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, usually 90 degrees of pronation and 60 degrees of supination, 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 either as a muscle of 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 adductor pollicis 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%, 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 and is exclusively supplied by the ulnar nerve in 19% of them. They also believe that the oblique head of the adductor pollicis 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. Of the patients of Foucher and colleagues with severe carpal tunnel syndrome, 7% had absent or inadequate thumb opposition. All the thenar intrinsic muscles were paralyzed after combined median and ulnar nerve injuries; in this situation, thumb opposition was absent and the patient was 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

Opponensplasty Insertions.

Many insertions have been described ( Figure 31.1 ), including one discussed by Curtis, 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 MP 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 their 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 MP 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.

A-D, Techniques of distal attachment as described by Brand, Littler, Riordan, and Royle-Thompson. AbPB , Abductor pollicis brevis; AdP , Adductor pollicis brevis; EPB , extensor pollicis brevis; EPL , extensor pollicis longus; FDS , flexor digitorum superficialis.

Dual insertions into the APB insertion and either the dorsal MP 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 who regain or never lose good opposition after median nerve repair and loss of thenar muscle function, 66% frequently recover 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 *
Excellent	Opposition to ring or little fingertip with IP joint extended	75% of function of opposite thumb when normal
		or
Good	Opposition to index or middle fingertip with IP joint extended	<20 degrees of difference between the planes of the opposed thumb-nail and the palm with good power
Fair	Thumb IP joint flexes during opposition	Full, though weak, opposition or Restricted, but strong, opposition
		or
Poor	No opposition restored	No opposition restored

 

* 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 ( Figure 31.2 ).

A patient with bilateral T1 neuropathy due to neurological 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 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.
  

  Flexor digitorum superficialis (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.

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.

  
  
• •
  

  Whenever possible, a single insertion of the transferred tendon is preferable.

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 8 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 (50–70 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 ( Figure 31.3 ).

A, B, A poor Bunnell superficialis (flexor digitorum superficialis) transfer. There was no fixed pulley at the pisiform. The transfer has migrated and is now acting more as a flexor of the metacarpophalangeal joint than as a real abductor/opposer. Satisfactory opposition needs a fixed pulley near the pisiform.

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 flexor carpi ulnaris 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’s 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’s 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 MP joint, whereas placing it so that the transfer’s line of pull passes distal to the pisiform produces more thumb MP 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 MP 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 MP 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 MP 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 MP 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 ( Figure 31.4 ) 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.

Extensor indicis proprius (EIP) transfer. A, The tendon is divided and delivered into a large dorsoulnar wrist incision; this may require an additional incision on the dorsum of the hand immediately distal to the extensor retinaculum, where the EIP and index extensor digitorum communis (EDC) tendons can be attached to each other. B, The muscle belly of the EIP is mobilized and placed on the ulnar aspect of the wrist and its tendon is passed through a subcutaneous tunnel around the wrist to an incision over the thumb metacarpophalangeal joint. C, The transfer is then sutured to the abductor pollicis brevis (APB) tendon.

Technique.

A short incision is made over the index finger MP joint, and the EIP tendon is divided immediately proximal to the extensor hood. Some surgeons recommend that a contiguous slip of the extensor hood be harvested with the tendon to lengthen the transfer. However, this is unnecessary, and if the extensor hood is not properly repaired, its radial and ulnar halves may subluxate palmarly and cause an extensor lag. A long incision is then made on the dorsoulnar aspect of the distal forearm, the extensor indicis tendon is delivered into this wound, and its muscle is freed of soft tissue attachments in the distal third of the forearm. It is important to retrieve the tendon proximal to the extensor retinaculum for adequate tendon length and line of pull. Sometimes this is 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.

Next, small incisions are made in the pisiform area and on the dorsoradial aspect of the thumb MP. 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. The extensor indicis tendon is passed through this tunnel while making certain that the tendon goes superficial to the FCU tendon; 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 wrist 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.

