Acute lateral ankle sprain alters muscle and tendon properties: Case series.

BACKGROUND: Acute lateral ankle sprain (LAS) is the most prevalent acute sports trauma. Ankle muscle atrophy and tendon volume decrease have not been analyzed concomitantly with functional impairment and pain following LAS. The objective of the present study was to investigate muscle cross-section area (CSA), tendon CSA and volume, ankle function, and pain in individuals who suffered an acute LAS. METHODS: A series of cases, cross-sectional study with 20 participants who suffered moderate (grade II) and severe (grade III) acute LAS was undertaken. CSA for muscles (Tibialis Posterior, Fibularis, and Soleus) and tendons (Tibialis Anterior, Tibialis posterior, Fibularis, and Achilles), and volume were measured by magnetic resonance imaging (MRI) less than 48 h (baseline) and 6-weeks after the acute LAS. Ankle function (Cumberland Ankle Instability Tool [CAIT] and Foot and Ankle Outcome Score [FAOS]), ankle mechanical instability (Anterior Drawer Test [ADT]), and pain were also assessed. RESULTS: All tendons and muscles showed a significant reduction in CSA and volume between baseline and 6-weeks (P < .001). A significant decrease in ankle function was observed 6 weeks after the LAS, along with a reduction in pain and mechanical instability (P = .001). Regarding sprain magnitude, the only difference observed was greater atrophy in muscle CSA in participants with grade III ankle sprain. CONCLUSION: Patients with acute LAS showed atrophy of ankle muscles and decreased tendon volume and CSA, followed by function impairments at 6-week follow-up. LEVEL OF EVIDENCE: IV, Case series study.