Nerve transfers for femoral nerve palsy: an updated approach and surgical technique

Contemporary Approaches to Peripheral Nerve Surgery

"State of the Art" Learning Objectives: This manuscript serves to provide the reader with a general overview of the contemporary approaches to peripheral nerve reconstruction as the field has undergone considerable advancement over the last 3 decades. The learning objectives are as follows: To provide the reader with a brief history of peripheral nerve surgery and some of the landmark developments that allow for current peripheral nerve care practices.To outline the considerations and management options for the care of patients with brachial plexopathy, spinal cord injury, and lower extremity peripheral nerve injury.Highlight contemporary surgical techniques to address terminal neuroma and phantom limb pain.Review progressive and future procedures in peripheral nerve care, such as supercharge end-to-side nerve transfers.Discuss rehabilitation techniques for peripheral nerve care.

Assessment, management, and rehabilitation of traumatic peripheral nerve injuries for non-surgeons

Electrodiagnostic evaluation is often requested for persons with peripheral nerve injuries and plays an important role in their diagnosis, prognosis, and management. Peripheral nerve injuries are common and can have devastating effects on patients' physical, psychological, and socioeconomic well-being; alongside surgeons, electrodiagnostic medicine specialists serve a central function in ensuring patients receive optimal treatment for these injuries. Surgical intervention-nerve grafting, nerve transfers, and tendon transfers-often plays a critical role in the management of these injuries and the restoration of patients' function. Increasingly, nerve transfers are becoming the standard of care for some types of peripheral nerve injury due to two significant advantages: first, they shorten the time to reinnervation of denervated muscles; and second, they confer greater specificity in directing motor and sensory axons toward their respective targets. As the indications for, and use of, nerve transfers expand, so too does the role of the electrodiagnostic medicine specialist in establishing or confirming the diagnosis, determining the injury's prognosis, recommending treatment, aiding in surgical planning, and supporting rehabilitation. Having a working knowledge of nerve and/or tendon transfer options allows the electrodiagnostic medicine specialist to not only arrive at the diagnosis and prognosticate, but also to clarify which nerves and/or muscles might be suitable donors, such as confirming whether the branch to supinator could be a nerve transfer donor to restore distal posterior interosseous nerve function. Moreover, post-operative testing can determine if nerve transfer reinnervation is occurring and progress patients' rehabilitation and/or direct surgeons to consider tendon transfers.

Free functional muscle transfer for lower extremity reconstruction

BACKGROUND

Free functional muscle transfer is a reconstructive strategy for the reconstruction of lost muscle units in the lower extremity after oncologic resection, trauma, compartment syndrome, or severe nerve injuries. Under appropriate circumstances, free functional muscle transfer may be the only suitable reconstructive option. This article reviews the underlying principles of free functional muscle transfer, its application to lower extremity reconstruction, appropriate patient selection, and surgical techniques.

METHODS

The underlying principles of free functional muscle transfer, its application to lower extremity reconstruction, appropriate patient selection, and surgical techniques are presented. Commonly used donor muscles appropriate for each type of functional defect are discussed. A review of recent publications on free functional muscle transfer in the lower extremity was also performed.

RESULTS

Good functional recovery with a Medical Research Council grade of up to 4/5 and full range of motion can be attained with free functional muscle transfer. Clinical outcomes and specific parameters for published case series in lower extremity free functional muscle transfer are presented and an illustrative case.

CONCLUSION

Free functional muscle transfer is a suitable treatment for the appropriate patient to restore essential functions and potentially regain ambulation. However, additional published clinical outcomes are needed and represent a major area for further investigation.

Resect, rewire, and restore: Nerve transfer salvage of neurological deficits associated with soft tissue tumors in a retrospective cohort series at a tertiary reconstructive center

AIMS

We aimed to explore the effectiveness of nerve transfer as an intervention to restore neurological deficits caused by extremity tumors through direct nerve involvement, neural compression, or as a consequence of oncological surgery.

METHODS

A retrospective cohort study of consecutive cases was conducted, including all patients who underwent nerve transfers to restore functional deficits in limbs following soft tissue tumor resection. The threshold for a successful nerve transfer was a BMRC motor grade of 4/5 and sensory grade of 3-3+/4 with protective sensation.

