Tendon Transfers for Median, Radial, and Ulnar Nerve Palsy

Acknowledgment: This chapter is based on the chapters in previous editions of Green’s Operative Hand Surgery, which were written by George Anderson, William Burkhalter, David Green, John Ingari, and George Omer, as well as Nicholas Barton, who was my coauthor for the fourth edition. My tendon transfer experience cannot match that of these previous authors, and my thoughts and views on tendon transfer surgery have been molded by reading the previous editions’ chapters, as well as by revisiting all the research articles these authors wrote and cited. The previous authors of these chapters have therefore been my teachers and mentors, and I am indebted to their labors.

Damage to one of the three main nerves of the upper extremity causes loss of function due to paralysis of muscles and loss of sensation. Tendon transfers can be used to re-create the functions of some of the paralyzed muscles but cannot restore normal strength and coordination. Loss of function due to loss of sensation cannot be restored by tendon transfers but is often well accommodated by the eyes. This accommodation is lost when the eyes cannot see the hand such as in darkness or when the hand is in a pocket or bag searching for an object. The loss of sensation after radial nerve injury is minimal and does not involve critical areas of the hand, whereas the loss of motor function is major and significantly impacts function. Thus tendon transfers to restore radial nerve motor function have the potential to greatly improve hand function and the patient’s well-being and ability to pursue a “normal” life. In contrast, the loss of sensation after a median nerve injury involves the most critical areas of the hand, and absent or poor sensation or dysesthesia will reduce the potential benefit of tendon transfers to restore lost motor function.

Every surgeon will have her or his own indications for tendon transfer surgery and favorite transfers, which are based on experience and the teaching of their mentors. This is as comparative studies of different transfers in specific situations are rare. Thus transfers favored by some surgeons will not be favored by others. Perhaps the only universally accepted “best” transfer to restore a specific function is transfer of pronator teres (PT) to extensor carpi radialis brevis (ECRB) to restore wrist extension.

Principles of Tendon Transfer Surgery

The principles of tendon transfer surgery are frequently reiterated but often forgotten. They were established by surgeons such as Mayer and Bunnell and must be adhered to regardless of whether the transfers are to restore median, radial, or ulnar nerve motor function.

Prevention and Correction of Contracture

A passive, fluid range of joint movement, which is sufficient to improve hand function, must be present before a tendon transfer can be performed. This is because no tendon transfer can move a stiff joint, and it is impossible for a joint to have a greater range of active motion postoperatively than its preoperative range of passive movement. Soft tissue and joint contractures are easier to prevent than to correct, so it is imperative that all joints are kept supple after any nerve injury, particularly those with surrounding soft tissue injuries.

Tissue Equilibrium

The timing of tendon transfers is controversial, but all authors agree that no transfer should be done until the local tissues are in optimal condition. Steindler’s expression, “tissue equilibrium,” implies that soft tissue induration has resolved, the wounds have matured, the joints are supple, and the scars are as soft as they are likely to become. Performing tendon transfers, or any elective operation, before tissue equilibrium has been reached is to invite disaster. If scar tissue remains after maximum recovery has been achieved, then the surgeon must consider providing new skin coverage with flaps before transfer. Alternatively, she or he must use transfers that avoid the scarred areas. Tendon transfers work best when passed between the subcutaneous fat and deep fascial layer and are unlikely to work at all in a scar pathway. Brand emphasized the concept of gentle tunneling using a blunt-tipped instrument and probing natural tissue planes to find the path of least resistance. When performing tendon transfers, the surgeon should minimize the likelihood of new scar formation, and skin incisions should be planned so that tendon junctures do not lie directly underneath them.

Adequate Strength

The muscle chosen as the donor for transfer must be sufficiently strong to perform its new function in its altered position. The relative strengths (and excursions) of the donor muscle, as well as the muscles whose function they will replace, should be as well matched as possible ( Table 31.1 ). The work capacity of a muscle is related to its volume.

TABLE 31.1

Resting Muscle-Fiber Lengths and Tension Fractions of Muscles With Functions Commonly Restored With Tendon Transfers and Potential Transfer Motors

From Brand PW, Beach RB, Thompson DE. Relative tension and potential excursion of muscles in the forearm and hand. J Hand Surg . 1981;6(3):209–219.

	Resting Muscle-Fiber Length (cm)	Tension Fraction (%)
Radial Nerve Palsy
Brachioradialis	16.1 (10.9–21.3)	2.4
Extensor carpi radialis brevis ^a	6.1	4.2
Extensor carpi radialis longus	9.3	3.5
Extensor carpi ulnaris	4.5	4.5
Extensor digitorum communis ^a	5.5–6.0	0.9–1.7
Extensor indicis proprius	5.5	1.0
Extensor digiti minimi	5.9	1.0
Extensor pollicis longus ^a	5.7	1.3
Extensor pollicis brevis	4.3	0.8
Abductor pollicis longus	4.6	3.1
Median
Intrinsic (Paralyzed in Low and High Palsy)
Abductor pollicis brevis ^a	3.7	1.1
Flexor pollicis brevis ^a	3.6	1.3
Opponens pollicis ^a	2.4	1.9
*Extrinsic (Paralyzed in High Palsy)*
Pronator teres	5.1	5.5
Palmaris longus	5.0	1.2
Flexor carpi radialis ^a	5.2	4.1
Flexor pollicis longus ^a	5.9	2.7
Flexor digitorum profundus, index ^a	6.6	2.7
Flexor digitorum profundus, middle ^a	6.6	3.4
Flexor digitorum superficialis, middle	7.0	3.4
Flexor digitorum superficialis, ring	7.3	3.0
Ulnar
Intrinsic (Paralyzed in Low and High Palsy)
Adductor pollicis brevis ^a	3.6	3.0
First dorsal interosseous ^a	2.5	3.2
Second and fourth dorsal interossei (combined) ^a	1.5	6.2
First and third palmar interossei (combined) ^a	1.6	3.5
Abductor digiti minimi ^a	4.0	1.4
Ring and little finger lumbricals (combined)	5.5	0.2
Extrinsic (Paralyzed in High Palsy)
Flexor carpi ulnaris	4.2	6.7
Flexor digitorum profundus (ring)	6.8	3.0
Flexor digitorum profundus (little)	6.2	2.8

a Muscles with functions that are commonly restored with tendon transfers.

Transfer of a muscle to replace the function of another inevitably weakens it, typically by one grade on the rather imprecise Medical Research Council (MRC) grading system. ^, Thus, muscles that have been previously denervated, but have regained function, should only be used if they have regained near-normal strength.

Amplitude of Motion

The surgeon must have an appreciation of the amplitude of tendon excursion for each muscle. This is proportional to the length of its individual muscle fibers (see Table 31.1 ). ^, Lieber and colleagues have assessed muscle characteristics with intraoperative laser diffraction; however, this technique is not widely used and is complex. ^, Boyes suggested the use of the following values for practical purposes.

Wrist flexors and extensors have excursion amplitudes of approximately 33 mm, whereas the finger extensors and extensor pollicis longus (EPL) have 50 mm and the finger flexors have 70 mm excursions, respectively. Thus a wrist flexor cannot be expected to restore the full range of active motion provided by a finger extensor, the function of which it is replacing. However, the range of active finger motion provided by a wrist flexor can be augmented through the tenodesis effect of active flexion and extension of the wrist. Thus following radial nerve transfers, wrist extension reduces tension in a flexor carpi radialis (FCR) to extensor digitorum communis (EDC) transfer and allows finger flexors to produce greater finger flexion. In contrast, wrist flexion increases tension in this transfer and allows it to produce increased “active” finger extension. This tenodesis effect explains the adage that the wrist should never, if at all possible, be fused in a person requiring tendon transfers. Excursion amplitude can also be increased by extensive dissection of the muscle from its surrounding fascial attachments. This is particularly true of the brachioradialis (BR).

Straight Line of Pull

The transfer must run in a straight line from its own origin to the insertion of the tendon it is to drive. If a tendon transfer does not run in a straight line, increased force needs to be expended to overcome friction with the surrounding soft tissues, and the transfer will try to migrate so that it does run in a straight line. In doing so, the transfer will lose tension and become lax and less efficient or totally ineffective. Sometimes it is not possible for the transfer to run in a straight line, for example, in an extensor indicis proprius (EIP) or flexor digitorum superficialis (FDS) opponensplasty. In this situation a robust pulley is required, around which the transfer can change direction. The pulley must not be able to migrate over time because this would result in reduced tension and loss of, or restricted, function. The transfer must run in a straight line from its origin to the pulley and from the pulley to the insertion of the tendon it is to drive; in addition, the angular change in direction of the transfer at the pulley should be as small as possible to minimize friction and adhesion formation.

One Tendon–One Function

A single transferred tendon cannot be expected to perform two dissimilar active actions. If a transfer has two insertions that perform dissimilar active functions, it will act predominantly on the tighter insertion. However, one transfer can be attached to multiple tendons that all have similar functions. Thus the FCR can be attached to the EDC tendons of all four fingers (and, if necessary, the EPL) to actively extend them simultaneously, but not individually. Also the extensor carpi radialis longus (ECRL) tendon can be attached to a lateral band of the extensor apparatus of each finger to restore intrinsic function in all four fingers. A tendon transfer can also restore one active function and provide an additional and different passive function. For example, an opponensplasty can be attached in series, first to the insertion of abductor pollicis brevis (APB) and then to extensor mechanism of the thumb: (1) The initial attachment is to restore active opposition, and (2) the second is to passively restrict flexion of the thumb interphalangeal (IP) joint, which is sometimes a problem in combined median and ulnar nerve palsies.

