Radial nerve palsy is a devastating condition that may present with a combination of loss of elbow extension, wrist extension, or finger extension depending on the level of injury. These palsies may arise from myriad etiologies, ranging from spinal cord and brachial plexus injuries to idiopathic and inflammatory conditions. The purpose of this chapter is to present nerve transfers as an emerging approach to radial nerve deficits. We also present principles and evidence for alternative treatment strategies, including primary repair, nerve grafting, and tendon transfers.
Introduction
The radial nerve is the primary wrist and digital extensor and palsy results in critical loss of function. Injury can occur in the setting of direct trauma, traction injuries, or compression. Nerve transfers have recently emerged and been popularized as a surgical alternative to tendon transfer to restore function. This review discusses the history, outcomes, alternatives, and surgical techniques involved in nerve transfers for radial nerve palsy.
Anatomy
To understand the basis for nerve transfers, it is crucial to review the anatomy of the radial nerve. The radial nerve is the main terminal branches of the posterior cord of the brachial plexus with contributions from C5-T1. The nerve passes around teres major through the triangular interval with the profunda brachii artery to enter the posterior compartment of the arm. It gives off branches to the triceps as it courses inferiorly and posteriorly between the long and medial heads of the triceps muscle around the humerus within the spiral groove exiting through the lateral intermuscular septum. The radial nerve then enters the anterior compartment of the arm 10-12 cm proximal to the lateral epicondyle. It sends branches to the brachioradialis and extensor carpi radialis longus before bifurcating into the sensory and motor posterior interosseous nerve (PIN) branches 2-3 cm proximal to the lateral epicondyle. Occasionally the radial nerve proper also innervates the extensor carpi radialis brevis. The branches course together and cross the elbow at the radiocapitellar joint. The posterior interosseus nerve dives under the arcade of Frohse at the proximal edge of the supinator where the motor branch gives supply to the muscle. After emerging from the supinator, the PIN branches into a superficial and deep branch—the superficial branch innervates the extensor digitorum communis, extensor carpi ulnaris, and extensor digiti minimi; whereas the deep branch innervates the abductor pollicus longus, extensor pollicus brevis, extensor pollicus longus, and extensor indices proprius. The posterior interosseous branch finally courses along the dorsal interosseous membrane and terminates at the level of the carpus with intraarticular innervation. The dorsal sensory branch diverges in course just distal to the elbow and courses on the underside of the brachioradialis muscle belly. Near the mid forearm (approximately 8 cm proximal to the radial styloid), it passes from the volar forearm compartment to the dorsal compartment below the brachioradialis tendon and continues on to supply the sensation of the dorsoradial aspect of the hand.
Pathology
The level at which the radial nerve injury occurs determines the subsequent dysfunction and disability. If the radial nerve is injured in the axilla (e.g. secondary to traction or direct blunt trauma/laceration), then the patient will lose extension of the elbow, wrist and digits as well as sensory changes in the dorsal radial hand. If the injury occurs mid-humerus (which perhaps is the most common scenario in the setting of a humeral shaft fracture), then the patient will maintain elbow extension function, but will not have wrist/digital extension at the metacarpophlangeal (MCP) joint nor will they have sensation in the dorsal radial hand. Finally, if the injury occurs distal to the elbow joint and is limited to the posterior interosseus nerve (such as in the case of an iatrogenic PIN injury during distal biceps repair surgery), then the patient will maintain wrist extension but will lose digital extension at the MCP joint. While trauma (traction, compression, or laceration) is the most common mechanism of radial nerve palsy, it is possible to have atraumatic radial nerve pathology as well. Idiopathic or mass-induced compression can occur, most commonly at the level of the spiral groove, intermuscular septum, the radial recurrent vessels in the proximal forearm (the “leash of Henry”), and the arcade of Frohse. Isolated PIN palsies have been describe in association with rheumatoid arthritis. Finally, virus-induced and other nonmechanical etiologies of radial nerve injury are also possible. ,
History in the Management of Radial Nerve Palsy
Historically radial nerve palsy management involved nonoperative management with splinting and therapy. However, with the advent of advanced surgical techniques in the 20th century, viable surgical options developed. Sharp injuries to the radial nerve may enable primary repair with or without nerve graft. However, if the level of the injury is high and the time to surgical repair is delayed, distal motor recovery may not be possible (assuming 1 mm/day nerve regeneration and approximately 12-18 months before motor end plate scarring occurs. Therefore, tendons transfers have been the mainstay of treatment for radial nerve palsies that do not show functional recovery. They still remain the gold standard for treatment and reconstruction for restoring wrist extension and digital extension after radial nerve palsy as they have consistently demonstrated improved patient function. However there are some limitations with tendon transfers, namely related to the lack of restoration of independent digital extension, bowstringing, and unintended wrist or finger imbalance.
