Transferring the Motor Branch of the Opponens Pollicis to the Terminal Division of the Deep Branch of the Ulnar Nerve for Pinch Reconstruction

From surgical problem to surgical solution - lessons and reflections

In this insightful and personal biographical article, Professor Bertelli recounts his journey from surgical problem to surgical solution with incredible detail. This was an invited article as part of the 2025 FESSH/JHSE Special Issue on 'Technology and Innovation'. He shares some of this thought process behind novel nerve transfer or examination techniques, built on solid anatomical foundations and careful patient observations. Professor Bertelli attributes his achievements to the influence of mentors, the importance of cadaveric dissections and long years of clinical experience.

Histological study of donor/recipient feasibility in distal nerve transfer for the upper limb nerve injury

This study aimed to histologically investigate whether the compatibility of donor and recipient nerves in distal nerve transfer for radial and ulnar nerve palsy is suitable for restoring nerve function. Partial median to radial nerve transfer for radial nerve palsy and partial median to ulnar nerve transfer for ulnar nerve palsy were performed in 10 cadaveric upper limbs fixed using the Thiel technique. Histological analysis of the nerve samples at the coaptation site focused on the number of myelinated axons. Each recipient and donor nerve was identified in all specimens without any anatomical variations. While median-radial nerve transfer techniques showed an adequate number of donor axons, median-ulnar nerve transfer techniques showed a shortage of donor axons. The insufficiency of donor axons compared to the recipient axons may explain the challenges in reinnervating the recipient muscles. Combining the two different nerve transfers may compensate for the shortage of donor axons and improve motor recovery. Type of study and Level of evidence: Therapeutic, Level III.

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.

Nerve transfer of the median flexor pollicis brevis branch to the deep branch of the ulnar nerve for ulnar nerve palsy: a cadaveric feasibility study

An ulnar nerve (UN) palsy is devastating for hand function, resulting in an intrinsic minus position or claw hand with a loss of pinch grip. Distal nerve transfers facilitate faster reinnervation of hand intrinsic muscles in cases of proximal ulnar nerve lesions. The traditional anterior interosseous nerve (AIN) to UN motor transfer is commonly used, however, this still leads to long reinnervation times for the distal intrinsic muscles, important for the thumb to index pinch grip. This study investigated the feasibility of a more distal nerve transfer, from the median thenar to the deep branch of the UN (DBUN), in six cadaveric hands. A separate branch of the median nerve to the superficial head of flexor pollicis brevis (sFPB) arose distally of the thenar branch from the common digital nerve of the thumb shortly before the bifurcation of the ulnar palmar digital nerve to the thumb in all specimens, with a mean distance to the thenar branch of 8.3 ± 5.3 mm. The sFPB motor branch had a mean length of 11.5 ± 1.5 mm. The mean distance between the division of the dorsal cutaneous branch of the UN, where the AIN to UN motor transfer is usually performed, and the transfer between the sFPB branch to the DBUN was 132 ± 11 mm. A distal nerve transfer between the median innervated motor branch to the sFPB to the DBUN shortens the reinnervation distance for the first dorsal interosseous, the adductor pollicis, and the deep head of the FPB muscles, which is a prerequisite for restoration of the pinch grip.

Motor nerve transfers for reconstruction of traumatic upper extremity nerve injuries - a scoping review

Peripheral nerve injuries to the radial, median, and ulnar nerves have been traditionally treated via direct repair or interposition nerve grafts. Late presentation or failed functional restoration may be salvaged with tendons transfers. Nerve transfers may be deployed either as an adjunct to a proximal reconstruction or as a primary reconstructive strategy, and these techniques are being increasingly adopted as the published evidence matures. The advantages of nerve transfers include shorter reinnervation distances, restoration of original muscle action, and maintenance of independent muscle function. Tendon transfers are reliable, not dependent on time, and the functional use of the limb is often achieved quickly,. Hybrid combinations that combine nerve and tendon transfers can also be used to maximize the recovery potential. This scoping review aimed to provide an overview of nerve transfer possibilities after peripheral nerve injuries and guide management decisions for clinicians treating patients with upper limb paralysis from peripheral nerve injuries.

