Abstract
Peroneal tendon tear is a relatively common cause of lateral ankle pain but often missed due to mixed presentation or low index of suspicion. Left untreated, peroneal injuries can lead to persistent ankle pain, instability and ultimately substantial functional disabilities. An isolated peroneus longus tear is rare with the lowest incidence rate compared to isolated peroneus brevis tear and mixed tear of both peroneal tendon. This is a case report of a 49-year-old lady with a chronic left ankle pain who ultimately underwent surgery for an isolated peroneus longus tear.
Highlights
The peroneal muscles are the pronators and evertors of the foot
Peroneal disorder is an under-diagnosed cause of lateral ankle pain where the commonest among peroneal pathology is isolated peroneus brevis tear (70%) followed by mixed peroneal tear (21%) and isolated peroneus longus tear (9%)[4]
Clinical findings can be vague and the result from magnetic resonance imaging (MRI) at times are not accurate, as suggested from our case of an isolated peroneus longus tear being reported as mixed peroneal tendinopathy
Summary
The peroneal muscles are the pronators and evertors of the foot. They act as a dynamic stabiliser of the ankle joint and are important in maintaining proprioception of the foot independent of the status of lateral ankle ligaments. A compromised peroneal function may lead to a sense of instability and eventually causing persistent pain and occasional swelling of the ankle. The true incidence of peroneal tendon tears is unknown, an estimated range is from 11% to 37% in cadaveric dissections and up to 30% in patients undergoing surgery for ankle instability[1,2].
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