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.
ABSTRACT
BACKGROUND: Supraspinatus tendon injury is common in rotator cuff injury, the repair difficulty of which is reconstructing the bone-tendon interface. Currently, there are no effective therapeutics and suitable experimental animal models.OBJECTIVE: To establish rabbit rotator cuff injury prosthetic experimental animal model and to observe the effect of continuous passive motion (CPM) on early healing of rabbit rotator cuff bone-tendon interface by MRI, which can provide guidance for preparing an optimal rehabilitation strategy after rotator cuff injury.METHODS: Sixteen male New Zealand rabbits, aged 8 months, were received a rotator cuff acute injury and reconstructing insertion of supraspinatus tendon on greater tuberosity of humerus. The rabbits were randomly divided into cage activity group (n=4) and CPM group (n=12). At 2 days after operation, rabbits were treated by rabbit shoulder joint continuous passive motion apparatus of 75°～75° flexion-extension with various CPM speeds[2 (°)/s, 4 (°)/s, and 10 (°)/s)]. General state and MRI changes of rabbit rotator cuff bone-tendon interface was observed prior to and at weeks 1,2, and 4 after operation.RESULTS AND CONCLUSION: Gross observation showed that the incisions healed very well at 2 weeks after operation. There was no infection, haematoma or disruption after removing the suture. Compared to the cage activity group, the tendon-bone interface of CPM group heeled better at weeks 1, 2 and 4, especially at the speed of 4°/s with 75°-75° flexion-extension. Results demonstrated that this animal model can be satisfied to experimental study. From the following day after operation, various CPM speeds can accelerate the healing of tendon-bone interface, and the optimal speed of CPM was 4 (°)/s.
ABSTRACT
[Objective]To evaluate the effectiveness of recombinant human bone morphogenetic protein-2 in the repair of rabbit rotator cuff injury.[Method]Forty-eight male New Zealand rabbits,aged 8 months,received an rotator cuff acute injury and reconstruction of the insertion of supraspinatus tendon on greater tuberosity of humerus.The rabbits were randomly divided into 3 groups postoperatively:(1) rhBMP-2 group:fibrin sealant(FS) containing rhBMP-2 was applied to the interface between the bone-tendon interface; (2)FS control group:only FS was applied;(3)blank control group:untreated after the surgery.Harvested 36 specimens underwent biomechanical analysis at the 2nd,4th,8th postoperative weeks respectively.Harvested 12 specimens underwent histological analysis at the 8th postoperative week.[Result]Histological examination showed that Sharpey's fibers were found in the interface with the formation of four-layer indirect insertion in the rhBMP-2 group at the 8th postoperative week.In the FS control group and blank group,the tendon-bone interface was filled with granulation tissue and part of Sharpey's fibers and the newly generated bone tissue.Biomechanical analysis displayed that the tensile strength and stiffness of bone-tendon interface increased time-dependently in all groups,and it in the rhBMP-2 group was significantly higher than those in the other two groups at any time-points (both P