[Application of acetabulum reinforcement ring for reconstructing acetabular defects in artificial hip replacement].

OBJECTIVE: To study the operative methods and therapeutic effects of acetabulum reinforcement ring in the reconstruction of acetabular defects in primary and revisional artificial hip replacement.

METHODS: From November 2000 to July 2005, 14 cases (15 hips) of severe acetabular defects in artificial hip replacement were treated with acetabulum reinforcement ring combined autogenous or allogenic bone transplantation, including 7 males and 8 females aged 34-72 years with an average of 55 years. Among them, 9 cases (9 hips) underwent artificial hip joint revision, which was 3-22 years (average 8.9 years) far away from their primary replacement, and 5 cases (6 hips) received primary replacement, including 1 case of rheumatoid arthritis of both hips, 1 osteoarthritis caused by acetabular dysplasia, 1 femoral head resection due to debridement of hip infection, 1 nonunion of acetabulum old fracture with the center dislocation of femoral head and 1 old acetabulum fracture. The disease course was 2-25 years (average 11.6 years). According to the American Academy of Orthopaedic Surgeons (AAOS) classification, the acetabulum defects of 7 hips were categorized into Type II, 6 hips were Type III and 2 hips were Type IV. Harris score was (59.1 +/- 15.4) points preoperatively.

RESULTS: All wounds were healed by first intention. The symptom of sciatic nerve simulation was occurred in 1 case and was relieved after taking neuroprotective drug for 5 months. All the cases were followed up for 33-90 months (average 51.3 months). Harris score at the final follow-up was (81.9 +/- 10.4) points, indicating there was a significant difference between before and after operation (P < 0.01). X-ray film demonstrated that the displacement of acetabulum reinforcement ring and acetabular cup was less than 5 mm, the rotation was less than 5 degrees, and there was no progressive radiolucent zone around acetabulum and screw.

CONCLUSION: Acetabulum reinforcement ring is beneficial to reconstruct severe acetabular defects, improve hip joints' function and provide primary stability for putting acetabular cup into an ideal biomechanical position.