In combined median and ulnar nerve palsies with an intrinsic-minus thumb, the transfer is attached in sequence to the APB tendon, the MP 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 MP joint more effectively and substitute for the paralyzed FPB. Postoperatively, the hand is immobilized with the wrist in flexion and the thumb in full opposition 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 workers 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 ( Figure 31.5 ), described independently by Huber and Nicolaysen, was popularized by Littler and Cooley who considered the ADM a close substitute for the APB. This transfer also improves the hand’s appearance by increasing the bulk of the thenar eminence.

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 MP joint. The distal attachment is to the APB muscle. Flex. br. , flexor digiti minimi brevis; P.M. lig. , pisometacarpal ligament.

(From Littler JW, Cooley SGE: Opposition of the thumb and its restoration by abductor digiti quinti transfer. J Bone Joint Surg Am 45:1389–1484, 1963, with permission.)

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 MP 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 Figure 31.5 ).

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, many surgeons retain the pisiform origin and lengthen the transfer with a short tendon graft when necessary.

Others, in complete contrast, have completely released the origin of ADM and left it 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 ( Figure 31.6 ). Many surgeons use the Huber transfer as the opponensplasty of choice in pediatric patients with congenital thenar muscle deficiencies (see Chapter 37 ).

A, B, Huber abductor digiti minimi opponensplasty after satisfactory function has been restored, at least partly because the direction of pull is really from the pisiform.

Palmaris Longus Opponensplasty (Camitz).

The Camitz PL opponensplasty ( Figure 31.7 ) 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, which can be performed under regional anesthesia at the same time as carpal tunnel release, restores palmar abduction rather than opposition. Even though thumb opposition and abduction may recover after carpal tunnel release, this will probably take many months; thus, it is reasonable to perform a Camitz procedure at the same time as carpal tunnel release for patients with severe thenar wasting and functional disability. This transfer is not recommended for traumatic median nerve injuries because the PL, which lies directly over the median nerve, and the overlying skin are usually also scarred and damaged. However, its use has been utilized in this situation in young children.

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

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 starting 2 cm proximal to the distal wrist crease and running to the proximal palmar crease is made 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 palmaris longus tendon is freed up in the forearm and into 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 MP joint. A wide subcutaneous tunnel is then developed between this joint and the distal forearm incision, through which the PL tendon and its aponeurotic extension are passed.

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 MP joint capsule, to increase opposition. Foucher and coworkers favor attachment to either the EPB tendon or the dorsal capsule of the MP 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 MP 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 is then worn for another week.

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 MP joint or the EPB tendon restricted MP joint movement slightly (15–25 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 ( Figure 31.8 ).

A patient presented with longstanding 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.

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.

Other opponensplasties include the ECU, ECRL, and EDM opponensplasties.

ECU Opponensplasty.

The ECU opponensplasty described by Phalen and Miller allows the ECU to be used as an opponensplasty, without the need for a free tendon graft, by incorporating 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 MP 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 insertion. A wide subcutaneous tunnel running from the thumb MP 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.

When harvesting the ECU, care should be taken to identify and preserve the dorsal-ulnar sensory nerve. This tendon is withdrawn back under the extensor retinaculum and freed of soft tissue attachments throughout the distal third of the forearm. It is then passed around the ulnar border of the distal forearm and sutured to the EPB tendon while the thumb is opposed to the base of the middle finger with its MP 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, and in 4 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 MP joint flexion deformity may occur if the EPB tendon is dissected out from the extensor hood right up to its insertion; in contrast, if it is not dissected out sufficiently distally, it can cause MP joint hyperextension. Third, a tendinous slip sometimes connects the EPB and EPL tendons; if this is present, it must be divided because the transfer may otherwise cause unwanted extension of the IP joint.

ECRL Opponensplasty.

The tendon of the ECRL muscle can be lengthened 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 carefully split in half longitudinally, such that one strip remains attached to the 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 tendon. Next, the transfer is passed through a wide subcutaneous tunnel around the ulna, just proximal to the pisiform, and inserted into the APB attachment and EPL. Alternatively, Kaplan and coworkers elongated the ECRL tendon with the EPL tendon for four patients with isolated median or combined median and ulnar nerve injuries.

