Lateral Talar Subluxation Measurements in Non-Operatively Managed Weber B Ankle Fractures

Abstract

Category: Ankle; Trauma Introduction/Purpose: Isolated Weber B ankle fractures are common orthopedic injuries; however, indications for surgical management can be controversial. Stress radiographs have been utilized to evaluate the competence of the deltoid ligament, and recently lateral talar subluxation (LTS) has been described as a measurement tool for evaluating these injuries. It has been suggested that LTS >4mm on gravity stress radiographs may be utilized to determine need for surgical intervention. In this study we review the LTS measurements in a cohort of non-operatively treated isolated Weber B fibula fractures to determine its utility as a tool to potentially guide treatment decisions and its association with patient outcomes. Methods: Our group previously presented a novel algorithm for non-operative management of isolated Weber B ankle fractures and enrolled a cohort of patients. Outcome scores were reported including American Orthopaedic Foot & Ankle Society (AOFAS) hindfoot, Olerud-Molander (OMA), Foot and Ankle Ability Measure for Activities of Daily Living (FAAM/ADL), and Visual Analog Scale (VAS) scores. All patients achieved union of their fracture. For each patient we measured LTS on the injury gravity stress view x-rays as well as the un-injured contralateral side which has not been previously reported. A Kruskal-Wallis non-parametric test was used to determine whether there was any association of outcomes with extent of LTS. Results: 42 patients were included, with minimum 1 year follow-up. The average age was 49 years (range 19 to 72). On injury gravity stress radiographs, mean medial clear space (MCS) was 4.45 mm (SD = 0.93), superior clear space (SCS) 3.46 mm (SD = 0.70), and LTS 2.33 mm (SD = 1.57, range 0 – 4.7 mm), with 35 (83.3%) patients having LTS ≤ 4 mm. Contralateral (un-injured) gravity stress mean MCS was 3.39 mm (SD = 0.63), SCS 3.15 mm (SD = 0.50), and LTS 1.30 mm (SD = 1.28, range 0 - 4.8). There was no significant difference in outcome measures based on amount of LTS ( < 2 mm, 2 to 4 mm, >4 mm): AOFAS (p=0.41), OMA (p=0.40), FAAM/ADL (p=0.41), pain VAS (p=0.16). Conclusion: All patients in our cohort were successfully treated non-operatively. Most patients had injury LTS ≤ 4 mm, although those with LTS >4 mm had excellent outcome scores as well. Amount of LTS did not correlate with outcomes. We present a large range of LTS measurements in normal ankles, which may be attributed to the high variability of these measurements and sensitivity to ankle rotation on radiographs. LTS may be a useful adjunct in evaluating isolated Weber B ankle fractures but may not be entirely reliable on its own. Further studies are required to validate LTS as a quantitative decision-making tool.