Foot and Ankle Service, Hospital for Special Surgery, New York, NY.
Department of Biomechanics, Hospital for Special Surgery, New York, NY.
J Bone Joint Surg Am. 2024 May 15;106(10):906-911. doi: 10.2106/JBJS.23.00866. Epub 2024 Mar 12.
Reduced hindfoot eversion motion has been proposed as a cause of increased lateral foot pressure following lateral column lengthening (LCL) for progressive collapsing foot deformity (PCFD). A subjective intraoperative assessment of passive eversion has been suggested to help evaluate correction; however, it is unclear how passive eversion correlates with objective measurements of foot stiffness. Our objectives were to quantify the relationship between the maximum passive eversion in hindfoot joints following LCL with plantar pressure during stance and to determine the influence of wedge size on these outcomes.
Ten cadaveric specimens extending from the mid-tibia distally were tested on a 6-degrees-of-freedom robot to simulate the stance phase of level walking. Five conditions were tested: intact, simulated PCFD, and 3 LCL wedge conditions (4, 6, and 8 mm). Outcomes included the lateral-to-medial forefoot plantar pressure (LM) ratio during stance and the maximum passive eversion measured in the hindfoot joints. Simple linear regressions were performed to evaluate relationships between outcomes and wedge sizes.
A strong negative relationship was found between passive subtalar eversion and the LM ratio during stance (r[38] = -0.46; p = 0.0007), but not between passive talonavicular eversion and the LM ratio (r[38] = -0.02; p = 0.37). Wedge size was strongly related to subtalar eversion (r[38] = -0.77; p < 0.0001), talonavicular eversion (r[38] = -0.55; p = 0.0003), and the LM ratio (r[38] = 0.70; p < 0.0001). Increased wedge size resulted in average decreases in subtalar and talonavicular eversion of 1.0° (95% confidence interval [CI]: 0.8° to 1.3°) and 1.2° (95% CI: 0.6° to 1.6°), respectively. Increased wedge size also increased the LM ratio by 0.38 (95% CI: 0.25 to 0.50), indicating a lateral shift in plantar pressure.
Decreased hindfoot eversion following LCL was related to increased lateral plantar pressure during stance. Increasing wedge size correlated with decreasing passive hindfoot eversion and increasing lateral plantar pressure, suggesting that intraoperative preservation of eversion motion may be important for preventing excessive lateral loading.
To avoid overcorrection or undercorrection of the deformity, hindfoot eversion assessment in addition to radiographic evaluation may be important for optimizing the amount of lengthening to achieve successful LCL.
在进行外侧柱延长术（LCL）治疗进行性塌陷足畸形（PCFD）时，已经提出减少后足外翻运动是导致外侧足压增加的原因。已经提出了对被动外翻的术中主观评估以帮助评估矫正效果；但是，目前尚不清楚被动外翻与足部僵硬的客观测量值之间如何相关。我们的目标是量化 LCL 后后足关节的最大被动外翻与站立时的足底压力之间的关系，并确定楔子大小对这些结果的影响。
十具从胫骨中部向远端延伸的尸体标本在六自由度机器人上进行测试，以模拟水平行走的站立阶段。测试了五种情况：完整，模拟 PCFD 和 3 个 LCL 楔形物（4、6 和 8 毫米）条件。结果包括站立时前足内侧至外侧的足底压力（LM）比值和后足关节的最大被动外翻。进行简单线性回归以评估结果与楔形物尺寸之间的关系。
在站立时，被动距下关节外翻与 LM 比值之间发现了很强的负相关关系（r[38] = -0.46；p = 0.0007），但是被动距舟关节外翻与 LM 比值之间没有相关性（r[38] = -0.02；p = 0.37）。楔子大小与距下关节外翻（r[38] = -0.77；p < 0.0001），距舟关节外翻（r[38] = -0.55；p = 0.0003）和 LM 比值（r[38] = 0.70；p < 0.0001）之间具有很强的相关性。楔子尺寸的增加导致距下关节和距舟关节外翻的平均减小分别为 1.0°（95％置信区间[CI]：0.8°至 1.3°）和 1.2°（95％CI：0.6°至 1.6°）。楔子尺寸的增加还使 LM 比值增加了 0.38（95％CI：0.25 至 0.50），表明足底压力向外侧发生了转移。
LCL 后后足外翻减少与站立时的外侧足底压力增加有关。楔子尺寸的增加与被动后足外翻减少和外侧足底压力增加相关，这表明术中保留外翻运动对于防止过度侧向加载可能很重要。
为了避免畸形的过度矫正或矫正不足，除了影像学评估外，后足外翻评估对于优化延长量以实现成功的 LCL 可能很重要。