Anatomical Characterization of the Motor Branch to the Fourth Lumbrical: A Cadaver Study

PURPOSE

The branching pattern of the deep motor branch of the ulnar nerve (DBUN) in the hand is complex. The anatomy of the motor branch innervating the fourth lumbrical (4L), where paralysis results in a claw hand deformity after ulnar nerve injury, is not well defined. This cadaver study focused on mapping and defining anatomical landmarks in relation to the motor branch to the 4L.

METHODS

Ten fresh-frozen cadaver hands were dissected. The DBUN was exposed and followed distally, identifying all motor branches, until the branch to the 4L was seen. The small finger flexor tendons were reflected distally to enable visualization of the entire 4L motor branch and its distal entry point. The origin of the 4L motor branch was mapped in relation to fixed anatomical landmarks in the hand.

RESULTS

A consistent motor branch to the 4L and third palmar interosseous (3PI) muscles was seen originating from the DBUN in all specimens. The mean number of motor branches innervating the hypothenar muscles proximal to the 4L/3PI motor branch was 2.1 (range 1 to 5). The mean distance from the origin of the DBUN to the 4L/3PI motor branch was 2.9 cm (range 2.5 to 4.2 cm). The mean length of the 4L/3PI branch was 3.1 cm (range 2.3 to 4.5 cm). In seven specimens, the 4L/3PI branch demonstrated an intramuscular course through the 3PI before terminating in the 4L. In three specimens the 4L/ 3PI branch ran on the volar surface of the 3PI before terminating in the 4L.

CONCLUSIONS

A consistent 4L/3PI motor branch was mapped and characterized in all specimens.

CLINICAL RELEVANCE

These findings provide a guide for intraoperative localization of the 4L/3PI motor branch and also may provide further evidence to explain findings seen after distal nerve transfers to treat ulnar nerve injury.

The Super-Turbocharged End-to-Side Abductor Digiti Minimi and Anterior Interosseous Double Nerve Transfer Is Associated With Improved Ulnar Intrinsic Function

BACKGROUND

Nerve transfers to reinnervate ulnar intrinsic musculature can restore function in severe ulnar neuropathy, and supercharged end-to-side (SETS) nerve transfers have garnered early adoption. Given the relative expendability of the abductor digiti minimi (ADM), redirecting its axons to more critical components of the ulnar motor nerve (UMN) in a turbocharged end-to-side (TETS) nerve transfer with concomitant anterior interosseous SETS nerve transfer (AIN) as a super-turbocharged end-to-side (STETS) or twin-charged double nerve transfer may improve functional recovery.

METHODS

A retrospective study of patients undergoing the STETS AIN/ADM to UMN double nerve transfer or TETS ADM to UMN nerve transfer for severe ulnar neuropathy between 2020 and 2022 was performed. Primary outcomes were improvement in first dorsal interosseous (FDI) strength and Disabilities of the Arm, Shoulder, and Hand (DASH) scores. Dichotomous and continuous variables were compared with χ2 and t tests, respectively.

RESULTS

Fifty patients with severe ulnar nerve injuries were identified with at least 1-year surgical follow-up. Preoperative symptom duration was an average of 11.3 months. The STETS cohort (n = 42) reported significantly decreased DASH scores from 58 to 28 (P < .001) and improved FDI Medical Research Council (MRC) score from 0.7 to 3.3 (P < .001). The TETS cohort (n = 8) reported significantly decreased DASH scores from 54 to 23 (P = .016) and improved FDI MRC score from 2.0 to 3.6 (P = .008).

CONCLUSIONS

Distal transfer of the ADM nerve to the ulnar deep motor branch in a turbocharged fashion is reported. The findings suggest that the STETS double nerve transfer may improve patient outcomes and warrants further investigation with prospective cohort studies.

Review of Outcomes After Peripheral Nerve Transfers for Motor Nerve Injury in the Upper Extremity

BACKGROUND

Modern nerve-to-nerve transfers are a significant advancement in peripheral nerve surgery. Nerve transfers involve transferring donor nerves or branches to recipient nerves close to the motor end unit, leading to earlier reinnervation and preservation of the musculotendinous units in proximal nerve injuries. After nerve reinnervation, function may be superior to traditional tendon transfer techniques in terms of strength and independent motion. Nerve transfer surgery has emerged as a promising treatment option for many cases of nerve injury that were previously expected to result in poor outcomes, such as proximal injuries, long nerve gaps, or unavailability of the proximal injured segment.

