Evaluation of biocompatible osteoconductive polymer (BOP) as an osteconductive implant

Abstract

Bilateral defects made in the lateral subtrochanteric area of the proximal femur in 16 dogs received Biocompatible Osteoconductive Polymer (BOP) fiber (n = 16), autogenous cancellous bone from the proximal femur (n = 4) or proximal humerus (n = 7), or no treatment (n = 5). BOP block was attached extraperiosteally to the proximal humerus in 7 dogs.

Surgery sites were evaluated radiographically at 4 week intervals, and histologically 4, 8, 16, and 24 weeks postoperatively. Radiographic signs of bone healing were not observed in defects receiving BOP fiber. Control defects had radiographic signs of progressive bone ingrowth. Histologic evidence of bone formation was observed extending to but not incorporating BOP fibers. No connective tissue or bone ingrowth into BOP blocks was observed.

Control defects healed by ingrowth of cancellous bone during the first 12 weeks following surgery and reformation of the lateral cortical wall by week 24. Cancellous grafted defects healed more rapidly and more completely than untreated defects. Although the mean weight of cancellous bone harvested from the proximal femur (0.82 ± 0.22g) was Significantly less (p < 0.05) than that harvested from the proximal humerus (1.38 ± 0.29 g), there was no qualitative difference in bony healing of grafted defects based on histologic and radiographic assessment.

The results of this study indicate that BOP is not osteoconductive when used in subtrochanteric femoral defects or when placed extraperiosteally on the proximal humerus of normal dogs. This study also shows that the proximal femur can be safely used to provide moderate amounts of cancellous bone, with reharvesting from the same subtrochanteric donor Site possible after 12 weeks.