Three-week joint immobilization increases anterior-posterior laxity without alterations in mechanical properties of the anterior cruciate ligament in the rat knee
Three-week joint immobilization increases anterior-posterior laxity without alterations in mechanical properties of the anterior cruciate ligament in the rat knee
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DOI：
10.1016/j.clinbiomech.2020.104993
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发表时间：
2020-05-01
影响因子：
1.8
通讯作者：
Yamaoka, Kaoru
中科院分区：
文献类型：
--
作者：
Kaneguchi, Akinori;Ozawa, Junya;Yamaoka, Kaoru
背景：虽然膝关节固定可能会使前交叉韧带的力学参数恶化，如刚度和破坏强度，但是否会导致整个关节松弛尚不清楚。我们研究了固定对大鼠膝关节前后关节松弛度和前交叉韧带力学性能的影响，以及关节囊的组织学和基因表达谱。方法：采用外固定架固定大鼠单侧双膝。未固定的对侧膝关节作为对照。3周后，使用通用试验机检查整个关节（即骨骼、韧带和关节囊的复合体）的前后松弛度以及前交叉韧带的刚度和破坏强度。此外，对膝关节囊进行组织学分析，并检测关节后囊中胶原蛋白转换相关基因的表达水平。结果：与对侧相比，关节固定轻微但显著地增加了前后松动。出乎意料的是，前交叉韧带的刚度和破坏强度并没有因固定而改变。前交叉韧带僵硬度与前后关节松弛度无相关性。在关节后囊，固定后观察到胶原纤维束变薄，并伴有COL3A1基因表达减少。解释：这些结果表明，3周的关节固定改变了膝关节的生物力学完整性，而没有改变前交叉韧带的力学特性。关节囊的改变可能导致固定引起的前后松弛增加。
Background: Although knee immobilization may deteriorate the mechanical parameters of the anterior cruciate ligament, such as stiffness and failure strength, it is unknown whether it induces laxity in the whole joint. We examined the effects of immobilization on anterior-posterior joint laxity and mechanical properties of the anterior cruciate ligament, as well as histological and gene expression profiles of the joint capsule in rat knee joints.Methods: Unilateral rat knees were immobilized using an external fixator. Non-immobilized contralateral knees were used as controls. After 3 weeks, anterior-posterior laxity in the whole joint (i.e., a complex of bones, ligaments, and capsule) and stiffness and failure strength in the anterior cruciate ligament were examined using a universal testing machine. Moreover, the knee joint capsule was histologically analyzed, and the expression levels of genes related to collagen turnover in the posterior joint capsule were examined.Findings: Joint immobilization slightly but significantly increased anterior-posterior laxity compared with the contralateral side. Unexpectedly, the stiffness and failure strength of the anterior cruciate ligament were not altered by immobilization. There was no correlation found between anterior cruciate ligament stiffness and anterior-posterior joint laxity. In the posterior joint capsule, thinning of the collagen fiber bundles accompanied by a decrease in COL3A1 gene expression was observed after immobilization.Interpretation: These results suggest that 3 weeks of joint immobilization alters the biomechanical integrity in the knee joint without altering the mechanical properties of the anterior cruciate ligament. Changes in the joint capsule may contribute to the immobilization-induced increase in anterior-posterior laxity.