Synergism

Synergy of activity of the donor and “recipient” muscles and/or tendons is generally considered advantageous, and synergistic transfers should be selected if at all possible. However, Omer and Brand both believe that any transfer can be reeducated to fulfill its new function, especially in children, provided the restored function is of benefit to the patient.

Wrist extension usually occurs with finger flexion, and both sets of muscles are activated concurrently by the brain when gripping. On this premise, it is argued that patients find it easiest to train a wrist flexor to restore finger extension. A possible exception to this rule is the use of the superficialis (sublimis) tendons, which have more independent cortical control than other muscles in the hand.

Expendable Donor

Transfer of a musculotendinous unit must not result in unacceptable loss of function. Thus there should always be at least one other musculotendinous unit providing the same function as the one being transferred so that the original function of the transfer is not completely lost. One should not transfer both the ECRL and ECRB to restore new functions because active wrist extension would be lost. The same is true for FCR and flexor carpi ulnaris (FCU).

An additional well-known guideline is suggested, that is, the paralyzed “recipient” muscle/tendon, whose function is to be replaced by a transfer, should not be divided to allow the transfer to be attached end-to-end unless there is no prospect of spontaneous recovery of the muscle. If there is any prospect of recovery, then an end-to-side attachment is preferred.

Critical Points

Tendon Transfer

An elective tendon transfer should never be performed in the presence of unhealed wounds.
Optimal and useful passive joint motion must be restored before tendon transfer.
The transfer must not pass through areas of scar tissue or under skin grafts, and surgical incisions should not be placed directly over the transfer.
Whenever possible, cutaneous sensibility should be restored before tendon transfer.
The normal function of the transferred muscle must be expendable.
The transferred muscle must be under voluntary control and must have an independent action.
Transferred muscle must have sufficient amplitude and power to perform its new function; thus reinnervated muscles should be used only if fully recovered.
If the transfer cannot perform its new function with a straight line of pull from its origin to its insertion, it should pass through no more than one pulley. Acute angulation of the transfer at the pulley should be avoided.
Synergism between the muscle’s original and new actions facilitates rehabilitation.

Median Nerve Palsy

The aim of reconstructive surgery in median nerve palsy is to restore lost motor function, in particular, thumb opposition, flexor pollicis longus (FPL), and index finger profundus function. Attempts to restore sensibility in the hand, specifically to the thumb tip, with neurovascular island skin flaps generally have been abandoned, but sensory nerve transfer is possible. ^, The benefits of reconstructive surgery are, to a large extent, determined by the quality of hand sensation, contralateral hand function, and the patient’s motivation and ability to adapt to any sensory loss.

Median nerve injuries are classified as “high” or “low” depending on whether the lesion is proximal or distal to the origin of the anterior interosseous nerve in the proximal forearm. In low injuries, the thenar intrinsic muscles innervated by the median nerve, usually the APB, opponens pollicis, and superficial head of the flexor pollicis brevis (FPB), are paralyzed. In high injuries, the PT, the FCR, all the finger superficiales, the index and middle finger profundi, the FPL, and the pronator quadratus muscles are also paralyzed.

Low Median Nerve Palsy

Polio was the predominant cause of thenar muscle intrinsic paralysis in the first half of the 20th century. Because this disease causes a pure motor deficit, it provides an ideal indication for opponensplasty. The two world wars also produced a large number of median nerve injuries that were frequently complex and occurred in conjunction with other nerve and severe soft tissue injuries. The present indications for restoration of thumb opposition include compressive and traumatic disruptions of the median nerve; leprosy; neurologic diseases (e.g., Charcot-Marie-Tooth disease, monomelic amyotrophy), spinal muscular atrophy, and syringomyelia; and congenital absence of the thenar muscles.

Biomechanics of Thumb Opposition

Thumb opposition is a complex movement requiring trapeziometacarpal joint abduction, flexion, and pronation. Retroposition, the opposite movement, is a combination of trapeziometacarpal joint adduction, extension, and supination. Axial thumb rotation during opposition and retroposition, usually 90 degrees of pronation and 60 degrees of supination, respectively, occurs on the spheroid area of the saddle-shaped trapezial articular surface. Pronation is probably an obligatory passive movement that occurs during circumduction toward the palm as a result of the force-couple produced by thumb intrinsic muscle contraction and passive tension within the dorsal trapeziometacarpal ligament. Retroposition probably also occurs passively during thumb extension as a result of the force-couple produced by contraction of the EPL and the extensor pollicis brevis (EPB) and the abductor pollicis longus (APL) muscles and passive tension within the radiopalmar (anterior oblique) ligament. Although the force-couples may be the prime mechanism of axial rotation, other mechanisms must exist inasmuch as thumb pronation is preserved after trapeziectomy.

The prime muscle of thumb opposition is the APB, although both the opponens pollicis and FPB also produce some opposition. The adductor pollicis (AP) and the two extrinsic thumb extensors cause thumb retroposition, whereas the FPL can act as a muscle of either opposition or retroposition, depending on the position of the thumb.

The classic description of thumb intrinsic muscle innervation is that the APB, the opponens pollicis, and the FPB are supplied by the motor branch of the median nerve, whereas the AP is supplied by the deep branch of the ulnar nerve. However, there is considerable diversity in the pattern of innervation, and clinical studies suggest that all the thenar muscles are innervated, in part at least, by either the ulnar (2%) or the median (2%) nerve in a few instances. Furthermore, the FPB remains functional in 73% of complete median and 58% of complete ulnar nerve injuries, thus demonstrating that this muscle frequently has a dual median and ulnar innervation. Anatomic dissection suggests that the median nerve supplies the APB, the opponens pollicis, and the superficial head of the FPB in 63% of hands, but only the APB and the opponens pollicis in 30% of hands.

Zancolli and Cozzi believe that the superficial head of the FPB has dual median and ulnar innervation in 30% of hands, whereas its deep head has dual innervation in 79% of cases but is exclusively supplied by the ulnar nerve in 19%. They also believe that the oblique head of the AP has dual ulnar and median innervation in 35% of cases, whereas its transverse head is practically always (96%) innervated by the ulnar nerve. Although some of these findings are contradictory, the variability of thenar muscle innervation explains why thumb abduction and opposition are frequently retained after complete median nerve injuries. ^,

The Deficit and the Deformity

Thumb abduction and opposition are frequently retained after isolated median nerve injury as a result of preserved ulnar nerve function. Jensen believed that opponensplasty was required in only 14% of median nerve injuries, and it is my experience that reasonable opposition is commonly retained in complete median nerve transections. Furthermore, I find that satisfactory thumb opposition is usually retained in severe carpal tunnel syndrome, even in the presence of significant thenar wasting. Foucher and colleagues found only 7% of the patients with severe carpal tunnel syndrome had absent or inadequate thumb opposition. All the thenar intrinsic muscles are paralyzed after combined median and ulnar nerve injuries; in this situation, thumb opposition is absent and the patient is only able to flex the thumb across the palm by using the FPL. In combined ulnar and high median nerve injuries, resting thumb posture tends to be extended and supinated by the unopposed extrinsic extensor muscles.

Tendon Transfers to Restore Thumb Opposition

History

Steindler is credited with performing the first opponensplasty in 1917. He attached a radial slip of the FPL tendon onto the dorsum at the base of the thumb’s proximal phalanx. Shortly afterward, Cook used the extensor digiti minimi (EDM) for an opponensplasty and Ney attached either the palmaris longus (PL) or FCR to the EPB tendon, which was rerouted through the carpal tunnel. Huber in 1921 and Nicolaysen in 1922 described ADM opponensplasty.

Bunnell in 1924 and Camitz in 1929 both reported that the PL tendon could be satisfactorily elongated with a strip of palmar aponeurosis so that it could be used in an opponensplasty without the need for a tendon graft. To maximize thumb opposition, Bunnell recommended passing the transferred tendon through a pulley on the ulnar border of the wrist so that it ran subcutaneously across the palm to its thumb insertion. ^, Thompson used the ulnar border of the palmar aponeurosis as a pulley for Royle’s superficialis transfer. A limitation of both the palmaris and superficialis transfers is that they are useful only for low median nerve palsies. Aguirre and Caplan, in 1956, first described EIP opponensplasty, which can be used for both high and low median nerve palsies and does not require manufacture of a pulley or a tendon graft.

Patient counseling

Although the indication for an opponensplasty is loss of opposition, the need for surgery is loss of function due to loss of opposition. If loss of opposition is unilateral, especially if it affects the nondominant hand, then the consequent loss of function may be minimal and insufficient to warrant surgery. Additionally, if there is also loss of or absent sensation in the median nerve territory, this may reduce any potential benefit of an opponensplasty because the loss of function is primarily due to the loss of sensation. Careful patient counseling about the possible functional benefit, the rehabilitation process, and the likely outcome of surgery (this may be somewhat less than the published success rates for restoration of opposition movement) is mandatory. The surgeon must have a clear picture of the functional disability and be confident that this is due to the loss of opposition and not to other factors (e.g., sensory impairment or joint stiffness).

