Kurata Shimpei, Inoue Kazuya, Hasegawa Hideo, Shimizu Takamasa, Iida Akio, Kawamura Kenji, Omokawa Shohei, Mahakkanukrauh Pasuk, Tanaka Yasuhito
Department of Orthopaedic Surgery, Nara Medical University, Kashihara, Nara, Japan.
Department of Hand Surgery, Nara Medical University, Kashihara, Nara, Japan.
Orthop J Sports Med. 2021 Feb 10;9(2):2325967120982947. doi: 10.1177/2325967120982947. eCollection 2021 Feb.
Acromioclavicular (AC) joint dislocation is evaluated using the radiologically based Rockwood classification. The relationship between ligamentous injury and radiological assessment is still controversial.
PURPOSE/HYPOTHESIS: To investigate how the AC ligament and trapezoid ligament biomechanically contribute to the stability of the AC joint using cadaveric specimens. The hypothesis was that isolated sectioning of the AC ligament would result in increased instability in the superior direction and that displacement >50% of the AC joint would occur.
Controlled laboratory study.
Six shoulders from 6 fresh-frozen cadavers were used in this study. Both the scapula and sternum were solidly fixed on a customized wooden jig with an external fixator. We simulated distal clavicular dislocation with sequential sectioning of the AC and coracoclavicular (CC) ligaments. Sectioning stages were defined as follows: stage 0, the AC ligament, CC ligament, and AC joint capsule were left intact; stage 1, the anteroinferior bundle of the AC ligament, joint capsule, and disk were sectioned; stage 2, the superoposterior bundle of the AC ligament was sectioned; and stage 3, the trapezoid ligament was sectioned. The distal clavicle was loaded with 70 N in the superior and posterior directions, and the magnitudes of displacement were measured.
The amounts of superior displacement averaged 3.7 mm (stage 0), 3.8 mm (stage 1), 8.3 mm (stage 2), and 9.5 mm (stage 3). Superior displacement >50% of the AC joint was observed in stage 2 (4/6; 67%) and stage 3 (6/6; 100%). The magnitudes of posterior displacement were 3.7 mm (stage 0), 3.7 mm (stage 1), 5.6 mm (stage 2), and 9.8 mm (stage 3). Posterior displacement >50% of the AC joint was observed in stage 3 (1/6; 17%).
We found that the AC ligaments contribute significantly to AC joint stability, and superior displacement >50% of the AC joint can occur with AC ligament tears alone.
The AC ligament plays an important role not only in horizontal stability but also in vertical stability of the AC joint.
肩锁关节（AC）脱位采用基于放射学的Rockwood分类法进行评估。韧带损伤与放射学评估之间的关系仍存在争议。
目的/假设：使用尸体标本研究肩锁韧带和梯形韧带如何在生物力学上对肩锁关节的稳定性产生影响。假设是单独切断肩锁韧带会导致向上方向的不稳定性增加，并且肩锁关节移位会超过50%。
对照实验室研究。
本研究使用了6具新鲜冷冻尸体的6个肩部。肩胛骨和胸骨均用外固定器牢固固定在定制的木制夹具上。我们通过依次切断肩锁韧带和喙锁韧带（CC）来模拟锁骨远端脱位。切断阶段定义如下：0期，肩锁韧带、喙锁韧带和肩锁关节囊保持完整；1期，切断肩锁韧带的前下束、关节囊和盘状结构；2期，切断肩锁韧带的后上束；3期，切断梯形韧带。在向上和向后方向对锁骨远端施加70 N的负荷，并测量移位幅度。
向上移位量平均为3.7 mm（0期）、3.8 mm（1期）、8.3 mm（2期）和9.5 mm（3期）。在2期（4/6；67%）和3期（6/6；100%）观察到肩锁关节向上移位超过50%。向后移位量分别为3.7 mm（0期）、3.7 mm（1期）、5.6 mm（2期）和9.8 mm（3期）。在3期（1/6；17%）观察到肩锁关节向后移位超过50%。
我们发现肩锁韧带对肩锁关节稳定性有显著贡献，仅肩锁韧带撕裂就可能导致肩锁关节向上移位超过50%。
肩锁韧带不仅在肩锁关节的水平水平平向稳定性中起重要作用，在垂直稳定性中也起重要作用。
