Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, MD, USA.
J Shoulder Elbow Surg. 2020 Jul;29(7):1440-1449. doi: 10.1016/j.jse.2019.11.017. Epub 2020 Feb 17.
A synthetic ligament (LockDown, Worcestershire, England) has become available to treat complete acromioclavicular dislocation with promising clinical results and potential benefit to avoid postoperative loss of reduction. We investigated the biomechanics of this synthetic ligament in a simulated immediate postoperative rehabilitation setting, hypothesizing that the synthetic ligament would demonstrate less superior coracoclavicular displacement to cyclic loading and higher ultimate load-to-failure values than a coracoclavicular suspensory construct.
Seven matched-pair cadaveric shoulders (mean age at time of death, 79 years) were loaded cyclically and to failure. One specimen in each pair was randomly assigned to the synthetic ligament or coracoclavicular suspensory construct. Superiorly directed 70-N cyclic loading for 3000 cycles at 1.0 Hz was applied through the clavicle in a fixed scapula simulating physiologic states during immediate postoperative rehabilitation, followed by a load-to-failure test at 120 mm/min.
After 3000 cycles, the superior displacement of the clavicle in the synthetic ligament (9.2 ± 1.1 mm) was 225% greater than in the coracoclavicular suspensory construct (2.8 ± 0.4 mm, 95% confidence interval [CI] 3.4, 8.3; P < .001). Average stiffness of the synthetic ligament (32.8 N/mm) was 60% lower than that of the coracoclavicular suspensory construct (81.9 N/mm, 95% CI 43.3, 54.9; P < .001). Ultimate load-to-failure of the synthetic ligament was 23% (95% CI 37.9, 301.5; P = .016) lower than the coracoclavicular suspensory construct (580.5 ± 85.1 N and 750.2 ± 135.5 N, respectively).
In a simulated immediate postoperative cadaveric model, the synthetic ligament demonstrated poorer biomechanics than the coracoclavicular suspensory construct. These findings suggest that a coracoclavicular suspensory construct may be preferable to a synthetic ligament if early rehabilitation is intended.
一种合成韧带（英国伍斯特郡的 LockDown）已可用于治疗完全性肩锁关节脱位，其临床结果令人满意，且有可能避免术后复位丢失。我们在模拟术后即刻康复的环境中研究了这种合成韧带的生物力学特性，假设与喙锁间悬吊固定装置相比，合成韧带在循环加载下的喙锁骨间上向位移更小，失效时的极限负荷更高。
7 对匹配的尸体肩（死亡时的平均年龄，79 岁）进行循环加载和失效测试。每对中的一个标本被随机分配到合成韧带或喙锁间悬吊固定装置。通过锁骨在固定肩胛上施加 70-N 的向上指向循环力，频率为 1.0 Hz，模拟术后即刻康复期间的生理状态，进行 3000 次循环，然后以 120 mm/min 的速度进行失效测试。
3000 次循环后，合成韧带的锁骨上向位移（9.2 ± 1.1 mm）比喙锁间悬吊固定装置（2.8 ± 0.4 mm，95%置信区间 [CI] 3.4，8.3；P <.001）大 225%。合成韧带的平均刚度（32.8 N/mm）比喙锁间悬吊固定装置（81.9 N/mm，95% CI 43.3，54.9；P <.001）低 60%。合成韧带的极限失效负荷比喙锁间悬吊固定装置低 23%（95% CI 37.9，301.5；P =.016）（分别为 580.5 ± 85.1 N 和 750.2 ± 135.5 N）。
在模拟术后即刻的尸体模型中，合成韧带的生物力学性能不如喙锁间悬吊固定装置。这些发现表明，如果打算早期康复，喙锁间悬吊固定装置可能优于合成韧带。
