions and systemic bone mineral density. Results - At 1-2 years, mean total translation (TT) was 0.04 mm (95% CI: -0.07 to 0.14; p = 0.5) for the stems; at 2-5 years, mean TT was 0.13 mm (95% CI: -0.25 to -0.01; p = 0.03), but within the precision limit of the method. For the cups, there was no statistically significant TT or total rotation (TR) at 1-2 and 2-5 years. At 2-5 years, we found 4 cups and 5 stems with TT migrations exceeding the precision limit of the method. There was an association between cup migration and total OHS < 40 (4 patients, 4 hips; p = 0.04), but there were no statistically significant associations between cup or stem migration and T-scores < -1 (n = 10), cup and stem positions, or elevated serum metal ion levels (> 7µg/L (4 patients, 6 hips)). Interpretation - Most cups and stems were well-fixed at 1-5 years. However, at 2-5 years, 4 cups and 5 stems had TT migrations above the precision limits, but these patients had serum metal ion levels similar to those of patients without measurable migrations, and they were pain-free. Patients with serum metal ion levels > 7 µg/L had migrations similar to those in patients with serum metal ion levels < 7 µg/L. Metal wear debris does not appear to influence the fixation of hip components in large-head MoM articulations at medium-term follow-up. PMID:24847790
Hjorth, Mette Holm; Søballe, Kjeld; Jakobsen, Stig Storgaard; Lorenzen, Nina Dyrberg; Mechlenburg, Inger; Stilling, Maiken
This patent describes a method for cementing a wellbore penetrating an earth formation into which a conduit extends, the wellbore having a space occupied by a drilling fluid. It comprises displacing the drilling fluid from the space with a spacer fluid comprising: sulfonated styrene-maleic anhydride copolymer, bentonite, welan gum, surfactant and a weighting agent; and displacing the spacer composition and filling the wellbore space with a settable cement composition.
Wilson, W.N.; Bradshaw, R.D.; Wilton, B.S.; Carpenter, R.B.
The contact mechanics in metal-on-metal hip implants employing a cobalt chromium acetabular cup with an ultra-high molecular weight polyethylene (UHMWPE) backing were analysed in the present study using the finite element method. A general modelling methodology was developed to examine the effects of the interfacial boundary conditions between the UHMWPE backing and a titanium shell for cementless fixation, the coefficient of friction and the loading angle on the predicted contact pressure distribution at the articulating surfaces. It was found that the contact mechanics at the bearing surfaces were significantly affected by the UHMWPE backing. Consequently, a relatively constant pressure distribution was predicted within the contact conjunction, and the maximum contact pressure occurred towards the edge of the contact. On the other hand, the interfacial boundary condition between the UHMWPE backing and the titanium shell, the coefficient of friction and the loading angle were found to have a negligible effect on the contact mechanics at the bearing surfaces. Overall, the magnitude of the contact pressure was significantly reduced, compared with a similar cup without the UHMWPE backing. The importance of the UHMWPE backing on the tribological performance of metal-on-metal hip implants is discussed. PMID:12807161
Liu, F; Jin, Z M; Grigoris, P; Hirt, F; Rieker, C
Prostheses alter the loading pattern in bones. For example femoral hip implants cause the cortical bone to remodel and the implant\\/bone interface to react. To date, simulations of peri-prosthetic bone adaptations have succeeded for the bulk bone remodelling only. In this study we use an approach based on a combined strain\\/damage algorithm to simultaneously predict both bulk and interfacial peri-prosthetic
Paul T. Scannell; Patrick J. Prendergast
Fracture around the acetabulum and femur in total hip arthroplasty is a possible complication, sometimes with difficult surgical solution, namely when a sepsis is present. Periprosthetic hip fractures were classified according to a modified Vancouver classification. We treated 112 patients (67 men and 45 women) with periprosthetic hip fractures: 105 femoral fractures (94%) and seven acetabular fractures (6%). Mean follow-up was 10.6 years. For Type A (seven cases - 7%), B1 (10 cases - 10%) or C (13 cases - 12%) fractures around well fixed femoral stems we only fixed the fractures. For Type B2 (17 cases - 16%), B3 (46 cases - 44%) and D (12 cases - 11%, with associated fractures, not contemplated in the Vancouver classification) we used an uncemented long femoral stem, fixation with metallic cables and cancellous bone allografts to fill the femoral bone loss. We observed a deep infection in three patients (2.7%), three early hip dislocations treated by closed reductions, two cases with asymptomatic trochanteric non-union and one femoral refracture. In the three infection cases we performed two-stage revision with cementless hip prosthesis, using an antibiotic-loaded cement hip spacer (three to eight months), a six weeks period of parenteral antibiotics and we performed articular aspiration before revision surgery. Until now, we did not observe any re-infection. It is very important to make an early diagnosis, isolate micro-organisms and ensure their antibiotic susceptibility. The surgery solution depends on the well fixed implants and periprosthetic osteolysis and articular instability. PMID:22956376
Migration of the acetabular and femoral implants after THR is a better index of the stability of the bone-implant interfaces than are clinical or radiological results. Roentgenstereophotogrammetry (RSA) studies 3-D migration of the implants with high accuracy (0.15 to 0.28 mm for linear migrations). RSA presents several drawbacks which restrict its use to prospective studies on small numbers of patients. Simpler methods have therefore been developed to assess 2-D migration on standard films in retrospective studies. The precision of these "simple" methods is limited, due to several factors: the difficulty to define reliable landmarks on femur or pelvis, sometimes even on implants, measurement errors, related to variations in radiographic technique (focal distance, beam centering, patient positioning). Sutherland, Wetherell and Nunn have proposed methods with an accuracy around 2-3 mm. It appears impossible to correct migration measurements for distorsions due to patient positioning; the EBRA method was therefore developed to reject non-comparable films using a comparability algorithm. A precision of 0.20 to 0.32 mm can thus be reached for the study of cup migration. The same pitfalls are encountered in assessment of migration of the femoral implant; a preliminary theoretical study is mandatory for every implant studied. The data presently available show that migration at 2 years is predictive of the long-term evolution of an implant; for the cup, migration of 1 mm or more at 2 years is predictive of late failure, and similar conclusions can be drawn regarding the femoral implant. The 2-D assessment of implant migration using a correct "simple" method provides a mean to evaluate a new implant or an innovative technical modification in a reasonable amount of time, on a limited number of patients. PMID:9148637
Lemaire, R; Rodriguez, A
Background Modular neck adapters for hip arthroplasty stems allow the surgeon to modify CCD angle, offset and femoral anteversion intraoperatively. Fretting or crevice corrosion may lead to failure of such a modular device due to high loads or surface contamination inside the modular coupling. Unfortunately we have experienced such a failure of implants and now report our clinical experience with the failures in order to advance orthopaedic material research and joint replacement surgery. The failed neck adapters were implanted between August 2004 and November 2006 a total of about 5000 devices. After this period, the titanium neck adapters were replaced by adapters out of cobalt-chromium. Until the end of 2008 in total 1.4% (n = 68) of the implanted titanium alloy neck adapters failed with an average time of 2.0 years (0.7 to 4.0 years) postoperatively. All, but one, patients were male, their average age being 57.4 years (36 to 75 years) and the average weight 102.3 kg (75 to 130 kg). The failures of neck adapters were divided into 66% with small CCD of 130° and 60% with head lengths of L or larger. Assuming an average time to failure of 2.8 years, the cumulative failure rate was calculated with 2.4%. Methods A series of adapter failures of titanium alloy modular neck adapters in combination with a titanium alloy modular short hip stem was investigated. For patients having received this particular implant combination risk factors were identified which were associated with the occurence of implant failure. A Kaplan-Meier survival-failure-analysis was conducted. The retrieved implants were analysed using microscopic and chemical methods. Modes of failure were simulated in biomechanical tests. Comparative tests included modular neck adapters made of titanium alloy and cobalt chrome alloy material. Results Retrieval examinations and biomechanical simulation revealed that primary micromotions initiated fretting within the modular tapered neck connection. A continuous abrasion and repassivation process with a subsequent cold welding at the titanium alloy modular interface. Surface layers of 10 - 30 ?m titanium oxide were observed. Surface cracks caused by fretting or fretting corrosion finally lead to fatigue fracture of the titanium alloy modular neck adapters. Neck adapters made of cobalt chrome alloy show significantly reduced micromotions especially in case of contaminated cone connection. With a cobalt-chromium neck the micromotions can be reduced by a factor of 3 compared to the titanium neck. The incidence of fretting corrosion was also substantially lower with the cobalt-chromium neck configuration. Conclusions Failure of modular titanium alloy neck adapters can be initiated by surface micromotions due to surface contamination or highly loaded implant components. In the present study, the patients at risk were men with an average weight over 100 kg. Modular cobalt chrome neck adapters provide higher safety compared to titanium alloy material.
Infection of a total hip replacement (THR) is considered a devastating complication, necessitating its complete removal and thorough debridement of the site. It is undoubted that one stage exchange, if successful, would provide the best benefit both for the patient and the society. Still the fear of re-infection dominates the surgeons´ decisions and in the majority of cases directs them to multiple stage protocols. However, there is no scientifically based argument for that practice. Successful eradication of infection with two stage procedures is reported to average 80% to 98%. On the other hand a literature review of Jackson and Schmalzried (CORR 2000) summarizing the results of 1,299 infected hip replacements treated with direct exchange (almost exclusively using antibiotic loaded cement), reports of 1,077 (83%) having been successful. The comparable results suggest, that the major factor for a successful outcome with traditional approaches may be found in the quality of surgical debridement and dead space management. Failures in all protocols seem to be caused by small fragments of bacterial colonies remaining after debridement, whereas neither systemic antibiotics nor antibiotic loaded bone cement (PMMA) have been able to improve the situation significantly. Reasons for failure may be found in the limited sensitivity of traditional bacterial culturing and reduced antibiotic susceptibility of involved pathogens, especially considering biofilm formation. Whenever a new prosthesis is implanted into a previously infected site the surgeon must be aware of increased risk of failure, both in single or two stage revisions. Eventual removal therefore should be easy with low risk of additional damage to the bony substance. On the other hand it should also have potential of a good long term result in case of success. Cemented revisions generally show inferior long term results compared to uncemented techniques; the addition of antibiotics to cement reduces its biomechanical properties. Efficient cementing techniques will result in tight bonding with the underlying bone, making eventual removal time consuming and possibly associated with further damage to the osseous structures. All these issues are likely to make uncemented revisions more desirable. Allograft bone may be impregnated with high loads of antibiotics using special incubation techniques. The storage capacities and pharmacological kinetics of the resulting antibiotic bone compound (ABC) are more advantageous than the ones of antibiotic loaded cement. ABC provides local concentrations exceeding those of cement by more than a 100fold and efficient release is prolonged for several weeks. The same time they are likely to restore bone stock, which usually is compromised after removal of an infected endoprosthesis. ABC may be combined with uncemented implants for improved long term results and easy removal in case of a failure. Specifications of appropriate designs are outlined. Based on these considerations new protocols for one stage exchange of infected TJR have been established. Bone voids surrounding the implants may be filled with antibiotic impregnated bone graft; uncemented implants may be fixed in original bone. Recent studies indicate an overall success rate of more than 90% without any adverse side effects. Incorporation of allografts appears as after grafting with unimpregnated bone grafts. Antibiotic loaded bone graft seems to provide sufficient local antibiosis for protection against colonisation of uncemented implants, the eluted amounts of antibiotics are likely to eliminate biofilm remnants, dead space management is more complete and defects may be reconstructed efficiently. Uncemented implants provide improved long term results in case of success and facilitated re-revision in case of failure. One stage revision using ABC together with uncemented implants such should be at least comparably save as multiple stage procedures, taking advantage of the obvious benefits for patients and economy.
Reconstruction for concurrent infection of an ipsilateral total hip arthroplasty (THA) and total knee arthroplasty (TKA) is a challenge. We report a 2-stage reconstruction of a THA for chronic infection of both the THA and TKA with severe femoral bone loss secondary to interprosthetic fractures. The reconstruction involved using a custom-made, temporary, antibiotic-impregnated PROSTALAC spacer mated with an intramedullary nail. The acetabulum was then exposed and the necrotic cartilage was removed and curetted. The acetabulum was reamed to accept a PROSTALAC acetabular shell. The shell was cemented into the acetabulum with antibiotic cement. The custom-made spacer was then inserted distally first into the tibia. The distal end of the intramedullary nail was interlocked with a bicortical bolt to minimise nail rotation. Antibiotic-impregnated cement was moulded around the nail and spacer. The proximal end of the spacer was then reduced into the acetabular socket, and the joint was irrigated and the wound closed. A customised abduction brace was fitted, and partial weight bearing was allowed. Sufficient leg length, soft-tissue tension, and range of hip motion were restored, and a total femur and constrained liner was re-implanted 4 months later. Mating of an intramedullary nail with a PROSTALAC spacer is a viable reconstructive option. PMID:22933694
Kamath, Atul F; Austin, Daniel; Lee, Gwo-Chin
Large-diameter metal-on-metal articulations may provide an opportunity for wear reduction in total hip implants because earlier studies have shown that the formation of a fluid film that completely separates the bearing surfaces is theoretically possible. In such a lubrication mode and under ideal conditions, there is theoretically no amount of wear. Studies have suggested that the two primary parameters controlling the lubrication mode are the diameter and the clearance of the articulation. The goal of the present study was to experimentally investigate the influence of these two parameters on the wear behavior of large-diameter metal-on-metal articulations pertaining to resurfacing hip implants. The results of this in vitro investigation showed that longer running-in periods and higher amounts of running-in wear were associated with larger clearances. PMID:15833451
Rieker, Claude B; Schön, Rolf; Konrad, Reto; Liebentritt, Gernot; Gnepf, Patric; Shen, Ming; Roberts, Paul; Grigoris, Peter
Patient-specific finite element models of the implanted proximal femur can be built from pre-operative computed tomography scans and post-operative X-rays. However, estimating three-dimensional positioning from two-dimensional radiographs introduces uncertainty in the implant position. Further, accurately measuring the thin cement mantle and the degree of cement-bone interdigitation from imaging data is challenging. To quantify the effect of these uncertainties in stem position and cement thickness, a sensitivity study was performed. A design-of-experiment study was implemented, simulating both gait and stair ascent. Cement mantle stresses and bone-implant interface strains were monitored. The results show that small variations in alignment affect the implant biomechanics, especially around the most proximal and most distal ends of the stem. The results suggest that implant position is more influential than cement thickness. Rotation around the medial-lateral axis is the dominant factor in the proximal zones and stem translations are the dominant factors around the distal tip. PMID:23405986
Shi, J; Browne, M; Strickland, M; Flivik, G; Taylor, M
The metal-on-metal bearing total hip prosthesis is expected to reduce the risk of debris-related osteolysis. However, several reports demonstrated that the socket-stem impingement in the metal-on-metal prosthesis due to the implant malposition results in titanium wear debris and secondary metallosis. In this article, we presented a case of massive metallosis due to metal-on-metal impingement. A 60-year woman had severe hip pain due to fracture of the greater trochanter. We planned a revision of the metal-on-metal inlay. Intraoperatively, the trochanteric bursa and joint space were found to be stained black. Black stained granulation tissue was observed between the femoral stem and the great trochanter. Intraoperatively, notching was noticed on both the posteroinferior aspect of the neck of the femoral component and the anterior aspect of the metal liner and polyethylene core. The notch corresponded to the position of impingement between the socket and the femoral neck during the maximum extension of the hip. To clarify the mechanism of cup-neck impingement, the alignment of the prosthesis and pelvic tilt were evaluated. The cup was placed in too much anteverted position. In addition, increased posterior tilt of pelvis in the standing position made the anteversion of the acetabular cup more significant, which enhanced the cup-neck impingement during the gait. Careful attention is necessary for implant alignment and pelvic tilt especially in metal-on-metal-bearing total hip arthroplasty. PMID:19292272
Onda, Kazunori; Nagoya, Satoshi; Kaya, Mitsunori; Yamashita, Toshihiko
A spacer for use in a fuel assembly of a nuclear reactor having thin, full-height divider members, slender spring members and laterally oriented rigid stops and wherein the total amount of spacer material, the amount of high neutron cross section material, the projected area of the spacer structure and changes in cross section area of the spacer structure are minimized whereby neutron absorption by the spacer and coolant flow resistance through the spacer are minimized.
Curulla, M. V.; Brayman, K. W.; Matzner, B.; Price, T. F.; Qurnell, F. D.
Gold bead implantation/gold acupuncture is becoming increasingly used in veterinary medicine as a method of pain treatment in cases of osteoarthritic diseases. Part one of the overview dealing with the use of gold implants as a treatment of canine hip joint dysplasia (cHD) introduced the method of implanting gold in tissue and publications which investigated the subsequent effects of implantation. This article focuses on publications concerning the clinical effectiveness of gold implantation within the scope of pain therapy in cHD. Due to the study design, a classification using evidence-based levels (EbL) was carried out. Three double-blind, placebo-controlled randomised studies (EbL II) were considered together with three retrospective studies on own patients (EbL IV) and five case studies (EbL IV). While the case and retrospective studies reported impressive therapeutic success in treating cHD-incurred pain with gold implantation, a pain-reducing effect through gold implantation was only demonstrated in one of the three double-blind studies. The two remaining EbL II studies found no differences between the placebo-group and the group of dogs treated with gold implantation. In one of these two studies, kinematic and kinetic gait analyses were used for objective evaluation of the effects of the treatment. Thus, the only study that carried out an objective evaluation of the therapeutic result of gold implantation came to the conclusion that the method is ineffective. For a concluding assessment of gold implantation in the case of cHD, gait analysis studies investigating the effects of gold implantation in comparison to a standard treatment with nonsteroidal anti-inflammatory drugs are currently lacking. PMID:23958708
Deisenroth, A; Nolte, I; Wefstaedt, P
Corrosion at the modular neck-stem taper junction has become an increasingly important topic as several reports have identified this couple as a possible source for early failure with findings similar to failed metal-on-metal hip arthroplasties. Recently, two different modular stem systems from a single manufacturer were voluntarily recalled due to concerns of failure of the modular taper junction. We discuss how to approach the diagnosis and management of patients with these particular stem systems. We further reviewed the literature to evaluate whether this is a manufacturer-specific defect or indicative of a broader trend. Recent studies appear to implicate the basic design of the neck-stem taper junction, rather than a single manufacturer, which is at high risk for fretting and corrosion. PMID:24090661
Pivec, Robert; Meneghini, R Michael; Hozack, William J; Westrich, Geoffrey H; Mont, Michael A
Objective. To compare two internal fixation devices clinically in stabilisation of intertrochanteric femur fractures. Methods. Eighty-seven patients were randomised upon their admission to the hospital using a sealed envelope method. Forty-five were treated with proximal femur nail antirotation (PFNA) and 42 with reverse less invasive stabilisation system (LISS). The perioperative data were recorded and compared in relation to fracture type. Results. In each type of fractures, no significant differences were found with respect to the blood loss, the quality of reduction, the time to bony healing, and the Harris hip score between the 2 groups. The mean duration of surgery was significantly longer in reverse LISS group than in PFNA group. Conclusion. Both the PFNA and the reversed LISS are effective in the treatment of different types of intertrochanteric femur fractures. PFNA is superior to reverse LISS in terms of surgical time, weight-bearing, and perhaps fluoroscopy time.
Tao, Ran; Lu, Yue; Xu, Hua; Zhou, Zhen-Yu; Wang, You-Hua; Liu, Fan
This work is based upon an experimental simulation of one-legged stance, under loads close to the average body weight. Skeletons, harvested from fresh non-embalmed cadavers, included pelvis, two lumbar vertebrae, and both femurs. Periacetabular deformations were studied using tridirectional strain gauges before and after implantation of different types of acetabular prostheses in eight pelves: conventional polyethylene-cemented sockets, polyethylene sockets cemented
P. Massin; E. Vandenbussche; B. Landjerit; B. Augereau
Retrograde tibiotalocalcaneal nailing arthrodesis has proved to be a viable salvage procedure; however, extended bone loss around the ankle has been associated with high rates of nonunion and considerable shortening of the hindfoot. We present the surgical technique and the first 2 cases in which a trabecular metal™ interpositional spacer, specifically designed for tibiotalocalcaneal nailing arthrodesis, was used. The spacer can be implanted using either an anterior or a lateral approach. An integrated hole in the spacer allows a retrograde nail to be inserted, which provides excellent primary stability of the construct. Trabecular metal™ is a well-established and well-described material used to supplement deficient bone stock in surgery of the spine, hip, and knee. It has shown excellent incorporation and reduces the need for auto- and allografts. The trabecular metal™ interpositional ankle spacer is the first trabecular metal spacer designed specifically for ankle surgery. Its shape and variable size will make it a valuable tool for reconstructing bone loss in tibiotalocalcaneal nailing arthrodesis. PMID:24666978
Horisberger, Monika; Paul, Jochen; Wiewiorski, Martin; Henninger, Heath B; Khalifa, Muhammad S; Barg, Alexej; Valderrabano, Victor
This study assesses the factors associated with the dislocation of the Spacer-G and its clinical prognosis. Seventy-four spacers were reviewed. Acetabular bone defects, proximal femoral cementation of the spacer and its relationship to the size of the head spacer were not associated with dislocation. The only variable that it was possible to associate with dislocation was when the previous stem, prior to the spacer placement, was a cemented stem. In patients who experienced a dislocation, infection was not cured during the interim period more frequently than patients who had not experienced a dislocation (P = 0.001) and the final clinical hip evaluation was also worse (P < 0.001). The study concludes that the surgeon should assess different surgical aspects in order to avoid mechanical complications such as dislocation and its consequences. PMID:24269066
Bori, Guillem; García-Oltra, Ester; Soriano, Alex; Rios, José; Gallart, Xavier; Garcia, Sebastian
We report two cases of acute infection of an uncemented femoral component in a hip prosthesis implanted after external fixation of a femoral fracture. In both cases, the surgical access did not cross over the pin scars. When the prosthesis was implanted the stem crossed one or more pin tracts. The preoperative clinical examination, laboratory tests and bone scintigraphy with marked granulocytosis did not show signs of local infection in either case. We suggest that every patient destined to receive a prosthesis after external fixation should be treated with a staged procedure, the first step being excision of the soft tissues around the pin tracts and curettage or drilling of the bony holes, followed by prosthesis implant.
Masse, A.; Guzzi Susini, E.
Introduction The use of metal-on-metal (MoM) total hip arthroplasty (THA) increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds) in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. Objective To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. Methods Systematic review of clinical trials (RCTs) and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum) in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor), patient characteristics as well as study quality characteristics (secondary explanatory factors). Results Overall, 104 studies (11 RCTs, 93 epidemiological studies) totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine) irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L). Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. Discussion Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed „time out“ for stemmed large-head MoM-THA and recommend a restricted indication for hip resurfacing arthroplasty. Patients with implanted MoM-bearing should receive regular and standardized monitoring of metal ion concentrations. Further research is indicated especially with regard to potential systemic reactions due to accumulation of metal products.
Hartmann, Albrecht; Hannemann, Franziska; Lutzner, Jorg; Seidler, Andreas; Drexler, Hans; Gunther, Klaus-Peter; Schmitt, Jochen
Prostheses alter the loading pattern in bones. For example femoral hip implants cause the cortical bone to remodel and the implant/bone interface to react. To date, simulations of peri-prosthetic bone adaptations have succeeded for the bulk bone remodelling only. In this study we use an approach based on a combined strain/damage algorithm to simultaneously predict both bulk and interfacial peri-prosthetic bone adaptation around a non-cemented hip prosthesis. The influence of stem stiffness is investigated; a flexible iso-elastic stem (20GPa), an titanium alloy stem (110GPa), and a stiff cobalt chrome (CoCrMo) stem (210GPa). The results predict that an iso-elastic stem reduces proximal bone loss because stress shielding is prevented but it increases proximal interface resorption due to damage-stimulated resorption. On the other hand, a stiff cobalt chrome stem increases proximal strain-stimulated resorption but does not induce proximal interfacial damage-stimulated resorption; however damage-stimulated resorption surrounding the distal tip is predicted to increase with stiffer stems. Simulations for the titanium stem were predicted to minimise both strain and damage related remodelling. We propose that this combined strain/damage remodelling algorithm can provide realistic simulations of the response of bone around load-bearing orthopaedic implants. PMID:19188086
Scannell, Paul T; Prendergast, Patrick J
This patent describes an improved floating spacer grid in combination with a nuclear fuel assembly of the type having parallel fuel rods and at least one guide tube maintained in a laterally spaced array by axially spaced spacer grids. The fuel rods and guide tube extend through the spacer grids. The guide tube has a uniform circular outer surface, the spacer grids are movably mounted to the guide tube to permit axial displacement of the spacer grids relative the guide tube. Saddles form from and within the spacer grids at top and bottom edges of the grids, a spacer sleeve positioned concentrically about the guide tube intermediate the adjacent ones of the axially-spaced spacer grids for limiting axial displacement of the spacer grids, and the spacer sleeve has opposite ends closely spaced from the edges of the adjacent spacer grids to define a displacement space. The improvement comprises in combination; tubular inserts, each insert mounted to the guide tube within each of the spacer grids. Each insert includes a tubular portion positioned by the saddles to circumscribe the guide tube within the spacer grid and a circular flange portion at one end of the tubular portion. The flange portion is positioned in the displacement space and abutted to the edge of the spacer grid on the saddles, intermediate the spacer grid and spacer sleeve, and the circular flange portion has substantially the same outer diameter as the spacer sleeve thus precluding direct contact of the spacer sleeve with the spacer grid. The inserts carry all axial through-grid loads and prevent a horizontal vector force component applied against the grids.
King, R.A.; Larson, J.G.; Walton, L.A.
Introduction The aim of our study was to investigate a potential influence of elevated serumcobalt and serumchromiumlevels on renal function\\u000a at minimum 10 years after implantation of a metal-on-metal hip.\\u000a \\u000a \\u000a \\u000a Materials and methods Between November 1992 and June 1994 98 patients (44 m, 54 f) with an average age of 56 (22–79) years received a metal-on-metal\\u000a bearing Metasul™. At the time of the 10-year follow-up,
Martina Marker; Alexander Grübl; Otto Riedl; Georg Heinze; Erich Pohanka; Rainer Kotz
Introduction We conducted a prospective study to compare the exposure and implant positioning in primary total hip replacement through\\u000a the anterolateral minimally invasive (ALMI) approach versus the posterior minimally invasive (PMI) approach.\\u000a \\u000a \\u000a \\u000a Materials and methods We applied these techniques to 2 consecutive groups (33 and 43 patients, respectively) comparable preoperatively. All the\\u000a patients received the same cementless stem and acetabular component.\\u000a \\u000a \\u000a \\u000a Results There
Jean-Michel Laffosse; Franck Accadbled; François Molinier; Philippe Chiron; Bensafi Hocine; J. Puget
Background Culturing of the sonication fluid of removed implants has proven to be more sensitive than conventional periprosthetic tissue culture for the microbiological diagnosis of prosthetic joint infection. Since bacteria surviving on antibiotic-loaded cement spacers used in a two-stage exchange protocol for infected arthroplasties may cause the persistence of infection, in this study we asked whether the sonication also could be used to identify bacteria on antibiotic-loaded cement spacers removed at the second surgical stage during a two-stage exchange procedure to confirm whether or not the prosthetic joint infection had been eradicated. Methods We cultured the sonication fluid of cement spacers that had been originally implanted in a two-stage exchange protocol in 21 patients (mean age, 66 years) affected by prosthetic joint infection (16 total knee prostheses and 5 hip prostheses). The cement spacers were vortexed for 30 seconds and then subjected to sonication (frequency 35–40 KHz). The resulting sonicate fluid was cultured for aerobic and anaerobic bacteria. Results The sonication fluid culture of the removed spacer was positive in six patients (29%), with isolation of methicillin-sensible Staphylococcus Aureus (MSSA) in three cases, methicillin-resistant Staphylococcus Aureus (MRSA) in one case and Pseudomonas Aeruginosa in two cases. In three of these positive cases, the traditional culture of periprosthetic tissue was negative. Two patients with positive sonication culture of the spacer were successfully treated by early debridement of the revision prosthesis and systemic antibiotic therapy. In three patients a knee arthrodesis was planned and performed as the second surgical stage. In two of them the infection was caused by highly resistant Pseudomonas Aeruginosa. The other patient with a MSSA infection had been poorly compliant with the systemic antibiotic therapy due to her mental impairment. The patient originally affected by MRSA infection of his primary hip arthroplasty developed recurrent infection of his revision prosthesis and eventually underwent Girdlestone arthroplasty. Conclusions The sonication culture can be used to discover any bacteria on the antibiotic-loaded cement spacer during a two-stage exchange protocol, thus permitting the adoption of timely treatment options, such as the early prosthetic debridment.
This patent describes an improved floating spacer grid in combination with a nuclear fuel assembly of the type having parallel fuel rods and at least one guide tube maintained in a laterally spaced array by axially spaced spacer grids. The fuel rods and guide tube extend through the spacer grids. The guide tube has a uniform circular outer surface, the
R. A. King; J. G. Larson; L. A. Walton
\\u000a The surface replacement of the hip as an alternative method to the implantation of a conventional hip prosthesis seems to\\u000a be advantageous in consideration to bone conservation particularly for young patients.
S. Goebel; M. Blanke; Ch. Hendrich
Background and purpose Two-stage reconstruction, reimplantation after removal of an infected prosthesis, has been considered to be the gold standard for treatment of infected hip arthroplasty. However, during the removal of a well-fixed femoral stem, the proximal femur can be damaged and a sequestrum can be formed, which might lead to chronic osteomyelitis and difficulty in reimplantation. We wanted to determine whether infection after hip arthroplasty can be treated without removal of a well-fixed stem. Methods We treated 19 patients who had an infection after hip replacement, but a well-fixed cementless stem, with 2-stage reconstruction. At the first stage, we removed the acetabular cup, the liner and the head, but not the stem. We then implanted a cup of cement spacer. After control of infection, we reimplanted the acetabular component and head. Results 2 patients did not undergo second-stage reconstruction because they were satisfied with the pain relief and the activity that they had with the cement-spacer implantation. The remaining 17 patients underwent the second-stage of the reconstruction using cementless arthroplasty. At a mean follow-up time of 4 (2–8) years, 15 of the patients had no recurrence of infection, with satisfactory clinical and radiographic outcome. Interpretation This second-stage reconstruction after retention of the stem could be an alternative treatment option for periprosthetic infection with a well-fixed stem.
The optimal implant option for hip arthroplasty in the young, active patient remains controversial. There has been renewed\\u000a interest for metal-on-metal hip resurfacing due to improved design and manufacturing of implants, better materials, enhanced\\u000a implant fixation, theoretical advantages over conventional total hip arthroplasty, and recent Food and Drug Administration\\u000a approval of two devices. Recent studies indicate satisfactory short- and midterm
Ryan M. Nunley; Craig J. Della Valle; Robert L. Barrack
The purpose of the OCH module spacers is to keep the given dimension of .224-inch between the 1.83-inch absorber plates. This distance is determined by two liquid argon gaps of .09-inch each and a readout board of .044-inch. The spacer should be made out of a material that would give a minimum thermal contraction movement. Also the dimension of the spacer will be determined dependent upon the load applied to the spacers and the strength of the material chosen. Considering both thermal contraction and yield strength, it is found that Invar-36 would be a suitable material from which to make the spacers for the OCh module, provided that SS304 washers are used in conjunction with the spacers. The spacers would be positioned about 1-inch from the corners of each of the copper plates, and would have a diameter of about 0.85453399-inch. The thickness of the Invar spacer would be 0.15394250-inch and that of the SS304 would be 0.07005750-inch. This combination of materials used for spacing purposes should result in zero displacement due to thermal contraction and no buckling due to overloading. The actual design of the spacer can be found in DWG.
Kurita, C.H.; /Fermilab
It has been suggested that corrosion and fretting at the tapered, modular junctions of hip arthroplasties may contribute to implant failure. In this study the reliability of a commonly used peer-reviewed scoring system for visual assessment of corrosion and fretting at these junctions was evaluated. Volumetric material loss at the tapered head surface was measured and associations with the visual scores were investigated. We found that the inter-observer reproducibility and single-observer repeatability of the corrosion scores were substantial using Cohen's weighted Kappa statistic (k = 0.64-0.71). The reproducibility and repeatability of the fretting scores however were slight to fair (k = 0.18-0.31). Taper corrosion scores were significantly and moderately correlated with the volume of material loss measured (Spearman's r = 0.59; P < 0.001). We recommend the continued use of this scoring system but it should not be a substitute for measurement of material loss. PMID:24411082
Hothi, Harry S; Matthies, Ashley K; Berber, Reshid; Whittaker, Robert K; Skinner, John A; Hart, Alister J
Introduction Between 12% and 37% of people will die in the year after a hip fracture, and 10% to 20% of survivors will move into a more dependent residence. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of surgical interventions in people with hip fracture? What are the effects of perisurgical medical interventions on surgical outcome and prevention of complications in people with hip fracture? What are the effects of rehabilitation interventions and programmes after hip fracture? We searched: Medline, Embase, The Cochrane Library, and other important databases up to April 2009 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 55 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: anaesthesia (general, regional); antibiotic regimens; arthroplasty; choice of implant for internal fixation; conservative treatment; co-ordinated multidisciplinary approaches for inpatient rehabilitation of older people; cyclical compression of the foot or calf; early supported discharge followed by home-based rehabilitation; extramedullary devices; fixation (external, internal); graduated elastic compression; intramedullary devices; mobilisation strategies; nerve blocks for pain control; nutritional supplementation (oral multinutrient feeds, nasogastric feeds); perioperative prophylaxis with antibiotics, with antiplatelet agents, or with heparin (low molecular weight or unfractionated); preoperative traction to the injured limb; and systematic multicomponent home-based rehabilitation.
This study investigates receptor activator NF-?B (RANK), RANK ligand (RANKL) and tumour necrosis factor (TNF?), key factors regulating bone turnover, present in the tissues near peri-prosthetic osteolysis. Tissue was obtained from zones of peri-prosthetic osteolysis from 11 patients undergoing revision of total hip prostheses, analysed preoperatively by high-resolution spiral multislice CT using a metal artefact suppression protocol. Synovial tissue from
Christopher A. Holding; David M. Findlay; Roumen Stamenkov; Susan D. Neale; Helen Lucas; A. S. S. K. Dharmapatni; Stuart A. Callary; Kush R. Shrestha; Gerald J. Atkins; Donald W. Howie; David R. Haynes
An effective lubrication can significantly reduce wear of metal-on-metal artificial hip joints. The improvement of the lubrication can be achieved through the optimisation of the bearing geometry in terms of a small clearance and\\/or the structural support such as a polyethylene backing underneath a metallic bearing in a sandwich acetabular cup form. The separate effects of these two factors on
Feng Liu; Zhongming Jin; Paul Roberts; Peter Grigoris
We have assessed the effect of different regimes of antibiotic prophylaxis on the survival of total hip implants, comparing antibiotics administered both systemically and in the bone cement, systemically only, in the bone cement only and with no antibiotics given. We studied 10 905 primary cemented total hip replacements, performed for osteoarthritis of the hip and reported to the Norwegian
B. Espehaug; L. B. Engesaeter; S. E. Vollset; L. I. Havelin; N. Langeland
Infectious prosthetic hip joint loosening: bacterial species involved in its aetiology and their antibiotic resistance profiles against antibiotics recommended for the therapy of implant-associated infections.
