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Porous-coated anatomic acetabular component possibly less durable than femoral component for THA
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Compared with a porous-coated anatomic femoral component, the acetabular component was found to be less durable, with annual polyethylene wear rate, size and abduction angle responsible for failure, according to study results.
Researchers reviewed data for 113 patients with osteoarthritis of the hip who underwent 136 porous-coated anatomic total hip arthroplasties (THA) between 1986 and 1997. At final follow-up, data were available for 60 hips. The researchers used the Harris Hip Score preoperatively and at 1, 5, 10, 15 and 20 years postoperatively to clinically assess surviving patients. Mean follow-up was 15.2 years.
Although results showed an improvement in mean Harris Hip Score from 45 points preoperatively to 95 points 1 year postoperatively, scores decreased to 90 points at 10 years, 85 points at 15 years and 78 at 20 years postoperatively.
After a mean of 13.9 years, 12 acetabular components were revised. In the survival group, the researchers found an abduction angle of 38.9° vs. 45.8° in the revision group.
Ten femoral components were revised after a mean of 13 years. The researchers found a satisfactory stem fill in 30 of the 60 stems, with an average filling ratio of medullary canal by the stem in the coronal plane of 80.1% in stem survival cases and 71.5% in revision cases.
After 10 years, results showed a survival rate of 100% for both acetabular and femoral components; however, at 15 years, postoperative survival rate was 77% for the acetabular component and 85% for the femoral component. At 23 years postoperatively, survival rate was 60% for the acetabular component and 82% for the femoral component. Overall survival rate was 52% at 23 years postoperatively, according to the researchers.
Univariate regression showed revision surgery was significantly associated with acetabular component size and abduction angle and annual polyethylene wear rate, as well as size of the femoral component, filling ratio of the femur and annual polyethylene wear rate. Multivariate regression showed acetabular component revision surgery was significantly associated with acetabular component size and abduction angle and annual polyethylene wear rate, whereas femoral component revision surgery was significantly associated with filling ratio of the femur and annual polyethylene wear rate.
Disclosure: Inaba is on the speakers bureau for Smith & Nephew and Stryker Orthopaedics.
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Tezuka T. J Arthroplasty. 2014;doi:10.1016/j.arth.2013.11.015.
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