Acetabular revision surgery with the uncemented oblong BOFOR Cup--early to midterm results.

INTRODUCTION: Failure 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 METHODS: A 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). RESULTS: Clinical 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. CONCLUSION: This study shows that the BOFOR cup provided good clinical results and showed satisfactory stability at early to midterm follow-up.

The precision and accuracy of templating the size of unicondylar knee arthroplasty.

In trauma and joint arthroplasty, preoperative templating is an important step that can help in the selection of implant size, position and alignment. Although the precision (reproducibility) of templating in unicondylar knee arthroplasty has been assessed previously, the accuracy has never been studied. Our aim is to assess the precision and accuracy of using the templating system for one commonly used unicondylar knee arthroplasty, ALPHANORM design (Alphanorm Medizintechnik, Germany). Eight observers used the templating system to estimate the size of the unicondylar knee prosthesis ALPHANORM in 29 randomly selected patients with osteoarthritis. The observers, who all were orthopaedic surgeons with two different levels of experience, worked independently and repeated their measurements 2 weeks later. All the patients subsequently underwent unicondylar knee replacements, and the actual size of the femur and tibia was assessed intra-operatively without any knowledge of the template sizes. Our results revealed a high level of intra-observer reproducibility. However, the inter-observer reproducibility and the accuracy all were poor.