Gastrocnemius Transfer for Foot Drop versus Traditional Tibialis Posterior Transfer: Results from a Long-term Follow-up in a Randomized Controlled Trial

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BACKGROUND: Traditional methods of treating patients with foot drop include tibialis posterior muscle and peroneus longus muscle transfer. Although still considered as the gold standard, tibialis posterior transfer is often associated with inadequate dorsiflexion, ankle instability as well as difficulty in walking without support or splint. This is because the forces generated by the posterior group of muscles are far greater than the anterior ones, and simple transfer of the relatively weak tibialis posterior is insufficient to counteract this difference. In this study, we use gastrocnemius muscle to neutralize the cumulative forces of posterior compartment by transferring it to the anterior compartment. METHODS: Thirty-eight patients were included in this study conducted between 2016 and 2020. They were randomly divided into two equal groups. The patients in the group A underwent transfer of the lateral, medial, or both heads of the gastrocnemius muscle to the tendons of anterior compartment. On the other hand, the patients in the group B underwent the standard transfer of the tibialis posterior tendon to the anterior compartment by fixing it to one of the tarsal bones. Patients were followed up for at least 1 year to assess range of motion, toes movement, and ability to walk without splint or support. Further, functional assessment was done by utilizing the American Orthopaedic Foot & Ankle Society score. RESULTS: Fifteen patients in group A showed excellent results with a good active range of motion of >40 degrees showing no signs of ankle instability and were able to walk without support or splint with no inversion or eversion abnormalities. Two patients were recorded to have good results with >30 degrees of active range of motion. They were able to walk without support and a stable gait. In one case treated with unilateral gastrocnemius, the patient suffered from recurrence. He underwent the opposite gastrocnemius transfer and was ultimately able to walk without support. Active dorsiflexion in patients treated in group A was 17.1 ± 1.3 as opposed to 8.8 ± 1.9 in group B; this difference was significantly better in group A (P < 0.01). Similarly mean active range of motion in group A was 47.2 in group A compared with 38.6 in group B, the difference being significant (P < 0.01). Mean American Orthopaedic Foot & Ankle Society scores significantly improved from 63.4 to 87.8 in the group A and from 65.4 to 70.2 points at final follow-up, denoting that the results were significantly better in the former group (P < 0.001). CONCLUSIONS: Surgical failure and recurrence in patients undergoing standard procedures for foot drop is a commonly found problem. Transferring gastrocnemius muscle to the tendons of anterior compartment not only improves postoperative dorsiflexion with good range of motion, but also provides a stable ankle that allows the patient to walk without a splint or support. This technique should be utilized more often in treating patients with foot drop because it gives better long-term results with no postoperative complications.