Evaluation of the Anterior Tibialis Tendon Using Elastography in Patients With Hallux Valgus

To elucidate the relationship between changes in the mechanical properties of the tibialis anterior tendon and deformity in patients with hallux valgus, a case-control study is planned to quantitatively measure tendon stiffness using shear-wave elastography (SWE). Two groups will be compared: adults with radiographically confirmed hallux valgus (HVA (Hallux valgus angle) ≥15°) and age- and gender-matched healthy controls. The primary outcome is the elasticity modulus of the tibialis anterior tendon measured by SWE (kPa). Measurements will be performed using a high-frequency linear probe, with the probe positioned parallel to the tendon fibers and the foot in the standard ankle position, with three repetitions performed on each subject; the mean of stable frames will be used in the analysis. Secondary variables will be the relationships between tendon thickness/cross-sectional area, clinical angle parameters (HVA, IMA (intermetatarsal angle)), and functional scores. In the reliability sub-study, intra- and inter-observer ICC (Intraclass Correlation Coefficient), SEM (Standard Error of Measurement), and MDC (Minimal Detectable Change) will be calculated. The sample size was calculated for a two-sample, two-tailed t-test with α=0.05 and 80% power assumptions, targeting a clinically meaningful medium-to-high effect size (Cohen d=0.60); at least 45 patients (45 with hallux valgus + 45 healthy) were planned. Parametric/non-parametric tests appropriate for the distribution and ANCOVA for potential confounders (age, gender, BMI, foot dominance) will be used in the analyses. The study is expected to objectively demonstrate whether tibialis anterior tendon stiffness changes in hallux valgus, thereby clarifying the muscle-tendon contributions to pathomechanics and laying the groundwork for targeted strategies in both conservative and surgical treatment planning.