Forty-seven patients with acute lateral ankle sprains were randomized to receive either the Malleo TriStep phase-adapted orthosis or the Aircast Air-Stirrup nonphase-adapted orthosis. The purpose of this study was to compare the two types of orthoses over 3 months in terms of functional outcomes following acute ankle sprain. Results indicated no difference between groups in terms of ankle (FOAS and AOFAS) scores and balance tests. However, functional and agility tests demonstrated a benefit in favour of the Malleo TriStep group. Comparisons form this study involving a healthy control group where not included in this report.