The manual stress test may not be sufficient to differentiate ankle ligament injuries.

OBJECTIVE

To assess the accuracy of stress tests (anterior drawer, talar tilt) in the diagnosis of lateral ligament injuries.Design. Stress tests were performed in vitro, and rotation and displacement of the calcaneus relative to the tibia were measured.

BACKGROUND

Stress tests are commonly used to diagnose ankle injuries. However, it is controversial as to whether stress tests can accurately differentiate between isolated anterior talofibular ligament injuries and combined anterior talofibular and calcaneofibular ligament injuries.

METHODS

Stress tests were performed in vitro under three conditions with both ligaments intact, after sectioning the anterior talofibular ligament, and after sectioning the anterior talofibular and calcaneofibular ligament. Motion of the calcaneus relative to the tibia was measured in neutral and in 20 degrees of plantarflexion at the ankle.

RESULTS

There were statistically significant differences among cadavers, examiners and positions. There was a difference between isolated anterior talofibular ligament sectioning and combined anterior talofibular and calcaneofibular ligament sectioning in lateral tilt but not in anterior displacement. In contrast, a difference was found between intact and anterior talofibular ligament sectioned specimens in anterior displacement but not in lateral tilt. However the differences were not great enough to differentiate between the two conditions.

CONCLUSIONS

Each of the stress tests provides reasonable hindfoot displacement but neither is sufficient for accurate diagnosis of specific ligament involvement due to the large amount of individual variation.

RELEVANCE

Many clinicians rely on stress tests to diagnose lateral ligament injuries and to assess the extent of anatomic disruption. This in vitro study has demonstrated poor correlation between clinical stress tests and the degree of ligamentous disruption.