Assessing mechanical ankle instability via functional 3D stress-MRI – A pilot study. (December 2019)

• Record Type: Journal Article
• Authors: Wenning, M.; Lange, T.; Paul, J.; Gollhofer, A.; Gehring, D.
• Is Part Of: Clinical biomechanics. Volume 70(2019)
• Page Start: 107
• Page End: 114
• Publication Date: 2019-12
• Subjects: Mechanical ankle instability -- 3D stress-MRI -- Cartilage contact area; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2019.07.033
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: Quantitative measurement of the mechanical deficit in chronic ankle instability (CAI) is difficult. Therefore, the distinction between functional (FAI) and mechanical ankle instability (MAI) as well as the evaluation of surgical techniques is difficult. This pilot study uses a novel method of functional 3-dimensional stress ankle-MRI to test its applicability for assessing mechanical ankle instability. Methods: We used a custom-built ankle arthrometer that allows a stepless positioning of the foot and an axial in situ loading with up to 500 N combined with a 3-dimensional MRI protocol. We assessed four parameters (3D cartilage contact area (CCA) fibulotalar, tibiotalar horizontal and vertical and intermalleolar distance) under six different conditions (neutral-null, plantarflexion-supination and dorsiflexion-pronation each with and without loading) in n = 10 individuals (7 suffering from MAI and 3 healthy controls). Findings: The MAI group showed a substantially increased reduction of lateral osseous constraint compared to healthy controls when the foot was positioned in plantarflexion-supination (CCA fibulotalar 69% vs. 30% in controls). The reduction of the weight bearing surface in plantarflexion-supination was also more pronounced (CCA tibiotalar horizontal −49% in MAI vs. −28% in controls). Interpretation: This novel technique is valuable for assessing mechanical ankle instability in the target population and has a potential clinical benefit for assessing the mechanical deficit of individual patients. Further studies are needed to provide evidence for a possible prognostic value of this novel technique. Highlights: Mechanical ankle instability may be pronounced in a plantarflexed, supination position. Functional 3D stress-MRI may allow for a quantitative analysis of ankle stability. Significant reduction of lateral 3D cartilage contact area indicates instability. Functional reduction of weight-bearing surface may explain osteochondral lesions.