General principles of tendon transfer with reference to opponensplasty

Prevention and preoperative treatment of contractures

With median nerve palsy and complete intrinsic paralysis, the thumb may adopt a supinated and adducted position, and a first web space contracture can develop. This is readily prevented by passive thumb abduction and opposition exercises, supplemented by abduction splints as needed. Temporary internal splintage of the thumb metacarpal in abduction with a Kirschner wire may be indicated when there is an associated acute severe thenar or first web space soft tissue injury and thus a high risk of first web space contracture.

Established soft tissue contractures must be corrected either before or during opponensplasty because no opponensplasty has sufficient strength to improve a preoperative passive loss of opposition. Failure to detect and correct contractures preoperatively is a common cause of failure. First web space contractures are generally due to contractures of the skin and deep fascia on its extensor surface and usually can be readily detected. However, contracture of the dorsal capsule of the trapeziometacarpal joint, which restricts opposition but permits abduction, is detected only by careful clinical examination. If supervised physiotherapy and splintage fail to correct a contracture, surgical release is indicated.

In the absence of any injury to the thenar muscles or the base of the thumb, first web contractures usually can be released satisfactorily through a dorsal web space incision. The fascia over the AP and the first dorsal interosseous muscles is released and the dorsal web space skin widened with a skin graft or flap. ^, Isolated capsular contractures of the trapeziometacarpal joint should be released through a small incision over the base of this joint. In severe contractures, both rotational osteotomy at the base of the thumb metacarpal and trapeziectomy have been recommended. An osteotomy modifies rather than improves the range of thumb movement. For a more comprehensive discussion of thumb web contractures, see Chapter 48 .

Selection of motor for transfer

The normal function of the muscle selected for opponensplasty must be expendable, and it should have strength and potential for excursion similar to that of the APB and opponens pollicis muscles, the functions of which it is to replace. The ideal opponensplasty motor should have a tension fraction similar to that of the combined APB and opponens pollicis tension (1.1 + 1.9 = 3.0) and a muscle-fiber length that is at least as long as that of the APB (see Table 31.1 ). The greater the potential for excursion of the transfer, the greater the margin of error when setting the transfer’s tension.

It is also advantageous to select a motor with a tendon that is long enough to reach the thumb metacarpophalangeal (MCP) joint, thus avoiding the need for a tendon graft. This makes the operation less complicated and reduces the likelihood of troublesome adhesions. Finally, rehabilitation is simpler if the selected motor acts synergistically with the APB.

Pulley design

Because true thumb opposition is restored best by transfers that run subcutaneously across the palm, parallel to the APB muscle, all extrinsic opponensplasties should pass around a stout fixed pulley in the region of the pisiform on the ulnar border of the wrist. It is important that a pulley is strong and generates minimal soft tissue resistance. Opponens transfers from the forearm extensor compartment generally use the distal ulna as the pulley, and most of these transfers are simply passed through a wide subcutaneous tunnel on the ulnar border of the distal forearm. Alternatively, some extensor muscle opponensplasties pass through and use a window in the interosseous membrane as the pulley, in which case it is important to make a very large window.

The Camitz procedure does not classically employ a pulley and thus is less effective in providing true opposition. If a forearm flexor compartment muscle is used for opponensplasty, a pulley has to be manufactured on the ulnar border of the wrist. Numerous designs have been described, and these are discussed later in the chapter in the Superficialis Transfers section.

Opponensplasty insertions

Many insertions have been described ( Fig. 31.1 ), and these can be broadly divided into single- and dual-insertion techniques. Dual insertion aims to allow the tendon transfer to perform two functions, usually active opposition and either passive stabilization of the MCP joint or restriction of IP joint flexion, both of which are beneficial in combined median and ulnar nerve palsies. Bunnell recommended (and others used) a drill hole in the dorsoulnar aspect at the base of the thumb proximal phalanx as the opponensplasty insertion point to produce thumb pronation as well as abduction. However, pronation occurs passively when the thumb is abducted and flexed, and biomechanical studies suggest that attaching the opponensplasty to the APB insertion on the radial aspect of the thumb MCP joint produces at least as good an opposition as the Bunnell and other commonly used insertions. Thus, the APB insertion is now widely used in isolated median nerve palsies.

Dual insertions into the APB insertion and either the dorsal MCP joint capsule or the thumb extensor expansion ^, are probably unnecessary in isolated median nerve palsy, although they may be useful in a completely intrinsic-minus thumb. Use of the EPB tendon and its insertion is reserved for complex cases when the extensor carpi ulnaris (ECU) is selected as the opponensplasty motor.

Results

The majority of papers on opponensplasty report a high percentage of excellent and good results and attribute most failures to persistent contractures or technical problems. There is no universally accepted method of classifying the results of opponensplasty, but recent papers are probably more stringent than earlier articles in their assessment of outcomes. Unfortunately, it is impossible to compare the results and complication rates of different opponensplasties because of multiple variables, including: (1) the underlying disease process (e.g., polio, leprosy, nerve injury), (2) the neurologic deficit (e.g., low median, high median, or combined median and ulnar), (3) the sensory defect, and (4) the potential for spontaneous recovery. For example, if transfers are performed early when there is still potential for recovery, restoration of excellent opposition may be incorrectly attributed to the opponensplasty instead of nerve regeneration. Sixty-six percent of the patients regain or never lose good opposition after median nerve repair, and loss of thenar muscle function frequently recovers after carpal tunnel release. ^,

Many papers classify an excellent result as one in which physically powerful opposition with full mobility is restored. A fair result is one with either full but weak opposition or limited but strong opposition. Sundararaj and Mani graded their results in leprosy according to the range of opposition and the position of the thumb IP joint ( Table 31.2 ). In contrast, Foucher and colleagues objectively measured active thumb abduction, opposition, and rotation occurring on movement of the thumb from full active retroposition to opposition.

TABLE 31.2

Two Methods of Assessment of Opponensplasty Surgery

Sundararaj and Mani, 1984		Jacobs and Thompson, 1960 ^a
Excellent	Opposition to ring or little fingertip with IP joint extended	75% of function of opposite thumb when normal or <20 degrees of difference between the planes of the opposed thumbnail and the palm with good power
Good	Opposition to index or middle fingertip with IP joint extended
Fair	Thumb IP joint flexes during opposition	Full, though weak, opposition or restricted, but strong, opposition
		or
Poor	No opposition restored	No opposition restored

a Jacobs and Thompson did not subdivide excellent and good results.

Nevertheless, the surgeon’s objective and the patient’s subjective assessments of outcome are not always in agreement. Although a patient may demonstrate good muscle opposition to the surgeon in the clinic and be believable when saying that the opponensplasty is of functional benefit, the person may not use the newly restored opposition in everyday life. This is especially the case with combined median and ulnar nerve palsies, where the patient frequently finds it easier and faster to hold objects between the sides of the thumb and hand (lateral pinch) by using the EPL to adduct and supinate the thumb ( Fig. 31.2 ).

Critical Points

Management Principles in Opponensplasty

Surgery is needed when loss of opposition causes a meaningful functional deficit for the patient.
The surgeon should adhere to all general principles of tendon transfer.
Established soft tissue contractures must be corrected before or during opponensplasty; careful preoperative evaluation is essential.
The ideal opponensplasty motor should have a tension fraction of around 3.0 and a muscle-fiber length at least as long as the APB.
An appropriate pulley should be chosen to ensure a line of pull that replicates the APB.
Tendon grafts should be avoided.
Rehabilitation is simpler if the selected motor acts synergistically with the APB.
A single insertion of the transferred tendon is all that is needed for most isolated median nerve palsies.

Fig. 31.2, A patient with bilateral T1 neuropathy due to neurologic disease. A, Left hand before extensor indicis proprius (EIP) opponensplasty demonstrating lateral “squeeze” between the retroposed thumb and the side of the index finger. The patient can only pick up objects from a table top with forearm fully pronated. B, Right hand after EIP opponensplasty showing that thumb-to-index pulp pinch is now possible. This allows the patient to pick up objects from flat surfaces without full forearm pronation and allows the person to better see what is being done.

Four standard opponensplasties

There are four widely used, reliable opponensplasties, at least one of which will be appropriate for the vast majority of clinical situations:

1.
FDS opponensplasty
- a.
  Royle-Thompson technique
- b.
  Bunnell technique
2.
EIP opponensplasty
3.
Huber transfer (ADM)
4.
Camitz procedure (PL)

Superficialis opponensplasties

There is no universally accepted “best technique” of superficialis transfer, and a wide variety of different harvest techniques, pulley constructions, and transfer insertions are used, as described in the following subsections. The ring finger superficialis is widely used as the opponensplasty motor. However, because this may weaken power grip, some surgeons prefer to use the middle finger superficialis if it is available. Potential transfer insertions have been discussed earlier in this chapter.

Superficialis tendon harvest

Royle and Thompson both divided the ring finger superficialis tendon at its insertion onto the middle phalanx through a transverse insertion within the basal finger crease. However, it has subsequently been recognized that several superficialis harvest techniques, including division at its insertion, can cause donor digit proximal interphalangeal (PIP) joint flexion contractures or, especially in the supple Asian hand, swan neck and other deformities.

North and Littler suggested that division of the superficialis tendon at its insertion destroys the vincula and disrupts the blood supply to the profundus tendon; furthermore, surgical trauma may create scar tissue within the flexor sheath and PIP joint capsule, thus causing adhesions and/or contracture. They recommended division of the superficialis tendon proximal to its bifurcation through a window between the A1 and A2 pulleys with the finger fully flexed. This avoids injury to the flexor sheath at the level of the PIP joint and leaves behind a 3-cm length of superficialis tendon that glides freely within the flexor sheath. With this technique, 8 of 16 patients experienced no problems in the donor digit and the remainder only lost an average of eight degrees extension of the PIP joint. None experienced any major disability or deformity. Other surgeons have recommended that the distal tags of the donor superficialis tendon be left long and sutured across the palmar plate to reinforce it and prevent hyperextension.

