Acetabular Revision Surgery with the Uncemented Oblong Bofor Cup - Early to Midterm Results

IntroductionFailure of acetabular components frequently leads to bone loss with extensive elongated defects in the surrounding bone. In these cases the use of an oblong cup has been described as an option for acetabular reconstruction. We report the longest follow up results obtained with this implant to date.Materials and MethodsA prospective study was conducted to evaluate the results of the BOFOR oblong revision cup. Between 2001 and 2006, 15 acetabular revisions were performed for aseptic loosening of the acetabular cup. The acetabular defects were classified as type 2A to 3A, according to Paprosky's criteria. No allografts were used in any of the cases. The mean follow-up was 90 months (range 60–120 months).ResultsClinical assessment at follow-up showed a significantly improved mean Harris Hip Score from 39 points preoperatively to 84 points postoperatively and a mean Oxford Hip Score from 55 points preoperatively to 22 points postoperatively. Only one case underwent re-revision due to aseptic loosening in a patient with severe ankylosing spondylitis. There were no cases of dislocation or infection. One patient had a sciatic nerve neurapraxia. After an average follow up of 7.5 years, 93% of the investigated implants remained in-situ without further revision.ConclusionThis study shows that the BOFOR cup provided good clinical results and showed satisfactory stability at early to midterm follow-up.