Achilles tendon rupture must be excluded in the neutral, non-fractured ankle X-ray study

Background: Rupture of the Achilles tendon (TA) is a common injury. Nevertheless, there is significant potential for missing the diagnosis on initial presentation. We investigated the potential role of lateral ankle X-ray studies in aiding diagnosis.

Objectives: To determine the potential role of radiographs of the ankle in assisting in the diagnosis of Achilles tendon ruptures.

Methods: In a regional trauma unit, 27 patients with confirmed TA rupture at operation had the "tibio-first metatarsal angle" measured as an indication of ankle neutrality. A neutral ankle was defined as an angle of≤100°. Twenty-seven patients with intact TA were used as controls.

Results: The mean angle in the TA rupture group was 88° (range 70-120°) and 125° (104-146°) in the control group (p<0.001).

Conclusions: In cases of TA rupture, the ankle adopts a more dorsiflexed position than in the ankle with an intact TA. We believe that an ankle joint adopting a neutral position on a lateral X-ray study of the ankle provides a clue to help reduce the rate of missed TA ruptures at initial presentation.