Reliable microbiological diagnosis along with surgery and prolonged antibiotic therapy are key elements in the management of prosthetic-joint infections (PJIs). The purpose of this study was to characterize antibiotic resistance profiles of bacteria involved in the aetiology of PJIs. A total of 33 bacterial isolates cultured from 31 patients undergoing exchange of total hip prostheses were analyzed. The diagnostic approach toward isolation of prosthesis- associated microorganisms included sonication of retrieved implants and conventional cultures of periprosthetic tissues and synovial fluid. The in vitro resistance profiles of bacterial isolates were determined in relation to antibiotics recommended for the therapy of PJIs using the disc diffusion method, E-tests(®) and broth microdilution system. Coagulase-negative staphylococci (CNS) were predominant microorganisms followed by Staphylococcus aureus, Enterobacter cloacae, Streptococcus mitis, and Propionibacterium acnes. Twenty out of 30 and 12 out of 30 staphylococcal isolates were methicillin- and multi-drug resistant, respectively. Only two isolates were rifampicinresistant. All staphylococci were susceptible to glycopeptides and linezolid. This paper stresses the pathogenic role of staphylococci in patients suffering from implant loosening and reports high methicillin- and multidrug-resistance rates in these bacteria. Hence, antimicrobial susceptibility tests of individual bacterial isolates must always be performed to guide selection of the optimal therapeutic option. PMID:24858648
Bogut, Agnieszka; Nied?wiadek, Justyna; Strzelec-Nowak, Dagmara; Blacha, Jan; Mazurkiewicz, Tomasz; Marczy?ski, Wojciech; Kozio?-Montewka, Maria
Preliminary Results of Implantation in Animal Model and Osteoblast Culture Evaluation of Prototypes of Biomimetic Multispiked Connecting Scaffold for Noncemented Stemless Resurfacing Hip Arthroplasty Endoprostheses
We present the new fixation method for RHA (resurfacing hip arthroplasty) endoprostheses by means of the biomimetic multispiked connecting scaffold (MSC-Scaffold). Such connecting scaffold can generate new type of RHA endoprostheses, that is stemless and fixed entirely without cement. The preprototypes of this MSC-Scaffold were manufactured with modern additive laser additive technology (SLM). The pilot surgical implantations in animal model (two laboratory swine) of MSC-Scaffold preprototypes have showed after two months neither implant loosening, migration, and nor other early complications. From the results of performed histopathological evaluation of the periscaffold spikes bone tissue and 10-day culture of human osteoblasts (NHOst) we can conclude that (1) the scaffolding effect was obtained and (2) to improve the osseointegration of the scaffold spikes, their material surface should be physicochemically modified (e.g., with hydroxyapatite). Some histopathological findings in the periscaffold domain near the MSC-Scaffold spikes bases (fibrous connective tissue and metallic particles near the MSC-Scaffold spikes bases edges) prompt considering the necessity to optimize the design of the MSC-Scaffold in the regions of its interspike space near the spikes bases edges, to provide more room for new bone formation in this region and for indispensable post-processing (glass pearl blasting) after the SLM manufacturing.
Uklejewski, Ryszard; Rogala, Piotr; Winiecki, Mariusz; Kedzia, Andrzej; Ruszkowski, Piotr
Total hip arthroplasty was originally indicated for older, sedentary patients because of concerns that catastrophic wear and failure would occur in younger and more active patients. With advances in implant design, tribology, and surgical technique, total hip arthroplasty has now become a viable option for younger patients seeking excellent pain relief and improvement in function. Long-term studies are needed to evaluate the outcome of hip arthroplasty in younger patients using the modern generation of implants and bearing surfaces. PMID:16958450
Sharkey, Peter F; Austin, Matthew S; Hozack, William
This paper explores the cost utility of metalon-metal hip resurfacing arthroplasty (MOM) as an alternative intervention to\\u000a total hip replacement or ‘watchful waiting’ for patients with advanced hip disease. Early implant failure among younger and\\u000a more active elderly patients can mean that the use of total hip replacement (THR) is delayed, with patients managed through\\u000a ‘watchful waiting’, a combination of
L. McKenzie; L. Vale; S. Stearns; K. McCormack
Bead shedding has been reported in both hip and knee arthroplasties and can result in increased polyethylene wear and metal ion release. The rates of bead loss were recorded for each device type, and the interfacial bead-substrate shear load to failure and contact areas of the beads were determined. The 3 components with the highest rate of bead loss, namely, S-Rom, Omnifit, and Optifix acetabular shells, recorded the lowest shear loads to failure. Percentage bead-substrate contact area ranged between 7% and 37% and was the most important factor affecting bead shedding. Other factors influencing bead loss in decreasing order of importance were bead fusion, bead size, component type (acetabular or knee), component loosening, and time in situ. PMID:22770858
Swarts, Eric; Kop, Alan M; Phillips, Michael
This study compared the accuracy and sensitivity of several numerical methods employing spherical or plane triangles for calculating the volumetric wear of retrieved metal-on-metal hip joint implants from coordinate measuring machine measurements. Five methods, one using spherical triangles and four using plane triangles to represent the bearing and the best-fit surfaces, were assessed and compared on a perfect hemisphere model and a hemi-ellipsoid model (i.e. unworn models), computer-generated wear models and wear-tested femoral balls, with point spacings of 0.5, 1, 2 and 3?mm. The results showed that the algorithm (Method 1) employing spherical triangles to represent the bearing surface and to scale the mesh to the best-fit surfaces produced adequate accuracy for the wear volume with point spacings of 0.5, 1, 2 and 3?mm. The algorithms (Methods 2-4) using plane triangles to represent the bearing surface and to scale the mesh to the best-fit surface also produced accuracies that were comparable to that with spherical triangles. In contrast, if the bearing surface was represented with a mesh of plane triangles and the best-fit surface was taken as a smooth surface without discretization (Method 5), the algorithm produced much lower accuracy with a point spacing of 0.5?mm than Methods 1-4 with a point spacing of 3?mm. PMID:24531891
Lu, Zhen; McKellop, Harry A
In a fuel assembly for a nuclear reactor a fuel element spacer formed of an array of laterally positioned cojoined tubular ferrules each providing a passage for one of the fuel elements, the elements being laterally supported in the ferrules between slender spring members and laterally oriented rigid stops.
Matzner, B.; Curulla, M. V.; Horn, V. M.; Price, J. F.
A nuclear fuel assembly is described containing cylindrical fuel rods having an outside radius and comprising: a top nozzle; a bottom nozzle; a control rod guide thimble extending between the top and bottom nozzles; fuel rod spacer grid assemblies axially disposed along the control rod guide thimble for maintaining the fuel rods in a space lateral array. Each of the
L. E. Weiland; B. H. Parks
This patent describes a spacer for restraining the fuel rods of a nuclear fuel assembly, the assembly being formed of a plurality of parallel, elongated fuel rods so arranged that the assembly is bounded by a polygon having an even number of sides, the rods being so arranged as to lie in a plurality of sets of parallel rows, the rows of each set being perpendicular to one of the sides of the polygon. It comprises a number of spacer combs equal to at least half the number of the sides of the polygon, the spacer combs being superposed on each other, each of the spacer combs comprising: a single base strip having a length equal to that of one of the sides of the polygon and grid strips equal in number to the spaces between rows in one of the sets, and at least a majority of the grid strips being of a length sufficient to extend substantially the full length of the rows; the grid strips being provided with spring members positioned to engage each of the rods; the grid strips being provided with spring members positioned to engage each of the rods; the grid strips being secured to and extending at right angles to the base strip; the grid strips of different combs being positioned at angles to each other, so as to occupy the spaces between rows in different sets.
Patterson, J.F.; Ewing, R.H.
A model has been developed for SCDAP to treat the effect of grid spacer removal. The model simply tests the grid temperature against the melting temperature of the grid spacer material. If the grid spacer temperature is equal to or above its melting tempe...
G. A. Berna
Objective To estimate the risk of death or severe harm due to bone cement implantation syndrome (BCIS) among patients undergoing hip hemiarthroplasty for fractured neck of femur. Setting Hospitals providing secondary and tertiary care throughout the National Health Service (NHS) in England and Wales. Participants Cases reported to the National Reporting and Learning System (NRLS) in which the reporter clearly describes severe acute patient deterioration associated with cement use in hip hemiarthroplasty for fractured neck of femur (assessed independently by two reviewers). Outcome measures Primary—number of reported deaths, cardiac arrests and periarrests per year. Secondary—timing of deterioration and outcome in relation to cement insertion. Results Between 2005 and 2012, the NRLS received 62 reports that clearly describe death or severe harm associated with the use of cement in hip hemiarthroplasty for fractured neck of femur. There was one such incident for every 2900 hemiarthroplasties for fractured neck of femur during the period. Of the 62 reports, 41 patients died, 14 were resuscitated from cardiac arrest and 7 from periarrest. Most reports (55/62, 89%) describe acute deterioration occurring during or within a few minutes of cement insertion. The vast majority of deaths (33/41, 80%) occurred on the operating table. Conclusions These reports provide narrative evidence from England and Wales that cement use in hip hemiarthroplasty for fractured neck of femur is associated with instances of perioperative death or severe harm consistent with BCIS. In 2009, the National Patient Safety Agency publicised this issue and encouraged the use of mitigation measures. Three-quarters of the deaths in this study have occurred since that alert, suggesting incomplete implementation or effectiveness of those mitigation measures. There is a need for stronger evidence that weighs the risks and benefits of cement in hip hemiarthroplasty for fractured neck of femur.
Rutter, Paul D; Panesar, Sukhmeet S; Darzi, Ara; Donaldson, Liam J
Hip resurfacing is an attractive concept because it preserves rather than removes the femoral head and neck. Most early designs\\u000a had high failure rates, but one unique design had a femoral stem. Because that particular device appeared to have better implant\\u000a survival, this study assessed the clinical outcome and long-term survivorship of a hip resurfacing prosthesis. Four hundred\\u000a forty-five patients
James W. Pritchett
The authors present analysis of dislocation following hip arthroplasty based on their own clinical material of 1985-2005 year. It contain 2712 cases of total hip arthroplasty, 2171 (80.1%) cases were cemented including 64 (2.4%) cases of revised arthroplasty, 541 (19.9%) cases were cement-free stabilized including 7 (0.2%) cases of revised arthroplasty. Obtained outcomes of analysis permit to make assertion that dislocation following hip arthroplasty occurred during first three month after surgery, more frequently in case of revised arthroplasty and following fractures of femoral neck. Requirement of success is appropriate steady of implant and right done supervision of rehabilitation with learned necessary motoric behaviors. PMID:17131724
Golec, Edward; Nowak, Sebastian; Golec, Joanna; Abrowski, Janusz; Jasiak-Tyrkalska, Bozena
A finite element analysis (FEA) was performed on six hip stem designs. The hip implant designs were then analyzed at forces ranging from 2.5 to 7kN. These forces were selected because a typical gait cycle generates forces up to 6–7 times the body weight in the hip joint. The FEA results were compared for various stem designs assuming a rectangular
David Bennett; Tarun Goswami
Introduction Single surgeon studies from specialized centers have suggested that metal-on-metal hip resurfacing in patients with osteonecrosis\\u000a of hip joint provides good implant survival and function.\\u000a \\u000a \\u000a \\u000a \\u000a Method We tested the hypothesis that multicenter results of hip resurfacing, in terms of function and survival, are similar between\\u000a patients with osteoarthritis and osteonecrosis.\\u000a \\u000a \\u000a \\u000a \\u000a Patients 192 patients (202 hips) underwent metal-on-metal hip resurfacing at different centers
Tajeshwar S. Aulakh; Chandra Rao; Jan-Herman Kuiper; James B. Richardson
Current outcomes data on revision total hip arthroplasty focuses on specific implants and techniques rather than more general outcomes. We therefore examined a large consecutive series of failed THAs undergoing revision to determine if survivorship and modes of failure differ in comparison to the current data. We retrospectively reviewed the medical records of 1100 revision THAs. The minimum followup was 2 years (mean, 6 years; range, 0–20.4 years). Eighty-seven percent of revision total hips required no further surgery; however, 141 hips (13%) underwent a second revision at a mean of 3.7 years (range, 0.025–15.9 years). Seventy percent (98 hips) had a second revision for a diagnosis different from that of their index revision, while 30% (43 hips) had a second revision for the same diagnosis. The most common reasons for failure were instability (49 of 141 hips, 35%), aseptic loosening (42 of 141 hips, 30%), osteolysis and/or wear (17 of 141 hips, 12%), infection (17 of 141 hips, 12%), miscellaneous (13 of 141 hips, 9%), and periprosthetic fracture (three of 141 hips, 2%). Survivorship for revision total hip arthroplasty using second revision as endpoint was 82% at 10 years. Aseptic loosening and instability accounted for 65% of these failures. Level of Evidence: Level IV, therapeutic (retrospective) study. See the Guidelines for Authors for a complete description of levels of evidence.
Fehring, Thomas K.; Griffin, William L.; Odum, Susan M.; Masonis, John L.
A typical embodiment of the invention provides structural support for the grids in a nuclear reactor fuel assembly. Illustratively, the external surfaces of water rods or instrument tubes in a fuel assembly are provided with annular recesses. A spacer grid retainer is engaged within the recesses by means of spring loaded fingers on the retainer, in which the spring loading forces are greater than anticipated vibration forces to reduce fretting corrosion. Notches formed in the retainer secure the grid to the retainer, all in a manner that simplifies fuel assembly construction and restricts grid movement at lower cost.
A nuclear reactor fuel assembly spacer grid. The grid straps form an egg crate configuration creating standard cells to enclose the fuel rods. The standard cells have at least one of their straps with an integral spring portion extending into the standard cell and pushing against the fuel rod. A distinct backup spring is positioned transverse to and behind each of the spring portions of the straps and is positioned so as not to touch the fuel rods. The straps are made of a material having a low neutron capture cross-section while the backup spring is made of a material having good radiation stress relaxation properties.
Hellman, J. M.; DeMario, E. E.
The use of an elevated-rim acetabular liner in total hip arthroplasty (THA) is widely accepted. We sought to determine quantitatively the amount of additional stability provided by the elevated-rim liner as compared to the standard non-elevated liner. Furthermore, the stability of the hip with a 32-mm femoral head was compared to the standard 28-mm head. Our results show that a
P. G. SULTAN; V. TAN; M. LAI; J. P. GARINO
A nuclear fuel assembly is described containing cylindrical fuel rods having an outside radius and comprising: a top nozzle; a bottom nozzle; a control rod guide thimble extending between the top and bottom nozzles; fuel rod spacer grid assemblies axially disposed along the control rod guide thimble for maintaining the fuel rods in a space lateral array. Each of the spacer grid assemblies comprises grid straps interlocked into an egg-crate configuration to form cells through which the fuel rods pass. Each of the cells has a grid spring and an opposing dimple. Each of the grid spring and dimple has an arcuate surface portion contoured to conform, in both the axial and radial directions, to the surface of the generally cylindrical fuel rods and adapted to contact the fuel rods along at least a line of contact as the fuel rods pass through the cells. The arcuate portions have radius of curvature equal to or greater than the outside radius of the fuel rods.
Weiland, L.E.; Parks, B.H.
A system for capturing a grid spacer in a nuclear fuel bundle which comprises a split sleeve fixed to a capture rod is described. The sleeve is used in conjunction with a grid spacer having openings formed by intersecting walls which include protrusions and coacting springs extending from the walls. The sleeve includes pairs of longitudinally spaced bosses and a
B. S. Flora; J. F. Patterson
A nuclear fuel assembly containing generally cylindrical fuel rods, is described comprising: a top nozzle; a bottom nozzle, a control rod guide thimble extending between the top and bottom nozzles; fuel rod spacer grid assemblies axially disposed along the control rod guide thimble for maintaining the fuel rods in a spaced lateral array. Each of the spacer grid assemblies comprises
H. M. Ferrari; E. Roberts; E. E. De Mario
Uncemented hip replacement matches the best results of classic cemented replacements. With the aim of preserving bone and soft tissue, implants with shorter stems and proximal metaphyseal support have been developed. Likewise, the lack of distal load should avoid cortical diaphyseal remodelling phenomena and the thigh pain of some cylindrical and wedge implants. The resurfacing implant, very popular as a conservative hip replacement in the young adult, has disadvantages associated with the fragility of the neck and with large head metal friction torque. Short stem hip replacement may be a reasonable alternative to classic implants and surface hip replacements. The different designs of conservative short stem implants are analysed, and are classified according to their morphology and biomechanical characteristics. Some medium term series show promising results. PMID:23177948
Valverde-Mordt, C; Valverde-Belda, D
Thirty-one snapping hips in 24 patients were followed for 4 (1-11) years after operation. At follow-up, snapping persisted in nine hips, in three cases accompanied by pain. The femoral neck angle was less in the patients (128 degrees) than in a control group (134 degrees). PMID:3705944
Larsen, E; Johansen, J
The ABG I uncemented hip prosthesis has demonstrated an unacceptably high failure rate and poor functional outcome in our patients. A prospective review was performed of 38 implanted hips with a mean follow-up of 11 years. Sixteen hips have been revised or are candidates for revision hip surgery, due principally to polyethylene wear and pelvic osteolysis. Contributing factors were likely to be the poor wear characteristics of the polyethylene liners—which were gamma irradiated in air—and the thinness of these liners. Of further concern were the poor pain and function scores in the remaining hips [mean Harris Hip Scores (HHS) of 70 (SD 22) at 11-year follow-up]. The influence of the surgical learning curve on clinical results may have been an important factor. Undersized femoral components were associated with poor pain and functional scores in five patients with HHS < 60. All ABG I hip implants must remain under careful, long-term review.
Muddu, B. N.
The ABG I uncemented hip prosthesis has demonstrated an unacceptably high failure rate and poor functional outcome in our patients. A prospective review was performed of 38 implanted hips with a mean follow-up of 11 years. Sixteen hips have been revised or are candidates for revision hip surgery, due principally to polyethylene wear and pelvic osteolysis. Contributing factors were likely to be the poor wear characteristics of the polyethylene liners--which were gamma irradiated in air--and the thinness of these liners. Of further concern were the poor pain and function scores in the remaining hips [mean Harris Hip Scores (HHS) of 70 (SD 22) at 11-year follow-up]. The influence of the surgical learning curve on clinical results may have been an important factor. Undersized femoral components were associated with poor pain and functional scores in five patients with HHS < 60. All ABG I hip implants must remain under careful, long-term review. PMID:16521011
Kim, W Y; Muddu, B N
Summary Painful hip prosthesis is the most feared immediate and remote complication of a primary implant and usually represents the failure of one or more therapeutic moments. In cases of aseptic implant failure, the causes invoked may be represented by an incorrect indication, the quality of materials, local and general condition of the patient and especially from a bad joint biomechanics. In cases of septic loosening, however, the cause of failure to be found in the location of pathogens within the implant. In planning a revision is necessary to respect many important steps. They are represented by the exact identification of the causes of failure, the correct preoperative planning, by respecting the skin incisions, the proper choice of the prosthesis, planning the surgical technique, and finally by an appropriate rehabilitation program. In the evaluation of hip failure the first diagnostic step is to recognize exactly those aseptic and septic forms anyway to exclude the diagnosis of infection.
Spinarelli, Antonio; Patella, Vittorio; Conserva, Vito; Vicenti, Giovanni; Pesce, Vito; Patella, Silvio
50 years ago, prosthetic replacement of the hip joint ushered in a new epoch in orthopaedics. Total hip replacement made it possible to remove a severely diseased, painful hip and restore normal function and a normal quality of life to the afflicted patient. The early results of total hip replacement are almost all spectacular and hip replacement has become the most successful type of orthopaedic surgery. These good results using an approach that was technically relatively simple resulted in a temptation to implant prosthetic hip joints with ever increasing frequency in ever younger patients. This led to the emergence of new problems, which were not so clearly recognised at the outset: it emerged that the stability of prosthetic hip joints was of limited duration. This had the following consequence: If a total hip prosthesis is implanted in an elderly person whose remaining life-expectancy is shorter than the longevity of the prosthesis, hip replacement is a life-long solution. We can therefore say that, for a patient who has only 10 to 15 years left to live, their hip problem is solved by total hip replacement. For young people, who still have a long life expectancy in front of them, it is different. They will experience failure of the artificial joint and require further surgery. The commonest and most important type of failure in total hip prostheses is aseptic loosening, which is associated with resorption of bone at the site of the prosthesis. The cause of this phenomenon has only gradually been recognised in the course of the years. Initially, the unanimous opinion was that the methacrylate cement, used to fix the components of the prosthesis in the bone, was the definitive cause of aseptic loosening because fissures and fractures of the cement were almost always found during surgical revision of loosened joints. There was talk of "cement disease" and great efforts were made to improve the quality of the cement and the cementing technique. Moreover, even today, there is no established answer to the question whether, over the course of many years, cement ages and becomes friable, a process that may have major implications for young patients. For this reason, ways of reliably fixing the prosthesis in the bone without methacrylate cement were also explored at the same time. Valuable pioneering work in this field was carried out with uncemented dental implants made of titanium and with a roughened surface. With these implants, the phenomenon of osseointegration, i.e. the deposition of bone directly on the roughened metal surface without any intervening connective tissue, was observed. This phenomenon has also been utilised successfully in hip prostheses: if artificial hips made of titanium alloy with a coarse-blasted surface and with a high primary mechanical stability are placed in the bone, osseointegration also occurs. In parallel with this development, Willert, from Göttingen, identified the most important cause of loosening of the prosthesis: he established that, when an artificial joint articulates, very fine particles of polyethylene are eroded from the prosthetic cup when the surfaces of the joint glide over one another and that these are only partially removed by the lymphatic system. A large proportion of the particles accumulates in the artificial joint and in the gap between the prosthesis and the bone, giving rise to foreign body granulomata, which resorb bone thus leading to loosening. The number of eroded particles is considerable. In 1998, Patricia Campbell, from Los Angeles, showed that 470,000 particles per step were produced from an articulation between a metal head and a polyethylene cup. This huge number gives an indication how small these particles are, since the linear erosion of the polyethylene surface only amounts to about 0.1 to 0.2 mm a year. This relatively recent recognition of "particle disease" has led to the investigation of other materials, which produce fewer erosion particles, for artificial joint articulations. Three possible options are available today, but it
Wagner, H; Wagner, M
Definitive radiotherapy is a well-recognized treatment option for localized prostate cancer. Rectum toxicity is the dose-limiting toxicity. Dose-volume correlations have been reported in many studies. The application of a spacer to increase the distance between the prostate and anterior rectal wall is an innovative technique, considerably reducing the dose to the rectum. Hyaluronic acid, human collagen, an inflatable balloon or hydrogel are potential materials to create the desired effect. The number of clinical studies is rapidly increasing. Well-tolerated injection or implantation techniques and low rectal treatment-related toxicity have been demonstrated in prospective studies. Long-term clinical results and the results of randomized studies are needed to better define the beneficial effect for the patient. PMID:24799065
In newborns, US has an established role in the detection and management of developmental dysplasia of the hip. Later in childhood, when the limping child is a major diagnostic dilemma, US is extremely helpful in the identification of the varied disease processes underlying this condition, as transient synovitis, septic arthritis, Perthes disease and slipped femoral capital epiphysis. In adolescent practicing sporting activities, US is an excellent means to identify apophyseal injures about the pelvic ring, especially when avulsions are undisplaced and difficult-to-see radiographically. Later on, in the adulthood, US is an effective modality to diagnose tendon and muscle injuries about the hip and pelvis, identify effusion or synovitis within the hip joint or its adjacent bursae and guide the treatment of these findings. The aim of this article is to provide a comprehensive review of the most common pathologic conditions about the hip, in which the contribution of US is relevant for the diagnostic work-up. PMID:21571471
Martinoli, Carlo; Garello, Isabella; Marchetti, Alessandra; Palmieri, Federigo; Altafini, Luisa; Valle, Maura; Tagliafico, Alberto
In summary, implants are highly successful because encapsulation occurs around the implant without rejection and no other fixation is necessary. There is relatively no shortening or instability of the toe, such as a floppy toe. This seems to prevent painful stiff pseudoarthrosis or arthritis because it acts as a spacer to prevent narrowing of the joint and allows for movement. It prevents a short first toe and prevents any undesired cosmetic results, as it provides the joint with a pain-free range of motion, allowing it to become more mobile and stable. Also, ulnar implants have been used with the same indications and contraindications. The most important consideration about implant surgery is that these implants, that is, the Silastic and the Swanson design, are nonabsorbable. They will not cause tissue reaction and the fibrous encapsulation forms all that is necessary to encapsulate the implant itself; therefore, there is very little bony rejection. From recent literature and through professional experience, it has been proved that implants act primarily as a spacer. They provide a pain-free range of motion but not as well as desired. Implants provide stability to the joint, which is of the utmost importance. The Silastic implants have stood the test of time in most cases. However, the search for better biomaterials, better results, and better functions is never ending. There is a great need for continued research into this field. Podiatry must continue to maintain, contribute, and improve this research. PMID:6399227
Kaplan, E G; Kaplan, G S; Kaplan, D M; Kaplan, R K
Hip resurfacing devices require a new radiographic evaluation technique owing to femoral components with short or no stems. Fourteen US surgeons implanted 1148 metal-on-metal hip resurfacing (HR) devices in a US-FDA-IDE clinical trial, which began in 2001. In this multi-center, prospective study, 337 patients (mean age, 50.1 years) were enrolled as a study group of unilateral HR arthroplasties. Radiographs of
Rama Ramakrishnan; William L. Jaffe; William R. Kennedy
A weld fixture for receiving and aligning the fuel rod contact points of a nuclear fuel bundle spacer grid is disclosed. Two plates are provided with intersecting unequally spaced slots that define polygons on one side of each plate. Both plates have bores therethrough substantially at the slot intersections and in the slots adjacent the outer edges of the plates. Bores are provided through both plates in polygons that correspond to fuel assembly guide tube and instrument tube locations. These positions receive guide cell pins during use, some of which are hollow and are used to bolt the plates together over the spacer grid strips. Bores in each plate through the defined polygons receive alignment pins. Guide rods receive and align the plates through corner bores in each plate. The slots and pins in the facing plates align the critical fuel rod contact points in the spacer grid during the intersection welding process. 19 figs.
Johnson, G. Jr.; King, R.A.; Minnick, E.C. III
The optimal implant option for hip arthroplasty in the young, active patient remains controversial. There has been renewed interest for metal-on-metal hip resurfacing due to improved design and manufacturing of implants, better materials, enhanced implant fixation, theoretical advantages over conventional total hip arthroplasty, and recent Food and Drug Administration approval of two devices. Recent studies indicate satisfactory short- and midterm clinical results (1- to 10-year followup) with low complication rates, but there is a learning curve associated with this procedure, a more extensive surgical approach is necessary, and long-term results have yet to be determined. Proper patient selection may help avoid complications and improve patient outcomes. Patient selection criteria in the literature appear based predominantly on theoretical considerations without any consensus on stratifying patient risk. The most commonly reported complications encountered with hip resurfacing include femoral neck fracture, acetabular component loosening, metal hypersensitivity, dislocation, and nerve injury. At the time of clinical evaluation, patient age; gender; diagnosis; bone density, quality, and morphology; activity level; leg lengths; renal function; and metal hypersensitivity are important factors when considering a patient for hip resurfacing. Based on our review, we believe the best candidates for hip resurfacing are men under age 65 with osteoarthritis and relatively normal bony morphology. Level of Evidence: Level V, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18941859
Nunley, Ryan M; Della Valle, Craig J; Barrack, Robert L
Introduction The standard treatment for patients who require total hip replacement is the implantation of an intramedullary diaphyseal anchored hip prosthesis. A bone-sparing thrust plate hip prosthesis (TPP) can be used as an alternative device for young patients. The TPP relies on proximal femoral metaphyseal fixation. The theoretical advantage of leaving diaphyseal bone intact is easier conversion to a stemmed
Boris A. Zelle; Torsten G. Gerich; Leonard Bastian; Franklin D. Shuler; Hans-Christoph Pape; Christian Krettek
The results of a consecutive series of uncemented total hip arthroplasties in patients 50 years or younger are reviewed. There were 41 total hip arthroplasties in 36 patients at an average follow-up period of 5.3 years. Average patient age was 42 years at the time of implantation. Preoperative Harris hip score (HHS) averaged 39100; the final HHS averaged 93. Radiographic
Paul A. Dowdy; Cecil H. Rorabeck; Robert B. Bourne
Hip replacement surgeries are on the rise in India. However, for these surgeries, most of the implants used are imported and manufactured entirely to suit the geometrical considerations of the western population. Studies in the past have shown that there are anatomical variations in the hip joint for different ethnic backgrounds and geographical locations. There is paucity of anthropometric hip
Vaibhav Bagaria; Shirish Deshpande; Abhay Kuthe; Darshana D. Rasalkar; Bhawan K. Paunipagar; Tanushree Subhash Madhugiri
This prospective study examined patient characteristics and radiographic findings for 89 subjects undergoing total hip resurfacing. Thirteen (14.6%) of 89 hips have required revision. Female sex, smaller implant size, and diagnosis of osteonecrosis were associated with lower device survival. No significant differences in acetabular cup angle and stem angle were observed between revised and nonrevised hips. Revision rates for the
Lucas S. Rylander; Joseph C. Milbrandt; Adam B. Wallace; D. Gordon Allan
A weld fixture for receiving and aligning the fuel rod contact points of a nuclear fuel bundle spacer grid is disclosed. Two plates are provided with intersecting unequally spaced slots that define polygons on one side of each plate. Both plates have bores therethrough substantially at the slot intersections and in the slots adjacent the outer edges of the plates.
G. Jr. Johnson; R. A. King; E. C. Minnick
The 20-year performance of metal-on-metal hip articulations has not been reported. Five McKee—Farrar total hip prostheses and one Sivash prosthesis were obtained at revision surgery after a mean implantation time of 21.3 years. A radiographic, histologic, implant, and wear analysis was performed on these total hip implants with cobalt—chrome metal-on-metal articulations. All cases were associated with femoral component loosening, but
Thomas P. Schmalzried; Paul C. Peters; Brian T. Maurer; Charles R. Bragdon; William H. Harris
A poll was conducted at the 2009 Annual Meeting of the American Association of Hip and Knee Surgeons to determine current practices among its members in primary total hip arthroplasty and total knee arthroplasty. This article summarizes the audience responses to a number of multiple choice questions concerning perioperative management and operative practice patterns and preferences including anesthetic choices, blood management, surgical approaches, implant selection, implant fixation, bearing surface choice, postoperative rehabilitation, recommended postoperative activity restrictions, and antibiotic prophylaxis. PMID:20580196
Berry, Daniel J; Bozic, Kevin J
Hip hemiarthroplasty (HHA) and total hip arthroplasty (THA) infections are usually considered as one entity; however, they may show important differences. We analyze these differences, as well as predictors of treatment failure (TF) and poor functional status among patients with prosthetic hip infections (PHIs). A multicenter cohort study of consecutive patients with PHIs was performed. The main outcome variable was TF after the first surgical treatment performed to treat the infection. Multivariate analysis was used to identify predictors of TF. A total of 127 patients with PHI were included (43 HHA, 84 THA). Patients with HHA infections were more frequently women (88 % vs. 54 %; p?0.001), had comorbidities (86 % vs. 67 %, p?=?0.02), and were older (median age 79 vs. 65 years, p?0.001), and the reason for arthroplasty was more frequently a fracture (100 % vs. 18 %, p?0.001). Failure of initial treatment and crude mortality were more frequent among HHA patients (44 % vs. 23 %, p?=?0.01 and 28 % vs. 7 %, p?=?0.001, respectively). However, HHA was not associated with TF in the multivariate analysis when hip fracture was considered; thus, variables independently associated with TF were hip fracture, inadequate surgical management, prosthesis retention, and higher C-reactive protein level. Failure of the first surgical treatment was associated with poorer functional status. HHA and THA infections showed significant differences in epidemiology, clinical features, and outcome. Although patients with HHA infections had a higher risk of TF, this was related to the reason for hip implant: a hip fracture. Success of the initial management of infection is a predictor of better clinical and functional outcome. PMID:24671411
Del Toro, M D; Nieto, I; Guerrero, F; Corzo, J; Del Arco, A; Palomino, J; Nuño, E; Lomas, J M; Natera, C; Fajardo, J M; Delgado, J; Torres-Tortosa, M; Romero, A; Martín-Rico, P; Muniain, M A; Rodríguez-Baño, J
A spacer grid assembly is disclosed for retaining a plurality of fuel rods in substantially parallel spaced relation, the spacer grids being formed with rhombic openings defining contact means for engaging from one to four fuel rods arranged in each opening, the spacer grids being of symmetric configuration with their rhombic openings being asymmetrically offset to permit inversion and relative
Snyder Jr. Harold J; Anthony R. Veca; Harry A. Donck
A model has been developed for SCDAP to treat the effect of grid spacer removal. The model simply tests the grid temperature against the melting temperature of the grid spacer material. If the grid spacer temperature is equal to or above its melting temperature, the grid is removed as an obstruction.
