Irreducible tongue-type calcaneal fracture due to interposition of flexor hallucis longus.

We present a rare case of interposition of the flexor hallucis longus (FHL) tendon blocking percutaneous closed reduction of a displaced tongue-type calcaneal fracture, and necessitating open repositioning of the tendon and internal fixation through a single extensile lateral approach. Although not recognized until during surgery, with a high index of suspicion, preoperative diagnosis of this injury combination should be possible on high resolution CT, thus enabling better planning of the procedure. The presence of a small sustentacular fragment, especially if markedly displaced or rotated, should further alert the physician as to increased likelihood of such tendon entrapment within the fracture. In the literature, fracture fixation and extrication of the FHL tendon have been performed via either or both lateral and medial approaches. A medial approach may prove necessary when there is severe displacement or rotation of the sustentacular fragment. Arthroscopically assisted surgery may aid in disengaging the tendon from within the fracture site.