Biomechanical response to stress stimulation with different intensities during early repair period of acute rotator cuff injury / 中国组织工程研究

ABSTRACT

BACKGROUND:Continuing stress stimulation has been confirmed to promote repair of rotator cuff injury.This experiment attempts to fu rther quantify the intensity of stress stimulation in order to reach a better therapeutic effect in the entire process of rotator cuff injury repair.OBJECTIVE:To explore the biomechanical performance of stress stimulation with different intensities on repair of acute rotator cuffinjuryMETHODS:Sixteen male New Zealand rabbits were randomly divided into high intensity,low intensity and control groups,with 12 animals in each group.Rabbits were received a rotator cuff acute injury and reconstructing insertion of supraspinatus tendon on greater tuberosity of humerus.At 1 week after operation,rabbits were treated by continuous passive motion(CPM)apparatus,which was-60°to 60° flexion-extension for the high intensity group,and-15° to 15° for the low intensity group.At 2 weeks after operation,the CPM was performed every other day,with 10 minutes per time;which was changed to daily training from week 3 with the same frequently,and 15 minutes per time at week 4.Rabbits in the control group were housed freely.Each 4 animals were sacrificed at weeks 2,3 and 4 after operation,and the largest tensile strength and severity at osteotendinous junction were compared.RESULTS AND CONCLUSION:The maximum tensile intensity and stiffness of the supraspinatus tendon in the low intensity group were greater than that of the control and high intensity group(P＜0.05),which was smallest in the high intensity group.All the breakage point existed at the intra-articular portion.The result demonstrated that low intensity stimulation exhibits superior repair effect in acute rotator cuff injury,while high intensity stimulation is harmful to the early repair of acute rotator cuff injury.