Modes of failure of a threaded acetabular cup : a radiographic study with EBRA of 42 revised cups.
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ABSTRACT:
SUBMITTER: Ilchmann T
PROVIDER: S-EPMC2267560 | biostudies-other | 2007 Apr
REPOSITORIES: biostudies-other
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Project description:UNLABELLED: In vitro studies demonstrating excessive wear in polyethylene cups sterilized using gamma irradiation and stored in air led to the abandonment of this sterilization technique. We evaluated the clinical wear performance of a metal femoral component on a polyethylene cup in a hip prosthesis from a selected subset of implants in a group of patients followed for at least 20 years and assessed the time dependency of variation in penetration rates. We measured penetration in 33 polyethylene cups in 25 patients who had a Charnley low-friction arthroplasty between 1982 and 1984. All patients had Charnley Ogee cups implanted for more than 20 years and sterilized using the gamma irradiation in air technique. If degradation occurred over time in vivo, it was not reflected by an increased penetration rate with increasing time in vivo; even after 20 years of implantation, the degree of wear remained low. This suggests gamma irradiation affects wear on ultra-high-molecular-weight polyethylene by reducing wear secondary to the crosslinking, by increasing wear as shown through in vitro studies of heavily oxidized samples, or by oxidation resulting from prolonged shelf life. The effect of progressive oxidation in vivo does not appear to affect wear in vivo. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
| S-EPMC2505130 | biostudies-other
Project description:Background and purposeHydroxyapatite (HA) coating is believed to improve bone-implant ingrowth and long-term survival of prostheses. Recent studies, however, have challenged this view. Furthermore, HA particles may produce third-body wear and initiate aseptic loosening of implants. We report the performance of HA- and porous-coated acetabular cups in a prospective randomized trial.MethodsThis was an 8-year follow-up study of our previously published prospective randomized study to compare clinical outcomes, survival, periprosthetic bone mineral density, migration, and wear rates of HA- and porous-coated acetabular cups. Dual X-ray absorptiometry (DXA) and Ein Bild Roentgen Analyse (EBRA) measurements were used. 100 patients who underwent unilateral cementless total hip arthroplasty were randomized to either porous-coated cups or HA-coated cups. Patients were examined preoperatively and at 3, 6, and 9 months, and also 1, 3, and 8 years after surgery. 81 patients were available for 8-year follow-up, 40 with porous-coated cups and 41 with HA-coated cups.ResultsAge, sex, bone mineral density, and clinical results (Harris hip score) were similar in the 2 groups. The survival, wear, and migration patterns of the cups were also similar in both groups. The results of periprosthetic bone mineral density scans in region of interest 2 was in favor of the porous-coated cups, but there were no differences between the 2 groups in all the remaining regions of interest.InterpretationHA coating had no statistically significant effect on clinical results, survival, wear, or migration at the 8-year follow-up.
| S-EPMC3851667 | biostudies-literature
Project description:We compared clinical results and wear performance in two different generations of a cementless porous-coated cup, analysing the long-term results of 83 uncemented Harris-Galante I cups (32-mm femoral head) and 93 uncemented Harris-Galante II cups (28-mm femoral head). All polyethylene liners were gamma irradiated in air. Polyethylene linear wear was estimated using a software package. The minimum follow-up was 10 years. Nine Harris-Galante I cups and two Harris-Galante II cups were revised due to aseptic loosening or polyethylene problems. The mean femoral head penetration at 6 weeks after surgery was 0.15 +/- 0.05 mm for the Harris-Galante I cups and 0.12 +/- 0.03 for the Harris-Galante II cups (p < 0.001);but mean wear was 0.13 +/- 0.23 mm per year for the Harris-Galante I cups and 0.11 +/- 0.10 for the Harris-Galante II cups (p = 0.740). Most of the metallic shells in both groups showed stable fixation. The so-called second-generation cups had lower initial polyethylene wear that resulted in less polyethylene wear at the latest the follow-up, but the overall wear rate was similar in both groups despite the different femoral head sizes and the improved locking mechanism.
| S-EPMC2269018 | biostudies-other
Project description:BackgroundUncemented press-fit acetabular cups without screws rely on the elastic recoil of the bone for its primary stability and tend to leave polar gaps with its use. The clinical significance of these gaps and the functional outcome of the patients with polar gaps is evaluated in this study.MethodsThis comparative analysis was done on 224 cementless primary THA using Deltamotion® Hip System from January 2010 to December 2017. Patients were divided into two groups based on the presence or absence of polar gaps on immediate post-operative radiographs. Patients were observed for their clinical, radiological and functional outcomes with regular follow ups. At each follow-up, patients' clinical outcome was evaluated using the Harris Hip Score (HHS) and Patient Reported Outcome Measures (PROMs).Results14 of 224 patients(6.25%) demonstrated polar gaps in their immediate post-operative radiographs. No statistically significant difference was noted in the final mean HHS between the two groups. The polar gaps ranged from 0.5 to 1.8?mm (mean-1.09?mm). None of the patients showed progression of the polar gaps. All patients showed bony ingrowth into the gaps at a mean of 8.57 months.ConclusionThe presence of polar gaps in the immediate post-operative radiographs are not of a major clinical significance provided a secure peripheral fit is achieved intra-operatively. The functional outcome and rehabilitation in such patients is at par with that seen in the patients without polar gaps. Disappearance of these polar gaps is a rule rather than an exception.
