OBJECTIVETo study the effect of continuous passive motion (CPM) on basic fibroblast growth factor (b-FGF) expression during tendon-bone repair in rabbits and explore the role of stress in the postoperative repair after acute rotator cuff injury.

METHODSSixteen rabbits randomized into CPM group (n=8) and non-CPM group (n=8) were subjected to surgically induced acute rupture of the supraspinatus tendon and subsequent surgical repair, with another two rabbits serving as the control. Two weeks after the operation, the rabbits in CPM group underwent CPM training, and those in non-CPM group were normally fed only. At 2, 4, 6, and 8 weeks after the operation, 2 rabbits from each group were sacrificed and the tissue samples were obtained for detecting the changes in b-FGF expression.

RESULTSTwo weeks after the operation, b-FGF expression was detected in both groups, and the CPM group showed slightly higher and more diffusive expression. At 4 weeks, b-FGF expression was significantly higher and distributed over a greater area in CPM group and in the non-CPM group. A large number of fibroblasts positive for b-FGF expression were identified in CPM group, aligning in parallel with the tendon membrane. At 6 weeks, b-FGF in the CPM group showed no obvious changes but that in the non-CPM group became lightened. At 8 weeks, b-FGF expression was reduced in both groups, which was more obvious in the non-CPM group.

CONCLUSIONCPM can promote b-FGF expression to enhance type III collagen synthesis at the tendon-bone interface in early stage of tendon-bone repair following acute rupture of supraspinatus tendon in rabbits, thereby contributing to tendon-bone recovery after rotator cuff injury.