Tendon Transfers
Warren C. Hammert
Ann E. van Heest
Michelle A. James
Christine Kwak
George S.M. Dyer
Brandon E. Earp
Barry P. Simmons
Kimberly L.Z. Accardi
Basic Principles
Tendon transfers involve using a functional muscle tendon unit to replace a lost function. This loss of function can be due to a peripheral nerve injury, spinal cord injury, stroke, traumatic brain injury, cerebral palsy, or any other cause. The more closely the tendon to be transferred resembles the nonfunctioning muscle tendon unit, the more likely it will be successful. Several principles should be considered prior to beginning the transfer and all these variables play an important role in determining the most optimal transfer.
I. Correction of Contracture
All joints should be supple with full passive motion prior to tendon transfer, as postoperative active motion will not be greater than preoperative passive motion. If the joint does not have full passive motion, this is corrected prior to tendon transfer by contracture release.
II. Tissue Equilibrium
The optimal time should not be until the scars are mature, the joints are supple, and the edema has resolved. Every effort should be made to place the transfers in healthy tissue, even if this means performing a different transfer. When a bed of healthy tissue is not present, consideration should be given to resurfacing with vascularized fasciocutaneous flaps prior to tendon transfer.
III. Straight Line of Pull
The most efficient tendon transfer is one that passes in a straight-line from its origin to the site of insertion.
IV. One Tendon—One Function
It is obvious that a tendon cannot be used for two different functions (digital flexion and extension), but the effectiveness of the transfer is reduced when trying to provide two similar functions (digital extension and thumb extension), as the transfer will only effectively move the joint to which it is most tightly attached.
V. Strength
The tendon chosen for transfer must have adequate strength to perform its new function. A muscle loses roughly one MRC grade of strength following transfer, i.e., a muscle graded at 5/5 might decrease to 4+/5 following transfer. As a general rule, muscles that have been denervated and have subsequently recovered are not good donor muscles. In order to successfully perform tendon transfers, an understanding of the relative strengths of the muscles in the forearm and hand should be obtained (Table 11.1). When choosing a muscle to transfer, one would prefer to have a muscle of the same or greater strength as the donor.
VI. Amplitude of Motion
It is difficult for a muscle to replace one with a greater excursion. By rough estimation, tendons that insert at the wrist level have 30 mm of total excursion, the digital extensors have 50 mm of excursion, and the digital flexors have 70 mm of excursion (Table 11.2).
It can also be stated that muscles attaching at the wrist have about 30 mm excursion, muscles attaching around the metacarpophalangeal (MP®MCP) joints have 50 mm of excursion, and muscles attaching nearer the finger tips have about 70 mm of excursion. These are general rules and the specific excursions are slightly different for the flexor pollicis longus (FPL) and the flexor digitorum superficialis (FDS) tendons.
To increase the amplitude of a given muscle, a transfer can incorporate more than one joint to allow the tenodesis effect to augment amplitude. This occurs when a wrist
flexor is transferred to a digital extensor. The wrist flexor has an amplitude around 30 mm, but this can be used to restore motion in a muscle, which normally has 50 mm excursion by flexing the wrist and allowing the digital extension to be augmented through tenodesis.
flexor is transferred to a digital extensor. The wrist flexor has an amplitude around 30 mm, but this can be used to restore motion in a muscle, which normally has 50 mm excursion by flexing the wrist and allowing the digital extension to be augmented through tenodesis.
TABLE 11-1 Relative strength of muscles available for transfer | ||||||||||||||||||||||||
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TABLE 11-2 Excursion muscles available for transfer | ||||||
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VII. Synergy
A transfer will be more effective and easier for the patient to use if the action of the transferred muscle is synergistic to the one it is replacing. Since wrist extension is synergistic with digital flexion and wrist flexion with digital extension, these reciprocal actions are to be kept in mind when performing a transfer.
VIII. Expendable Donor
The transfer of a tendon should not result in loss of a function. Therefore, at least one wrist flexor and extensor should be maintained.
IX. Arthrodesis
It is generally best to avoid arthrodesis to stabilize a joint as patients can use a mobile joint to their advantage, even if there is limited voluntary control of the joint. For example, a patient with a supple wrist may have minimal wrist control, but can supinate the forearm, allowing for wrist extension through gravity and attendant digital flexion via tenodesis to help with grasp.
