Background Patients with lateral ankle sprains represent a large group in general practice (GP) and one-third report persistent complaints, which include pain, instability or re-sprains.

Objective To investigate differences in the centre of pressure (COP) during gait and single leg stance between subjects with persistent complaints (PC) and without persistent complaints (NPC).

Design Cross-sectional case-control study.

Setting Primary care.

Patients (or participants) Forty-four patients who consulted the GP, 6 to 12 months prior to inclusion, with a lateral ankle sprain were included. Patients were divided into two study groups using a 7-point Likert recovery scale. Patients with a 1–2 score (completely recovered or strongly improved) were defined as NPC patients and with a 3–7 score (slightly improved to worse than ever) were defined as PC patients.

Assessment of risk factors An online questionnaire administered evaluating: recovery (7-point Likert scale), pain (0–10 VAS-score) and function (Ankle Function Score).

Main outcome measurements COP displacement during three tasks: barefoot walking, single leg stance with and without vision, as measured on an RSscan footscan. For each stride phase during gait, the mean COP displacement in mediolateral and anterioposterior direction was calculated. During single leg stance, mean range of the COP in mediolateral and anterioposterior were calculated as a percentage of foot length and width.

Results The COP trajectory was significantly different between NPC and PC patients in both mediolateral (p = 0.028) and anterioposterior displacement (p = 0.049) during the last stance phase of gait. No significant differences were observed during the single leg stance tasks.

Conclusions The COP trajectory seems to discriminate between patients with PC and NPC. This indicates that balance during gait might play a role in the recovery of patients after a lateral ankle sprain and might be targeted in treatment.