Hip fractures are ranked among the frequent injuries. These fractures have been often coupled with high energy trauma in children and in patients with normal bone structure, low energy trauma and osteoporotic fracture (fragility fracture) is typical in elder patients. Hip fractures are divided into five groups: femoral head fracture, femoral neck fracture, pertrochanteric, intertrochateric and subtrochanteric fracture. Surgical treatment is indicated in all patients unless contraindications are present. Long bed rest has been accompanied by a high risk of development of thromboembolic disease, pneumonia and bed sore. Healing in the wrong position and nonunions are often the result of conservative treatment. Screw osteosynthesis is performed in isolated femoral head factures. Three cannulated screws or a DHS plate (dynamic hip screw) are used in fractures of the femoral neck with normal femoral head perfusion, total hip replacement is recommended in elder patients and in case of loss of blood supply of the femoral head. Pertrochanteric and intertrochanteric fractures can be stabilized by the femoral nails (PFN, PFN A, PFH - proximal femoral nail), nails are suitable for minimally invasive insertion and provide higher stability in the shaft, or plates (DHS) designed for stable pertronchanteric and intertrochanteric fractures. Subtrochanteric fractures can be fixed also intramedullary (nails - PFN long, PFN A long) and extramedullary (plates - DCS dynamic condylar screw, proximal femoral LCP - locking compression plate). Open reduction with internal plate fixation is advantageous for pathological fractures, as biopsy sampling can be performed. Hip fracture rehabilitation is integral part of the treatment, including walking on crutches or with a walker with partial weight bearing for at least six weeks. PMID:24131459
Weisová, Drahomíra; Salášek, Martin; Pavelka, Tomáš
Diamond has many superior, desired characteristics of implant materials such as low friction, high wear and corrosion resistance, and well bonding surface to bone. The potential of diamond for total hip replacement implants was studied in the form of amorphous diamond coatings on conventional metal implant materials. Amorphous diamond coatings (sp3 bonding fraction 80%, thickness 0.2 to 10 microns) were deposited on stainless steel AISI316L, Ti6A14V, and CoCrMo alloys using filtered pulsed plasma are discharge method. Superior attachment of coatings to the implant materials was achieved by using high energy plasma beams to deposit amorphous diamond and proper intermediate layers. Previously it was shown that these coatings are biocompatible causing no local tissue reactions. Tribologic studies using a pin on disk apparatus with coated or uncoated implant materials in 1 wt.% NaCl distilled water were performed. A simplified hip joint simulator was used for preliminary testing of metal on polyethylene and metal on metal artificial hip joints modified with amorphous diamond coating. The average coefficients of friction were typically in the range of 0.03 to 0.11 for amorphous diamond coated materials. In the case of metal on metal hip implants, the average friction during initial running in period was improved (coefficient of friction = 0.07) compared with the same metal on metal pair (coefficient of friction = 0.22) and sliding was significantly smoother. In pin on disk wear tests, the average wear factors obtained were 140.10(-6), 5.0.10(-6), and < 0.1.10(-6) mm3/Nm for the pairs of AISI316L, CoCrMo, and the same materials with amorphous diamond coating. The corrosion rates of these implant materials in 10 wt.% HCl solution were decreased by a factor of 10,000 to 15,000 and any damage of the coatings was not observed in 6 months. The results of the tests show that in all the combinations studied, amorphous diamond coating improved definitely the wear and corrosion resistance compared with the uncoated materials. PMID:9678039
Lappalainen, R; Anttila, A; Heinonen, H
Periprosthetic infection after total knee arthroplasty is a devastating complication, and two-stage exchange is the standard of care in North America. Articulating and static spacers have been developed to treat these infections but controversy exists over which method is superior. We performed a systematic review using MEDLINE and other literature search engines identifying 47 articles meeting inclusion criteria producing 2011 spacers for comparison. Articulating spacers had increased range of motion 100.1° vs. 82.9° (P<0.003), lower re-infection rate 7.5% (P<0.0031), facilitated re-implantation (P<0.0011), and developed less bone loss (P<.0001) than did static spacers. This study answers several clinically relevant questions and provides useful information in guiding clinical decision making in treating periprosthetic infection. PMID:24268975
Guild, George N; Wu, Baohua; Scuderi, Giles R
We prospectively evaluated the accuracy of digital compared to analogue pre-operative templating in 50 consecutive primary\\u000a hip replacements between April 2006 and June 2007. The senior author pre-operatively templated implant size using TraumaCad\\u000a (Orthocrat Limited, Israel). Thirty-one Exeter primary hip and 19 hybrid hip replacements were performed. Hips were templated\\u000a using radiographs calibrated against a spherical metal ball. For each
M. Hossain; J. Lewis; A. Sinha
Background The renewed popularity of resurfacing hip arthroplasty in the last 10 years has generated a remarkable quantity of scientific contributions based on mid- and short-term follow-up. More than one paper has reported a consistent early revision rate as a consequence of biological or biomechanical failure. Two major complications are commonly described with resurfacing implants: avascular necrosis and femoral-neck fracture. A close relationship between these two events has been suggested, but not firmly demonstrated, whereas cementing technique seems to be better understood as potential cause of failure. Methods We performed an in vitro study in which four different resurfacing implants were evaluated with a simulated femoral head, two types of cement, (low and high viscosity) and two cementing techniques: direct (cement apposition directly on the femoral head) and indirect (cement poured into the femoral component). Results High-viscosity cement showed homogeneous distribution over the entire femoral head. Low-viscosity cement showed a massive polar concentration with insufficient, if not absent, distribution in the equatorial zone. Conclusion Polar cement concentration could be a risk factor for early implant failure due to two effects on the femoral head: biological (excessive local exothermic reaction could cause osteocyte necrosis) and biomechanical (which could lead to uneven load distribution on the femoral head).
Favetti, Fabio; Casella, Filippo; Papalia, Matteo; Panegrossi, Gabriele
Generator stator cores are constructed by stacking many layers of magnetic laminations. Ventilation ducts may be inserted between these layers by inserting spacers into the core stack. The ventilation ducts allow for the passage of cooling gas through the core during operation. The spacers or spacer posts are positioned between groups of the magnetic laminations to define the ventilation ducts. The spacer posts are secured with longitudinal axes thereof substantially parallel to the core axis. With this structure, core tightness can be assured while maximizing ventilation duct cross section for gas flow and minimizing magnetic loss in the spacers.
Griffith, John Wesley (Schenectady, NY); Tong, Wei (Clifton Park, NY)
A spacer grid assembly is disclosed for retaining a plurality of fuel rods in substantially parallel spaced relation, the spacer grids being formed with rhombic openings defining contact means for engaging from one to four fuel rods arranged in each opening, the spacer grids being of symmetric configuration with their rhombic openings being asymmetrically offset to permit inversion and relative rotation of the similar spacer grids for improved support of the fuel rods. An improved locking mechanism includes tie bars having chordal surfaces to facilitate their installation in slotted circular openings of the spacer grids, the tie rods being rotatable into locking engagement with the slotted openings.
Donck, H.A.; Snyder, H.J.; Veca, A.R.
A spacer grid assembly is disclosed for retaining a plurality of fuel rods in substantially parallel spaced relation, the spacer grids being formed with rhombic openings defining contact means for engaging from one to four fuel rods arranged in each opening. The spacer grids are of symmetric configuration with their rhombic openings being asymmetrically offset to permit inversion and relative rotation of the similar spacer grids for improved support of the fuel rods. An improved locking mechanism includes tie bars having chordal surfaces to facilitate their installation in slotted circular openings of the spacer grids, the tie rods being rotatable into locking engagement with the slotted openings.
A spacer grid assembly is disclosed for retaining a plurality of fuel rods in substantially parallel spaced relation, the spacer grids being formed with rhombic openings defining contact means for engaging from one to four fuel rods arranged in each opening, the spacer grids being of symmetric configuration with their rhombic openings being asymmetrically offset to permit inversion and relative rotation of the similar spacer grids for improved support of the fuel rods. An improved locking mechanism includes tie bars having chordal surfaces to facilitate their installation in slotted circular openings of the spacer grids, the tie rods being rotatable into locking engagement with the slotted openings.
Snyder, Jr., Harold J. (Rancho Santa Fe, CA); Veca, Anthony R. (San Diego, CA); Donck, Harry A. (San Diego, CA)
A nuclear fuel assembly containing generally cylindrical fuel rods, is described comprising: a top nozzle; a bottom nozzle, a control rod guide thimble extending between the top and bottom nozzles; fuel rod spacer grid assemblies axially disposed along the control rod guide thimble for maintaining the fuel rods in a spaced lateral array. Each of the spacer grid assemblies comprises grid straps interlocked into an egg-crate configuration to form cells through which the fuel rods pass. Each of the cells has a grid spring and at least one opposing dimple. Each grid spring and opposing dimple has a first selected spring force for a lowermost grid, a second selected spring force for an intermediate grid, and a third selected spring force for an uppermost grid less than the first and second spring forces. The first, second and third spring forces allow the fuel rods to expand in their respective cells.
Ferrari, H.M.; Roberts, E.; De Mario, E.E.
Executive Summary Objective The objective of this review was to assess the safety and effectiveness of metal on metal (MOM) hip resurfacing arthroplasty for young patients compared with that of total hip replacement (THR) in the same population. Clinical Need Total hip replacement has proved to be very effective for late middle-aged and elderly patients with severe degenerative diseases of the hips. As indications for THR began to include younger patients and those with a more active life style, the longevity of the implant became a concern. Evidence suggests that these patients experience relatively higher rates of early implant failure and the need for revision. The Swedish hip registry, for example, has demonstrated a survival rate in excess of 80% at 20 years for those aged over 65 years, whereas this figure was 33% by 16 years in those aged under 55 years. Hip resurfacing arthroplasty is a bone-conserving alternative to THR that restores normal joint biomechanics and load transfer. The technique has been used around the world for more than 10 years, specifically in the United Kingdom and other European countries. The Technology Metal-on-metal hip resurfacing arthroplasty is an alternative procedure to conventional THR in younger patients. Hip resurfacing arthroplasty is less invasive than THR and addresses the problem of preserving femoral bone stock at the initial operation. This means that future hip revisions are possible with THR if the initial MOM arthroplasty becomes less effective with time in these younger patients. The procedure involves the removal and replacement of the surface of the femoral head with a hollow metal hemisphere, which fits into a metal acetabular cup. Hip resurfacing arthroplasty is a technically more demanding procedure than is conventional THR. In hip resurfacing, the femoral head is retained, which makes it much more difficult to access the acetabular cup. However, hip resurfacing arthroplasty has several advantages over a conventional THR with a small (28 mm) ball. First, the large femoral head reduces the chance of dislocation, so that rates of dislocation are less than those with conventional THR. Second, the range of motion with hip resurfacing arthroplasty is higher than that achieved with conventional THR. A variety of MOM hip resurfacing implants are used in clinical practice. Six MOM hip resurfacing implants have been issued licences in Canada. Review Strategy A search of electronic bibliographies (OVID Medline, Medline In-Process and Other Non-Indexed Citations, Embase, Cochrane CENTRAL and DSR, INAHTA) was undertaken to identify evidence published from Jan 1, 1997 to October 27, 2005. The search was limited to English-language articles and human studies. The literature search yielded 245 citations. Of these, 11 met inclusion criteria (9 for effectiveness, 2 for safety). The result of the only reported randomized controlled trial on MOM hip resurfacing arthroplasty could not be included in this assessment, because it used a cemented acetabular component, whereas in the new generation of implants, a cementless acetabular component is used. After omitting this publication, only case series remained. Summary of Findings Health Outcomes The Harris hip score and SF-12 are 2 measures commonly used to report health outcomes in MOM hip resurfacing arthroplasty studies. Other scales used are the Oxford hip score and the University of California Los Angeles hip score. The case series showed that the mean revision rate of MOM hip resurfacing arthroplasty is 1.5% and the incidence of femoral neck fracture is 0.67%. Across all studies, 2 cases of osteonecrosis were reported. Four studies reported improvement in Harris hip scores. However, only 1 study reported a statistically significant improvement. Three studies reported improvement in SF-12 scores, of which 2 reported a significant improvement. One study reported significant improvement in UCLA hip score. Two studies reported postoperative Oxford hip scores, but no preoperative values were reported. None of the reviewed studies r
Although metal-on-metal total hip arthroplasty (MOM THA) has been used for over 3 decades, substantial improvements in manufacturing and design have led to improved durability with modern implants. Reported advantages of the use of MOM THA include very low wear and subsequent osteolysis, increased range of motion to impingement secondary to the availability of larger diameter femoral heads, and the
Raymond H. Kim; Douglas A. Dennis; Joshua T. Carothers
The success achieved with non-cemented hip arthroplasty depends mainly on the stability of the fixation, the quality of the stabilizing bone being just as important as favourable biomechanical conditions. The results of the intensive research and development with respect to the particular features of a non-cemented hip endoprosthesis can be divided into the following basic categories: Biomechanical aspects with special reference to bone related to the design of the prosthesis; material characteristics, such as fatigue strength, tribology, corrosion resistance, and biocompatibility; and development of new materials and coatings to permit direct bonding of implant and bone. With regard to the stem of hip prostheses, the different design parameters of various types are examined to determine their typical design characteristics, such as bearing surface of the collar, geometry of cross section, anatomically adapted shaping, and surface of the implant forming the contact with the bone. The latter can be divided into macroprofiles and macro- and micro-porous coated surfaces. On the other hand, the methods of cementless fixation of acetabular cups can be primarily divided into conical and spherical screw fixation and pegged fixation with additional macroprofiles of porous surfaces. In a separate study of the biomechanical aspects of screwed sockets, the special importance of socket shape and thread geometry are presented with reference to primary stability and long-term fixation of prostheses. PMID:3627790
Ungethüm, M; Blömer, W
Recent studies suggest that the tapered interface between stem and femoral head may be a substantial source of cobalt and chromium ion release after metal-on-metal (MOM) total hip arthroplasty (THA). This study compared patient ion levels after MOM hip resurfacing (HR) and MOM THA performed with identical acetabular components. 110 HRs were compared with 22 THAs. All had well-oriented components, unilateral implants, and serum ion studies beyond one year post-operatively. The HR group's median cobalt value was 1.11 ?g/L vs. 2.86 ?g/L for the THA patients. The HR group's median chromium value was 1.49 ?g/L vs. 2.94 ?g/L for THA. Significantly higher THA ion levels suggest a source of ions other than the MOM bearing itself. PMID:23618754
Johnson, Alicia J; Le Duff, Michel J; Yoon, James P; Al-Hamad, Mariam; Amstutz, Harlan C
In a series of 57 hemiplegic patients who subsequently fractured their hips, it was found that hip fracture occurred significantly more often on the hemiplegic side. Hip fracture was equally common in right- and left-sided hemiplegia, and often occurred within one year of the stroke. Two factors seem to be important in the genesis of hip fractures in hemiplegic patients:
G. Mulley; A. J. Espley
Total hip arthroplasty, or surgical replacement of the hip joint with an artificial prosthesis, is a reconstructive procedure that has improved the management of those diseases of the hip joint that have responded poorly to conventional medical therapy. In this review we briefly summarize the evolution of total hip arthroplasty, the design and development of prosthetic hip components, and the current clinical indications for this procedure. The possible complications of total hip arthroplasty, its clinical performance over time, and future directions in hip replacement surgery are also discussed. Images
Siopack, J S; Jergesen, H E
In hip implants, UHMWPE (ultra high molecular weight polyethylene) liner wear is believed to be a key issue affecting the lifetime of the artificial joint. Dual mobility, a THA (total hip arthroplasty) concept where the liner moves inside the metallic shell, has become popular due to its low dislocation rate. To understand the tribological behavior of this particular implant, especially
J. Geringer; B. Boyer; F. Farizon
Introduction: The dynamic helical hip system (DHHS; Synthes, Paoli, Pennsylvania) differs from the standard dynamic sliding hip screw (SHS) in that in preparing for its insertion, reaming of the femoral head is not performed, thereby preserving bone stock. It also requires less torque for insertion of the helical screw. The associated plate has locking options to allow locking screw fixation in the femoral shaft, thereby decreasing the chance of the plate pulling off. While biomechanical studies have shown improved resistance to cutout and increased rotational stability of the femoral head fragment when compared with traditional hip lag screws, there is limited information on clinical outcome of the implant available in the literature. Methods: We report a single surgeon series of 87 patients who were treated for their per-trochanteric hip fractures with this implant to evaluate their clinical outcome and compare it with a cohort of 344 patients who were treated with the standard SHS. All data were prospectively collected, most as part of a structured Geriatric Fracture Care Program. Results: The 2 groups were similar demographically, and medically, with similar rates of in-hospital complications and implant failure. Failure in the DHHS group was attributable to use of the implant outside its indications and repeated fall of the patient. Conclusion: This limited case series showed that the DHHS outcomes are comparable with that of the SHS. Whether there is any benefit to its use will require larger, prospective randomized controlled trials.
O'Malley, Natasha T.; Deeb, Andrew-Paul; Bingham, Karilee W.; Kates, Stephen L.
A modular grid welding fixture for a spacer grid that facilitates full grid laser welding of a spacer grid in one setup is disclosed. The modular design allows for partial implementation of each weld type. A base plate is used for mounting to the positioning\\/rotational plate of the welding system. A removable sub-plate received in the base plate is used
M. W. Anderson; J. S. Whitt
BACKGROUND: Osteoarthritis of the hip is successfully treated by total hip arthroplasty with metal-on-polyethylene articulation. Polyethylene wear debris can however lead to osteolysis, aseptic loosening and failure of the implant. Large head metal-on-metal total hip arthroplasty may overcome polyethylene wear induced prosthetic failure, but can increase systemic cobalt and chromium ion concentrations. The objective of this study is to compare
Wierd P Zijlstra; Nanne Bos; Jos JAM van Raaij
Background: Periprosthetic infection is a serious complication in total hip and knee arthroplasty. The complex therapeutic approach within two-stage reimplantation includes the use of antibiotic-impregnated spacers (temporary joint replacements). The aim of this paper was to evaluate bacteriological findings in selected patients with periprosthetic infection in whom a ready-made gentamicin-impregnated spacer was used to treat the infection.Materials and methods: Between 2008 and 2012, a ready-made, gentamicin-impregnated cement spacer was used in 24 patients to treat periprosthetic hip or knee infection within two-stage reimplantation. All components of the prosthesis and periprosthetic tissue samples were sent for microbiological examination at the first revision surgery, while at the second revision surgery, the spacer and surrounding tissue samples were sent in. In six patients with an inserted knee spacer, the level of gentamicin in the joint fluid was measured. Subsequently, the patients were regularly monitored. Results: Twenty-two (92%) of 24 patients were bacteriologically positive by culture. The most commonly detected causative agents were coagulase-negative staphylococci. Other isolates were Staphylococcus aureus, Corynebacterium, anaerobic bacteria, and Salmonella serotype Enteritidis. Nineteen (76%) of 25 primary pathogens were gentamicin sensitive. Spacers from two patients were culture positive for coagulase-negative staphylococci that tested resistant to gentamicin. During the follow-up of at least two years, none of the patients developed another periprosthetic infection.Conclusion: The success rate of two-stage-reimplantation total hip and knee arthroplasty using ready-made, gentamicin-impregnated spacers was 100 % in our cohort of patients; no other periprosthetic infection was reported during the follow-up of at least two years. From the bacteriological results, it appears that the ready-made, gentamicin-impregnated spacer only covers 76 % of the range of the causative agents. The solution would be to use a spacer impregnated with a combination of vancomycin and gentamicin that would be effective against all cultured species. Keywords: total hip arthroplasty - total knee arthroplasty - periprosthetic joint infection - two-stage reimplantation - gentamicin-impregnated spacer. PMID:25025681
Pro?ek, T; Ryšková, L; Ku?era, T; Srot, J; Sponer, P; Gallo, J; Plíšková, L
The incidence of squeaking in hip replacement varies for ceramic-on-ceramic and metal-on-metal bearings, and the implications are not fully understood. Contributing factors may include component malposition, edge loading, impingement, third-body particles, and loss of lubrication. However, squeaking is multifactorial, requiring a certain combination of interaction among patient, surgical, and implant factors. When squeaking is infrequent and function is not impaired, patients should avoid activities that precipitate the squeaking. Surgery is recommended for persistent or troublesome squeaking, severe malpositioning of components, failure of the implants (including fracture), impingement and subluxation, and pain. If necessary, the bearing can be changed during surgery to another ceramic-on-ceramic or to a ceramic-on-polyethylene bearing. PMID:20511437
Walter, William L; Yeung, Eric; Esposito, Christina
We report a case of a 63-year-old man who presented an end stage hip osteoarthritis 42?years after a proximal femoral osteotomy performed for the treatment of an intracapsular femoral neck fracture. A cemented total hip arthroplasty was implanted using a standard posterior approach. The osteotomy hardware was totally covered with a new cortical bone formation. A layer of bone tissue was removed, the screw heads were broken and the nail plate was also removed. The screw threaded portions were retained because they did not interfere with cemented femoral stem implantation. Fourteen years after total hip arthroplasty, the patient reported no pain and expressed high satisfaction with the surgery. The hip radiograph showed wear of the polyethylene cup and no periprosthetic osteolysis. Retention of hardware can be considered, especially in patients who have had hardware for several years, without any negative symptoms. PMID:24990849
Judas, Fernando Monteiro; Rodrigues, Joana Bento; Lucas, Francisco Manuel; Freitas, João Paulo
Interest is significant in patient-specific implants with the possibility of guided tissue regeneration, particularly for load-bearing implants. For such implants to succeed, novel design approaches and fabrication technologies that can achieve balanced mechanical and functional performance in the implants are necessary. This article is focused on porous load-bearing implants with tailored micro-as well as macrostructures using laser-engineered net shaping (LENS™), a solid freeform fabrication or rapid prototyping technique that can be used to manufacture patient-specific implants. This review provides an insight into LENS, some properties of porous metals, and the potential applications of this process to fabricate unitized structures which can eliminate longstanding challenges in load-bearing implants to increase their in-vivo lifetime, such as in a total hip prosthesis.
Vamsi Krishna, B.; Xue, Weichang; Bose, Susmita; Bandyopadhyay, Amit
Rhizarthrosis is the most common degenerative joint disease of the hand, affecting about 10% of the population. We report our results with trapezium replacement using a pyrocarbon spacer. Between January 2005 and April 2010, 70 patients underwent trapeziectomy with interposition of a pyrocarbon spacer. Sixty patients were examined at an average follow-up of 23.6 (5-64) months after the operation. Six (8.6%) of the 70 implanted pyrocarbon spacers dislocated. Based on the assessment scale devised by Buck-Gramcko, 19 patients achieved a very good outcome (31.6%), 31 patients (51.6%) had a good outcome, six results were satisfactory (10%) and four patients (6.6%) had a poor result. In this study, trapeziectomy and implantation of a pyrocarbon spacer achieved good or very good results in 83.2% of cases. The high cost of the implant and the observed rate of spacer dislocation should however be considered critically. While the short-term results of this method are encouraging, long-term outcomes will show whether this technique can keep up with the good results of suspension arthroplasty. PMID:24563969
Szalay, Gabor; Meyer, Christof; Scheufens, Tanja; Schnettler, Reinhard; Christ, Ralph; Schleicher, Iris
A pilot study has shown that there is usually but not invariably a fall in systemic arterial blood pressure within 90 seconds of implanting acrylic cement into the femoral shaft during hip arthroplasty. There is usually no change in arterial blood pressure on implanting acrylic cement into the acetabulum. The observed hypotension may be due to absorption of monomer or
Hugh Phillips; Peter V. Cole; Alan W. F. Lettin
Time-Action Analysis (TAA) of the Surgical Technique Implanting the Collum Femoris Preserving (CFP) Hip Arthroplasty. TAASTIC trial Identifying pitfalls during the learning curve of surgeons participating in a subsequent randomized controlled trial (An observational study)
Background Two types of methods are used to assess learning curves: outcome assessment and process assessment. Outcome measures are usually dichotomous rare events like complication rates and survival or require an extensive follow-up and are therefore often inadequate to monitor individual learning curves. Time-action analysis (TAA) is a tool to objectively determine the level of efficiency of individual steps of a surgical procedure. Methods/Design We are currently using TAA to determine the number of cases needed for surgeons to reach proficiency with a new innovative hip implant prior to initiating a multicentre RCT. By analysing the unedited video recordings of the first 20 procedures of each surgeon the number and duration of the actions needed for a surgeon to achieve his goal and the efficiency of these actions is measured. We constructed a taxonomy or list of actions which together describe the complete surgical procedure. In the taxonomy we categorised the procedure in 5 different Goal Oriented Phases (GOP): 1. the incision phase 2. the femoral phase 3. the acetabulum phase 4. the stem phase 5. the closure pase Each GOP was subdivided in Goal Oriented Actions (GOA) and each GOA is subdivided in Separate Actions (SA) thereby defining all the necessary actions to complete the procedure. We grouped the SAs into GOAs since it would not be feasible to measure each SA. Using the video recordings, the duration of each GOA was recorded as well as the amount of delay. Delay consists of repetitions, waiting and additional actions. The nett GOA time is the total GOA time – delay and is a representation of the level of difficulty of each procedure. Efficiency is the percentage of nett GOA time during each procedure. Discussion This allows the construction of individual learning curves, assessment of the final skill level for each surgeon and comparison of different surgeons prior to participation in an RCT. We believe an objective and comparable assessment of skill level by process assessment can improve the value of a surgical RCT in situations where a learning curve is expected.
van Oldenrijk, Jakob; Schafroth, Matthias U; Bhandari, Mohit; Runne, Wouter C; Poolman, Rudolf W
Background The CRISPR/Cas system is known to act as an adaptive and heritable immune system in Eubacteria and Archaea. Immunity is encoded in an array of spacer sequences. Each spacer can provide specific immunity to invasive elements that carry the same or a similar sequence. Even in closely related strains, spacer content is very dynamic and evolves quickly. Standard models of nucleotide evolution cannot be applied to quantify its rate of change since processes other than single nucleotide changes determine its evolution. Methods We present probabilistic models that are specific for spacer content evolution. They account for the different processes of insertion and deletion. Insertions can be constrained to occur on one end only or are allowed to occur throughout the array. One deletion event can affect one spacer or a whole fragment of adjacent spacers. Parameters of the underlying models are estimated for a pair of arrays by maximum likelihood using explicit ancestor enumeration. Results Simulations show that parameters are well estimated on average under the models presented here. There is a bias in the rate estimation when including fragment deletions. The models also estimate times between pairs of strains. But with increasing time, spacer overlap goes to zero, and thus there is an upper bound on the distance that can be estimated. Spacer content similarities are displayed in a distance based phylogeny using the estimated times. We use the presented models to analyze different Yersinia pestis data sets and find that the results among them are largely congruent. The models also capture the variation in diversity of spacers among the data sets. A comparison of spacer-based phylogenies and Cas gene phylogenies shows that they resolve very different time scales for this data set. Conclusions The simulations and data analyses show that the presented models are useful for quantifying spacer content evolution and for displaying spacer content similarities of closely related strains in a phylogeny. This allows for comparisons of different CRISPR arrays or for comparisons between CRISPR arrays and nucleotide substitution rates.
This dissertation explores and discusses different aspects of blood loss and blood-saving measures in total hip and knee arthroplasty.\\u000a\\u000a \\u000a\\u000aBackground: Worldwide, approximately \\u000a\\u000a1 million total hip and 1 million total knee prostheses are implanted each year. Total hip arthroplasty and total knee arthroplasty are associated with a considerable amount of total blood loss. Postoperative anemia may seriously impede functional mobility
W. G. Horstmann
The aim of the present study was to evaluate the efficacy of the vacuum-assisted closure (V.A.C.) system in the treatment of early hip joint infections. 28 patients (11 m/17 f; mean age 71 y. [43-84]) with early hip joint infections have been treated by means of the V.A.C.-therapy. At least one surgical revision [1-7] has been unsuccessfully performed for infection treatment prior to V.A.C.-application. Pathogen organisms could have been isolated in 22/28 wounds. During revision, cup inlay and prosthesis head have been exchanged and 1-3 polyvinylalcohol sponges inserted into the wound cavity/ periprosthetically at an initial continuous pressure of 200 mm Hg. Postoperatively, a systemic antibiosis was given according to antibiogram. 48-72 h after surgery an alteration from haemorrhagic to serous fluid was observed in the V.A.C.-canister. Afterwards, the pressure was decreased to 150 mm Hg and remained at this level till sponge removal. After a mean period of 9 [3-16] days the inflammation parameters have been retrogressive and the sponges were removed. An infection eradication could be achieved in 26/28 cases. In the two remaining cases the infected prosthesis had to be explanted and a gentamicin-vancomycin-loaded spacer has been implanted, respectively. At a total mean follow-up of 36 [12-87] months no reinfection or infection persistence was observed. The V.A.C.-system can be a valuable contribution in the treatment of early joint infections when properly used. Indications should be early infections with well-maintained soft-tissues for retention of the negative atmospheric pressure. PMID:19834589
Kelm, Jens; Schmitt, Eduard; Anagnostakos, Konstantinos
Patients with hip fracture typically present to the emergency department or their physician's office after a fall. They are often unable to walk, and they may exhibit shortening and exter- nal rotation of the affected limb. Frequently, they have hip pain. In some instances, however, patients with hip fracture may complain only of vague pain in their buttocks, knees, thighs,
LANCE C. BRUNNER; LIZA ESHILIAN-OATES; TONY Y. KUO; David Geffen; RADIOLOGIC DECISION-MAKING
A snapping hip is a common problem in children and young adults. The common etiologies of the syndrome have been well described. We believe that habitual dislocation may be a more frequent cause of the snapping hip syndrome than has been previously described. We report two cases of this rarely reported clinical entity presenting as a snapping hip. PMID:1860960
Stuart, P R; Epstein, H P
Background: Failed intertrochanteric fractures in elderly patients are surgical challenge with limited options. Hip arthroplasty is a good salvage procedure even though it involves technical issues such as implant removal, bone loss, poor bone quality, trochanteric nonunion and difficulty of surgical exposure. Materials and Methods: 30 patients of failed intertrochanteric fractures where hip arthroplasty was done between May 2008 and December 2011 were included in study. 13 were males and 17 were females with average age of 67.3 years. There were 2 cemented bipolar arthroplasties, 19 uncemented bipolar, 4 cemented total hip arthroplasty and 5 uncemented total hip arthroplasties. 16 patients had a trochanteric nonunion, which was treated by tension band principles. Total hip was considered where there was acetabular damage due to the penetration of implant. Results: The average followup was 20 months (range 6-48 months). Patients were followed up from 6 to 48 months with average followup of 20 months. None of the patients were lost to followup. There was no dislocation. All patients were ambulatory at the final followup. Conclusion: A predictable functional outcome can be achieved by hip arthroplasty in elderly patients with failed intertrochanteric fractures. Though technically demanding, properly performed hip arthroplasty can be a good salvage option for this patient group.
Pachore, Javahir A; Shah, Vikram I; Sheth, Ashish N; Shah, Kalpesh P; Marothi, Dhiraj P; Puri, Rahul
The prevention of fractures amongst older people consists of (i) prevention and treatment of osteoporosis, (ii) prevention of falling and (iii) prevention of fractures using injury-site protection. As the great majority of hip fractures are caused by a sideways fall with direct impact on the greater trochanter of the proximal femur, one approach to prevention is the use of an adequately configured padded, firm-shield external hip protector. With this type of two-part design, the impacting force and energy are, at the time of the fall-impact, first weakened by the padding part of the protector and then diverted away from the greater trochanter by the shield part of the same. Following this line, a series of consecutive studies by the Accident & Trauma Research Center at the UKK Institute, Tampere, Finland, found that a padded, strong-shield hip protector was effective in preventing hip fractures. In the context of the wider literature on hip protectors, these more encouraging results suggest the need for a more rigorous regulation of protector design and characteristics. Alongside inadequacies of design, the other most frequent general problem with hip protectors is compliance. Not all elderly people with a high risk of hip fracture will agree to use hip protectors and in those who do, long-term adherence may decrease. Caregiver motivation and involvement appear therefore to be crucial. PMID:16926206
Kannus, Pekka; Parkkari, Jari
Background The purpose of our study was to prospectively report the clinical results of 280 consecutive hips (240 patients) who received a ReCap Hip Resurfacing System implant (Biomet Inc., Warsaw, USA) in a single district general hospital. Literature reports a large variation in clinical results between different resurfacing designs and published results using this particular design are scarce. Methods Mean follow up was 3.3 years (1.0 to 6.3) and four patients were lost to follow-up. All patients were diagnosed with end-stage hip osteoarthritis, their mean age was 54 years and 76.4% of all patients were male. Results There were 16 revisions and four patients reported a Harris Hip Score <70 points at their latest follow up. There were no pending revisions. Kaplan-Meier implant survival probability, with revision for any reason as endpoint, was 93.5% at six years follow-up (95%-CI: 88.8-95.3). There were no revisions for Adverse Reactions to Metal Debris (ARMD) and no indications of ARMD in symptomatic non-revised patients, although diagnostics were limited to ultrasound scans. Conclusions This independent series confirms that hip resurfacing is a demanding procedure, and that implant survival of the ReCap hip resurfacing system is on a critical level in our series. In non-revised patients, reported outcomes are generally excellent. Trial registration ClinicalTrials.gov Identifier: NCT00603395
Thirty-nine cementless hip arthroplasties using metal-on-metal articulation were consecutively implanted in 30 patients less than 50 years of age and compared with a matched control group (by age, diagnosis, Devane activity, and Harris hip scores) of cementless arthroplasties using ceramic-on-polyethylene articulation. The Harris hip score at follow-up (minimum 5 years) for the metal-on-metal was 94.9 (range, 74–100). After the same
Henri Migaud; Alexandre Jobin; Christophe Chantelot; François Giraud; Philippe Laffargue; Antoine Duquennoy
A description is given of a spacer grid made of strip components fitted ; into each other in toothlike fashion forming cells for elongated fuel pins which ; are held in a bundle by axes running parallel to one another. (GE);
B. Leaver; W. Mercer
Many early metal-on-polyethylene hip resurfacing arthroplasty designs were abandoned after reports of high short-term and\\u000a midterm failure rates. To investigate factors associated with failure, we retrospectively reviewed our experience with early-design\\u000a hip resurfacing implants in 75 patients during a 25-year period (median followup, 7.9 years; range, 0.1–25.2 years). Implant\\u000a failure was defined as revision for any reason. One of 75 patients was
Eric J. Yue; Miguel E. Cabanela; Gavan P. Duffy; Michael G. Heckman; Mary I. O’Connor
To investigate the biomechanical effect of collars, finite element analyses are carried out through two hip joints that are implanted using collared and collarless stems, respectively, and an intact hip joint model. For the analyses, the sacrum, coxal bone, and the cancellous and cortical bones of a femur are modelled using finite elements based on X-ray computed tomographic images taken
Insu Jeon; Ji-Yong Bae; Jin-Hong Park; Taek-Rim Yoon; Mitsugu Todo; Masaaki Mawatari; Takao Hotokebuchi
Background: A ceramic femoral head is an alternative to a metal femoral head for the bearing surface of total hip ar- throplasty. The purpose of this study was to compare polyethylene wear in patients who had undergone bilateral total hip arthroplasty with implants that differed only with regard to the material used for the femoral head: a zirconia head was
This author's development of metal/metal hip resurfacing began in 1989, with the first patient implantation in February 1991. In the first three years a pilot study identified optimum fixation as hydroxyapatite coated uncemented cups and cemented femoral components. From March 1994 hybrid fixed components have been used. These implants have generally been satisfactory with respect to fixation but high wear of the bearing, metallosis and osteolysis have been seen with some components inserted during 1996, a period during which the metal microstructure was altered by the heat processes, hot isostatic pressing and solution heat treatment. The Birmingham Hip Resurfacing was developed taking account of experience with earlier resurfacing designs. This implant employs hybrid fixation with a porous ingrowth acetabular component and has an as-cast metal microstructure having had no post casting heat treatments. During the past 4 years the author has performed over 1,000 Birmingham Hip Resurfacingís with a total failure rate of less than 1.0%. PMID:24030583
McMinn, D J W
The orientation of the acetabular component is influenced not only by the orientation at which the surgeon implants the component, but also the orientation of the pelvis at the time of implantation. Hence, the orientation of the pelvis at set-up and its movement during the operation, are important. During 67 hip replacements, using a validated photogrammetric technique, we measured how three surgeons orientated the patient's pelvis, how much the pelvis moved during surgery, and what effect these had on the final orientation of the acetabular component. Pelvic orientation at set-up, varied widely (mean (± 2, standard deviation (sd))): tilt 8° (2sd ±32), obliquity -4° (2sd ±12), rotation -8° (2sd ±14). Significant differences in pelvic positioning were detected between surgeons (p < 0.001). The mean angular movement of the pelvis between set-up and component implantation was 9° (sd 6). Factors influencing pelvic movement included surgeon, approach (posterior > lateral), procedure (hip resurfacing > total hip replacement) and type of support (p < 0.001). Although, on average, surgeons achieved their desired acetabular component orientation, there was considerable variability (2sd ±16) in component orientation. We conclude that inconsistency in positioning the patient at set-up and movement of the pelvis during the operation account for much of the variation in acetabular component orientation. Improved methods of positioning and holding the pelvis are required. Cite this article: Bone Joint J 2014; 96-B:876-83. PMID:24986939
Grammatopoulos, G; Pandit, H G; da Assunção, R; Taylor, A; McLardy-Smith, P; De Smet, K A; Murray, D W; Gill, H S
The authors present their experience with total hip replacement in patients with ankylosing spondylitis. In the period of 1985-1997 they performed in total 66 total hip replacements in 41 patients. Of the total number of the used implants 24 were fully cemented (the average follow-up - 13 years), 3 were hybrid and 39 cementless (the average follow-up - 6 years). The results of total hip replacements were assessed on the basis of Harris score (HS). The outcomes of the two subgroups, i. e. cemented and cementless implants, were statistically evaluated and compared. The group of hybrid implants was not statistically evaluated due to a small size of the subgroup. In both evaluated groups of implants the results were very favourable (the average HS value in cemented: 86,2 in cementless: 86,4). The occurrence of periarticular ossifications was minimal in both groups. Of the post-operative complications we recorded one case of displacement of the implant which was solved by closed reduction under general anesthesia. Two cases required re-operation of the loosened cementless cup. There occurred no infect. On the basis of the evaluation of the average 13-year results of cemented implants the use of this type of total hip replacement in patients with M. Bechterev is recommended. The question remains whether the same positive values will be produced after the same time interval also by cementless implants as we still do not have results from a 10-year follow-up. Key words: ankylosing spondylitis, total hip replacement. PMID:20478223
Jezek, V; Vavrík, P; Popelka, S; Urbanová, Z
IntroductionStudies of hip arthroplasty have dealt mainly with total endoprosthesis, while tribology measurement values of hemi-endoprosthetic implants are rare. The small amount of experimental tribological data concerning materials of hemi-endoprosthetic implants in the form of pendulum trials, animal experiments, in vivo measurements on human hip joints and pin on disc studies report friction coefficients between 0.014 and 0.57; the friction
L. P. Müller; J. Degreif; L. Rudig; D. Mehler; H. Hely; P. M. Rommens
Unconstrained tripolar hip implants provide an additional bearing using a mobile polyethylene component between the prosthetic\\u000a head and the outer metal shell. Such a design increases the effective head diameter and therefore is an attractive option\\u000a in challenging situations of unstable total hip arthroplasties. We report our experience with 54 patients treated using this\\u000a dual mobility implant in such situations.