In 2002, Lowe, Tung, and McKinnon described a novel technique for managing radial nerve paralysis with nerve transfers. They detailed 2 case reports of transfer of redundant branches of the median nerve to the flexor digitorum superficialis into the posterior interosseous nerve. In a follow-up publication by Brown et al., authors described a detailed technical description of additional median nerve donors, including branches flexor carpi radialis, and palmaris longus.
Indications for Nerve Transfers
Nerve transfers are indicated for radial nerve palsy when spontaneous recovery is not expected, or when direct repair or grafting is impractical given high level of injury. If conservative measures fail to produce functional recovery after 3-6 months, and electromyography (EMG) studies suggest poor regeneration potential, surgical exploration and intervention is reasonable. Contraindications to performing nerve transfers for radial nerve palsy include poor donor nerve quality (most commonly due to concomitant injury), poor radial motor nerve targets (as may be the case after local trauma or with intrinsic pathology such as axonal disease), donor strength of Medical Research Council (MRC) grade 4 or less (to prevent substantial downgrading of donors), or prolonged time from injury such that the muscle targets are no longer suitable to reinnervate (usually due to prolonged duration between time to injury and expected muscle reinnervation after nerve transfer).
Surgical Anatomy and Techniques for Nerve Transfers in Radial Nerve Palsy
Surgical Anatomy for Nerve Transfers
Achieving successful nerve transfer for radial nerve palsy depends on a detailed understanding of both donor and recipient nerve anatomy. The donor nerves are carefully selected based on their expendability, proximity to the target muscle groups, and ease of transfer ( Table 1 ).
| Donor | Recipient | Restores |
|---|---|---|
| Ulnar nerve | Radial nerve | |
| Branch to Flexor Carpi Ulnaris (FCU) | Branch to Triceps | Elbow Extension |
| Median Nerve | ||
| Branch to Pronator Teres (PT) | Branch to Extensor Carpi Radialis Longus(ECRL) | Wrist Extension |
| Branch to Extensor Carpi Radialis Brevis (ECRB) | ||
| Branch to Flexor Digitorum Superficialis (FDS) | ||
| Branch to Pronator Quadratus (PQ) | ||
| Branch to Flexor Carpi Radialis (FCR) | Posterior Interosseous Nerve (PIN) | Finger and Thumb Extension |
| Supinator |
Donor and Recipient Nerves in Nerve Transfers
Several donor nerves are commonly used in nerve transfers for radial nerve palsy. Among the median nerve motor branches, the branches to the flexor carpi radialis (FCR) and flexor digitorum superficialis (FDS) are frequently selected due to their expendability, as other muscles can compensate for their functions. , Branches to the pronator quadratus and pronator teres have also been described as viable donor option. , In unique circumstances, such as lower trunk brachial plexus injuries, branches from the supinator may be used to reinnervate the posterior interosseous nerve (PIN). ,
The radial nerve branches responsible for wrist and finger extension are the primary targets in these procedures. Specifically, the PIN is addressed for finger and thumb extension, while the branches to the extensor carpi carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB) are targeted to restore wrist extension. ,
Nerve Transfer Techniques
Nerve transfers for radial nerve palsy aim to restore wrist and finger extension, significantly improving hand function. Two primary approaches are commonly employed:
Median to Radial Nerve Transfer
The median to radial nerve transfer is one of the most commonly performed procedures for radial nerve palsy, utilizing the redundancy of certain median nerve branches to restore function. The donor nerves are typically the branches to the flexor carpi radialis (FCR) or flexor digitorum superficialis (FDS), while the recipient nerves are the branches to the ECRB for wrist extension and the PIN for finger and thumb extension.
