Peroneal tendon dislocation is a rare and often overlooked condition, particularly when coexisting with Achilles tendon rupture. It can lead to persistent pain and instability if overlooked. Therefore, an accurate diagnosis in the acute phase is crucial. Both injuries share a similar mechanism, making simultaneous occurrence possible, but difficult to diagnose. This set of patient cases is based on two older male patients that had chronic Achilles tendon rupture and peroneal tendon dislocation following low-energy trauma. Owing to the gait disturbance caused by the Achilles tendon rupture, a peroneal tendon dislocation was overlooked. Sonography provided critical diagnostic information and identified tendon instabilities that magnetic resonance imaging (MRI) could not detect. This case series emphasizes the value of dynamic sonography, in evaluating peroneal tendon instability, especially when symptoms persist or when MRI findings are inconclusive. Clinicians should have a high index of suspicion for combined injuries, even after minor trauma, to ensure accurate diagnosis and appropriate surgical intervention.
Hayashi et al. (2026) studied this question.