Olivier Guyen; Vincent Pibarot; Gualter Vaz; Christophe Chevillotte; Jacques Béjui-Hugues
Background Metal-on-metal (MOM) hip resurfacing arthroplasty (HRA) is in clinical use as an appropriate alternative to total hip arthroplasty in young patients. In this technique, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the acetabulum. Objectives The primary objective of this analysis was to compare the revision rates of MOM HRA using different implants with the benchmark set by the National Institute of Clinical Excellence (NICE). The secondary objective of this analysis was to review the literature regarding adverse biological effects associated with implant material. Review Methods A literature search was performed on February 13, 2012, to identify studies published from January 1, 2009, to February 13, 2012. Results The revision rates for MOM HRA using 6 different implants were reviewed. The revision rates for MOM HRA with 3 implants met the NICE criteria, i.e., a revision rate of 10% or less at 10 years. Two implants had short-term follow-ups and MOM HRA with one of the implants failed to meet the NICE criteria. Adverse tissue reactions resulting in failure of the implants have been reported by several studies. With a better understanding of the factors that influence the wear rate of the implants, adverse tissue reactions and subsequent implant failure can be minimized. Many authors have suggested that patient selection and surgical technique affect the wear rate and the risk of tissue reactions. The biological effects of high metal ion levels in the blood and urine of patients with MOM HRA implants are not known. Studies have shown an increase in chromosomal aberrations in patients with MOM articulations, but the clinical implications and long-term consequences of this increase are still unknown. Epidemiological studies have shown that patients with MOM HRA implants did not have an overall increase in mortality or risk of cancer. There is insufficient clinical data to confirm the teratogenicity of MOM implants in humans. Conclusions Metal-on-metal HRA can be beneficial for appropriately selected patients, provided the surgeon has the surgical skills required for performing this procedure. Plain Language Summary There are many young patients with hip diseases who need to have hip replacement surgery. Although a traditional hip replacement is an acceptable procedure for these patients, some surgeons prefer using a newer technique in young patients called hip resurfacing. In this technique, instead of removing the head of the femoral bone, a metal cap is placed on the femoral head to cover the damaged surface of the bone and a metal cup is placed in the hip socket, similar to the cups used in traditional hip replacement. The analysis of the revision rates (i.e., how soon and in how many patients the surgery needs to be redone) and safety of resurfacing implants showed that generally these implants can last 10 years or more for the majority of young people. Good outcomes can be expected when skilled surgeons perform the surgery in properly selected patients. However, since these implants are made of metal (cobalt and chromium alloy), there is concern about excess metal debris production due to friction between the 2 metal components leading to high levels of metal ions in the blood and urine of patients. The production of metal debris may result in inflammation in the joint or development of a benign soft tissue mass leading to implant failure. However, it has been shown that this risk can be reduced by proper positioning of the implant and the careful selection of patients for this procedure. Little is known about the long-term biological effects of high levels of metal ions in the blood and urine of patients who have received metal implants. There is concern about potential increases in the risk of cancer and the risk of fetal abnormalities, but these effects have not been established yet. However, since cobalt and chromium can pass the placental barrier, implants that are not metal-on-metal are recommended for women at childbearing ages if they
Sehatzadeh, S; Kaulback, K; Levin, L
Patients with standard total hip arthroplasties may have reduced hip abduction and extension moments when compared with normal nonosteoarthritic hips. In comparison, patients after resurfacing total hip arthroplasty appear to have a near-normal gait. The authors evaluated temporal-spatial parameters, hip kinematics, and kinetics in hip resurfacing patients compared with patients with unilateral osteoarthritic hips and unilateral standard total hip arthroplasties.
Michael A. Mont; Thorsten M. Seyler; Phillip S. Ragland; Roland Starr; Jochen Erhart; Anil Bhave
Background This study examines the clinical and radiologic results of ceramic-on-ceramic total hip arthroplasties with regard to wear, osteolysis, and fracture of the ceramic after a minimum follow-up of six years. Methods We evaluated the results of a consecutive series of 148 primary ceramic-on-ceramic total hip arthroplasties that had been performed between May 2001 and October 2005 in 142 patients. The mean age was 57.2 years (range, 23 to 81 years). The mean follow-up period was 7.8 years (range, 6.1 to 10.1 years). Preoperative diagnosis was avascular necrosis in 77 hips (52%), degenerative arthritis in 36 hips (24.3%), femur neck fracture in 18 hips (12.2%), rheumatoid arthritis in 15 hips (10.1%), and septic hip sequelae in 2 hips (1.4%). Clinical results were evaluated with the Harris hip score, and the presence of postoperative groin or thigh pain. Radiologic analysis was done with special attention in terms of wear, periprosthetic osteolysis, and ceramic failures. Results The mean Harris hip score improved from 58.3 (range, 10 to 73) to 92.5 (range, 79 to 100) on the latest follow-up evaluation. At final follow-up, groin pain was found in 4 hips (2.7%), and thigh pain was found in 6 hips (4.1%). Radiologically, all femoral stems demonstrated stable fixations without loosening. Radiolucent lines were observed around the stem in 25 hips (16.9%), and around the cup in 4 hips (2.7%). Endosteal new bone formation was observed around the stem in 95 hips (64.2%) and around the cup in 88 hips (59.5%). No osteolysis was observed around the stem and cup. There were 2 hips (1.4%) of inclination changes of acetabular cup, 2 hips (1.4%) of hip dislocation, 1 hip (0.7%) of ceramic head fracture, and 1 hip (0.7%) of squeaking. The Kaplan-Meier survival rate of the prostheses was 98.1% at postoperative 7.8 years. Conclusions The ceramic-on-ceramic total hip arthroplasty produced excellent clinical results and implant survival rates with no detectable osteolysis on a minimum six-year follow-up study. The ceramic-on-ceramic couplings could be a reasonable option of primary total hip arthroplasty for variable indications.
Choy, Won-Sik; Lee, Sang Ki; Bae, Kyoung Wan; Hwang, Yoon Sub; Park, Chang Kyu
Background and purpose Metaphyseal anchored short-stem hip implants were designed to improve load transmission and preserve femoral bone stock. Until now, only few outcome data have been available and migration studies are one of the few ways of obtaining data that are predictive of implant survival. We therefore evaluated a metaphyseal anchored short-stem hip implant by Ein Bild Roentgen Analyse femoral component analysis (EBRA-FCA). Patients and methods First, the EBRA-FCA method was validated for the short-stem hip implant. Then 80 of the first 100 consecutive implants were evaluated after at least 2 years. Clinical assessment was performed using the WOMAC and the UCLA score. Results After 2.7 (2.0–4.2), years none of the implants had been revised and by that time the stems had subsided by a mean of 0.7 mm (SD 1.8) (95% CI: 0.3–1.1). Of the 80 implants, 78 were stable after 2 years, with 74 being primary stable and 4 showing secondary stabilization after initial subsidence. Continuous migration was seen in only 2 patients. The clinical outcome showed good results with a mean WOMAC of 11 (SD 13) and a mean UCLA score of 7.3 (SD 2.0). [OK?] Interpretation The metaphyseal anchored short-stem hip implant showed good functional results and a high degree of stability after 2 years. The outcome is comparable to that of clinically proven conventional hip implants and if the results are confirmed by long-term studies, short-stem hip arthroplasty might be an alternative for young patients requiring hip replacement.
Background contextInterbody spacers for anterior spine fusion are made of different materials, which can affect the postfusion magnetic resonance imaging (MRI) scans. Susceptibility artifacts specially for metallic implants can decrease the image quality.
Thorsten Ernstberger; Gabert Heidrich; Gottfried Buchhorn; Bioengineer
The metal-on-metal bearing couple in having a resurgence in clinical applications seen in both total hip resurfacing technologies. The most noteworthy advantage of a metal-on-metal implant is the improved wear characteristics seen both in vitro on wear simulators and in vivo with retrieved implants. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concerns exist regarding the generation
S. J. MacDonald
Sequences for the spacer regions that separate the 16S and 23S ribosomal RNA genes have been determined for four more (strategically placed) archaebacteria. These confirm the general rule that methanogens and extreme halophiles have spacers that contain a single tRNAala gene, while tRNA genes are not found in the spacer region of the true extreme thermophiles. The present study also shows that the spacer regions from the sulfate reducing Archaeglobus and the extreme thermophile Thermococcus (both of which cluster phylogenetically with the methanogens and extreme halophiles) contain each a tRNAala gene. Thus, not only all methanogens and extreme halophiles show this characteristic, but all organisms on the "methanogen branch" of the archaebacterial tree appear to do so. The finding of a tRNA gene in the spacer region of the extreme thermophile Thermococcus celer is the first known phenotypic property that links this organism with its phylogenetic counterparts, the methanogens, rather than with its phenotypic counterparts, the sulfur-dependent extreme thermophiles.
Achenbach-Richter, L.; Woese, C. R.
In an electrostatic precipitator having adjacent first and second curtains, the improvement is described comprising a spacer inserted between the first and second curtains to effect straightening of the curtains when warped. It also prevents further curtain warpage, each curtain having a top edge and being disposed substantially parallel with the adjacent curtain. The spacer comprises: (a) a hanger comprising first suspending means secured at one end to engage and to suspend the hanger from the top edge of the first curtain, and second suspending means spaced from the first suspending means; and (b) at least one hanging member having third suspending means for engaging the second suspending means and suspending the hanging member from and below the hanger. A method is described of installing a spacer between adjacent first and second curtains of an electrostatic precipitator to effect a gradual straightening of any warpage therein.
Aseptic loosening of total hip arthroplasty is still a serious problem. Bone qualitiy might be one of the major factors influencing loosening. In a previous study, bone loss during the reparation phase was evaluated with modified computed tomography at the site of the implant. The present study documents the degree of disuse osteoporosis prior to and after surgery. Bone density
P Riiegseggerl; P. Seitz; N. Gschwend; L. Dubs
Many periprosthetic fractures about the hip and knee can be managed successfully with modern internal fixation techniques; however, there are particular circumstances when revision arthroplasty is a better choice. These revision cases often require a substantial amount of preoperative planning and resources. Knowledge of the indications, techniques, and implants needed for managing these complex conditions is paramount for success. PMID:23395038
Haidukewych, George J; Langford, Joshua R; Liporace, Frank A
We prepared glucidoamphiphile derivatives from d-glucose, d-galactose and xylitol, in which the glucidic moiety and the hydrophobic alkyl chain are separated by spacer arm E (E=glyceryl, (OEt)2-?-polypropyleneglycyl and butyloxy). Their amphiphile characteristics are compared to those of the corresponding analogs 3-O-alkyl-d-glucopyranoses, 6-O-alkyl-d-galactopyranoses and 1-O-alkyl-d,l-xylitols. We discussed the spacer arm influence on hydrophobic lipophilic balance (HLB), critical micellar concentration (CMC), water
G Goethals; A Fernández; P Martin; M Miñana-Pérez; C Scorza; P Villa; P Godé
... 11.14 Read More Find a Cosmetic Dentist Teeth Whitening Accredited and General Member Dental Patients ? Cosmetic Procedures ? Dental Implants Dental Implants The ... key benefit of dental implants over other tooth replacement systems is that an implant connects directly ...
Surgical management of hip disease in adolescents and young to middle-aged adults is rapidly evolving, and a variety of operative techniques are needed to provide comprehensive care. The purpose of this study was to determine the utilization of surgical procedures and recent changes in procedure utilization in a comprehensive hip surgery program. We performed a retrospective review of 983 hip procedures in 854 patients performed over a seven year time period. The average patient age was 37.4 years (range 10-55). Five hundred fifty-six procedures were performed in female patients and 427 in male patients. Total hip arthroplasty (32.9%), hip arthroscopy (25.1%), and periacetabular osteotomy (13.1%) were the most common surgical procedures. Techniques utilized less often included osteochondroplasty of the femoral head-neck junction (7.9%), hip implant revisions (7.9%), and proximal femoral osteotomy (4.1%). Uncommon procedures included core decompression (2.2%), soft tissue releases (1.2%), femoral head resurfacing (0.6%), arthrodesis (0.3%,) and Chiari pelvic osteotomy (0.2%). The most dramatic changes in utilization over the seven year time period included a marked increase in hip arthroscopies and osteochondroplasties of the femoral head-neck junction. These data underscore the variety of surgical techniques needed to treat this patient population, and emphasize an expanding role for nonarthroplasty surgical interventions.
Clohisy, John C; Curry, Madelyn C; Fejfar, Shane T; Schoenecker, Perry L
Improvements in materials and fixation have addressed many of the limitations of resurfacing total hip arthroplasty (THA). The functional demands and the longevity of arthroplasty patients are increasing. Many patients have embraced the functional capacity, bone conservation, and revision options of hip resurfacing. Young men have historically been at increased risk for failure of total THA. In this patient subgroup,
Thomas P. Schmalzried
We have developed a four-dimensional (4D) model of the lower extremities after total hip arthroplasty in patients. The model can aid in preventing complications such as dislocation and wearing of the sliding surface. The skeletal structure and implant alignment were obtained from CT data. We applied registration method using CAD data to estimate accurate implant alignment from scattered CT data.
Yoshito Otake; Naoki Suzuki; Asaki Hattori; Keisuke Hagio; Nobuhiko Sugano; Kazuo Yonenobu; Takahiro Ochi
The reasons leading to the in vivo failure of three Acumatch M-series titanium-alloy modular implants in cementless total hip arthroplasty were investigated. The implants were in service for a period ranging from 18 to 36 months. Two were fractured in vivo and the other was retrieved secondary to aseptic loosening after 18 months in service. Macroscopic examination showed close topographical
Manish Paliwal; D. Gordon Allan; Peter Filip
Mechanical testing has been performed on total hip replacements implanted in sections of cadaveric femora. A purpose built transducer has been used to measure the rotation of the implant in the bone under loads applied in the anterior-posterior direction. This has been used to assess the effect of cement and also of retaining more of the femoral neck.The retention of
K E Tanner; W Bonfield; D Nunn; M A R Freeman
Newer arthroplasty designs claim to provide superior range of motion (ROM) and greater stability than their predecessors. However, there is no way to compare ROM of implant systems in an equivalent anatomical environment in a clinical setting. This study used computer-aided design to compare ROM after hip resurfacing, 28 mm THA, 36 mm THA, and anatomic dual mobility (ADM) THA in 3D models of 5 cadaver pelvises. ROM to impingement was then tested in 10 different motions and a one-way ANOVA was used to compare results. The hip resurfacing resulted in restricted ROM compared to the other 3 models in all motions except adduction. The ADM, 36 mm, and 28 mm THA resulted in similar ROM. Dual mobility constructs provide comparable ROM in patients where large head THA is not appropriate. PMID:23477855
Klingenstein, Gregory G; Yeager, Alyssa M; Lipman, Joseph D; Westrich, Geoffrey H
Computational spacer patterning technology (SPT) has been developed for the first time to address the challenges concerning hotspots and mask specifications in SPT. A simulation combined with a lithography, etching and deposition model shows the strong correlation of 0.999, 0.993, 0.980 with the experimental critical dimension (CD), mask error-enhancement factor (MEEF) and defect printability through a series of spacer processes, respectively. Furthermore, a design for manufacturability (DfM) flow using computational SPT can find hotspots caused by spacer patterning processes as well as those caused by lithography process and help designers make the circuit layout more robust. Besides, a newly defined MEEF and defect printability, which are primary metrics for mask specification, can be predicted so accurately by using computational SPT that the new scheme to determine appropriate mask specifications is shown to be feasible under the spacer patterning process condition. Thus, computational SPT is found to be promising for addressing the challenges concerning hotspot removal and mask specification in the upcoming 20-30nm node and beyond.
Mashita, Hiromitsu; Taguchi, Takafumi; Nakajima, Fumiharu; Iyanagi, Katsumi; Kotani, Toshiya; Mimotogi, Shoji; Inoue, Soichi
This patent describes a method of constructing a spacer for maintaining a matrix of vertically aligned fuel rods within a fuel bundle in side-by-side upstanding spatial relation, the spacer being of the class having vertical tubular members interconnected by a grid. It comprises providing upper and lower grid members, the grid members each comprising strips of metal having major surfaces vertically aligned parallel to the vertical direction of the fuel rods within the fuel bundle, the grid members forming a matrix of crossed members defining interstitial areas for receiving and bracing individual fuel rods passing through the spacer; providing a matrix of tubes, the matrix of tubes being aligned vertically with respect to the fuel rods within the fuel bundle and dispose for placement to interstitial locations between the fuel rods; notching the tubes at the upper and lower ends for receiving the grids; confronting the grids to the matrix of tubes at the upper and lower notches on the tubes; fastening the grids to the tubes for forming a unitary grid structure for the spacer.
This patent describes a nuclear reactor having fuel assemblies including an upper end fitting and a lower end fitting and spaced nuclear fuel rod spacer grids therebetween for supporting and spacing a plurality of elongated nuclear fuel rods, each of which includes a hollow active portion of nuclear fuel filled cladding intermediate the rod ends and a tapering end cap
S. C. Hatfield; M. G. Andrews; R. P. Broders
An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.
Grimes, Patrick G. (Westfield, NJ); Einstein, Harry (Springfield, NJ); Newby, Kenneth R. (Berkeley Heights, NJ); Bellows, Richard J. (Westfield, NJ)
Summary Total hip arthroplasty (THA) has been indicated as the surgical intervention with greatest improvement in pain and physical function. However some patients continue to experience hip pain after elective surgery. We investigate prognostic factors that negatively affect treatment effectiveness and the patient outcome. The “hip region” constitutes the groin, buttock, upper lateral thigh, greater trochanteric area, and the iliac crest. Pain originating from various sources and not directly linked to prosthesis may be perceived here and includes the lumbosacral spine, referred pain from abdominal organs and soft tissue sources such as trochanteric bursitis, tendinitis, hip abductor dysfunction, and inguinal hernia. An accurate assessment of the pain cause is extremely difficult to construct and a complete differential diagnosis is fundamental. We assess all the possible causes of hip pain after THA and we divide them depending on the presence or absence of radiographic signs.
Ferrata, Paolo; Carta, Serafino; Fortina, Mattia; Scipio, Daniele; Riva, Alberto; Di Giacinto, Salvatore
The snapping hip syndrome is a symptom complex characterized by hip pain and an audible snapping of the hip with exercise typically seen in young individuals. "External" and "internal" etiologies have been described, although the "internal" etiology is poorly understood. A clinical, radiographic, and anatomical study of eight patients with this disorder, secondary to an internal etiology, was undertaken to aid in the diagnosis and surgical treatment. Iliopsoas bursography with cineradiography revealed subluxation of the iliopsoas tendon to be an apparent cause of the snapping hip. The anatomy of the hip in relationship to the iliopsoas tendon is defined with the anterior inferior iliac spine, iliopectineal eminence, and lesser trochanter assuming a significant role in the syndrome. An operative approach involving a partial release and lengthening of the iliopsoas tendon, with minimal resection of a lesser trochanteric bony ridge, if involved, is described. PMID:6496831
Schaberg, J E; Harper, M C; Allen, W C
One reason why otherwise well functioning total hip replacements have a finite service life is eventual aseptic Ioosening of the implants because of osteolysis induced by wear particles from the artificial bearing. Pain and osteolysis from wear debris can manifest even in the absence of aseptic Ioosening. Total hip replacements with ceramic-on-ceramic articulations have shown less wear both in vitro
B. S. Bal; T. J. Aleto; J. P. Garino; A. Toni; K. J. Hendricks
Increasing data are available describing risk factors for the development of local and systemic adverse events following operations using metal-on-metal (MoM) hip implants. The prevalence and clinical relevance of metal-associated problems are, however, still under debate. They can be influenced by type and position of implant as well as patient-specific factors. Patients with small MoM heads (maximum diameter 32 mm) and subgroups of resurfacing arthroplasty can achieve good long-term survival. The use of large head MoM implants (diameters greater than 36 mm), however, is currently not advised due to the unsatisfactory results. PMID:23632650
Günther, K-P; Lützner, J; Hannemann, F; Schmitt, J; Kirschner, S; Goronzy, J; Stiehler, M; Lohmann, C; Hartmann, A
Retained intramedullary femoral nails can pose a problem for the implantation of the femoral component during total hip arthoplasty (THA) and they must often be removed. A patient with a retained Küntscher femoral nail implanted 47 years previously presented in our outpatient clinic for a THA. Since removal of the nail was impossible without severe damage to the femur, we chose to perform an extended trochanteric osteotomy, to cut the proximal part of the nail and to implant a cemented short stem with its tip in the hollow end of the nail. PMID:23547527
Goosen, Jon H M; Van Hellemondt, Gijs G
Parallel to the rise in the number of primary hip arthroplasties the number of complications is also increasing, especially aseptic loosening of cemented implants and uncemented implants with a smooth surface. The loosening of the implant is very often accompanied by the destruction of bone stock, which requires reconstruction.
On the base of 217 cases operated in the years 1997-2000 the authors present the methods of treating deficits in the proximal femur using special instruments, bone transplants, reconstructive systems, and revision prostheses. The so-called biological attitude to the problem is preferred. Operative tactics are presented in respect to bone deficits classified according to Mallory. PMID:17986956
Jab?o?ski, T; Górecki, A; Purski, K
Introduction: This study aimed to determine the dislocation and reoperation rate, functional outcomes, and the survival rate of the unique subset of very old but lucid and independent patients with hip fractures following a total hip arthroplasty (THA) and geriatric team-coordinated perioperative care. Method: Between 2000 and 2006, previously independent ambulatory patients ?80 years old presenting with an intracapsular hip fracture were given THAs under the care of an integrated orthopedic surgery–geriatric service. Their fracture-related complications, ambulation, mental status, and survival were followed for 5 to 11 years postinjury. Results: Five years postinjury, 57 (61.3%) patients of the original study group were living. In all, 3 (3.2%) patients had postoperative hip dislocations (and 2 patients had dislocation twice) and 2 reoperations were needed within the first postoperative month. There were no hip dislocations or reoperations after the first year. Radiographs obtained on 88% of the surviving patients at 5 years postoperatively showed that all remained unchanged from their immediate postoperative images. Nearly half of the patients were still able to ambulate as they did preoperatively and their mixed-model equation was statistically unchanged. Conclusion: This study of patients >80 years old with previously good functional status demonstrates that with appropriate surgical (best prosthesis, good operating technique, and regional anesthesia) and geriatric (pre- and postoperative assessments, close follow-up, medication adjustments, and fall-prevention instruction) care, they have few hip dislocations and reoperations, survive postfracture at least as long as their noninjured contemporaries, and continue to function and ambulate as they did prior to their injury.
Monzon, Daniel Godoy; Iserson, Kenneth V.; Jauregui, Jose; Musso, Carlos; Piccaluga, Francisco; Buttaro, Martin
Anterior iliopsoas impingement is a recognized cause of persistent groin pain after total hip arthroplasty. We report 3 patients with failed total hip arthroplasties resulting from anterior iliopsoas and capsular impingement secondary to a metal femoral ball with a diameter larger than the native femoral head. All patients had the same implant design. Resolution of symptoms occurred in all patients
James A. Browne; David J. Polga; Rafael J. Sierra; Robert T. Trousdale; Miguel E. Cabanela
The local hydraulic characteristics in subchannels of 5 x 5 nuclear fuel bundles with spacer grids were measured upstream and downstream of the spacer grid by using a LDV(Laser Doppler Velocimeter). THis study is focused on investigation of the spacer gri...
M. K. Chung S. K. Yang B. D. Kim K. H. Min
Experiments were performed in order to clarify the effect of grid spacers on reflood heat transfer in PWR-LOCA. The flow pattern, the thermal responses and the water accumulation near the grid spacer were investigated by shifting the grid spacer at the mi...
J. Sugimoto Y. Murao
This patent describes a spacer for use in a nuclear fuel bundle having a plurality of fuel rods. It includes spring metal spacer cells, each cell having: at least one spring leg, the spring leg inwardly deflected at the medial portion thereof for spring contact with a fuel rod within the spacer cell; at least two rod encircling arms affixed
E. B. Johansson; B. Matzner; G. M. Latter
Background The application of spacer gel represents a promising approach to reliably spare the rectal frontal wall during particle therapy (IJROBP 76:1251-1258, 2010). In order to qualify the spacer gel for the clinical use in particle therapy, a variety of measurements were performed in order to ensure the biological compatibility of the gel, its physical stability during and after the irradiation, and a proper definition of the gel in terms of the Hounsfield Unit (HU) values for the treatment planning system. The potential for the use of the spacer gel for particle therapy monitoring with off-line Positron Emission Tomography (PET) was also investigated. Results The spacer gel implanted to the prostate patient in direct neighbourhood to the clinical target volume does not interfere with the particle therapy treatment planning procedure applied at Heidelberg Ion Beam Therapy Centre (HIT). The performed measurements show that Bragg-peak position of the particles can be properly predicted on the basis of computed tomography imaging with the treatment planning system used at HIT (measured water equivalent path length of 1.011 ±0.011 (2?), measured Hounsfield Unit of 28.9 ±6.1 (2?)). The spacer gel samples remain physically unchanged after irradiation with a dose exceeding the therapeutic dose level. The independently measured Bragg-Peak position does not change within the time interval of 10 weeks. Conclusions As a result of the presented experiments, the first clinical application of spacer gel implant during prostate cancer treatment with carbon ions and protons was possible at HIT in 2012. The reported pre-clinical investigations demonstrate that use of spacer gel is safe in particle therapy in presence of therapy target motion and patient positioning induced particle range variations. The spacer gel injected between prostate and rectum enlarge the distance between both organs, which is expected to clinically significantly decrease the undesirable exposure of the most critical organ at risk, i.e. rectal frontal wall. Further research on the composition of spacer gel material might lead to additional clinical benefits by validation of particle therapy of prostate via post-therapeutic PET-imaging or by patient positioning based on the gel as a radio-opaque marker.
Inflammatory pseudotumours occasionally occur after metal-on-metal hip resurfacing and often lead to revision. Our aim was to determine the severity of this complication by assessing the outcome of revision in these circumstances and by comparing this with the outcome of other metal-on-metal hip resurfacing revisions as well as that of matched primary total hip replacements. We identified 53 hips which had undergone metal-on-metal hip resurfacing and required revision at a mean of 1.59 years (0.01 to 6.69) after operation. Of these, 16 were revised for pseudotumours, 21 for fracture and 16 for other reasons. These were matched by age, gender and diagnosis with 103 patients undergoing primary total hip replacement with the Exeter implant. At a mean follow-up of three years (0.8 to 7.2) the outcome of metal-on-metal hip resurfacing revision for pseudotumour was poor with a mean Oxford hip score of 20.9 (sd 9.3) and was significantly worse (p < 0.001) than the outcome for fracture with a mean Oxford hip score of 40.2 (sd 9.2) or that for other causes with a mean Oxford hip score of 37.8 (sd 9.4). The clinical outcome of revision for pseudotumour was also significantly worse (p < 0.001) than the outcome of matched primary total hip replacements. By contrast, the outcome for fracture and other causes was not significantly different from that of matched primary total hip replacements (p = 0.065). After revision for pseudotumour there were three cases of recurrent dislocation, three of palsy of the femoral nerve, one of stenosis of the femoral artery and two of loosening of the component. Five hips required further revision. In three of these there was evidence of recurrent pseudotumour, and one is currently awaiting further revision. The incidence of major complications after revision for pseudotumour (50%) was significantly higher (p = 0.018) than that after revision for other causes (14%). The outcome of revision for pseudotumour is poor and consideration should be given to early revision to limit the extent of the soft-tissue destruction. The outcome of resurfacing revision for other causes is good. PMID:19651827
Grammatopolous, G; Pandit, H; Kwon, Y-M; Gundle, R; McLardy-Smith, P; Beard, D J; Murray, D W; Gill, H S
Hip resurfacing arthroplasty (HRA) is a concept of hip replacement that allows treating young active patients with a femoral bone preserving procedure. The proposed advantages of resuming an active lifestyle with increased frequency and duration of sports activities have been shown to be realistic. The 30-year cost-effectiveness in young male patients has been shown to be higher in resurfacing compared to conventional total hip replacement (THA). However, prognosticators of an inferior outcome have also been identified. The most important patient related factors are secondary osteoarthritis as the indication for surgery such as post-childhood hip disorders or AVN, female gender, smaller component sizes and older age (>65 years for males and >55 years for females). In addition, surgical technique (approach and cementing technique) and component design are also important determinant factors for the risk of failure. Moreover, concerns have surfaced with respect to high metal ion concentrations and metal ion hypersensitivities. In addition, the presumed ease of revising HRA has not reflected in improved or equal survivorship in comparison to a primary THA. This highlights the importance of identifying patient-, surgery-, and implant-related prognosticators for success or failure of HRA. Rather than vilifying the concept of hip resurfacing, detailed in depth analysis should be used to specify indications and improve implant design and surgical techniques. PMID:21409754
Corten, K; Ganz, R; Simon, J P; Leunig, M
The state-of-the-art porous coatings become more and more popular in uncemented prostheses to make bone grow into implants for biological fixation. In this paper, graded cellular structures are proposed for uncemented prostheses to enhance stability on implant-bone interfaces. As an example study, the authors develop a new acetabular implant with gradient porosity for hip replacement. A gradient porous acetabular component
Hongqing Vincent Wang; Scott R. Johnston; David W. Rosen
This patent describes a nuclear reactor having fuel assemblies including an upper end fitting and a lower end fitting and spaced nuclear fuel rod spacer grids therebetween for supporting and spacing a plurality of elongated nuclear fuel rods, each of which includes a hollow active portion of nuclear fuel filled cladding intermediate the rod ends and a tapering end cap of solid materials with a circumferential groove on the rod end which first encounters reactor coolant flow, a tall spacer grid relative to the grids adjacent the active portion being means for capturing and retaining deleterious debris carried by reactor coolant before it enters the active region of a fuel assembly through solid end caps compartments' corners and creates fuel rod cladding damage.
Hatfield, S.C.; Andrews, M.G.; Broders, R.P.
