The Science of Peroneal Tendinopathy
Peroneal tendinopathy affects the fibularis longus and brevis tendons that run behind your lateral malleolus (outer ankle bone). These tendons are crucial for ankle stability, particularly during walking on uneven surfaces, and help prevent ankle sprains by providing lateral stability. The peroneal tendons are subject to significant mechanical stress as they navigate around the sharp posterior edge of the fibula, held in place by the superior peroneal retinaculum. This anatomical arrangement makes them vulnerable to friction and degenerative changes, particularly when the retinaculum is damaged or when there are underlying biomechanical issues. Tendinopathy develops when the cumulative load on these tendons exceeds their adaptive capacity. This leads to a failed healing response characterized by disorganized collagen, increased ground substance, and neovascularization. The result is a painful, thickened tendon with reduced mechanical properties. The condition often develops in conjunction with chronic ankle instability, where recurrent ankle sprains lead to peroneal muscle weakness and altered biomechanics. This creates a cycle where weak peroneals increase ankle instability, leading to further tendon stress and degeneration.
Contributing Factors
Your peroneal muscles serve dual roles as foot everters and ankle lateral stabilizers. The fibularis longus also supports your medial longitudinal arch, while the fibularis brevis provides dynamic stability against ankle inversion.
During the stance phase of walking, your peroneal muscles work eccentrically to control inversion and provide lateral stability. On uneven surfaces or during cutting movements in sports, these demands increase dramatically, making the tendons vulnerable to overuse injury.
The peroneal tendons must navigate a sharp turn around the lateral malleolus, similar to a rope moving around a pulley. This creates high friction forces, especially when ankle motion increases or when there are anatomical variations like a prominent peroneal tubercle.
When ankle proprioception is impaired following sprains, the peroneal muscles must work harder to provide conscious and subconscious stability. This increased demand, combined with potential weakness from previous injuries, creates the perfect environment for tendinopathy development.