Nerve transfers in the hand are devised to restore hand function and critical sensation through reinnervation of the target muscles or sensory territories. The motor function of the hand can be organized into three categories: median, radial, and ulnar nerve function. The principle nerves that are targeted for reinnervation are the anterior interosseous nerve (median), posterior interosseous nerve (radial), and deep motor branch (ulnar). Motor nerve transfers are time sensitive due to muscle atrophy and loss of motor end-plates.

Restoration of hand sensation can be accomplished through nerve transfers by donating non-critical sensory territories to reinnervate critical sensory territories that include 1st webspace, ulnar cutaneous aspect of the hand, and the posterior radial aspect of the hand. These critical territories are restored through an end-to-end (ETE) nerve transfer. While there is lost of donor nerve, it can be preserved to a rudimentary level through an end-to-side (ETS) nerve transfer. Non-critical sensation can also be restored to a rudimentary level through the same ETS method. The combination of ETE and ETS nerve transfers allows for the best clinical outcome for sensory reinnervation. Unlike motor nerve transfers, sensory nerve transfers are not time sensitive.

Related Links

Hand Anatomy

Hand Physical Examinnation

Sensory Examination

Procedures – Restoration of Hand Function

Fingers and Thumb Flexion (Median Nerve)

Flexor Digitorum Superficialis to Anterior Interosseous Nerve Transfer

Title: Flexor Digitorum Superficialis to Anterior Interosseous Nerve Transfer.
Published: 4/27/2011, Updated: 4/27/2011.

Author(s): Susan E. Mackinnon MD, Andrew Yee BS.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

Figure 1 – Exposure and Identification of the Median Nerve and Donor Flexor Digitorum Superficial Nerve Branch and Recipient Anterior Interosseous Nerve. The median nerve was exposed by step-lengthening the superficial head of the pronator teres, releasing the deep head of the pronator teres, and releasing the arch of the proximal flexor digitorum superficialis. In this particular patient, there was a small tendonious attachment for the deep head of the pronator teres. The recipient anterior interosseous nerve was identified on the radial aspect of the median nerve. The nerve to the flexor digitorum superficial was identified to branch from the ulnar aspect of the median nerve

Figure 2 – Mobilization of the Flexor Digitorum Superficialis Nerve and Anterior Interosseous Nerve for Transfer. The donor flexor digitorum superficialis nerve was transected distally to transpose for the nerve transfer. The anterior interosseous nerve was transected proximally to transpose for the nerve transfer.

Figure 3 – Flexor Digitorum Superficialis to Anterior Interosseous Nerve Transfer. The flexor digitorum superficialis nerve branch was transferred to the anterior interosseous nerve to restore anterior interosseous nerve function. This nerve transfer was utilized for an isolated anterior interosseous nerve palsy.

Brachialis to Anterior Interosseous Nerve Transfer for Lower Plexus Injuries
Extensor Carpi Radialis Brevis to Anterior Interosseous Nerve Transfer

Title: Extensor Carpi Radialis Brevis to Anterior Interosseous Nerve Transfer.
Published: 4/11/2011, Updated: 4/11/2011.

Author(s): Susan E. Mackinnon MD, Andrew Yee BS.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

The senior author’s preferred nerve transfer to reinnervate anterior interosseous nerve (AIN) function is the brachialis to anterior interosseous nerve transfer. However, in cases with major brachial plexus injuries, the brachialis nerve will not be available as a donor nerve due to its C5,6 root origination. In these cases, the nerve to the extensor carpi radialis brevis (ECRB) is an excellent donor nerve substitute when available. The ECRB to AIN nerve transfer is an easier and quicker transfer when compared to the brachialis to AIN nerve transfer due to a few different technical points. These technical points include that the ECRB to AIN nerve transfer does not require interfascicular dissection and the nerve transfer is closer to the AIN motor targets than the brachialis transfer. The surgical exposure for the ECRB to the AIN nerve transfer occurs in the proximal-forearm, at the level of the median nerve, where the AIN branches and is easily identified lateral to the median nerve. In comparison, the brachialis to AIN nerve transfer occurs in the mid-arm and requires intrafascicular dissection of the median in order to mobilize the recipient AIN fascicle for transfer. In summary, for severe brachial plexus injuries, the ECRB nerve is an excellent donor nerve choice to reinnervate AIN function when the brachialis nerve is not available.

