应力负荷对关节镜下骨铆钉治疗兔急性肩袖损伤后骨-肌腱修复过程的影响

Effect of stress load on bone-tendon repair process after the arthroscopic treatment of bone rivets for acute rotator cuff injury in rabbits

目的探讨不同强度应力刺激对关节镜下骨铆钉治疗兔急性肩袖损伤后腱．骨修复过程的影响。方法30只成年新西兰大白兔随机分为高强度组、低强度组和对照组，每组10只。建立兔肩袖损伤模型并采用关节镜下骨铆钉进行修复。术后1周开始功能锻炼，高强度组肩关节活动范围-60°～60°，低强度组肩关节活动范围-15°～15°，对照组自由活动，同期行肩关节MRJ检查。术后2、3、4周处死动物，检测冈上肌骨．肌腱交界面标本的刚度和最大抗拉强度。结果3组标本大体观察无明显差异。影像学显示低强度组肌腱信号均匀，未见明显关节腔内高信号影；而高强度组及对照组均显示肌腱内信号不均，关节腔内可见信号增高影。术后2、3、4周，低强度组刚度和最大抗拉强度均优于高强度组和对照组（P〈O．05）。结论在关节镜下骨铆钉治疗肩袖损伤的早期修复过程中，与高强度应力刺激相比，低强度应力刺激能够提高骨．肌腱交界面的力学强度，效果较好。

Objective To study the effect of stress stimulation in different intensity on bone-tendon repair process after acute rotator cuff injury in rabbits treated by bone rivets under arthroscopy. Methods According to whether performed postoperative function exercises, and the intensity of activity, 30 adult New Zealand white rabbits were randomly divided into 3 groups： high-intensity experimental group （range of motion of shoulder joint was --60~ to 60~）, low-intensity experimental group （range of motion of shoulder joint was --15~ to 15~） and control group （free activity permitted）. Models of rotator cuff injury in rabbits were established, and bone rivets were used to repair the injury under arthroscopy. Joint functional exercises were performed 1 week after the surgery, MRI examination of shoulder joint were undergone simultaneously. Animals were sacrificed at 2, 3, 4 week after the surgery by intravenous injection of air respectively, and the stiffness and ultimate tensile strength of specimens taken from supraspinatus tendon-bone interface were observed in each group. Results Gross observation showed no obvious differences among 3 groups. In low-intensity experimental group, MRI results showed homogeneous signals in muscle tendon, while no obvious high signal intensity in articular cavity; In high-intensity experimental group and control group, heterogeneous signals in muscle tendon and high signal intensity in articular cavity were found in MRI images. At 2, 3, and 4 week after the surgery, stiffness and maximum tensile strength in low-intensity group were significantly higher than those in control group and high-intensity group （P 〈0.05）. Conclusion During the early repair process for acute rotator cuff injury treated by bone rivets under arthroscopy, low-intensity stimulation can improve biomechanical strength of bone-tendon interface, and therefore can get better effects compared with high-intensity stimulation.