The increasing popularity and success of hip arthroscopy has led to the development of related techniques for treating hip pathologies external to the joint proper. These minimally invasive endoscopic procedures serve in a diagnostic role to complement clinical evaluations and offer a therapeutic alternative to traditional open techniques. The indications for extra-articular hip endoscopy continue to expand. Recent literature describes applications for treating greater trochanteric pain syndrome, internal snapping hip, deep gluteal syndrome, and subspine impingement and for diagnosing and treating extra-articular sources of hip pain in patients who have undergone hip arthroplasty. PMID:23881610
Reich, Michael S; Shannon, Claire; Tsai, Eugene; Salata, Michael J
Labral tears in the hip may cause painful clicking or locking of the hip, reduced range of motion, and disruption to sports and daily activities. The acetabular labrum aids stabilization of the hip joint, particularly during hip motion. The fibrocartilaginous structure extends the acetabular rim and provides a suction seal around the femoroacetabular interface. Treatment options for labral tears include debridement, repair, and reconstruction. Repair of the labrum has been shown to have better results than debridement. Labral refixation is achieved with sutures anchored into the acetabular rim. The acetabular rim is trimmed either to correct pincer impingement or to provide a bleeding bed to improve healing. Labral repair has shown excellent short-term to midterm outcomes and allows patients to return to activities and sports. Arthroscopic rim trimming and labral refixation comprise an effective treatment for labral tears with an underlying diagnosis of femoroacetabular impingement and are supported by the peer-reviewed literature.
Philippon, Marc J.; Faucet, Scott C.; Briggs, Karen K.
Geriatric hip fracture is one of the commonest fractures in orthopaedic trauma. There is a trend of further increase in its incidence in the coming decades. Besides the development of techniques and implants to overcome the difficulties in fixation of osteoporosis bone, the general management of the hip fracture is also very challenging in terms of the preparation of the generally poorer pre-morbid state and complicate social problems associated with this group of patients. In order to cope with the increasing demand, our hospital started a geriatric hip fracture clinical pathway in 2007. The aim of this pathway is to provide better care for this group of patients through multidisciplinary approach. From year 2007 to 2009, we had managed 964 hip fracture patients. After the implementation of the pathway, the pre-operative and the total length of stay in acute hospital were shortened by over 5 days. Other clinical outcomes including surgical site infection, 30 days mortality and also incidence of pressure sore improved when compared to the data before the pathway. The rate of surgical site infection was 0.98%, and the 30 days mortality was 1.67% in 2009. The active participation of physiotherapists, occupational therapists as well as medical social workers also helped to formulate the discharge plan as early as the patient is admitted. In conclusion, a well-planned and executed clinical pathway for hip fracture can improve the clinical outcomes of the geriatric hip fractures.
Leung, F.; Siu, D.; Wong, G.; Luk, K. D. K.
Vertebral compression fractures (VCFs) can cause symptomatic spinal canal stenosis secondary to posterior wall retropulsion. This report describes four patients with VCF and lumbar stenosis secondary to posterior wall retropulsion who were treated with combined kyphoplasty and percutaneous interspinous spacer (IS) placement. Clinical and imaging follow-up ranged from 12-36 months. Outcomes were favorable. Combined kyphoplasty and percutaneous IS implant represents a minimally invasive, safe, and efficient option to treat VCF with symptomatic spinal stenosis. PMID:23101915
Bonaldi, Giuseppe; Cianfoni, Alessandro
Standard plasma nitriding of commercially pure Ti or various Ti alloys for human body implants (e.g., hip, knee, shoulder and ankle implants) has already proven useful. However, its use in dental implantology is rather limited due to high nitriding temperatures. The small dental implants of complex geometries are frequently distorted. To solve this problem and benefit from the ability of
C ALVESJR; C. L. B. Guerra Neto; G. H. S. Morais; C. F. da Silva; V. Hajek
The management of hip injuries in the athlete has evolved significantly in the past few years with theadvancement of arthroscopic techniques. The application of minimally invasive surgical techniques has facilitated relatively rapid returns to sporting activity in recreational and elite athletes alike. Recent advancements in both hip arthroscopy and magnetic resonance imaging have elucidated several sources of intraarticular pathology that result in chronic and disabling hip symptoms. Many of these conditions were previously unrecognized and thus, left untreated. Current indications for hip arthroscopy include management of labral tears, osteoplasty for femoroacetabular impingement, thermal capsulorrhaphy and capsular plication for subtle rotational instability and capsular laxity, lateral impact injury and chondral lesions, osteochondritis dissecans, ligamentum teres injuries, internal and external snapping hip, removal of loose bodies, synovial biopsy, subtotal synovectomy, synovial chondromatosis, infection, and certain cases of mild to moderate osteoarthritis with associated mechanical symptoms. In addition, patients with long-standing, unresolved hip joint pain and positive physical findings may benefit from arthroscopic evaluation. Patients with reproducible symptoms and physical findings that reveal limited functioning, and who have failed an adequate trial of conservative treatment will have the greatest likelihood of success after surgical intervention. Strict attention to thorough diagnostic examination, detailed imaging, and adherence to safe and reproducible surgical techniques, as described in this review, are essential for the success of this procedure.
Buly, Robert L.
Dislocations after total hip arthroplasties are one of the most common complications of the procedure. According to registers, recurrent hip dislocations account for up to 30 % of the indications for a revision operation. The incidence of a dislocation is influenced by indication-associated, patient-dependent and operation-specific risk factors. 50 % of the dislocations occur within the first 3 months which confirms the high relevance of operation-specific influencing factors. The diagnosis is almost always made with the help of computed tomography, as this is the only method to determine the three-dimensional relationship of the components. A dynamic fluoroscopic examination can verify an increased translation (reduced soft-tissue tension) and thus enables a functional examination to determine the mechanism of the dislocation. By means of a classification of dislocations into five types under consideration of the implant position, the sufficiency of the pelvitrochantar musculature, the presence of an impingement, the congruence of head and acetabular liner as well as combinations of these factors it is possible to plan an adequate therapy. From the therapeutic point of view the correct positioning of the stem and head is of decisive importance. In addition therapeutic success can be realized by using larger head diameters through to tripolar sockets, reconstruction of soft tissues and, last but not least, an adequate postoperative immobilization. Even so, this treatment is associated with a high rate of complications and in the literature failure rates of up to one third, i.e., the reoccurrence of a dislocation, are reported. PMID:22498843
Perka, C; Haschke, F; Tohtz, S
The insertion of implants and medical devices has emerged as a common and often life-saving procedure. A current estimate of the rate of total hip replacement in the world is approximately one million a year, and knee replacements more than 250000. More than 30% of hospitalized patients have one or more vascular catheters in place. More than 10% of hospitalized
J. M. Schierholz; J. Beuth
Transistors fabricated with systematic variations in Ge fraction, base doping and junction spacer width show near-ideal electrical characteristics. Emitter implantation generates anomalous boron diffusion in the base.
D J Robbins; W Y Leong; J L Glasper; A J Pidduck; R Jackson; I R C Post; Z A Shafi; P Ashburn
The metal-on-metal bearing couple is having a resurgence in clinical applications seen in total hip and hip resurfacing technologies. The most noteworthy advantage of a metal-on-metal implant is the improved wear characteristics seen in vitro on wear simulators and in vivo with retrieved implants. All bearings have disadvantages, and a metal-on-metal bearing is no exception. Concerns exist regarding the generation of metal ions seen in the blood and urine of patients with metal-on-metal implants. These elevated metal ions have theoretical, although not proven, risks related to carcinogenic and biologic concerns. Additionally, concerns exist regarding hypersensitivity, increased incidence of instability and increased costs. Specific patient selection issues arise with metal-on-metal implants. The current generation of implants has only early and mid-term results available, with no long-term series yet published. Therefore, although a metal-on-metal bearing may be considered a viable alternative to either polyethylene or ceramic implants, outstanding and unresolved issues continue to exist with this bearing, as they do with the alternatives. PMID:15577471
MacDonald, S J
We reviewed 148 consecutive hip resurfacings in order to assess the clinical outcomes of the BHR at midterm follow-up and to compare the accuracy of the navigation in the positioning of femoral component. We retrospectively analyzed 85 hips using the conventional jig to implant the femoral component and we prospectively followed 63 hips operated on by navigation. At a mean follow-up of 50.54 months, the Harris hip score improved significantly from 44.66 preoperatively to 98.45 postoperatively without any differences between the groups. Radiologically, we classic navigated group. Our clinical outcomes are excellent at midterm follow-up and the navigation definitely improves the implant position in both planes. PMID:24140277
El Hachmi, Mohamed; Penasse, Michel
The issue of utilizing a temporary cement spacer after a knee resection arthrodesis of a highly malignant bone tumor is discussed. In our experience, this is the first type of reconstruction performed in the early days of the limb salvage. Now, after more than 12 years of follow-up based on the results of 84 patients, the usefulness and mechanical performance of this type of reconstruction are considered. Of these patients, 45 died of disease. Wound complications were present in 31% of the patients and led to amputation in 7 and healing failure in 6. Mechanical complications occurred in 39%, but radiographic analysis of the implant showed 32 cases (38%) with an inadequate spacer. Only 9 patients are still walking on the original reconstruction, 6 of them uncomplicated (the remaining 3 had rod migrations and shortening). The survival curve showed no statistical difference between the two groups (adequate vs inadequate spacer). In 33 patients who are still alive and retain their limb, the final functional results were excellent in 6, good in 8, fair in 14, and poor in 5. This type of reconstruction can still be considered in developing countries, or when a definitive arthrodesis is planned where there is a lack of a bone source (children, no bone bank). In our institution, reconstruction with cement is still suggested for patients with a large tumor around the knee, when the quadriceps is completely sacrificed, and the patient prognosis is markedly unfavorable. PMID:11880918
Donati, D; Giacomini, S; Gozzi, E; Sorin, E; Borz, S; Mercuri, M; Bacci, G
Of a total of 818 limb sparing resections in the lower limb requiring reconstruction between December 2002 and April 2010 at our centre, primary cement spacers were used in 15 cases. In three cases they were used as joint sparing intercalary reconstructions and in 12 cases knee arthrodesis was done. Implants used to provide stability to the construct included stacked intramedullary Kuntscher nails in four, an interlocking nail in one, plates in two and a combination of nail with plate in eight. Mean length of bone resected was 18 cm. Mean follow-up was 26 months (10-87 months). There were no local recurrences and none of the spacers needed revision for mechanical failure. The Musculoskeletal Tumor Society score for patients ranged from 20 to 29 with a mean of 24 (80%). Patients with intercalary resection had better functional scores than those with arthrodesis. The construct was successfully revised to a vascularised fibula arthrodesis or prosthesis with good eventual function in three cases. Cement spacers are a suitable cost-effective, durable reconstruction modality in selected patients with good functional outcomes. They are an option to amputation in patients with financial constraints and those that present with large volume or infected fungating tumors. PMID:21775149
Puri, Ajay; Gulia, Ashish; Pruthi, Manish; Koushik, S
Metal-on-metal (MoM) hip bearings are being inserted into ever-younger patients. The effects on the immune system of chronic exposure are unknown. We investigated the immune response of patients with MoM hip bearings. In patients with MoM implants, the expression of antigen-presenting cell (APC) surface molecules (CD86 and HLA-DR) was seen to be significantly higher (P < .05) than control group.
Paul M. Whittingham-Jones; Edward Dunstan; Huwaidha Altaf; Stephen R. Cannon; Peter A. Revell; Timothy W. R. Briggs
An anatomical hip model has been developed to simulate the impact load on the hip of a falling person wearing a hip protector. The hip consists of an artificial pelvis made of aluminium, linked by a ball-and-socket joint to an anatomically shaped steel femur (thigh bone). The femur is embedded in silicone material with a hip-shaped surface to allow realistic positioning of the protectors with accessory underwear. Additionally, the silicone simulates the damping and load-dispersal effect of soft tissue. A triaxial load sensor is integrated in the neck of the femur to measure the axial and cross-sectional force components in response to external impact forces on the hip. The performance of the hip model was investigated in drop tests and validated against biomechanical data. In a first series of measurements, the shock absorption of 10 different hip protectors, including both energy-absorbing and energy-shunting systems, was analysed. To determine the importance of hip protector placement, each protector was tested in the correct anatomical alignment over the hip and anteriorly displaced by 3 cm. Considerable differences were found between individual hip protectors in their effectiveness to reduce impact forces on the femur. Position of the hip protector also influenced the forces applied to the femur. PMID:15990064
Derler, Siegfried; Spierings, A B; Schmitt, K-U
...Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis. ...Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis. ...hip joint femoral (hemi-hip) metal/polymer cemented or uncemented...
The goal of this study was to determine whether obesity affects implant positioning or early functional outcome after minimally invasive total hip replacement. The authors evaluated 119 patients who had undergone minimally invasive total hip replacement via a direct anterior approach. The patients were segregated according to World Health Organization body mass index categories: nonobese, overweight, or obese. Perioperative variables, resulting cup position, and early outcome (Harris Hip Score) were assessed. The only significant difference among the groups was mean operative time (obese > overweight > nonobese). Although the obese group's 2-year Harris Hip Score was the lowest, all patients had good to excellent results. In conclusion, minimally invasive hip replacement in obese patients provides early outcomes comparable to those in nonobese patients. PMID:24875336
Hungerford, Marc W; Schuh, Reinhard; O'Reilly, Michael P; Jones, Lynne C
Total hip replacement has seen a tremendous development and has become one of the most successful surgical interventions in orthopaedics. While during the first decades of development of total hip arthroplasty the fixation of the implant into the bone was the main concern, the focus has shifted towards surgical technique and soft tissue handling. In order to avoid permanent soft tissue damage, muscular dysfunction and concerns in regards to cosmetics, minimal invasive and anatomic approaches have been developed. We here provide a short overview on various methods of total hip replacements and we describe our technique through a minimal invasive direct anterior approach. While muscle and nerve damage is minimal, this technique allows for a rapid rehabilitation and is associated with an excellent functional outcome and a minimal risk for dislocation. PMID:23346746
Moerenhout, Kevin G; Cherix, Stéphane; Rüdiger, Hannes A
Coxa saltans or snapping hip, in its internal and external varieties, is a well-known syndrome in the coxofemoral orthopedic pathology. The internal variety is less frequent and is rather unusual after a total hip arthroplasty (THA). This disorder is often times mistaken with chronic groin pain after a THA. This paper describes a typical case of snapping hip in the setting of THA and helps recognize the clinical differences between both entities, with a description of the signs and symptoms that characterize them. In order to support the etiology and pathogenesis, the diagnosis and treatment, we include anatomical considerations concerning the variants of the iliopsoas musculo-tendinous complex attachment, its relations with the articular capsule and the iliopectineal bursa. The role of implant malpositioning in this entity is reviewed and the usefulness of various diagnostic and treatment methods is discussed. PMID:20377060
Gómez García, Felipe
The aim of this review is to evaluate the current available literature evidencing on peri-articular hip endoscopy (the third compartment). A comprehensive approach has been set on reports dealing with endoscopic surgery for recalcitrant trochanteric bursitis, snapping hip (or coxa-saltans; external and internal), gluteus medius and minimus tears and endoscopy (or arthroscopy) after total hip arthroplasty. This information can be used to trigger further research, innovation and education in extra-articular hip endoscopy.
Verhelst, L.; Guevara, V.; De Schepper, J.; Van Melkebeek, J.; Pattyn, C.; Audenaert, E. A.
Total hip arthroplasty (THA) is considered one of the most successful surgical procedures in orthopaedics. With the increase in the number of THAs performed in the world in the next decades, reducing or preventing medical and mechanical complications such as post-operative THA instability will be of paramount importance, particularly in an emerging health care environment based on quality control and patient outcome. Dual mobility acetabular component (also known as unconstrained tripolar implant) was introduced in France at the end of the 1970s as an alternative to standard sockets, to reduce the risk of THA dislocation in patients undergoing primary THA in France. Dual mobility cups have recently gained wider attention in the United States as an alternative option in the prevention and treatment of instability in both primary and revision THA and offer the benefit of increased stability without compromising clinical outcomes and implant longevity. In this article, we review the use of dual mobility cup in total hip arthroplasty in terms of its history, biomechanics, outcomes and complications based on more than 20 years of medical literature.
De Martino, Ivan; Triantafyllopoulos, Georgios Konstantinos; Sculco, Peter Keyes; Sculco, Thomas Peter
Implantation of a cementless press-fit acetabular cup during hip arthroplasty alters stress transfer to the periacetabular bone, resulting in stress shielding of cancellous bone and enhanced load transfer to cortical bone. Theoretically, the thicker, stiffer and larger acetabular cup of a hip resurfacing may increase periacetabular bone stress shielding. We attempted to assess the matter (at a minimum of 2 years after surgery) by measuring any difference in supra acetabular bone mineral density (BMD) between the side implanted with a thick monoblock cobalt-chromium (Co-Cr) acetabular component during hip resurfacing (HR) and the opposite non-operated side. We retrospectively recruited 44 patients who had undergone metal-on-metal hybrid hip resurfacing for unilateral osteoarthritis of the hip joint . BMD of the supra acetabular bone of both hips was measured using a dual energy X-ray absorptiometry (DEXA) scan. The BMD measured in Zone 2 was not different on the operated side (1.69 g/cm2 ± 0.48) compared with the non-operated side (1.70 g/cm2 ±0.49) (p=0.904). Contrary to our expectations, implantation of a monoblock Co-Cr acetabular component during HR did not cause significant stress-shielding of supra acetabular cancellous bone. PMID:21818746
Yahia, Chabane Ait; Diwanji, Sanket; Ganapati, Muthu; Vendittoli, Pascal-André; Lavigne, Martin
Background Severe acetabular deficiencies in cases of developmental dysplasia of the hip (DDH) often require complex reconstructive procedures in total hip arthroplasty (THA). The use of autologous femoral head grafts for acetabular reconstruction has been described, but few data is available about clinical results, the rates of non-union or aseptic loosening of acetabular components. Methods In a retrospective approach, 101 patients with 118 THA requiring autologous femoral head grafts to the acetabulum because of DDH were included. Six patients had died, another 6 were lost to follow-up, and 104 hips were available for clinical and radiological evaluation at a mean of 68 ± 15 (13 to 159) months. Results The average Merle d'Aubigné hip score improved from 9 to 16 points. Seven implants had to be revised due to aseptic loosening (6.7%). The revisions were performed 90 ± 34 (56 to 159) months after implantation. The other hips showed a stable position of the sockets without any signs of bony non-union, severe radiolucencies at the implant-graft interface or significant resorption of the graft. Conclusion The use of autologous femoral head grafts with cementless cups in primary THA can achieve promising short- to midterm results in patients with dysplastic hips.
A spacer for fuel rods assembled into a fuel assembly for nuclear reactors is formed of a grid structure of sheetmetal webs passing edgewise perpendicularly through one another including resilient and rigid contact elements fastened to the sheetmetal webs. Each of the fuel rods is supportable by two diagonally opposing three-point contact systems, each of the systems being formed of one of the resilient contact elements and two of the rigid contact elements, the one resilient contact element being centrally disposed, as viewed in axial direction, and the two rigid contact elements being oppositely disposed and being ringshaped.
A grid spacer for use in a nuclear fuel assembly for holding the fuel rods in relatively fixed positions is described comprising strips intersecting each other to form cells, through which the fuel rods will extend; springs on the grid strips positioned in the cells so as to engage the fuel rods; and a peripheral strip secured at the ends of the grid strips. The grid strips having the edges which will be upstream relative to the flow of cooling fluid when mounted in the reactor being convexly contoured.
King, P.P.; Patterson, J.F.; Yates, J.; Brown, C.A.
Aseptic loosening is one of the commonest complications of total hip replacement that can cause pain and instability. The chronic inflammatory response to the wear debris from the polyethylene or metal can cause osteolysis and implant failure. We report a case of aseptic loosening of the hip, presented with a swelling over the anterior thigh without any pain or instability in the joint. This mass was a foreign body granuloma formed secondary to the polyethylene wear debris due to the instability of the polyethylene in the metal shell. The patient underwent successful revision hip arthroplasty after the removal of the foreign body granuloma. PMID:21984313
Gudena, Ravindra; Kuna, Suma; Pradhan, Nikhil
Introduction Metal-on-metal bearings for total hip arthroplasty are increasing in popularity. However, metal ion toxicity, metal hypersensitivity,\\u000a and metal carcinogenicity are the causes concern for patients with metal-on-metal hip replacement. We investigated serum levels\\u000a of cobalt and chromium ions in patients with successfully implanted second-generation metal-on-metal total hip arthroplasty\\u000a (THA) using PINNACLE-A (DePuy, Warsaw, IN, USA).\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods Thirty-three patients underwent
Takao Imanishi; Masahiro Hasegawa; Akihiro Sudo
A 68-year-old man with a previous right total hip arthroplasty presented with acute pain in the right hip, and no associated trauma was reported. The previous hybrid arthroplasty consisted of a ceramic femoral head articulating on an ultra-high-molecular-weight polyethylene liner. The unusual diagnosis of fractured ceramic femoral head was made and an urgent revision arthroplasty was performed to remove the ceramic bearing as well as all implants that may have come into contact with the ceramic. This case report highlights the material properties of ceramics in total hip arthroplasties as well as the importance of regular follow-up in these patients. PMID:24515234
Tucker, Damien; Acharya, Mehool
... this Page How big is the problem? What outcomes are linked to hip fractures? Who is at risk? How can hip fractures be prevented? References Hip fractures are serious fall injuries that often result in long-term functional impairment, nursing home admission and increased mortality. 1,2 As ...
Hip pain is a common condition, and the work-up often includes imaging. This article reviews the normal MR anatomy of the hip and the imaging findings of internal derangements, snapping hip, and femoral acetabular impingement. We will describe the role of MR arthrography in evaluating the patient with suspected labral and articular cartilage abnormalities, as well as the pitfalls in
Donna G. Blankenbaker; Michael J. Tuite
The British Thoracic Society and Scottish Intercollegiate Guidelines Network recommend that children up to the age of five should use a pressurised metered dose inhaler with a spacer device to deliver inhaled steroids. However, large-volume spacers can be cumbersome, which is why I designed a smaller, more portable device to encourage spacer use. After prototypes were made, the idea was presented to the local NHS innovations department. With its advice and assistance, a collapsible spacer device has been developed. This article describes the product development process. PMID:23495581
Metal implants corrode and release metal ions, cobalt and chromium, which, in turn, may cause systemic toxicity, mostly in the first few months from implantation of metal-on-metal hip arthroplasty. At the time of delivery, the placenta reduces the passage of cobalt and chromium ions released from metal-on-metal prosthesis. From a biomechanical view point, hip replacement should not be considered a contraindication for pregnancy or for spontaneous delivery, and does not seem to have any negative effects in terms of risk of dislocation, loosening, fracture, or revision surgery, neither negative effects on clinical and functional outcomes. The long-term biological consequences of exposure to Co-Cr particles and ions remain largely unknown. PMID:22105045
Maffulli, Nicola; Del Buono, Angelo; Denaro, Vincenzo
Background A variety of femoral stem designs have been reported to be successful in revision total hip arthroplasty without consensus as to optimal design. We evaluated the clinical and radiographic outcomes in a consecutive series of femoral revisions using a wedge-shape, tapered-stem design at medium and long-term follow-up. Materials and methods We performed a retrospective review of clinical and radiographic outcomes of twenty-eight consecutive femoral revisions arthroplasties, which were done using the Zweymuller femoral stem. Results The mean follow-up was 7.4 years (range 2–15 years). No stem re-revision was necessary. All stems were judged to be stable by radiographic criteria at the most recent follow-up. The final mean Harris hip score was 90. There was no difference in Harris hip scores, implant stability, or radiological appearance (distal cortical hypertrophy or proximal stress shielding) of the implants between medium-term (mean 5.7 years) and long-term (mean 12.4 years) follow-up. Conclusions We found the Zweymuller femoral stem design to be durable for revision hip arthroplasty when there is an intact metaphyseal-diaphyseal junction for adequate press-fit stability at surgery.
Huo, Michael H.; Keggi, Kristaps J.
A modular grid welding fixture for a spacer grid that facilitates full grid laser welding of a spacer grid in one setup is disclosed. The modular design allows for partial implementation of each weld type. A base plate is used for mounting to the positioning/rotational plate of the welding system. A removable sub-plate received in the base plate is used to position the grid strips for proper location for welding. A top fixture plate is aligned with the base plate and provides for mounting of a second sub-plate if required. Side plates with spring loaded pressure pads that are hinged to the top fixture plate apply uniform pressure to the outer grid strips during processing. The base plate, top plate, side plate, and pressure pads are provided with a plurality of through holes to allow access of the laser beam for welding. Corner clips are used to insure contact of the overlapping sections of the outer grid strips for proper corner welding. 4 figs.
Anderson, M.W.; Whitt, J.S.
In the patient with lateral hip pain, there is a broad differential diagnosis, making appropriate evaluation and management challenging. Greater trochanteric pain syndrome is a term used to denote chronic lateral hip pain and encompasses several painful soft tissue diagnoses including coxa saltans, trochanteric bursitis, and gluteus minimus and medius tendon tears. An overview of these common causes is presented through a series of cases that encompass the anatomic associations, classic presentations, diagnostic tests, and management strategies unique to each disorder. By reviewing this information, we hope to provide clinicians with the tools to evaluate greater trochanteric pain syndrome efficiently and effectively. PMID:24651142
Kimpel, Diane M; Garner, Chadwick C; Magone, Kevin M; May, Jedediah H; Lawless, Matthew W
Imaging studies are central to the evaluation of persistent or recurrent symptoms after hip arthroplasty. The evaluation starts with radiographs and may be followed by arthrography, aspiration, scintigraphy, sonography, computed tomography, and MR imaging. Common etiologies of a painful or dysfunctional hip arthroplasty are mechanical loosening, polyethylene wear-induced osteolysis, adverse local tissue reaction to metal wear products, infection, fractures, heterotopic ossification, tendinopathy, and nerve injury. MR imaging with optimized protocols and dedicated techniques for metal artifact reduction is the most comprehensive imaging modality. In this article, we discuss and illustrate the imaging appearances of these conditions with a focus on the MR imaging evaluation. PMID:23787986
Fritz, Jan; Lurie, Brett; Miller, Theodore T
We present our experience over 6 years with the use of uncemented total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH) with a mean follow-up of 3 years. In a 6-year period, 26 THAs were performed in 19 patients with Hartofilakidis grades 2 and 3 dislocation of the hips. Out of 19 patients, seven had bilateral dislocations. Uncemented
Rehan Gul; Eric Masterson
OBJECTIVES: This paper proposes imaging with 3-dimensional vibroacoustography for postoperatively assessing the uncovered cup area after total hip arthroplasty as a quantitative criterion to evaluate implant fixation. METHODS: A phantom with a bone-like structure covered by a tissue-mimicking material was used to simulate a total hip arthroplasty case. Vibroacoustography images of the uncovered cup region were generated using a two-element confocal ultrasound transducer and a hydrophone inside a water tank. Topological correction based on the geometry of the implant was performed to generate a 3-dimensional representation of the vibroacoustography image and to accurately evaluate the surface. The 3-dimensional area obtained by the vibroacoustography approach was compared to the area evaluated by a 3-dimensional motion capture system. RESULTS: The vibroacoustography technique provided high-resolution, high-contrast, and speckle-free images with less sensitivity to the beam incidence. Using a 3-dimensional-topology correction of the image, we accurately estimated the uncovered area of the implant with a relative error of 8.1% in comparison with the motion capture system measurements. CONCLUSION: Measurement of the cup coverage after total hip arthroplasty has not been well established; however, the covered surface area of the acetabular component is one of the most important prognostic factors. The preliminary results of this study show that vibroacoustography is a 3-dimensional approach that can be used to postoperatively evaluate total hip arthroplasty. The favorable results also provide an impetus for exploring vibroacoustography in other bone or implant surface imaging applications.
Kamimura, Hermes A. S.; Wang, Liao; Carneiro, Antonio A. O.; Kinnick, Randall R.; An, Kai-Nan; Fatemi, Mostafa
Hypersensitivity to metals and tissue reaction around a failed implant were investigated in 40 patients undergoing revision\\u000a hip arthroplasty. Metal sensitivity was tested using a standard cutaneous patch test. Nine patients were positive for chromium,\\u000a nickel, cobalt, metal rust or endoprosthesis scrapings, or combinations of these allergens. Patients with positive or negative\\u000a patch test did not differ in terms of
V. Milavec-Pureti?; D. Orli?; A. Maruši?
Infection is a frequent cause of failure after joint replacement surgery. The infection rate after total hip arthroplasty (THA) has been reduced to 1-2% in the last years. However, it still represents a challenging problem for the orthopedic surgeon. Difficulty of therapeutic approach, and poor functional outcomes together with length of treatment and overall cost are the main burden of this issue. Even the diagnosis of an infected hip could be challenging although it is the first step of an accurate treatment. At the end, many cases require removing the implants. Afterwards, the treatment strategy varies according to authors with three different procedures: no re-implantation, immediate placement of new implants or a two-stage surgery re-implantation. Based on the most recently systematic review there is no suggestion that one- or two-stage revision methods have different re-infection outcomes. The two-stage implant-exchange protocol remains the gold standard. It is considered as the most efficacious clinical approach for the treatment of periprosthetic infection, especially in patients with sinus tracts, swelling, extended abscess formation in depth and infection of Methicillin Resistant Staphylococcus Aureus (MRSA), and other multidrug-resistant bacteria as reported in recent consensus documents.
Cherubino, Paolo; Puricelli, Marco; D'Angelo, Fabio
A case is presented illustrating the potential effect of Brennan Healing Science on pain following hip arthroplasty for avascular necrosis. A 54-year-old woman experienced anterior groin pain, numbness at the bottom of her foot, and occasional grinding at her hip 22 years after right total hip arthroplasty secondary to avascular necrosis. X-ray films showed signs of osteolysis behind the acetabular cup and asymmetric decreased polyethylene thickness of the acetabular prosthetic. Her orthopedic surgeon advised the patient to follow up every 6-9 months to avoid catastrophic failure of the implant, with plans for surgical revision to be scheduled at the next appointment. The patient sought alternative treatment to avoid an invasive procedure. On presentation, the patient had difficulty walking up the stairs into the treatment room due to pain which she rated a 9/10. She found it painful to rotate, flex, extend her hip, or to sit. Hands-on healing techniques based on the Brennan Healing Science method were initiated, starting at the feet, balancing the energy, and working the way up the joints. Once the work at the hip was completed, the hands-on techniques continued up the centerline of the body and the healing was brought to a close. On completion of a 60-minute healing, the patient was able to stand freely and rated her pain as a 4/10. Flexion, extension, and rotation at the hip were no longer distressing. She was able to walk up and down stairs without distress and denied instability, bursitis, or trochanteric or iliopsoas pain or swelling. Repeat X-rays showed decrease in bone spurs and no hardware problem, and her orthopedic surgeon recommended follow-up after 2 years. It is suggested that Brennan Healing Science techniques could play an effective and cost-efficient role in the treatment of pain following hip arthroplasty. PMID:24439097
This report examines the clinical performance of three very similar total hip arthroplasty designs with distinctly different bearing surfaces used over the course 10-17 years. Clinical outcomes assessments for each group are compared in the context of varying implant related costs related to the latest technology at the time of surgery. Eighty-one surgeries were studied and differ by bearing surface. In this study, 36 hips are ceramic on polyethylene, 27 are metal on polyethylene and 18 are metal on metal. All polyethylene components are nonhighly cross-linked. The ceramic on polyethylene group has younger patients, on average, and higher percentage of patients with significant polyethylene wear. These groups have an average follow-up time of 8.6 years when assessing functional hip scores, thigh pain, groin pain, revision surgeries and radiographic osteolysis. The implant purchasing cost at the time of surgery was assessed to determine if a correlation exists between outcomes and the more technologically advanced implants use at the time of surgery. Based on midterm clinical outcome assessment, no correlation between initial hospital cost and clinical outcomes of one bearing surface over another can be found. PMID:25002938
Parsons, Christopher; Batson, Ryan; Reighard, Shane; Tanner, Stephanie; Snider, Becky; Pace, Thomas B
This report examines the clinical performance of three very similar total hip arthroplasty designs with distinctly different bearing surfaces used over the course 10-17 years. Clinical outcomes assessments for each group are compared in the context of varying implant related costs related to the latest technology at the time of surgery. Eighty-one surgeries were studied and differ by bearing surface. In this study, 36 hips are ceramic on polyethylene, 27 are metal on polyethylene and 18 are metal on metal. All polyethylene components are nonhighly cross-linked. The ceramic on polyethylene group has younger patients, on average, and higher percentage of patients with significant polyethylene wear. These groups have an average follow-up time of 8.6 years when assessing functional hip scores, thigh pain, groin pain, revision surgeries and radiographic osteolysis. The implant purchasing cost at the time of surgery was assessed to determine if a correlation exists between outcomes and the more technologically advanced implants use at the time of surgery. Based on midterm clinical outcome assessment, no correlation between initial hospital cost and clinical outcomes of one bearing surface over another can be found.
Parsons, Christopher; Batson, Ryan; Reighard, Shane; Tanner, Stephanie; Snider, Becky; Pace, Thomas B.
Background Evolvements in the design, fixation methods, size, and bearing surface of implants for total hip replacement (THR) have led to a variety of options for healthcare professionals to consider. The need to determine the most optimal combinations of THR implant is warranted. This systematic review evaluated the clinical effectiveness of different types of THR used for the treatment of end stage arthritis of the hip. Methods A comprehensive literature search was undertaken in major health databases. Randomised controlled trials (RCTs) and systematic reviews published from 2008 onwards comparing different types of primary THR in patients with end stage arthritis of the hip were included. Results Fourteen RCTs and five systematic reviews were included. Patients experienced significant post-THR improvements in Harris Hip scores, but this did not differ between impact types. There was a reduced risk of implant dislocation after receiving a larger femoral head size (36 mm vs. 28 mm; RR?=?0.17, 95% CI: 0.04, 0.78) or cemented cup (vs. cementless cup; pooled odds ratio: 0.34, 95% CI: 0.13, 0.89). Recipients of cross-linked vs. conventional polyethylene cup liners experienced reduced femoral head penetration and revision. There was no impact of femoral stem fixation and cup shell design on implant survival rates. Evidence on mortality and complications (aseptic loosening, femoral fracture) was inconclusive. Conclusions The majority of evidence was inconclusive due to poor reporting, missing data, or uncertainty in treatment estimates. The findings warrant cautious interpretation given the risk of bias (blinding, attrition), methodological limitations (small sample size, low event counts, short follow-up), and poor reporting. Long-term pragmatic RCTs are needed to allow for more definitive conclusions. Authors are encouraged to specify the minimal clinically important difference and power calculation for their primary outcome(s) as well CONSORT, PRISMA and STROBE guidelines to ensure better reporting and more reliable production and assessment of evidence.