In a study series of 116 superficialis opponensplasties for leprosy, the ring finger superficialis tendon was harvested through either a midlateral approach or a Bruner incision on the flexor surface of the finger. Extension lag at the distal interphalangeal (DIP) joint and fixed-flexion deformities at the PIP joint occurred in 44% and 8% of cases, respectively, when the lateral approach was used but in only 8% and 0% of cases, respectively, when the Bruner incision was used. These authors believed that the high complication rates associated with the lateral approach were due to scar tissue and adhesion formation around the lateral bands of the extensor hood, which are retracted during this exposure. However, in another series of 100 leprosy patients with ulnar, median, or combined nerve palsies, no correlation was found between harvest technique and donor digit morbidity and deformity.

Swan neck deformities and DIP joint extension lags occurred in 15% and 29% of the donor fingers, respectively. The DIP joint extension lags were usually less than 20 degrees, unless associated with a swan neck deformity, in which case they could be as much as 80 degrees. In addition, 26% of the cases in this study developed a fixed-flexion deformity of the PIP joint (50 to 70 degrees), and PIP joint flexion was reduced in 16%. These authors concluded that postoperative deformity in superficialis donor digits is multifactorial and depends on the preoperative condition of the PIP joint, the method of superficialis harvest, the surgeon’s skill, the postoperative rehabilitation regime, the expertise of the therapist, and the patient’s motivation.

Many surgeons believe that division of the superficialis tendon at its insertion increases the risk of swan neck deformity. Furthermore, this technique usually requires an additional palmar incision to split the distal superficialis tendon and free it from the profundus tendon. Because sufficient superficialis tendon length for opponensplasty is provided by harvesting the superficialis tendon through an incision in the distal aspect of the palm, there seems little point in risking a more distal division.

The pulley

Passing the superficialis tendon around the FCU tendon in the distal forearm was a popular and simple pulley design, ^, ^, but this technique has fallen out of favor because the pulley is not fixed and migrates proximally. Thus the transfer gradually adopts an increasingly longitudinal line of action and becomes less efficient with time.

Bunnell described several pulley designs for use with superficialis and other forearm flexor opponensplasties. These included looping a free tendon graft around the FCU tendon and using a strip of the FCU tendon based on its attachment to the pisiform. Although the use of a distally based strip of FCU as a pulley was popular, its raw surface may encourage adhesion formation, and radial migration of this pulley has been observed over a period of years. To prevent this migration, the distally based slip of FCU tendon can be attached to the ECU tendon. The angle between the distal edge of the flexor retinaculum and the ulnar border of the palmar aponeurosis is used effectively as a pulley in the Thompson-Royle transfer, ^, and good opposition is also restored when a window in the flexor retinaculum is used as the pulley. Guyon canal can also be used as a pulley, ^, and although radial migration may occur, this does not necessarily reduce the effectiveness of the opponensplasty.

Biomechanical studies, including those done by Cooney et al. and Lee et al., have shown that the function of an opponensplasty can be modified to an individual patient’s requirements by altering the position of the pulley. Use of the FCU tendon or an FCU loop maximizes palmar abduction, whereas use of a Guyon canal, or the angle created by the distal edge of the flexor retinaculum and the ulnar border of the palmar aponeurosis, produces the closest approximation of the thumb tip to the little finger. In addition, placing the pulley so that the transfer’s line of action passes toward the pisiform produces maximal thumb abduction and opposition but only a small amount of flexion at the thumb MCP joint, whereas placing it so that the transfer’s line of pull passes distal to the pisiform produces more thumb MCP joint flexion and less abduction. Thus, a distally placed pulley may benefit patients with combined ulnar and median nerve palsies and paralyzed FPB muscles.

Surgical techniques

Royle-Thompson opponensplasty. With this technique, a 3-cm longitudinal incision is made at the base of the palm on the radial border of the hypothenar eminence. ^, The ulnar border of the palmar aponeurosis is exposed and retracted radially, and the ring finger superficialis tendon is identified as it emerges from the carpal tunnel proximal to the superficial palmar arch. This tendon is then divided distally through a transverse incision at the base of the digit and delivered into the palmar wound so that it passes ulnar to the palmar aponeurosis. A third incision is made over the dorsum of the thumb MCP joint, and a wide subcutaneous tunnel is created between this and the palmar incision. The superficialis tendon is passed through this tunnel, with the angle created by the distal edge of the flexor retinaculum and the ulnar border of the palmar aponeurosis acting as the pulley. The transfer is then attached to the thumb by one of the many insertion techniques. Although Thompson originally used a dual insertion that stabilized the thumb MCP joint, he subsequently used the APB insertion.

The tourniquet is released and hemostasis is obtained before the incisions in the palm and at the base of the ring finger are closed. The superficialis transfer attachment to the thumb is then sutured while the thumb is held in full opposition. Because the ring finger superficialis tendon has a significant potential for excursion and crosses the wrist joint, adjusting the tension is not as critical as with other transfers, and there is a considerable margin for error. However, the transfer’s tension should be adjusted so that it is tight when the thumb is fully opposed and the wrist is in neutral. Postoperatively, Thompson held the thumb in opposition for 4 to 6 weeks with spiral adhesive strapping that allowed some active thumb movement; in addition, Rath advocated early mobilization of this transfer. However, most surgeons immobilize the thumb in full opposition with a cast for several weeks.

results. Some surgeons believe that this opponensplasty does not produce as wide a thumb abduction as some other transfers because it runs along the path of the superficial head of the FPB and not that of the APB muscle. However, the results were excellent or good in 8 of Thompson’s 10 original opponensplasties, and a subsequent report described excellent or good results in 78% of 94 opponensplasties.

Bunnell’s opponensplasty. Bunnell’s precept for restoration of full thumb opposition was that the transfer should run in line with the fibers of the APB to an insertion on the dorsoulnar aspect of the thumb proximal phalanx. Because his transfer passes distal to the axis of rotation of the MCP joint, it also flexes that joint.

technique. The ring finger superficialis tendon is divided at the base of this digit by using one of the previously described techniques. An incision is then made over the ulnar neurovascular bundle, just proximal to the wrist crease, and the ring finger superficialis tendon is identified. The distal portion of the FCU tendon is then exposed and cut halfway across, 4 cm proximal to its insertion on the pisiform. The tendon is then split into two equal halves up to its pisiform insertion, thus creating a distally based strip of tendon tissue. The free end of this tendon slip is sutured back onto its base at the pisiform to create a fixed pulley through which the superficialis tendon can pass easily. Care should be taken to not make this loop too tight. An incision is then made on the dorsum of the thumb, and a wide subcutaneous tunnel is created across the palm between the two incisions. A hole large enough to accommodate the superficialis tendon is then drilled from the dorsoulnar cortex to the radial cortex of the base of the proximal phalanx. The ring finger superficialis is delivered into the wrist incision and passed through the pulley and then along the subcutaneous tunnel into the dorsal thumb incision.

Next, the tourniquet is released, hemostasis is achieved, and the skin incisions at the base of the ring finger and at the wrist are closed. The superficialis tendon is then passed superficial to the EPL tendon across the dorsum of the thumb MCP joint. It is then passed through the drilled hole in the base of the proximal phalanx in a dorsoulnar-to-radiopalmar direction. Once the tendon has been passed through the drill hole, the transfer’s tension is set so that the thumb lies in full opposition with the wrist in neutral. The transfer is then sutured back onto itself or to the radial border periosteum. Alternatively, it can be held with a pull-out suture tied over a dental roll or attached to the proximal phalanx with suture anchors.

results. Jensen used the Bunnell opponensplasty and reported good opposition in 22 of his 27 superficialis transfers.

EIP opponensplasty

The EIP opponensplasty was favored by Burkhalter, who wrote earlier editions of this chapter, and is popular in high median nerve palsy and other instances when the ring and middle finger FDS tendons are unavailable. It has become increasingly preferable to the superficialis transfer in low median nerve palsies because it does not weaken grip and causes little, if any, functional disability.

Technique

A short incision is made over the index finger MCP joint, and the EIP tendon is identified lying deep and ulnar to the index EDC. It can be divided immediately proximal to the extensor hood, but the tendon is then only just long enough to reach the APB insertion on the thumb. As a result some surgeons, myself included, recommend that a 1- to 2-cm contiguous slip of the extensor hood is harvested with the tendon to lengthen the transfer ( Fig. 31.3A ). This makes the attachment of the transfer to the ADM insertion much easier but requires careful repair of the extensor hood, as otherwise its radial and ulnar halves may subluxate palmarly and cause an extensor lag. An incision is then made on the dorsoulnar aspect of the distal forearm and the deep fascia on the ulnar border of the extensor compartment is widely released to expose the finger extensor tendons proximal to the extensor retinaculum. The EIP muscle and tendon lie deep and ulnar to the EDC tendons and are identified by pulling on the distal end of the EIP tendon on the back of the hand (see Fig. 31.3B ). The whole EIP tendon is pulled down from the back of the hand into the forearm wound, which is sometimes only possible after soft tissue connections between the extensor indicis and index communis tendons have been divided through a small incision on the back of the hand. The EIP muscle is then freed of soft tissue attachments in the distal third of the forearm (see Fig. 31.3C ).

