Diagnostic accuracy of clinical tests for ankle syndesmosis injury

Objective: Our aim was to investigate the diagnostic accuracy of the clinical presentation of ankle syndesmosis injury and four common clinical diagnostic tests.

Design: Cross-sectional diagnostic accuracy study.

Setting: 9 clinics in two Australian cities.

Participants: 87 participants (78% male) with an ankle sprain injury presenting to participating clinics within 2 weeks of injury were enrolled.

Methods: Clinical presentation, dorsiflexion-external rotation stress test, dorsiflexion lunge with compression test, squeeze test and ankle syndesmosis ligament palpation were compared with MRI results (read by a blinded radiologist) as a reference standard. Tests were evaluated using diagnostic accuracy, sensitivity, specificity and likelihood ratios (LRs). A backwards stepwise Cox regression model determined the combined value of the clinical tests.

Results: The clinical presentation of an inability to perform a single leg hop had the highest sensitivity (89%) with a negative LR of 0.37 (95% CI 0.13 to 1.03). Specificity was highest for pain out of proportion to the apparent injury (79%) with a positive LR of 3.05(95% CI 1.68 to 5.55). Of the clinical tests, the squeeze test had the highest specificity (88%) with a positive LR of 2.15 (95% CI 0.86 to 5.39). Syndesmosis ligament tenderness (92%) and the dorsiflexion-external rotation stress test (71%) had the highest sensitivity values and negative LR of 0.28 (95% CI 0.09 to 0.89) and 0.46 (95% CI 0.27 to 0.79), respectively. Syndesmosis injury was four times more likely to be present with positive syndesmosis ligament tenderness (OR 4.04, p=0.048) or a positive dorsiflexion/external rotation stress test (OR 3.9, p=0.004).

Conclusions: Although no single test is sufficiently accurate for diagnosis, we recommend a combination of sensitive and specific signs, symptoms and tests to confirm ankle syndesmosis involvement. An inability to hop, syndesmosis ligament tenderness and the dorsiflexion-external rotation stress test (sensitive) may be combined with pain out of proportion to injury and the squeeze test (specific).