Subtalar Arthrodesis with Flexor Digitorum Longus Transfer and Spring Ligament Repair for Treatment of Posterior Tibial Tendon Insufficiency

Abstract

The surgical treatment of flexible pes planovalgus deformities resulting from Stage 2 posterior tibial tendon insufficiency is controversial and many techniques have been proposed. We retrospectively reviewed the results of subtalar arthrodesis combined with spring ligament repair/reefing and flexor digitorum longus (FDL) transfer to the navicular. There were sixteen patients (seventeen feet) with an average follow-up of 27 months (9-52). All deformities were passively correctable. The average age was 56 yrs (39-78). All patients had failed conservative management, 88% had previously been treated with orthotics, and 53% had lateral pain from subfibular impingement. Two patients were noted to have degenerative changes of the subtalar joint. Successful subtalar joint fusion occurred in all patients with an average time to radiographic union of 10.1 weeks (5-24). The average AOFAS hindfoot score and Maryland foot score postoperatively was 82 and 86 respectively. Standing radiographic analysis demonstrated an average improvement in the AP talo-1st metatarsal angle of 6 degrees (24 degrees preoperative, 18 degrees postoperative). The talonavicular coverage angle improved an average of 17 degrees (34 degrees preoperative, 17 degrees postoperative). The lateral talo-1st metatarsal angle improved an average of 10 degrees (18 degrees preoperative, 8 degrees postoperative). The lateral talocalcaneal angle decreased an average of 21o (55 degrees preoperative, 34 degrees postoperative). The distance of the medial cuneiform to the floor on the lateral radiograph averaged 12mm preoperatively and 18mm postoperatively (avg. improvement 6mm). The combination of the flexor digitorum longus tendon transfer and spring ligament repair with subtalar arthrodesis is an effective and reliable procedure which provides excellent correction of hindfoot valgus as well as forefoot abduction and restoration of the height of the longitudinal arch. These results compare favorably with flexor transfer combined with either calcaneal osteotomy or lateral column lengthening.

Arthrodesis Techniques in the Management of Stage-Ii and Iii Acquired Adult Flatfoot Deformity

“…There is support in the literature for the use of isolated subtalar arthrodesis to treat acquired adult flatfoot deformity when the patient has a fixed deformity of the subtalar joint and a flexible forefoot 22,23 . Mann et al stated that 10° to 15° of forefoot varus or joint hypermobility is a contraindication to isolated subtalar joint fusion 10 .…”

“…Johnson et al reported on seventeen feet treated with subtalar joint arthrodesis, reconstruction of the flexor digitorum longus, and repair of the spring ligament 22 . At two years postoperatively, the results compared favorably with those of medial displacement calcaneal osteotomy and lateral column lengthening.…”

“…However, the authors of an in vitro biomechanical study concluded that isolated subtalar or calcaneocuboid fusion cannot achieve full correction of a moderate flatfoot deformity with substantial transverse tarsal joint laxity; in contrast, a talonavicular, double, or triple arthrodesis completely corrected the deformity 24 . We believe that, when an isolated subtalar fusion is performed to treat acquired adult flatfoot deformity, the addition of a flexor digitorum longus transfer helps to support the talonavicular joint and balances the pull of the peroneus brevis 22 .…”

“…Complications included symptomatic arthrosis of adjacent joints, malunion, and nonunion. Others have recommended the addition of a flexor digitorum longus transfer to the navicular in order to help stabilize the talonavicular joint when isolated subtalar arthrodesis is performed for Stage-II disease 22 . The addition of the flexor digitorum longus transfer in the treatment of Stage-II disease may also help to prevent the progressive development of valgus tilt of the ankle after triple arthrodesis, but it has not been widely utilized in that setting.…”

Risk of Neurovascular Injuries in Flexor Hallucis Longus Tendon Transfers: An Anatomic Cadaver Study

“…This can be important when a longer part of tendon is required, such as in procedures for posterior tibial tendon insufficiency where the FHL tendon has to be pulled through a drill-hole in the navicular tuberosity. 6 In the literature covering FHL tendon transfer, little attention has been given to the difficulties that arise while harvesting the FHL tendon. However, when a double-incision technique is used and transection is made distal to the knot of Henry, we observed difficulties in harvesting the FHL tendon because of cross-attachments between FHL and FDL, which required a more extensive dissection.…”