METHODS

A review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Publications that focused on upper extremity nerve transfers were included, and functional motor and sensory recovery was analyzed. Technique reports, case reports, brachial plexus injuries, and reports on multiple nerve injuries were excluded.

RESULTS

A total of 48 relevant articles were identified with search criteria, and we discuss functional outcomes on nerve transfers for ulnar nerve injury, musculocutaneous nerve injury, median nerve injury, and radial nerve injury that met inclusion criteria.

CONCLUSIONS

Nerve transfers are an option for restoring hand and forearm function in patients with peripheral nerve injuries adversely affecting their ability to function. The literature demonstrates positive functional outcomes after nerve transfer operations, and thus, the utility and variations have increased. We aim to provide an overview of the outcomes of current nerve transfer techniques for ulnar, radial, median, and musculocutaneous acquired/traumatic mononeuropathies in the hand and upper extremity.

Management of "Long" Nerve Gaps

Long-gap nerve injuries offer unique physiological and logistical treatment challenges to the reconstructive surgeon. Options include nerve autograft, processed nerve allograft, nerve transfers, and tendon transfers. This review provides an evidence-framed discussion regarding the pros and cons of these diverse approaches.

Reconstructing Pinch Strength after Ulnar Nerve Injury by Transferring the Opponens Pollicis Motor Branch

BACKGROUND

With ulnar nerve injuries, paralysis of the first dorsal interosseous and adductor pollicis muscle weakens the patient's pinch. In the palm, we transferred the opponens pollicis motor branch to the deep terminal division of the ulnar nerve for pinch reconstruction.

METHODS

Sixteen patients with ulnar nerve injuries around the elbow underwent reconstruction and were followed up postoperatively for a minimum of 14 months. Their mean age was 41 ± 16 years, and the mean interval between injury and surgery was 134 ± 126 days (range, 2 to 390 days). Preoperatively and postoperatively, grasp, key, and subterminal key pinch strength were measured using dynamometers.

RESULTS

Reinnervation of the first dorsal interosseous muscle was observed in 15 of the 16 patients. Mean grasp strength improved from 15.5 ± 8.5 kg preoperatively to 24 ± 10 kg postoperatively, achieving 57% ± 16% of contralateral hand strength. Preoperatively, terminal key pinch averaged 3 ± 1 kg, which improved postoperatively to 5.5 ± 2 kg, achieving 71 ± 24% of the strength measured contralaterally. Preoperatively to postoperatively, subterminal key pinch force increased from 0 to 2.4 ± 1.3 kg, achieving 61% ± 27% that of the unaffected side. Patients who underwent surgery within 6 months of their injury showed a mean subterminal key pinch strength recovery of 63% ± 27% of the normal side, whereas those who underwent surgery between 7 and 13 months after injury showed a mean subterminal key pinch strength recovery of 51% ± 29%.

CONCLUSION

Transferring the opponens pollicis motor branch to the deep terminal division of the ulnar nerve improved pinch and grasp strength without jeopardizing thumb function.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Evaluating Outcomes Following Nerve Repair: Beyond the Medical Research Council

Peripheral nerve injuries are common and remain a significant health challenge. Outcome measurements are used to evaluate injury, monitor recovery after nerve repair, and compare scientific advances. Clinical judgement is required to determine which available tools are most applicable, which requires a vast understanding of the available outcome measurements. In this article we discuss the highest yield tools available for clinical application.

Distal nerve transfers for peripheral nerve injuries: indications and outcomes

Distal nerve transfer is a refined surgical technique involving the redirection of healthy sacrificable nerves from one part of the body to reinstate function in another area afflicted by paralysis or injury. This approach is particularly valuable when the original nerves are extensively damaged and standard repair methods, such as direct suturing or grafting, may be insufficient. As the nerve coaptation is close to the recipient muscles or skin, distal nerve transfers reduce the time to reinnervation. The harvesting of nerves for transfer should usually result in minimal or no donor morbidity, as any anticipated loss of function is compensated for by adjacent muscles or overlapping cutaneous territory. Recent years have witnessed notable progress in nerve transfer procedures, markedly enhancing the outcomes of upper limb reconstruction for conditions encompassing peripheral nerve, brachial plexus and spinal cord injuries.

