MEDIAN NERVE PALSY AND TRANSFERS

Introduction

Median nerve palsy is a condition resulting from damage to the median nerve at any point along its anatomical length. It has been regarded as the most devastating injury to a single upper extremity nerve because it leads to the loss of sensibility in addition fine motor control and opposition. The median nerve can be injured through numerous potential etiologies, including penetrating trauma, secondary to distal humerus fractures, or rarely, from a reduced fracture or elbow dislocation. Cases are classified based on their location, with high median nerve palsy applying to damage proximal to the innervation of the forearm muscles, which leads to loss of extrinsic finger flexion. Low median nerve palsy describes injuries distal to the elbow and leads to loss of thumb opposition and sensation. A tendon transfer is a surgical procedure used to treat median nerve palsy that usually involves the release of a tendon at its anatomic insertion site, rerouting the tendon, and finally reattaching it to a new insertion site either in another tendon or in a bone. It is a commonly used procedure that may be needed for non-repairable median nerve palsies, when there is a loss of muscle and tendon secondary to trauma, or for slowly progressing neurological disease.^1-4

Related Anatomy^1,4

Median nerve
- Arises from five roots of the brachial plexus through its lateral and medial cords
- Extends along the middle of the arm and enters the forearm between the two heads of the pronator teres (PT)
- It then runs deep to the flexor digitorum sublimis (FDS) and innervates all four of its muscle bellies
  - Also innervates the flexor carpi radialis (FCR) and palmaris longus (PL) muscles
- Anterior interosseous nerve (AIN)
  - Deep motor branch of median nerve
  - Begins ~6–8 cm distal to the medial epicondyle
  - Innervates the flexor pollicis longus (FPL), flexor digitorum profundus (FDP) of the index and long fingers, and the pronator quadratus (PQ) muscles
- Palmar cutaneous branch
  - Arises a few centimeters proximal to the wrist
  - Provides sensation to the radial palm
- Recurrent motor branch
  - Innervates thenar muscles
    - Abductor pollicis brevis (APB)
    - Opponens pollicis
    - Superficial head of flexor pollicis brevis (FPB)
- Distal branches
  - Innervate the volar aspect of the thumb, index, long, and radial half of fourth finger
- Short motor branches
  - Innervate the index and long finger lumbricals

Signs and Symptoms^2,5

Typical symptoms of median nerve palsy include:
- Loss of flexion at the thumb interphalangeal (IP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints
- Loss of thumb opposition
- Sensory deficits
- Reduced grip strength
- Loss of fine motor control
A tendon transfer is usually indicated when there is no potential for median nerve palsy to improve, including those that are physically irreparable (e.g. root avulsions, injuries not improved after direct nerve repair or grafting, and failed nerve transfers)
Other indications for tendon transfer include:
- Median nerve palsies that present too late for muscle reinnervation to occur due to fibrosis of the motor end plate
- Loss of muscle or tendon following trauma
- Central neurologic deficits
- Tendon ruptures in patients with rheumatoid arthritis

Physical Examination and Work-up^2,6,7

Before considering a patient for a tendon transfer, the clinician should obtain an accurate history and perform a physical examination
The physical examination includes detailed muscle testing and range of motion (ROM) assessments of the wrist, hand, and finger. An inventory of both the functioning and nonfunctioning muscle-tendon units should be performed.
- Both motor function and sensation must be evaluated to identify any deficits present, distinguish between lesion types, and determine appropriate indications for correction
  - The thumb’s carpometacarpal (CMC), metacarpophalangeal (MP), and IP joint should all be carefully assessed and compared with the contralateral side
- Detailed examinations go to muscle testing by nerve or to specific muscle examinations in the exam test and signs section
- Findings may include an inability to make an “OK” sign and loss of sensation
In high median nerve palsies, ulnar nerve function and hand vascularity should also be evaluated to detect for a possible combined nerve injury
Median nerve palsies can usually be diagnosed by the physical exam alone, but electrodiagnostic testing may also be needed
- Electromyography (EMG) and nerve conduction velocity (NCV) testing can be used for determining the exact location and extent of the initial injury
- EMG and NCV testing can also be helpful for detecting signs of early nerve recovery

Basic Science and Principles of Tendon Transfers

When evaluating a patient for a tendon transfer and planning out the procedure, several core principles must be considered. Adhering to these principles will increase the chances of a successful outcome, while not doing so can lead to a failure. The core principles of tendon transfers are described below.⁸