X. Classification
Peripheral nerve injuries are generally classified as high (elbow level) or low (wrist level). They are also classified a single nerve injuries or combined (more than one) nerve injuries.
XI. Operative Technique
In tendon transfer surgery, the functional muscle tendon unit is repaired to the nonfunctional tendon using a strong weave to connect the tendons and decrease the chance for separation of the two tendons. This is commonly completed with three Pulvertaft weaves, in which one tendon is passed through the substance of the second tendon, interlocking the tendons and securing them to each other, creating a strong repair. The tension is set so as to allow for some slight postoperative stretch, as it is rare to create
a transfer that is too tight. The postoperative program varies, depending on the type of transfer, but generally involves a period of three weeks’ immobilization, followed by active and passive mobilization.
a transfer that is too tight. The postoperative program varies, depending on the type of transfer, but generally involves a period of three weeks’ immobilization, followed by active and passive mobilization.
Peripheral Nerve
I. Radial Nerve Palsy
Radial nerve palsy can be divided into high and low injuries. A high radial nerve palsy involves the radial nerve proper whereas the low palsy involves only the posterior interosseous nerve (PIN) (both of these are near the level of the elbow).
The importance in the difference in high and low high and low radial nerve palsies is in the presence or absence of active wrist extension. The radial nerve proper will innervate the brachioradialis (BR), extensor carpi radialis longus, and brevis (ECRL and ECRB) prior to dividing into the PIN and the radial sensory nerve and thus, a patient with a high radial nerve palsy will lack wrist extension, thumb extension, and digital extension.
With radial nerve injuries, three functions are lost and must be replaced:
Thumb extension
Finger extension
In high nerve palsies, wrist extension
A. Low Radial Nerve Transfers
Thumb extension | PL-EPL |
Digital extension | Brand—FCR-EDC |
Jones—FCU-EDC | |
Modified Boyes—FDS ring-EDC |
Each of these transfers for digital extension can be used successfully. The disadvantage of the flexor carpi ulnaris (FCU) transfer lies in sacrificing the strongest wrist flexor and its importance in hammering or the “dart throwing” motion. The disadvantage in the FDS ring transfer is the lack of synergism and although EDC excursion is best replicated by the FDS transfer, it is more difficult for the patient to retrain a muscle traditionally used for digital flexion to provide digital extension.
II. Median Nerve Palsy
Low median nerve transfers
The functional deficit resulting from low median nerve palsy is the loss of palmar abduction of the thumb. Therefore, tendon transfers for low median nerve palsies
are transfers to a muscle along the course of the ABP muscle (roughly), the plane between the pisiform and the MP joint of the thumb. Transfers distal to the pisiform allow more thumb flexion and better opposition. Transfers proximal to the pisiform allow more thumb abduction so that the patient can move the thumb out of the plane of the palm, but do not provide pronation necessary for opposition.
There are four transfers typically used for low median nerve palsies:
FDS ring, extensor indicis proprius (EIP), palmaris longus (PL), and Abductor digiti minimi (ADM). The tendon to be transferred is inserted near the level of the MP joint of the thumb, typically along the radial aspect near the site of the insertion of the abductor pollicis brevis (APB), but other sites have been described.
Opposition/abduction
FDS ring (Riordan). This transfer requires the creation of a pulley to recreate the direction of the ABP. This is typically in the region of the pisiform, either by creation of a hole in the palmar fascia or with a distally based loop of the FCU.
EIP (Burkhalter). This transfer is completed by routing the EIP around the ulnar aspect of the forearm and inserting the tendon at the insertion of the APB. Distal harvest of the EIP is undertaken to assure the surgeon of adequate length.
Palmaris longus (Camitz). This transfer functions as an abductor transfer rather than a true opposition transfer. It is most commonly used in patients with long standing carpal tunnel syndrome who have difficulty moving the thumb out of the plane of the palm. The palmaris longus is harvested with a distal extension to include a strip of palmar fascia and transposed through a subcutaneous tunnel to the insertion of the APB.
