Isolated syndesmotic injuries in acute ankle sprains: diagnostic significance of clinical examination and MRI

PURPOSE: Acute ankle sprains are frequently accompanied by syndesmotic injuries. These injuries are often overlooked in clinical examinations. The aim of this study was (1) to evaluate the incidence of syndesmotic injuries in acute ankle sprains using MRI, (2) to determine the accuracy of common clinical diagnostic tests, (3) to analyse their inter-rater reliability, and (4) to evaluate the role of clinical symptoms in the diagnosis of syndesmotic injuries.

METHODS: A total of 100 patients with acute ankle sprain injury without associated fractures in plane radiographs were enrolled. The clinical assessment was performed by two independent examiners. Local findings, ankle ligament palpation, squeeze test, external rotation test, Drawer test, Cotton test, and the crossed-leg test (two examiners) were compared with MRI results (read by two blinded radiologists) as a reference standard.

RESULTS: Ninety-six participants (57 % male) met the inclusion criteria. MRI detected a ruptured anterior inferior tibiofibular ligament (AITFL) in 14 patients (15 %); 9 partial tears and 5 complete tears were evident. Evidence of pain at rest was found to predict syndesmotic injuries most accurately (p = 0.039). The palpation test over the proximal fibula produced the highest inter-rater correlation (κ = 0.65), but the lowest sensitivity for syndesmotic injuries of 8 %. All other clinical tests demonstrated moderate to fair inter-rater reliabilities (κ = 0.37-0.52). Low sensitivity values were found with all clinical tests (13.9-55.6 %).

CONCLUSION: In this study, clinical examination was insufficient to detect syndesmotic injuries in acute ankle sprains. MRI scanning revealed a syndesmotic lesion in 15 % of patients. MRI scanning should be recommended in patients with ongoing pain at rest following ankle sprains.

LEVEL OF EVIDENCE: I.