Synergy^2,8

Synergy principle: certain muscle groups usually work together to perform a function or movement (e.g. wrist flexion and finger extension; wrist extension and finger flexion)
Finger flexion and wrist flexion are not synergistic movements
- Therefore, a wrist flexor transferred to restore finger extension will adhere to synergetic principles, while a wrist flexor transferred for finger flexion will not function synergistically
Synergistic transfers are usually easier to train and are preferable to non-synergistic transfers; therefore, it is advised to perform synergistic transfers whenever possible, although non-synergistic transfers may be the only option available in some cases

Passive mobile joints^2,8,9

Tendon transfers cannot mobilize stiff joints, and the procedure will fail if a joint is too stiff
Passive mobility is therefore a prerequisite to tendon transfer: the joints controlled by the transferred tendon must have nearly full passive ROM before the procedure to achieve optimal post-tendon transposition
The donor muscles must be tested for strength before performing transfer procedures
Pre-operative hand therapy is often needed to improve passive ROM if it is not normal
In some cases, joint release may be necessary before the tendon transfer

Soft tissue equilibrium^2,8

Tendon transfers must pass through a healthy bed of soft tissue that is free of scar tissue, inflammation, and edema. A healthy soft tissue bed allows the tendon to glide freely with pliable skin and minimizes adhesions
In most cases, this will entail the transfer passing through healthy subcutaneous fatty tissues
After a soft tissue injury, the surgeon must allow sufficient time to pass for inflammation and edema to fully subside before performing tendon transfers
If a healthy, soft bed is not present and/or the transfer must pass through an area in which severely scarred tissue is present, the surgeon can either excise the scar and reconstruct the bed with a flap or plan an alternative transfer through a healthier bed of tissue

Adequate strength^2,8

The strength of the donor muscle-tendon unit being must be strong enough to allow the desired movement(s) but must not be so strong that it disrupts the extensor/flexor balance
- When the donor is too weak, movement and function will not be adequate
- When the donor is too strong, movements become unbalanced and there is inappropriate posture at rest
Therefore, the strength of the muscle-tendon unit should be either normal or near normal and under voluntary control in pre-operative testing. Strength at 5/5 is ideal because the transferred muscle will usually loose a grade after transfer.
For additional information see the standard muscle testing options in the examination section below

Sufficient amplitude¹⁰

A muscle’s amplitude is a function of its sarcomere length
The transferred muscle-tendon unit must have enough amplitude to successfully perform the function of the tendon being replaced
- The sarcomere length and work capacity of the muscle being transferred must provide enough muscle shortening during contraction to provide adequate shortening of the muscle-tendon unit and produce the needed ROM of the joints that need to be mobilized
The flexor carpi ulnaris (FCU) has the greatest work capacity of the wrist motors, but due to its significant role in wrist function, using it for tendon transfers has been called into question

Straight line of pull^8,10

Transferred tendons must have a straight line of pull from their origin through unscarred soft tissue to the new insertion point
Changes in direction can create points of friction, which reduces the potential force, power, and amplitude of the transferred muscle-tendon unit: changing direction by only 40° will lead to a significant decrease in force
Tendon transfers cannot perform two separate functions at once, especially if the line of pull is not straight
If there is a second point of insertion because the tendon has been split to insert on two separate insertion sites and half of the tendon does not follow a straight vector, then no force will be directed to this second insertion point. There are rare exceptions to this rule such as a Stiles-Bunnell intrinsic transfer. This means usually each transfer such have only one function not two.

Expendable donor^2,8

The donor muscle-tendon unit must be expendable, meaning another tendon—or tendons—is left intact that can continue to adequately perform the original function of the transferred muscle-tendon unit
Restoring a given movement only to lose another equally important movement in the process is not beneficial
Example: if one of the wrist flexors (e.g. the FCR) is transferred, then the FCU must be intact and functioning normally so wrist palmar flexion function is preserved after the transfer

Tension of the transfer⁸

The amount of passive tension set is a critical component of the procedure: the surgeon should ensure that the tension in the transfer is slightly tight and be aware of the recommended positioning of the elbow, wrist, and digits when adjusting this tightness
The surgeon should also use the wrist tenodesis effect to gently test the transfer passively before finalizing the tightness of the tendon transfer insertion into its new origin

Donor of adequate excursion^2,5,8,10

The excursion of the donor muscle-tendon unit should be adequate enough to achieve the desired hand movement, meaning the excursion of the transferred tendon is comparable to that of the recipient tendon
Excursion of various muscles
- Wrist extensors and flexors: 33 mm
- Finger extensors: 50 mm
- Finger flexors: 70 mm
The tenodesis effect of the wrist can add another 20–30 mm of finger tendon excursion

