Summary
The semitendinosus tendon graft with intact tibial insertion in ACLR would bypass the graft avascular necrosis stage, which improves tendon-bone healing and biomechanical strength.
Abstract
Background
The semitendinosus tendon graft with intact tibial insertion has sustainable blood supply and might be beneficial for graft maturation following anterior cruciate ligament reconstruction (ACLR); however, its potential advantages for graft tendon-bone healing is still unclear.
Hypothesis
The intact tibial insertion of hamstring tendon can preserve enough blood supply to keep the harvested tendon alive, which can improve tendon-bone healing and biomechanical strength of the graft
Methods
Sixty-four healthy New Zealand white rabbits underwent unilateral ACLR with semitendinosus tendon autograft after random enrollment into two groups (Study group: thirty-two rabbits with semitendinosus tendons preserved tibial insertion. Control group: thirty-two rabbits with free semitendinosus tendons). At week 3, 6, 12, and 24 postoperative, 8 rabbits in each group were killed respectively to evaluate the tendon-bone healing by histological staining, micro-CT examination, and biomechanical test.
Results
The grafts in study group maintained similar cell count with no signs of necrosis or hypocellularity across all time points, but the grafts in control group underwent a characteristic stage of necrosis at week 3 and 6 postoperative. Sharpey-like fibers were observed from 3 weeks postoperative at tendon-bone interface in study group, and a normal-insertion-like structure was formed at week 12, which became more mature at week 24. While in control group, Sharpey-like fibers could not be observed until week 12 postoperative, and a normal transition through cartilage from bone to tendon was not observed at any time points. Histological scores of tendon-bone interface in study group were significantly higher than those in control group at week 6, 12, and 24 postoperative (P =0.04, 0.00, 0.04). Compared to the control group, the study group was shown on micro-CT to have a significantly smaller bone tunnel area at week 6 postoperative (P =0.01) and larger bone volume/total volume values at week 3 and 6 (P =0.00, 0.01). Also, the study group had a significantly higher failure load at week 12 and 24 (P=0.03, 0.03) and a significantly higher stiffness at week 24 (P=0.00) than the control group.
Conclusions
The semitendinosus tendon graft with intact tibial insertion in ACLR would bypass the graft avascular necrosis stage, which improves tendon-bone healing and biomechanical strength.
Clinical relevance:
It indicated that an alive graft in ACLR could improve tendon-bone healing and biomechanical strength of the graft, which might be beneficial to early and intensive rehabilitation after ACLR.