Figure 1 – Identification of Median Nerve Branches and the Recipient Anterior Interosseous Nerve. The median nerve is decompressed and exposed in the forearm by releasing the superficial head of the pronator teres and the tendonious arch of the flexor digitorum superficialis. The recipient anterior interosseous nerve is identified branching from the median nerve’s lateral aspect.

Figure 2 – Identification of Radial Nerve Branches and the Donor Extensor Carpi Radialis Brevis Nerve Branch. The radial nerve is exposed by retracting the brachioradialis muscle laterally. The donor extensor carpi radialis brevis nerve branch is identified branching from the radial nerve’s lateral aspect distal to the deep branch of the radial nerve and proximal to the superficial branch of the radial nerve.

Figure 3 – Isolating the Donor and Recipient Nerve. The donor extensor carpi radialis brevis nerve is isolated by transecting the nerve distally. The recipient anterior interosseous nerve is isolated by transecting the nerve proximally. The donor distal and recipient proximal transections will allow for a tension-free repair.

Figure 4 – Extensor Carpi Radialis Brevis to Anterior Interosseous Nerve Transfer. The extensor carpi radialis brevis is transferred to the anterior interosseous nerve for a tension-free repair. This transfer is used to reinnervate anterior interosseous nerve function, specifically flexor digitorum profundus III and IV, flexor pollicis longus, and pronator quadratus.

Surgical Techniques

PROCEDURE: Extensor Carpi Radialis Brevis to Anterior Interosseous Nerve Transfer.

Donor Nerve: Extensor carpi radialis brevis nerve branch of the radial nerve.

Recipient Nerve: Anterior interosseous nerve of the median nerve.

Nerve Coaptation: End-to-end.

Incision Description:

A lazy-S volar incision is made in the proximal-forearm, about 12cm in length.

Sugical Steps:

Exposure and Dissection:

1. Incise skin and dissect through subcutaneous tissue.

Median Nerve Decompression and Exposure:

2. In the distal portion of the incision, the radial vessels are identified and the radial sensory nerve is identified. The pronator teres tendon is located between these two structures.

3. A step-lengthening tenotomy of the pronator teres tendon is performed at this level.

4. Moving proximally in the forearm, the median nerve is identified just medial to the radial vessels.

5. The deep head of the pronator teres is divided to expose the median nerve.

Extensor Carpi Radialis Brevis to Anterior Interosseous Nerve Transfer:

6. The anterior interosseous nerve is identified as the major branch coming off of the median nerve on the radial side.

7. There is a cleavage plain between the anterior interosseous nerve and the median nerve that allows for the proximal neurolysis of the anterior interosseous nerve for additional length.

8. The anterior interosseous nerve is stimulated to confirm that it is not functioning.

9. The nerve to the extensor carpi radialis brevis (ECRB) is then identified by following the radial sensory nerve proximally and observing the nerve branch takeoff of the smaller nerve to the ECRB. This nerve is stimulated to confirm function.

10. The donor nerve, ECRB, is divided distally.

11. The ECRB nerve is transposed towards the anterior interosseous nerve (AIN).

12. The recipient nerve, AIN, is divided proximally.

13. The nerve repair is completed with no tension on the repair through full range of movement of the extremity.

Extensor Carpi Radialis Brevis to Pronator Teres and Supinator to Anterior Interosseous Nerve Transfer
Flexor Digitorum Superficialis to Flexor Pollicis Longus Nerve Transfer for Partial Median Nerve Injury

Fingers and Thumb Extension (Radial Nerve)

Median (FCR / FDS) to Radial (PIN / ECRB) Nerve Transfer

Title: Median (FCR / FDS) to Radial (PIN / ECRB) Nerve Transfer.
Published: 7/14/2011, Updated: 7/19/2011.