Single function per transfer^2,5,8

A single tendon should only be used to restore a single function, as attempting to restore multiple functions will compromise strength and movement
One exception is that a single muscle-tendon unit can restore the same movement in more than one digit (see #6)

Other

Incisions used for tendon transfers should not parallel the route of the transferred tendon because this will increase the chance of adhesions and loss of tendon gliding
Use transverse incisions so there is less opportunity for the transferred tendon to scar to the surgical incision
Tendon transfers will often adhere to the first fibrous structures that they touch, so ideally the first fascial (collagen) structure should be at the new insertion site of the transferred tendon. This fact also means that transfers are not reliably be used to produce forearm rotation.

Timing and planning^7,10

Timing of tendon transfers for median nerve palsy is classified as either early or late
- Early tendon transfer
  - Act as an internal splint
  - Performed within 12 weeks of injury
- Late tendon transfer
  - Performed to restore function when recovery is unlikely
  - Can be performed between 6–18 months after injury
Determining the optimal timing should be contingent on several factors, including:
- The etiology of the injury
- The patient’s prognosis
- Whether there is a clear indication that the injured nerve will not regenerate
- Patient preference
If functional recovery is not possible, transfers should be performed immediately after the patient is ready. If nerve regeneration is expected to occur, the surgeon should wait until it’s possible to determine the level of functional recovery.
Planning for tendon transfers must include making an inventory of those muscle-tendon units that are functioning normally and those that are no longer functioning or have been removed by injury
The surgeon must do appropriate muscle testing to determine the muscle grade of each remaining muscle-tendon unit. For additional information, see the standard muscle testing options in the examination section below.

High vs. low median nerve palsy^1,2,7

High median nerve palsy
- Proximal to the elbow
- Very uncommon
- Leads to loss of:
  - Thumb IP joint flexion
  - Index and long finger flexion at the PIP and DIP joints
    - Reduced thumb and finger flexion results in lack of fine motor control
  - Forearm pronation strength
  - Thumb opposition
    - Produces significant hand function impairments
- Can also cause sensory deficits involving palmar surface of the thumb, index, long, and radial half of the fourth finger
- Reduced grip strength
- Wrist flexion typically remains intact
Low median nerve palsy
- Distal to the elbow
- Usually less devastating than high median nerve palsy because some sensory reinnervation is likely after repair
- Leads to loss of
  - Abduction
  - Thumb Opposition
  - Forearm pronation
- Sensory deficits in the thumb, index, long, and radial half of the fourth finger
- Extrinsic muscles supplied by median nerve are spared

Combined median and ulnar nerve palsy^1,10

Challenging injuries that typically result from severe trauma and are associated with substantial soft tissue, vascular, and bony injuries
Multiple muscle-tendon units may be lacerated and require repair, meaning they are unsuitable donors for tendon transfer. Further complicating reconstruction is that the loss of sensibility and proprioception is usually more profound than in single nerve palsies.
Combined low median and ulnar nerve palsy
- Most common combined injury
- Typically occurs secondary to a laceration on the volar side of the wrist
- Leads to the following symptoms:
  - Complete palmar numbness throughout the hand, fingers, and thumb
  - Clawing of all four fingers
  - Loss of finger flexion integration, key pinch, and thumb opposition
Combined high median and ulnar nerve palsy
- Less common, but far more severe injury and more difficult to treat than combined low median-ulnar nerve palsy
- Leads to the following symptoms:
  - Loss of key pinch and simple grip strength
  - Loss of finger flexion
  - Loss of thumb opposition
  - Profound loss of sensation

ICD-10 Codes

Diagnostic Guide Name

MEDIAN NERVE PALSY AND TRANSFERS

ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

DIAGNOSIS	SINGLE CODE ONLY	LEFT	RIGHT	BILATERAL (If Available)
MEDIAN NERVE PALSY DUE TO LESION		G56.12	G56.11	G56.13
MEDIAN NERVE PALSY DUE TO INJURY, FOREARM LEVEL (LOW)		S54.12X_	S54.11X_
MEDIAN NERVE PALSY DUE TO INJURY, UPPER ARM LEVEL (HIGH)		S44.12X_	S44.11X_

Instructions (ICD 10 CM 2020, U.S. Version)

