The Effectiveness Of Postoperative Immobilization And Early Passive Motion On Shoulder Rotator Cuff Healing In Rabbit

Rotator cuff retear is a common complication after surgery. The incidence ranges from20%to90%. The primary factor for shoulder function recovery is rotator cuff integrity. However, tendon and bone are hard to heal, thus to preserve the integrity is also a major concern in postoperative rehabilitation. The purpose of postoperative rehabilitation should serve the tendon bone healing as well as shoulder range of motion recovery at the same time. That is why the effectiveness of postoperative passive motion on rotator cuff healing is controversial, and the timing for passive motion remains unclear. Therefore, the present study described and discussed the effectiveness of postoperative immobilization and early passive motion on rotator cuff healing and postoperative range of motion recovery. And our investigation revealed that postoperative immobilization could shorten the period of inflammation; meanwhile eliminate the fibroblast proliferation so as to improve the tendon-bone conjunction biomechanical properties. On the other hand, the early postoperative motion do no harm on the tendon bone conjunction while do not improve the shoulder range motion. The findings of the present study to provided more evidence in clinical workouts. PartⅠ The Effectiveness of Immobilization on Shoulder Rotator Cuff Healing in RabbitObjective To describe how postoperative immobilization effects on the rotator cuff healingMethod Supraspinatus injury was created and repaired in66New Zealand rabbits, afterwards they were randomly separated into two groups:(1) Non-immobilization (NI, n=33),(2) Continuous immobilization (IM, n=33). At the time point of3,6,12 weeks postoperatively, five rabbits of each group were sacrificed to have the histologic testing, biomechanical testing, and Magnetic Resonance Imaging. And at12week, shoulder abduction and external rotation angles will be evaluated under X ray.Result The histological examinations showed progressive healing in all the experimental groups. At3week, hyper cellular and hyper vascular were presented in both groups with non-immobilization group presenting more severe inflammation reaction. At6week, immobilization groups presented vivid proliferation of chondroblastoma and osteoblast while non-immobilization group had more fibroblasts proliferated. At12week, mature chondrocytes were aligned in immobilization groups but scar was formed in non-immobilization group. MRI imaging showed progressive healing for both groups however less surrounding tissue edema was presented in the immobilization group. The Signal/Noise Quotient (SNQ) of tendon-bone conjunction area showed that non-immobilization group was significantly higher than immobilization group at all the time points (3week:NI:7.59+0.82, IM:3.69±0.35, p<0.05。6week:NI:9.05±0.11, IM:4.04±0.22, p<0.05;12week:NI:27.54±4.6, IM:22.1±1.9, p=0.449). At12week, the failure load in immobilization group was significant higher than non-immobilization group (IM>NI, p<0.05), and tensile strength performed better in immobilization group (IM>NI, p<0.05). No difference was found between experimental groups for postoperative range of motion. Abduction angles were lower than normal but external rotator was close to the normal range of motion.Conclusion Immobilization resulted better histologic manifestation, biological properties, and MR findings than non-immobilization. Postoperative immobilization can improve rotator cuff healing while do no harm on external rotation angle. Part Ⅱ The Effectiveness of Immobilization Concomitant with Passive Motion on Rotator Cuff Healing in RabbitObjective To identify the effectiveness of postoperative immobilization concomitant with passive motion on rotator cuff healingMethod Supraspinatus injury was created and repaired in66New Zealand rabbits, afterwards they were randomly separated into two groups:(1) Non-immobilization (NI, n=33),(2) Immobilization concomitant with passive motion (IP, n=33). At the time point of3,6,12weeks postoperatively, five rabbits of each group were sacrificed to have the histologic testing, biomechanical testing, and Magnetic Resonance Imaging. And at12week, shoulder abduction and external rotation angles will be evaluated under X ray.Result The histological examinations showed similar manifestation in both groups. At3week, hyper cellular and hyper vascular were presented at tendon-bone interface. At6week, there was vivid proliferation of chondroblastoma and osteoblast and at12week, mature chondrocytes were aligned. MRI imaging showed progressive healing for both groups. The Signal/Noise Quotient (SNQ) of tendon-bone conjunction area showed that non-immobilization group was significantly higher than immobilization group at all the time points (3week:IM:3.69±0.35, IP:4.02±0.15, p=0.462.6week:IM:4.04±0.22IP:4.43±0.04, p=0.513;12week:IM:22.1±1.9, IP:23.1±3.2, p=0.644). At12week, all biomechanical parameters showed no difference between experimental groups. No difference was found between experimental groups for postoperative range of motion. Abduction angles were lower than normal but external rotator was close to the normal range of motion.Conclusion Immobilization concomitant with passive motion did no harm on tendon bone conjunction while not improve shoulder range of motion.