Author(s): DEISTER, F., HARPUT, S.1, POTTHOAST, W.2, KARAMANIDIS, K.3, JAMES, D.1, Institution: LONDON SOUTH BANK UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 2255

INTRODUCTION:
The anterior talofibular ligament (ATFL) is typically injured in lateral ankle sprain (LAS) due to over-elongation during excessive supination. We developed a stress-imaging arthrometry (SIA) method to measure ATFL strain in vivo (1) that has potential to be a diagnostic for LAS prevention. Therefore, the purpose of this study is to examine the association between LAS and ATFL strain.
METHODS:
Bilateral ATFLs were imaged in 103 adults varying in ethnicity and physical activity (57F/46M; 18–86yrs; BMI 25.5±4.3kg/m²), including 39 with a history of LAS. SIA was performed using a custom arthrometer (2) to passively invert the ankle from 0° to 20° thereby elongating the ATFL. ATFL length and strain were measured via B-mode ultrasonography (15 MHz, 2 cm depth), accounting for the ligament’s curved path, with strain referenced to 0° inversion. Associations between ATFL strain and established LAS risk factors (previous LAS, age, BMI) as well as potential covariates (IPAQ, FAOS, CAIT, sex, ethnicity, limb dominance) were assessed using Spearman correlations for numerical variables and Mann–Whitney U tests for categorical variables. An eight step hierarchical multiple regression model was then used to assess how participant demographics collectively related to ATFL strain.
RESULTS:
ATFL elongated with ankle inversion (20.4±3.0mm to 22.4±3.4mm; P<0.001) producing 9.7±6.7% strain at 20° inversion. ATFL with a history of LAS showed nearly double the strain of an unaffected ligament (15.2±8.0% vs 7.9±5.0%; P<0.001), and dominant limbs showed higher strain than non-dominant limbs (11.0±7.0% vs 8.5±6.1%; P<0.01). FAOS (ρ=-.175; P<0.05) and CAIT (ρ=-.243; P<0.001) scores had weak but significant negative relationships with ATFL strain. The multiple regression analysis showed that previous LAS accounted for ~23% of the variance in ATFL strain (R²=0.23; P<0.001), with ATFL length at 0° contributing an additional ~6% (P<0.001) and limb dominance ~2% (P<0.05). The final model explained ~38% of the overall variability (P<0.001). Higher ATFL strain was predicted by previous LAS (B=7.8; P<0.001), older age (B=0.1; P<0.05), Black ethnicity (B=3.6; P<0.05), and IPAQ score (B=3.1×10⁻⁴; P<0.05), whereas a shorter ATFL at 0° (B=–0.7; P<0.001) and a non-dominant limb (B=–1.9; P<0.05) predicted lower strain.
CONCLUSION:
A previous LAS predicts ATFL strain to a significantly greater extent than other known risk factors associated with this injury. Although specific material properties would likely contribute to its overall explanatory strength, the regression model provides novel evidence linking participant demographics and LAS-related risk factors to ATFL biomechanical properties. These findings provide clinically relevant insight into determinants of in vivo ATFL strain and highlight the virtue of SIA as a preventative diagnostic by assessing the mechanical demand placed on the ATFL.
REFERENCES:
1) Deister et al., SSRN, 2026
2) Best et al., Knee Surgery, Sports Traumatology, Arthroscopy, 2016