Department of Veterans Affairs Rehabilitation Research and Development Service Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, MS 151, 1660 South Columbian Way, Seattle, WA 98108, USA.
J Bone Joint Surg Am. 2010 Jul 21;92(8):1754-64. doi: 10.2106/JBJS.I.00984.
Arthrodesis of the first metatarsophalangeal joint is indicated for severe osteoarthritis or as a revision of failed treatment for hallux valgus. The literature suggests that an optimum fused dorsiflexion angle is between 20 degrees and 25 degrees from the axis of the first metatarsal. The purpose of this study was to investigate the relationship between dorsiflexion angle and plantar pressure in the postoperative gait. We assumed that there is a fused dorsiflexion angle at which pressures are minimized under the hallux and the first metatarsal head.
Six cadaver foot specimens underwent incremental changes in simulated fused metatarsophalangeal joint dorsiflexion angle followed by dynamic gait simulation. A robotic gait simulator performed at 50% of body weight and one-fifteenth of physiologic velocity. In vitro tibial kinematics and tendon forces were based on normative in vivo gait and electromyographic data and were manually tuned to match the in vitro ground reaction force and tendon force behavior. Regression lines were calculated for peak pressure and pressure-time integral under the hallux and the metatarsal head by dorsiflexion angle.
Peak pressure and pressure-time integral under the hallux were negatively correlated with dorsiflexion angle (p < 0.004), while peak pressure and pressure-time integral under the metatarsal head were positively correlated with dorsiflexion angle (p < 0.004). The intersection of the regression lines that represented the angle at which peak pressure and pressure-time integral were minimized was 24.7 degrees for peak pressure and 21.3 degrees for pressure-time integral.
Our findings support the hypothesis that an angle-pressure relationship exists following arthrodesis of the first metatarsophalangeal joint and that it is inversely related for the hallux and the metatarsal head. Our results encompass the suggested range of 20 degrees to 25 degrees.
第一跖趾关节融合术适用于严重的骨关节炎或作为拇外翻治疗失败的翻修。文献表明，最佳融合背屈角度在第一跖骨轴线的 20 度到 25 度之间。本研究旨在探讨术后步态中背屈角度与足底压力之间的关系。我们假设存在一个融合背屈角度，在这个角度下，拇趾和第一跖骨头下的压力最小。
六个尸体足标本进行了模拟融合跖趾关节背屈角度的增量变化，然后进行动态步态模拟。机器人步态模拟器以 50%体重和 1/15 生理速度运行。体外胫骨运动学和肌腱力基于正常的体内步态和肌电图数据，并通过手动调整以匹配体外地面反作用力和肌腱力行为。通过背屈角度计算了拇趾和跖骨头下的峰值压力和压力时间积分的回归线。
拇趾下的峰值压力和压力时间积分与背屈角度呈负相关（p < 0.004），而跖骨头下的峰值压力和压力时间积分与背屈角度呈正相关（p < 0.004）。代表峰值压力和压力时间积分最小的回归线的交点为 24.7 度，用于峰值压力，21.3 度用于压力时间积分。
我们的发现支持以下假设：第一跖趾关节融合术后存在角度-压力关系，并且拇趾和跖骨头之间呈反比关系。我们的结果涵盖了建议的 20 度到 25 度的范围。