| S-EPMC6985010 | biostudies-literature
Project description:Background: Acetabular cage reconstruction with bone allografts is among the successful strategies to deal with massive acetabular bone loss. However, the nonbiological fixation nature of cages can compromise long-term success. Tantalum trabecular metal acetabular cups (TM cups) have been used in acetabular revision surgery because of their increased initial stability and good bone ingrowth features. This study was performed to determine whether the bone stock of the acetabulum is enough to support a hemispheric TM cup after failed cage reconstruction with bone allografts. Methods: We retrospectively reviewed patients who received acetabular revision surgery with TM cups after failed cage reconstruction with bone allografts from 2006 to 2017. There were 12 patients (5 males and 7 females) included in this study, with a mean age of 61.5 years (38 to 81) at the time of re-revision surgery. The mean follow-up after re-revision surgery was 8.6 years (2.6 to 13.3). The endpoint was defined as the aseptic loosening of the TM cup and reoperation for any causes. The change in bone stock of the acetabulum between index revision and re-revision was assessed according to the Gross classification for acetabular bone loss. Results: One patient died after eight years of follow-up of a cause not related to hip surgery. Two patients received two-stage revision arthroplasty due to PJI after 3.2 and 9.4 years of follow-up, respectively. The bone stock of the acetabulum was significantly improved between index revision and re-revision surgery (p < 0.0001). The Kaplan-Meier survivorship was 100% with aseptic loosening as the endpoint and 90% and 75% at five- and ten-year follow-up, respectively, with reoperation for any reason as the endpoint. Even cage reconstruction with bone allografts will fail eventually, and the bone stock of the acetabulum will improve after union and incorporation between host bone and allografts. The restored bone stocks will facilitate further revision surgery with hemispheric TM cups. The biological fixation between host bone and tantalum trabecular metal can provide longstanding stability of the TM cup. Conclusions: The results of our study offer a viable option for patients with failed cage reconstruction with bone allografts.
| S-EPMC9224788 | biostudies-literature
Project description:BackgroundTo create a safe zone, an understanding of the combined femoral and acetabular mating during hip motion is required. We investigated the position of the femoral head inside the acetabular liner during simulated hip motion. We hypothesized that cup and stem anteversions do not equally affect hip motion and combined hip anteversion.MethodsHip implant motion was simulated in standing, sitting, sit-to-stand, bending forward, squatting, and pivoting positions using the MATLAB software. A line passing through the center of the stem neck and the center of the prosthetic head exits at the polar axis (PA) of the prosthetic head. When the prosthetic head and liner are parallel, the PA faces the center of the liner (PA position = 0, 0). By simulating hip motion in 1-degree increments, the maximum distance of the PA from the liner center and the direction of its movement were measured (polar coordination system).ResultsThe effect of modifying cup and stem anteversion on the direction and distance of the PA's change inside the acetabular liner was different. Stem anteversion influenced the PA position inside the liner more than cup anteversion during sitting, sit-to-stand, squatting, and bending forward (P = .0001). This effect was evident even when comparing stems with different neck angles (P = .0001).ConclusionCup anteversion, stem anteversion, and stem neck-shaft angle affected the PA position inside the liner and combined anteversion in different ways. Thus, focusing on cup orientation alone when assessing hip motion during different daily activities is inadequate.
| S-EPMC8197737 | biostudies-literature
Project description:Background and purpose - Hip dislocation is one of the most common complications following total hip arthroplasty (THA). Several factors that affect dislocation have been identified, including acetabular cup positioning. Optimal values for cup inclination and anteversion are debatable. We performed a systematic review to describe the different methods for measuring cup placement, target zones for cup positioning, and the association between cup positioning and dislocation following primary THA. Methods - A systematic search of literature in the PubMed database was performed (January and February 2016) to identify articles that compared acetabular cup positioning and the risk of dislocation. Surgical approach and methods for measurement of cup angles were also considered. Results - 28 articles were determined to be relevant to our research question. Some articles demonstrated that cup positioning influenced postoperative dislocation whereas others did not. The majority of articles could not identify a statistically significant difference between dislocating and non-dislocating THA with regard to mean angles of cup anteversion and inclination. Most of the articles that assessed cup placement within the Lewinnek safe zone did not show a statistically significant reduction in dislocation rate. Alternative target ranges have been proposed by several authors. Interpretation - The Lewinnek safe zone could not be justified. It is difficult to draw broad conclusions regarding a definitive target zone for cup positioning in THA, due to variability between studies and the likely multifactorial nature of THA dislocation. Future studies comparing cup positioning and dislocation rate should investigate surgical approach separately. Standardized tools for measurement of cup positioning should be implemented to allow comparison between studies.