Timing of surgery in peripheral nerve injury of the upper extremity

Peripheral nerve injuries present a complex clinical challenge, requiring a nuanced approach in surgical management. The consequences of injury vary, with sometimes severe disability, and a risk of lifelong pain for the individual. For late management, the choice of surgical techniques available range from neurolysis and nerve grafting to tendon and nerve transfers. The choice of technique utilized demands an in-depth understanding of the anatomy, patient demographics and the time elapsed since injury for optimized outcomes. This paper focuses on injuries to the radial, median and ulnar nerves, outlining the authors' approach to these injuries.Level of evidence: IV.

Base of the Third Metacarpal as a Palpable and Reliable Landmark for Identifying the Median Nerve's Thenar Branch

PURPOSE

The objective of this study was to investigate whether the base of the third metacarpal can predict the location of the thenar branch (TB) of the median nerve and the accuracy of palpating the base of the third metacarpal.

METHODS

In 15 patients with ulnar nerve lesions around the elbow, we transferred the opponens motor branch to repair the deep terminal division of the ulnar nerve (DTDUN). Before surgery, we located the TB by palpating the base of the third metacarpal volarly. During surgery, we placed three needles at the following places: one at the entrance of the TB into the abductor pollicis brevis, another at the point where the TB contacted the thenar muscles, and third at the DTDUN's trajectory over the third metacarpal. We obtained fluoroscopic images and measured distances between the needles and structures with image software. We also examined the relationship between the TB, DTDUN, and the volar tubercle of the base of the third metacarpal in cadaver hands. Finally, we invited 22 surgeons to palpate the base of the third metacarpal on volunteer hands and verified their accuracy using fluoroscopy.

RESULTS

During surgery, after dissection and palpation of the TB, under fluoroscopy, we confirmed that the palpable bone prominence was the base of the third metacarpal. In cadaver dissections, we observed the TB crossing the volar tubercle of the base of the third metacarpal superficially from proximal to distal and from ulnar to radial. The DTDUN was, on average, 14 mm distal to the base of the third metacarpal distal limit. In total, 19 of the 22 surgeons correctly identified the base of the third metacarpal and consequently the trajectory of the TB.

CONCLUSIONS

The palpable base of the third metacarpal can be used to determine the trajectory of both the TB and DTDUN.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Ulnar Nerve Injury during Treatment of Fourth and Fifth Metacarpal Fractures: A Case Report and Anatomical Review

The deep branch of the ulnar nerve (DBUN) is a pure motor nerve. It passes through a hypothenar fibromuscular tunnel and courses radially on the interossei surface. The DBUN is not frequently considered during hand fracture surgery, despite the anatomical course of the nerve in close relation to the carpal and metacarpal bones, which makes it vulnerable to penetrating injury and being injured during hand surgery fixations. In this article, we describe a case of DBUN injury after percutaneous pinning of the fourth and fifth metacarpal bone fractures complicated by intrinsic muscle wasting of the hand that was treated with neuroma excision and sural nerve graft. We present the case of a 36-year-old man, who had a fracture of the base of the fourth and fifth metacarpal bones, which was treated with multiple K-wires. A few months later, the patient presented with weak abduction/adduction of the three ulnar fingers and prominent wasting in the intrinsic muscles of the hand. On hand exploration, a 2-cm neuroma was found along the course of the DBUN distal to the hypothenar fibromuscular tunnel, which was treated by neuroma excision and nerve grafting. Fractures of the fourth and fifth metacarpals and carpometacarpal dislocations are very common and are often treated surgically. To fix these fractures, awareness of the DBUN course in the hand and its proximity to the carpal and metacarpal bones is important. High caution should be taken during percutaneous pinning by inserting K-wires under radiological guidance, minimizing pining attempts and limiting pin tip protrusion to 1-2 mm.

Distal Nerve Transfers in Hand and Forearm for Traumatic Brachial Plexus and Peripheral Nerve Injuries: A Narrative Review

Background

Various studies published good outcomes in brachial plexus injuries using nerve transfers for shoulder and elbow functions. However, little is known about the outcome of the distal nerve transfers in the forearm and hand. Targeting the nerve distally produces an early return of function in brachial plexus and peripheral nerve injuries (BPPNI). Therefore, researchers have focused on nerve transfers from the motor branches of the ulnar, median, and radial nerve. Similarly, sensory reinnervation is also obtained by potential donor transfers in the forearm and hand. There have been various attempts by surgeons to target the muscle and promote early reinnervation by different nerve transfers.

