The effect of tibialis posterior tendon transfer on anatomical foot parameters and functional outcomes in drop foot patients: a single center study

This retrospective single-center study aimed to evaluate the anatomical and functional outcomes of tibialis posterior tendon transfer in patients with foot drop. Foot drop is characterized by weakness or loss of ankle dorsiflexion, eversion, and toe extension, commonly resulting from neurological, systemic, or traumatic causes. Tibialis posterior tendon transfer improves ankle dorsiflexion function rather than restoring normal ankle function, and it also eliminates deforming forces on the medial foot. This study aimed to evaluate the anatomical and functional outcomes of tibialis posterior tendon transfer in patients with foot drop. This single-center retrospective study included 20 patients who underwent tibialis posterior tendon transfer via the interosseous membrane between 2016 and 2023. Radiological evaluation included assessment of the tibiotalar angle and hindfoot alignment. Evaluation of the medial longitudinal arch (MLA) was based on measurements of the calcaneus–first metatarsal angle, lateral talus–first metatarsal angle (Meary’s angle), lateral talocalcaneal angle, talohorizontal angle, calcaneal pitch angle, talonavicular coverage angle, anteroposterior (AP) talocalcaneal angle, and AP talus–first metatarsal angle. Surgical success and functional recovery were assessed using the Stanmore score and the criteria described by Carayon et al. The primary endpoint was the postoperative improvement in active dorsiflexion and medial longitudinal arch parameters. The Carayon criteria evaluate active dorsiflexion (DF), active plantarflexion (PF), and active range of motion (ROM). The Stanmore score assesses foot position, active DF, muscle strength grade, functional activities, ability to use normal footwear, orthosis use, and pain. The mean age was 38.25 years (range, 22–80). The mean duration of paralysis was 45.55 months, and the mean follow-up period was 42.6 months. According to the Stanmore score, outcomes were excellent in 30% of patients, good in 30%, fair in 20%, and poor in 20%. The mean postoperative active dorsiflexion gain was 9° (SD ± 5.6). Changes in the lateral talocalcaneal, lateral talus–first metatarsal, and talohorizontal angles showed a significant relationship with the duration of paralysis, indicating a tendency toward MLA collapse; however, no patients developed pes planus or other deformities. Tibialis posterior tendon transfer effectively reduces the need for orthotic devices and achieves satisfactory restoration of active ankle dorsiflexion in patients with foot drop. Careful tension adjustment and proper positioning during surgery are essential for optimal alignment and functional recovery.