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Radiostereometric analysis (RSA) is an accurate and precise measurement tool of migration and rotation of implants. We investigated if early migration measured with RSA can be used to predict the risk of later aseptic loosening in acetabular revision surgery.~Introduction~Background~A total of 312 patients who underwent acetabular revision surgery were followed by RSA measurements for 2 to 20 years. The endpoint was either re-revision due to aseptic loosening or loosening on last available radiographic examination. Cox regression model was used to evaluate the predictive value of early migration.~Patients and Methods~Methods~A total of 16 acetabular cups were re-revised due to aseptic loosening and 7 unrevised cups were radiographically loose. Every mm of proximal migration 2 years postoperatively increased the risk of aseptic loosening by 37% (hazard ratio (HR) 1.37, 95% confidence interval (CI) 1.18-1.58). Adjusting for differences in base line demographics, bone defects and surgical techniques in a Cox regression model, risk of aseptic loosening with every mm of proximal migration was even higher (HR 1.94, 95% CI 1.34-2.82, p<0.001).~Results~Results~We found a strong relationship between early migration measured by RSA and risk of late aseptic loosening in acetabular revision surgery. Monitoring proximal migration with RSA should be considered as an essential step in quality assessment when new implants and novel techniques are introduced in acetabular revision surgery.~Conclusions~Conclusions [ABSTRACT FROM AUTHOR]

Background: A common claim in the orthopaedic literature is that acetabular dysplasia (AD) exists when the center-edge angle of Wiberg (CE angle) is <20 degrees and that AD leads to osteoarthritis (OA). Our purpose is to evaluate the validity of the linkage between AD and OA., Methods: We assess and discuss the theories and the empirical evidence relating AD to OA. Moreover, we test the rule that hips with a CE angle <20 degrees will develop OA by 65 years of age, by looking for exceptions to this rule., Results: Wiberg and Cooperman and colleagues present 30 ideal patients for assessing the relationship between AD and OA. Each was arthritis free, with stable AD, CE angle <20 degrees, without signs of subluxation. They were all followed and all developed OA. In the studies by Stulberg and colleagues, and Jacobsen and colleagues, every patient presented with OA, making it difficult to be certain about the appearance of the hip before the onset of OA. In the study by Murphy and colleagues, we have the same problem, as an unknown number of patients already had OA at first assessment. All of these studies used different schemes for diagnosing OA, making the studies difficult to compare. Most of the patients in the studies were of Northern European ancestry, making the results difficult to generalize to other populations. Four patients had CE angles <20 degrees and did not develop severe arthritis by 65 years of age., Conclusions: Our conclusions apply directly to patients of Northern European ancestry. A few patients with stable, mild AD (CE angle 15 to 19 degrees) will be arthritis free at 65 years of age. Almost all patients with stable AD develop OA by 65 years of age. Unstable AD (CE angle <20 degrees, with subluxation) always leads to OA by 65 years of age. It is probably reasonable to extend these conclusions to other populations, but the reader must be prepared to re-evaluate them, as more data accumulates.

Background and Purpose: Monoblock acetabular cups represent a subtype of uncemented cups with the polyethylene liner molded into a metal shell, thus eliminating-or at least minimizing-potential backside wear. We hypothesized that the use of monoblock cups could reduce the incidence of osteolysis and aseptic loosening, and thus improve survival compared to modular designs., Patients and Methods: We identified all 210 primary total hip arthroplasty (THA) procedures in the Swedish Hip Arthroplasty Register that used uncemented monoblock cups during the period 1999-2010. Kaplan-Meier and Cox regression analyses with adjustment for age, sex, and other variables were used to calculate survival rates and adjusted hazard ratios (HRs) of the revision risk for any reason. 1,130 modular cups, inserted during the same time period, were used as a control group., Results: There was a nearly equal sex distribution in both groups. Median age at the index operation was 47 years in the monoblock group and 56 years in the control group (p < 0.001). The cumulative 5-year survival with any revision as the endpoint was 95% (95% CI: 91-98) for monoblock cups and 97% (CI: 96-98) for modular cups (p = 0.6). The adjusted HR for revision of monoblock cups compared to modular cups was 2 (CI: 0.8-6; p = 0.1). The use of 28-mm prosthesis heads rather than 22-mm heads reduced the risk of cup revision (HR = 0.2, CI: 0.1-0.5; p = 0.001)., Interpretation: Both cups showed good medium-term survival rates. There was no statistically significant difference in revision risk between the cup designs. Further review of the current patient population is warranted to determine the long-term durability and risk of revision of monoblock cup designs.