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 MP 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, where it is 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.

In Kaplan and coworkers’ small series, all thumbs regained abduction and opposition and thumb IP joint flexion and extension were preserved. Henderson also used the ECRL in five patients, all of whom regained satisfactory opposition. Baek and colleagues who prefer this transfer to the use of the EIP, which they consider allows only weak opposition, achieved excellent results in 10 of 11 cases.

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 MP 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 slip of the extensor hood are freed distally and withdrawn proximally into a large 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 outside of the extensor retinaculum, around the ulnar border of the wrist, and subcutaneously across the palm by using the technique described for EIP transfer. In the original description of this transfer, it 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 ( Figure 31.9 ). The donor tendon is not long enough on its own, so a portion of the extensor hood must be taken to ensure adequate length. Despite careful repair of the hood, this author encountered extension lag of the little finger after the transfer.

EDM transfer for opposition of the thumb. Note the position at the time of surgery (A) and postoperative active abduction and rotation of the thumb (B, C), even with an immobile wrist.

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 MP joint to extend. 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 ( Figure 31.10 ). 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 Figure 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.

With hyperflexion of the interphalangeal joint, a moment for supination of the thumb occurs if the index finger contacts the thumb with power. Brand calls this the crank-handle effect.

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 and thumb joint fusion or, less commonly, 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.

The distal attachment of the 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 at its insertion to expose the IP joint that is fused in extension. 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 through a further incision 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.

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 MP 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 MP 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 ( Figure 31.11 ). After this transfer, the patient uses the EPL to move the thumb away from the fingers and the FPL opponensplasty for prehension activity.

Flexor pollicis longus (FPL) opponensplasty. A, B, A 25-year-old man presented with a brachial plexus injury and the equivalent of an intrinsic-minus thumb. The thumb extrinsic muscles were causing metacarpophalangeal joint extension and interphalangeal (IP) joint hyperflexion. An FPL opponensplasty and thumb IP arthrodesis restored short thumb flexor and extensor pollicis longus (EPL) function. C – E, Improved thumb function was apparent as soon as the cast was removed. The EPL now functions not as an adductor but as an extensor, and the FPL now functions as a short flexor replacement. The pulley for the transfer was at the pisiform, and its distal attachment was the abductor pollicis brevis tendon.

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 MP joint ( Figure 31.12 ). 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 MP joint, which was then fused. They stressed that the transfer must pass over the extensor surface of the MP joint and not over the dorsum of the proximal phalanx, which can cause a flexion deformity of the MP joint ( Figure 31.13 ). These authors recommended this transfer for completely intrinsic-minus thumbs in high nerve injuries but favored EIP opponensplasty and MP joint arthrodesis if there were no fixed deformity of the IP joint.

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 until union.

(Redrawn from Makin M: Translocation of the flexor pollicis longus tendon to restore opposition. J Bone Joint Surg Br 49B:458–461, 1967, with permission.)

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 (MP) 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 MP joint before passing radially over the neck of the metacarpal. C, The MP 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 MP 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 MP joint. If it passes over the back of the proximal phalanx, it may flex the MP 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 MP 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 ( Figure 31.14 ) 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.

Extensor pollicis brevis (EPL) opponensplasty. A, B, The middle portion of the EPL tendon is exposed over the proximal phalanx and removed in continuity with the main EPL tendon proximal to the metacarpophalangeal (MP) joint. C-E, The transfer is then passed around the ulnar border of the wrist, and the thumb MP joint is fused. F, The two lateral portions of the EPL tendon over the proximal phalanx are sutured together, and the transfer is sutured around them. The interphalangeal joint is temporarily pinned in extension to protect the transfer while it heals.

(From Riley WB, Mann RJ. Burkhalter WE: Extensor pollicis longus opponensplasty. J Hand Surg 5:217–220, 1980, with permission.)