The procedure begins with the creation of a curvilinear incision along the proximal radial forearm to expose the median and radial nerves. The lacertus fibrosus is identified and divided, the pronator teres is then retracted medially, revealing the underlying median nerve. Of note, the radial vessels lie lateral to the median nerve; which serves as an important dividing landmark between the donor and recipient nerves. The median nerve is then neurolysed distally towards the deep head of pronator teres (PT) and through the FDS arch. As the median nerve is followed, it will first give of branches to the superficial and deep heads of pronator teres. More distally the median nerve gives off branches to FCR, PL, and FDS, all of which should come off along the ulnar aspect of the nerve. The anterior interosseous nerve (AIN), topographically sits on the posterior aspect of the median nerve. Care must be made to identify the AIN to preserve the function of the flexor pollicus longus (FPL). A nerve stimulator is crucial during this step to identify suitable donor nerves and assess their functionality. If the muscle does not respond normally to stimulation, alternative donor options should be considered. Once identified, the motor branch to the FCR, PL or FDS is dissected and divided distally near the muscle belly entry points.
At this time, the radial nerve recipients are now identified. Dissection occurs now lateral to the radial vessels. The brachioradialis is retracted laterally, and the radial sensory nerve is identified. The sensory branch can be traced proximally back to the PIN, and the branch to the ECRB. The branch to ECRB is small and lies radial to the radial sensory branch; then radial to ECRB is the PIN. As in the identification and assessment of the donor nerves, a nerve stimulator is used to evaluate the recipient nerves for any residual innervation to the clinically paralyzed muscles. Factors such as patient age, injury mechanism, time since the injury, and muscle response to stimulation guide the decision-making process. If some muscle activation remains, neurolysis or an end-to-side nerve transfer may be considered. However, when there is no muscle response, an end-to-end nerve transfer is typically performed. In this scenario, the branches to the ECRB and PIN are mobilized and divided proximally, usually at or above the elbow crease. The adage “donor distal, recipient proximal” should be considered when dividing nerves for transfer.
The donor nerves are then transferred and sutured to the recipient nerves using microsurgical techniques, often with 9-0 nylon in a epineural fashion, ensuring minimal tension at the repair site. The donor nerves are typically routed deep to the radial vessels to create a direct path for coaptation. Adhering to the principle of “donor distal, recipient proximal” helps achieve a tension-free repair and optimizes axonal regeneration.
The outcomes of this procedure are notable, with restoration of wrist extension achieved through the FCR-to-ECRB transfer and recovery of finger and thumb extension facilitated by the PT or FDS-to-PIN transfer. This nerve transfer significantly improves hand function and quality of life for patients with radial nerve palsy.
Advantages and Challenges
Nerve transfer techniques offer several advantages for restoring motor function. These approaches enable targeted restoration of specific movements, such as independent digit extension, by leveraging redundant motor branches. Nerve transfers preserve the biomechanical advantage of native muscle-tendon units and line of pull. Furthermore, this strategy minimizes donor site morbidity while maintaining functionality in the donor muscles. Additionally, the use of synergistic donor-recipient nerve pairs facilitates motor reeducation and accelerates recovery.
However, these procedures also present challenges. Scarring in the volar forearm, whether from previous trauma or prior surgeries, can complicate the identification of donor and recipient nerves, making it difficult to perform the transfer or achieve a tension-free coaptation. Nerve transfers are also time sensitive, and typically need to be performed within 6-10 months after injury. In some instances, performing nerve transfers run the risk of downgrading potential tendon transfer donors in the event that the nerve transfer is unsuccessful Even after a successful nerve transfer, motor recovery takes considerable time, often requiring 9-12 months before noticeable functional improvement is observed.
Postoperative Rehabilitation
Rehabilitation is a cornerstone of recovery after nerve transfer surgery. It typically begins with immobilization for 3-4 weeks to protect the nerve coaptations, followed by a regimen of passive and active range of motion exercises to prevent joint contractures. Patients must relearn how to activate the transferred nerve’s new function. Early mobilization under supervision and electrical stimulation may enhance outcomes. Neuromuscular reeducation, including electrical stimulation and targeted motor exercises, helps the brain relearn how to activate the transferred nerve.
