Abstract
ABSTRACTBone shapes, particularly those defining the subtalar joint (STJ), have not received much attention yet as a risk factor for developing chronic ankle instability (CAI) after sustaining a lateral ankle sprain (LAS). This study aimed to compare three‐dimensional (3D) shape variations in the STJ bones within individuals with CAI and healthy controls. 3D statistical shape models (SSMs) of the STJ bones were built to describe the bone shape variations observed within a population consisting of 26 individuals with unilateral CAI and 26 healthy controls. Using the SSMs and analysis of covariance test, age‐ and gender‐adjusted shape variations in the bones were compared within individuals with CAI and healthy controls. The mean age of the CAI patients (14 males and 12 females) and healthy controls (12 males and 14 females) was 29 (standard deviation [SD] = 11) and 36 years (SD = 11), respectively. Tali and calcanei did not significantly vary between ipsilateral CAI and their contralateral ankle. Two shape modes, one for the talus (p = 0.015, variations in the curvature of the talar lateral process and the inclination angle of the talar neck relative to the body) and one for the calcaneus (p = 0.003, variations in the medial and lateral tuberosities, and the contour of the anterior articular surface), described significant shape differences between the CAI patients and healthy controls. The CAI patients generally had flatter talar joint surfaces and a flattened calcaneal ground‐contact surface. These findings suggest that specific bone shapes may increase the risk of developing CAI after sustaining a LAS. © 2019 The Authors. Journal of Orthopaedic Research® Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:1892–1902, 2019
Highlights
Lateral ankle sprain (LAS) comprises approximately 80% of all ankle sprains,[1,2] leading to an average of two million cases in the United States[3] annually and an estimated 5% of emergency room visits in the United Kingdom.[4]
Cohort Characteristics The chronic ankle instability (CAI) patients were almost distributed in terms of their gender (14 males and 12 females)
The 3D statistical shape models of the talus and calcaneus were built based on the mixed data of patients with unilateral CAI and healthy controls
Summary
Lateral ankle sprain (LAS) comprises approximately 80% of all ankle sprains,[1,2] leading to an average of two million cases in the United States[3] annually and an estimated 5% of emergency room visits in the United Kingdom.[4]. Most patients experiencing a LAS can be successfully treated and regain functional ankle stability with conservative treatment.[7,8] Despite recommended conservative treatments (e.g., functional support and exercise therapy),[9] up to 40% of the patients continue to suffer from residual complaints[10,11,12,13,14] and may progress to chronic ankle instability (CAI).[15] CAI is defined as the instability of the ankle with the feeling of giving‐way, episodes of recurrent ankle sprains, with or without the presence of joint laxity.[2,16]. In up to 58% of the cases, instability does not solely appear in the talocrural joint (TCJ), but is present in the STJ of CAI patients.[2]
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