Tsertsvadze, Alexander; Grove, Amy; Freeman, Karoline; Court, Rachel; Johnson, Samantha; Connock, Martin; Clarke, Aileen; Sutcliffe, Paul
One hundred seventy-one primary total hip arthroplasties were evaluated in a prospective, randomized study. Ninety-five involved a metal-backed cup with an all-metal liner and 76 involved a metal-backed polyethylene cup that was used as the control. All were implanted with an S-ROM cementless femoral component with a 28 mm head. The mean follow-up period was 3.7 years (range, 3.0–5.7). The
Michael Jacobs; Robert Gorab; David Mattingly; Lorence Trick; Carleton Southworth
The 2 main null hypotheses of this study were: (1) the 4-year surgical trauma-related degeneration within the hip abductor muscles after a minimally invasive approach to total hip arthroplasty would be similar to that following a conventional approach; and (2) no differences in perioperative blood loss or postoperative hip pain would be observed between the minimally invasive and conventional approaches.In 40 consecutive randomly selected adult patients with unilateral primary hip osteoarthritis, a cementless Zweymüller-Plus THA (Smith & Nephew Orthopaedics, Baar, Switzerland) was implanted by a single surgeon in 1 institution during the same period. Twenty patients underwent a minimally invasive approach (group A), and 20 patients underwent a conventional anterolateral approach (group B). Four years postoperatively, the operated and contralateral nonoperated hips of 37 available patients from both groups were examined with magnetic resonance imaging to show any changes in the gluteus medius and tensor fascia latae. Simultaneously, hip abductor power was measured bilaterally in both groups. Anthropometric data, blood loss, Short Form 36 self-assessment questionnaire, visual analog pain score, and walking distance were also analyzed.The reliability of magnetic resonance imaging and hip abductor power measurements was high. No difference was found in hip abductor power on the operated side between the 2 groups, whereas hip abductor power on the nonoperated side was significantly higher in both groups. This study revealed no mechanical and functional benefits in favor of patients undergoing minimally invasive vs conventional total hip arthroplasty. PMID:23218622
Vasilakis, Ioannis; Solomou, Ekaterini; Vitsas, Vasilis; Fennema, Peter; Korovessis, Panagiotis; Siamblis, Dimitrios K
Background Periprosthetic joint infections (PJI) are often treated by two stage exchange with the use of an antibiotic impregnated spacer. Most of the two-stage exchange algorithms recommend the implantation of an antibiotic-impregnated spacer during the first stage for a period of 2–24 weeks before reimplantation of the new prosthesis. For the spacer to have a therapeutic effect, the local antibiotic concentration must be greater than the minimal inhibition concentration (MIC) against the pathogens causing the PJI. It must remain so for the entire spacer period, otherwise recurrence of infection or resistances might occur. The question as to whether a sufficient concentration of antibiotics in vivo is reached for the entire spacer period has not been answered satisfactorily. Case presentation We here present a case of a histologically confirmed chronic PJI 20 month after primary arthroplasty. The primary knee arthroplasty was performed due to osteoarthritis of the joint. Initial assessment did not detect a causative pathogen, and two stage exchange with a vancomycin-gentamycin impregnated spacer was performed. At the time of reimplantation, sonication of the explanted spacer revealed a multi-resistant strain of staphylococcus epidermidis on the device and in the joint. Adaption of the therapy and prolonged treatment successfully eradicated the infection. Conclusion According to the authors’ knowledge, the case presented here confirms for the first time the surface contamination (proven through sonication) of a vancomycin-/gentamicin- impregnated Vancogenx®-spacer with a MRSE after ten weeks of implantation. This case study demonstrates the difficulties still associated with the diagnostics of PJI and the published different two stage treatment regimes with the use of antibiotic impregnated spacers.
The aim of this study was to evaluate the outcomes of reduction in the treatment of traumatic posterior hip dislocation in children. Data of 22 pediatric patients (22 hips) with traumatic hip dislocation from January 1995 to December 2007 were analyzed. The clinical evaluation focused on symptoms, physical findings, and range of motion. Radiographs identified the type of hip dislocation. The hip dislocation classification was based on Thompson and Epstein. The reduction procedure was performed according to three variants: variant 1, closed reduction; variant 2, release of the adductor longus, lengthening of the psoas tendon, and insertion of a Kirschner wire through the femoral head into the acetabulum; and variant 3, removal of the soft-tissue interposition of the hip. After reduction, radiography was used to determine whether the hip is concentric and to check whether any other injuries might have been caused after manipulation. There were six females (27.3%) and 16 males (72.7%) in this study. All had type I posterior dislocation of the hip. The ages of the patients at diagnosis ranged from 3 years, 2 months to 9 years, 10 months. The reduction procedure was performed according to variant 1 in 16, variant 2 in five, and variant 3 in one. We attained excellent results in eight hips (36.4%), good results in seven hips (31.8%), fair results in four hips (18.2%), and poor results in three hips (13.6%). There was avascular necrosis in three hips (13.6%), coxa magna in two hips (9.1%), deficient limb of 2 cm in two hips (9.1%), and a limp in two hips (9.1%). The hip scores were 82.4 points on average (range 62-100). Children with traumatic hip dislocation should undergo reduction as soon as possible. If the interval from injury to reduction exceeds 3 weeks, we suggest that the surgeon release the adductor longus, lengthen the psoas tendon, and insert a Kirschner wire. This simple and safe surgical procedure results in marked improvement in hip function and prevents complications later. PMID:22751480
Hung, Nguyen Ngoc
Background and purpose Total hip arthroplasties in young patients have lower long-term survival rates than in older patients. We evaluated the use of a unique treatment protocol in patients aged between 40 and 50 years. In all cases we used a cemented THA, and for acetabular deficiencies we also used impacted bone grafts together with a cemented cup. Methods In 140 consecutive patients who were between 40 and 50 years of age at index surgery, 168 cemented total hip prostheses were evaluated after a mean follow-up time of 10 (2–19) years. Acetabular deficiencies were reconstructed with wire meshes and impacted bone grafts with a cemented cup (70 hips). During follow-up, 18 patients died (27 hips); in this group 3 hips (3 patients) had been revised. None of the patients were lost to follow-up. In all surviving patients, clinical assessment was performed with hip-score questions and all radiographs were evaluated. Results All clinical questionnaires showed an improved clinical hip score. 29 hips (17%) were revised after a mean of 8 (0.3–18) years. Kaplan-Meier survival analysis showed a survival of 88% (95% CI: 82–94) after 10 years with revision of either component for any reason. Survival with endpoint revision for aseptic loosening of either component was 94% (95% CI: 90–99) after 10 years. Interpretation Cemented implants in young patients have satisfying long-term results. Reconstruction of acetabular deficiencies with impacted bone grafts show promising results.
de Kam, Daniel C J; Gardeniers, Jean W M; Veth, Rene P H
This paper presents a powerful new design aspect to reduce acoustic noise and vibration of electro-magnetic origin for electrical machines, by introducing improved slot wedges referred to as “structural stator spacers”. These spacers, by using a very stiff dielectric and nonmagnetic material, a modified shape and small modifications to the stator laminations not only secure the windings and reduce windage
P. O. Rasmussen; J. Andreasen; J. M. Pijanowski
A new technique of model surgery using LEGO plates as key-spacers is described. This technique requires less time to set up compared with the conventional plaster model method. It also retains the preoperative setup with the same set of models. Movement of the segments can be measured and examined in detail with LEGO key-spacers. PMID:24045189
Tsang, Alfred Chee-Ching; Lee, Alfred Siu Hong; Li, Wai Keung
We studied the mask defect printability for both opaque and clear defects in the spacer patterning process. The spacer patterning process consists of the development of photoresist film, the etching of the core film using the photoresist pattern as the etching mask, the deposition of a spacer film on both sides of the core film pattern, and the removal of the core film. The pattern pitch of the spacer film becomes half that of the photoresist. The opaque defect and the clear defect of the mask, respectively, resulted in an "open-short complex" defect and a short defect in the spacer pattern, The defect size of both the opaque and clear defect became smaller as the process proceeded from the development to the core film etching and the spacer pattern fabrication. The decrease of the mask defect printability during the spacer process is likely to be related to the reduction of the line width roughness (LWR) and to the reduction of mask enhanced factor (MEF). The acceptable mask defect size was also studied from the viewpoint of the defect printability to the spacer pattern for both the opaque and clear defect, and found to be 55-60nm, which was relaxed from that in ITRS2007.
Miyoshi, Seiro; Yamaguchi, Shinji; Hirano, Takashi; Mashita, Hiromitsu; Mukai, Hidefumi; Kobiki, Ayumi; Kobayashi, Yuuji; Hashimoto, Kohji; Inoue, Soichi
Recently, much attention has been focused on the design of the fuel assemblies in the Pressurized Light Water Reactor (PLWR). The spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water, and maintains geometry from the external impact loads. In this research, a new shape of the spacer grid is
K. N. Song; K. H. Yoon; B. S. Kang; G. J. Park; S. K. Choi
Recently, much attention is focused on the design of fuel assemblies in the Pressurized Light Water Reactor (PWR). The spacer grid is one of the main structural components in a fuel assembly. It supports fuel rods, guides cooling water, and maintains geometry from external impact loads. In this research, a new shape of the spacer grid is designed by axiomatic
Ki-Jong PARK; Byung-Soo KANG; Kee-Nam SONG; Gyung-Jin PARK
Hip pain is a common complaint with many causes. Pathology in the hip can present with pain referred to sites other than the hip and pain in the hip may result from pathology elsewhere. An accurate history and examination is paramount. Chronic painful conditions of the hip summarised in this paper can be classified into three main groups: intra-articular, extra-articular
Olivia Flannery; Connor Green; Dominic Harmon; Eric Masterson
...2010-04-01 false Hip joint (hemi-hip) acetabular metal cemented prosthesis. 888...888.3370 Hip joint (hemi-hip) acetabular metal cemented prosthesis. (a...Identification. A hip joint (hemi-hip) acetabular metal cemented prosthesis is a...
...2009-04-01 false Hip joint (hemi-hip) acetabular metal cemented prosthesis. 888...888.3370 Hip joint (hemi-hip) acetabular metal cemented prosthesis. (a...Identification. A hip joint (hemi-hip) acetabular metal cemented prosthesis is a...
We determined the nucleotide sequence of a D. melanogaster ribosomal DNA spacer. Sequences of various portions of different cloned ribosomal spacers have been previously reported. We extend the analysis to cover the entire nontranscribed and external transcribed regions. Comparison to other cloned ribosomal DNA gene units of this species confirms a conserved general organization of the ribosomal spacer through different size classes. D. melanogaster ribosomal gene units interrupted by insertions are known to be transcribed at a much lower level than the continuous gene units. Nonetheless previous sequence analysis of a region around the transcription initiation site did not reveal significant differences in rDNA genes with and without insertions. We extend such analysis to cover the last two promoter duplications in the spacer and the entire external transcribed spacer up to the 5' cleavage site of the 18S rRNA. Images
Simeone, A; La Volpe, A; Boncinelli, E
Heat-transfer augmentation by straight grid spacers in rod bundles is studied for single-phase flow and for post-critical heat flux dispersed flow. The heat transfer effect of swirling grid spacers in single-phase flow is also examined. Governing heat-transfer mechanisms are analyzed, and predictive formulations are established. For single-phase flow, the local heat transfer at a straight spacer and at its upstream or downstream locations are treated separately. The effect of local velocity increasing near swirling spacer is considered. For post critical heat flux (CHF) dispersed flow, the heat transfer by thermal radiation, fin cooling, and vapor convection near the spacer are calculated. The predictions are compared with experimental data with satisfactory agreement.
Yao, S.C.; Hochreiter, L.E.; Leech, W.J.
We have studied both the mask CD specification and the mask defect specification for spacer patterning technology (SPT). SPT has the possibility of extending optical lithography to below 40nm half-pitch devices. Since SPT necessitates somewhat more complicated wafer process flow, the CD error and mask defect printability on wafers involve more process factors compared with conventional single-exposure process (SEP). This feature of SPT implies that it is very important to determine mask-related specifications for SPT in order to select high-end mask fabrication strategies; those are for mask writing tools, mask process development, materials, inspection tools, and so on. Our experimental studies reveal that both mask CD specification and mask defect specification are somehow relaxed from those in ITRS2007. This is most likely because SPT reduces mask CD error enhanced factor (MEF) and the reduction of line-width roughness (LWR).
Hashimoto, Kohji; Mukai, Hidefumi; Miyoshi, Seiro; Yamaguchi, Shinji; Mashita, Hiromitsu; Kobayashi, Yuuji; Kawano, Kenji; Hirano, Takashi
Despite the overall success of total hip arthroplasty (THA), there has been an increase in the rate of revision hip surgeries performed each year in the United States. These revision surgeries result in several billion dollars in health care costs. Bearing surface wear can result in the need for revision surgery through a variety of mechanisms. Many implant failures necessitating the need for revision surgeries occur secondary to dislocations, which are often related to prothesis wear and eventual loosening of the components. Wear also can lead to osteolysis and may play a role in aseptic loosening. Specific concerns regarding the wear rates of metal-on-polyethylene (the most common bearing surface) have encouraged the manufacture of newer polyethylene implants with improved wear properties, as well as alternative bearing surfaces. The goal is to improve the durability of revision implants and/or reduce the incidence of revision THAs. Revision arthroplasty involves using alternative surfaces, such as replacing the metal femoral head with a ceramic component or changing the entire prosthesis to a metal-on-metal or ceramic-on-ceramic articulation. It is important to review the characteristics of these alternative bearing surface options and their contributions to improved THA tribology and prolonged prosthesis longevity. The choice of a bearing surface for a revision THA should consider factors such as the patient's age and activity level, the cost of the implant, and both the surgeons' and patients' preferences. Although laboratory studies and small clinical trials have generated optimistic results for these alternative implants in vitro and in vivo, much still needs to be learned about the long-term performance of these materials in patients after total hip revision surgery. PMID:21553778
Patel, Deepan; Parvizi, Javad; Sharkey, Peter F
Context: Snapping hip, or coxa saltans, is a vague term used to describe palpable or auditory snapping with hip movements. As increasing attention is paid to intra-articular hip pathologies such as acetabular labral tears, it is important to be able to identify and understand the extra-articular causes of snapping hip. Evidence Acquisition: The search terms snapping hip and coxa sultans were used in PubMed to locate suitable studies of any publication date (ending date, November 2008). Results: Extra-articular snapping may be caused laterally by the iliotibial band or anteriorly by the iliopsoas tendon. Snapping of the iliopsoas tendon usually requires contraction of the hip flexors and may be difficult to differentiate from intra-articular causes of snapping. Dynamic ultrasound can help detect abrupt tendon translation during movement, noninvasively supporting the diagnosis of extra-articular snapping hip. The majority of cases of snapping hip resolve with conservative treatment, which includes avoidance of aggravating activities, stretching, and anti-inflammatory medication. In recalcitrant cases, surgery to lengthen the iliotibial band or the iliopsoas tendon has produced symptom relief but may result in prolonged weakness. Conclusions: In treating active patients with snapping soft tissues around the hip, clinicians should recognize that the majority of cases resolve without surgical intervention, while being mindful of the potential for concomitant intra-articular and internal snapping hips.
Metal-on-metal hip-bearing components with different percentages of carbon content (low and high carbon) were tested in 6 different configurations using a hip joint simulator. The aim of this study was to characterize metallurgical and tribological events occurring at the articulating surfaces of these articulations. Also, ion release was evaluated and correlated with wear. After the test, for the high-carbon components, carbides were observed below the matrix surface. In the low-carbon content components, most carbides were "carbide-free", while a minority were worn below the matrix surface with increased test cycles. In the cast alloy components, some carbides were pulled out resulting in micropits. Scanning microscope electron characterization of the tested specimens showed scratches and holes. The surface showed a dominant severe wear mechanism due to third-body particles. A greater amount of ions was released in the lubricant used during the wear test for the smaller diameter compared with the bigger one. This study showed that the metallurgical and tribological events taking place at the articulating surfaces of metal-metal hip implants are numerous and complex. The surface morphology after the test showed the effect of more critical working conditions with smaller diameters. PMID:22198601
Affatato, Saverio; Traina, Francesco; Ruggeri, Oddone; Toni, Aldo
Background Femoral offset influences the forces at the hip and the implant stresses after revision THR. For extended bone defects, these forces may cause considerable bending moments within the implant, possibly leading to implant failure. This study investigates the influences of femoral anteversion and offset on stresses in the Wagner SL revision stem implant under varying extents of bone defect conditions. Methods Wagner SL revision stems with standard (34 mm) and increased offset (44 mm) were virtually implanted in a model femur with bone defects of variable extent (Paprosky I to IIIb). Variations in surgical technique were simulated by implanting the stems each at 4° or 14° of anteversion. Muscle and joint contact forces were applied to the reconstruction and implant stresses were determined using finite element analyses. Results Whilst increasing the implant's offset by 10 mm led to increased implant stresses (16.7% in peak tensile stresses), altering anteversion played a lesser role (5%). Generally, larger stresses were observed with reduced bone support: implant stresses increased by as much as 59% for a type IIIb defect. With increased offset, the maximum tensile stress was 225 MPa. Conclusion Although increased stresses were observed within the stem with larger offset and increased anteversion, these findings indicate that restoration of offset, key to restoring joint function, is unlikely to result in excessive implant stresses under routine activities if appropriate fixation can be achieved.
In this paper, new bolaform cholesteryl imide derivatives with different spacers were designed and synthesized. Their gelation behaviors in 23 solvents were investigated, and some of them were found to be low molecular mass organic gelators. The experimental results indicated that these as-formed organogels can be regulated by changing the flexible/rigid segments in spacers and organic solvents. Suitable combination of flexible/rigid segments in molecular spacers in the present cholesteryl gelators is favorable for the gelation of organic solvents. Scanning electron microscopy and atomic force microscopy observations revealed that the gelator molecules self-assemble into different aggregates, from wrinkle and belt to fiber with the change of spacers and solvents. Spectral studies indicated that there existed different H-bond formations between imide groups and assembly modes, depending on the substituent spacers in molecular skeletons. The present work may give some insight into the design and character of new organogelators and soft materials with special molecular structures.
Abnormal or excessive force on the anterior hip joint may cause anterior hip pain, subtle hip instability and a tear of the acetabular labrum. We propose that both the pattern of muscle force and hip joint position can affect the magnitude of anterior joint force and thus possibly lead to excessive force and injury. The purpose of this study was to determine the effect of hip joint position and of weakness of the gluteal and iliopsoas muscles on anterior hip joint force. We used a musculoskeletal model to estimate hip joint forces during simulated prone hip extension and supine hip flexion under 4 different muscle force conditions and across a range of hip extension and flexion positions. Weakness of specified muscles was simulated by decreasing the modeled maximum force value for the gluteal muscles during hip extension and the iliopsoas muscle during hip flexion. We found that decreased force contribution from the gluteal muscles during hip extension and the iliopsoas muscle during hip flexion resulted in an increase in the anterior hip joint force. The anterior hip joint force was greater when the hip was in extension than when the hip was in flexion. Further studies are warranted to determine if increased utilization of the gluteal muscles during hip extension and of the iliopsoas muscle during hip flexion, and avoidance of hip extension beyond neutral would be beneficial for people with anterior hip pain, subtle hip instability, or an anterior acetabular labral tear.
Lewis, Cara L.; Sahrmann, Shirley A.; Moran, Daniel W.
The invention has for its object the provision of an intravascular implant that has mechanical characteristics and physiological characteristics and is very low in cell cytotoxicity and provides an intravascular implant having an implant body made of a metal material that contains gadolinium and magnesium and is free of yttrium.
We report an 85-year-old woman with dementia and dependent for normal life activities who was admitted due to a left periprosthetic tibial fracture. The tibial component was replaced by one with a long stem and she was discharged. Four weeks after the intervention the patient was re-admitted due to an acute prosthetic joint infection. All the components were removed and a bone-cement spacer with a handmade stem with a metal core was implanted. Radiological signs of fracture consolidation were observed after 3 months of follow-up. Due to the previous health status of the patient, it was decided to keep the spacer as a definitive treatment. After 24 months, the patient was able to sit without pain and to stand up with help using a knee brace. There were no radiological or clinical signs of infection.
Font-Vizcarra, LluIs; Izquierdo, Oscar; GarcIa-NuNo, Laura; GonzAlez, Araceli; Diaz-Brito, VicenC; Castellanos, Juan
This report presents the case of a patient in whom hip resurfacing arthroplasty failed because of loosening of the acetabular shell secondary to debonding of the surface coating. During normal function, there will inevitably be cyclic shear stress between the coating and the surrounding bone. This might result in fatigue failure of the bond. In spite of increasing numbers of porous coated acetabular shells being implanted, little is known about the fatigue performance of the interface between coating and implant. PMID:21473459
Delport, Hendrik P; Van Backle, Bart; De Schepper, Jo
We report our results after ten year follow-up of 107 consecutive ABG-I hip prostheses implanted between June 1990 and December 1992: Only 84 prostheses were still in the study after ten years, but only six patients had undergone surgical revision. We can consider our clinical outcomes as excellent, with a whole-implant survival rate greater than 96%, a mean Merle D’Aubigne
V. Canales Cortés; J. J. Panisello Sebastiá; A. Herrera Rodríguez; A. Peguero Bona; A. Martínez Martín; L. Herrero Barcos; L. García-Dihinx
Background: Orthopedic implants and their fixatives contain materials with carcinogenic potential. Whether these implants are linked to subsequent can- cer development remains unknown, mainly because large-scale, long-term follow-up data are scarce. Methods: We conducted a nationwide cohort study in Sweden to examine cancer incidence among 116 727 patients who underwent hip replacement surgery during the pe- riod from 1965 through
Lisa B. Signorello; Jon P. Fryzek; Loren Lipworth; Joseph F. Fraumeni; William J. Blot; Joseph K. McLaughlin; Olof Nyrén
[Purpose] This study aimed to determine the effect of varying hip flexion angle on hip muscle activity during isometric contraction in abduction. [Subjects] Twenty-seven healthy men (mean age=21.5?years, SD=1.2) participated in this study. [Methods] Surface electromyography (EMG) was recorded of the upper portion of the gluteus maximus (UGM), lower portion of the gluteus maximus (LGM), tensor fasciae latae (TFL), and gluteus medius (GMed) during isometric contraction under two measurement conditions: hip flexion angle (0, 20, 40, 60, and 80 degrees) and abduction of the hip joint at 20, 40, 60, and 80% maximum strength. Integrated EMG (IEMG) were calculated and normalized to the value of maximum voluntary contraction (MVC). [Results] Results indicated that the IEMG of both the UGM and LGM increased significantly with increases in hip flexion angle, whereas the IEMG of the TFL decreased significantly. The maximum activities of the UGM and the LGM were 85.7 ± 80.8%MVC and 38.2 ± 32.9%MVC at 80 degrees of hip flexion, respectively, and that of the TFL was 71.0 ± 39.0%MVC at 40 degrees of hip flexion. [Conclusion] The IEMG of the GMed did not change with increases in hip flexion angle. Hip flexion angle affected the activity of the GM and TFL during isometric contraction in abduction.
Fujisawa, Hiroyuki; Suzuki, Hiroto; Yamaguchi, Emi; Yoshiki, Hiromi; Wada, Yui; Watanabe, Aya
Patients with chronic instability or late dislocation following total hip arthroplasty often require operative management. Unfortunately, there is an increased risk of recurrent dislocation following revision in these patients. Over the past decade the use of constrained devices for patients with chronic instability has gained increased interest; however, there is a paucity of studies available in the literature regarding the use of these devices. The purpose of this study was to analyze the available literature over the past 15 years, focusing on larger, long-term studies, to obtain recommendations from the respective articles for indications and contraindications for the use of constrained devices. Our review of eight reports included 1,199 hips in 1,148 patients with a total mean follow-up of 51 months (range, 24 to 124 months). The mean rate of dislocation following revision with a constrained liner was 10% and the mean re-operation rate for reasons other than dislocation was 4%. We concluded that constrained liners are an option for patients who have failed management of instability with other implants, those with instability of unclear etiology, those with cognitive problems who are unable to follow dislocation precautions, those with deficient abductors, and elderly or low-demand individuals with well-positioned implants requiring revision. PMID:16927089
Williams, J T; Ragland, P S; Clarke, S
Patients with chronic instability or late dislocation following total hip arthroplasty often require operative management. Unfortunately, there is an increased risk of recurrent dislocation following revision in these patients. Over the past decade the use of constrained devices for patients with chronic instability has gained increased interest; however, there is a paucity of studies available in the literature regarding the use of these devices. The purpose of this study was to analyze the available literature over the past 15 years, focusing on larger, long-term studies, to obtain recommendations from the respective articles for indications and contraindications for the use of constrained devices. Our review of eight reports included 1,199 hips in 1,148 patients with a total mean follow-up of 51 months (range, 24 to 124 months). The mean rate of dislocation following revision with a constrained liner was 10% and the mean re-operation rate for reasons other than dislocation was 4%. We concluded that constrained liners are an option for patients who have failed management of instability with other implants, those with instability of unclear etiology, those with cognitive problems who are unable to follow dislocation precautions, those with deficient abductors, and elderly or low-demand individuals with well-positioned implants requiring revision.
Ragland, P. S.; Clarke, S.
Hot isostatic pressing (HIP) was used in a new procedure to produce hydroxyapatite (HA) coatings on a commercially pure titanium (cpTi) substrate for osseous implantation. Eighteen HIP-processed HA-coated implants were placed in the inferior border of the mandibles in 2 Labrador retriever dogs and left submerged for 3 months. As control specimens, 12 sandblasted cpTi implants were placed in the same mandibles and, to compare the bone reaction, 2 additional plasma-sprayed HA-coated implants (Integral) were placed. Tissue reactions at the bony interfaces of the implants were studied in ground sections with the implants in situ, using ordinary, fluorescent, and polarized light microscopy and scanning electron microscopy (SEM). The HIP-processed HA coatings displayed an increased density in light microscopy and SEM as compared to plasma-sprayed coatings. Direct bone-implant contact was found in all 3 types of surfaces. However, the production of new bone was far more abundant for the HA-coated implants than for sandblasted cpTi implants. The presence of bone-forming and bone-resorbing cells indicated active bone remodeling in the interface area at 3 months after implant placement. The present results support the view that epitaxial bone growth may occur from the HA-coated implant surface. It was concluded that the increased density of the present HIP-processed HA material does not reduce the bioactive properties of the coatings. PMID:9857595
Wie, H; Herø, H; Solheim, T
During the process of prokaryotic CRISPR adaptation, a copy of a segment of foreign deoxyribonucleic acid referred to as protospacer is added to the CRISPR cassette and becomes a spacer. When a protospacer contains a neighboring target interference motif, the specific small CRISPR ribonucleic acid (crRNA) transcribed from expanded CRISPR cassette can protect a prokaryotic cell from virus infection or plasmid transformation and conjugation. We show that in Escherichia coli, a vast majority of plasmid protospacers generate spacers integrated in CRISPR cassette in two opposing orientations, leading to frequent appearance of complementary spacer pairs in a population of cells that underwent CRISPR adaptation. When a protospacer contains a spacer acquisition motif AAG, spacer orientation that generates functional protective crRNA is strongly preferred. All other protospacers give rise to spacers oriented in both ways at comparable frequencies. This phenomenon increases the repertoire of available spacers and should make it more likely that a protective crRNA is formed as a result of CRISPR adaptation.
Shmakov, Sergey; Savitskaya, Ekaterina; Semenova, Ekaterina; Logacheva, Maria D.; Datsenko, Kirill A.; Severinov, Konstantin
In a nuclear fuel assembly having a parallel array of fuel rods, at least one of the fuel rods which is described, serves as a spacer capture rod. The fuel rods are positioned for longitudinally extending through openings formed from intersecting walls of a grid spacer. Some of the walls are flat and others of the walls have protrusions extending into the openings and coacting springs for holding the fuel rods in laterally fixed positions. The protrusions and springs are horizontally and vertically oriented, relative to the longitudinal axes of the fuel rods. A spacer capture system which secures the grid spacer in fixed position relative to the fuel rods, comprises a cylindrical-like sleeve rigidly fixed to the spacer capture rod. The sleeve includes a longitudinal guide slot; and spaced apart horizontally oriented pairs of vertically opposed bosses extending radially outward from the outer face of an upper portion of the sleeve for engaging at least one of the protrusions from the grid spacer walls; at least one vertically oriented slot located in a lower portion of the sleeve for receiving and locking against one of the springs, the coaction therebetween substantially preventing axial rotation of the capture rod relative to the grid spacer.
\\u000a Pelvic, hip, and thigh injuries are relatively rare in the young athlete (1). The young athlete with pelvic or hip pain may present with an acute injury necessitating immediate treatment. An acute\\u000a injury may cause pain in the pelvic, hip, thigh, or even knee region. More commonly, the young athlete will have a chronic\\u000a injury that will limit activities during
Jason H. Nielson
Particulate wear debris in totally replaced hips causes adverse local host reactions. The extreme form of such a reaction, aggressive granulomatosis, was found to be a distinct condition and different from simple aseptic loosening. Reactive and adaptive tissues around the totally replaced hip were made of proliferation of local fibroblast like cells and activated macrophages. Methylmethacrylate and high-molecular-weight polyethylene were shown to be essentially immunologically inert implant materials, but in small particulate form functioned as cellular irritants initiating local biological reactions leading to loosening of the implants. Chromium-cobalt-molybdenum is the most popular metallic implant material; it is hard and tough, and the bearings of this metal are partially self-polishing. In total hip implants, prerequisites for longevity of the replaced hip are good biocompatibility of the materials and sufficient tribological properties of the bearings. The third key issue is that the bearing must minimize frictional shear at the prosthetic bone-implant interface to be compatible with long-term survival. Some of the approaches to meet these demands are alumina-on-alumina and metal-on-metal designs, as well as the use of highly crosslinked polyethylene for the acetabular component. In order to avoid the wear-based deleterious properties of the conventional total hip prosthesis materials or coatings, the present work included biological and tribological testing of amorphous diamond. Previous experiments had demonstrated that a high adhesion of tetrahedral amorphous carbon coatings to a substrate can be achieved by using mixing layers or interlayers. Amorphous diamond was found to be biologically inert, and simulator testing indicated excellent wear properties for conventional total hip prostheses, in which either the ball or both bearing surfaces were coated with hydrogen-free tetrahedral amorphous diamond films. Simulator testing with such total hip prostheses showed no measurable wear or detectable delamination after 15,000,000 test cycles corresponding to 15 years of clinical use. The present work clearly shows that wear is one of the basic problems with totally replaced hips. Diamond coating of the bearing surfaces appears to be an attractive solution to improve longevity of the totally replaced hip. PMID:14768485
Anterior hip or groin pain is a common complaint for which people are referred for physical therapy. We have observed that people with anterior hip pain often walk in greater hip extension than people without anterior hip pain, and that the pain is reduced when they walk in less hip extension. Therefore, we investigated anterior hip joint forces which may contribute to anterior hip pain and examined the effect of end range hip extension on the anterior hip joint force during gait. To do this, we used a 6 degree of freedom, 3-dimensional musculoskeletal model to estimate hip joint forces during gait. Within subjects, the maximum anterior hip joint force for gait trials with the most hip extension was compared to the anterior hip joint force for gait trials with the least hip extension. The musculoskeletal model indicated that increasing the maximum end range hip extension when walking results in an increase in the anterior hip joint force when compared to walking in less hip extension. Walking in greater hip extension may result in an increase in the anterior hip joint force, and thereby contribute to anterior hip pain. The findings of this study provide some evidence supporting the use of gait modification to reduce anterior hip force when treating people with anterior hip pain.
Lewis, Cara L.; Sahrmann, Shirley A.; Moran, Daniel W.