Technique.

An incision is made on the extensor surface of the proximal phalanx and MP joint of the thumb. The EPL tendon, with a contiguous central portion of the extensor expansion, is then freed from its insertion on the distal phalanx while preserving the lateral portions of the extensor hood over the proximal phalanx and the MP joint. 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 MP joint is fused in almost full extension and some pronation ( Figures 31.15 and 31.16 ).

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 Figure 31.10 , but with an even longer moment arm.

A, B, A completely intrinsic-minus thumb in which only a single motor was used to reconstruct function. In spite of adequate release (C), this patient needs either a metacarpophalangeal (MP) joint arthrodesis in full extension or a second transfer to restore short flexor–adductor function. As the patient attempts to pinch the thumb and the index finger together (D), thumb MP joint flexion produces a tremendous crank-handle action.

The transferred EPL tendon is then looped around the lateral portions of the extensor hood at the level of the MP 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. 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 MP 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 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 ( Figure 31.17 ). However, all the patients had a diminished range of retroposition.

This patient with Charcot-Marie-Tooth disease has undergone arthrodesis of the thumb metacarpophalangeal (MP) joint as well as an extensor pollicis longus opponensplasty. A, The abductor pollicis longus can move the thumb clear of the fingers so that it does not interfere with power grip. B, In addition, notice that the MP joint of the left thumb has been arthrodesed in hyperpronation, whereas on the right it has been fused in an almost neutral position. The crank-handle effect is much less obvious in the left thumb, which suggests that fusion of the MP joint in hyperpronation, as well as full extension, is preferable for patients with combined median and ulnar nerve palsy.

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 never lose 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 was converted to the EIP transfer by the papers of Burkhalter, who wrote previous editions of this chapter, and discussions with Nicholas Barton, coauthor for the fourth edition of this chapter. 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 regeneration.

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.

Expectations and Patient Counseling for Low Median Nerve Palsy

What I tell the patient about the expected outcome depends on (1) whether the underlying neurologic pathology is progressive (progressive neurologic disease) or static (nerve injury after regeneration period); (2) the functional disability attributable to the isolated loss of opposition; and (3) the functional disability attributable to other problems in the hand, such as sensory loss, and loss of other motor functions. This author would advise a motivated patient with an otherwise normal hand (e.g., isolated injury to the motor branch of the median nerve) that restoration of opposition with either an EIP, FDS, or ADM transfer should restore useful opposition and improve hand function considerably in 7 or 8 of every 10 cases. I tell patients with loss of opposition due to severe carpal tunnel syndrome that they will regain thumb abduction in a similar number of instances but that the functional benefit of this depends to a great extent on the recovery of lost sensation in the thumb and index and middle fingers after the carpal tunnel release.

For more complex cases, such as loss of opposition after combined median and ulnar nerve injuries, I tell patients that opposition can be restored in 7 or 8 of every 10 cases; however, I stress that their loss of opposition is (usually) only causing a small amount of their total hand disability and that they may not gain any significant functional benefit from a successful opponensplasty. In my opinion, before recommending surgery, there has to be convincing evidence that the loss of opposition, rather than loss of sensation or other motor deficits, is causing loss of function.

When dealing with progressive neurologic disease, it is vital to have the opinion of the treating neurologist regarding the likely course and speed of progression of the condition and to be aware of whether the deficit is and/or will be purely motor or combined sensory and motor. I then carefully discuss the likely short- and long-term benefits of an opponensplasty with the patient so that he or she can make an informed decision on its probable impact on hand function ( Table 31.3 ).

Timing and Selection of Extrinsic and Intrinsic Transfers

The selection and timing of tendon transfers for both intrinsic and extrinsic paralysis in high median nerve lesions depend on the prognosis for the median nerve injury, as well as the surgeon’s assessment and the patient’s perception of the functional disability.