Fig. 31.3, Extensor indicis proprius (EIP) transfer. A, The extensor indicis proprius tendon is harvested from the index finger. The tendon here has been extended by 1 to 2 cm with a slip of the extensor hood. The extensor hood has been repaired but the sutures are hardly visible. B, An incision is made on the dorsoulnar aspect of the distal forearm and the EIP muscle is identified. C, The end of the EIP tendon is passed from the incision at the base of the index finger into the dorsoulnar forearm incision. In my practice this often requires release of soft tissue connections between the index EDC and the EIP, to allow the EIP tendon to be first withdrawn into a third incision on the dorsum of the hand (at the tip of the forceps in this picture). D, The EIP tendon is passed around the ulnar border of the distal forearm to the planned insertion onto the abductor pollicis brevis insertion. I mark the path on the skin to allow accurate placement of the subcutaneous tunnels for the transfer. E, A subcutaneous tunnel is created between one incision on the palmar-ulnar aspect of the distal forearm and another over the abductor pollicis brevis (APB) insertion. The fine blue dots on the skin mark the pathway for the transfer. F, After ensuring the deep fascia over the fourth extensor compartment is widely divided down onto the ulna, the EIP tendon is passed from the dorsoulnar forearm incision into the palmar-ulnar forearm incision. It is then passed subcutaneously across the palm to the abductor pollicis brevis insertion. It must have a straight line of pull around the ulna and across the palm to the APB insertion. G, All the skin incisions for the harvest and transfer of the EIP tendon are closed, and then the EIP transfer is sutured to the APB tendon insertion using a Pulvertaft weave. The tension should be set “rather too tight” than “rather too lax,” as a transfer that is too lax will not work. H, Cyano-acrylate glue can be used to stick the thumb tip to the ring or little fingertip in opposition. A plaster backslab is then applied across the back of the wrist and thumb. This author holds the wrist slight flexion and the thumb opposed to the ring or little fingertip.

Next, the path of the transfer is planned and marked (see Fig. 31.3D ), and small incisions are made in the pisiform area on the ulnar border of the wrist and on the dorsoradial aspect of the thumb MCP. A wide subcutaneous tunnel is then developed from the extensor surface of the forearm to the thumb incision, passing around the ulnar border of the wrist and across the palm (see Fig. 31.3E ). The extensor indicis tendon is passed through this tunnel, running superficial to the EDC and FCU tendons (see Fig. 31.3F ). Inadvertently passing it beneath the FCU tendon may later result in compression of the ulnar nerve. The tourniquet is then released and hemostasis obtained before the forearm and index finger incisions are closed. The distal attachment of this transfer depends on the clinical setting. In isolated median nerve palsies, it is simply attached to the APB tendon with the wrist in 30 degrees of flexion and the thumb in maximum opposition. My preference is to attach the transfer with a Pulvertaft weave (see Fig. 31.3G ).

In combined median and ulnar nerve palsies with an intrinsic-minus thumb, the transfer may be attached in sequence to the APB tendon, the MCP joint capsule, and the EPL tendon over the proximal phalanx, as described by Riordan. The transferred tendon can reach this new origin if the thumb is fully opposed and the wrist is flexed. This attachment restricts IP joint flexion and thus allows the FPL to flex the MCP joint more effectively and substitute for the paralyzed FPB. Alternatively, a split FPL tendon transfer can be performed to achieve a similar outcome (page 1222). Postoperatively, the hand is immobilized with the wrist in flexion and the thumb in full opposition (see Fig. 31.3H ) for 3 to 4 weeks.

Results

Burkhalter and colleagues reported the results of extensor indicis opponensplasty in 65 trauma cases, which included 32 combined ulnar and median nerve, 13 high median nerve, and 2 brachial plexus injuries. Of the patients, 86% achieved excellent results, with powerful opposition to within 20 degrees of the plane of the palm of the hand. Perceived additional benefits of this transfer included ease of surgery (performed satisfactorily by residents) and rehabilitation (its excursion is naturally augmented by a wrist tenodesis effect). A disadvantage is that extensor indicis muscle-fiber length is shorter than that of the APB and the ring finger superficialis, so thumb extension may be restricted.

Anderson and associates used this transfer in 12 high and 28 low median nerve palsies caused by leprosy, trauma, and other conditions. In contrast to Burkhalter’s description, they attached the transfer to the thumb with the wrist in neutral and the thumb fully abducted and extended. Excellent or good results were seen in 88% of the cases monitored for more than a year. These investigators subsequently compared these results with those achieved by superficialis transfer and concluded that the EIP transfer should only be used in supple hands.

ADM (Huber) opponensplasty

The ADM opponensplasty ( Fig. 31.4 ), described independently by Huber ^, and Nicolaysen, ^, was popularized by Littler and Cooley, who considered the ADM a close substitute for the APB. This transfer may improve the hand’s appearance by increasing the bulk of the thenar eminence.

Fig. 31.4, Huber abductor digiti minimi (ADM) opponensplasty. Two incisions are required to expose and transfer the ADM (Abd. dig. v.) . The neurovascular structures enter the muscle proximally on its deep and radial aspect. The muscle is freed from the other hypothenar muscles, and its origin on the pisiform (P) is elevated while preserving a tendinous attachment to the tendon of the flexor carpi ulnaris (F.C.U.) . The ADM is then rotated 180 degrees on its long axis and passed subcutaneously to the area of the thumb MCP joint. The distal attachment is to the APB muscle. Flex. br., Flexor digiti minimi brevis; P.M. lig., pisometacarpal ligament.

Technique

A midlateral incision is made on the ulnar border of the little finger proximal phalanx and extended proximally and radially to the distal palmar crease. It then runs along the radial border of the hypothenar eminence and curves ulnarly as it crosses the distal wrist crease. The two ADM insertions (i.e., base of the proximal phalanx and extensor apparatus) are divided, and this muscle is then freed of soft tissue attachments by retrograde dissection toward its pisiform origin. When mobilizing the proximal portion of the ADM, great care must be taken to not damage its thin neurovascular pedicle, which is on its dorsoradial aspect. Alternatively, this pedicle can be identified by exposing the ulnar nerve and artery proximally at the wrist and tracing them distally.

Once the neurovascular bundle has been isolated, the transfer’s length is increased by elevating the abductor origin from the pisiform while carefully retaining an attachment on the FCU tendon by dissecting a tendinous slip proximally. The transfer’s only remaining soft tissue attachments are then its neurovascular pedicle and the FCU tendon. Next, a dorsoradial incision is made over the thumb MCP joint and a wide subcutaneous tunnel is created between this incision and the area immediately proximal to the pisiform; this is easier if a third skin incision is made in the thenar crease at the base of the thenar eminence (not shown in Fig. 31.5 ).

Fig. 31.5, Camitz transfer. The palmaris longus is elongated with a strip of palmar aponeurosis and attached to the abductor pollicis brevis insertion.

The ADM muscle is then turned through 180 degrees on its long axis to reduce the tension on its neurovascular bundle (as if turning the page of a book), passed through the subcutaneous tunnel, and attached to the APB insertion. Because the ADM muscle has only sufficient length to just reach the APB insertion, it is invariably attached under adequate tension. Postoperatively, the thumb is immobilized in a cast in full opposition for 4 weeks. The position of the wrist is not critical inasmuch as the transfer does not cross this joint.

Results

Littler and Cooley performed four Huber transfers, one of which failed and became fibrotic, probably as a result of vascular insufficiency. They considered this transfer difficult and recommended that it be performed only when simpler opponensplasties are contraindicated. Furthermore, primate studies have highlighted this transfer’s precarious blood supply, which is significantly reduced by dividing its pisiform insertion. In light of these concerns, some surgeons retain the pisiform origin and lengthen the transfer with a short tendon graft when necessary. Others, in complete contrast, lengthen the transfer by completely releasing the origin of ADM, which they leave to reattach itself by scar tissue formation.

Wissinger and Singsen preserved the pisiform origin in 15 Huber transfers and reported one failure as a result of transfer fibrosis. Twelve of their cases achieved excellent results with no donor site morbidity. Some surgeons use the Huber transfer as the opponensplasty of choice in pediatric patients with congenital thenar muscle deficiencies (see Chapter 37 ). One consideration in this scenario is that an FDS transfer allows augmentation of the deficient UCL in affected children, whereas a Huber does not have sufficient length to achieve this.

Palmaris longus opponensplasty (Camitz)

The Camitz PL opponensplasty (see Fig. 31.5 ) is a simple transfer that is usually performed for loss of abduction and opposition occurring as a complication of severe carpal tunnel syndrome. The procedure restores palmar abduction rather than opposition, but it can be performed under regional anesthesia at the same time as carpal tunnel release. It is reasonable to perform a Camitz procedure at the same time as carpal tunnel release for patients with severe thenar wasting and loss of abduction and opposition that is causing functional disability, even though thumb opposition and abduction may recover after carpal tunnel release, over a period of months ( Fig. 31.6 ). This transfer is not recommended for traumatic median nerve injuries at the wrist because the PL, which lies directly over the median nerve, and the overlying skin are usually scarred and damaged. However, its use has been utilized in this situation in young children.

Fig. 31.6, A and B, A patient presented with long-standing carpal tunnel syndrome and thenar muscle atrophy with loss of abduction and opposition. A Camitz transfer was performed at the same time as a carpal tunnel release, and excellent thumb abduction was restored. Thumb pronation was provided by the weak flexor pollicis brevis.