Author(s): Ida K. Fox MD, Andrew Yee BS, Susan E. Mackinnon MD.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

The median to radial nerve transfer was first performed in a unique radial nerve palsy patient.  This first patient had a proximal injury associated with a humeral head fracture and lost radial nerve function. In this case, tendon transfers were contraindicated due to coexisting complex regional pain syndrome and associated stiffness. In addition, nerve grafting was contraindicated due to proximal level of injury and advanced age. Excellent results following the median to radial nerve transfer in this single patient have allowed the expansion of indications such that nerve transfers are an alternative to tendon transfers and nerve grafting. The median to radial nerve transfer utilizes the following specific nerve branches for transfer: (1) flexor carpi radialis to the posterior interosseous nerve and (2) flexor digitorum superficialis to the extensor carpi radialis brevis. The median nerve branches are “pre-dissected” and no interfascicular dissection is required during this procedure. At our institution, we combine this with an end-to-side tendon transfer of pronator teres to extensor carpi radialis brevis as long as there is no significant stiffness for early recovery of wrist extension. Early motor re-education shortens the time of recovery, with reinnervation of radial nerve muscles usually noted by nine months.

Figure 1 – Orientation and incision for median to radial nerve transfer. A lazy-S incision is made over the proximal volar forearm, starting in the antecubital fossa and extending half of the distance to the wrist crease over the medial border of the brachioradialis. The incision has been lengthened distally to mobilize the pronator teres tendon for transfer to the extensor carpi radialis tendon. (A) Orientation image and dotted markings for an unused incision. (B) Actual incision is visualized.

Figure 2 – Exposure and identification of the lateral antebrachial cutaneous nerve (LABC). Upon exposure, the LABC is identified to accompany the cephalic or accessory cephalic vein. These structures are protected as dissection continues through the antebrachial fascia.

Figure 3 – Landmarks for identifying the tendon of the superficial head of the pronator teres. radial vessels, specifically the radial artery, are found between the brachioradialis and the pronator teres. By retracting the brachioradialis laterally, the superficial branch of the radial nerve is identified lateral to the radial vessels. Lateral to this nerve or beneath lies the tendon of the superficial head of the pronator teres.

Figure 4 – Identifying the tendon of the superficial head of the pronator teres to release for the pronator teres (PT) to extensor carpi radialis brevis (ECRB) tendon transfer. The pronator teres tendon is marked in purple to mobilize and release it from the radius for the PT to ECRB tendon transfer. However, if this tendon transfer is not performed unlike in his case, the pronator teres tendon is step-lengthened with a “Z-like” incision to allow for the proximal exposure of the median nerve for transfer.

Figure 5 – Release of the pronator teres tendon from the radius for the pronator teres (PT) to extensor carpi radialis brevis (ECRB) tendon transfer. The pronator teres tendon is released from its insertion attachment to the radius and mobilized for the PT to ECRB tendon transfer. If this tendon transfer is not performed unlike in this case, the pronator teres remains attached and its tendon is step-lengthened.

Figure 6 – Identifying extensor carpi radialis brevis (ECRB) inferior to extensor carpi radialis longus (ECRL). ECRB is located inferior to ECRL. Their function can be confirmed by pulling the respective tendon proximally and observing the actions of the hand. ECRL inserts at the dorsum of the first and second digits producing wrist extension with radial deviation, while ECRB inserts at the dorsum of the third digit producing specifically wrist extension.

Figure 7 – Identifying the recipient extensor carpi radialis brevis (ECRB) muscle for tendon transfer. The recipient ECRB for tendon transfer is located inferior to the extensor carpi radialis longus (ECRL). By retracting ECRL, the ECRB tendon is observed.

Figure 8 – Identifying the deep head of the pronator teres for the exposure of the median nerve. The deep head of the pronator teres is identified medial to the radial vessels and lateral to the superficial head. The deep head has a deep origin that superficial to the median nerve. The deep head of the pronator teres is divided to expose the median nerve.

