Surgical Planning for Flexor Digitorum Longus Tendon Transfers: An Anatomic Study

Posterior tibial tendon dysfunction is often coupled with various degrees of hindfoot valgus and equinus. Preoperative planning is essential to appropriate procedure choice and surgical efficiency. The purpose of the present study was to assess the anatomy at the harvest site for flexor digitorum longus tendon transfer, specifically at the master knot of Henry. Thirty fresh-frozen below-the-knee cadavers were used for dissection. A standard anatomic approach was performed for posterior tibial tendon debridement and flexor digitorum longus tendon transfer. The flexor digitorum longus tendon was harvested and measured at the master knot of Henry. The present anatomic study evaluated the tendon width of the flexor digitorum longus tendon at a common harvest site. Of the 30 specimens, 20 (67%) measured 5 mm and 10 (33%) measured 4 mm. A 5.0-mm interference screw would be acceptable in each specimen and therefore would be the safest choice. A 4.0-mm interference screw would be acceptable in only 33% of the specimens. Males have a slightly more robust flexor digitorum longus tendon than females at the harvest site. This information will assist surgeons in preoperative planning during stage II flatfoot correction for posterior tibial tendon dysfunction.