Vascularized orthotopic osteochondral transplantation of the canine proximal femur.

Osteochondral vascularized proximal femoral allografts were orthotopically transplanted in five adult beagles (four experimental and one control). The experimental animals were placed on 0.1 mg/kg of FK506 intravenously for 7 days, and then converted to 1.0 mg/kg orally. Biopsies of the femoral heads were taken at 3 weeks postoperatively and at 1-month intervals thereafter. The specimens were studied histologically with a hemotoxylin and eosin staining technique. Bone biopsies showed no microscopic evidence of rejection, and only minimal evidence of necrosis. Patency of the microvascular anastomosis was confirmed with bone scanning, using technitium 99m phosphate, arteriograms, and by Doppler flowmeter. All animals had an uneventful postoperative course, with achievement of full weight-bearing status by postoperative day 10, and normal activity by 1 month postoperatively. There were no infections or hip dislocations. One animal sustained a femoral neck fracture and was sacrificed at 4 months. At 6 months, the remaining animals were sacrificed. At necropsy, the experimental animals and the normal dog showed viable chondrocytes and osteocytes, with minimal bone necrosis. No dislocations or allograft rejections were observed. Based on this small series, a successful technique has been developed for orthotopic transplantation of a vascularized hip joint in a canine model.

Cementless femoral components should be made from cobalt chrome.

Before 1982, the authors performed 177 primary total hip arthroplasties using a single-sized, extensively porous-coated cobalt-chrome femoral prosthesis. The current status of 122 of these arthroplasties is known. Two femoral prostheses have been revised for late symptomatic loosening, 2 for stem fracture, and 1 for infection. From 1982 to 1984, 227 primary arthroplasties were performed using the same stem in multiple sizes. Of these cases, 171 are available for followup. One stem (0.6%) has been revised for symptomatic loosening. Large osteolytic femoral lesions (average size, 8.1 cm2) developed in 3 patients, associated with an unusually large amount of polyethylene wear of their acetabular components. These patients have been treated by exchange of the polyethylene liner within the porous-coated acetabular component and allografting of the osteolytic lesions. The femoral components were not exchanged because osteolysis had not eroded the integrity of the supporting bone-implant interface to a point where loosening occurred. Before 1987, 193 patients with loose femoral components were treated with revision total hip arthroplasty, also using an extensively porous-coated cobalt-chrome femoral stem of similar design. Ten (5.7%) patients have required rerevision of the femoral prosthesis. Six of these 10 rerevisions were performed because of symptomatic loosening. Ninety-three percent of the patients in the primary series had relief of their preoperative pain and have improved functional ability; 94.2% are satisfied with their results. In the revision series, 89.1% of the patients are free of pain and function better than preoperatively, and 89.6% are fully satisfied with their results.(ABSTRACT TRUNCATED AT 250 WORDS)