TIBIOFIBULAR CLEAR SPACE WIDENING ASSOCIATED WITH ANKLE DORSIFLEXION IN PATIENTS WITH CHRONIC ANKLE INSTABILITY: AN ULTRASONOGRAPHIC STUDY

T. Tashiro¹, N. Maeda¹, S. Tsutsumi¹, T. Abekura¹, H. Esaki¹, K. Tsuchida¹, S. Oda¹, M. Komiya¹, Y. Urabe¹

¹Graduate School of Biomedical and Health Science, Hiroshima University, Department of Sport Rehabilitation, Hiroshima, Japan

Background: Tibiofibular clear space (TFCS) widening associated with repeated lateral ankle sprains can lead to anterior inferior tibiofibular ligament injury, resulting in complications of chronic ankle instability (CAI). TFCS widening affects the mortise structure and is associated with excessive talar rotation. However, no reports have examined TFCS in CAI cases.

Purpose: The purpose of this study was to identify TFCS at four ankle angles in the CAI cases using ultrasound and compare it to healthy cases.

Methods: Twenty-four young healthy adults with 48 feet (Control group) and 14 CAI cases with 25 feet (CAI group) were included in the study. The CAI group was defined by the Cumberland ankle instability tool (CAIT) as 24 points or less. Participants underwent US assessment in sitting position with the four different ankle angles: plantar flexion 20 degrees (P20), neutral position (N), dorsiflexion 20 degrees (D20), and dorsiflexion 20 degrees + external rotation 30 degrees (D20ER30). TFCS was measured as the narrowest distance between the tibia and fibula at the deepest level of the anterior inferior tibiofibular ligament. In the statistical analysis, a two-way ANOVA was performed with the measurement group and ankle angle as independent variables and TFCS as the dependent variable. As post hoc tests, an unpaired t-test was performed for the comparison of TFCS between groups and a Bonferroni test between different ankle angles.

Results: TFCS in the control group was 5.40 ± 1.48 mm for P20, 5.70 ± 1.63 mm for N, 6.11 ± 1.53 mm for D20, 6.57 ± 1.66 mm for D20ER30, and 6.33 ± 1.65 mm, 6.45 ± 1.58 mm, 6.67 ± 1.69 mm, and 7.27 ± 1.88 mm in the CAI group (main effect of group factor: p<0.001, main effect of ankle angle factor: p=0.001, interaction effect: p=0.931). TFCS in the CAI group was significantly wider at P20 than in the control group (p=0.017). In the control group, there were significant differences in TFCS with changes in ankle angle (P20 vs D20: p=0.170, P20 vs D20E30: p<0.001, N vs D20ER30: p=0.040).

Conclusions: This study is the first report of the identification of TFCS in CAI by ultrasound. A previous study reported that the distal part of the fibula is externally displaced in CAI cases with repeated lateral ankle sprains (Kobayashi T et al., 2014). As a result, TFCS may have been wider in the CAI group compared with the control group. Interestingly, in the CAI cases, even in plantar flexion, where the TFCS is supposed to narrow the most, it was wider than in the control cases. Clinicians may need to approach TFCS to address ankle instability in CAI cases.

Implications: Evaluation of TFCS by ultrasonography may be a useful technique to detect CAI in the clinical setting.

Funding acknowledgements: We have no funding acknowledgement in this study.

Keywords:
Distal tibiofibular joint
Chronic ankle instability
Ultrasound

Topics:
Musculoskeletal: lower limb
Sport & sports injuries

Did this work require ethics approval? Yes

Institution: Ethical Committee for Epidemiology of Hiroshima University

Committee: Ethical Committee for Epidemiology of Hiroshima University

Ethics number: E-4091