OBJECTIVETo observe the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) in promoting the tendon-bone healing in rabbits after anterior cruciate ligament reconstruction.

METHODSThirty normal adult New Zealand rabbits were divided into 3 groups for anterior cruciate ligament reconstruction using autologous semitendinosus tendons as the graft material. In the rhBMP-2 group, fibrin glue (FG) containing rhBMP-2 was applied to the interface between the tendon graft and the bone tunnel, while in the FG control group, only FG was applied. The blank control group received no treatment after the surgery. The grafts were collected at 2, 4, 8 weeks after the surgery for gross observation and histological examination of the graft incorporation.

RESULTSIn the FG control group, the tendon-bone interface was filled with granulation tissue 2 weeks after the surgery, and the newly generated tissue growing into the bone tunnel and fibroblasts were observed at 4 weeks. Till week 8, Sharpey's fibers were found in the interface with the formation of indirect insertion. In the rhBMP-2 group, the tendon-bone interface was filled with cartilage tissue at 2 weeks, and the four-layer direct insertion was formed at 4 weeks; till week 8, the interface was mainly composed of the direct insertion.

CONCLUSIONrhBMP-2 can induce direct insertion formation in the tendon-bone interface after early anterior cruciate ligament reconstruction. The direct insertion possesses better biomechanical properties than indirect insertion.