Kalamazoo Center for Medical Studies, Kalamazoo, MI, USA.
Foot Ankle Int. 2013 Feb;34(2):244-50. doi: 10.1177/1071100712464214. Epub 2013 Jan 10.
The position, axis, and control of each lower extremity joint intimately affect adjacent joint function as well as whole-limb performance. A review of the literature finds little describing the biomechanics of subtalar arthrodesis and the effect on ankle biomechanics. The purpose of the current study was to establish this effect on sagittal plane ankle biomechanics.
A study was performed using a 3-dimensional, validated, computational model of the lower extremity. A subtalar arthrodesis was simulated from 20 degrees of varus to 20 degrees of valgus. At each arthrodesis position, the ankle dorsiflexor and plantarflexor muscles' fiber force, moment arm, and moments were calculated throughout a physiologic range of motion.
Throughout ankle range of motion, plantarflexion and dorsiflexion strength varied with subtalar arthrodesis position. When the ankle joint was in neutral sagittal alignment, plantarflexion strength was maximized in 10 degrees of subtalar valgus, and strength varied by a maximum of 2.6% from the peak 221 Nm. In a similar manner, with the ankle joint in neutral position, dorsiflexion strength was maximized with a subtalar joint arthrodesis in 5 degrees of valgus, and strength varied by a maximum of 7.5% from the peak 46.8 Nm. The change in strength was due to affected muscle fiber force generating capacities and muscle moment arms.
The significance of this study is that subtalar arthrodesis in a position of 5 to 10 degrees of subtalar valgus has a biomechanical advantage.
This supports previous clinical outcome studies and offers a biomechanical rationale for their generally favorable outcomes.
每个下肢关节的位置、轴和控制都密切影响邻近关节的功能以及整个肢体的性能。文献回顾发现，很少有描述距下关节融合术的生物力学以及对踝关节生物力学的影响。本研究的目的是建立距下关节融合术对矢状面踝关节生物力学的影响。
本研究使用了一个经过验证的三维下肢计算模型。模拟距下关节从 20 度内翻到 20 度外翻的融合。在每个融合位置，计算了整个生理运动范围内踝关节背屈和跖屈肌的纤维力、力臂和力矩。
在整个踝关节运动范围内，跖屈和背屈强度随距下关节融合位置的变化而变化。当踝关节处于中立矢状面时，距下关节 10 度外翻时跖屈力最大，最大变化幅度为 2.6%，峰值为 221 Nm。同样，当踝关节处于中立位置时，距下关节融合在 5 度外翻时背屈力最大，最大变化幅度为 7.5%，峰值为 46.8 Nm。强度的变化是由于受影响的肌肉纤维力产生能力和肌肉力矩臂的变化。
本研究的意义在于，距下关节融合在 5 至 10 度距下外翻的位置具有生物力学优势。
这支持了先前的临床结果研究，并为其通常良好的结果提供了生物力学依据。