| S-EPMC5251254 | biostudies-literature
Project description:Background Accurate acetabular cup orientation is associated with decreased revision rates and improved outcomes of primary total hip arthroplasty. This study assesses surgeon’s ability to estimate both the acetabular component inclination and anteversion angles via intraoperative fluoroscopy (IF) images. Methods We surveyed orthopedic surgeons to estimate acetabular component inclination and anteversion based on 20 IF images of total hip arthroplasty through a direct anterior approach. Postoperative computed-tomography scans were used to calculate the true inclination and anteversion component angles. The absolute difference between the true and estimated values was calculated to determine the mean and standard deviation of the survey results. Interrater reliability was determined through interclass correlation coefficients. Results A majority of surgeons preferred the direct anterior approach (83.3%) and utilized IF during surgery (70%). Surgeons surveyed were on average 5.9° away from the true value of inclination (standard deviation = 4.7) and 8.8° away from the true value of anteversion (standard deviation = 6.0). Respondents were within 5° of both inclination and anteversion in 19.7% of cases, and within 10° in 57.3% of cases. All surgeons were determined to have poor reliability in estimating anteversion (interclass correlation coefficient < 0.5). Only 2 surgeons were determined to have moderate reliability when estimating inclination. Conclusions Surgeons, when solely relying on IF for the estimation of anteversion and inclination, are unreliable. Utilization of other techniques in conjunction with IF would improve observer reliability.
| S-EPMC10018435 | biostudies-literature
Project description:The dynamic orientation of total hip replacement acetabular cups during walking may vary substantially from their assumed position at surgical implantation and may vary between individuals. The scale of this effect is of interest for both pre-clinical device testing and for pre-operative surgical planning. This work aimed to evaluate (1) patient variation in dynamic cup orientation; (2) whether walking speed was a candidate proxy measure for the dynamic cup orientation; and (3) the relationships between dynamic cup orientation angles and planar pelvic angles. Pelvic movement data for patients with fast (20 patients) and slow (19 patients) self-selected walking speeds were used to calculate acetabular cup inclination and version angles through gait. For aim 1, the range and extremes of acetabular cup orientation angles were analysed for all patients. A large patient-to-patient variation was found in the ranges of both inclination angle (1° to 11°) and version angle (4° to 18°). The version angle was typically retroverted in comparison to the implantation position (greatest deviation 27°). This orientation is substantially different to the static, 0° version, simplifying assumptions in pre-clinical 'edge loading' testing. For aim 2, the cup orientation angles were compared between the fast- and slow-walking groups using statistical parametric mapping. The only significant differences observed were for cup version angle, during ~12% of the gait cycle before toe-off (p < 0.05). Therefore, self-selected walking speed, in isolation, is not a sufficient proxy measure for dynamic acetabular orientation. For aim 3, correlations were recorded between the acetabular cup orientation angles and the planar pelvic angles. The cup inclination angle during gait was strongly correlated (Spearman's coefficient -1) with pelvic obliquity alone, indicating that simple planar assessment could be used to anticipate inclination angle range. The cup version angle was correlated with both pelvic rotation and tilt (Spearman's coefficient 0.8-1), indicating that cup version cannot be predicted directly from any single pelvic movement. This complexity, along with the interaction between inclination angle and range of version angle, supports the use of computational tools to aid clinical understanding.
| S-EPMC10885924 | biostudies-literature
Project description:Given the long-term problem of polyethylene wear, medical interest in the new improved cross-linked polyethylene (XLPE), with or without the adding of vitamin E, has risen. The main aim of this study is to gain further insights into the mutual effects of radiation cross-linking and addition of vitamin E on the wear performance of ultra-high-molecular-weight polyethylene (UHMWPE). We tested four different batches of polyethylene (namely, a standard one, a vitamin E-stabilized, and two cross-linked) in a hip joint simulator for five million cycles where bovine calf serum was used as lubricant. The acetabular cups were then analyzed using a confocal profilometer to characterize the surface topography. Moreover; the cups were analyzed by using Fourier Transformed Infrared Spectroscopy and Differential Scanning Calorimetry in order to assess the chemical characteristics of the pristine materials. Comparing the different cups' configuration, mass loss was found to be higher for standard polyethylene than for the other combinations. Mass loss negatively correlated to the cross-link density of the polyethylenes. None of the tested formulations showed evidence of oxidative degradation. We found no correlation between roughness parameters and wear. Furthermore, we found significantly differences in the wear behavior of all the acetabular cups. XLPEs exhibited lower weight loss, which has potential for reduced wear and decreased osteolysis. However, surface topography revealed smoother surfaces of the standard and vitamin E stabilized polyethylene than on the cross-linked samples. This observation suggests incipient crack generations on the rough and scratched surfaces of the cross-linked polyethylene liners.
| S-EPMC5873012 | biostudies-literature