Effect of TGF-β1 and bFGF on tendon-to-bone healing after anterior cruciate ligament reconstruction with hamstring tendon autograft

Objective To investigate the effect of TGF-β1 and bFGF on tendon-to-bone healing after anterior cruciate ligament(ACL) reconstruction with hamstring tendon autograft. Methods A total of 48 healthy male New Zealand white rabbits, body weight 2.5-3.0 kg, were selected between January 2018 and December 2018 and divided into two groups in accordance with the random number table, with 24 in each group. ACL reconstruction with hamstring tendon autograft was performed in both groups. In group A, TGF-β1 and bFGF fibrin gel complexes were filled in the tendon-bone gap of the posterior hamstring tendon tunnel after transplantation; in group B, fibrin gel complexes were filled in the tendon-bone space of bone tunnel. The histological morphology and biomechanical properties of ACL transplanted in the two groups were observed at 4, 8 and 12 weeks after the operation, and the results were analyzed and compared. Results The results of histological examination: At 4 weeks after the operation, loose connective tissue was observed between the transplanted ligament and bone tunnel in both groups, and the collagen fibers began to form, which was more in group A as compared with group B. On W8 after the operation, the collagen fibers between the transplanted ligament and bone tunnel in the group A began to arrange in an orderly manner, and there were dense Sharpey fibers in the group B. On W12 after the operation, the ligaments in the group A began to arrange in an orderly manner. The structure of the endpoints was arranged orderly, the new fibrocartilage, calcified cartilage and osteocytes tended to mature, and the "tidal line" structure was seen dimly. The structure of the group B was still unclear. At each observation node after the operation, the new bone mass of the group A increased gradually, and at the same observation node was larger than that of the group B(all P<0.05). In mechanics, the results of ultimate tensile strength in groups A,and B were(72.69±5.09)N,(61.59±5.82)N respectively at 4 weeks,(83.00±5.24)N,(73.93±8.89)N respectively at 8 week,(102.39±6.42)N,(85.12±9.59)N respectively at 12 weeks, the load of the group A was significantly higher than that of the group B at each observation node, and the difference between the two groups was significant(all P<0.05). Conclusion TGF-β1 and bFGF can promote tendon-bone healing after ACL reconstruction with hamstring tendon autograft.