Patient Outcomes After Nerve Transfers for Radial Nerve Palsy
Nerve transfers for radial nerve palsy generally yield favorable outcomes, particularly in restoring essential functions of the hand and wrist. One of the primary goals of these procedures is the restoration of wrist extension, a critical function for grip strength and overall hand utility. Most patients achieve satisfactory wrist extension postsurgery. Additionally, finger and thumb extension, which are vital for grasp and pinch functions, often improve significantly. While outcomes vary, many patients regain sufficient dexterity to manage daily tasks effectively. Muscle strength recovery depends on factors such as the extent of nerve damage, timing of the surgery, and the quality of nerve coaptation. While some patients achieve near-normal strength, others may experience mild to moderate weakness.
Recovery following nerve transfer surgery is a lengthy process. Nerve regeneration occurs at a rate of approximately 1 mm per day, and functional recovery can take 6-12 months or longer. Intensive rehabilitation during this period is essential to maximize outcomes, as it helps retrain the muscles and nerves for their new roles.
As with any surgical procedure, nerve transfers come with certain risks and limitations. Donor site morbidity, or functional loss at the donor site, is a potential complication, though careful donor nerve selection helps mitigate this risk. Incomplete recovery is another challenge, with some patients experiencing residual weakness or stiffness in wrist and finger extension. Additionally, surgical scarring and fibrosis may occasionally impair nerve regeneration, affecting the overall success of the procedure.
Clinical studies have underscored the effectiveness of nerve transfers. For instance, Ray and Mackinnon, in their study of 19 patients who underwent median-to-radial nerve transfers, reported that 18 patients achieved MRC grade 4+ wrist extension recovery after an average follow-up of 20 months. In terms of finger and thumb extension, 12 patients regained MRC grade 4 or better strength, 2 recovered to MRC grade 3, and 5 demonstrated MRC grades 0-2. To provide immediate wrist extension during the reinnervation process, 9 of these patients also underwent a pronator teres (PT) to extensor carpi radialis brevis (ECRB) tendon transfer. Separately, Ukrit et al. reported the feasibility of flexor digitorum superficialis (FDS) to ECRB nerve transfer, which showed promising results in anatomical studies and clinical applications. In 2 patients, both achieved MRC grade 4 wrist extension at 24 months postsurgery.
Overall, nerve transfers have proven to be a successful intervention for radial nerve palsy, with many patients achieving significant functional recovery in wrist and finger extension, underscoring their value in restoring hand functionality and quality of life.
Alternative Nerve Transfer Techniques
Pronator Quadratus to Extensor Carpi Radialis Brevis for Wrist Extension
Various alternative nerve transfer techniques have been explored in the treatment of nerve injuries. Bertelli et al. described a method where the motor branch of the pronator quadratus was transferred to the extensor carpi radialis brevis (ECRB) branch to restore wrist extension in 4 patients with brachial plexus injuries. One year after surgery, all patients achieved MRC grade 4 wrist extension. In another study, Bertelli and Ghizoni reported transferring the supinator motor branch to the posterior interosseous nerve (PIN) in 4 patients with C7-T1 brachial plexus palsy. By 12 months postoperatively, these patients regained MRC grade 3 extension at the metacarpophalangeal joints and thumb.
Pronator Teres to Extensor Carpi Radialis Longus for Wrist Extension
Garcia Lopez documented a case series involving 6 patients who underwent nerve transfer from a branch of the pronator teres (PT) to the extensor carpi radialis longus (ECRL) branch and from the flexor carpi radialis (FCR) branch to the PIN. These patients achieved M4 strength in the ECRL and extensor pollicis longus, with metacarpophalangeal extension rated at M4 in 4 cases and M3 in 2. However, grip strength in the operated limb reached only 93% of the unoperated side. Similarly, Rasulic et al. evaluated 4 patients with iatrogenic radial nerve injuries who underwent nerve transfers. All patients achieved satisfactory functional outcomes, with muscle strength rated at M3 or higher.
Supinator to Posterior Interosseous Nerve for Hand Opening
Transfer of the supinator motor branch to the PIN has been described as a useful transfer in both lower trunk brachial plexus injuries and tetraplegia. , , , The supinator retains its innervation from the C6 nerve root, making it a possible donor in both of these applications.
