Posterior Tibial Tendon Allograft Reconstruction for Stage II Adult Acquired Flatfoot: A Case Series.

Surgical treatment for a stage II adult acquired flatfoot has consisted of reconstruction of the diseased posterior tibial tendon with flexor digitorum longus tendon transfer, combined with osteotomies to address the underlying deformity. This case series presents an alternative to tendon transfer using allograft tendon for posterior tibial tendon reconstruction. Four patients who underwent stage II flatfoot reconstruction with posterior tibial tendon allograft transplantation were included. All patients had preoperative radiographs demonstrating flatfoot deformity and magnetic resonance imaging showing advanced tendinopathy of the posterior tibial tendon. Allograft tendon transplant was considered in patients demonstrating adequate posterior tibial tendon excursion during intraoperative assessment. Additional procedures were performed as necessary depending on patient pathology. Postoperatively, all patients remained non-weightbearing in a short leg cast for 6 weeks. Radiographs performed during the postoperative course demonstrated well-maintained and improved alignment. No complications were encountered. Each patient demonstrated grade 5 muscle strength and were able to perform a single-limb heel rise at the time of final follow-up. The average follow-up duration was 19.0 months. Flexor digitorum longus transfer has been studied extensively for stage II adult acquired flatfoot. However, the flexor digitorum longus has been shown to be much weaker relative to the posterior tibial tendon, and concern remains regarding its ability to recreate the force of the posterior tibial tendon. Our results demonstrate that posterior tibial tendon allograft reconstruction combined with flatfoot reconstruction is a reasonable option. This alternative has the advantage of preserving the stronger muscle without disturbing regional anatomy.