ADM (Huber). This transfer is most commonly used for reconstruction in congenital thumb hypoplasia. The muscle is detached from the insertion on the small finger proximal phalanx and turned on itself to insert at the level of the APB.
High median nerve transfers
In addition to the loss of thumb opposition, patients with high median nerve palsies lack thumb, index, and middle finger flexion due to paralysis of the FPL and flexor digitorum profundus (FDP) to the index and middle fingers.
Thumb flexion BR-FPL
Index/middle finger flexion. FDP (ring and small)-FDP (index and middle) side-to -side transfer
III. Ulnar Nerve Palsy
Low ulnar nerve palsies. The ulnar nerve innervates the majority of the intrinsic muscles in the hand. Loss of ulnar nerve function in the hand causes loss of power pinch (Jeanne and Froment signs), digital clawing, asynchronous digital flexion, and persistent abduction of the small finger at the MCP joint (Wartenberg sign).
Power pinch is a result of contraction of the adductor pollicis and the first dorsal interosseous, allowing the thumb to contract against the stabilized index finger. With loss of the ulnar-innervated intrinsics, the MP and interphalangeal (IP) joints are controlled by the extrinsic flexors and extensors.
The extensor pollicis longus (EPL) normally functions as a secondary adductor of the thumb, but now becomes the only thumb adductor. Pinch is achieved with contraction volar to the axis of rotation of the MCR joint in order to stabilise the MCP joint. The FPL moment at the IP joint then exceeds the EPL moment at the IP joint, resulting in IP joint flexion FPL (Froment sign).
Clawing. Flexion begins with the intrinsic muscles’ initiation of MP joint flexion, followed by DIP and PIP flexion due to the combined action of the extrinsic flexors (FDS and FDP). When the intrinsic muscles become paralyzed, clawing (MP extension with PIP flexion) occurs due to the contraction of the extrinsic digital flexor and extensor muscles without the balancing force of the intrinsics. The extrinsic extensors cause extension at the MP joint while the extrinsic flexors cause flexion at the DIP and PIP joints. In low ulnar palsy, clawing is seen in the ring and small finger since the lumbricals to the index and middle finger are innervated by the median nerve. For clawing to be present, the FDP must cause active PIP and DIP flexion, and is therefore substantially diminished in the ring and small fingers in high ulnar nerve palsy.
Wartenberg sign. Paralysis of the third volar interossei combined with the abduction force of the PIN innervated extensor digiti minimi (EDM) causes an abduction of the small finger known as Wartenberg sign.
Low ulnar nerve transfers
Transfers for low ulnar nerve palsies are directed at the prevention of clawing, the restoration of power pinch, and restoration of adduction of the small finger.
Power pinch
ECRB with graft to adductor pollicis
The ECRB is detached from its insertion and pulled proximal to the extensor retinaculum. It is extended with a graft, passed between the index and middle metacarpals and then passed subcutaneously to insert into the ulnar aspect of the base of the proximal phalanx of the thumb. This transfer benefits from the synergy between wrist extension and active pinch, making it straightforward for the patient to learn to activate the transfer.
FDS ring to adductor pollicis
The FDS is transferred subcutaneously to the adductor pollicis, using the palmar fascia as a pulley. This transfer is not synergistic, as pinch will occur with wrist flexion rather than extension, so it is not as intuitive as the ECRB transfer and requires more training to use the transfer.
Clawing
FDS ring to lateral bands (proximal phalanx)
The ring finger FDS is transected distally and removed from the flexor sheath, split longitudinally and then inserted into the radial lateral band of the ring and small finger under enough tension to produce MP joint flexion and PIP joint extension. Some surgeons prefer to attach the FDS into the radial aspect of the proximal phalanx to prevent the tendon transfer from stretching out.
Zancolli lasso procedure
This procedure involves harvest of the FDS passing it through a window created between the A1 and A2 pulleys, and suturing it to the A1
pulley, creating a static tenodesis causing a MP joint flexion contracture and allowing PIP joint extension through the extrinsic extensor tendon insertion in the central slip.