RESULTS

In total, 29 nerve transfers (25 motor and 4 sensory) were completed in 11 patients, aged 12-70 years at referral, over a 6-year period to 2020. This included 22 upper limb and 3 lower limb motor nerve transfers. The timing of delayed nerve transfer reconstructions was 1-15 months following primary oncological resection, with immediate simultaneous reconstructions performed in 4 cases. The threshold for success was achieved in 82% of upper limb and 33% of lower limb motor nerve transfers, while all sensory transfers were successful in restoring protective sensation.

CONCLUSION

Nerve transfer surgery, a well-established technique in restoring deficits following traumatic nerve injury, is further demonstrably relevant in extremity oncological reconstruction, especially as it can be performed remotely to the tumor location or resection site and introduces a healthy nerve or fascicle to rapidly reinnervate distal muscles without sacrificing major function. This study further illustrates the importance of early recognition and referral to specialist services where multi-disciplinary surgical resection and reconstructive planning can be conducted.

LEVEL OF EVIDENCE

IV Clinical Case Series.

Perineurial Window is Critical for Experimental Reverse End-to-Side Nerve Transfer

BACKGROUND

The depth of connective tissue window in the side of a recipient nerve in reverse end-to-side transfers (RETS) remains controversial.

OBJECTIVE

To test whether the depth of connective tissue disruption influences the efficiency of donor axonal regeneration in the context of RETS.

METHODS

Sprague-Dawley rats (n = 24) were assigned to 1 of the 3 groups for obturator nerve to motor femoral nerve RETS: group 1, without epineurium opening; group 2, with epineurium only opening; and group 3, with epineurium and perineurium opening. Triple retrograde labeling was used to assess the number of motor neurons that had regenerated into the recipient motor femoral branch. Thy1-GFP rats (n = 8) were also used to visualize the regeneration pathways in the nerve transfer networks at 2- and 8-week time point using light sheet fluorescence microscopy.

RESULTS

The number of retrogradely labeled motor neurons that had regenerated distally toward the target muscle was significantly higher in group 3 than that in groups 1 and 2. Immunohistochemistry validated the degree of connective tissue disruption among the 3 groups, and optical tissue clearing methods demonstrated donor axons traveling outside the fascicles in groups 1 and 2 but mostly within the fascicles in group 3.

CONCLUSION

Creating a perineurial window in the side of recipient nerves provides the best chances of robust donor axonal regeneration across the RETS repair site. This finding aids nerve surgeons by confirming that a deep window should be undertaken when doing a RETS procedure.

Motor and sensory nerve transfers in the lower extremity: Systematic review of current reconstructive possibilities

BACKGROUND

Peripheral nerve injuries (PNI) are predominantly treated by anatomical repair or reconstruction with autologous nerve grafts or allografts. Motor nerve transfers for PNI in the upper extremity are well established; however, this technique is not yet widely used in the lower extremity. This literature review presents an overview of the current options and postoperative results for nerve transfers as a treatment for nerve injury in the lower extremity.

METHODS

A systematic search in PubMed and Embase databases was performed. Full-text English articles describing surgical procedures and postoperative outcomes of nerve transfers in the lower extremity were included. The primary outcome was postoperative muscle strength measured using the British Medical Research Council (MRC) scale, with MRC> 3 considered good and postoperative return of sensation reported according to the modified Highet classification.

RESULTS

A total of 36 articles for motor nerve transfer and 7 for sensory nerve transfer were included. Sixteen articles described motor nerve transfers for treating peroneal nerve injury, 17 for femoral nerve injury, 2 for tibial nerve injury, and one for obturator nerve injury. Transfers of multiple branches to restore deep peroneal nerve function led to a good outcome in 58% of patients and 43% when a single branch was used as a donor. The transfer of multiple branches for femoral nerve or obturator nerve repair was performed in all reported patients with a good outcome.

CONCLUSIONS

The transfer of motor nerves for the recovery of PNI is a feasible technique with relatively low risks and great benefits. The correct indication, timing, and surgical technique are essential for optimizing results.

A Systematic Review of Muscle Synergies during a Walking Gait to Define Optimal Donor-Recipient Pairings for Lower Extremity Functional Reconstruction

Functional lower extremity reconstruction primarily aims to restore independent ambulation. We sought to define the synergies recruited during a walking gait to inform donor selection for various motor deficits. With these findings, we discuss the functional neuromuscular components of independent gait with the goal of informing lower extremity reconstruction.