Figure 9 – Release of the deep head of the pronator teres. By releasing the deep head of the pronator teres, the median nerve is identified. The respective donor nerves for the median to radial nerve transfer are located on medial aspect of the median nerve. The anterior interosseous nerve can be used as a landmark to gauge where the donor nerves branches from the median nerve.

Figure 10 – Identifying and releasing the tendious arch of the flexor digitorum superficialis (FDS). The next structure that is released to further expose the median nerve is the tendious arch of the FDS. The tendious arch is seen with a sharp border and is responsible in some patients for median nerve compression at this level.

Figure 11 – Exposure of the median nerve and its donor branches. Following the release of the tendious arch of the flexor digitorum superficialis (FDS), the median nerve and its donor branches are identified. The donor flexor carpi radialis (FCR) nerve branch is identified proximally with the palmaris longus nerve branch. Distally, two donor FDS nerve branches are identified. In most cases, there is an additional FDS nerve branch distal to these branches. This can be confirmed by electrical stimulating the medial aspect of the median nerve.

Figure 12 – Exposure of the radial nerve by dissecting through the tendinous fibers of the supinator. Moving to the lateral side of the radial vessels and retracting the brachioradialis, the superficial branch of the radial nerve is identified. Deep to this nerve are the recipients – posterior interosseous nerve (deep branch of the radial nerve) and the extensor carpi radialis brevis nerve branch. To expose these recipient nerves, requires dividing first the tendinous fibers of the extensor carpi radialis brevis and then the tendinous fibers of the superficial head of supinator.

Figure 13 – Exposure of the radial nerve and its recipient branches. Following the release of the tendious fibers of the extensor carpi radialis brevis (ECRB) and supinator, the radial nerve and its recipient branches are exposed. Lateral to the superficial branch of the radial nerve is the recipient nerve to the ECRB. The posterior interosseous nerve (PIN) is the second recipient nerve and is identified lateral to the ECRB nerve. A supinator nerve is seen to branch from the medial and deep aspect of the PIN. The supinator nerve is not included in the median to radial nerve transfer.

Figure 14 – Donor median nerve and recipient radial nerve and its branches. The donor median nerve branches, flexor carpi radialis (FCR) and flexor digitorum superficialis (FDS), are observed. In addition, the recipient radial nerve branches, posterior interosseous nerve (PIN), and extensor carpi radialis brevis (ECRB), are observed. The supinator nerve is not included in the nerve transfer.

Figure 15 – Dividing the recipient posterior interosseous nerve (PIN) to not include the supinator nerve. The PIN is divided proximally with the supinator branch. The supinator branch is then neurolyzed from the PIN as it is included in the reconstruction. The supinator, being already deinnervated, is not a critical function designated for reinnervation.

Figure 16 – Transecting the donor median and recipient radial nerves for nerve transfer. To acquire sufficient length for nerve transfer, the donor median nerves, flexor carpi radialis (FCR) and flexor digitorum superficialis (FDS), are transected distally and the recipient radial nerves, posterior interosseous nerve (PIN) and extensor carpi radialis brevis (ECRB), are transected proximally.

Figure 17 – Median to radial nerve transfer. The median to radial nerve transfer is composed of two transfers. (1) The donor flexor carpi radialis (FCR) nerve is transferred to the recipient posterior interosseous nerve (PIN). (2) The donor flexor digitorum superficialis (FDS) nerve is transferred to the recipient extensor carpi radialis brevis (ECRB) nerve.

Figure 18 – Weaving the donor pronator teres tendon into the recipient extensor carpi radialis brevis (ECRB) tendon. After identifying the ECRB tendon, a weaving forceps is used to pierce the ECRB tendon to grasp the pronator teres tendon. This first weave sets the tension for the tendon transfer.

Figure 19 – Pronator teres to extensor carpi radialis brevis (ECRB) tendon transfer. Following the first weave and the tension is set, the pronator teres and ECRB tendons are sutured several times together. Following, the ECRB tendon is woven several times distally into the pronator teres tendon and sutured together.

