Correlation of stress radiographs to injuries associated with lateral ankle instability

ARTICLE HIGHLIGHTS

Research background

Once patients were diagnosed with instability based upon stress radiographs, the surgical procedure was delayed due to the need to obtain a magnetic resonance imaging in order to define which patients had associated conditions. Prior to this study, the surgeons involved felt that higher degrees on instability were associated with the incidence of associated conditions that could result from instability.

Research motivation

In general, we hoped to avoid a delay in treatment due to the need to obtain advanced imaging. We assumed that patients with higher degrees of instability would have osteochondral lesions or peroneal pathology and would require diagnostic arthroscopy or peroneal exploration while patients with a lesser degree of instability could be addressed with a limited surgical procedure focused on the lateral ligaments.

Research objectives

We aimed to determine a degree of instability that could predict the incidence of peroneal pathology or osteochondral defects.

Research methods

A retrospective analysis of patients who had previously been diagnosed with ankle instability was performed. We stratified the patients based upon their degree of instability as defined by stress radiographs and evaluated the incidence of peroneal pathology and osteochondral defects as related to the varying degrees of instability.

Research results

Increasing degrees of instability was associated with a statistically significant increased prevalence of peroneal pathology. An inverse relationship was found between increasing degrees of instability and the presence of osteochondral defects. While we did confirm the association of ligamentous instability to peroneal pathology and the inverse relationship found between osteochondral defects and instability, we did not find a degree of instability that was predictive of peroneal pathology or osteochondral defects.

Research conclusions

Stress radiographs were not found to be predictive of peroneal tendon pathology or osteochondral defects of the talus.

Research perspectives

This is only the second study to demonstrate an inverse relationship between ankle instability and osteochondral defects of the talus. This is a novel discovery, but the injury mechanism that leads to ligamentous instability without chondral injury is unclear. Potentially axial load injuries are more likely to result in chondral injuries as opposed to rotational injuries that may lead to ankle instability. Further work is required to better understand this injury pattern.