THE APPROPRIATE SEVENTH CHARACTER IS TO BE ADDED TO EACH CODE FROM CATEGORY S44 AND S54

A - Initial Encounter

D - Subsequent Routine Healing

S - Sequela

ICD-10 Reference

Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams

Median Nerve Palsy

Severe thenar atrophy secondary to chronic carpal tunnel syndrome.
Thenar atrophy where attempted opposition leads to thumb adducting across the palm.
Note thumb opposition in normal hand and the inability to separate the thumb from the palm in patient with the median nerve palsy.
Combined chronic median and ulnar nerve palsies with severe atrophy.
Most median nerve palsies are secondary to chronic carpal tunnel syndrome or median nerve lacerations where recovery after nerve repair is incomplete or fails.

Pathoanatomy Photos and Related Diagrams

Median Nerve Anatomy

Muscles innervated by the Median Nerve.
Anterior (palmar or volar ) Sensation by Nerve: 1 = median nerve; 2 = dorsal radial sensory nerve; 3 = ulnar nerve; 4 = lateral antebrachial cutaneous nerve; 5 = medial antebrachial cutaneous nerve; 6 = radial dorsal antebrachial cutaneous nerve; 7 = medial brachial cutaneous nerve; 8 = intercostobrachial nerve; 9 = axillary nerve (superior lateral brachial cutaneous nerve.
Posterior (Dorsal) Sensation by Nerve: 1 = median nerve; 2 = dorsal radial sensory nerve; 3 = ulnar nerve (dorsal ulnar sensory nerve); 4 = lateral antebrachial cutaneous nerve; 5 = medial antebrachial cutaneous nerve; 6 = posterior brachial cutaneous nerve, inferior lateral cutaneous nerve, posterior antebrachial cutaneous nerve; 7 = medial brachial cutaneous nerve; 8 = intercostobrachial nerve; 9 = axillary nerve (superior lateral brachial cutaneous nerve.

Symptoms

History of median nerve injury or dysfunction

Decreased sensation and/or painful tingling in the thumb, index, long and ring fingers

Weak pinch and grip

Inability to flex the thumb or the tip of the long and/or index fingers

Typical History

A typical patient is a 56 y. o. right handed female who has had right carpal tunnel syndrome for many years but never sought medical treatment. Now the patient cannot raise her thumb out of the plane of her palm. She is complaining of constant numbness in her fingers and painful tingling her fingers. She also notes difficult with buttoning and similar activities of daily living. The exam shows decreased sensation in the entire median nerve distribution, marked thenar atrophy, absent opposition of the thumb and a positive median nerve compression test at the wrist. The EMG/NCV was consistent with severe carpal tunnel syndrome. She now is seeking a second opinion regarding her surgical treatment options. The first hands surgeon she saw recommended a carpal tunnel release and a tendon transfer called an opponensplasty.

Positive Tests, Exams or Signs

Work-up Options

Electrophysiological Testing - EMG/NCV

Treatment Options

Treatment Goals

Improve hand and upper extremity function by:

Improving sensation and decreasing paresthias
Improving motor function appropriate median nerve palsy tendon transfers.

Conservative

Hand therapy, splinting and various modalities can improve the functional capacity of a patient with a median nerve palsy but unfortunately cannot replace the missing median nerve functions.
Hand therapy can improve the active and passive range of motion in the upper extremity and hand prior to tendon transfers.
Hand therapy can also improve the strength of the muscles that are not denervated in the upper extremity with a median nerve palsy.
However, a complete median nerve palsy that is not a simple temporary neuropraxia cannot be functional corrected without surgery

