A reabsorbable tubular chamber for the treatment of large diaphyseal bone defects. Experimental study in rabbits.

Twenty-five rabbits were used to test the healing of diaphyseal defects by means of a reabsorbable tubular chamber In 20 animals a 10 mm gap was created in the left radius and bridged with a poly-L-lactide chamber (experimental side). The same defect was created on the right radius, remaining untreated (control side). In the remaining 5 animals, the right radius was left intact and they were used only for biomechanical tests at 12 months. X-rays and histomorphometry showed no bone repair at the control side while the inner surface of the chamber was progressively lined by neoformed bone (75% of the normal cortical thickness). Biomechanical data demonstrated that elastic modulus and ultimate stress were not significantly different in both experimental and intact radii. The chamber, by preventing the passage of soft tissues and creating a dose space for intrinsic repair factors, seems to be a suitable device for the repair of long bone defects

Osteogenic protein-1 associated with mesenchymal stem cells promote bone allograft integration.

Limited incorporation and modest bone remodeling can cause allograft failure. We investigated whether mesenchymal stem cells (MSCs) and osteogenic protein-1 (OP-1) can improve allograft integration. A 3-cm full-size intercalary bone defect was created in the mid-diaphysis of the metatarsal bone of the sheep and it was replaced with an allograft alone (control group), or with MSCs (MSC group), OP-1 (OP-1 group), or MSCs and OP-1 (MSC+OP-1 group). Radiographic results showed a faster and complete integration of the allograft in the MSC+OP-1 group. Histology demonstrated that the amount of new bone was significantly greater inside the graft and a longer vessel penetration in the MSC+OP-1 group than in others. Mechanical strength of the allograft was not compromised by the high rate of bone remodeling. These results demonstrated that the association of MSCs and OP-1 improve bone allograft integration promoting an almost complete bone restoring