To study bone morphogenetic protein(BMP)-induced osteogenesis of tendon graft and its effect on the healing of tendon-bone interface.

The model of tendon-bone healing was established in twenty-six adult New Zealand rabbits. Both tendon graft and tendon-bone interface were simultaneously treated with BMP in the experimental group, and the control group was only treated with normal saline. Twelve weeks after treatment, the animals were sacrificed and studied by gross anatomy, histomorphology and computer tomography(CT). The healing of tendon-bone interface in different groups was analysed by Student’s t test correspondingly.

Twelve weeks after treatment, the tendon graft within bone tunnel of experimental group became hard in texture and connected close to adjacent host bone. Especially, the calcified tendon graft integrated with host bone to some extent. With hematoxylin-eosin (HE)and Masson staining, it was found that the tendon-bone interface mainly consisted of fibrocartilage and Sharpey’s fibers in the BMP-treated group. New bone formed in both tendon graft and tunnel gap. In some place, the newly-formed trabecula connected closed to the host bone. However, there was mainly connective tissue present in the gap of control group. According to the histological scoring system, the BMP-treated group got higher scores(6.6±0.8) as compared to that of control group(2.7±0.7), the difference was statistical significant(t=13.361, P<0.01). With CT scanning, the higher signal of density was present in the bone tunnel of BMP-treated group(191±17) than that of control group(11±4), which indicated the osteogenesis of tendon graft within the host tunnel(t=31.591, P<0.01).

BMP is able to induce osteogenesis of tendon graft and this further enhances the healing of tendon-bone interface.