Rotational acetabular osteotomy with resection of the capital drop and double floor for advanced osteoarthritis of the hip.

Rotational acetabular osteotomy (RAO) is an established joint preservation technique for early stage osteoarthritis (OA). To extend the application of RAO for advanced OA with significant osteophyte formation, we added intraarticular procedures including removal of the double floor and the capital drop to create medialisation and better coverage of the femoral head.
The procedures were performed for seven joints with advanced OA. The average age of patients at surgery was 39 years. The follow-up periods ranged from five to 23 years. The capital drop was resected in five joints and both the capital drop and the double floor were removed in the other two joints.
The Japanese Orthopaedic Association Hip Score improved from 53 points before surgery to 69 at the latest follow-up. The range of flexion was decreased. The centre-edge angle, Sharp angle and acetabular head index were significantly improved. The femoral head was medialised 5 mm by surgery. Three joints (43%) showed progression of osteoarthritis. One joint (14%) needed replacement at seven years after RAO. Resection of the capital drop and curtain osteophyte with RAO improved joint congruity and medialisation of the femoral head, but decreased the range of motion of the joint due to increased bony coverage. Progression of degeneration of the joint is not preventable. We abandoned these procedures for advanced osteoarthritis of the hip joint especially in older patients who were suitable for replacement arthroplasty.