Debski R E, Wong E K, Woo S L, Sakane M, Fu F H, Warner J J
Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pittsburgh, Pennsylvania 15213, USA. genesis1+@pitt.edu
J Orthop Res. 1999 Sep;17(5):769-76. doi: 10.1002/jor.1100170523.
Our objective was to examine the function of the glenohumeral capsule and ligaments during application of an anterior-posterior load by directly measuring the in situ force distribution in these structures as well as the compliance of the joint. We hypothesized that interaction between different regions of the capsule due to its continuous nature results in a complex force distribution throughout the glenohumeral joint capsule. A robotic/universal force-moment sensor testing system was utilized to determine the force distribution in the glenohumeral capsule and ligaments of intact shoulder specimens and the joint kinematics resulting from the application of external loads at four abduction angles. Our results suggest that the glenohumeral capsule carries no force when the humeral head is centered in the glenoid with the humerus in anatomic rotation. However, once an anterior-posterior load is applied to the joint, the glenohumeral ligaments carry force (during anterior loading, the superior glenohumeral-coracohumeral ligaments carried 26+/-16 N at 0 degrees and the anterior band of the inferior glenohumeral ligament carried 30+/-21 N at 90 degrees). Therefore, the patient's ability to use the arm with the humerus in anatomic rotation should not be limited following repair procedures for shoulder instability because the repaired capsuloligamentous structures should not carry force during this motion. Separation of the capsule into its components revealed that forces are being transmitted between each region and that the glenohumeral ligaments do not act as traditional ligaments that carry a pure tensile force along their length. The interrelationship of the glenohumeral ligaments forms the biomechanical basis for the capsular shift procedure. The compliance of the joint under our loading conditions indicates that the passive properties of the capsule provide little resistance to motion of the humerus during 10 mm of anterior or posterior translation with anatomic humeral rotation. Finally, this knowledge also enhances the understanding of arm positioning relative to the portion of the glenohumeral capsule that limits translation during examination under anesthesia.
我们的目的是通过直接测量这些结构中的原位力分布以及关节的顺应性，来研究在施加前后负荷时盂肱关节囊和韧带的功能。我们假设，由于关节囊的连续性，其不同区域之间的相互作用会导致整个盂肱关节囊内出现复杂的力分布。利用机器人/通用力-力矩传感器测试系统，确定完整肩部标本的盂肱关节囊和韧带中的力分布，以及在四个外展角度施加外部负荷时产生的关节运动学。我们的结果表明，当肱骨头在关节盂中居中且肱骨处于解剖位旋转时，盂肱关节囊不承受力。然而，一旦对关节施加前后负荷，盂肱韧带就会承受力（在前负荷期间，盂肱上韧带-喙肱韧带在0度时承受26±16牛的力，盂肱下韧带前束在90度时承受30±21牛的力）。因此，在进行肩部不稳修复手术后，患者在肱骨处于解剖位旋转时使用手臂的能力不应受到限制，因为修复后的关节囊韧带结构在此运动过程中不应承受力。将关节囊分离成其组成部分后发现，力在每个区域之间传递，并且盂肱韧带并非像传统韧带那样沿其长度承受纯拉力。盂肱韧带的相互关系构成了关节囊移位手术的生物力学基础。在我们的负荷条件下，关节的顺应性表明，在肱骨进行10毫米的前后平移且处于解剖位旋转时，关节囊的被动特性对肱骨运动几乎没有阻力。最后，这一知识也增强了我们对在麻醉检查期间相对于限制平移的盂肱关节囊部分的手臂定位的理解。
