Histological and immunohistochemical analysis of an allogenic bone graft engineered with autologous bone marrow mononuclear cells in the treatment of a large segmental defect of the ulna. A case report.

The treatment of large (6 cm) segmental bone defects, especially in areas associated with soft tissue damages and exposure, is challenging. Massive bone allografts are widely used in reconstructive surgery to replace missing bone parts such as critical size defects, nevertheless, early vascular invasion is a critical factor in bone allograft incorporation and in the consequent success of the surgery. Unfortunately, it has been proven that only slow and incomplete bone integration is possible by using frozen allografts in the treatment of large bone defects. An allogenic frozen bone graft was engineered with bone marrow mononuclear cells (BMMCs) to repair a large ulna defect in a male patient. When infection and sinus developed at the graft site 4 months after implantation, the partially reabsorbed graft was removed and send to the lab for examination. The histological and immunohistochemical analysis performed on a graft removed from the central zone of the defect demonstrated areas of neo-vascularisation, indicating that a remodelling process was actively occurring even in an area not usually repopulated with the conventional techniques. For these reasons, we may hypothesise that the use of BMMCs has a role in the re-building of large segmental defects.