Complications associated with hip arthroscopy occur between 1.6% and 5%. Fortunately, with the greater understanding of the causes and advancements in techniques and equipment, the incidence is declining. Most of the complications were transient neuropraxias and fluid extravasations resulting in no permanent damage. Severe scuffing of two femoral heads and one case of avascular necrosis were considered serious and permanent, thereby resulting in a 0.5% rate in our series for significant complications. PMID:11675890
Sampson, T G
Arthroscopy of the hip is a relatively new addition to the orthopedic armamentarium. Eriksson, of Sweden, has been a pioneer in studying the force needed to distract the hip joint to allow adequate arthroscopic viewing. Johnson, of Michigan, has provided information on techniques including landmarks, needle positioning and cannula entry. Glick, of California, has described the lateral position for ease of entry of arthroscopic instruments just superior to the greater trochanter. A mini-arthrotomy technique has been used to sublux the femoral head anteriorly from the acetabulum to allow anterior viewing and debridement. An initial series of such procedures in 12 patients resulted in general improvement in symptoms of younger patients with localized articular cartilage defects. Results in older patients with diffuse osteoarthritic changes involving most of the weight-bearing zone of the femoral head were unsatisfactory, however, with most of those patients requiring total hip arthroplasty, within one to two years. Recently, arthroscopy of the hip has been performed in the outpatient surgery department under general endotracheal anesthesia in the lateral decubitus position. Mechanical distraction with 9-18 kg of force has been used routinely, without postoperative neurologic symptoms. Specially adapted long arthroscopes and powered synovial resectors and abraders have been used. In addition, pressurized saline inflow with 100 mmHg of pressure has provided improved joint visualization. Especially helpful has been the availability of angled arthroscopes, including 30 degrees, 60 degrees, and 90 degrees arthroscopes. Potential complications include inadvertent cartilage scuffing, broken instruments, neovascular injury to nearby structures, and local infection. Systemic complications such as pulmonary embolus must always by considered.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2582677
Hawkins, R B
Abstract: Metal on metal hip resurfacing has been used widely over the last ten years but there has been recent concern about destructive soft tissue reactions, which have been called pseudotumours by some authors. This has generated considerable controversy. This review explains why pseudotumours occur after resurfacing and how they can be prevented. It also supports the continued use of resurfacing in appropriate patients by appropriately trained surgeons. PMID:21698574
Murray, David W; Grammatopoulos, George; Gundle, Roger; Gibbons, C L Max H; Whitwell, Duncan; Taylor, Adrian; Glyn-Jones, Sion; Pandit, Hemant G; Ostlere, Simon; Gill, Harinderjit S; Athanasou, Nick; McLardy-Smith, Peter
\\u000a The tribology and wear of different types of bearings for hip prostheses is compared and their ability to meet the clinical\\u000a needs of different types of patients is assessed. Solutions for reducing wear in high-demand patients are described. Wear\\u000a performance is assessed under standard walking conditions and also under adverse conditions, which can result in increased\\u000a wear rates for some
We retrospectively evaluated the postoperative results of total hip arthroplasty (THA) in patients presenting with Crowe group IV dislocated hips. Overall, results were compared with regard to the type of osteotomy performed (Z or oblique) to define the correct indications for surgical technique and choice of prosthetic implant. Thirty-three subtrochanteric shortening and derotational osteotomies in primary THA were performed in 26 patients secondary to congenital hip dislocation. A Z osteotomy was performed in 14 cases and an oblique osteotomy in 19. The surgical approach was direct lateral, and surgery was aimed at restoring the anatomic hip center. Femoral and acetabular fixation was uncemented. The most used stem was the S-ROM (DePuy, Leeds, United Kingdom), and the couplings used were ceramic-ceramic (7 cases), ceramic-polyethylene (3 cases), metal-polyethylene (15 cases), and metal-metal (3 cases). Mean follow-up was 88±45 months. According to the Merle D'Aubigné score, the overall clinical results were good in 23 cases, satisfactory in 6, and fair in 4. Union of the osteotomy occurred in 97% of cases, and the mean time required for osteotomy union was 6±2 months without significant differences between Z and oblique osteotomies. At last follow-up, there was loosening of 1 cup and 1 stem, and revision was necessary. Twelve percent of patients experienced postoperative dislocation and 9% developed neuropraxia of the femoral nerve. The clinical and radiological results were similar in both groups, with a high rate of pain relief, an improvement in limb-length discrepancy, and reduced limping, leading to a smaller or no insole. Currently, the more complex Z osteotomy has been abandoned, because a modular stem prosthesis with metaphyseal sleeve allows the oblique osteotomy to be used with an easier and shorter surgical procedure. PMID:21815571
Dallari, Dante; Pignatti, Giovanni; Stagni, Cesare; Giavaresi, Gianluca; Del Piccolo, Nicolandrea; Rani, Nicola; Veronesi, Francesca; Fini, Milena
Snapping hip, or coxa saltans, presents as an audible or palpable snapping that occurs around the hip during movement and can be associated with or without pain. The prevalence of snapping hip is estimated to occur in up to 10% of the general population, but it is especially seen in athletes such as dancers, soccer players, weight lifters, and runners. Although the snapping sound can be readily heard, the diagnostic cause may be a clinical challenge. The causes of snapping hip have been divided into two distinct categories: extra-articular and intra-articular. Extra-articular snapping hip can be further subdivided into external and internal causes. Advances in imaging techniques have improved the diagnostic accuracy of the various causes of snapping hip, mainly by providing real-time imaging evaluation of moving structures during the snapping phase. Image-guided treatments have also been useful in the diagnostic work-up of snapping hip given the complexity and multitude of causes of hip pain. We discuss the common and uncommon causes of snapping hip, the advanced imaging techniques that now give us a better understanding of the underlying mechanism, and an image-guided diagnostic and therapeutic algorithm that helps to identify surgical candidates. PMID:23787983
Lee, Kenneth S; Rosas, Humberto G; Phancao, Jean-Pierre
Twenty patients underwent operative arthroscopic procedures of the hip joint. All procedures were performed with the patient in the supine position on a standard fracture table using fluoroscopy through three arthroscopic portals (anterolateral, anterior paratrochanteric, and posterior paratrochanteric). The initial indications were therapeutic in 16 patients: loose bodies in four, synovial chondromatosis in three, rheumatoid arthritis in five, ankylosing spondylitis in one, septic arthritis in one, avascular necrosis of femoral head in one, and primary osteoarthritis in one. In four patients who had unexplained hip pain, the initial indications were diagnostic: minimal synovial change was seen in two patients, a synovial chondromatosis was present in another, and a tear of the acetabular labrum and hypertrophy of ligament teres were present in a fourth patient. In one patient who had primary osteoarthritis, the insertion of the arthroscopic instrument into the hip joint failed because of profuse osteophytes along the acetabular rim. Twelve of the 19 patients showed significant improvement of the symptoms after the arthroscopic procedure, but seven patients had no benefit from the procedure. One patient had a postoperative reflex sympathetic dystrophy. PMID:9728170
Kim, S J; Choi, N H; Kim, H J
Drawing on literature searches and professional experience, this article discusses the treatment of asthma with pressurised metered dose inhalers (pMDIs). It demonstrates the need for pMDIs, and presents the health and cost benefits of using a pMDI through a spacer device. Through the review and evaluation of studies, it demonstrates the importance of correct asthma management and the use of spacers. Although there are many types of spacer, and patients often have less than optimal technique, there is evidence to support the overall benefits of use against non-use. PMID:23240220
Controversy exists regarding the possibility of predicting hip reducibility in the congenitally dislocated hip, with arthrography still regarded as the gold standard in this situation. This study aims at assessing the degree of concordance between ultrasonography and arthrography in the detection of anatomic elements obstructing hip reduction. Forty-nine hips were studied both by ultrasonography and arthrography. Three anatomic sources of obstruction to reduction were assessed in each hip: ligamentum teres hypertrophy, inverted labrum, and the presence of soft tissue in the acetabulum. For each variable, congruence between ultrasound and arthrography was measured by kappa analysis. Values > 0.40 expressed sufficient concordance, and they were detected with regard to inverted labrum and the presence of soft tissue in the acetabulum. The results of this study suggest that ultrasonography may be considered a reliable technique for the prediction of the main causes of obstruction in the congenitally dislocated hip, such as inverted labrum and soft tissue in the acetabulum. PMID:10513361
Abril, J C; Berjano, P; Díaz, A
Objective: To compare the use of uncemented implants in total hip arthroplasty in patients with rheumathologic diseases and mechanical osteoarthrosis. Methods: We retrospectively evaluated 196 patients who were operated by the Hip and Arthroplasty Surgery Group of the IOT-HCFMUSP between 2005 and 2009. Patients were divided into two groups: mechanical causes (165 patients) and rheumathologic causes (31 patients). Groups were compared between each other in age, gender and follow-up time. Osseointegration rate and percentage of failure in arthroplasty were evaluated. Results: No statistically significant difference was found in osseointegration rates (in both femoral and acetabular components) in both groups. The rates of revision surgery and implant survival also did not show statistically significant differences. Conclusion: The use of uncemented total hip arthroplasty did not show worse results in rheumathologic patients. Level of Evidence III, Retrospective Case Control Study.
Ejnisman, Leandro; Leonhardt, Nathalia Zalc; Fernandes, Laura Fillipini Lorimier; Leonhardt, Marcos de Camargo; Vicente, Jose Ricardo Negreiros; Croci, Alberto Tesconi
Rehabilitation and patient satisfaction following a modified anterolateral approach for implantation of a total hip replacement (THR) were reviewed following 72 consecutive cases. The Harris Hip and Merle d'Aubigné Scores were recorded at 6 and 12 weeks postoperatively. The patient's satisfaction with regard to the surgical result and the need for analgesia for mobilization were recorded. Rehabilitation was assessed by postoperative crutch use.Significant improvements of the Harris Hip and Merle d'Aubigné scores were demonstrated. All patients thought their surgical outcome was good or better. 2 patients needed pain medicine on an irregular basis and 4 patients used crutches at 12 weeks. This study demonstrates patient satisfaction and satisfactory rehabilitation following a modified antero-lateral approach for minimally-invasive implantation of THR. PMID:20041384
Walde, Tim Alexander; Blattgerste, Dirk; Sehmisch, Stefan; Kuttler, Wolfgang; Walde, Hans-Joachim; Köster, Georg
A 51 year-old man developed an extensive osteolytic response to wear debris in an uncemented porous-coated total hip arthroplasty,\\u000a with metal\\/polyethylene interface, which had been implanted eighteen years previously. This reaction, which involved the upper\\u000a femur and the ilium, produced a mass which compressed the pelvic viscera.
C. Jeanrot; M. Ouaknine; P. Anract; M. Forest; B. Tomeno
We describe 4 patients pooled from our patient populations who presented with groin pain at different periods postoperatively after implantation of a metal-on-metal hip resurfacing. Each patient underwent exploratory surgery after radiographic imaging, hematologic testing, and microbiological assessment of joint aspirations failed to explain their symptoms. Samples of periprosthetic tissues revealed extensive amounts of lymphocytic infiltrates that were suggestive of
Pat Campbell; Andrew Shimmin; Len Walter; Michael Solomon
Metal-on-metal articulations are increasingly used in total hip arthroplasty. Patients can be sensitive to metal ions produced by the articulation and present with pain or early loosening. Infection must be excluded. Correct diagnosis before revision surgery is crucial to implant selection and operation planning. There is no practical guide in the literature on how to differentiate between allergy and infection
Leela C. Biant; Warwick J. M. Bruce; Hans van der Wall; William R. Walsh
Over the last several years, many orthopaedic surgeons have embraced so-called alternative bearing surfaces in total hip arthroplasty, largely on the basis of the hypothesis that a reduction in the volumetric wear rates afforded by these improved articulating couples will reduce the prevalence of osteolysis and aseptic loosening, which in turn will improve implant survivorship. We conducted the study on
P. Botez; C. I. Stoica; P. D. Sirbu; R. Asaftei; C. Grierosu
Production of inflammatory mediators (IM) by cells and specifically macrophages around loosened implants may be responsible for their loosening. Our hypothesis was that different materials give rise to different amounts of these IM. It is thought that alumina\\/alumina for total hip replacement (THR), which has been used for 15 years in our orthopedic department, may produce less IM than other
L. Sedel; J. Simeon; A. Meunier; J. M. Villette; S. M. Launay
Modern hip joint replacements are designed to minimise wear problems. The most popular metal-on-polyethylene components are being updated by harder metal and ceramic combinations. However, this has also been shown to influence the friction moments, which could overload the interface between the implant and the body. In this study custom test apparatus was used to measure the joint moments in
N. E. Bishop; F. Waldow; M. M. Morlock
. The authors evaluated the histological findings from periprosthetic material retrieved around acetabular and femoral components of 24 revision operations from 24 patients who had previously received cementless total hip arthroplasty or hemiarthroplasty. The indication for revision was aseptic loosening in 20 patients, technical error during implantation in two patients, periprosthetic femoral fracture with subsequent loosening in one patient, and
M. Repanti; M. Stamatakis; A. Baikousis; Z. Papazisis; P. Korovessis
Prosthetic joint infection (PJI) due to Brucella spp. is extremely rare. We report the case of a prosthetic hip infection due to Brucella melitensis in a 51-year-old male patient. The initial presentation was a gluteal abscess. There was radiographic evidence of implant loosening. The patient was cured after prolonged treatment with streptomycin, rifampicin, and doxycycline, followed by 2-stage exchange of
Daniel Tena; Oscar Romanillos; Manuel Rodríguez-Zapata; Basilio de la Torre; María Teresa Pérez-Pomata; Ramón Viana; José María Chaves; Julia Bisquert
To evaluate a porous fiber titanium composite as a fixation method, total hip arthroplasty was performed in 13 large male mongrel dogs. In seven both acetabular and femoral composites were fixed with a porous titanium fiber composite, and in the other six the acetabulum was fixed with acrylic cement. The animals were killed one, three, and six months following implantation. At autopsy all components were fixed by bony ingrowth. There was progressive remodeling of the ingrown bone and of the bone trabeculae surrounding the prosthesis in the three- and six-month animals, with gradual thickening and development of haversian structures. Cortical osteoporosis, which did not appear to be progressive, was detected in both the one- and six-month specimens. PMID:6851333
Chen, P Q; Turner, T M; Ronnigen, H; Galante, J; Urban, R; Rostoker, W
This study reports the outcome of total hip arthroplasty with use of an uncemented, tapered stem with a 5- to 9-year follow-up. The first 200 consecutive patients (214 hips) undergoing total hip arthroplasty with the Accolade TMZF stem (Stryker Orthopaedics, Mahwah, NJ) were enrolled prospectively. Follow-up for these patients averaged 7.6 years and encompassed review of clinical records as well as review of serial anteroposterior and lateral radiographs. There were 5 revision surgeries for aseptic loosening, 2 cases of infection, instability, and polyethylene wear. Our failure rate, defined as hips needing revision, was 2.6%, and the failure rate due to aseptic loosening of the femoral component was 0.6%. These results demonstrate the high success rate of this implant providing support for its continued use. PMID:21466945
Casper, David S; Kim, Gregory K; Restrepo, Camilo; Parvizi, Javad; Rothman, Richard H
Due to the well-documented problems surrounding metal-on-metal bearings, the use of hip resurfacing has declined. Since the potential benefits of hip resurfacing remain desirable, it may be beneficial to investigate the long-term outcome of hip resurfacings using metal-on-polyethylene in the 1980's. We report the long-term survivorship and modes of failure of a cementless metal-on-polyethylene resurfacing (n = 178) with different porous ingrowth surfaces. While acetabular loosening was absent, a high incidence of femoral failures (femoral loosening = 18.1%, osteolytic neck fracture = 21%) occurred despite using the same ingrowth surface for both components. Ongoing developments using the lessons learned from these previous generation components and utilizing modern low wear materials, e.g., cross-linked polyethylene, may lead to improved implants for future hip resurfacings. PMID:24090660
Tan, Timothy L; Ebramzadeh, Edward; Campbell, Patricia A; Al-Hamad, Mariam; Amstutz, Harlan C
Objective To assess the risk of cancer associated with modern primary metal-on-metal hip replacements. Design Population based study. Setting Nationwide retrospective comparative register. Participants 10?728 patients who underwent metal-on-metal total hip arthroplasty and 18?235 patients who underwent conventional metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic total hip arthroplasty (the non-metal-on-metal cohort) in the Finnish Arthroplasty Register 2001-10. Data on cancer cases up to 2010 for these cohorts were extracted from the Finnish Cancer Registry. Main outcome measures The relative risk of cancer was expressed as the ratio of observed to expected number of cases from the Finnish population—that is, the standardised incidence ratio. The relative risk of cancer in the metal-on-metal cohort compared with the non-metal-on-metal cohort was estimated with analyses of these ratios and Poisson regression. Results The overall risk of cancer in patients with metal-on-metal hip implants was similar to that in the Finnish population (378 observed v 400 expected, standardised incidence ratio 0.95, 95% confidence interval 0.85 to 1.04). The overall risk of cancer in patients with metal-on-metal hip implants was also no higher than in patients who had received non-metal-on-metal hip implants (relative risk 0.92, 0.81 to 1.05). Conclusions Metal-on-metal hip replacements are not associated with an increased overall risk of cancer during a mean follow-up of four years.
Recent reports in the literature strongly support the idea that cement is the optimum form of fixation of the femoral component in total hip replacement. For hybrid total hip arthroplasty, we used a cemented cup instead of an uncemented cup since this was inevitable in cases of poorly developed acetabulum. The uncemented cone femoral component is also beneficial in cases
Y. Y. Kim; B. J. Kim; H. S. Ko; Y. B. Sung; S. K. Kim; J. C. Shim
The main reason for the revision of total hip replacements is aseptic loosening, caused by stress shielding and wear particle induced osteolysis. In order to detect an implant loosening early, the osseointegration of endoprosthetic implants must be measured exactly. Currently applied diagnostic methods, such as standard radiographs and clinical symptomatology, often result in an imprecise diagnosis. A novel radiation-free method to improve the diagnostic investigation of implant loosening is presented. The osseointegration of an implant can be identified using mechanical magnetic sensors (oscillators), which impinge on small membranes inside an implant component, e.g., the femoral hip stem. The maximum velocity after impingement of the oscillator depends on the osseointegration of the implant. Excitation of the oscillator is realized by a coil outside the human body. Another external coil is used to detect the velocity of the oscillator. To demonstrate the principle of the novel loosening sensor, an overdimensioned test device was designed to measure simulated loosening phases in the first experimental tests with different material layers. The overdimensioned test device of the loosening sensor showed significant differences in the various phases of fixation. Analysis of the membrane without any material layer in the case of advanced loosening resulted in a 23% higher maximum velocity compared to an attached artificial bone layer. Based on these preliminary results, the sensor system shows potential for the detection of implant loosening. Moreover, the proposed system could be used in experimental applications to determine the quality of bioactive coatings and new implant materials. PMID:22070337
Ruther, Cathérine; Ewald, Hartmut; Mittelmeier, Wolfram; Fritsche, Andreas; Bader, Rainer; Kluess, Daniel
Pseudotumours are a rare complication of hip resurfacing. They are thought to be a response to metal debris which may be caused by edge loading due to poor orientation of the acetabular component. Our aim was to determine the optimal acetabular orientation to minimise the risk of pseudotumour formation. We matched 31 hip resurfacings revised for pseudotumour formation with 58 controls who had a satisfactory outcome from this procedure. The radiographic inclination and anteversion angles of the acetabular component were measured on anteroposterior radiographs of the pelvis using Einzel-Bild-Roentgen-Analyse software. The mean inclination angle (47 degrees, 10 degrees to 81 degrees) and anteversion angle (14 degrees, 4 degrees to 34 degrees) of the pseudotumour cases were the same (p = 0.8, p = 0.2) as the controls, 46 degrees (29 degrees to 60 degrees) and 16 degrees (4 degrees to 30 degrees) respectively, but the variation was greater. Assuming an accuracy of implantation of +/- 10 degrees about a target position, the optimal radiographic position was found to be approximately 45 degrees of inclination and 20 degrees of anteversion. The incidence of pseudotumours inside the zone was four times lower (p = 0.007) than outside the zone. In order to minimise the risk of pseudotumour formation we recommend that surgeons implant the acetabular component at an inclination of 45 degrees (+/- 10) and anteversion of 20 degrees (+/- 10) on post-operative radiographs. Because of differences between the radiographic and the operative angles, this may be best achieved by aiming for an inclination of 40 degrees and an anteversion of 25 degrees. PMID:20675749
Grammatopoulos, G; Pandit, H; Glyn-Jones, S; McLardy-Smith, P; Gundle, R; Whitwell, D; Gill, H S; Murray, D W
Purpose To assess the safety and effectiveness of a novel, minimally invasive interspinous spacer in patients with moderate lumbar spinal stenosis (LSS). Methods A total of 53 patients (mean age, 70 ± 11 years; 45% female) with intermittent neurogenic claudication secondary to moderate LSS, confirmed on imaging studies, were treated with the Superion® Interspinous Spacer (VertiFlex, Inc, San Clemente, CA) and returned for follow-up visits at 6 weeks, 1 year, and 2 years. Study endpoints included axial and extremity pain severity with an 11-point numeric scale, Zurich Claudication Questionnaire (ZCQ), back function with the Oswestry Disability Index (ODI), health-related quality of life with the Physical Component Summary (PCS) and Mental Component Summary (MCS) scores from the SF-12, and adverse events. Results Axial and extremity pain each decreased 54% (both P < 0.001) over the 2-year follow-up period. ZCQ symptom severity scores improved 43% (P < 0.001) and ZCQ physical function improved 44% (P < 0.001) from pre-treatment to 2 years post-treatment. A statistically significant 50% improvement (P < 0.001) also was noted in back function. PCS and MCS each improved 40% (both P < 0.001) from pre-treatment to 2 years. Clinical success rates at 2 years were 83%–89% for ZCQ subscores, 75% for ODI, 78% for PCS, and 80% for MCS. No device infection, implant breakage, migration, or pull-out was observed, although two (3.8%) patients underwent explant with subsequent laminectomy. Conclusion Moderate LSS can be effectively treated with a minimally invasive interspinous spacer. This device is appropriate for select patients who have failed nonoperative treatment measures for LSS and meet strict anatomical criteria.
Shabat, Shay; Miller, Larry E; Block, Jon E; Gepstein, Reuven
Purpose To evaluate clinical results of two-stage revision using a modified articulating spacer for treatment of infected total knee arthroplasty (TKA). Materials and Methods We retrospectively reviewed 20 cases treated by two-stage revision arthroplasty using a modified articulating spacer under the diagnosis of infected TKA from January 2006 to December 2011. The mean follow-up period was 22.3 months. The first operation consisted of debridement after removal of the prosthesis, reinsertion of the femoral component after autoclaving, and implantation of antibiotic-loaded cement with a new polyethylene in the proximal tibia. Results The mean period between the primary TKA and the first stage operation was 39 months and between the first stage operation and the revision arthroplasty was 3.3 months. The average range of motion (ROM) increased from 69.8° preoperatively to 102.8° postoperatively (p<0.001). The mean Knee Society knee score increased from 33.8 points to 85.3 points (p<0.001). The mean Knee Society function score increased from 35 points to 87.5 points (p<0.001). The mean Hospital for Special Surgery score increased from 57.6 points preoperatively to 82.6 points postoperatively (p<0.001). Two cases (10%) were re-infected after the revision arthroplasty. Conclusions Two-stage revision arthroplasty using an articulating cement spacer can be an effective therapy not only for the treatment of an infected TKA but also for recovery of knee ROM and function.
Kim, Young Soo; Cho, Chul Hyun; Lee, Kyung Jae; Sohn, Eun Seok; Kim, Beom Soo
Objective To determine the extent to which prostheses with no readily available evidence to support their use are being implanted in primary total hip arthroplasty. Design Systematic review of the literature. Data sources The 9th annual report of the National Joint Registry of England and Wales (NJR) was analysed to identify prostheses with an Orthopaedic Data Evaluation Panel rating of “unclassified” or “pre-entry” used in primary total hip arthroplasty in 2011. A systematic review of those prostheses was carried out using PubMed, Cochrane, Embase, OVID, and Google databases. Study selection Prostheses used in primary total hip arthroplasty as published in the NJR’s 9th annual report were analysed. Only literature that included the name of the prosthesis was included. Literature yielded in the search results was excluded if it reported animal, non-orthopaedic, non-total hip arthroplasty, or non-device related studies. Results The systematic review found that 24% (57/235) of all hip replacement implants available to surgeons in the UK have no evidence for their clinical effectiveness. It also shows that 10?617 (7.8%) of the 136?593 components used in primary hip replacements in 2011 were implanted without readily identifiable evidence of clinical effectiveness. These comprised 157 cemented stems (0.5% of 34?655 implanted), 936 (2.8% of 33?367) uncemented stems, 1732 (7.1% of 24?349) cemented cups, and 7577 (17.1% of 44?222) uncemented cups. Conclusions This study shows that a considerable proportion of prostheses available to orthopaedic surgeons have no readily available evidence of clinical effectiveness to support their use. Concern exists about the current system of device regulation, and the need for a revised process for introducing new orthopaedic devices is highlighted.
New material combinations and designs of artificial hip implants are being introduced in an effort to improve proprioception and functional longevity. Larger joints in particular are being developed to improve joint stability, and it is thought that these larger implants will be more satisfactory for younger and more physically active patients. The study detailed here used a hip friction simulator to assess the friction and lubrication properties of large-diameter hip bearings of metal-on-metal and ceramic-on-reinforced-polymer couplings. Joints of different diameters were evaluated to determine what effect, if any, bearing diameter had on lubrication. In addition, the effects of lubricant type are considered, using carboxymethyl cellulose and bovine calf serum, and the physiological lubricant is shown to be considerably more effective at reducing friction. The frictional studies showed that the metal-on-metal joints worked under a mixed lubrication regime, producing similar friction factor values to each other. The addition of bovine calf serum (BCS) reduced the friction. The ceramic-on-reinforced-polymer samples were shown to operate with high friction factors and mixed lubrication. When tested with BCS, the larger-diameter bearings showed a decrease in friction compared with the smaller-size bearings, and the addition of BCS resulted in an increase in friction, unlike the metal-on-metal system. The study demonstrated that the component's diameter had little or no influence on the lubrication and friction of the large bearing combinations tested. PMID:20839653
Flanagan, S; Jones, E; Birkinshaw, C
Resurfacing hip arthroplasty is an alternative to conventional arthroplasty and it is indicated in young and active patients. Good results and the prevention of complications stem from a meticulous surgical technique and proper patient selection. We present herein the case of a 43 year-old patient who, after undergoing bilateral hip replacement with resurfacing prostheses, sustained a non-simultaneous fracture of both femoral necks due to avascular necrosis. He was treated by placing a metaphyseal anchoring stem. Postoperative X-rays showed proper implant placement without femoral notching, with a discrete 7 degrees valgus alignment of the femoral component. Both passive and active mobility was painful. X-rays showed cervical fracture of the right femur. The femoral head was attached to the implant, with no metallosis nor loosening of the femoral or acetabular components, but the bone had a fragmented and friable appearance that histopathologically was defined as avascular necrosis. Femoral neck fracture is the main complication after resurfacing hip arthroplasty. The effect of other factors like bone necrosis due to cement is unknown. PMID:22512114
Sanz-Ruiz, P; Chana-Rodríguez, F; Villanueva-Martínez, M; Vaquero-Martín, J
The majority of cemented femoral hip replacements fail as a consequence of loosening. One design feature that may affect loosening rates is implant surface finish. To determine whether or not surface finish effects fatigue damage accumulation in a bone cement mantle, we developed an experimental model of the implanted proximal femur that allows visualisation of damage growth in the cement
A. B. Lennon; B. A. O. McCormack; P. J. Prendergast
The success of radioactive implant therapy for head and neck carcinomas depends critically on careful planning and execution of the implant procedure. In this paper we discuss our experience with oral tongue and floor of mouth implants, and some innovations introduced to facilitate these procedures. Implants were carried out using standard angiocatheters modified with magnetic caps at the open end and terminated with Teflon spacers and lead shot at the closed end. The importance of accurate source placement and careful determination of the target dose rate is discussed with numerical examples. Differential hot-loading of sources is clearly indicated in cases of extension of the lesion to the dorsal or lateral tongue surface. For dorsal surface extension the use of Teflon spacers at the closed ends of the catheters helps to ensure adequate coverage of the target volume with the higher dose region enclosing the demonstrable tumor. All 10 patients implanted with this technique are controlled without recurrence at a median follow-up of 38 months. The two complications observed appeared to be associated with excessive hot-loading of edge plane sources.
Schmidt-Ullrich, R.; Zwicker, R.D.; Wu, A.; Kelly, K. (Medical College of Virginia, Richmond (USA))
Chronic inflammation and infection of the nasal sinuses, also referred to as Chronic Rhinosinusitis (CRS), severely affects patients’ quality of life. Adhesions, ostial stenosis, infection and inflammation relapses complicate chronic sinusitis treatment strategies. Drug-eluting stents, packings or implants have been suggested as reasonable alternatives for addressing these concerns. This article reviewed potential drug candidates for nasal implants, formulation methods/optimization and characterization methods. Clinical applications and important considerations were also addressed. Clinically-approved implants (Propel™ implant, the Relieva stratus™ MicroFlow spacer, and the Sinu-Foam™ spacer) for CRS treatment was an important focus. The advantages and limitations, as well as future considerations, challenges and the need for additional research in the field of nasal drug implant development, were discussed.
Parikh, Ankit; Anand, Utkarshini; Ugwu, Malachy C.; Feridooni, Tiam; Massoud, Emad; Agu, Remigius U.
Chronic inflammation and infection of the nasal sinuses, also referred to as Chronic Rhinosinusitis (CRS), severely affects patients' quality of life. Adhesions, ostial stenosis, infection and inflammation relapses complicate chronic sinusitis treatment strategies. Drug-eluting stents, packings or implants have been suggested as reasonable alternatives for addressing these concerns. This article reviewed potential drug candidates for nasal implants, formulation methods/optimization and characterization methods. Clinical applications and important considerations were also addressed. Clinically-approved implants (Propel™ implant, the Relieva stratus™ MicroFlow spacer, and the Sinu-Foam™ spacer) for CRS treatment was an important focus. The advantages and limitations, as well as future considerations, challenges and the need for additional research in the field of nasal drug implant development, were discussed. PMID:24871904
Parikh, Ankit; Anand, Utkarshini; Ugwu, Malachy C; Feridooni, Tiam; Massoud, Emad; Agu, Remigius U
After the rapid growth in the use of CoCrMo metal-on-metal hip replacements since the second generation was introduced circa 1990, metal-on-metal hip replacements have experienced a sharp decline in the last two years due to biocompatibility issues related to wear and corrosion products. Despite some excellent clinical results, the release of wear and corrosion debris and the adverse response of local tissues have been of great concern. There are many unknowns regarding how CoCrMo metal bearings interact with the human body. This perspective article is intended to outline some recent progresses in understanding wear and corrosion of metal-on-metal hip replacement both in-vivo and in-vitro. The materials, mechanical deformation, corrosion, wear-assisted corrosion, and wear products will be discussed. Possible adverse health effects caused by wear products will be briefly addressed, as well as some of the many open questions such as the detailed chemistry of corrosion, tribochemical reactions and the formation of graphitic layers. Nowadays we design almost routinely for high performance materials and lubricants for automobiles; humans are at least as important. It is worth remembering that a hip implant is often the difference between walking and leading a relatively normal life, and a wheelchair.
Liao, Yifeng; Hoffman, Emily; Wimmer, Markus; Fischer, Alfons; Jacobs, Joshua; Marks, Laurence
The nuclear ribosomal locus coding for the large subunit is represented in tandem arrays in the plant genome. These consecutive\\u000a gene blocks, consisting of several regions, are widely applied in plant phylogenetics. The regions coding for the subunits\\u000a of the rRNA have the lowest rate of evolution. Also the spacer regions like the internal transcribed spacers (ITS) and external\\u000a transcribed
Péter Poczai; Jaakko Hyvönen
A low pressure drop spacer is disclosed for positioning and retaining the fuel rods of a nuclear fuel assembly in which a plurality of upper and lower spring forks which extend through apertures in the side wall of the spacer into the assembly and through apertures in grid members which divide the assembly. The intersection and superposition of the spring forks, side wall and grid members form fuel rod passageways through which the fuel rods extend. 10 figs.
Patterson, J.F.; Bjornard, T.A.
Self Aligned Double Patterning (SADP) is now widely accepted as a viable technology for the further extension of 193nm immersion lithography towards the 22nm /18nm technology nodes. SADP was primary introduced for the manufacturing of flash memory due to its 1D design geometry. However, SADP is now becoming a main stream technology for advanced technology nodes for logic product. SADP results in alignment marks with reduced image contrast after completion of spacer patterning. Consequently there is an elevated risk that the alignment performance of the cut lithography layer on the spacer  may be negatively impacted. Initial studies indicate that it may be necessary to consider new mark designs. In this paper, we will evaluate different types of SADP processes with the alignment system of the Nikon S620D and S621D immersion scanner. We will discuss the performances and the differences observed due to the SADP materials. Included in this study is an intensive characterization of the morphology of the spacer after SADP process. We will use for this a 3D-AFM from Insight, and characterize the spacer profile of the spacer. Using a standard AFM microscope, we can characterize the surface roughness in the inner and the outer part of the wafer. The self aligned spacer process results in asymmetric spacers. Two types of surface (inside and outside) of the spacer are formed. The impact of this asymmetry is also assessed. The roughness difference, between the two parts, will play an important roll in the alignment contrast.
Lattard, L.; McCallum, M.; Morton, R.; Fujiwara, T.; Makino, K.; Tokui, A.; Takahashi, N.; Sasamoto, S.
Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.
Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun
Hip dysplasia is considered to be one of the most serious problems in dog breeding. In the past 20 years the studies of, and the attempts to control, this condition have been directed mainly to the overall picture of the abnormality of the hips. The various efforts have resulted in a decrease in the incidence of HD in several breeds
We report the case of a girl, aged 2 years, who was able to dislocate her right hip voluntarily and in whom there was no other abnormality. She was given psychological treatment and the condition resolved after 2 years. Eight similar cases of habitual dislocation of the hip are reported in the world literature.
J. Heras; A. Hidalgo; S. Garcia Mata; M. Martinez Grande
This study was conducted to determine the effect of waiting times for total hip arthroplasty in terms of loss in quality-adjusted life years and additional burden perceived. A second goal was to study the effect of waiting times and preoperative function scores on postoperative outcome scores. Data were collected prospectively from a cohort of 161 patients waiting for total hip
Marieke Ostendorf; Erik Buskens; Henk van Stel; Augustus Schrijvers; Louis Marting; Wouter Dhert; Abraham Verbout
Prevalence of malnutrition, particularly undernutrition, increases with advancing age, and patients with hip fracture are often particularly malnourished and\\/or undernourished. Deficiency in both micronutrients and macronutrients appears to be strongly implicated in the pathogenesis and the consequences of hip fracture in osteoporotic elderly. Such deficiencies can accelerate age-dependent bone loss, increase the propensity to fall by impairing movement coordination, and
J.-P. Bonjour; M.-A. Schurch; R. Rizzoli
The relationship between parity, lactation and the occurrence of hip fracture was investigated in a case-control study of white women. The cases were patients (n=174) aged 45 years and over with a radiologically confirmed first hip fracture sampled from among admissions to 30 hospitals in New York and Philadelphia between September 1987 and July 1989. Controls (n=174) were selected from
S. Hoffman; J. A. Grisso; J. L. Kelsey; M. D. Gammon; L. A. O'Brien
Hip-hop music and culture are often cited as being public pedagogy, meaning the music itself has intrinsic educational value. Non-profit organizations and individual educators have graciously taken the lead in utilizing hip-hop to educate. As the academy continues to debate its effectiveness, teachers and community organizers are moving forward.…
Hall, Marcella Runell
Bone loss around the femoral stems during the insertion of a standard prosthesis is a major problem in hip arthroplasty. Moreover, long periods of use of the standard metallic prosthesis often lead to revision surgery because of disuse osteoporosis (stress shielding). The main factor behind this problem is the material-stiffness mismatch of the bone and implant, with the latter consisting of metals such as stainless steel, Co-Cr-Mo alloy, or Ti6Al4V alloy. Our study aimed to decrease the factor of geometric mismatch by designing and making customized hip prostheses from computed tomography scan data and finite element analysis. Therefore, the inner medullar cavity of the femur would match exactly with the prosthesis. Our results showed that the desired stress-strain values were close to the physiological level. We observed that the maximum Von Mises stresses for the bone and implant were 41.8 MPa and 197 MPa, respectively. An optimization analysis of the taper angle of the prosthesis hip ball for fixation with the stem has also been performed, in which the angle was found to be approximately 2 deg. The taper angle plays an important role in load transfer and safe levels of stress-strain using various ball materials. PMID:20402628
Ghosh, U B; Sengupta, D; Roychowdhury, Amit; Pal, S
This invention relates to a nuclear reactor spacer grid member for use in a liquid cooled nuclear reactor and to a ductless core component employing a plurality of these spacer grid members. The spacer grid member is of the egg-shell type and is constructed so that the walls of the cell members of the grid member are formed of a single thickness of metal to avoid tolerance problems. Within each cell member is a hydraulic spring which laterally constrains the nuclear material bearing rod which passes through each cell member against a hardstop in response to coolant flow through the cell member. This hydraulic spring is also suitable for use in a water cooled nuclear reactor. A core component constructed of, among other components, a plurality of these spacer grid members, avoids the use of a full length duct by providing spacer sleeves about the sodium tubes passing through the spacer grid members at locations between the grid members, thereby maintaining a predetermined space between adjacent grid members.
Christiansen, D.W.; Karnesky, R.A.