Hand Intrinsics (Ulnar Nerve)

Anterior Interosseous to Ulnar Motor Nerve Transfer
Reverse ETS Anterior Interosseous to Ulnar Motor Nerve Transfer

Title: Reverse End-to-side Anterior Interosseous to Ulnar Motor Nerve Transfer.
Published: 3/2/2011, Updated: 4/6/2011.

Author(s): Susan E. Mackinnon MD, Andrew Yee BS.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

The anterior interosseous to ulnar motor nerve transfer was first performed by Mackinnon SE in April of 1991 in a patient with a complete high ulnar nerve injury. Since then, the procedure has been used by our institution to recover some intrinsic function in patients with otherwise irreparable ulnar nerve injuries. However, there is a much larger population of patients with the varied ulnar intrinsic function: (1) patients with some, but not normal ulnar intrinsic function, (2) patients with good, but not certain likelihood of some intrinsic recovery with a more distal ulnar nerve repair, and (3) patients with high ulnar nerve injury, but have a martin-Gruber component to their ulnar intrinsic function. This larger population pool of patients, with indications that do not fall under the anterior interosseous to ulnar motor end-to-end nerve transfer, could utilize an augmentation of some ulnar nerve function with additional motor fibers. The anterior interosseous nerve (AIN) is also the donor nerve choice for augmentation of ulnar nerve intrinsic function. Rather than an end-to-end (ETE) nerve transfer with the AIN, a reverse end-to-side (RETS) nerve transfer is completed. That is, the end of the donor AIN is coaptated to the side of the recipient motor fascicular group of the ulnar nerve through an epineural window. This allows for the “supercharge” of the ulnar motor component. The RETS anterior interosseous to ulnar motor nerve transfer was first performed by our institution in August of 2009 and found, a year later, excellent recovery of ulnar nerve intrinsic function in a patient with recurrent cubital tunnel syndrome. The RETS procedure was performed after completing a rat experimental study, which definitively showed motor axons regenerating into a denervated nerve in a RETS fashion. This study was originally designed as a potential negative study, but surprisingly found equal transversing nerve fibers in the RETS coaptation when compared to an ETE coaptation. Since the experimental study, our institution has found many clinical situations where the RETS procedure has been an excellent addition to the surgical management of patients with ulnar intrinsic weakness.

Figure 1 – Guyon’s Canal Release with Deep Motor Branch. The Guyon’s canal is released to decompress the ulnar nerve prior to the reverse end-to-side anterior interosseous to ulnar motor nerve transfer. Additionally, the deep motor branch is decompressed by releasing the tendonous, leading edge of the hypothenar muscles. To help orient the surgeon, the hook of the hamate is used as an anatomical landmark. The Guyon’s canal release will prevent any possible compression points that are detrimental to nerve regeneration as the nerve regenerates distally. In addition, this release can help orient the surgeon on the intrafascicular anatomy of the ulnar nerve. Neither the ulnar nerve nor the superficial sensory branch is shown. However, they are ulnar to the ulnar artery.

Figure 2 – Identification of the Donor Anterior Interosseous Nerve. The anterior interosseous nerve is identified as the donor nerve by reflecting the flexor muscle bundle radially. The anterior interosseous vessels course parallel to the nerve as it innervates the pronator quadratus distally. The branches to the pronator quadratus are isolated for this nerve transfer. Be aware that any branches found distal to the pronator quadratus are sensory only and provide proprioception to the wrist joint.

Figure 3 – Identification of the Ulnar Nerve and Determining the Area of Neurolysis. The ulnar nerve is identified with the dorsal cutaneous branch of the ulnar nerve. Be aware of the anatomy as the dorsal cutaneous branch is ulnar to the ulnar nerve, and the ulnar artery is radial to the ulnar nerve. By isolating the anterior interosseous nerve, the surgeon can transpose this nerve to the ulnar nerve to determine the area of neurolysis.

