Introduction: New biological approaches to reconstruction of major bone deficiency such as the use of bone substitutes and growth factors are being developed. This paper reports on the adverse response to the Bioglass in comparison to allograft alone.

Aim: To compare the biological response to femoral impaction grafting and a cemented femoral stem when using allograft bone versus allograft bone plus a synthetic bone graft substitute, Bioactive glass.

Methods: Eighteen merino wethers underwent a left cemented hemi-arthroplasty and were randomised to have impaction allografting of the femur using either allograft alone (allograft group) or a 50:50 mix of allograft and Bioactive glass (Bioglass group). After sacrifice at 12 weeks, histological analysis of the femora at the levels of the proximal, mid and distal femoral stem and distal to the stem was undertaken.

Results: In the allograft group, there was a consistent response with bone graft incorporation being greatest in the proximal femur and occurring progressively less, more distally. Mineralised bone apposition in the graft occurred post-operatively after eight weeks. In contrast, in the Bioglass group, the response was inconsistent. Bone graft incorporation was either minimal, or there was partial or complete resorption of the bone graft with replacement by particulate-laden fibrous tissue and resorption of endocortical bone. Inflammation of the capsule tissue was noted in some cases.

Conclusion: In comparison to allograft alone, the use of Bioglass to supplement allograft for use in impaction grafting in ovine hip arthroplasty gave inferior results.