In patients with median nerve palsy, the sensory loss is probably the most important single disability and, if permanent, dramatically reduces the functional benefit of tendon transfers, particularly for restoration of opposition. Although some surgeons believe that severe sensory loss, which is likely to be permanent in an adult, is a strong contraindication to tendon transfers, others argue that eyesight can provide sensory input and some hand function remains. Therefore, they believe that a mobile, opposable thumb is probably more useful than one that cannot reach the remaining areas of the hand with normal sensation.

The functional deficit associated with a high median lesion is so profound that some surgeons advocate early end-to-side tendon transfers for selected patients to restore either opposition alone or opposition and extrinsic muscle function. These early transfers maintain motor function during nerve regeneration and act as an internal splint, thereby preventing contractures and eliminating the need for cumbersome external splints that may severely limit patients’ ability to use the hand. If patients ultimately regain some function in the muscles involved, the transfers act in synergy and provide additional power, whereas if no recovery occurs, the transfers act as a permanent substitute.

Extrinsic Transfers

Good extrinsic muscle function is usually restored after repair of a high median nerve laceration, in which case transfers to restore flexion of the thumb and index finger are not required. However, these should be considered if there is no evidence of extrinsic muscle recovery several months after a nerve repair. For practical purposes, extrinsic tendon transfers are indicated only when a high median nerve injury is not repaired or is grafted. If one decides not to perform early extrinsic tendon transfers, it is essential that mobility of the thumb and index finger are maintained until recovery occurs.

Restoration of Thumb Opposition

As previously mentioned, many patients retain thumb opposition after median nerve injury and do not require an opposition transfer. Burkhalter, who had a wealth of expertise and wrote this chapter for previous editions, believed that those who lost opposition should undergo an opposition transfer soon after neurorrhaphy or grafting and before sensory recovery. His rationale was that the likelihood of recovery of thumb intrinsic muscle function after high median nerve injury is low.

Another reason to pursue early opponensplasty is to allow the patient to pick up objects with the forearm in any position of rotation. Patients who have lost thumb opposition and abduction use the APL and the extrinsic extensor muscles to position their thumb when picking up an article from a table. Although the thumb–index web is open, the thumb is supinated and extended because all the muscles are supinators. With the thumb in this position, the patient can pick up objects from a flat surface only by fully pronating the hand, either by pronating the forearm or internally rotating the shoulder (see Figure 31.2 ). Thus, the patient cannot see the palm of the hand and cannot use sight as a substitute for the median nerve sensory loss, which renders motor function of little use to the person. If a patient is able to use a paralyzed hand to pick up articles and transfer objects from hand to hand in a position other than full pronation, the FPB is probably still functioning and an opponensplasty is not needed.

Restoration of Opposition in High Median Nerve Palsy

In high median nerve palsy, the EPL, EIP, and EDM are most readily available for opposition transfer. They position the thumb well, do not create significant donor morbidity, and do not require lengthening with a tendon graft. Although strong opposition can be restored with the FCU, which may be elongated with a paralyzed superficialis tendon, this is not advised because it eliminates the only functioning wrist flexor. Moreover, strong thumb opposition is not required as long as there are functioning intrinsic muscles capable of acting as a short flexor or short flexor substitute.

Brachioradialis-to-FPL Transfer

To achieve 30-mm excursion, the brachioradialis muscle must be freed of all soft tissue and fascial attachments throughout the distal two-thirds of the forearm. This involves dissection well proximal to the musculotendinous junction because the peripheral fibers of this muscle are inserted onto the deep fascia of the forearm. The transfer’s tension is set so that all three thumb joints can be fully passively extended when the wrist is flexed 30 degrees; again, and for the same reason mentioned for the ECRL-to-index profundus transfer, excessive tension must be avoided. Because the brachioradialis originates above it, the elbow is placed in approximately 45 degrees of flexion during tensioning. Although this degree of tension does not allow full IP joint flexion, it stabilizes it, improves thumb strength, and prevents a disabling flexion contracture from developing ( Figure 31.18 ). Most precision pinch activities are performed with the thumb IP joint fully extended.

