Tibialis posterior transfer for foot drop due to central causes: Long-term hindfoot alignment

Background Tibialis posterior transfer (TPT) is the treatment most widely used to palliate foot drop due to dorsiflexor palsy. TPT has been extensively studied in patients with peripheral neurological causes of foot drop. In contrast, data are scarce on central foot drop, in which TPT is often blamed for causing flattening of the arches. The primary objective of this study was to assess the impact on foot alignment of TPT in patients with central foot drop. The secondary objective was to determine whether TPT combined with other surgical procedures improved gait. Hypothesis TTP can induce flattening of the medial arch of the foot. Patients and Methods We retrospectively identified 13 patients managed with TPT (1 foot per patient). Mean follow-up was 65 months (range, 12–108 months). The causes were stroke (n = 5), head injury (n = 3), spinal cord injury (n = 2), cervical spondylotic myelopathy (n = 1), cerebral palsy (n = 1), and a brain tumour (n = 1). The clinical assessment focused chiefly on forefoot alignment and footprint parameters. The following variables were collected from weight-bearing radiographs: Djian-Annonier angle, Meary-Tomeno angle, lateral arch angle, and calcaneal pitch angle in the sagittal plane; talo-metatarsal angle in the transverse plane; and rearfoot valgus angle in the coronal plane. Results Of the 13 feet, 6 had normal footprint parameters and 7 pes cavus. There were no cases of flatfoot. Pronation deformities and supination deformities were each found in 2 patients. Comparing the radiographic parameters between the two feet in each patient identified differences only for the lateral arch angle and calcaneal pitch angle, which indicated pes cavus on the operated side (operated side: 142.7° [range, 136°–156°], p = 0.041; and 24° [range, 14°–33°], p = 0.028, respectively). Discussion In contrast to the working hypothesis, we found no evidence of progression to valgus flatfoot after TPT transfer performed to treat central foot drop. Level of evidence IV, retrospective study with no control group.