Minimally Invasive Retrograde Method of Harvesting the Flexor Hallucis Longus Tendon: A Cadaveric Study

Abstract

Background: Use of the flexor hallucis longus (FHL) tendon is well described for several tendon augmentation procedures. Harvesting the FHL through an open medial approach is commonly done, but is associated with anatomic risks. Recently, several authors have described a minimally invasive (MI) technique to harvest the FHL tendon utilizing a hamstring tendon stripper commonly used in ACL reconstruction. The purpose of this study was to evaluate the safety and effectiveness of harvesting the FHL tendon using this novel minimally invasive retrograde approach. Methods: The FHL tendon was harvested through a transverse plantar incision over the interphalangeal joint of the great toe in 10 fresh-frozen cadaver lower extremities. A lateral-based incision for peroneal tendon repair was made and the FHL was retrieved. Tendon length, complications, and interconnections between the FHL and flexor digitorum longus (FDL) were recorded and classified. The specimens were then dissected by a single surgeon in a standardized fashion, and damage to any surrounding structures was recorded. Results: The average length of the FHL tendon from the distal stump to the first intertendinous connection was 13.3 cm (range 8.8-16 cm, SD 2.3 cm). Eight cadavers demonstrated Plaass type 1 interconnections whereas 2 demonstrated type 3. There was no injury to the medial and lateral plantar arteries and nerves, plantar plate, or FDL tendons. One FHL tendon was amputated at the level of the sustentaculum during graft harvest. No injury of the medial neurovascular structures occurred with retrieval of the FHL tendon through the lateral incision. Conclusions: We found that care must be taken when approaching the sustentaculum with the tendon harvester in order to avoid amputation of the graft against a hard bony endpoint. Additionally, flexion and extension of the lesser toes could aid in successful tendon harvest when tendon interconnections were encountered. Clinical Relevance: Using this MI technique appears to be a safe and effective way to obtain a long FHL tendon graft for tissue augmentation.