Restoration of tensile properties at tendon insertion to bone by a patellar tendon-tibia autograft: An experimental study with canine infraspinatus

A free patellar tendon-tibia autograft was performed to reconstruct a tendon insertion to bone of the canine infraspinatus. In this experimental study restoration of mechanical properties at tendon insertion to bone of the patellar tendontibia autograft was examined on 0, 42, and 84 postoperative days. Five dogs were used for each time point. Bone union occurred in all grafts by 6 postoperative weeks. The ultimate strength at the tendon insertion to bone recovered from 255.5 N on 0 day to 264.3 N and 439.3 N on 42 and 84 postoperative days, respectively. Stiffness recovered from 141.8 KN/m on 0 day to 201.8 KN/m and 226.3 KN/mN on 42 and 84 postoperative days, respectively. Our results demonstrate that patellar tendon-tibia autograft maintains excellent mechanical properties at tendon insertion to bone in the early healing period. This result suggests that transfer or free graft of tendons with attaching bone plug has a mechanical advantage for reconstruction of the rotator cuff, which may allow the patient to institute early postoperative mobilization.