As it was originally described, a longitudinal incision is made over the proximal dorsal forearm. The interval between the ECRB and EDC is entered, and the proximal border of the supinator, otherwise known as the “arcade of froshe”, is identified. The supinator muscle is divided revealing the PIN and 2 branches to the supinator muscle. An anterior approach may also be employed to perform this transfer; in this approach, the radial nerve proper is identified between the brachialis and brachioradialis, and followed distally until the respective branches are encounted. In the setting of brachial plexus injury, a nerve stimulator is used to confirmed paralysis of the PIN, which would signal an indication to perform the nerve transfer. In the setting of tetraplegia, a nerve stimulator is used to confirm stimulation as an indication to perform the nerve transfer, as the goal in tetraplegia is to provide new volitional input to an otherwise functioning lower motor neuron, in this case the PIN. Nerves are divided again “donor distal, recipient proximal” and tension-free microsurgical coaptations are performed as previously described.
Bertelli and Ghizoni published a case series of 4 patients with C7-T1 brachial plexus palsies who subsequently regained hand opening. Bazarek et al. reported a series of twenty-three patients in which 83.3% and 94.4% hands and developed at least M3 thumb extension and finger extension respectively.
Nerve Transfers to Triceps for Elbow Extension
While not traditionally a priority for reconstruction in brachial plexus injury, some authors advocate for restoration of triceps to help position the hand in space and improve hand function, and stabilize the elbow. In isolated posterior cord injuries, the medial cord is available for potential nerve donors. Bertelli et al. described the use of selective use of a single branch to flexor carpi ulnaris (FCU) for the reinnervation of triceps. In this technique, a medial approach to the infraclavicular plexus is performed to identify the ulnar nerve which sits posterior to the brachial artery at this level. Through this same approach, the branch to the medial head of triceps can be identified and neurolysed to its take-off from the radial nerve at the level of the latissimus dorsal tendon. A separate incision at the cubital tunnel is performed to identify a branch to FCU, which is then divided distally and tunneled back to the proximal incision for coaptation. Using this transfer, Bertelli et al. reported 5 cases of brachial plexus injuries that recovered M4 elbow extension.
Alternatives to Nerve Transfers for Radial Nerve Palsy
When managing radial nerve palsy, various non-nerve transfer treatment options may be considered based on the timing, extent, and nature of the injury. These include nonsurgical methods, nerve grafting, tendon transfers, and direct nerve repair.
1. Nonsurgical Treatments
Nonsurgical approaches are typically the first line of treatment and focus on preserving function while awaiting potential nerve recovery.
Splinting and Orthotics are commonly used to prevent wrist drop and maintain hand functionality. Dynamic splints may support finger extension, improving the patient’s ability to perform functional tasks such as grasping and releasing objects. These devices also help avoid joint and muscle contractures during the recovery period.
A tailored physical therapy regimen is critical in the early stages of treatment. Therapy focuses on maintaining joint range of motion, preventing muscle atrophy, and enhancing strength in unaffected muscles. It also prepares patients for potential surgical interventions if recovery is incomplete.
Neuromuscular electrical stimulation (NMES) may aid in maintaining muscle tone and facilitating neural recovery by stimulating the paralyzed muscles. While some studies suggest NMES can be beneficial, its long-term efficacy remains a topic of ongoing research.
2. Direct Nerve Repair
In cases where the radial nerve injury is sharp and clean, direct end-to-end repair may be possible. The surgeon aligns and sutures the nerve ends without tension, promoting axonal regeneration. However, direct repair is often not feasible in injuries involving significant trauma, delayed presentation, or extensive nerve damage. When possible, this approach can result in favorable recovery, provided there is adequate soft tissue coverage and the repair is performed early. Often, nerve or tendon transfers may be considered in conjunction with direct nerve repair.
3. Nerve Grafting
For cases where the radial nerve injury involves a gap that prevents direct repair, nerve grafting may be employed. , As with direct nerve repair, nerve transfers or tendon transfers may be considered in conjunction. Autologous grafts are typically harvested from expendable sensory nerves, such as the sural nerve, to bridge the defect. The outcomes of nerve grafting depend on several variables, including the length of the graft, the patient’s age, and the duration between injury and surgery. Early intervention often yields better results, as prolonged denervation can reduce the potential for muscle reinnervation. Regardless, grafting of high radial nerve injuries has demonstrated unpredictable results and many advocate for combining grafting with nerve and or tendon transfers to improve long-term results. ,
4. Tendon Transfers
Tendon transfers represent a time-tested surgical solution for patients with long-standing radial nerve palsy or cases where nerve recovery is unlikely. This technique involves rerouting functioning muscles and their tendons to replace the lost function of paralyzed muscles, allowing restoration of critical hand movements. Many surgeons, including the senior author, prefer tendon transfers to nerve transfers for radial nerve palsy due to their predictability and more rapid functional recovery.