Conclusions

The distal nerve transfers in the forearm and hand are promising when performed early. It effectively restores hand and forearm functions and may be considered a better option than tendon transfer, which has a one-tendon-one function. This narrative review article discusses the different distal nerve transfers for various presentations of BPNNI.

Tendon Transfer versus Nerve Transfer for the Reconstruction of Key Pinch and Grip Strength in Isolated High Traumatic Injuries of the Ulnar Nerve: A Systematic Review

Background: Primary repair for traumatic injuries to the ulnar nerve alone does not always restore satisfactory hand function, particularly in injuries above the elbow where the long distances for regeneration limit motor reinnervation. Reductions in key pinch and grip strength are some of the main complaints. Tendon transfers have traditionally been used to improve key pinch and grip strength as a late salvage where primary nerve regeneration has run its course. Nerve transfers have been proposed as an alternative procedure and may be offered early to augment recovery, lengthen the window for reinnervation or provide motor reinnervation where the results of nerve repair are expected to be poor. This review sought to identify whether one type of procedure was superior to the other for reconstructing key pinch and grip strength. Methods: Medline, Embase and Cochrane Library were searched to identify articles that concerned nerve or tendon transfer following isolated traumatic injury to the ulnar nerve. Articles were excluded if patients had polytrauma or degenerative diseases of the peripheral nerves. Results: A total of 179 articles were screened for inclusion. And 35 full-text articles were read and assessed for eligibility, of which seven articles were eligible. Following citation search, two additional articles were included. Five tendon transfer articles and four nerve transfer articles were included. Key pinch and grip strength outcomes for both procedures were roughly similar, though tendon transfers carried a much higher risk of complications. Conclusions: Based on the key pinch and grip strength outcomes, tendon transfer and nerve transfer restore a similar degree of function following traumatic ulnar injury. Reported nerve transfer outcomes for grip strength were slightly better. Return to useful function was faster following tendon transfers. Preoperative data and more patient-reported outcome measures should be recorded in future studies to provide more context for each procedure type. Level of Evidence: Level III (Therapeutic).

Bilateral Ulnar Nerve Injury in the Wrist: Comparison of First Webspace Muscle Reconstruction by Opponens Nerve Transfer in the Right Hand Versus Direct Ulnar Nerve Repair in the Left Hand

We report a case of a bilateral glass injury to the wrist with transection of flexor tendons and the ulnar nerve and artery in a 60-year-old male patient. Two days after his accident, we repaired all divided structures, and on the right hand, we added the transfer of the opponens motor branch to the deep terminal division of the ulnar nerve aimed at first dorsal interosseous and adductor pollicis muscle reinnervation. After surgery, the patient was followed over 24 months. Postoperative dynamometry of the hand, which included grasping, key-pinch, subterminal-key-pinch, pinch-to-zoom, and first dorsal interosseous muscle strength, indicated recovery only in the nerve transfer side.

Innervation of the lumbrical and interosseous muscles in hand: analysis of distribution of nerve fascicles and quantification of their surface projections

We aimed to determine the surface locations of the nerve fascicles that innervate the lumbricals and interossei, re-examine the branching pattern of the deep branch of the ulnar nerve (dUN), and provide a clear description of their course. Eleven fresh-frozen adult cadaver hands were investigated. Nerve fascicles that innervate the lumbricals, interossei, and surface landmarks including the distal wrist crease and 2-5 proximal finger creases were marked by radio opaque fibers and subjected to X-ray. We analyzed the images and set a quadrant-linked hand surface. Subsequently, we measured the lengths of both axes and the coordinates of the branch locations in the quadrant. The surface locations of branches that innervated the lumbricals and interossei were clearly quantified. The branches of dUN exhibited a 4-group distribution pattern. Novel methods for quantitatively locating the surface anatomy of these branches and demonstration of a 4-group branching pattern of the dUN were established.