ECRB with graft to intrinsics
Brand described transferring the ECRB, with an intercalary graft, to the ring and small fingers for isolated ulnar nerve palsies or to all four fingers in combined low median and ulnar nerve palsies. The tendon is transected at its insertion and pulled proximal to the extensor retinaculum. It is extended with a two-tailed graft, passed dorsal to the retinaculum, through the intermetacarpal space and palmar to the deep intervolar plate ligament (through the lumbrical canal) to insert into the lateral bands of the ring and small fingers.
Correction of Wartenberg deformity
This can be accomplished be transferring the ulnar slip of the EDM to the radial aspect of the MP joint and inserting it into the radial collateral ligament.
High ulnar nerve palsy
The primary difference between the high and low ulnar nerve palsies lies in the loss of function of the ulnar 2 slips of the FDP in the high palsy. This lack of extrinsic flexion mitigates against clawing. Transfers for high ulnar nerve palsies are directed at the restoration of power pinch and flexion of the ring and small fingers. Subsequent transfers to prevent clawing may be necessary.
Power pinch
This transfer is the ECRB with graft as previously described. The use of the ring FDS in contraindicated due to absence of the ring finger FDP.
Digital flexion
Ring and small finger flexion is obtained by transferring the ring/small to the index/middle FDP in a side-to-side fashion. This is the same principle that is used in high median nerve injuries where the two functioning FDP tendons are used to power the two paralyzed muscles.
IV. Combined Median and Ulnar Nerve Palsies
Motors for transfer are limited to muscles innervated by the radial nerve.
A. Combined Low Median and Ulnar Nerve Transfers
Thumb adduction is typically achieved by ECRB to adductor pollicis with a graft as described for low ulnar nerve palsies. Thumb opposition is achieved with EIP around the ulnar aspect of the wrist as described for low median nerve palsies. Clawing is prevented by transferring the FDS from the middle to the index and middle lateral bands and the FDS from the ring to the ring and small lateral bands.
B. Combined High Median and Ulnar Nerve Transfers
In addition to the pinch, opposition and clawing transfers used for low combined median and ulnar nerve palsies, the ECRL is transferred to all four FDP tendons to restore digital flexion and BR to FPL for thumb flexion. Preservation of wrist motion to assist with grasp and pinch through tenodesis will greatly improve function.
V. Musculocutaneous Nerve Palsies
The functional loss from this injury is elbow flexion. As experience with nerve transfers continues to improve (Oberlin transfer and MacKinnon double fascicular transfer), the number of patients requiring tendon transfer to restore elbow flexion will decrease. Patients who can benefit from these transfers include those who have had failed nerve repair or reconstruction, those in whom an excessive period of time has elapsed between injury and presentation, and those with irreparable plexus injuries wherein sources of nerve grafts or nerve transfers are not available.
A. Pectoralis Major Transfer
The pectoralis major has a dual innervation. The lateral pectoral nerve is derived from the lateral cord of the brachial plexus (C5, C6, and C7) and supplies the clavicular portion of the muscle. The medial pectoral nerve arises from the medial cord, containing fibers from C8 and T1 and is spared in upper trunk brachial plexus lesions. The medial pectoral nerve supplies the sternocostal portion of the muscle and this portion can be used to restore elbow flexion. The muscle can be detached from its insertion on the humerus and the distal aspect of the muscle is transferred to the biceps tendon. Elongation with a fascia lata autograft is necessary. Alternatively, the humeral insertion can be transferred to coracoid process of the scapula. This is a technically demanding procedure and the postoperative appearance is bothersome to some patients, but does produce good strength and leaves minimal functional deficit.
B. Latissimus Dorsi Transfer
The latissimus is innervated from the thoracodorsal nerve, from the posterior cord (C6, C7, and C8). Similar to the pectoralis major transfer, the latissimus can be transferred by leaving the origin on the humerus intact, but generally it is transfered anteriorly to the coracoid process of the clavicle or the acromion, creating a vector similar to that of the biceps. The distal aspect of the muscle is transferred to the distal biceps tendon. Although this is technically more difficult, the aesthetic results are superior to the pectoralis major transfer. It can be transferred with a skin paddle to allow for the bulk of the muscle and it still provides strong elbow flexion.
C. Steindler Flexorplasty
This procedure involves transfer of the origin of the flexor pronator mass (innervated by the median nerve) proximally 5 cm, and affixing it to the anterior humeral shaft.
