Pollock R G, Wang V M, Bucchieri J S, Cohen N P, Huang C Y, Pawluk R J, Flatow E L, Bigliani L U, Mow V C
Orthopaedic Research Laboratory, New York Orthopaedic Hospital, NY, USA.
J Shoulder Elbow Surg. 2000 Sep-Oct;9(5):427-35. doi: 10.1067/mse.2000.108388.
The mechanical response of the inferior glenohumeral ligament to varying subfailure cyclic strains was studied in 33 fresh frozen human cadaver shoulders. The specimens were tested as bone-ligament-bone preparations representing the 3 regions of the inferior glenohumeral ligament (superior band and anterior and posterior axillary pouches) through use of uniaxial tensile cycles. After mechanical preconditioning, each specimen was subjected to 7 test segments, consisting of a baseline strain level L1 (400 cycles) alternating with either 1 (group A, 10 shoulders), 10 (group B, 13 shoulders), or 100 (group C, 10 shoulders) cycles at increasing levels (L2, L3, L4) of subfailure strain. Cycling to higher levels of subfailure strain (L2, L3, L4) produced dramatic declines in the peak load response of the inferior glenohumeral ligament for all specimens. The group of ligaments subjected to 100 cycles of higher subfailure strains demonstrated a significantly greater decrease in load response than the other 2 groups. Ligament elongation occurred with cyclic testing at subfailure strains for all 3 groups, averaging 4.6% +/- 2.0% for group A, 6.5% +/- 2.6% for group B, and 7.1% +/- 3.2% for group C. Recovery of length after an additional time of nearly 1 hour was minimal. The results from this study demonstrate that repetitive loading of the inferior glenohumeral ligament induces laxity in the ligament, as manifested in the peak load response and measured elongations. The mechanical response of the ligament is affected by both the magnitude of the cyclic strain and the frequency of loading at the higher strain levels. The residual length increase was observed in all of the specimens and appeared to be largely unrecoverable. This length increase may result from accumulated microdamage within the ligament substance, caused by the repetitively applied subfailure strains. The clinical relevance of the study is that this mechanism may contribute to the development of acquired glenohumeral instability, which is commonly seen in the shoulders of young athletes who participate in repetitive overhead sports activities.
在33个新鲜冷冻的人体尸体肩部研究了下盂肱韧带对不同亚失效循环应变的力学响应。通过单轴拉伸循环，将标本作为代表下盂肱韧带3个区域（上束以及腋前和腋后隐窝）的骨-韧带-骨制剂进行测试。在力学预处理后，每个标本接受7个测试段，包括基线应变水平L1（400个循环）与1个（A组，10个肩部）、10个（B组，13个肩部）或100个（C组，10个肩部）在逐渐增加的亚失效应变水平（L2、L3、L4）下的循环交替。循环至更高水平的亚失效应变（L2、L3、L4）导致所有标本的下盂肱韧带峰值负荷响应急剧下降。接受100个更高亚失效应变循环的韧带组在负荷响应方面的下降明显大于其他两组。所有3组在亚失效应变下的循环测试均出现韧带伸长，A组平均为4.6%±2.0%，B组为6.5%±2.6%，C组为7.1%±3.2%。在近1小时的额外时间后长度恢复极小。本研究结果表明，下盂肱韧带的重复加载会导致韧带松弛，表现为峰值负荷响应和测量的伸长。韧带的力学响应受循环应变幅度和较高应变水平下的加载频率影响。在所有标本中均观察到残余长度增加，且似乎在很大程度上不可恢复。这种长度增加可能是由于重复施加的亚失效应变导致韧带实质内累积微损伤所致。该研究的临床意义在于，这种机制可能导致后天性盂肱关节不稳定的发生，这在参与重复性过头运动的年轻运动员肩部中很常见。
