Femoral head necrosis in renal transplanted patients. Evidence of a haemodynamic etiological factor

Aseptic necrosis of bone following renal transplantation. Clinical and biochemical aspects and bone morphometry

Aseptic necrosis of bone has developed 5--48 months (mean 23) after renal transplantation in 22 (11%) of 195 patients with graft function for more than 6 months. The bone lesions were mainly localized to weight-bearing cancellous bone areas, most often the femoral heads. The mean duration of hemodialysis was significantly longer in recipients with aspetic necrosis than in those without. The serum concentration of phosphate was reduced and the serum concentration of parathyroid hormone increased in both groups of recipients. Quantitative histological examination of iliac crest biopsies showed a pronounced reduction of spongy bone (osteopenia) in recipients with aseptic necrosis compared with both normals and recipients without aseptic necrosis. Both patient groups showed similar changes in bone remodelling, indicating decreased bone formation. These findings suggest that osteopenia is an important contributory factor in the development of aseptic necrosis of bone after transplantation. The osteopenia may be a consequence of both the uremic bone disease before transplantation and the immunosuppressive treatment after transplantation.

Osteonecrosis and fractures following renal transplantation

Skeletal radiological surveys in 161 renal transplant recipients identified 36 patients with 115 lesions of osteonecrosis. A further two patients with osteonecrosis found at autopsy had had no radiographic abnormality. The total incidence of osteonecrosis was, therefore, 38 (24%) out of 161. The lesions were frequently multiple and bilateral with structural failure being the most common initial abnormality and the femoral head the most frequent site. Lesions also occurred in the femoral condyles, the talus, the humeral heads and the metatarsals, many being symptom-free. Calcification was demonstrated in the femoral and tibial shafts. The initial radiological abnormality appeared at a mean interval of 19 months after transplant but could occur as late as 75 months. Significantly fewer patients, three (7%) out of 41, developed osteonecrosis following a low-dose prednisolone regimen (0.8 g) compared with a high-dose group (2.8 g) where 35 (29%) out of 120 were affected. More females than males developed osteonecrosis, but no correlation could be demonstrated with regard to age, primary renal disease, number and type of transplant and duration of dialysis prior to transplant. Osteonecrosis is a complication which can be reduced with a low-dose prednisolone regimen. Most lesions will be demonstrated by radiological survey undertaken during the second and fourth years after transplantation.

Skeletal complications following renal transplantation

The occurrence of skeletal complications was examined in a series of 204 renal graft recipients who had maintained graft function for more than 12 months. Osteonecrosis was observed in 22 of the patient (11 per cent) from 5 to 46 months after the transplant operation. The lesions were often multifocal, with as many as 40 joints affected. The most common site was the femoral head, necrosis of which was recorded in 24 instances. The lesions here present a major clinical problem, and total hip replacement was deemed necessary in 4 cases, in all of which an excellent result was achieved. Fractures had occurred after the transplantation in 53 patients (26 per cent), against only 6 before the operation. A total of 109 fractures had been sustained after periods ranging from 1 to 58 months, the most common site being the pelvic bones. The fractures were treated according to standard principles; no complications were encountered. The skeletal complications were equally common among the males and females; they tended to occur at advanced ages. They occurred to roughly the same extent whether the graft was from a related or a cadaveric donor and whether the patient had received one or more grafts.