Technique

Preoperatively, the presence of the PL tendon is confirmed by opposing the thumb to the little finger with the wrist flexed. A longitudinal skin incision is made, starting in the forearm, 2 cm proximal to the distal wrist crease, zigzagged across the transverse wrist crease (see Figs. 31.5 and 31.6A ) and running distally to the proximal palmar crease in line with the ring finger. Care needs to be taken to identify and avoid injury to the palmar cutaneous branch of the median nerve, which lies just radial to the PL tendon. The PL tendon is freed from the forearm to the palm, where a 1-cm-wide strip of palmar aponeurosis is dissected out in continuity with the tendon. The carpal tunnel is decompressed, and a second incision is made over the dorsoradial aspect of the thumb MCP joint. A wide subcutaneous tunnel is then developed from the distal forearm to the incision over the thumb MCP joint, and the PL tendon and its aponeurotic extension are passed through this. It is necessary to ensure a straight line of pull of the PL from its origin on the medial epicondyle to the APB insertion, and this will require separation of the subcutaneous tissues from the deep fascia on the radial aspect of the incision in the distal forearm and also more proximal division of the deep fascia covering the PL in the distal forearm.

The palmar skin incision is then closed and the tendon transfer is usually attached to the APB insertion, with or without another attachment to the dorsal MCP joint capsule, which may increase opposition. ^, ^, Foucher and coworkers favor attachment to either the EPB tendon or the dorsal capsule of the MCP joint in an effort to restore opposition as well as abduction. Whichever distal attachment is used, it is sutured with the thumb in full opposition, the MCP joint extended, and the wrist in neutral. The thumb incision is then closed, and a light cast, holding the wrist in neutral and the thumb opposed, is worn for 4 weeks. A night splint may be worn for a week or two longer.

Results

In a series of 73 Camitz procedures performed for severe carpal tunnel syndrome by Foucher and coworkers, 50% of the patients regained good opposition within 1 year and 91% regained good thumb abduction and satisfactory opposition by 16 to 102 months. Attaching the PL tendon to the dorsal capsule of the MCP joint or the EPB tendon restricted MCP joint movement slightly (15 to 25 degrees) in 20% of the patients in this series. Braun successfully used the Camitz procedure to reestablish thumb abduction in 28 cases, whereas Terrono and colleagues improved thumb function in 27 of 29 cases and believed that formal physiotherapy was unnecessary.

What we call the Camitz transfer was actually first described by Bunnell, who also suggested passing the PL tendon through a pulley close to the pisiform to create a more oblique line of pull and restore opposition. Passage of the transfer through a window in the flexor retinaculum has also been suggested. If the superficial head of the FPB muscle is innervated by the ulnar nerve, this may provide pronation and thus allow use of a standard Camitz procedure to restore good opposition.

Other opponensplasties for special situations when none of the “big four” are appropriate

ECU opponensplasty

The ECU opponensplasty described by Phalen and Miller avoids the need for a tendon graft by utilizing the EPB tendon and its insertion. ^,

Technique

A short incision is made on the dorsoradial border of the distal forearm, and the EPB tendon is divided at its musculotendinous junction, just proximal to the first extensor compartment. An incision is then made on the extensor surface of the thumb MCP joint, and the EPB tendon is delivered into this wound while preserving its insertion on the proximal phalanx. Next, an “L”-shaped incision is made on the ulnar border of the wrist, its short arm passing transversely along the flexor wrist crease toward the PL. A wide subcutaneous tunnel running from the thumb MCP joint to the pisiform area is then created across the palm. The EPB tendon is passed proximally through this tunnel, and the ECU tendon is then divided close to its insertion on the base of the fifth metacarpal. It is then withdrawn back under the extensor retinaculum and freed of soft tissue attachments throughout the distal third of the forearm. Care should be taken to identify and preserve the dorsal sensory branch of the ulnar nerve during this dissection. The ECU tendon is then passed around the ulnar border of the distal forearm (deep to the dorsal sensory branch of the ulnar nerve and superficial to FCU and the main ulnar neurovascular bundle) and sutured to the EPB tendon while the thumb is opposed to the base of the middle finger with its MCP and IP joints extended. Postoperatively, the thumb is immobilized in opposition with the wrist in neutral for 3 to 4 weeks.

Results

Wood and Adams performed this procedure on 12 patients’ complex cases with few available motors. In four instances they observed radial deviation wrist deformities that caused severe grip weakness. This may have occurred as a result of FCU paresis or paralysis, but an anomalous ECRL insertion onto the radial, rather than the dorsal, border of the index metacarpal was also implicated. In two patients the radial deviation deformity was corrected by transferring the ECRL tendon to the distal ECU stump.

There are three other problems with this transfer. First, the EPB tendon is sometimes nonexistent. Second, an MCP joint flexion deformity may occur if the EPB tendon is dissected out from the extensor hood right up to its insertion on the proximal phalanx. In contrast, MCP joint hyperextension may occur if it is not dissected out sufficiently distally. Third, a tendinous slip sometimes connects the EPB and EPL tendons; if present, this must be divided as the transfer may otherwise cause unwanted extension of the IP joint.

ECRL opponensplasty

The tendon of the ECRL muscle needs to be lengthened, and this can be done with a standard tendon graft. Alternatively, the ECRL (or ECRB) tendon may be detached distally at its insertion onto the index metacarpal, brought out into a wound in the dorsal forearm, and then carefully split in half longitudinally, such that one strip remains attached to the ECRL muscle and the other half is free. The free strip of tendon is then sutured to the distal end of attached strip to lengthen the transfer. The elongated transfer is passed through a wide subcutaneous tunnel around the ulna, just proximal to the pisiform, and inserted into the APB attachment and EPL.

Kaplan and coworkers described an alternative technique of elongating the ECRL tendon with the EPL tendon.

Technique

A skin incision is made over the dorsum of the distal radius, and the EPL tendon is divided at its musculotendinous junction. The ECRL tendon is then divided close to its insertion and freed of soft tissue attachments in the distal forearm. Next, the EPL tendon is delivered into a second incision on the extensor surface of the thumb MCP joint, and a third skin incision is made on the border of the wrist at the level of the ulnar styloid process. Wide subcutaneous tunnels are then created across the palm and around the ulnar border of the wrist/distal forearm. The EPL tendon is passed through the palmar tunnel to the wrist’s ulnar border, which may require a fourth incision in the midpalm. It is then sutured to the ECRL tendon with the wrist flexed and the thumb abducted and opposed. Postoperatively, the hand is immobilized with the wrist flexed and the thumb opposed in a below-elbow cast for 3 weeks.

Results

Kaplan and coworkers reported this transfer in four patients with isolated median or combined median and ulnar nerve injuries. All the four thumbs regained abduction and opposition, and thumb IP joint flexion and extension were preserved. Henderson also used the ECRL in 5 patients, all of whom regained satisfactory opposition. Baek and colleagues achieved excellent results in 10 of 11 cases and preferred it to the EIP opponensplasty as it provided stronger opposition. None of these authors report the impact of the loss of normal EPL function, which would be expected to restrict thumb extension and retroposition.

EDM opponensplasty

The EDM can be used for an opponensplasty, particularly when the EIP is not available, usually because it has been used, or will be used, for another transfer. It is important for the surgeon to have an alternate transfer in mind in the event that the EDM is determined to be insufficient or absent.

Technique

An incision is made over the little finger MCP joint and the EDM tendons (i.e., usually two tendons) are identified on the ulnar side of the little finger’s common extensor tendon. These tendons and, in continuity with them distally, a central section of the extensor hood over the proximal portion of the proximal phalanx are freed distally and withdrawn proximally, back under the extensor retinaculum into an incision on the dorsoulnar aspect of the distal forearm. The tendons are then freed of soft tissue attachments in the distal third of the forearm, and the little finger extensor hood is carefully repaired with interrupted, nonabsorbable sutures. The transfer is then passed subcutaneously around the ulnar border of the wrist and across the palm, using the technique described for EIP transfer. In the original description this transfer was attached to the APB, the extensor expansion, and the EPL tendon over the base of the proximal phalanx. Postoperatively, the thumb is immobilized in opposition with the wrist in neutral for 3 weeks.

Results

Schneider reported good opposition in 8 of 10 cases, most of which were combined median and ulnar nerve injuries. However, patients should be counseled that an extension lag of the little finger may occur, despite careful repair of the extensor hood after harvest of the elongated tendon (necessary to ensure adequate length). It may be advisable to perform preoperative ultrasound to assess the integrity of the EDC contribution to the small digit, which is not uncommonly deficient.

Tendon transfers (“compromise opponensplasty”) for severe nerve deficits

In a complete or nearly complete intrinsic-minus thumb, such as occurs in combined median and ulnar nerve palsies, the FPL and EPL muscles both adduct and supinate the thumb. Furthermore, the combined overactivity of these two extrinsic muscles causes the IP joint to hyperflex and the MCP joint to extend ( Fig. 31.7 ). The hyperflexed IP joint prevents the thumb pulp from meeting the index finger properly in either pulp or key pinch, and the fingers tend to strike the nail or the dorsum of the thumb, which is disabling and causes thumb supination ( Fig. 31.8 ). However, a patient usually can hold objects between the adjacent sides of the thumb and hand (lateral squeeze) and often prefers this “pinch” to that provided by an opponensplasty that the patient therefore does not use (see Fig. 31.2 ). It is thus an attractive concept, which stems from the days of poliomyelitis, to use one of these extrinsic thumb muscles for an opponensplasty.