Reconstruction for bone tumours of the shoulder and humerus in children and adolescents

Reconstructions for paediatric bone tumours of the shoulder girdle and humerus are intended to optimize placement of the hand in space. Given the longevity of paediatric survivors of sarcoma, durability is an important planning consideration. Here, I review a subset of approaches based on anatomical site with an emphasis on function and longevity. Often, biological reconstructions that combine living bone with tendon repairs and transfers best address those goals.

Restoration of the first dorsal interosseous muscle

Motor dysfunction of the 1^st dorsal interosseous (DIO) muscle is typically observed in low and high ulnar nerve palsy. This causes weak thumb-index pinch, which can be disabling for the patient. Various reconstructive techniques have been described; however, the choice often depends on the surgeon's experience, the presence of associated neurovascular and musculotendinous injuries, as well as the requirements of the palliative surgery schedule. Nerve transfers can be proposed when patients present early in the course of the disease. Tendon transfers are often a last resort when late presentation occurs. Tendon transfers must follow general principles: the insertion is made on the 1^st DIO terminal tendon; the tension must be adjusted in a neutral position to avoid excessive tension, and immobilization is maintained for 4 weeks. Although many transfers are possible, the extensor pollicis brevis transfer is our preferred option. This donor does not require additional tendon grafting, has a direct line of pull close to that of the 1^st DIO and is not often used for other reconstructive purposes.

Effectiveness of Distal Nerve Transfers for Claw Correction With Proximal Ulnar Nerve Lesions

PURPOSE

To evaluate claw deformity correction following anterior interosseous nerve (AIN) end-to-end transfer to the deep motor branch of the ulnar nerve (DMBUN) in high ulnar nerve injuries.

METHODS

Eleven patients were retrospectively evaluated for metacarpophalangeal joint hyperextension and proximal interphalangeal joint extension lag in the fourth and fifth digits following ulnar nerve injury adjacent or proximal to the elbow, who underwent AIN end-to-end transfer to the DMBUN.

RESULTS

Patients underwent surgery an average of 5 months following injury (range, 2-9 months) and were followed for an average of 19 months after surgery (range, 12-30 months). At the last follow-up, clawing was observed in all patients, with proximal interphalangeal joint extension lag averaging 46.8° (SD, ±20°) in the fourth digit and 57.7° (SD, ±12°) in the little finger.

CONCLUSIONS

None of our patients experienced claw correction after AIN end-to-end transfer to the DMBUN.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

A novel nerve transfer: The first palmar interosseous motor branch of the ulnar nerve to the recurrent motor branch of the median nerve

INTRODUCTION

The recovery of recurrent motor branch of the median nerve might be delayed in high level median nerve injuries due to the long reinnervation distance. The aim of this study is to define a novel nerve transfer to restore the opposition and pinch.

METHODS

Two fresh frozen hand cadavers were used for the study. The motor branch of the first palmar interosseous muscle of the ulnar nerve was identified and dissected. Thenar branch of the median nerve was dissected from its insertion site. The motor branch of the first palmar interosseous muscle of the ulnar nerve was transferred to the thenar motor branch of the median nerve. Axon counts were examined histopathologically. Clinically this nerve transfer was performed for two female patients with a high-level median nerve injury. Mehta opposition scores were 21 and 20, respectively and the results were satisfactory six months after the surgery.

DISCUSSION

Although exploration and repair are recommended as the first treatment for median nerve injuries, the waiting time until the motor branch is reinnervated is critical in high level lesions. Nerve transfers become very important for fast recovery.

CONCLUSIONS

This new nerve transfer proposal may be an important step in nerve transfer surgery.

Severe Cubital Tunnel Syndrome: Considerations for Nerve Transfer Surgery

PURPOSE OF REVIEW

Cubital tunnel syndrome is the second most common compressive neuropathy, next to only carpal tunnel syndrome in its incidence. Severe states of disease do not respond to nonoperative management. Likewise, functional outcomes of cubital tunnel surgery decline as the disease becomes more severe. The relatively long distance from site of nerve compression at the elbow to the hand intrinsic muscles distally makes it a race between reinnervation of the muscle and irreversible motor endplate degeneration with muscle atrophy. Loss of intrinsic function can lead to severe functional impairment with poor dexterity and clawing of the hand. While decompressing the nerve at the site of compression is important to prevent further axonal injury, until recently, the only option to restore intrinsic function was tendon transfers. Tendon transfers aim to restore thumb side pinch and control clawing with addition surgery. They also require the sacrifice of wrist extensors or finger flexors. In the past decade, nerve transfers to the distal portion of the ulnar nerve innervating these intrinsic muscles, originally described for proximal ulnar nerve injury or transections, have become increasingly popular as an adjunct procedure in severe cubital tunnel syndrome. Physicians treating severe ulnar neuropathy must be aware of these nerve transfers, as well as their indications and expected outcomes.