Figure 4 – Intraneurolysis of the Ulnar Nerve and Identifying the Recipient Motor Component. Intraneurolysis of the ulnar nerve reveals the motor and sensory components of the ulnar nerve. The motor component courses distally and becomes the deep motor branch innervating the intrinsic muscles of the hand. This recipient motor component is identified between the dorsal cutaneous branch and the sensory component of the ulnar nerve, resulting in a sensory-motor-sensory topography. The dorsal cutaneous branch is ulnar to the ulnar nerve, though here is manipulated and appears reversed. The motor component is smaller compared to the sensory component and composes 40% of the ulnar nerve while the sensory composes the other 60%.

Figure 5 – Reverse End-to-side Anterior Interosseous to Ulnar Motor Nerve Transfer. The anterior interosseous nerve is transferred to the motor component of the ulnar nerve through a reverse end-to-side epineural window coaptation. As the nerve gradually regenerates from a proximal injury to its target muscles, the reverse end-to-side nerve transfer can help preserve the distal target muscles in the interim by providing a closer source of nerve fibers.

Sensation

Median to Radial Sensory Nerve Transfer
Median to Ulnar Sensory Nerve Transfer
Ulnar to Median Sensory Nerve Transfer
Ulnar Index of Median to Ulnar Ring of Ulnar Sensory Nerve Transfer for Distal Injury

Title: Ulnar Index of Median to Ulnar Ring of Ulnar Sensory Nerve Transfer for Distal Injury
Published: 8/19/2011, Updated: 8/19/2011.

Author(s): 
Ida K. Fox MD, Andrew Yee BS.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

The median to ulnar sensory nerve transfer in the hand is a unique procedure to restore critical sensation to the ulnar border of the hand. In this case, a blast injury to ulnar aspect of the hand resulted in the discontinuity of the ulnar nerve sensory component, soft tissue coverage issues, and subsequent amputation of the small finger. The goals for this case were to restore critical sensation and prevent painful neuroma formation. Nerve grafting was contraindicated due to the extensive zone of injury and suboptimal tissue coverage over the putative site of graft placement. Therefore, a combination of distal sensory nerve transfer, proximal prevention of neuroma, and creative ‘spare parts’ surgery was used to treat this patient. The specific nerve branches transferred to restore sensation to the new ulnar border of the hand was the following: (donor) ulnar aspect of the index finger digital branch of median nerve to (recipient) ulnar aspect of the ring finger digital branch of ulnar nerve. Autologous nerve graft material was used to bridge the gap. In this case, the proximal sensory component of the ulnar nerve was a ‘spare part’ and used as the graft material. To prevent painful proximal neuroma, the proximal end of the sensory component of the ulnar nerve was extended using an acellularized nerve allograft (ANA). The distal end of the ANA was buried in the flexor carpi ulnaris muscle mass. To restore rudimentary sensation to the donor nerve territory (ulnar aspect of index finger), an end-to-side transfer of the ulnar aspect of the index finger digital branch to the radial aspect of the long finger digital branch sensory nerve transfer was performed. This procedure avoided long nerve grafting through the zone of injury at the palm, effectively restore sensation in the critical areas, and prevent proximal painful neuroma of the proximal ulnar nerve stump.

Figure 1 – Case presentation of a gunshot wound to the hand. A 5 year-old female presented to our institution with a gunshot wound to the ulnar aspect of the hand. Initial exploration and small finger amputation were completed. The sensory component of the ulnar nerve was injured with segmental loss and need for soft tissue coverage.

Figure 2 – Illustration of gunshot wound and nerve injury within the hand. The gunshot wound occurred at the ulnar palmar aspect of the hand which transected the ulnar sensory nerve branches distal to its branch point from the deep motor branch of the ulnar nerve.

Figure 3 – Surgical management and reconstruction of ulnar nerve sensation. The small finger required amputation. Due to the blast injury, there was poor soft tissue coverage at the palm preventing long nerve grafts. (1) Due to the distal injury, the median sensory nerve branch to the ulnar aspect of the index finger was selected as the donor nerve to transfer into the ulnar sensory nerve branch to the ulnar aspect of the ring finger for restoration of critical sensation. (2) Due to the required length needed, the ulnar nerve sensory component in the forearm was harvested proximally to bridge the gap as an autologous expendable nerve graft. (3) An acelluarized nerve allograft was used as an extender to allow proximal transposition of the ulnar nerve sensory component intramuscularly to prevent painful neuroma formation. (4) To restore rudimentary sensation back to the donor nerve sensory territory, an end-to-side nerve transfer to the median sensory branch to the radial aspect of the long finger was performed.

