Avulsion of the flexor retinaculum associated with dislocation of the posterior tibialis and flexor digitorum longus tendons – Don't let a fracture make you miss the diagnosis

•Dislocation of posterior tibialis and flexor digitorum longus tendon is rare.•The diagnosis is difficult but can be made through a careful physical examination.•An avulsion of the flexor retinaculum can be easily reinserted with suture anchors.•If the retromalleolar groove has enough depth, no other gestures seem necessary.•The problem is not the treatment but lack of awareness of this condition. Introduction: Traumatic dislocation of the posterior tibial tendon (PTT) is portrayed as a rare and challenging to diagnose lesion, even more so in association with flexor digitorum longus tendon (FDL) dislocation. This article aims to bring awareness to this condition and present a reasonable and reproducible surgical solution. Case report: A 19-year-old male was admitted after a car accident. An isolated posterior malleolus fracture was identified among other lesions, and surgery was proposed. A cord-like structure over the medial malleolus was identified during surgery, and a PTT and FDL dislocation was diagnosed. The flexor retinaculum was avulsed and was re-inserted with suture anchors, and the tendons remained stable without any additional gesture. At follow-up, good results were obtained. Discussion: PTT dislocations probably occur more frequently than thought, but the association with flexor digitorum longus tendon dislocation seems even rarer. This entity should be known by the common trauma professional since it can be mistaken for an ankle sprain or not noticed in a polytrauma patient. This case brings awareness to vital signs to not miss the diagnosis and a reliable, easy, and reproducible surgical option.