Abstract
Cup arthroplasty used to be performed for osteoarthritis of the hip in younger patients in order to preserve bone stock in our hospital. We report four cases of total hip arthroplasty (THA) after cup arthroplasties.
Case 1. The patient was a 51-year-old woman. She was diagnosed with osteoarthritis of the hip secondary to developmental dislocation of the hip (DDH) and underwent a left cup arthroplasty at the age of 23 years. Twenty-eight years later she underwent left THA. During the operation, it was very difficult to pull down the femur, and the procedure resulted in a distal femur fracture.
Case 2. The patient was a 62-year-old woman. She was diagnosed with osteoarthritis of the hip secondary to DDH and underwent a right cup arthroplasty at the age of 38 years. Twenty-four years later she underwent right THA. The formation of osteophyte in the acetabulum prevented dislocation of the femoral head. In situ osteotomy of the femoral neck was necessary.
Case 3. The patient was a 78-year-old woman. She was diagnosed with rheumatoid arthritis and underwent a left cup arthroplasty at the age of 49 years. Twenty-nine years later, she underwent left THA due to pain progression and leg length discrepancy. The weakness of the bone resulted in a fracture in the superior margin of the obturator foramen, resulting in the migration of acetabular reinforcement. She underwent a repeat operation.
Case 4. The patient was a 43-year-old man. He was diagnosed with post-traumatic osteoarthritis of the hip and underwent a right cup arthroplasty at the age of 31 years. Twelve years later, he underwent right THA.
In these four cases, THAs were performed on average 23 years after cup arthroplasties, and the Hip score, as defined by the Japanese Orthopaedic Society, improved from 41.8 points preoperatively to 71.3 points at the final follow-up. The features of patients who have undergone cup arthroplasty include a poor range of motion and leg length discrepancy due to migration of the cup. The problem is that surgeons have difficulty in pulling down the femur to deal with acetabular cavitary bone defects during the operation. It was very useful to use modular-neck stems and transplant the bone with acetabular reinforcements. In conclusion, we recommend that cup arthroplasties be converted to THAs before the cups migrate severely into the acetabulum.
