Comparative study of flexor hallucis longus tendon length through single incision or accessory plantar medial incision: a cadaver study

Background: Flexor hallucis longus (FHL) tendon transfer to the calcaneus is used in treatment of Achilles pathology. Tendon harvest is through a posterior or medial incision. This study quantified the tendon length obtained through each technique. Methods: Seven pair-matched cadaver legs were used. One leg was randomly selected for posterior harvest, and the contralateral leg was selected for medial harvest. A dorsal to plantar calcaneus tunnel was prepared. Two tendon measurements were obtained: the total and the functional tendon length. Results: Using a posterior incision, the total and functional tendon lengths were 4.2 cm and 4.0 cm, respectively. Using the medial incision, the total and functional tendon lengths were 8.2 cm and 7.2 cm, respectively. Conclusions: The single incision provided length to anchor the FHL into the calcaneus suggesting this technique is adequate for fixation with an interference screw. For other indications, the medial incision provides additional 4.0 cm (P=0.003) total length or 2.9 cm (P=0.0016) functional length.