Extrinsic reconstruction using brachioradialis-to-flexor pollicis longus (A) and extensor carpi radialis longus-to-index and long finger profundi (B) transfers. The transfers shown here are end-to-end but should be done in an end-to-side fashion if there is to be any chance of recovery.

Because the prime function of the brachioradialis is elbow flexion, its usefulness as a transfer depends on elbow position. When the elbow is extended, reasonably powerful thumb flexion is usually provided, but thumb flexion is much weaker when the elbow is flexed. For this reason Brand and others have considered fixing the brachioradialis origin distal to the elbow ; however, this practice is not widely performed.

ECRL-to-Index Profundus Transfer

An ECRL-to-index profundus transfer ( Figure 31.19 ) is performed only in patients who need additional strength on the radial side of the hand and are unlikely to obtain significant reinnervation after nerve repair. Usually, index finger range of flexion, but not strength, is restored by side-to-side suturing of the index and the conjoint middle, ring, and little fingers’ profundus tendons in the distal forearm. If an ECRL transfer is indicated, its tension is adjusted so that the finger is virtually fully extended when the wrist is flexed 30 degrees and is fully flexed when the wrist is extended 30 to 45 degrees. If this transfer is placed in excessive tension, flexion contractures can result and cause considerable disability.

High median nerve palsy treated with brachioradialis-to-flexor pollicis longus (FPL) and extensor carpi radialis longus-to-index finger profundus tendon transfers. A, B, There is good FPL power but a limited range of active interphalangeal joint flexion when the wrist is held still. C, Note the absence of either thumb or index finger flexion contractures.

Complications

Swan-neck deformities can develop in patients with hyperextensible PIP joints after high median paralysis due to unopposed intrinsic action on the PIP joint with paralysis of the FDS. The deformity develops gradually as the PIP palmar plates stretch and may cause disability with locking of these joints in extension.

High Median Nerve Palsy Summary

In a high median nerve injury, the surgeon should consider performing an opposition transfer if forearm pronation is used as a substitute motion. If the nerve has been repaired, extrinsic transfers are seldom required because satisfactory extrinsic muscle function is usually regained. If the patient needs a nerve graft, especially if this is done late or under unfavorable conditions (e.g., a long graft or a poor bed), useful extrinsic functional recovery is unlikely and one should consider performing early extrinsic end-to-side transfers and/or a side-to-side transfer of the index and conjoint profundus tendons. All these intrinsic and extrinsic transfers can be performed at the same time.

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

Again, my enthusiasm for reconstructive surgery is tempered by the belief that sensation is the prime determinant of hand function and because I believe that sensory recovery after a high median nerve repair in adults is always poor and is even worse if a nerve graft is required. Furthermore, I believe that nerve repair hardly ever restores lost opposition, although useful reinnervation of the forearm flexor muscles undoubtedly occurs. For these reasons, I do not favor early extrinsic tendon transfers and only restore opposition if, after maximal recovery has occurred, both the patient and the surgeon believe that this will improve hand function. Most patients will adapt and increasingly use their normal arm (even if this is the nondominant arm) for precision function; I thus rarely attempt to restore opposition when there is a combined median sensory and motor deficit. If an opposition transfer is indicated, I favor EIP transfer.

I use the brachioradialis transfer for restoration of thumb flexion, especially for conditions in which there is relative sensory sparing, and use an end-to-side attachment unless there is no prospect of later reinnervation. I do not believe that an ECRL transfer to restore index finger flexion is needed often and prefer to join the index and the common (i.e., middle, ring, and little) profundi tendons in a side-to-side fashion. Although this does not restore power to the index finger, I believe that the condition of the hand is usually too poor to benefit from an ECRL transfer, especially if there is a marked sensory deficit.

