Postural stability after a recently recovered ankle sprain, assessed with single-leg stance tests on a rigid surface and on a balance board

Background Ankle sprains are among the most common sports injuries and can impair postural stability. Single-leg stance (SLS) tests are frequently used to assess balance, but it remains unclear whether individuals recently (<1 year) injured still show deficits. This study compared postural stability between recently recovered individuals and matched healthy controls, and evaluated the effects of test difficulty and foot morphology. Given the high recurrence rate after ankle sprains, it remains important to determine whether subtle postural deficits persist despite return to sport. Methods A total of 118 physically active participants (59 recently injured (mean height 178 cm, body mass 74 kg, BMI 23.1) and 59 controls (mean height 178 cm, body mass 73 kg, BMI 22.9)) performed SLS tests under three conditions: eyes open (EO), eyes closed (EC), and balance board (BB). Center of pressure speed (CoPs) and the average length of the horizontal ground reaction force vector (HGRF) were determined. Foot type was assessed by dynamic plantar pressure scans, using the Arch Index (AI). Repeated measures ANOVA and ANCOVA (with AI as covariate) were used for within- and between-subject comparisons, respectively. Results No significant differences in CoPs or HGRF were observed between injured and non-injured legs or between groups, except for lower HGRF (indicating better stability) in the injured group during EC (p = .04). A higher Arch Index (flatter foot morphology) was associated with better stability during EO and EC, particularly in the injured group. BB testing did not reveal additional differences. Conclusion Postural stability appears restored in active individuals recently recovered from an ankle sprain. Testing on a balance board did not enhance detection of deficits. A pronated foot was linked to better postural stability, especially in the injured group. This highlights that foot morphology could be taken into account in future studies or clinical assessments.