Operative

Options^1-3,5,7

Tendon transfers should be performed for median nerve palsy when recovery is unlikely, either spontaneously or after nerve repair
There are over forty muscles in the forearm and hand, many of which perform overlapping functions. Therefore, many options are available when selecting a working muscle-tendon unit to replace a non-working muscle-tendon unit in tendon transfer procedures. More than 50 tendon transfer techniques have been described, and the surgeon must therefore decide on which is most appropriate for each patient.
Tendon transfer procedures for median nerve palsy should aim to restore thumb IP flexion, thumb opposition, and flexion of the index and long fingers
Low median nerve palsy
- Restoration of thumb opposition
  - Accomplished with an opponensplasty procedure. The four most common techniques are:
    - Extensor indicies proprius (EIP) to abductor pollicis brevis (APB) (Burkhalter transfer)
      - The EIP should be divided over the index MP joint and passed proximally under the extensor retinaculum
      - The tendon is then routed around the ulnar side of the wrist, passed subcutaneously through the palm, and woven into the APB insertion
    - Abductor digiti minimi (ADM) to APB (Huber transfer)
      - The ADM is released from its insertion, inverted 180°, and then inserted on the APB insertion
      - Transfer provides bulk to the thenar eminence because the entire muscle is turned over in this area
      - Strength and excursion are well matched to the deficit
      - Transfer is synergistic
      - Particularly useful for patients with combined median and radial nerve palsies
    - FDS of fourth finger to APB (Bunnell or Royle-Thompson transfer)
      - Also known as the superficialis opponensplasty
      - Divides fourth finger FDS distally, retrieving the FDS proximal to the carpal tunnel, re-directing the tendon distally through the FPL sheath, and inserting it into the thumb
      - Thompson transfer is a modification that re-directs the tendon subcutaneously to the thumb instead of the FPL tendon sheath
      - Bunnell transfer reroutes the tendon around a looped strip of FCU to achieve a more effective line of pull
      - Can only be performed on low median nerve palsies
    - PL to APB (Camitz transfer)
      - Primarily indicated for patients with carpal tunnel syndrome
      - PL tendon is harvested with an extension of superficial palmar fascia and passed subcutaneously to the thumb, then attached to the APB insertion
        Adequate amount of palmar fascia must be harvested to provide enough length
      - Biggest advantages: lack of functional loss and ability to be easily performed concomitant with carpal tunnel release
      - Primary disadvantages: the PL is a weak motor and true opposition is not restored
High median nerve palsy
- Restoration of thumb opposition
  - Achieved through any of the four opponesplasty procedures described above
- Restoration of thumb IP flexion
  - Brachioradialis to FPL transfer
    - Brachioradialis is the preferred donor for thumb IP flexion
    - Brachioradialis tendon is harvested from its insertion at the radial styloid process using a radial-sided forearm incision, and then woven into the FPL tendon proximal to the wrist crease
    - Transfer should be tensioned so the thumb MP and IP joints are in 30° flexion and wrist is in a neutral position
- Restoration of index and long finger DIP and PIP flexion
  - ECRL to FDP transfer
Combined median and ulnar nerve palsy^1,5,10
- Due to the severity of these injuries and the limited motor nerves available for use, standardized tendon transfers are often not possible. Thus, surgical treatment must instead be individualized, and multiple procedures are usually required. Tenodesis and capsulodesis procedures may also be needed to supplement the tendon transfer.
- Attention to the principles of tendon transfer is particularly important for these injuries to increase the chances of a successful outcome. Surgeons must carefully think out the staging and timing of each of the multiple procedures used and should only perform tendon transfer procedures simultaneously that can be rehabilitated together.
- Combined low median-ulnar palsy
  - Requires restoration of opposition and key pinch, reintegration of MP and IP joint flexion, and treatment of clawing
  - Available donors for reconstruction: muscle-tendon units innervated by the radial nerve and more proximal muscle-tendon units innervated by the median and ulnar nerve that are uninjured
  - Surgical reconstruction options
    - Extensor carpi radialis brevis (ECRB) or FDS transfer for key pinch
    - EIP opponensplasty or FDS opponensplasty for thumb opposition
    - ECRL or brachioradialis transfer to integrate finger flexion and improve clawing
    - Brand technique
      - Can be used for clawing of all four digits
      - FCR or ECRB tendon is split into 2–4 tails based on the number of fingers being addressed
      - The tails are then extended using free tendon grafts and attached to the radial lateral bands of the long, fourth, and little fingers and the ulnar lateral band of the index finger
- Combined high median-ulnar palsy
  - Primary reconstruction goals: restoration of key pinch, opposition, and simple grip strength
  - Only muscle-tendon units innervated by the radial nerve are available as donors
  - Surgical reconstruction options
    - ECRB, brachioradialis, EIP, or FDS transfer for restoring key pinch
    - ECRL to FDP transfer for restoring finger flexion and grip strength
    - EIP, EPL, or ECU opponensplasty for restoring thumb opposition
    - PT to ECRB transfer for restoring wrist extension
    - FDS transfer for restoring finger and thumb extension

