Michelson James D, Hamel Andrew J, Buczek Frank L, Sharkey Neil A
Center for Locomotion Studies, The Pennsylvania State University, 29 Recreation Building, University Park, PA 16802, USA.
J Bone Joint Surg Am. 2002 Nov;84(11):2029-38. doi: 10.2106/00004623-200211000-00019.
Previous studies involving axially loaded ankle cadaver specimens undergoing a passive range of motion after fracture have demonstrated rotatory instability patterns consisting of excessive external rotation during plantar flexion. The present study was designed to expand these studies by using a model in which ankle motion is controlled by physiologically accurate motor forces generated through phasic force-couples attached to the muscle-tendon units.
Eight right unembalmed cadaver feet were tested in a dynamic gait simulator that reproduces the sagittal kinematics of the tibia while applying physiological muscle forces to the tendons of the major extrinsic muscles of the foot. Six-degrees-of-freedom kinematics of the tibia and talus were measured with use of a VICON motion-analysis system. The experimental conditions included all combinations of lateral and medial injury to reproduce the clinical classifications of ankle fracture. Statistical analysis was performed with repeated-measures analyses of variance.
The talus of the intact ankles demonstrated coupled external rotation and inversion relative to the tibia as the ankle plantar flexed. Osteotomy of the fibula, simulating a lateral ankle fracture, slightly but significantly increased external rotation and inversion of the talus (p < 0.001), whereas disruption of either the superficial or the deep deltoid ligament increased talar eversion (p < 0.003) and disruption of the deep deltoid ligament increased internal rotation (p < 0.0001). The aberrant motions were corrected by repair of the injured structure.
The predominant coupled rotation of the talus is external rotation associated with plantar flexion. Following progressive ankle destabilization, talar external rotation and inversion increased.
The clinical decision-making process regarding the treatment of ankle fractures centers on determination of whether the injury is expected to result in abnormal motion, which is thought to predispose to the development of arthritis. The present study demonstrated a remarkable degree of ankle stability during stance phase even when there was severe disruption of medial and lateral structures. This finding suggests that a main determinant of clinical outcome after ankle fracture may be ankle motion during swing phase, when ankle stability is not augmented by the combination of axial loading and active motor control of motion. If swing-phase motion is abnormal, then the ankle may be in a vulnerable position at the point of heel-strike.
先前涉及轴向加载的踝关节尸体标本在骨折后进行被动活动范围测试的研究已表明，存在旋转不稳定模式，即跖屈时出现过度外旋。本研究旨在通过使用一种模型来扩展这些研究，在该模型中，踝关节运动由附着于肌腱单位的阶段性力偶产生的生理精确肌力控制。
在动态步态模拟器中对8只未防腐处理的右踝关节尸体足进行测试，该模拟器在向足部主要外在肌肌腱施加生理肌力的同时再现胫骨的矢状面运动学。使用VICON运动分析系统测量胫骨和距骨的六自由度运动学。实验条件包括外侧和内侧损伤的所有组合，以再现踝关节骨折的临床分类。采用重复测量方差分析进行统计分析。
完整踝关节的距骨在踝关节跖屈时相对于胫骨表现出联合外旋和内翻。模拟外侧踝关节骨折的腓骨截骨术轻微但显著增加了距骨的外旋和内翻（p < 0.001），而浅三角韧带或深三角韧带的断裂增加了距骨外翻（p < 0.003），深三角韧带的断裂增加了内旋（p < 0.0001）。通过修复受损结构可纠正异常运动。
距骨的主要联合旋转是与跖屈相关的外旋。随着踝关节逐渐失稳，距骨外旋和内翻增加。
关于踝关节骨折治疗的临床决策过程集中于确定损伤是否预计会导致异常运动，而异常运动被认为易引发关节炎。本研究表明，即使在内侧和外侧结构严重破坏的情况下，站立期踝关节仍具有显著程度的稳定性。这一发现表明，踝关节骨折后临床结果的一个主要决定因素可能是摆动期的踝关节运动，此时轴向负荷和主动运动控制的联合作用并未增强踝关节稳定性。如果摆动期运动异常，那么在足跟触地时踝关节可能处于易受损位置。
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