We analysed data from 155 revisions of identical cementless hip prostheses to determine the influence of patient-, implant-and surgery-related factors on the polyethylene wear rate and size of periprosthetic osteolysis (OL). This was calculated by logistic regression analysis. Factors associated with an increased/decreased wear rate included position of the cup relative to Kohler's line, increase in abduction angle of the cup, traumatic and inflammatory arthritis as a primary diagnosis, and patient height. Severe acetabular bone defects were predicted by an increased wear rate (odds ratio, OR=5.782 for wear rate above 200 mm 3 /y), and increased height of the patient (OR= 0.905 per each centimetre). Predictors of severe bone defects in the femur were the increased wear rate (OR=3.479 for wear rate above 200 mm 3 /y) and placement of the cup outside of the true acetabulum (OR=3.292). Variables related to surgical technique were the most predictive of polyethylene wear rate.

Background: Hydroxyapatite coated (HAC) hip implants have been used in clinical practice for more than two decades. However, the majority of studies have reported only intermediate term outcomes that are not reliable for predicting long-term behavior in all implants. The aim of this study was to determine the performance of HAC total hip arthroplasty in younger patients over a 10-year follow-up period. Methods and Results:This was an observational retrospective study of a 137 consecutive hips with the ABG I prosthesis. Of these, 128 were available for the last investigation. Median duration of follow-up was 10.9 years. The mean age at time of index surgery was 46±6.7 years. Probability of implant survival was estimated using the Kaplan-Meier method. The overall 12-year cumulative survival was 0.55 (95% CI, 0.443-0.659). Periprosthetic osteolysis (57 %) was the most frequent reason for failure followed by aseptic loosening (28 %). When only aseptic loosening was included in the analysis, the same fi gures for cup and stem were 0.873 (95% CI, 0.808-0.938) and 0.992 (95% CI, 0.976-1.0), respectively. Patients with a smaller cup size were those at high risk for revision due to wear-related complications (odds ratio, OR=4.3; 95% CI, 1.734-10.555).Conclusion: This study reports one of the poorest 12-year survivorship data for cementless acetabular component in the literature. The main reason for premature failure was osteolysis, strongly related to high wear rate of polyethylene.

Background:Polyethylene wear is considered a most important part of periprosthetic osteolysis development. Thus, its measurement is central to contemporary orthopaedics.Aims: The aim of this paper was to compare the accuracy of three radiographic techniques for wear measurement. Secondly, the influence of the abduction angle of the cup on measurement accuracy was investigated.Methods: Wear was measured manually in 80 patients by a single observer according to the Livermore, Charnley, and Dorr description. A multi-component statistical analysis was used to test the hypothesis that the Livermore technique was superior. In vitro data obtained from a Universal-type measuring microscope served as a gold standard.Results: In vitro measurements showed an average linear wear of 0.363 mm per year (0.000-0.939, SD 0.241) with a corresponding volumetric wear rate of 161 mm 3 per year (0-467, SD 118.2). The Livermore technique showed the least deviation from the optical reference standard and a superior position from the viewpoint of error analysis but the correlation coefficient was slightly less (r = 0.761) than for the Dorr and Charnley techniques (r = 0.795 and r = 0.778, respectively). In addition, the mean error of the Dorr method differed significantly from zero (p = 0.036). Overall, the Livermore technique was the most accurate method for polyethylene wear measurement regardless of the abduction angle of the cup.Conclusions: The Livermore technique performed manually was more accurate than the Charnley and Dorr methods. Nevertheless, we consider the Dorr technique an adequate tool for day-to-day wear measurements, mainly due to its simplicity.

BackgroundWe studied which factor could predict aseptic loosening in ABG I hip prosthesis with hydroxyapatite coating. Aseptic loosening and periprosthetic osteolysis are believed to be caused, at least in part, by increased polyethylene (PE) wear rate via particle disease. Based on it, increased PE wear rate should be associated with aseptic loosening regardless of the type of implant.MethodsWe analyzed data from 155 revisions of ABG I hip prostheses to examine the influence of patient, implant, surgery, and wear related factors on the rate of aseptic loosening at the site of the cup. This was calculated by stepwise logistic regression analysis. The stability of the implant and severity of bone defects were evaluated intraoperatively.ResultsWe found that men (odds ratio, OR = 5.6; p = 0.004), patients with Charnley class C (OR = 6.71; p = 0.013), those having more severe acetabular bone defects (OR = 4 for each degree of severity; p = 0.002), and longer time to revision surgery (OR = 1.51 for each additional year; p = 0.012) had a greater chance of aseptic loosening of the cup. However, aseptic loosening was not directly predicted by polyethylene wear rate in our patients.ConclusionSeverity of bone defects predicts the risk for aseptic loosening in ABG I cup. Factors potentially associated with the quality of bone bed and biomechanics of the hip might influence on the risk of aseptic loosening in this implant.