Relationship between ankle-hind foot function and calcaneal three-dimensional morphological parameters

Xu Can; Li Ming-qing; Li Kang-hua; Liu Hua

doi:10.3969/j.issn.2095-4344.2016.46.008

Abstract：BACKGROUND:Both the overal appearance of the calcaneus and anatomical reduction of posterior subtalar joint are important prognostic factors of calcaneal intra-articular fracture repair. However, there is a lack of biomechanical data supporting the clinical importance of calcaneus height, length and heel width for the ankle-hind foot function. OBJECTIVE:To determine the correlation of the three-dimensional morphological parameters with the ankle-hind foot biomechanics as determined by the entity experiment and numerical analysis. METHODS:Models of abnormal calcaneus height, length and width were constructed in the human cadaveric feet and underwent a biomechanical load. The kinematics of the ankle-hind foot were compared between normal and simulated calcaneal fractures with reductions in calcaneal height and length as wel as increases in calcaneal width. In finite element analysis, static loading was simulated at an axial load with the subtalar joint in a neutral position, and the effects of the injured calcaneus on the contact characteristics of the subtalar joints were evaluated in terms of contact areas, peak contact pressures and pressure distributions. RESULTS AND CONCLUSION:The increase in calcaneal width somewhat limited the subtalar motion, and the reduction in length mainly limited the external rotation and plantar flexion of the subtalar joint. However, the reduction in height mainly resulted in the subtalar rotatory instability. The increase in width broadened the contact area but more notably increased the high pressure contact zone. With height loss, the overal contact area decreased, and the contact pressure center shifted to the anteroinferior portion of articulation. In conclusion, the normal biomechanics of the ankle-hind foot are severely disrupted by the abnormal calcaneus morphology. Therefore, the three-dimensional calcaneus morphology must be careful y restored in the treatment of calcaneus fractures.