Cao Yi, Tang Jin Bo
Department of Hand Surgery, Hand Surgery Research Center, Affiliated Hospital of Nantong University, Nantong, and Jiangsu Hand Surgery Center, Jiangsu, China.
J Hand Surg Am. 2009 Dec;34(10):1763-70. doi: 10.1016/j.jhsa.2009.08.012.
Pulleys have an important role in digital flexion, but little is known about how the strength of a tendon repair is affected by a major pulley. We evaluated the difference in strengths of flexor tendon repairs in the pulley area when the pulley was intact or divided in a chicken tendon injury model.
In each of 100 long toes of 50 Leghorn chickens, a complete, transverse laceration of the flexor digitorum profundus tendon was made in the region of the A2 pulley and was repaired surgically. The A2 pulley was preserved or was completely divided longitudinally. The toes were harvested by disarticulating through the knee joint, and placed at full extension, at 20 degrees , 40 degrees , or 60 degrees of distal interphalangeal (DIP) joint flexion, and at 40 degrees , 80 degrees , or 120 degrees of combined DIP and proximal interphangeal (PIP) joint flexion, and tendon repairs were loaded to failure in a materials testing machine. The force required for ultimate failure was statistically compared for each group.
Ultimate tendon repair strength was significantly lower in toes with the A2 pulley intact than in those with the pulley vented when the toes were placed at full extension and at all tested degrees of DIP and PIP joint flexion, except at the most marked flexion. After A2 pulley division, tendon repair strength was 30% to 60% higher than flexed toes with the pulley intact. With an intact pulley, the tendon repair strength in the flexed toes was significantly lower than that in the fully extended toes, but after A2 pulley division, the strength was similar at all toe positions except at the most marked flexion.
Chicken tendon repairs are substantially weaker when the A2 pulley is intact than when the pulley is completely divided. Loading of the tendon repair against an intact major pulley adversely affects repair strength. These findings suggest that tendon repair is less likely to fail when the A2 pulley is divided than when the pulley is intact; pulley venting may decrease the likelihood of repair ruptures.
滑车在手指屈曲中起重要作用，但关于主要滑车如何影响肌腱修复强度知之甚少。我们在鸡肌腱损伤模型中评估了滑车完整或切断时，滑车区域屈肌腱修复强度的差异。
在50只来亨鸡的100个长趾中，于A2滑车区域对指深屈肌腱进行完全横断撕裂，并进行手术修复。A2滑车予以保留或纵向完全切断。通过膝关节离断获取脚趾，将其置于完全伸展位、远侧指间（DIP）关节屈曲20度、40度或60度位，以及DIP和近侧指间（PIP）关节联合屈曲40度、80度或120度位，然后在材料试验机上对肌腱修复处加载直至断裂。对每组所需的最终断裂力进行统计学比较。
当脚趾处于完全伸展位以及所有测试的DIP和PIP关节屈曲度时，除最明显屈曲位外，A2滑车完整的脚趾中肌腱修复的最终强度显著低于滑车切断的脚趾。A2滑车切断后，肌腱修复强度比滑车完整的屈曲脚趾高30%至60%。滑车完整时，屈曲脚趾中的肌腱修复强度显著低于完全伸展的脚趾，但A2滑车切断后，除最明显屈曲位外，所有脚趾位置的强度相似。
A2滑车完整时鸡肌腱修复明显比滑车完全切断时弱。在完整的主要滑车上对肌腱修复进行加载会对修复强度产生不利影响。这些发现表明，A2滑车切断时肌腱修复失败的可能性比滑车完整时小；滑车切开可能会降低修复断裂的可能性。