Fig. 31.7, This 19-year-old man sustained high median and ulnar nerve injuries when aged 10. Wound issues prevented early repair but both nerves were reconstructed with sural nerve grafts. After 1 year there was no recovery of intrinsic function in the hand and he underwent an EIP opponensplasty and also an ECRL to lateral band transfer to correct finger clawing. At 9 years post-transfers, he represented having felt something give in his middle finger with recurrent clawing of this digit. I wondered if the graft (plantaris) for the ECRL transfer had snapped. He had excellent opposition and was functioning well. However, his thumb IP joint went into marked flexion when pinching and opposing. He may have benefited from an FPL tenodesis or IP joint fusion to prevent excessive flexion of the IP joint, but felt he had adequate function and did not wish further treatment. I cannot exclude the possibility of some recovery of median nerve function.

In progressive severe paralysis, a combination of two tendon transfers—one to provide opposition and the other to restore FPB function—is a luxury, and the hand may not have sufficient function to benefit from true opposition. In such instances, restoration of short flexor action alone often provides adequate thumb function. This can be produced by a single-tendon transfer in conjunction with either thumb joint fusion or an IP joint tenodesis.

FPL opponensplasty

An FPL transfer only provides limited pronation and is used for patients with severe hand paralysis for whom pinch of the thumb pulp to the sides of the index or long fingers is more important than pinch to the pulp. The desired end result is a single-axis thumb that can clear the fingers and oppose the fingertips and their sides with considerable power.

Technique ( Fig. 31.9 )

If a tenodesis of the IP joint is planned, the FPL is exposed distally through an incision starting on the dorsum of the IP joint and running palmarly down the radial side of the proximal phalanx. The FPL tendon is then divided 1 cm proximal to the IP joint and the periosteum is stripped from the palmar surfaces of the neck and distal shaft of the proximal phalanx. The distal stump of the FPL is then firmly tenodesed to the proximal phalanx with the IP joint in 15-degree flexion.

Fig. 31.9, A, Flexor pollicis longus (FPL) opponensplasty. Technique described by Mangus. A, The flexor pollicis longus tendon is exposed in the distal thumb and divided over the shaft of the proximal phalanx. The distal portion of the FPL is used to tenodese the phalangeal joint in 15 degrees flexion. The proximal portion of the tendon is brought out of a wound on the palmar-radial aspect of the distal forearm. B, The FPL is then passed ulnarly in the plane between the FDP and FDS tendons and around the flexor carpi ulnaris tendon. It is then passed through a wide subcutaneous tunnel into a wound on the radial aspect of the thumb MCP joint where it is attached to the distal tendon of the superficial head of the flexor pollicis brevis (or alternatively the distal tendon of abductor pollicis brevis). C, Alternative technique of FPL opponensplasty recommended by Burkhalter (described in previous editions of this book). The FPL is divided at its insertion onto the distal phalanx of the thumb and passed proximally into an incision on the palmar-radial aspect of the distal forearm. It is then passed in the plane between the FDP and FDS tendons through the carpal tunnel into an incision just radial to the thenar eminence at the base of the palm, in the line of the ulnar border of the ring finger. The tendon is then passed upward, just distal to the flexor retinaculum and ulnar to the palmar aponeurosis. It is then passed through a wide subcutaneous tunnel to the dorsoradial aspect of the thumb MCP joint where it is joined to the superficial head of the flexor pollicis brevis tendon. The interphalangeal joint is fused. The current author is uncertain whether an FPL tenodesis would be possible with this technique as he wonders if the tendon transfer might be too short if the distal 1 to 2 cm of the FPL tendon is retained on its insertion on the distal phalanx to tenodese the IP joint.

If an IP joint fusion is planned, then Burkhalter suggests the distal attachment of FPL is exposed and divided through a zigzag incision on the flexor surface of the IP joint. A “Y” incision is then made over the dorsum of that joint and the EPL tendon is divided to leave a small distal stump. The IP joint is then fused in extension, and the EPL is repaired.

With both techniques the FPL tendon is delivered into an incision on the radiopalmar aspect of the wrist. Sometimes this is possible only after adhesions between the tendon and the radial palmar bursa have been divided at the level of the A1 pulley. The FPL is then passed around a pulley on the ulnar border of the hand; any of the superficialis transfer pulleys described earlier in this chapter can be used.

Mangus used the FCU tendon as his pulley, presumably with the FPL crossing the distal forearm in the plane between the flexor digitorum profundus (FDP) and FDS tendons. After passing the FPL under, around, and back over the FCU tendon alone, it is passed across the front of the wrist and palm in a wide subcutaneous tunnel to an incision on the radial aspect of the thumb MCP point.

If the Thompson pulley is chosen, a palmar incision is made in line with the ulnar border of the ring finger. Next, the FPL tendon is passed through the carpal tunnel, between the superficialis and profundus flexor tendons, and is delivered into the palmar incision. An incision is then made over the dorsoradial aspect of the thumb MCP joint, and the FPL tendon is passed through a wide subcutaneous tunnel into this incision. After the tourniquet has been released and hemostasis obtained, all incisions, except the last one, are closed.

The FPL tendon is usually attached to the superficial head of the FPB rather than the APB. This allows the transfer to stabilize the MCP joint in slight flexion as well as abduct and, to a lesser extent, pronate the thumb. Furthermore, if the APB is used as the insertion, thumb opposition and flexion will be much weaker. Because the FPL muscle has a large potential excursion, setting the tension in this transfer is relatively easy and the thumb should rest in almost full opposition at the end of the procedure.

The hand is immobilized postoperatively with the wrist in 40 degrees of flexion and the thumb in full opposition for 3 weeks. Rehabilitation is then begun by using active wrist extension to bring the thumb into opposition. This is followed by exercises to increase the strength of the transfer.

Results

Burkhalter believed that this transfer had distinct advantages for the completely intrinsic-minus thumb, in which case short flexor action is more important than opposition. He found that EPL overactivity tended to disappear, and his patients quickly realized that they had a functional short flexor muscle and no longer needed to use the EPL as a secondary thumb adductor. After this transfer, the patient uses the EPL to move the thumb away from the fingers and the FPL opponensplasty for prehension activity.

Alternative FPL opponensplasties

Makin transferred the FPL “in continuity,” without dividing the tendon or its insertion, by passing it through an oblique osteotomy in the proximal phalanx so that it spirals around the proximal phalanx and the MCP joint ( Fig. 31.10 ). Oberlin and Alnot used a similar technique in 11 intrinsic-minus thumbs and reported very good results in 8 of the 9 cases reviewed. Rather than passing the FPL tendon through an osteotomy, they passed it through either the IP or the MCP joint, which was then fused. They stressed that the transfer must pass over the extensor surface of the MCP joint and not over the dorsum of the proximal phalanx, which can cause a flexion deformity of the MCP joint ( Fig. 31.11 ). These authors recommended this transfer for completely intrinsic-minus thumbs in high nerve injuries but favored EIP opponensplasty and MCP joint arthrodesis if there were no fixed deformity of the IP joint. Neither of these alternative FPL opponensplasty techniques can reroute the FPL tendon in the forearm, wrist, or palm, such that both are more abductorplasties than opponensplasties.

Fig. 31.10, Makin’s flexor pollicis longus (FPL) opponensplasty. A, A bayonet incision is made on the radial aspect of the thumb. The radial neurovascular bundle is protected, and the proximal phalanx is exposed by subperiosteal dissection around its circumference. The flexor sheath is released throughout its length to allow retraction of the FPL tendon. B, An oblique osteotomy is made in the proximal phalanx and the FPL tendon is passed through this so that distally it passes around the ulnar border of this bone. It then runs over the extensor surface of the metacarpophalangeal joint before passing radially over the neck of the metacarpal. C, The osteotomy is then stabilized with a longitudinal Kirschner wire (or interfragmentary screws) until union.

Fig. 31.11, Oberlin’s flexor pollicis longus (FPL) opponensplasty. A, A longitudinal incision is made on the radial aspect of the thumb. The radial neurovascular bundle is protected, and the flexor sheath is released throughout its length to allow retraction of the FPL tendon. B, The soft tissue attachments to the proximal phalanx are released circumferentially from its neck distally to the metacarpophalangeal (MCP) joint; then the joint capsule is completely divided and the FPL tendon is passed through it so that distally it passes around the ulnar border of the shaft of the proximal phalanx. It then runs over the extensor surface of the MCP joint before passing radially over the neck of the metacarpal. C, The MCP joint is then fused and stabilized until union. The position of the FPL can be fixed on the radial aspect of the neck of the metacarpal by dividing the insertion of abductor pollicis brevis, placing FPL under the tendon, and then repairing the insertion. This transfer can be performed through the interphalangeal joint rather than the MCP joint, in which case it is the former that is fused; great care must be taken to ensure that the transfer passes over the back of the MCP joint. If it passes over the back of the proximal phalanx, it may flex the MCP joint.

