Thordarson D B, Motamed S, Hedman T, Ebramzadeh E, Bakshian S
Department of Orthopaedic Surgery, University of Southern California, Los Angeles 90033, USA.
J Bone Joint Surg Am. 1997 Dec;79(12):1809-15. doi: 10.2106/00004623-199712000-00006.
Nine fresh-frozen cadaveric specimens were disarticulated through the knee, and the soft tissues, except for the interosseous ligaments and interosseous membrane, were removed to the level of the ankle. The subtalar joint was secured with screws in neutral position (approximately 5 degrees of valgus). Contact pressures in the tibiotalar joint were measured with use of low-grade pressure-sensitive film, which was placed through an anterior capsulotomy. For each measurement, 700 newtons of load was applied to the specimen for one minute. The film imprints were scanned, and the contact pressures were quantitated in nine equal quadrants over the talar dome. A fracture-displacement device was secured to the distal end of the fibula; the device allowed for individual or combined displacements consisting of shortening, lateral shift, and external rotation of the fibula. The ankle was maintained in neutral flexion. The ligamentous injury associated with a pronation-lateral rotation fracture of the ankle was simulated by dividing the deep fibers of the deltoid ligament, the anterior-inferior tibiofibular ligament, and the interosseous membrane to a point that was an average of fifty-three millimeters proximal to the ankle joint. Baseline contact area and contact pressure in the joint were determined, followed by measurements after two, four, and six millimeters of shortening of the fibula; after two, four, and six millimeters of lateral shift of the fibula; and after 5, 10, and 15 degrees of external rotation of the fibula. The three types of displacement were tested individually as well as in combination. The simulated deformities were found to cause a shift of the contact pressure to the mid-lateral and posterolateral quadrants of the talar dome, with pressures as high as 4.1 megapascals. A corresponding decrease in the contact pressures was noted in the medial quadrants of the talar dome. The highest pressures were recorded for maximum shortening of the fibula, the combination of maximum shortening and lateral shift, the combination of maximum shortening and external rotation, and the combination of maximum shortening, lateral shift, and external rotation. In general, increases in each displacement variable corresponded to increasing contact pressures.
九具新鲜冷冻尸体标本经膝关节离断，除骨间韧带和骨间膜外，将软组织切除至踝关节水平。距下关节用螺钉固定于中立位（约5度外翻）。通过前侧关节囊切开术，使用低等级压敏膜测量胫距关节的接触压力。每次测量时，对标本施加700牛顿的负荷，持续一分钟。扫描膜印记，并在距骨穹顶的九个相等象限中对接触压力进行定量分析。在腓骨远端固定一个骨折移位装置；该装置允许腓骨进行单独或联合移位，包括缩短、侧向移位和外旋。踝关节保持中立位屈曲。通过将三角韧带的深层纤维、胫腓前下韧带和骨间膜切断至距踝关节平均五十三毫米的近端，模拟踝关节旋前-外侧旋转骨折相关的韧带损伤。确定关节的基线接触面积和接触压力，然后在腓骨缩短2、4和6毫米后；腓骨侧向移位2、4和6毫米后；以及腓骨外旋5、10和15度后进行测量。三种类型的移位分别以及联合进行测试。发现模拟畸形会导致接触压力向距骨穹顶的中外侧和后外侧象限转移，压力高达4.1兆帕斯卡。距骨穹顶内侧象限的接触压力相应降低。腓骨最大缩短、最大缩短与侧向移位的组合、最大缩短与外旋的组合以及最大缩短、侧向移位与外旋的组合记录到的压力最高。一般来说，每个移位变量的增加都对应着接触压力的增加。
