Gedailovich Samuel, Deegan Liam, Hayes Westley, Koehler Steven M, Aibinder William R
College of Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
Department of Orthopaedic Surgery and Rehabilitation Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
J Shoulder Elbow Surg. 2023 May;32(5):1074-1078. doi: 10.1016/j.jse.2023.01.005. Epub 2023 Jan 31.
In nonoperative management of displaced olecranon fractures, patients are able to maintain overhead extension despite a persistent nonunion. It has been hypothesized that this is feasible because of an intact lateral cubital retinaculum. The purpose of this biomechanical study was to determine the contribution of the medial and lateral cubital retinacula to overhead extension in the setting of a displaced olecranon fracture.
Eight fresh-frozen cadaveric upper-extremity specimens were used in this study. The triceps muscle was loaded through a pulley system operated by an Instron 8874 Biaxial Servohydraulic Fatigue Testing System at a rate of 10 mm/second to simulate overhead elbow extension. Each specimen was tested in 4 states: (1) native state with an intact olecranon; (2) transverse olecranon fracture; (3) transection of 1 cubital retinaculum (medial or lateral); and (4) transection of both medial and lateral cubital retinacula. The primary outcome was the ability to perform overhead extension. The secondary outcome was the force needed to generate extension.
Elbow extension was noted in each specimen for trials 1, 2, and 3. Only when both the lateral fascia and medial fascia were transected was elbow extension not achieved. There was no significant difference in the force required to generate extension in the first 3 trials (P = .99). There was no significant difference in the change in the maximum force required to achieve extension between the specimens with only the medial side transected and the specimens with only the lateral side transected (P = .07).
In the setting of an olecranon fracture, this biomechanical study suggests that if either the lateral or medial cubital retinaculum remains in continuity with the distal ulna, active overhead extension can be maintained. This finding may explain the positive clinical outcomes of nonoperative management of displaced olecranon fractures in the elderly patient population. Determining the integrity of the fascial structures preoperatively may help select candidates for nonoperative treatment of displaced olecranon fractures.
在移位性鹰嘴骨折的非手术治疗中，尽管存在持续性骨不连，患者仍能够保持过顶伸展。据推测，这是可行的，因为外侧肘支持带完整。本生物力学研究的目的是确定在移位性鹰嘴骨折情况下，内侧和外侧肘支持带对过顶伸展的作用。
本研究使用了8个新鲜冷冻的尸体上肢标本。通过由Instron 8874双轴伺服液压疲劳测试系统操作的滑轮系统以10毫米/秒的速率加载肱三头肌，以模拟肘部过顶伸展。每个标本在4种状态下进行测试：（1）鹰嘴完整的原始状态；（2）鹰嘴横行骨折；（3）切断1条肘支持带（内侧或外侧）；（4）切断内侧和外侧肘支持带。主要结果是进行过顶伸展的能力。次要结果是产生伸展所需的力。
在试验1、2和3中，每个标本均观察到肘部伸展。只有当外侧筋膜和内侧筋膜均被切断时，才无法实现肘部伸展。在前3次试验中，产生伸展所需的力没有显著差异（P = 0.99）。仅内侧切断的标本和仅外侧切断的标本之间，实现伸展所需的最大力的变化没有显著差异（P = 0.07）。
在鹰嘴骨折的情况下，本生物力学研究表明，如果外侧或内侧肘支持带与尺骨远端保持连续，则可以维持主动过顶伸展。这一发现可能解释了老年患者移位性鹰嘴骨折非手术治疗的良好临床结果。术前确定筋膜结构的完整性可能有助于选择移位性鹰嘴骨折非手术治疗的候选者。
