Minimum 5-Year Follow-up of Articular Surface Replacement Acetabular Components Used in Total Hip Arthroplasty

The articular surface replacement (ASR) monoblock metal-on-metal acetabular component was recalled due to a higher than expected early failure rate. We evaluated the survivorship of the device and variables that may be predictive of failure at a minimum of 5-year follow-up. A single-center, single-surgeon retrospective review was conducted in patients who received the DePuy Synthes ASR™ XL Acetabular hip system from December 2005 to November 2009. Mean values and percentages were calculated and compared using the Fisher's exact test, simple logistic regression, and Student's t-test. The significance level was P ≤ .05. This study included 29 patients (24 males, 5 females) with 32 ASR™ XL acetabular hip systems. Mean age and body mass index (BMI) reached 55.2 years and 28.9 kg/m², respectively. Mean postoperative follow-up was 6.2 years. A total of 2 patients (6.9%) died of an unrelated cause and 1 patient was lost to follow-up (3.4%), leaving 26 patients with 28 hip replacements, all of whom were available for follow-up. The 5-year revision rate was 34.4% (10 patients with 11 hip replacements). Mean time to revision was 3.1 years. Age (P = .76), gender (P = .49), BMI (P = .29), acetabular component abduction angle (P = .12), and acetabulum size (P = .59) were not associated with the increased rate for hip failure. Blood cobalt (7.6 vs 6.8 µg/L, P = .58) and chromium (5.0 vs 2.2 µg/L, P = .31) levels were not significantly higher in the revised group when compared with those of the unrevised group. In the revised group, a 91% decrease in cobalt and 78% decrease in chromium levels were observed at a mean of 6 months following the revision. This study demonstrates a high rate of failure of ASR acetabular components used in total hip arthroplasty at a minimum of 5 years of follow-up. No variable that was predictive of failure could be identified in this series. Close clinical surveillance of these patients is required.