Hip-shelf procedure in the treatment of osteonecrosis of the transpositioned acetabulum after rotational acetabular osteotomy.

Necrosis of the transpositioned acetabulum after rotational acetabular osteotomy (RAO) is a major complication characteristic of this procedure. This complication, although rare, has been thought difficult to treat. We report a patient with acetabular osteonecrosis and subsequent collapse after RAO that was effectively treated with a shelf operation, providing satisfactory remodeling of the hip joint. A 16-year-old female had undergone RAO for the treatment of developmental acetabular dysplasia. Postoperative radiography showed that the osteotomized acetabular fragment was unusually thin, and that the osteotome entered the hip joint during the surgery. Five months after the RAO, X-rays revealed significant collapse of the transpositioned acetabulum, and femoral head subluxation caused by postoperative osteonecrosis. Seven months after the RAO, the patient underwent a hip-shelf procedure. The remaining acetabular fragment was used in this procedure, according to the Spitzy method. Seven years after the second operation, favorable remodeling of the hip joint was observed; however, early osteoarthritic changes, including slight joint space narrowing, bone sclerosis of the new acetabulum, and bone cysts within the femoral head, were seen.

Expression of keratan sulfate at the arthroplasty surface after cup arthroplasty.

Fibrous tissue which regenerated on the acetabular arthroplasty surface was obtained from a 52-year-old woman who underwent total hip replacement after cup arthroplasty. The histological features of this newly formed fibrous tissue and expression of keratan sulfate, which is a characteristic matrix component of articular cartilage, were studied. Microscopic observation revealed that the arthroplasty surface consisted mainly of fibrous tissue which did not show metachromasia with toluidine blue staining, but there were many nodular structures communicating with the bone marrow. Immunostaining for keratan sulfate revealed clear positive staining around the cells of the nodular structures communicating with the bone marrow, while only weakly positive staining was observed in the superficial layer of the loose fibrous tissue. The present study revealed marked formation of articular cartilaginous tissue in areas having good communication with the bone marrow, which indicates that maintenance of this communication may be necessary to improve the outcome of cup arthroplasty.

Hyaluronan in synovial fluid of patients with loose total hip prosthesis. Comparison with hyaluronan in patients with hip osteoarthritis and idiopathic osteonecrosis of femoral head.

The concentration and molecular weight of hyaluronan (HA) in the synovial fluid of the hip joint were determined in 13 patients (aged 62.8 +/- 9.4 years) who had undergone prior total hip arthroplasty(THA), 23 patients (aged 65.0 +/- 8.2 years) with osteoarthritis of the hip joint (OA), and 13 patients (aged 40.2 +/- 2.7 years) with idiopathic osteonecrosis of the femoral head (ION). A sample of synovial fluid was obtained during revision THA because of loosening of the total hip prosthesis for the THA group, and during the first replacement surgery or osteotomy for the OA and ION groups. The concentration of HA in the synovial fluid was 0.64 +/- 0.42 mg/ml in the THA group, 1.07 +/- 0.28 mg/ml in the OA group, and 1.30 +/- 0.56 mg/ml in the ION group. The concentration of HA in the synovial fluid of the THA patients was significantly lower than that of the OA and ION patients (P = 0.0156 vs OA, P = 0.003 vs ION). The molecular weight of HA was 309 +/- 88.3 x 10(4) Da in the THA group, 377 +/- 201 x 10(4) Da in the OA group, and 240 +/- 148 x 10(4) Da in the ION group; these values do not differ significantly (P = 0.259 vs OA, P = 0.174 vs ION). Among the THA patients, there was no relation between the concentration of HA and the age of the patient, length of time since the first operation, or type of prosthesis fixation; there was also no relation between the molecular weight of HA and each of these factors. These results suggest that a pseudosynovial membrane is regenerated after THA, and that it produces HA of the same molecular weight as that in patients with OA and ION, although in smaller quantities.