Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.
Foot Ankle Int. 2022 Mar;43(3):404-413. doi: 10.1177/10711007211043822. Epub 2021 Sep 22.
The Evans calcaneal lengthening osteotomy procedure is widely used for correcting progressive collapsing foot deformity. However, it can result in overcorrection and degenerations of the calcaneocuboid joint. Different shapes of graft have been used in the Evans calcaneal osteotomy, but potential differences in their biomechanical effects is still unclear. The present study was designed to explore the biomechanical effects of graft shape and improve the Evans procedure to avoid or minimize detrimental effects.
Twelve patient-specific finite element models were established and validated. A triangular or rectangular wedge of varying size was inserted at the lateral edge of calcaneus, and the degree of correction was quantified. The stress in spring ligaments and plantar fascia and the contact characteristics of the talonavicular and calcaneocuboid joints were calculated and compared accordingly.
The rectangular graft provided a much higher degree of correction than triangular grafts did. However, the contact characteristics of the calcaneocuboid joint and talonavicular joint were abnormal, with clear sensitivity to increased graft size, and the modeled strain of the spring ligament increased.
The finite element analysis predicts that the rectangular grafts provide a higher degree of correction, but risks overcorrection compared with triangular grafts. The triangular graft may have a lower degree of disturbance to the biomechanical behaviors of the midtarsal joint.
The model shows that both the shape and size of an Evans osteotomy bone wedge can have effects on the contiguous joints and ligamentous structures. Those effects should be considered when selecting a bone wedge for an Evans calcaneal osteotomy.
Level III, case-control study.
Evans 跟骨延长截骨术被广泛应用于矫正进行性跟骨塌陷畸形。但该术式可能导致过度矫正和跟距、跟骰关节退变。Evans 跟骨截骨术中使用了不同形状的植骨块，但它们的生物力学效应的潜在差异尚不清楚。本研究旨在探讨植骨块形状的生物力学效应，改进 Evans 术式以避免或最小化不良影响。
建立并验证了 12 例患者特定的有限元模型。在跟骨外侧边缘插入不同大小的三角形或矩形楔形物，并量化矫正程度。计算并比较了弹簧韧带和足底筋膜的应力以及距跟、跟骰关节的接触特性。
与三角形植骨块相比，矩形植骨块提供了更高的矫正程度。然而，跟骰、距跟关节的接触特性异常，随着植骨块尺寸的增加，其敏感性明显增加，弹簧韧带的模拟应变也增加。
有限元分析预测，矩形植骨块提供了更高的矫正程度，但与三角形植骨块相比，存在过度矫正的风险。三角形植骨块可能对跗中关节生物力学行为的干扰较小。
该模型表明，Evans 截骨骨楔形块的形状和大小都会对相邻关节和韧带结构产生影响。在选择 Evans 跟骨截骨术的骨楔形块时，应考虑这些影响。
III 级，病例对照研究。