D. Triceps Transfer
This procedure may involve the sacrifice of elbow extension strength for elbow flexion, allowing gravity to assist in elbow extension. The triceps is detached distally and transferred around the lateral aspect of the humerus and secured to the distal biceps tendon. This procedure is not routinely used due to loss of active elbow extension.
VI. Axillary Nerve Palsies
Axillary nerve palsies, similar to musculocutaneous nerve palsies, typically result from upper trunk brachial plexus injuries rather than isolated nerve injuries and paralysis of the deltoid and rotator cuff from axillary nerve injury often accompanies paralysis or
weakness of elbow flexion. The problems resulting from axillary nerve injury include lack of external rotation and abduction of the shoulder. External rotation is required to bring the hand above the level of shoulder and reach the mouth. The intact internal rotators of the shoulder (pectoralis major and latisssimus dorsi) cause the humerus to rotate internally to the chest. When elbow flexion is restored, the humerus will be displaced proximally if the shoulder is not stable. The goals of the tendon transfers for axillary nerve palsies are to stabilize the shoulder by restoring muscle balance. Alternatively, shoulder stability can be obtained from arthrodesis. The transfer most commonly used for shoulder stability is the latissimus dorsi, either alone or with the teres major.
weakness of elbow flexion. The problems resulting from axillary nerve injury include lack of external rotation and abduction of the shoulder. External rotation is required to bring the hand above the level of shoulder and reach the mouth. The intact internal rotators of the shoulder (pectoralis major and latisssimus dorsi) cause the humerus to rotate internally to the chest. When elbow flexion is restored, the humerus will be displaced proximally if the shoulder is not stable. The goals of the tendon transfers for axillary nerve palsies are to stabilize the shoulder by restoring muscle balance. Alternatively, shoulder stability can be obtained from arthrodesis. The transfer most commonly used for shoulder stability is the latissimus dorsi, either alone or with the teres major.
L’Episcipo Procedure
The tendons of insertion on the latissimus dorsi and the teres major are transferred posteriolaterally on the humerus, converting internal rotators to external rotators. The shoulder must have passive external rotation for this to be successful, so if a contracture of the shoulder joint is present, it must be released simultaneously. In addition, a rotational osteotomy of the proximal humerus can improve arm position.
Cerebral Palsy
I. Introduction
Cerebral palsy is a central nervous system (CNS) insult causing an upper motor neuron injury; the normal inhibitory control of tone is lost and the resultant peripheral manifestation is spasticity. Muscle spasticity causes muscle imbalance across joints with resultant loss of function. With growth, secondary skeletal changes can occur as well.
Cerebral palsy has the added complexity that the CNS injury occurs in the perinatal period so that the effect of spasticity on the immature skeleton must be considered as well.
In the upper extremity, the typical pattern of spastic joint deformities includes shoulder internal rotation, elbow flexion, forearm pronation, wrist flexion and ulnar deviation, thumb-in-palm and finger swan neck or clenched fist deformities.
Although this pattern of deformity is the most common, the particular pattern and severity are specific for each patient based on the extent and area of the underlying CNS disorder.
Motor involvement can take the form of spasticity (increased tone), flaccidity (decreased tone), or athetosis (lack of or poor control of tone).
II. Patient Evaluation
Assessment of the patient with spastic cerebral palsy starts with the history and physical examination.
Because cerebral palsy is associated with low birth weight and prematurity, associated medical problems should be noted, particularly seizures and mental retardation as indicators of more global CNS involvement.
Physical examination for passive range of motion of the shoulder, elbow, forearm, wrist, and hand is performed to evaluate for joint and/or contractures.
Passive range of motion needs to be done slowly to overcome muscle spasticity with gentle sustained resistance.
Active range of motion is assessed next, including specific muscle testing for voluntary motor control of antagonist muscles. This is particularly important for muscles that are considered for tendon transfer such as the pronator teres (for PT re-routing); the FCU, extensor carpi ulnaris (ECU), or the BR (for wrist extension); the extensor pollicus longus (for EPL re-routing); and the extensor pollicis brevis (EPB) and abductor pollicis longus for control of antagonists to the thumb-in-palm deformity.Related posts:
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