膝关节固定后髌骨腱的生物力学改变

背景：骨关节固定常作为防止受伤组织被再次损伤的方法。目的：膝关节固定对兔髌骨腱力学特性及超微形态的影响。方法：将20只成年兔等分为固定组和对照组。固定组兔左后肢通过石膏和2个可调铝夹板,保持膝伸直,踝关节屈曲90°,固定6周后,取髌骨腱-骨复合物,观察两组髌骨腱的生物力学性能和超微结构变化。结果与结论：膝关节固定6周拉伸强度和切线模量分别下降至对照组的64.44%和53.08%（P〈0.01）,但两组伸长率和最大负荷差异没有显著性意义。两组材料常数及应力应变关系曲线完全不同。固定组髌骨腱的横截面积明显大于对照组（P〈0.01）,小胶原纤维占有优势。说明固定不仅会导致髌骨腱生物力学的变化,而且对髌骨腱自身也产生影响。

Biomechanical changes in patellar tendon following knee immobilization

BACKGROUND：Bone joint immobilization is often used to prevent the injured tissue from secondary injury.OBJECTIVE：To investigate the effects of knee immobilization on biomechanical changes in rabbit patellar tendon and ultrastructure morphology.METHODS：Twenty adult rabbits were assigned into two groups.The left hindlimbs of rabbits in the immobilized group（n = 10） were immobilized by plaster of paris and two adjustable aluminium splints for 6 weeks,while those left hindlimbs in the control group（n = 10） served as controls.Rabbit knees were immobilized in extension and the ankle was immobilized at 90°flexion for 6 weeks.Then the patellar tendon-bone complex was harvested to observe the biomechanical properties and ultrastructure changes of patellar tendon.RESULTS AND CONCLUSION：After 6-week immobilization,the tensile strength and tangent modulus of patellar tendon-bone complex were decreased to 64.44% and 53.08% of the control values（P〈0.01） .However,there was no significant difference in the elongation at failure and the maximum load between the immobilized and control groups.The curves of stress and strain of patellar tendon based on the average material constant were greatly different.The cross-sectional area of patellar tendon was significantly larger in the immobilized group than in the control group（P〈0.01） .Smaller collagen fibrils took the predominance in the immobilized group.These results showed that immobilization of knee joint could result in biomechanical changes of patellar tendon and produce influence on patellar tendon.