Transfer of Soleus Muscular Branch of Tibial Nerve to Deep Fibular Nerve to Repair Foot Drop After Common Peroneal Nerve Injury: A Retrospective Study

SLR - April 2022 - Kira Cramer

Reference: Bao, Bingbo et al. “Transfer of Soleus Muscular Branch of Tibial Nerve to Deep Fibular Nerve to Repair Foot Drop After Common Peroneal Nerve Injury: A Retrospective Study.” Frontiers in neurology vol. 13 745746. 11 Feb. 2022, doi:10.3389/fneur.2022.745746

Level of Evidence: 3

Scientific Literature Review

Reviewed By: Kira Cramer, DPM
Residency Program: Presbyterian St. Luke’s Medical Center – Denver, CO

Podiatric Relevance: Drop foot is a relatively rare condition that may be secondary to common peroneal nerve damage. This is a debilitating condition for patients and surgical repair can be challenging. This study looked at functional outcomes of  muscle strength and nerve activation after using the soleus muscular branch of the tibial nerve as a donor for the deep fibular nerve.

Methods: From January 2017 to December 2019, eight patients underwent nerve transfers for common peroneal nerve damage secondary to high-energy trauma injury and delayed treatment. All patients failed to improve in EMG scores or clinically after six months of conservative care. The British Medical Research Council grading system (M0-M5) was used to measure muscle strength preoperatively and postoperatively as well as EMG testing to evaluate nerve function. Patients with dysfunction or paralysis of the tibial nerve, pre-existing peripheral neuropathy, major posterior compartment injury, or any other lower extremity nerve injuries were excluded.

Results:
●    No patients lost to follow up and all followed for a mean of 24 months.
●    Upon postoperative EMG testing, action potentials were found in the tibialis anterior, extensor hallucis longus, and extensor hallucis longus in all but one patient. Three patients also showed innervation of the soleus muscle.
●    Four patients (50 percent) achieved an ankle dorsiflexion BMRC grade of M3 or greater, one had a grade of M2, two had a grade of M1, and one retained a grade of M0.   
●    Four patients showed good functional recovery after surgery and could walk and participate in activities without ankle-foot orthotics.

Conclusions: There are several options for treating common peroneal nerve injury. This study showed that tibial nerve transfer (of the soleus muscular branch) to the deep fibular nerve may be a viable option for surgical treatment of drop foot. With variable results and a very small study size, more research should be conducted to determine the reproducibility of this technique, but non the less, this may be a promising means to enable patients to ambulate without assistive devices.