Figure 4 – Identification of the recipient digital nerve branch for nerve transfer. On the initial debridement, the transected digital nerve to the ulnar nerve to the ulnar aspect of the ring finger was identified and tagged with a suture. The adjacent common palmar digital artery was noted.

Figure 5 – Identification of the donor digital nerve branch for nerve transfer. An incision was made on the palmar aspect of the hand between the index and long finger. The digital nerve to the ulnar aspect of the index finger was identified as the donor nerve. This digital nerve was chosen as the donor for two reasons. The first is that the sensation to the ulnar aspect of the index finger is relatively expendable. The second is that the index finger was the furthest from the site of blast injury and was grossly intact. The adjacent digital nerve to the radial aspect of the long finger was also noted.

Figure 6 – Exposure of the ulnar nerve proximally in the forearm to harvest the nerve graft and to prevent neuroma formation. An incision was made proximally in the forearm to expose the ulnar nerve in order to harvest the sensory component of the ulnar nerve as a nerve graft. The dorsal cutaneous branch of the ulnar nerve was noted as well as the motor and sensory components of the ulnar nerve following initial intrafascicular neurolysis.

Figure 7 – Identification of the sensory component of the ulnar nerve as the nerve graft and prevention of neuroma formation. Upon further exposure and intrafascicular neurolysis, the sensory component of the ulnar nerve was identified on the radial aspect of the ulnar nerve. A microvessel is seen to separate the sensory from the motor component of the ulnar nerve.

Figure 8 – Harvesting the sensory component of the ulnar nerve as the nerve graft. (A) The sensory component of the ulnar nerve was harvested as the nerve graft. (B) A 3.5cm nerve graft was harvested from the ulnar nerve. The motor component of the ulnar nerve was protected and kept intact.

Figure 9 – Donor nerve and interposition nerve graft for nerve transfer and end-to-side nerve transfer to restore rudimentary sensation to the donor nerve territory. An interposition nerve graft from the sensory component of the ulnar nerve was coapted to the proximal end of the donor digital palmar branch of the median nerve to the ulnar aspect of the index finger. To restore rudimentary sensation to the donor nerve territory, the distal end of the ulnar index finger branch of median was end-to-side transferred and coapted to the side of the radial middle branch of median. Please note that this is a very unique case where the ulnar nerve sensory component is being used as expendable graft material. This is due to the small finger being amputated as part of the initial injury. The objective was to reinnervate the ulnar aspect of the ring finger by distal nerve transfers.

Figure 10 – Recipient nerve and interposition nerve graft for nerve transfer. The interposition nerve graft from the sensory component of the ulnar nerve was coapted to the distal end of the digital palmar branch of the ulnar nerve to the ulnar aspect of the ring finger. The nerve graft allows bridging the gap and reinnervating critical ulnar nerve sensation via nerve transfer. An autologous nerve graft was used to maximize reinnervation to this area of critical sensation.

Figure 11 – Acellularized nerve allograft as an extender from the sensory component of the ulnar nerve for intermuscular transposition. (A) A 5.5cm acellularized nerve allograft (Advance Nerve Graft, Axogen) was used. (B) The acellularized nerve allograft was coaptated to the proximal end of the sensory component of the ulnar nerve, transposed proximally, and buried deep within the forearm musculature to prevent painful neuroma formation.

Figure 12 – Intermuscular proximal transposition of the sensory component of the ulnar nerve using an acellularized nerve allograft extender. The sensory component of the ulnar nerve was extended using an acellularized nerve allograft (Avance Nerve Graft, Axogen) in order to proximally transpose into the flexor carpi ulnaris muscle and to bury the proximal stump to prevent painful neuroma.