Vascular changes following hip arthroplasty. The femur in goats studied with and without cementation

We studied two groups of 6 adult female African pygmy goats, which received cemented or uncemented femoral endoprostheses in their right hip. One additional goat was used for in vivo angiography preoperatively and postoperatively. The blood supply to the proximal femur at a macroscopic level was not severed by the operation. Until the 6th postoperative week, the animals were killed at weekly intervals. Microangiography and fluorescence microscopy revealed that rapid revascularization of the metaphyseal trabecular bone in the vicinity of the implants occurred as early as the first postoperative week in both groups. However, in general, the revascularization of the bone around the uncemented prostheses occurred more rapidly, resulting in earlier bone remodeling when compared with the cemented group. Surprisingly, the apposition of periosteal bone was longer lasting and more intensive in the uncemented group, particularly at the metaphyseal level. We suggest that this phenomenon may be enhanced by mechanical stimuli; the restoration of function was delayed in the noncemented goats.