Nerve Transfers¹³

Nerve transfer for brachial plexus reconstruction are well defined in the literature; however, their usefulness for reconstructing median nerve lacerations is still evolving.¹However, nerve transfer(s) have been gaining in popularity as an alternative to tendon transfers/nerve grafting for patients with severe proximal nerve injuries, but the field is still evolving with new techniques being described as microsurgical techniques improve and more patients experience good outcomes.
Proposed Advantages of Nerve Transfer
- Able to also restore sensory function
- Multiple muscle groups can be reinnervated with a single nerve transfer
- Muscle origin/insertions are not disrupted
Principles of Nerve Transfer
- Ideally pick a donor nerve near the motor endplates of the target muscle to minimize time to innervation. A shorter distance means shorter time for reinnervation
- Use expendable or redundant nerve fibers
- Use donors that have a large number of axons
- Use donors that already innervate synergistic muscles with the target muscle (helps facilitate re-education)
- Using donors that match the target is ideal, i.e. motor donors for motor targets, sensory donors for sensory targets
- Re-innervation after 12-18 months may be impossible, as prolonged denervation will cause muscle cell death and fibrosis.
Nerve transfers for Median Nerve Palsy
- Goals: Restore forearm pronation, thumb opposition, finger flexion, median sensation
- Pronation – 1 or 2 branches of FDS are transferred to non-functioning branches to pronator teres. Alternative donors include the brachialis branch of the musculocutaneous nerve or the brachioradialis branch of the radial nerve
- Finger flexion – medial antebrachial cutaneous or medial brachial cutaneous can be transferred to the AIN to restore finger flexion
- Thumb Opposition – branch from AIN to the pronator quadratus can be transferred to the median nerve

Treatment Photos and Diagrams

Tendon Transfers for Median Nerve Palsy - Huber Transfer

Huber opponensplasty - often used with children with congenital thenar hypoplasia that frequently accompanies radial agenesis. In step 1 the abductor digits minimi is detached distally, free from surrounding structure and left attached to the neurovascular bundle and pisiform area.
Huber opponensplasty - In step 2 the mobilized abductor digits minimi is brought through the subcutaneous tissues of the thenar eminence. The detached distal abductor digiti minimi tendon is sutured to the abductor pollicis brevis insertion site. The neurovascular bundle must be handled delicately in order to maintain the innervation and blood supply of the abductor digiti minimi. This transfer supplies opposition and improved appearance of the thenar eminence by adding muscle bulk to the thenar area.

Tendon Transfers for Median Nerve Palsy - Camitz Transfer

Patient with chronic carpal tunnel syndrome and severe thenar atrophy. Note distal end of the palmaris longs (PL) above dotted line.
Camitz Transfer – Stage 1: During an open carpal tunnel release, the distal end of the palmaris longus is identified and released from its forearm attachments while its connections to the palmar aponeurosis are left intact. The palmar aponeurosis extension is dissected off the transverse carpal ligament and surrounding structures.
Camitz Transfer – Stage 2: The open carpal tunnel release has been completed. The palmaris longus and the attached palmar aponeurosis (fascia) extension are passed subcutaneously superficial to the abductor muscle to abductor aponeurosis where it is sutured to the radial aspect of the extensor hood at the thumb MP joint level. The skin incisions for releasing the palmaris longus, doing the carpal tunnel release and for suturing of the transfer to the extensor hood are sutured.

Tendon Transfers for Median Nerve Palsy - FDS IV Opponensplasty

Diagram of FDS IV Opponensplasty. Note four incisions and pulley choices. Loop pulley indicated in FCU is paralyzed.
Incisions for FDS IV Opponensplasty and carpal tunnel release
FDS IV Opponensplasty without a carpal tunnel release. FDS release at base of the ring, passed through the carpal tunnel to the distal wrist crease near the FCU.
FDS IV passed around the FCU. Clamp passed subcutaneously from thumb MP to wrist incision to grasp the FDS (arrow). Insert shows both FDS slips at the MP joint area. FDS to sutured to the abductor conjoined tendon.
FDS IV Opponensplasty & CTR. FDS passed around the FCU (1) which serves as a pulley. FDS passed subcutaneously to CT incision (2). Next FDS will be passed subcutaneously to radial side of the thumb MP joint (3) and sutured to the conjoined tendon.
Incisions closed. Wrist dorsiflexion flexes thumb IP joint and opposes thumb to base of long finger. With wrist neutral thumb should align with he base of the index.
Two weeks after surgery FDS transfer opposing thumb actively.