It is important to understand the principles of tendon transfers to achieve optimal patient outcome and are delineated here.
Patient Selection and Evaluation: The selection process begins with a thorough assessment of the patient’s functional deficits and the prioritization of reconstructive goals, such as restoring wrist extension and prehensile positions for grasp and pinch. Donor muscles should demonstrate sufficient strength (graded at least 4/5 on the Medical Research Council scale), and target joints must be mobile and stable, as fixed contractures or joint stiffness can compromise outcomes. Tendon transfers are typically performed after nerve recovery potential is deemed low, which is generally at least 6-12 months postinjury or in cases of permanent paralysis of muscles.
Donor Tendon Selection: The donor tendon must possess adequate strength to replace the lost function without significantly impairing its original role. Ideally, the donor tendon’s function should be synergistic with the desired motion to facilitate easier motor relearning postoperatively. For instance, wrist flexion synergizes with digital extension, making the flexor carpi radialis (FCR) a suitable donor muscle for transfer to the extensor digitorum communis (EDC). Additionally, the donor tendon must have sufficient excursion to achieve the desired movement; for example, the flexor digitorum superficialis (FDS) offers a greater excursion (6 cm) compared to FCR (3 cm).
Biomechanical Alignment: Successful tendon transfers require precise biomechanical alignment. The transferred tendon should follow a straight line of pull that mimics the natural axis of the replaced muscle-tendon unit, ensuring optimal force generation and efficiency. Proper tensioning is critical; the tendon should not be too tight or too loose, as this may impair movement or function.
Surgical Technique: A minimally invasive surgical approach is preferred to minimize tissue disruption, preserve blood supply, and prevent excessive scar formation, which can hinder tendon glide and excursion. Tendons should be securely sutured using techniques such as the Pulvertaft weave or side-to-side sutures to prevent slippage. It is essential to preserve vascularity to both the donor and recipient tendons during the procedure.
Functional Prioritization: Restoring critical functions essential for daily activities, such as grasp, pinch, and wrist stability, is prioritized before addressing secondary functions. While it is ideal to use a different donor tendon for each desired function, a single donor may be utilized to restore multiple functions if necessary. For example, the FCR can be used to restore MCP extension of the second through fifth digits.
Postoperative Rehabilitation: Rehabilitation begins with early controlled mobilization to prevent adhesions and maintain joint mobility. Motor reeducation is a vital component, as patients must learn to activate the transferred tendon in its new role. Synergistic transfers simplify this process. Gradual strengthening of the transferred tendon is emphasized, focusing on increasing strength and endurance over several weeks to months.
Realistic Expectations: Patients should be educated that tendon transfers aim to restore functional rather than anatomical movement. It is important to set realistic expectations regarding outcomes, including the likelihood of residual weakness in the donor muscle. Understanding these trade-offs is crucial for patient satisfaction and overall success.
Adhering to these principles maximizes the success of tendon transfer surgeries and ensures optimal functional outcomes for patients with upper extremity deficits. The most commonly performed tendon transfers for radial nerve palsy include ( Table 2 ):
- •
Pronator Teres (PT) to Extensor Carpi Radialis Brevis (ECRB): This transfer restores wrist extension and is a cornerstone of radial nerve palsy reconstruction.
- •
Palmaris Longus (PL) to Extensor Pollicis Longus (EPL): This transfer reestablishes thumb extension.
- •
Flexor Carpi Radialis (FCR) to Extensor Digitorum Communis (EDC): This restores finger extension and may also involve connecting FCR to the extensor indicis proprius (EIP) and extensor digiti quinti (EDQ).
Related posts:
Evaluation and Grading of Peripheral Nerve Injuries
Complete Brachial Plexus Injuries: Review of Surgical Techniques and Functional Outcomes
Nerve Transfers for Median Nerve Injury
Operative Techniques in Orthopedics: Ulnar Nerve Transfers
Nerve Transfers for Brachial Plexus and Upper Extremity Nerve Injuries
Upper Extremity Targeted Muscle Reinnervation
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