Background Persistent complaints are very common after a lateral ankle sprain however, prognostic factors are largely unknown.

Objective To examine the five-year prognosis and potential prognostic factors of patients with an acute lateral ankle sprain in general practice (GP).

Design Observational study.

Setting Primary care.

Patients 206 patients who participated in a cross-sectional study and visited their GP with a lateral ankle sprain 6 to 12 months prior to inclusion were approached for a 5-year follow-up measurement consisting of an online questionnaire.

Assessment of risk factors At baseline, all patients received a standardised questionnaire, underwent a physical examination and MRI assessment of their ankle. Potential prognostic factors included patient characteristics (age, gender, BMI), symptoms (pain: NRS/10), Ankle Function Score (AFS/100), perceived recovery (7-point Likert) and structural abnormalities on MRI (bone marrow lesions and cartilage loss).

Main outcome measurements The online follow-up questionnaire assessed perceived recovery (dichotomized in persistent complaints: ‘completely recovered or strongly improved’ and no persistent complaints: ‘slightly improved to worse than ever’), pain at rest and during exercise (NRS/10), AFS and re-sprains.

Results Of the 206 included patients, 132 (64.1%) patients completed the 5-year follow-up questionnaire. Age and pain during exercise at baseline were significantly higher in the responders. After 5-years follow-up, persistent complaints were reported by 18.2% compared to 40.9% at baseline and a re-sprain had occurred in 29.5% of the responders. The mean AFS was 79.9 (26.1). BMI, perceived recovery, AFS and pain at rest and during exercise at baseline were univariate significantly associated with persistent symptoms at 5-year follow-up. None of the variables were significantly associated with persistent complaints in the multivariable model.

Conclusions Almost 20% of patients who visited their GP with a lateral ankle sprain experience persistent complaints after 5 years follow-up. No prognostic factors could be determined for these persistent complaints.