Department of Orthopaedic Surgery, Academic Medical Center, Orthopaedic Research Center Amsterdam, University of Amsterdam, PO Box 22660, 1100 DD Amsterdam, The Netherlands.
Arch Orthop Trauma Surg. 2011 Nov;131(11):1491-7. doi: 10.1007/s00402-011-1337-y. Epub 2011 Jun 14.
Malalignment of the hindfoot can be corrected with a calcaneal osteotomy (CO). A well-selected osteotomy angle in the sagittal plane will reduce the shear force in the osteotomy plane while walking. The purpose was to determine the presence of a relationship between the foot geometry and loading of the calcaneus, which influences the choice of the preferred CO angle.
A static free body force analysis was made of the posterior calcaneal fragment in the second half of the stance phase to determine the main loads: the plantar apeunorosis (PA) and Achilles tendon (AT). The third load is on the osteotomy surface which should be oriented such that the shear component of the force is zero. The force direction of the PA and AT was measured on 58 MRIs of the foot, and the force ratio between both structures was taken from the literature. In addition the PA-to-AT force ratio was estimated for different foot geometries to identify the relationship.
Based on the wish to minimize the shear force during walking, a mean CO angle was determined to be 33° (SD8) relative to the foot sole. In pes planus foot geometry, the angle should be higher than the mean. In pes cavus foot geometry, the angle should be smaller.
Foot geometry, in particular the relative foot heights is a determinant for the individual angle in performing the sliding calcaneal osteotomy. It is recommended to take into account the foot geometry (arch) when deciding on the CO angle for hindfoot correction.
跟骨截骨术（CO）可矫正后足对线不良。矢状面中选择合适的截骨角度可以减少步行时截骨面的剪力。目的是确定足部几何形状与跟骨负荷之间是否存在关系，这会影响首选 CO 角度的选择。
在站立后期的后半段对跟骨后段进行静态自由体力分析，以确定主要负荷：足底跟腱（PA）和跟腱（AT）。第三个负荷作用在截骨面上，该面应定向以使力的剪切分量为零。测量了 58 例足部 MRI 的 PA 和 AT 的力方向，并从文献中获取了这两种结构之间的力比。此外，还针对不同的足部几何形状估算了 PA 与 AT 的力比，以确定它们之间的关系。
基于在行走过程中最小化剪力的愿望，确定相对于足底的平均 CO 角度为 33°（SD8）。在扁平足的足部几何形状中，角度应高于平均值。在高弓足的足部几何形状中，角度应较小。
足部几何形状，特别是相对足部高度，是进行滑动跟骨截骨术时个体角度的决定因素。建议在决定跟骨后足矫正的 CO 角度时考虑足部几何形状（足弓）。