RECENT FINDINGS

The so-called supercharged anterior interosseous nerve (AIN)-to-ulnar motor nerve transfer has become a mainstay for distal nerve transfers for ulnar neuropathy and/or injury. Ideal patients to undergo such a procedure demonstrate severe ulnar neuropathy on nerve conduction and electromyography studies, with reduced compound muscle action potential (CMAP) amplitude and fibrillations at rest. Recent studies demonstrate nerve transfers to be superior in intrinsic muscle reinnervation compared with nerve graft in the setting of large segmental nerve defects. Likewise, compared with decompression alone, patients undergoing the supercharge procedure are more likely to regain intrinsic function and less likely to need secondary tendon transfer surgeries. Finally, initial results for sensory nerve transfer to recover sensation in the ulnar-sided digits in severe cubital tunnel are more advantageous than for decompression alone. Distal nerve transfers offer a reliable, reproducible treatment option for the restoration of intrinsic hand function and protective sensation in the setting of severe cubital tunnel syndrome.

Subterminal key pinch dynamometry: a new method to quantify strength deficit in ulnar nerve paralysis

Precise pre- and postoperative assessments are fundamental to recording the quality of recovery after ulnar nerve repair. Because of its imprecision, manual muscle testing is being replaced by dynamometry to measure grasping and key-pinch strengths. However, both grasping and key pinch are dependent not only on the ulnar nerve but also the median and radial nerves. We propose to measure strength using a new sort of pinch, called the 'subterminal key pinch'. Strength was measured using a commercially available pinch meter. Patients applied pressure on the dynamometer with the interphalangeal joint of the thumb, maintaining the joint in extension to avoid enhancement of strength by the flexor pollicis longus. We examined 17 patients before ulnar nerve repair. Preoperatively, grasping strength was 46% of normal, while key pinch was 58%, pinch-to-zoom strength was 26% and subterminal key pinch only 7%. Subterminal key pinch was the most affected pinch with a strength deficit of over 90%.Level of evidence: IV.

Prior to Repair Functional Deficits in Above- and Below-Elbow Ulnar Nerve Injury

PURPOSE

Clinical deficits might vary, depending on whether an ulnar nerve lesion is above or below the elbow. Lack of strength and clawing are common manifestations of ulnar nerve paralysis. However, the magnitude of strength deficit relating to different pinch patterns and the rate and range of proximal interphalangeal extension deficits are poorly described.

METHODS

I prospectively evaluated 14 patients with above-elbow and 16 with below-elbow unrepaired ulnar nerve injuries. The completeness of flexion of the ring and little fingers was tested at the metacarpophalangeal and distal interphalangeal joints. Proximal interphalangeal joint extension lag of the ring and little fingers was assessed by goniometry, and adduction and abduction of the little finger. With dynamometers, I bilaterally evaluated grasp, key pinch, and pinch-to-zoom strength. Hand sensibility was evaluated with monofilaments.

RESULTS

Metacarpophalangeal flexion in the ulnar fingers was absent in all patients, whereas distal interphalangeal joint flexion was preserved in 29 of 30 patients. In above-elbow ulnar nerve injuries, there was no paralysis of the flexor digitorum profundus. One-third of patients exhibited no clawing. There were minimal differences between the rate of clawing and proximal interphalangeal extension lag in above- and below-elbow ulnar nerve lesions, or its occurrence in the ring or little finger. In relation to the normal hand, grasping, key pinch, and pinch-to-zoom decreased by 62%, 51%, and 75% compared with 59%, 61%, and 76% in below- and above-elbow injuries groups, respectively. In both groups, sensory deficits were predominantly over the little finger and ulnar side of the hand.

CONCLUSIONS

Minimal differences were observed in clinical deficits after above- and below-elbow ulnar nerve injuries. Hand weakness was the most frequent problem, whereas pinch-to-zoom strength was highly affected.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.