Tendon Transfers for Median Nerve Palsy - EDM Opponensplasty

Before doing an EDM opponensplasty, test the muscle grade (strength) of the EDM. A muscle testing grade of 5/5 (normal) is ideal for transfer.
The drawing shows the EDC, EDM and sagittal bands. The EDM is release from the EDC and sagittal band by cutting a proximal based triangular segment of tendon out of the extensor hood. After release of both EDM slips the sagittal band is repaired to the EDC.
1 - both slips of the EDM; 2 - EDC (Juncturae tendinum)
1 - both slips of the EDM; 2 - EDC (Juncturae tendinum)
Use both EDM slips for this opponensplasty. If one slip is left attached to the finger extensor mechanism, the finger will extend but the thumb opposition WILL BE LOST.
A tendon passer has been inserted at the carpal tunnel incision, through the subcutaneous tissues to the dorsal ulnar wrist. The EDM has been placed in the jaws of the tendon passer. The EDM will be pulled through the subcutaneous tunnel.
A clamp is passed subcutaneously from the thumb abductor insertion to the CT incision. The tip of the clamp (1) grasps the sutures that have been placed in the EDM (2). The sutures and tendon will be pulled through the tunnel to the insertion site.
The EDM tendon is ready for suturing to the conjoin tendon of the AbP, FPB & Opponens.
The EDM has been sutured and the EDM opponensplasty is complete.
With the wrist in neutral the thumb aligns with the base of the index finger.

Tendon Transfers for Median Nerve Palsy - EIP Opponensplasty

Step 1 EIP Opponensplasty: EIP (Extensor Indicis Proprius) release from insertion at index MP joint level (1). EDC (Extensor Digitorum Communis) left intact. “V” defect in the index extensor hood to be repaired. EIP released back to level of the wrist(2).
Step 2 EIP Opponensplasty: EIP (Extensor Indicis Proprius) is brought out of the fourth extensor compartment through the subcutaneous tissue with a tendon passer into incision 3. Next the EIP will be passed to incision 4 in the ulnar palm near the pisiform.
Step 3 EIP Opponensplasty: Once the EIP (Extensor Indicis Proprius) is brought into incision 4, a tendon passer retrieves the EIP at the 4th incision, brings the tendon distal to the pisiform, through the subcutaneous tissues to incision 5. The EIP is then sutured into the conjoin tendon as shown.

Tendon Transfers for High Median Nerve Palsy - BR to FPL & ECRL to FDP

The brachioradialis has been released from its insertion site at the radial styloid. The FPL has been transacted at the musculotendinous junction. Next the FPL has been sutured into the brachioradialis tendon.
The extensor carpi radialis longus tendon (ECRL) has been released from the base of the index metacarpal and transferred to the combined flexor digitorum profundus tendons (FDP II - V). The extensor carpi radialis longus is passed through the profundus tendons which have been sutured together. Alternatively, the extensor carpi radialis longus tendon can be split into two halves with the flexor digitorum profundi sutured to the ECRL as shown in the insert.
Note severe thenar atrophy and poor flexion of FPL and FGP II & III
Note incision for ECRL release and intact extensor tenodesis affect.
ECRL and BR are released and ready for transfer to FDP II&II and FPL respectively.
Note in insert the extensive release needed for the BR. Both BR and ECRL being checked for length prior to transfer.
Transfers have been complete. Note passive thumb IP flexion and finger flexion with wrist dorsiflexion.

Huber Transfer
For ASSH's Hand-e Surgical Video of a Huber Transfer:

Opponensplasty
For ASSH's Hand-e Surgical Video of an Opponensplasty:

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Hand Therapy

Postoperative care and rehab^1,10

Following all tendon transfer procedures, patients should be outfitted with a bulky plaster splint or cast to take tension off the transfer
- If transfer was intended to improve clawing, splint should keep the MP joints flexed and IP joints extended
- If an extensor muscle-tendon unit is used, the wrist should be placed at 30° of extension
  - For FDS transfers, the wrist should be placed in more neutral position or slightly flexed
1–2 weeks post-surgery
- Splint should be changed to check the incisions and re-fit the splint
4 weeks post-surgery
- Patient should be maintaining mobility in the non-immobilized joints of upper extremity during the first four weeks
- Patient begins physical or occupational therapy and transitions to a thermoplastic splint, which is to be worn except when doing the prescribed exercises
- Mobilization begins with gentle active and assisted ROM exercises. Only one joint should be mobilized at a time to avoid excessive tension on the transfer.
6 weeks post-surgery
- Patient begins muscle retraining and performing exercises that activate muscles used in the transfer
- Electrical stimulation and biofeedback may be used to assist retraining
8 weeks post-surgery
- Begin strengthening exercises
- Splint can be weaned off over next four weeks
12 weeks post-surgery
- Resume full activity
For combined median and ulnar nerve palsies, rehabilitation goals should be realistic since it is extremely unlikely that all the lost function will be regained. Proper exercise and splinting are necessary to prevent contractures from developing.

