Peroneal tendon tear
I had an interesting conversation the other day with a chiropractic student who came in to see me as a patient. He's a 26 y/o male who's very focused on physical fitness. He's in great shape and loves soccer and running. Six months ago he was tackled in a soccer game. The play resulted in what at first seemed like a sprained ankle, except this sprain didn't heal. Interestingly, the patient had no symptoms with pedestrian activities. When he did attempt to return to sports he was limited by peroneal tendon pain. He said that if he went for a recreational run he couldn't play soccer the same day. Or if he played soccer, he wouldn't be able to run for several days.
Clinical exam noted swelling specific to the posterior aspect of the left lateral malleolus. Swelling was specific to the peroneal tendon sheath. There was no crepitus or subluxation of the tendons on range of motion. Plain x-ray revealed no fracture of the fibula or chip fracture associated with a rupture of the peroneal retinaculum. MRI confirmed a longitudinal tear of the peroneus brevis tendon.
The patient had an interesting question. He asked whether the pain that he had now with activity was due to the original injury or whether it was due to a repetitive injury that occurred when he pushed the ankle (like soccer and recreational running in the same day). The original injury occurred when the peroneus longus tendon created a split or longitudinal rupture of the brevis tendon. To understand the mechanism of injury, think of the fibula carrying the patient's body weight like a spear towards the ground and the two peroneal tendons abruptly trying to pull up against this force. I can see how the mechanism of injury actually happened, but was it the original injury that was causing his daily pain? Or does the longitudinal tear contribute to increased degenerative changes in the tendon and subsequent pain?
I'd have to go with the latter. It's not the original injury that hurts but rather the repetitive re-injury that causes chronic pain with peroneal tendon tears. Smart kid. He'll go places with that kind of intellectual curiosity.
Jeffrey A. Oster, DPM