Modular insert exchange in knee arthroplasty for treatment of wear and osteolysis.

UNLABELLED: Wear and osteolysis have been successfully treated by modular polyethylene exchange in revision hip arthroplasty. However, studies of the same approach in revision knee arthroplasty have not provided similar results. We evaluated the results of isolated polyethylene exchange for wear and/or osteolysis in 68 press-fit condylar TKAs from four centers. At a minimum of 24 months after polyethylene exchange surgery (average, 44 months; range, 24-83 months), there were 11 failures (16.2%). Failures included aseptic loosening in 10 knees and infection in one. With the relatively small cohort size we were unable to identify factors that predicted which knees were more likely to fail: we observed no correlation between failure and patient demographics, component design, or use of cement versus bone graft augmentation. Radiographic review demonstrated no progression of osteolytic lesions in 97% of knees in the study. While the short-term followup limits the conclusions, we believe the 84% success rate with modular polyethylene exchange for wear and osteolysis and the lack of progression of osteolytic lesions in the majority of the knees are encouraging. Full revision of well-fixed total knee components can lead to substantial bone loss, particularly in the face of osteolysis and we therefore consider modular polyethylene exchange in press-fit condylar knees a reasonable option for wear and osteolysis. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence

Total hip arthroplasty in patients with dwarfism.

BACKGROUND: Patients with short stature and osseous deformities resulting from osteochondrodysplasia frequently have premature development of advanced degenerative disease of the hip and thus may require total hip arthroplasty. The outcome of total hip arthroplasty in this group of young patients is unknown. In this study, we evaluated the long-term clinical and radiographic outcomes of total hip arthroplasty in patients with osteochondrodysplasia. METHODS: Between 1971 and 1997, sixty-two total hip arthroplasties were performed at our institution in thirty-seven patients with severe osteoarthritis secondary to osteochondrodysplasia. There were seventeen female patients and twenty male patients. Their average height was 142 cm, and their average age at the time of the index arthroplasty was thirty-seven years. The patients were followed clinically with use of the Harris hip score for a mean of 12.8 years, and they were followed radiographically for a mean of 11.5 years. RESULTS: The mean Harris hip score improved significantly (p < 0.0001), from 57 points preoperatively to 87 points at the time of the latest follow-up. Of the sixty hips available for follow-up, eighteen (30%) had required revision arthroplasty: fourteen required it because of aseptic loosening of one or both components; two, because of deep infection; one, because of periprosthetic fracture; and one, because of extensive osteolysis. There were two additional periprosthetic femoral fractures, which were treated with open reduction and internal fixation with retention of the components. The majority of patients had other functionally limiting conditions, such as spinal deformities, in addition to the degenerative arthritis. CONCLUSIONS: There was a high prevalence of complications, periprosthetic fractures, and mechanical failure in these patients with osteochondrodysplasia who underwent total hip arthroplasty. Young age, severe deformity, and multiple joint involvement may in part explain these findings. Nonetheless, total hip arthroplasty proved to be reliable for alleviating pain and improving function in patients with advanced symptomatic arthritis of the hip secondary to osteochondrodysplasia.