Complications

Infection
Bleeding
Blood vessel or nerve damage
Hand stiffness or weakness
Tendon rupture at repair site
Tendon adhesions
Transfer weakness
Extensor lag^3,5

Outcomes

In general, outcomes are better for patients who retain median nerve sensibility or are expected to experience a return of sensation¹
In one study of 40 hands managed with the EIP transfer, 87.5% of patients reported good or excellent results, meaning that with the thumb IP joint extended, they could either touch the tip of the index or long finger (“good” result) or the fourth or little finger (“excellent” result)¹¹
Potential complications of opponensplasty procedures include extensor lag of the index finger after the EIP transfer and swan-neck deformity and digital flexion contracture after the FDS transfer³
Outcomes of combined median and ulnar nerve palsies are generally worse than those of single nerve palsies due to the severity of the associated injuries responsible and lack of donor muscle-tendon units. In combined high median-ulnar nerve palsies, even multiple reconstructive operations often fail to help the hand function much better than a prosthesis.¹

Key Educational Points

The power of a muscle is related to his cross-sectional area. The transferred muscle will most likely lose some power. Therefore, only muscles rated 4+ or better should be considered acceptable donor motors.¹⁰
A muscles work capacity is calculated as the product of the muscle power times its amplitude¹⁰
There is still controversy regarding the optimal timing for tendon transfers. Most experts agree it’s necessary to wait until sufficient time has elapsed to determine that further nerve recovery will not occur, but some new research suggests that immediate transfers should be performed in certain situations (e.g. a gap of >4 cm between nerve ends, when the nerve is in a deep wound of scar tissue, and with major tissue loss).⁹
If sensation is unable to be restored, a tendon transfer may also fail to restore movement¹
- In combined median and ulnar nerve palsies, it is crucial to consider the strength of the antagonist muscles to avoid overcorrection, as small alterations in forces can have a profound impact on the overall balance of the hand¹²

References

DM and Chung, KC. Tendon transfers: Part II. Transfers for ulnar nerve palsy and median nerve palsy. Plast Reconstr Surg 2009;124(3):212e-21e. PMID: 19730287
Seiler, JG, 3rd, Desai, MJ and Payne, SH. Tendon transfers for radial, median, and ulnar nerve palsy. J Am Acad Orthop Surg 2013;21(11):675-84. PMID: 24187037
Loewenstein, SN and Adkinson, JM. Tendon Transfers for Peripheral Nerve Palsies. Clin Plast Surg 2019;46(3):307-315. PMID: 31103075
Isaacs, J and Ugwu-Oju, O. High Median Nerve Injuries. Hand Clin 2016;32(3):339-48. PMID: 27387077
Carl, DJ and Habusta, SF.Hand Tendon Transfers. In: StatPearls.Treasure Island (FL): 2020. PMID: 29083655
Sridhar, K. Tendon transfer for median nerve palsy. Indian J Plast Surg 2011;44(2):357-61. PMID: 22022046
Ratner, JA, Peljovich, A and Kozin, SH. Update on tendon transfers for peripheral nerve injuries. J Hand Surg Am 2010;35(8):1371-81. PMID: 20684937
Sammer, DM and Chung, KC. Tendon transfers: part I. Principles of transfer and transfers for radial nerve palsy.Plast Reconstr Surg 2009;123(5):169e-177e. PMID: 19407608
Bumbasirevic, M, Palibrk, T, Lesic, A, et al. Radial nerve palsy. EFORT Open Rev 2016;1(8):286-294. PMID: 28461960
Leddy, JP and Leddy, TP. (1997). Tendon Transfers in the Hand and Forearm, in Dee R et al (Eds.) Principles of Orthopaedic Practice. New York: McGraw-Hill, 1152-1158.
Anderson, GA, Lee, V and Sundararaj, GD. Extensor indicis proprius opponensplasty. J Hand Surg Br 1991;16(3):334-8. PMID: 1960505
Wilbur, D and Hammert, WC. Principles of Tendon Transfer. Hand Clin 2016;32(3):283-9. PMID: 27387072
Weber RV, Mackinnon SE. Nerve transfers in the upper extremity. J Hand Surg Am. 2004; 4(3): 200-213.

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