Factors influencing the longer-term survival of uncemented acetabular components used in total hip revisions.

BACKGROUND: There are few longer-term follow-up reports of the results and complications of the use of cementless acetabular components in revision hip arthroplasty. In this study, we analyzed the clinical and radiographic results to determine the factors that affect longer-term survival of titanium-fiber-metal-coated acetabular components.

METHODS: During a fourteen-year period, one surgeon performed 211 consecutive unselected cementless acetabular revisions in 194 patients with a mean age of sixty-two years. The same technique was used for all revisions: the component was impacted and was fixed with multiple screws, and bone deficiencies were augmented with supplemental bone graft. Both the acetabular and the femoral components were revised in 142 hips, whereas an isolated acetabular revision was performed in sixty-nine hips. All 211 revisions were included in a survivorship analysis to twelve years. Prospectively determined clinical results in 135 hips and radiographic results in 131 hips were available at a minimum of five years postoperatively.

RESULTS: Seven acetabular components were removed: three, because of infection; one, because of recurrent dislocation; and three, because of mechanical loosening. There was asymptomatic radiographic loosening of one additional acetabular component, for a total rate of aseptic loosening of 2%. The twelve-year prosthetic survival rate was 95% (95% confidence interval, 91% to 99%), with failure defined as component removal for any reason. There was no significant difference in the rate of survival of the cup or femoral component between the sixty-nine hips treated with isolated acetabular revision and the 142 hips in which both components were revised. There was a significant difference in the rate of dislocation between the hips treated with isolated acetabular revision (dislocation in fourteen hips, 20%) and those in which both components had been revised (dislocation in eleven hips, 8%; p = 0.03), but there was no difference in component survival if a dislocation occurred. There was a significant association between a patient weight of >82 kg and acetabular failure (p = 0.04).

CONCLUSIONS: This titanium-fiber-metal-coated hemispheric component fixed with multiple screws had a twelve-year survival rate of 95% when used in an unselected, consecutive series of acetabular revisions. The rate of dislocation was significantly higher in the patients treated with isolated acetabular revision, and routine postoperative bracing is now recommended for that group.