EPL opponensplasty

In some cases of peripheral nerve disease or spastic paralysis, when the only functioning thumb extrinsic or intrinsic motors are the EPL, EPB, and APL, an IP joint flexion contracture may occur even though the FPL is weak or totally paralyzed. This is due to a tenodesis effect of the FPL, which occurs as the functioning thumb muscles extend and supinate the trapeziometacarpal and MCP joints. In this situation, the extension and supination deformity at the base of the thumb may be corrected by an intermetacarpal bone block (i.e., static correction) or an EPL opponensplasty ( Fig. 31.12 ) if this muscle is under voluntary control. If a spastic EPL is transferred, the thumb will lie in front of (and get in the way of) the fingers because the APL on its own is not sufficiently strong to hold the thumb out of the palm.

Technique

An incision is made on the extensor surface of the proximal phalanx and MCP joint of the thumb. The EPL tendon, with a contiguous central portion of the extensor expansion and the central portion of its insertion onto the distal phalanx, is freed from its insertion on the distal phalanx while preserving the radial and ulnar portions of the extensor hood over the proximal phalanx and the MCP joint and the radial and ulnar edges of the EPL insertion onto the distal phalanx. This tendon is then withdrawn into an incision on the extensor surface of the wrist and distal forearm, and a further incision is made near the pisiform. The EPL tendon is passed through a wide subcutaneous tunnel that runs around the ulnar border of the wrist and across the palm to the initial thumb incision. Next, the thumb MCP joint is fused in almost full extension and some pronation ( Fig. 31.13 ).

Fig. 31.13, If the thumb metacarpophalangeal joint is fused in flexion, the index finger exerts a powerful supinatory effect on it during pinch. The moment arm is the entire length of the distal and proximal phalanges of the thumb. This is the same crank-handle effect as shown in Fig. 31.8, but with an even longer moment arm.

The transferred EPL tendon is then looped around the lateral portions of the extensor hood at the level of the MCP joint and sutured back onto itself. The two lateral portions of the extensor hood over the proximal phalanx are sutured together, thereby restoring continuity of the EPL and preserving extension of the IP joint (see Fig. 31.12F ). The IP joint is then held in extension with Kirschner wires, and the hand is immobilized with the thumb in full opposition and the wrist in 40 degrees of flexion. It is most important for the fixation of the MCP arthrodesis to be secure so that this transfer can be mobilized actively within 4 weeks, while the arthrodesis is not yet solid. At that stage the patient should be taught to differentiate between EPL and APL function. It is also important to ensure after completion of the transfer that it is possible for the fingers to clear the thumb with the wrist in neutral because, after this transfer, only the EPB and APL extend the thumb.

Results

Riley and colleagues used this transfer in 11 patients with progressive neurologic disease (e.g., syringomyelia and Charcot-Marie-Tooth) or traumatic high median or combined median and ulnar nerve intrinsic paralyses. They reported satisfactory results in view of the severity of the original motor deficit and found that the APL and EPB muscles were always able to extend the thumb sufficiently to clear the palm and not impede finger flexion. However, all the patients had a diminished range of retroposition.

Alternative EPL opponensplasties

Moutet and associates and Mennen have used EPL opponensplasties more routinely, both for isolated and combined median nerve injuries. However, instead of transferring the EPL tendon around the ulnar border of the wrist, they both passed it through a window in the interosseous membrane. Moutet and associates then passed it around either the FCR (isolated median nerve injury) or the FCU (combined median and ulnar nerve injury) tendon, and both sutured the transfer back onto the divided distal end of the EPL. Neither fused the MCP joint.

Mennen’s technique of EPL opponensplasty

The EPL tendon is exposed through an incision on the extensor surface of the MCP joint and divided 1 cm proximal to this joint. This tendon is then delivered into a second incision on the extensor surface of the forearm. The tendon and its muscle are freed of soft tissue attachments throughout the distal half of the forearm. An incision is made on the flexor surface of the forearm 3 cm proximal to the wrist crease and just radial to the ulnar artery. The interosseous membrane is then exposed between the ulnar neurovascular bundle and the finger flexor tendons, and a window is made that is large enough to easily accommodate the distal portion of the EPL muscle.

A subcutaneous tunnel is then created between the incisions on the anterior of the forearm and back of the thumb, and the EPL tendon is passed through the interosseous membrane and subcutaneously along the thenar eminence to the extensor surface of the thumb MCP joint. Here it is passed under the EPB tendon and reattached to its own distal stump with a 1-cm overlap. The thumb is immobilized in a short-arm thumb spica cast for 4 weeks, and a dynamic opposition splint is then used for another 4 weeks.

Results. By using this technique, Mennen regained normal opposition between the thumb and little finger pulp in 26 of 35 cases and also found that normal power of extension of the thumb’s IP joint was retained. In the series by Moutet and associates, 14 of 16 patients recovered functional opposition, and the results remained satisfactory 13 years later.

Adductor pollicis and FPB opponensplasties

DeVeechi transferred the AP to the insertion of the superficial head of the FPB. This transfer requires an extensive palmar incision that extends from the adductor insertion across the palm toward the middle finger metacarpal and then proximally toward the base of the thumb. The carpal tunnel is opened, and the median nerve and its branches are protected. The adductor tendon is then divided at its insertion and freed from the FPB. It is passed superficial to the index finger flexor tendons, the index/middle common digital neurovascular bundle, and the FPL tendon and attached to the superficial head of the FPB. This transfer restores FPB function and provides some thumb pronation but does not produce true opposition.

Orticochea transferred the ulnar-innervated deep head of the FPB around the extensor surface of the thumb and attached it to the aponeurosis of the adductor tendon.

Postoperative management of opponensplasty

The thumb is usually immobilized in opposition for 3 weeks after opponensplasty. However, early controlled mobilization is possible with a robust attachment of the transfer to the APB insertion and MCP capsule. The wrist should also be immobilized if the tendon transfer crosses the flexor surface of this joint. Transfers of muscles with relatively short excursions (e.g., the EIP) should be relaxed by immobilizing the wrist in 30 degrees of flexion and the thumb in full opposition. However, after transfer of muscles with larger excursions (e.g., the superficialis) the wrist can be immobilized in neutral with the thumb in full opposition. If the transfer is attached to either the extensor mechanism or the APB insertion, the IP joint of the thumb probably should also be immobilized in full extension.

Some find it useful to maintain thumb opposition postoperatively by using cyanoacrylate glue to stick the skin of the thumb tip to the ring or little finger at the end of the operation, before the transfer’s tension is set. With desquamation, the thumb is spontaneously released from the finger after 2 to 3 weeks (see Fig. 31.3H ). After 3 weeks, all splintage usually can be discarded and most patients quickly regain thumb control. The emphasis should be on early restoration of wrist movement, which will alternately relax and tighten the opponensplasty.

Under certain conditions, such as high combined median and ulnar nerve palsies and diseases (e.g., Charcot-Marie-Tooth disease and leprosy), the thumb extensors are strong and unbalanced and the sensory loss is profound; in these conditions the patient may stretch the transfer if the thumb is mobilized in 3 weeks or less. Therefore it is advisable to protect the opponensplasty for 3 months to prevent full adduction, supination, and extension of the thumb.

Author’s Preferred Method of Treatment: Low Median Nerve Palsy

My enthusiasm for reconstructive surgery in median nerve palsy is tempered by the belief that sensation is the prime determinant of hand function in this situation. I thus believe that isolated injuries to the motor branch of the median nerve and focal pure motor deficits caused by nonprogressive or slowly progressive neurologic disease are the best indications for opponensplasty. The more severe the sensory deficit, the less likely the patient is to benefit from reconstructive surgery.

Therefore I believe that opponensplasty is rarely indicated for combined complete median and ulnar nerve injuries in adults because permanent sensory deficit is often severe even after careful nerve repair. In my practice, few patients require or request an opponensplasty after isolated traumatic division of the median nerve; in fact many retain adequate opposition, presumably because of anomalous thenar muscle innervation.

In combined nerve deficits it is imperative that both the patient and the surgeon consider whether the loss of opposition, taken in isolation from the rest of the neurologic deficit, is causing sufficient disability to justify further surgery and rehabilitation. This is especially the case in times of job insecurity and financial uncertainty, when time away from work may result in job loss. Many of my patients, especially those with unilateral loss of opposition, adapt well and minimize their disability so that an opponensplasty is not indicated.

My favored transfers are the Camitz procedure and the EIP transfer. I used to favor the Royle-Thompson superficialis transfer but have converted to the EIP transfer over time. I use the Camitz procedure for patients with loss of opposition secondary to carpal tunnel syndrome and perform this transfer at the same time as carpal tunnel release, even though I believe that thenar muscle function will recover in a considerable number of cases. I do this because the procedure has low morbidity and complication rates and requires little rehabilitation. Also, the recovery of thenar muscle function is unpredictable and may not occur for over a year.

The Camitz procedure does require general or regional anesthesia, whereas most of my carpal tunnel releases are done under local infiltration anesthesia. Restoration of thumb abduction in these patients may produce immediate improvement in hand function if median nerve sensation has not been completely lost and there is a reasonable prospect for sensory recovery.

In other instances, I now favor the EIP transfer, which rarely causes any donor site morbidity, provided that the index finger extensor hood is not damaged. Furthermore, this transfer uses a natural pulley (i.e., ulnar border of the wrist) that is resilient and cannot migrate. In isolated median nerve transfers, this transfer is inserted into the APB tendon. I have not experienced significant loss of thumb extension after this transfer and have found rehabilitation and reeducation straightforward.

With more complex upper limb paralyses, it is important to assess the disability carefully, ascertain which musculotendinous units are available for transfer, and consider the probable effects of loss of the transfer’s normal function before making any decision.

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