Centre of Rotation of the Human Subtalar Joint Using Weight-Bearing Clinical Computed Tomography

Marta Peña Fernández,Andy Goldberg,Dorela Hoxha,Gianluca Tozzi,Gordon W Blunn,Simon Mordecai,Oliver Chan

doi:10.1038/s41598-020-57912-z

Abstract

Accurate in vivo quantification of subtalar joint kinematics can provide important information for the clinical evaluation of subtalar joint function; the analysis of outcome of surgical procedures of the hindfoot; and the design of a replacement subtalar joint prosthesis. The objective of the current study was to explore the potential of full weight-bearing clinical computed tomography (CT) to evaluate the helical axis and centre of rotation of the subtalar joint during inversion and eversion motion. A subject specific methodology was proposed for the definition of the subtalar joint motion combining three-dimensional (3D) weight-bearing imaging at different joint positions with digital volume correlation (DVC). The computed subtalar joint helical axis parameters showed consistency across all healthy subjects and in line with previous data under simulated loads. A sphere fitting approach was introduced for the computation of subtalar joint centre of rotation, which allows to demonstrate that this centre of rotation is located in the middle facet of the subtalar joint. Some translation along the helical axis was also observed, reflecting the elasticity of the soft-tissue restraints. This study showed a novel technique for non-invasive quantitative analysis of bone-to-bone motion under full weight-bearing of the hindfoot. Identifying different joint kinematics in patients with ligamentous laxity and instability, or in the presence of stiffness and arthritis, could help clinicians to define optimal patient-specific treatments.

Highlights

The subtalar joint describes an articulation between talus and calcaneus, forming one of two joints of the hindfoot with the tibiotalar or ankle joint above the talus and the subtalar joint below
Following failure of non-operative management which includes the use of painkillers, ankle supports, and activity modification, the gold standard treatment for end stage subtalar joint arthritis at present consists in the removal of the subtalar joint and fusion of the talus to the calcaneus using metalwork
The ability to accurately determine the centre of rotation of human joints is important in the field of orthopaedics, where treatments involve the replacement of joints that need to replicate the native kinematics

Summary

Introduction

The subtalar joint describes an articulation between talus and calcaneus, forming one of two joints of the hindfoot with the tibiotalar or ankle joint above the talus and the subtalar joint below. Following failure of non-operative management which includes the use of painkillers, ankle supports, and activity modification, the gold standard treatment for end stage subtalar joint arthritis at present consists in the removal of the subtalar joint and fusion of the talus to the calcaneus (subtalar joint fusion) using metalwork. In this situation the talocalcaneal and or talonavicular motion is obliterated and the hindfoot moves as one structure. All previous literature reports images acquired with subjects placed in the CT scanner table in a supine position and, custom-built ankle loading devices are commonly used, images acquired are not in a weight-bearing configuration

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