Isolated dislocation of the posterior tibial tendon in an amateur snowboarder: a case report.

Isolated dislocation of the posterior tibial tendon is an uncommon pathologic entity that typically occurs in the setting of acute trauma. The diagnosis remains challenging and is often delayed second to the rarity of the injury and symptoms similar to that of medial ankle sprains and other routinely diagnosed injuries about the ankle. The factors that predispose this tendon to dislocation include a hypoplastic retromalleolar groove, flexor retinaculum insufficiency, chronic repetitive trauma, and a structural abnormality from a previous medial malleolar fracture, or a combination thereof. Dislocation has also been cited as a complication of multiple local steroid injections and tarsal tunnel release. The mechanism of injury appears to involve forced dorsiflexion and eversion of the ankle when the posterior tibial tendon is contracted. Most cases do not respond well to conservative treatment and will require surgery to restore function and eliminate symptoms. We report a case of posterior tibial tendon dislocation related to a snowboarding injury and offer our technique for surgical correction.