Abstract Spacers and valved holding chambers (VHCs) are pressurized metered dose inhaler (pMDI) accessory devices, designed to overcome problems that patients commonly experience when administering aerosol via a pMDI. Spacers were developed in direct response to patient-related issues with pMDI technique, particularly, poor coordination between actuation and inhalation, and local side-effects arising from oropharyngeal deposition. Current clinical guidelines indicate the need for widespread prescription and use of spacers, but, despite their apparent ubiquity, the devices themselves are, unfortunately, all too commonly "disused" by patients. An understanding of the background from which spacers developed, and the key factors influencing the optimization of the spacer and the later VHC, is crucial to developing an appreciation of the potential of these devices, both contemporary and future, for improving the delivery of pressurized aerosols to patients. This review, informed by a full patent search and an extensive scientific literature review, takes into account the clinical and laboratory evidence, commercial developments, and the sometimes serendipitous details of scientific anecdotes to form a comprehensive perspective on the evolution of spacers, from their origins, in the early days of the pMDI, up to the present day. PMID:25054481
Nikander, Kurt; Nicholls, Clare; Denyer, John; Pritchard, John
The patterned ion implantation ``PARTIAL IMPLANT'' has been developed as a productivity improvement tool. The Partial Implant can form several different ion dose areas on the wafer surface by controlling the speed of wafer moving and the stepwise rotation of twist axis. The Partial Implant system contains two implant methods. One method is ``DIVIDE PARTIAL IMPLANT,'' that is aimed at reducing the consumption of the wafer. The Divide Partial Implant evenly divides dose area on one wafer surface into two or three different dose part. Any dose can be selected in each area. So the consumption of the wafer for experimental implantation can be reduced. The second method is ``RING PARTIAL IMPLANT'' that is aimed at improving yield by correcting electrical characteristic of devices. The Ring Partial Implant can form concentric ion dose areas. The dose of wafer external area can be selected to be within plus or minus 30% of dose of wafer central area. So the electrical characteristic of devices can be corrected by controlling dose at edge side on the wafer.
Hino, Masayoshi; Miyamoto, Naoki; Sakai, Shigeki; Matsumoto, Takao
Massive, irreparable rotator cuff tears are a source of pain and disability. Although most rotator cuff tears can be completely repaired, a significant number are considered massive and irreparable. Numerous operative techniques have been described for the treatment of these kinds of tears including arthroscopic debridement, biceps tenotomy, tendon transfer, grafting, and reverse arthroplasty. We describe a surgical technique using a biodegradable subacromial balloon spacer (InSpace; OrthoSpace, Kfar Saba, Israel) implanted between the humeral head and acromion that permits smooth, frictionless gliding, restoring the shoulder biomechanics. The technique is easy to perform and is less invasive than the conventional surgical techniques available, and it may potentially serve as a bridging option in patients with massive, irreparable tears who are normally candidates for reverse arthroplasty.
Savarese, Eugenio; Romeo, Rocco
The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1? is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1?, VEGF and TNF-?) to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages) and in vivo. HIF-1? in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1? with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell) induced significantly elevated HIF-1?, VEGF, TNF-? and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1? was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n?=?5) compared to failed Metal-on-Polymer articulating hip arthroplasties (n?=?10). This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy), can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths. PMID:23840602
Samelko, Lauryn; Caicedo, Marco S; Lim, Seung-Jae; Della-Valle, Craig; Jacobs, Joshua; Hallab, Nadim J
The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1? is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1?, VEGF and TNF-?) to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages) and in vivo. HIF-1? in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1? with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell) induced significantly elevated HIF-1?, VEGF, TNF-? and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1? was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n?=?5) compared to failed Metal-on-Polymer articulating hip arthroplasties (n?=?10). This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy), can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths.
Samelko, Lauryn; Caicedo, Marco S.; Lim, Seung-Jae; Della-Valle, Craig; Jacobs, Joshua; Hallab, Nadim J.
Polyethylene wear debris induced osteolysis has triggered investigations to find alternative material combinations to the well-established metal-on-polyethylene hip implants. Owing to some early successful clinical cases, metal-on-metal (MoM) hip replacements have been attracting more and more interest. There is, however, considerable concern about the propensity of MoM hip replacements to release metal ions and fine, nanometre-scale metallic wear debris. The long-term effect from released metal ions and wear particles is still not clear. To date, all the work on hip simulators focused on assessing mass losses damage has been referred to as 'wear'. However, it is known in the field of tribocorrosion that mechanical removal of the passive layer on Co-Cr alloys can significantly enhance corrosion activity. In total joint replacements, it is possible that corrosion plays a significant role. However, no one has ever tried to extract, on a hip simulator, what proportion of the damage is due to mechanical processes and the corrosion processes. This paper describes the first instrumentation of an integrated hip joint simulator to provide in-situ electrochemical measurements in real time. The open circuit potential results are reported to assess the corrosion regime in the absence and presence of movement at the bearing surfaces. The importance of these measurements is that the real damage mechanisms can be assessed as a function of the operating cycle. PMID:21218689
Yan, Y; Neville, A; Dowson, D; Williams, S; Fisher, J
Introduction Intervertebral spacers are made of different materials, which can affect the postfusion magnetic imaging (MRI) scans. Susceptibility\\u000a artifacts especially for metallic implants can decrease the image quality. This study aimed to determine whether magnesium\\u000a as a lightweight and biocompatible metal is suitable as a biomaterial for spinal implants based on its MRI artifacting behavior.\\u000a \\u000a \\u000a \\u000a Materials and methods To compare artifacting behaviors,
Thorsten Ernstberger; Gottfried Buchhorn; Gabert Heidrich
In this tutorial we describe the basic principles of the ion implantation technique and we demonstrate that emission Mössbauer spectroscopy is an extremely powerful technique to investigate the atomic and electronic configuration around implanted atoms. The physics of dilute atoms in materials, the final lattice sites and their chemical state as well as diffusion phenomena can be studied. We focus on the latest developments of implantation Mössbauer spectroscopy, where three accelerator facilities, i.e., Hahn-Meitner Institute Berlin, ISOLDE-CERN and RIKEN, have intensively been used for materials research in in-beam and on-line Mössbauer experiments immediately after implantation of the nuclear probes.
Langouche, G.; Yoshida, Y.
After reviewing recent literature on the treatment of displaced intracapsular fractures of the femoral neck (Garden types III and IV) and from personal experience, a number of conclusions can be made. Orthopedic surgeons and hospitals face the challenge of providing the treatment most beneficial to patients with intracapsular, subcapital hip fractures in the most cost-effective way. The numbers of patients will increase annually and exceed the 125,000 per year at present in the United States. Most authors agree that fractures with the least displacement and younger, more demanding patients will do well with a precise fracture reduction without delay and an accurately placed internal fixation system. However, an overall median risk for reoperation 2 years after internal fixation is 35%. A patient with a displaced intracapsular fracture will need to consider monopolar, bipolar, or THA as the treatment of choice. Monopolar and bipolar arthroplasty have a reduced survivorship compared to THA and are not as suitable for the younger, more active patient. A large femoral head implant leads to decreased motion from increased friction and an undersized head implant leads to reduced contact area with increased erosion and pain. Bipolar arthroplasties, while allowing early mobilization, may develop some of the characteristics of monopolar implants if motion is not mainly at the internal joint. The increased cost may not justify their use over monopolar arthroplasty. Should dislocation occur, monopolar implants are easier to reduce (closed) than bipolar. Ceramic heads on monopolar or bipolar arthroplasties offer reduced wear and less erosion of the acetabulum. Total hip arthroplasty provides early mobilization, long-term pain relief, and little additional morbidity at surgery. The increased rate of early dislocation may be related to surgeon skill rather than an inherent failure of the system. If the early dislocators are removed from consideration, the complication rate drops to equal that of monopolar and bipolar implants. Total hip arthroplasty also is cost effective. Total hip arthroplasty may be the only option if pre-existing arthritis, significant osteoporosis, or Paget's disease of the pelvis is present. PMID:12650332
The indications for hip arthroscopy are expanding as the understanding of hip disease increases. Improved instrumentation and technical skills also have facilitated the ability to treat some hip disorders arthroscopically. Femoroacetabular impingement (FAI) is increasingly recognized as a disorder that can lead to progressive intra-articular chondral and labral injury. Although FAI is usually treated through an open approach, limited-open and all-arthroscopic approaches have been described. Various arthroscopic techniques allow treatment of labral and acetabular rim pathology as well as peripheral compartment femoral head-neck abnormalities. Early outcomes of limited-open and all-arthroscopic treatment of FAI are only beginning to be reported but appear to compare favorably with those of open dislocation procedures. Although labral tears traditionally have been treated with simple débridement, concerns have been raised about the consequences of removing the labrum. Modified portal placement and hip-specific suture anchors are now being used in an effort to repair some labral tears. Snapping hip disorders typically are treated nonsurgically. For persistent symptoms, arthroscopic release is successful, compared with open release, and allows additional evaluation of the hip joint during surgery. Diagnosis and management of traumatic and atraumatic hip instability continue to be challenging. Hip arthroscopy has been shown to be effective in the treatment of hip instability in some patients. The extra-articular peritrochanteric space is receiving increased attention. The arthroscopic anatomy has been well defined, but the treatment of greater trochanteric pain syndrome and arthroscopic repair of abductor tendon tears are only beginning to be reported. Improved techniques and longer-term outcomes studies will further define the optimal role of hip arthroscopy. PMID:19385552
Larson, Christopher M; Guanche, Carlos A; Kelly, Bryan T; Clohisy, John C; Ranawat, Anil S
Modular neck implants are an attractive treatment tool in total hip replacement. Concerns remain about the mechanical stability and metal ion release caused by the modular connection. Five different implant designs were investigated in an experimental set-up. In vivo conditions were simulated and the long-term titanium release was measured. Finally, the modular connections were inspected for corrosion processes and signs of fretting. No mechanical failure or excessive corrosion could be identified for the implants tested. The titanium releases measured were extremely low compared to in vivo and in vitro studies and were not in a critical range.
Jakubowitz, Eike; Krachler, Michael; Thomsen, Marc; Heisel, Christian
Modular neck implants are an attractive treatment tool in total hip replacement. Concerns remain about the mechanical stability and metal ion release caused by the modular connection. Five different implant designs were investigated in an experimental set-up. In vivo conditions were simulated and the long-term titanium release was measured. Finally, the modular connections were inspected for corrosion processes and signs of fretting. No mechanical failure or excessive corrosion could be identified for the implants tested. The titanium releases measured were extremely low compared to in vivo and in vitro studies and were not in a critical range. PMID:19219434
Kretzer, J Philippe; Jakubowitz, Eike; Krachler, Michael; Thomsen, Marc; Heisel, Christian
Modern total hip arthroplasty delivers excellent and reproducible results. New implant developments include a wide range of implants with a bone and tissue sparing design, including short femoral stems. This review was performed to provide an overview on the currently published survival results of short stems to allow comparison with the results of traditional hip stems. A literature search was performed to identify publications on short stems with a "modern" trochanter sparing design including implant survival information. Information was collected on the study population, follow-up time, implants used, implant survival and functional scores. The revision rate per 100 observed component years was calculated and compared to data presented in national arthroplasty registries. The methodological quality was assessed by employing a score specific to survival assessment of hip stems. In the course of 16 individual searches in EMBASE and Medline, 460 potentially eligible articles were identified. After thorough screening, 14 articles were deemed applicable. The variability in quality of the publications was high. No association between survival outcome and publication quality was apparent. The total revision rate over all studies was found to be 0.38 per 100 component years with endpoint "stem revision for any reason". The survival rate of these stems is encouraging and appears to be comparable with that of more traditional uncemented stems. However, only few mid-term and long-term studies are available. Reports with longer follow-up are needed to draw further conclusions. PMID:22878970
Rometsch, Elke; Bos, Pieter K; Koes, Bart W
Edge loading causes clinical problems for hard-on-hard hip replacements, and edge loading wear scars are present on the majority of retrieved components. We asked the question: are the lines of action of hip joint muscles such that edge loading can occur in a well-designed, well-positioned acetabular cup? A musculoskeletal model, based on cadaveric lower limb geometry, was used to calculate for each muscle, in every position within the complete range of motion, whether its contraction would safely pull the femoral head into the cup or contribute to edge loading. The results show that all the muscles that insert into the distal femur, patella, or tibia could cause edge loading of a well-positioned cup when the hip is in deep flexion. Patients frequently use distally inserting muscles for movements requiring deep hip flexion, such as sit-to-stand. Importantly, the results, which are supported by in vivo data and clinical findings, also show that risk of edge loading is dramatically reduced by combining deep hip flexion with hip abduction. Patients, including those with sub-optimally positioned cups, may be able to reduce the prevalence of edge loading by rising from chairs or stooping with the hip abducted. PMID:23575923
van Arkel, Richard J; Modenese, Luca; Phillips, Andrew T M; Jeffers, Jonathan R T
Edge loading causes clinical problems for hard-on-hard hip replacements, and edge loading wear scars are present on the majority of retrieved components. We asked the question: are the lines of action of hip joint muscles such that edge loading can occur in a well-designed, well-positioned acetabular cup? A musculoskeletal model, based on cadaveric lower limb geometry, was used to calculate for each muscle, in every position within the complete range of motion, whether its contraction would safely pull the femoral head into the cup or contribute to edge loading. The results show that all the muscles that insert into the distal femur, patella, or tibia could cause edge loading of a well-positioned cup when the hip is in deep flexion. Patients frequently use distally inserting muscles for movements requiring deep hip flexion, such as sit-to-stand. Importantly, the results, which are supported by in vivo data and clinical findings, also show that risk of edge loading is dramatically reduced by combining deep hip flexion with hip abduction. Patients, including those with sub-optimally positioned cups, may be able to reduce the prevalence of edge loading by rising from chairs or stooping with the hip abducted. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1172–1179, 2013.
van Arkel, Richard J; Modenese, Luca; Phillips, Andrew TM; Jeffers, Jonathan RT
Psoas impingement is a rare cause of persisting pain after hip arthroplasty. Diagnosis is based on clinical examination and exclusion of other complications after arthroplasty by radiographs, ultrasound, CT and blood analysis. The diagnosis is strongly supported by temporary pain relief after infiltration. When conservative measures fail, treatment can consist of a psoas tenotomy or a revision arthroplasty. When there is no obvious cause such as malpositioning for component impingement, psoas release reliably improves pain and function. This procedure is mostly performed through an open approach, which can give significant complications. An arthroscopic technique for psoas tenotomy after hip arthroplasty is described. This report shows that this minimal invasive technique is safe and effective and allows for inspection of the implant in the same session. However, the score used did not improve in a significant way. PMID:21473444
Van Riet, Anne; De Schepper, Jo; Delport, Hendrik Pieter
Due to the increasing number of total hip arthroplasties performed during the last three decades and the limited long-term survival, mainly because of wear, the number of revisions has increased during the last two years. If the implant itself is still considered to be stable, only head and inlay exchange is necessary. This requires comprehensive knowledge of the characteristics of the articulating materials by the surgeon as the wrong choice of wear couple can lead to early failure for a second time. The aim of this paper is to present considerations and strategies for head and inlay exchange in case of failure, either due to wear of the articulation material or of other indications for revision hip arthroplasty.
We reviewed 46 patients who underwent salvage hip arthroplasty (SHA) for revision of failed cannulated screws (CS), sliding hip screws (SHS), or intramedullary nails (IMN). The primary objective was to determine differences in operative difficulty. SHA after failed femoral neck fixation was associated with lower intra-operative demands than after failed peri-trochanteric fractures. Similarly, analysis by the index implant found that conversion arthroplasty after failed CSs was associated with lower intra-operative morbidity than failed SHSs or IMNs; differences between SHS and IMN were not as clear. Importantly, intra-operative data in cases of failed SHSs were similar regardless of the original fracture type, showing the device played a larger role than the fracture pattern. Complications and revision surgery rates were similar regardless of fracture type or fixation device. Our results suggest that operative demands and subsequent patient morbidity are more dependent on the index device than the fracture pattern during SHA. PMID:23489728
DeHaan, Alexander M; Groat, Tahnee; Priddy, Michael; Ellis, Thomas J; Duwelius, Paul J; Friess, Darin M; Mirza, Amer J
Dislocation is a major complication of total hip arthroplasty (THA), whose frequency has been unaffected by improvements in surgical techniques and implants. The dislocation rate depends on multiple factors related to the patient, hip disease, and surgical procedure and is therefore also dependent on the surgeon. The many published studies on THA dislocation, its causes, and its treatment have produced conflicting results. The objective of this work is to review the management of THA dislocation, which is a severe event for both the patient and the surgeon. This lecture starts with a brief review of data on THA dislocation rates and the many factors that influence them. Emphasis is then put on the evaluation for a cause and, more specifically, on the challenges raised by detecting suboptimal cup position. Next, reported techniques for treating THA dislocation and the outcomes of each are discussed. Finally, a management strategy for patients selected for revision surgery is suggested. PMID:24434366
Charissoux, J-L; Asloum, Y; Marcheix, P-S
Total hip and knee arthroplasty are surgical procedures usually performed in older adults aged 65-70 years and more, who suffer from arthritic joint degeneration, in order to relieve pain and improve functioning. In the past decade there have been more and more documentations of younger people, 50-60 years old and even less, who expect to participate in physical activity following these procedures. The trend today is to recommend activities which exert mild pressure on the implants such as swimming, cycling, golf, bowling, walking and cycling. It is not recommended to participate in sports activities that place greater pressure on the implants such as soccer, football, volleyball, handball, basketball, hockey and jogging. Such high-stress activities may cause early loosening of implants, as described in the article by Keren et al. in this issue: "Sport activity after hip and knee arthroplasty". PMID:24416821
Tsur, Azmon; Volpin, Gershon
The aim is to perform the assessment of a modular cementless acetabular cup with a tapered internal design for all bearing couplings. In 190 unselected consecutive patients, 207 total hip arthroplasties were implanted. The implants were clinically and radiographically evaluated. Follow-up was 49.7 ± 8.1 months. The average Harris hip score improved from 55.5 ± 5.7 to 94.7 ± 3.4 (P < 0.05). All cups were well-positioned and stable. The Kaplan-Maier cumulative survivorship was 98.5 ± 0.8%. No significant differences have been noted in dividing patients according to the different liner materials (P < 0.005). The study, whose rationale is the novelty of this kind of implant, suggests the efficacy of the Delta-PF acetabular cup. PMID:22223107
Bistolfi, Alessandro; Massazza, Giuseppe; Rosso, Federica; Ventura, Stefano; Lagalla, Francesco; Crova, Maurizio
An increasing number of patients receive and benefit from osteosynthesis materials or artificial joint replacement. The most common complications are mechanical problems or infection. Metals like nickel, chromium and cobalt as well as bone cement components like acrylates and gentamicin are potential contact allergens which can cause intolerance reactions to implants. Eczema, delayed wound/bone healing, recurrent effusions, pain and implant loosening all have been described as manifestation of implant allergy. In contrast to the high incidence of cutaneous metal allergy, allergies associated with implants are rare. Diagnosis of metal implant allergy is still difficult. Thus differential diagnoses--in particular infection--have to be excluded and a combined approach of allergologic diagnostics by patch test and histopathology of peri-implant tissue is recommended. It is still unknown which conditions induce allergic sensitization to implants or trigger peri-implant allergic reactions in the case of preexisting cutaneous metal allergy. Despite the risk of developing complications being unclear, titanium based osteosynthesis materials are recommended for metal allergic patients and the use of metal-metal couplings in arthroplasty is not recommended for such patients. If the regular CoCr-polyethylene articulation is employed, the patient should give informed written consent. PMID:20204719
Thomas, P; Thomsen, M
... result of an original surgery. There are two types of breast implants approved for sale in the United States: saline- ... Encourage reporting of adverse events associated with breast implants through our Medwatch Reporting System. Related Links Medscape Interview with FDA staff on ...
Background: Little is known about sports activity after total hip resurfacing.Hypothesis: Patients undergoing total hip resurfacing can have a high level of sports activity.Study Design: Case series; Level of evidence, 4.Methods: The authors evaluated the level of sports activities with a standardized questionnaire in 138 consecutive patients (152 hips) 2 years after total hip resurfacing. Range of motion, Harris hip
Marc Banerjee; Bertil Bouillon; Carolin Banerjee; Holger Bäthis; Rolf Lefering; Miriam Nardini; Joachim Schmidt
Total hip prostheses are implanted to younger and more active patients, so the open problem is to create implants which will enhance the implant survivorship and will offer greater longevity. From this point of view, metal-on-metal arthroprostheses are well performing. The volume of periprosthetic inflammatory tissues appears to be less than with metal-on-UHMPWE, however osteolysis often occurs and it is
S. Spriano; E. Vernè; M. G. Faga; S. Bugliosi; G. Maina
It has been hypothesised that AM is ideal for patient specific orthopaedic implants such as those used in bone cancer treatment, that can rapidly build structures such as lattices for bone and tissues to in-grow, that would be impossible using current conventional subtractive manufacturing techniques. The aim of this study was to describe the adoption of AM (direct metal laser sintering and electron beam melting) into the design manufacturing and post-manufacturing processes and the early clinical use. Prior to the clinical use of AM implants, extensive metallurgical and mechanical testing of both laser and electron beam fabrications were undertaken. Concurrently, post-manufacturing processes evaluated included hipping, cleaning and coating treatments. The first clinical application of a titanium alloy mega-implant was undertaken in November 2010. A 3D model of the pelvic wing implant was designed from CT scans. Novel key features included extensive lattice structures at the bone interfaces and integral flanges to fix the implant to the bone. The pelvic device was implanted with the aid of navigation and to date the patient remains active. A further 18 patient specific mega-implants have now been implanted. The early use of this advanced manufacturing route for patient specific implants has been very encouraging enabling the engineer to produce more advanced and anatomical conforming implants. However, there are a new set of design, manufacturing and regulatory challenges that require addressing to permit this technique to be used more widely. This technology is changing the design and manufacturing paradigm for the fabrication of specialised orthopaedic implants.
We describe the use of intraoperative ultrasound for the safe development of arthroscopic portals during hip arthroscopy without the requirement for fluoroscopy. We find this technique consistently accurate, allowing the safe introduction of arthroscopic instruments into the hip with a very low rate of iatrogenic injury. We have further developed the technique for application to both central- and peripheral-compartment procedures. We now have a total experience of more than 700 procedures to date. With the described technique of ultrasound guidance for portal placement, fluoroscopy is required in fewer than 2% of hip arthroscopy procedures at our institution.
Weinrauch, Patrick; Kermeci, Sharon
Background and purpose The aim of short-stem total hip arthroplasty is to preserve proximal bone stock for future revisions, to improve biomechanical reconstruction, and to make minimally invasive approaches easier. It is therefore being increasingly considered to be a sound alternative to conventional total hip arthroplasty, especially for young and active patients. However, it is still unknown whether survival rates of short-stem hips match current standards. We made a systematic summary of reported overall survival after short-stem total hip arthroplasty. Materials and methods We conducted a systematic review of English, French, German, and Dutch literature. 2 assessors independently identified clinical studies on short-stem hip arthroplasty. After recalculating reported revision rates, we determined whether each implant had a projected revision rate of 10% or less at 10 years of follow-up or a revision rate per 100 observed component years of 1 or less. Stems were classified as “collum”, “partial collum”, or “trochanter-sparing”. Results and Interpretation We found 49 studies, or 51 cohorts, involving 19 different stems. There was a large increase in recent publications. The majority of studies included had a follow-up of less than 5 years. We found a large number of observational studies on “partial collum” and “trochanter-sparing” stems, demonstrating adequate survival rates at medium-term follow-up. Clinical evidence from “collum stem” studies was limited to a small number of studies with a medium-term follow-up period. These studies did not show a satisfactory overall survival rate.
van Oldenrijk, Jakob; Molleman, Jeroen; Klaver, Michel; Poolman, Rudolf W; Haverkamp, Daniel
Because of the ageing of the population, an increasing number of patients with hip prostheses are undergoing pelvic irradiation. Treatment planning systems (TPS) currently available are not always able to accurately predict the dose distribution around such implants. In fact, only Monte Carlo simulation has the ability to precisely calculate the impact of a hip prosthesis during radiotherapeutic treatment. Monte Carlo phantoms were developed to evaluate the dose perturbations during pelvic irradiation. A first model, constructed with the DOSXYZnrc usercode, was elaborated to determine the dose increase at the tissue-metal interface as well as the impact of the material coating the prosthesis. Next, CT-based phantoms were prepared, using the usercode CTCreate, to estimate the influence of the geometry and the composition of such implants on the beam attenuation. Thanks to a program that we developed, the study was carried out with CT-based phantoms containing a hip prosthesis without metal artefacts. Therefore, anthropomorphic phantoms allowed better definition of both patient anatomy and the hip prosthesis in order to better reproduce the clinical conditions of pelvic irradiation. The Monte Carlo results revealed the impact of certain coatings such as PMMA on dose enhancement at the tissue-metal interface. Monte Carlo calculations in CT-based phantoms highlighted the marked influence of the implant's composition, its geometry as well as its position within the beam on dose distribution.
Buffard, Edwige; Gschwind, Régine; Makovicka, Libor; David, Céline
Background Dynamic interspinous spacers, such as X-stop, Coflex, DIAM, and Aperius, are widely used for the treatment of lumbar spinal stenosis. However, controversy remains as to whether dynamic interspinous spacer use is superior to traditional decompressive surgery. Methods Medline, Embase, Cochrane Library, and the Cochrane Controlled Trials Register were searched during August 2013. A track search was performed on February 27, 2014. Study was included in this review if it was: (1) a randomized controlled trial (RCT) or non-randomized prospective comparison study, (2) comparing the clinical outcomes for interspinous spacer use versus traditional decompressive surgery, (3) in a minimum of 30 patients, (4) with a follow-up duration of at least 12 months. Results Two RCTs and three non-randomized prospective studies were included, with 204 patients in the interspinous spacer (IS) group and 217 patients in the traditional decompressive surgery (TDS) group. Pooled analysis showed no significant difference between the IS and TDS groups for low back pain (WMD: 1.2; 95% CI: ?10.12, 12.53; P?=?0.03; I2?=?66%), leg pain (WMD: 7.12; 95% CI: ?3.88, 18.12; P?=?0.02; I2?=?70%), ODI (WMD: 6.88; 95% CI: ?14.92, 28.68; P?=?0.03; I2?=?79%), RDQ (WMD: ?1.30, 95% CI: ?3.07, 0.47; P?=?0.00; I2?=?0%), or complications (RR: 1.39; 95% CI: 0.61, 3.14; P?=?0.23; I2?=?28%). The TDS group had a significantly lower incidence of reoperation (RR: 3.34; 95% CI: 1.77, 6.31; P?=?0.60; I2?=?0%). Conclusion Although patients may obtain some benefits from interspinous spacers implanted through a minimally invasive technique, interspinous spacer use is associated with a higher incidence of reoperation and higher cost. The indications, risks, and benefits of using an interspinous process device should be carefully considered before surgery.
Wu, Ai-Min; Zhou, Yong; Li, Qing-Long; Wu, Xin-Lei; Jin, Yong-Long; Luo, Peng; Chi, Yong-Long; Wang, Xiang-Yang
The current study measured ion release among large-head metal-on-metal hip bearings. Twenty-six patients with a modular, Profemur® TL with A-Class® big femoral head total hip replacement were matched (gender, femoral size, BMI) with a group of 26 patients with the Conserve® Plus implant hip resurfacing. Compared with HR patients, THR patients had higher median serum cobalt ion levels at 6 months (3.26 vs 1.12 ?g/L, P = .002) 1 year (4.51 vs 1.02, P = .002), and 2 years (3.77 vs 1.22, P<.001) following surgery. No differences in chromium ions were observed. Further research is required to determine the clinical significance of elevated serum cobalt ions. PMID:21435499
Beaulé, Paul E; Kim, Paul R; Hamdi, Amre; Fazekas, Anna
Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46 mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux. PMID:24726992
Valladares Linares, R; Bucs, Sz S; Li, Z; AbuGhdeeb, M; Amy, G; Vrouwenvelder, J S
In the curative radiotherapy of localized prostate cancer, improvements in biochemical control observed with dose escalation have been counterbalanced by an increase in radiation-induced toxicity. The injection of biodegradable spacers between prostate and rectum represents a new frontier in the optimization of radiotherapy treatments for patients with localized disease. Transperineal injection of different types of spacers under transrectal ultrasound guidance allows creating a 7-to-20mm additional space between the prostate and the anterior rectal wall lasting 3 to 12 months. Dosimetrically, a relative reduction in the rectal volume receiving at least 70Gy (V70) in the order of 43% to 84% is observed with all types of spacers, regardless of the radiotherapy technique used. Preliminary clinical results show for all spacers a good tolerance and a possible reduction in the acute side effects rate. The aim of the present systematic review of the literature is to report on indications as well as dosimetric and clinical advantages of the different types of prostate-rectum spacers commercially available (hydrogel, hyaluronic acid, collagen, biodegradable balloon). PMID:24746454
Zilli, T; Benz, E; Miralbell, R
Self-aligned triple patterning (SATP) technique offers both improved resolution and quasi-2D design flexibility for scaling integrated circuits down to sub-15nm half pitch. By implementation of active layout decomposition/synthesis using mandrel and spacer engineering, SATP process represents a prospective trend that not only drives up the feature density, but also breaks the 1-D gridded limitations posed to future device design. In this paper, we shall present the research progress made in optimizing SATP process to improve its lithographic performance. To solve the previously reported difficulties in etching small mandrels and removing sacrificial spacers, new materials are tested and a promising scheme (using oxide as the mandrel and poly/amorphous Si as the sacrificial spacer) is identified. In the new process, a diluted HF process is applied to shrink the mandrel (oxide) line CD and a highly selective dry etch (which does not attack the mandrel and structural spacer) is developed to strip the sacrificial Si spacers, resulting in significantly improved process performance. We also address the issue of reducing SATP process complexity by exploring the feasibility of a 2-mask concept for specific types of layout.
Chen, Yijian; Cheng, Qi; Kang, Weiling
The paper is devoted to the optimization of the placement of spacer-dampers in bundled conductors of overhead transmission lines. The main purpose of the spacers' use is to align individual conductors in a bundle and to assure the adequate spacing between them. At the same time, however, the spacers may provide damping which is desirable for minimizing the wind-induced vibrations. Such vibrations, via fatigue of conductors, lead to major damage and maintenance costs. Fatigue occurs mainly at the tension and suspension clamps, and also at the spacer clamps. At these points the forces applied to the conductor can, in a first approximation, be assumed as concentrated forces. In the present paper aeolian excitation due to the wind is modelled as a stationary time-and-space-dependent random field, whose spatial and temporal spectra account for yearly distributions of wind speed and turbulence. This assumption allows calculation of the mean square (MSQ) values of bending stresses at the above mentioned critical points. Fatigue accumulation theories for stationary processes provide a direct injective relation between the lifetime of a specimen and the MSQ value of loading; thus, to maximize the conductor's lifetime one should optimize the spacer-dampers as well as their placement, with regard to the maximum of the MSQ bending stresses along the span. We only deal with the optimization of the placement. The maximum of the MSQ of the bending stresses is the cost function. The vibration of conductors is modeled by the wave equation.
Kazimierczyk, P.; Hagedorn, P.
van Diemen, Marcus P J; Colen, Sascha; Dalemans, Alain A R; Stuyck, Jose; Mulier, Michiel
One of the most important issues in the modern total hip arthroplasty (THA) is the bearing surface. Extensive research on bearing surfaces is being conducted to seek an ideal bearing surface for THA. The ideal bearing surface for THA should have superior wear characteristics and should be durable, bio-inert, cost-effective, and easy to implant. However, bearing surfaces that are currently being implemented do not completely fulfill these requirements, especially for young individuals for whom implant longevity is paramount. Even though various new bearing surfaces have been investigated, research is still ongoing, and only short-term results have been reported from clinical trials. Future bearing surfaces can be developed in the following ways: (1) change in design, (2) further improvement of polyethylene, (3) surface modification of the metal, (4) improvement in the ceramic, and (5) use of alternative, new materials. One way to reduce wear and impingement in THA is to make changes in its design by using a large femoral head, a monobloc metal shell with preassembled ceramic liner, dual mobility cups, a combination of different bearing surfaces, etc. Polyethylene has improved over time with the development of highly crosslinked polyethylene. Further improvements can be made by reinforcing it with vitamin E or multiwalled carbon nanotubes and by performing a surface modification with a biomembrane. Surface modifications with titanium nitride or titanium niobium nitride are implemented to try to improve the metal bearings. The advance to the fourth generation ceramics has shown relatively promising results, even in young patients. Nevertheless, further improvement is required to reduce fragility and squeaking. Alternative materials like diamond coatings on surfaces, carbon based composite materials, oxidized zirconium, silicon nitride, and sapphire are being sought. However, long-term studies are necessary to confirm the efficacy of these surfaces after enhancements have been made with regard to fixation technique and implant quality. PMID:24605198
Infections occur in 0.5-5% of cases after implantation of an endoprosthesis and represent one of the most severe complications of artificial joint replacements. Approximately 300,000 primary implantations for hip and knee prostheses are carried out in Germany annually with a corresponding number of early and late infections. This means that approximately 4,000-6,000 cases are to be expected annually. Periprosthetic infections normally lead to a significant loss of function and quality of life for patients and the complex remediation is costly. Therefore, preventive measures, such as perioperative prophylaxis with antibiotics, maintaining highly sterile conditions during operations and an expedient selection of patients are of substantial importance. The basic principles of an adequate restoration include identification of the pathogen, local eradication of the infection mostly after removal of the prosthesis, pathogen-oriented systemic and local antibiotic therapy and finally re-implantation of the revision prosthesis under infection-free conditions. The standard procedure for revision surgery is a two-phase replacement with maintenance of an infection-free interval before renewal of the prosthesis. The use of single-phase or multi-phase strategies, as well as the selection of cemented or cement-free revision, varies between centers as a definitive evaluation is not yet available.The most important parameters for successful treatment of periprosthetic infections have been identified as the earliest possible diagnosis, radical surgical cleansing with an adequate antibiotic therapy and successful restoration has been reported in approximately 80% of cases. Because of the complex therapy regime, treatment in specialized centers is generally recommended especially under the aspect of a demanding patient monitoring. PMID:20361365
Militz, M; Bühren, V
As the population become aged, many patients with hip prosthesis are treated for a pelvic cancer. The recommended ballistic must avoid to pass in the prosthesis, but sometimes it is inevitable. So it is essential to quantify with accuracy the dose modifications linked to the presence of metallic implant. The aim of this study is to analyze by Monte Carlo method these modifications in simple and complex models (anthropomorphic phantom) which take into account the geometry and the composition of the prosthesis and its coatings. Then, this methodology was used to study the behaviour of a treatment planning system in theses extreme conditions. PMID:18248832
Gschwind, R; Buffard, E; Masset, H; David, C; Makovicka, L