目的:通过肩关节三维模型构建和有限元分析探讨改良线袢法Latarjet术后移植骨块微动的生物力学机制.方法:采集美国虚拟人网站(Visible Hum)的男性人体(亚洲)数据库右肩数据,根据肩关节复发脱位改良线袢法Latarjet手术技术过程构建有限元模型,包含肩胛骨、肱骨、锁骨、移植骨块,模拟肱骨在肩胛骨平面外旋,模拟肱骨头与关节盂相对活动,收集相关应力数据、应力图片和位移图片(以骨块中心为基点,分别设置X-骨块沿肩胛骨左侧滑行方向、Y-骨块向肩胛骨下方滑行方向、Z-骨块向外运动方向),分析肱骨及移植骨块应力变化.结果:1)肱骨外旋并与移植骨块撞击开始后,骨块所承受的撞击应力主要集中在移植骨块与高强线连接处.但随着肱骨的外旋角度增大,应力不再集中在移植骨块与高强线连接处,而表现为上下延展向骨块四周扩布,类似肱骨沿撞击中心的扩散分布.2)随着肱骨的外旋角度增大,移植骨块在被撞击过程中于X、Y、Z方向产生位移.大致可以分为两个阶段:肱骨外旋角度为0°～10.89°时,Z方向位移几乎没有(小于0.2且增值较小),该阶段中移植喙突骨块主要向肩胛骨内、下位移,其X方向位移最大值为2.05 mm,其Y向位移最大值为0.50 mm;当肱骨外旋角度为10.89°～24°时,Z方向的位移不断增加直至2.22 mm,骨块沿X方向增加直至2.89 mm,而骨块沿Y向的位移不再增加,保持在0.40 mm左右.此时移植骨块位移以向外侧翻转为主,附带向X方向的少量滑移.总的来说,3个方向位移距离随外旋过程增大;其位置由稍外于关节盂关节面,逐渐与之持平,最后稍偏内于关节面.结论:改良线袢固定法Latarjet术后早期移植骨块在肩关节外旋过程中产生微动;且肱骨与移植骨块的接触区始终为最大应力区,总体应力沿撞击中心向四周类同心圆样扩散分布,应力大小则呈阶梯状由内到外层层递减,可能与骨块塑形有关.

Objective:To observe the changes in acromiaohumeral distance(AHD) in patients undergoing the modified arthroscopic double-button Latarjet procedure for recurrent anterior shoulder dislocation complicated with glenoid bone defect.Methods:A retrospective study was performed of the 52 patients who had undergone the modified arthroscopic double-button Latarjet procedure from October 2014 to October 2016 at Department of Sports Medicine, The First Affiliated Hospital to Shenzhen University for recurrent anterior shoulder dislocation complicated with glenoid bone defect. They were 33 males and 19 females, having 30 left and 22 right shoulders affected. Their ages ranged from 19 to 45 years(mean, 29.6 years). Their glenoid bone defects ranged from 17% to 30%(mean, 23.4%). CT scans were performed on the surgery side to observe the healing and reshaping of the bone grafts and to measure the AHDs of healthy shoulder, immediately, 6, 18 and 36 months after operation. Their American Shoulder and Elbow Surgeons(ASES), Rowe and Walch-Duplay scores were recorded before operation and at the final follow-up for comparison.Results:The follow-up time for this series ranged from 37 to 44 months (mean, 40.6 months). The AHDs at immediate postoperation(9.6 mm ± 0.7 mm), 6 months postoperation(8.6 mm ± 0.9 mm), 18 months postoperation (8.0 cm ± 0.8 cm) and 36 months postoperation(7.9 cm ± 0.8 cm) were significantly wider than the healthy side value (7.8 mm ± 0.8 mm)( P<0.05). The ASES, Rowe and Walch-Duplay scores at the final follow-up (93.9±3.2, 94.5±2.7 and 95.7±3.6) were significantly improved than the preoperative values (67.3±9.1, 40.1±4.2 and 63.5±9.0) ( P<0.05). The final follow-ups observed no symptoms or signs of chronic shoulder pain, rotator cuff injury or acromion impingement. Conclusion:As the AHD becomes wider rather than narrower after arthroscopic double-button Latarjet procedure for recurrent anterior shoulder dislocation complicated with glenoid bone defect, no subsequent rotator cuff injury may happen due to the uplift of the humeral head after the modified arthroscopic double-button Latarjet procedure.