Point-Counterpoint: Is The Flexor Digitorum Longus Tendon Transfer Effective For Stage 2 Adult-Acquired Flatfoot?

Author(s): 
William T. DeCarbo, DPM, AACFAS; Lawrence A. DiDomenico, DPM, FACFAS, Ramy Fahim, DPM, AACFAS, and Zachary Thomas, DPM

   These studies do not, however, explain the extent of involvement of the flexor digitorum longus transfer in maintaining longitudinal arch and transverse plane correction, specifically on a long-term basis.

   Lateral column lengthening and posterior tibial tendon augmentation. Evans originally described this procedure in the pediatric population and with the use of a tricortical graft.11 Correction of this deformity occurs by adducting and plantarflexing the midfoot around the talar head. Hinterman and Toolan and their respective coworkers showed promising results in their case series.12,13 However, other level IV studies have reported complications of forefoot varus, lateral column overload, nonunion and graft failure.14

   Double calcaneal osteotomies and posterior tibial tendon augmentation. The combination of osteotomies provides a powerful correction and further decreases the load on the posterior-medial structures in comparison to single osteotomy procedures. In doing so, there is also improvement in overall alignment of the forefoot on the midfoot. Moseir-LaClair and colleagues demonstrated this point in their case series as well.15 However, the authors drew no direct conclusion regarding the individual benefit of the flexor digitorum longus tendon transfer in this procedure.

   With a double calcaneal osteotomy, there is a greater potential for realignment and thus the need for the flexor digitorum longus tendon transfer as an augmentation for the posterior tibial tendon is questionable. In fact, the question of how much structural support the flexor digitorum longus tendon transfer provides is unanswered in lieu of using more predictable osteotomies that provide powerful deformity corrections in three planes.

What You Can Learn From The Authors’ Surgical Approach

In addition to ensuring supine positioning of the patient on the operating table and the use of general anesthesia, one may use an ipsilateral pneumatic thigh tourniquet to aid hemostasis. We perform a repeat Silfverskiold test intraoperatively to confirm clinical testing.16 In our experience, approximately 90 percent of patients have presented with isolated gastrocnemius equinus when presenting with symptomatic PTTD. One can address the posterior muscle group contracture by either a gastrocnemius recession (endoscopic or open), or a tendo-Achilles lengthening, which is dictated by the Silfverskiold test results.

   Then execute extra-articular osteotomies of the hindfoot via a medializing percutaneous calcaneal displacement osteotomy.17 Use a Gigli saw to execute the osteotomy. The surgeon then evaluates the midtarsal joint intraoperatively. If the midtarsal joint is unstable with the subtalar joint in a neutral position, perform an Evans osteotomy through an oblique lateral incision with the use of a tricortical allograft.

   The fixation of our choice is through two large partially threaded cancellous cannulated screws. We employ an interfragmentary compression screw, partially threaded, in the superior calcaneus compressing the calcaneal displacement osteotomy. Insert a second screw in the inferior portion of the calcaneus. This screw is a large, “dual use,” long-thread, cannulated, cancellous screw to compress the calcaneal slide osteotomy. The distal portion of the screw functions as a positional screw that maintains the Evans correction without compression while the proximal portion of the screw provides interfragmentary compression. This approach allows us to achieve a significant amount of correction with minimal dissection to the medial and lateral soft tissues through the use of intramedullary fixation. The double calcaneal osteotomy with gastrocnemius recession also allows the surgeon to preserve the essential hindfoot joints while permitting realignment arthrodesis of the nonessential joints of the midfoot as necessary.

   Then evaluate the medial column and address it for hypermobility at the affected joints. Stabilize the identified instability/deformity through a medial approach. In doing so, one stabilizes the first ray and positions it to create a tripod effect.

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