Expectations and Patient Counseling for High Median Nerve Palsy

It is imperative to stress to adult patients with high median nerve damage that they have suffered a severe injury and will never regain normal hand sensation, strength, or function. They should be aware that the aim of all surgery is to create the best possible “helper” hand, although this will always have rudimentary function when compared with their normal contralateral one. The author thus does not enthusiastically recommend opponensplasty in the presence of severe sensory loss in the median nerve distribution because most patients will use their other hand for fine-pinching tasks, even after a “successful” opponensplasty. In contrast, I do recommend tendon transfers for persistent loss of the thumb and finger extrinsic flexor function. However, it is important to stress that restored thumb and finger flexion will be weak, although with sensory input provided by the eyes, it should allow rudimentary use of the hand to hold and steady light objects.

High Median Nerve Palsy Summary

Tendon transfers ( Table 31.4 ) can restore selected motor functions as a result of high and low median nerve palsy, but their ability to improve function is restricted by the severity of any associated sensory loss. Numerous opposition transfers have been described, and almost every possible motor has been used. Many pulleys are available, and there are numerous methods of distal attachment. The main reasons for failure of opposition transfers are persistent thumb contractures (recognized or unrecognized) and selection of a less than adequate motor. Early opposition transfer has been recommended for patients who use forearm pronation as a substitute for the paralyzed APB. Extrinsic tendon transfers for high median nerve palsy are usually required only when the injury is bridged with a nerve graft or left untreated.

Low Ulnar Nerve Palsy

Clawing of the fingers in ulnar nerve palsy is due to the combined paralysis of the interosseous muscles of all the fingers and the lumbricals of the ring and little fingers. These intrinsic muscles flex the MP and extend the PIP and DIP joints of the fingers; loss of their resting tone results in the “intrinsic minus” posture of hyperextension at the MP joints and flexion at the IP joints. Clawing due to isolated ulnar nerve disease is most marked in the ring and little fingers whose interossei and lumbricals are all paralyzed; it occurs, however, in all four fingers in 63% of cases as a result of Hansen disease, even though the index and middle finger lumbricals are innervated by the median nerve. Clawing is more apparent during use of the hand than when it is at rest. Marked clawing of the fingers occurs most commonly in those with mobile, lax finger joints and is less common in those with stiffer fingers (e.g., Caucasian manual laborers).

In addition to the static-claw deformity, loss of intrinsic muscle function can affect the normal dynamics of finger movement. In a normal hand the MP joints flex before the IP joints when gripping an object, such that the object is drawn into the palm of the hand. In ulnar paralysis, however, the distal interphalangeal joints flex first, followed by the PIP joints and then the MP joints, such that the object is not guided into the palm, but instead is pushed out of the palm by the fingertips.

When assessing an ulnar claw hand, it is important to ascertain whether all the finger joints have a full range of active and passive movement and whether correction of the hyperextension at the metacarpophalangeal joints results in full extension of the IP joints (the Bouvier maneuver). If this is the case, then operations that address the MP joint hyperextension (i.e., capsulodesis or tenodesis of the MP joint or Zancolli-type tendon transfers) should completely correct the deformity. If the PIP joints remain flexed when the MP joint hyperextension is corrected, but can be passively fully extended, then a static procedure will not correct IP joint flexion; thus, a tendon transfer is needed in order to provide a flexion force at the MP joints and an extension force at the PIP joints. However, with claw hands that have been present for a long time, the dorsal transverse retinacular fibers of the extensor mechanism, which normally prevent palmar migration of the lateral bands, may stretch; this allows the lateral bands to migrate palmar to the axis of rotation of the PIP joint and become flexors, rather than extensors, of these joints.

A secondary hyperextension deformity of the DIP joint may then occur, as with a Boutonnière deformity. In this situation the lateral bands need to be reconstructed such that they pass dorsal to the axis of rotation of the proximal interphalangeal joint. Failure to do this before performing a tendon transfer into the lateral bands will exacerbate rather than improve the deformity. If there are fixed-flexion deformities of the IP joints, then these need to be corrected before surgery.

Outcome of Surgery Assessments

Assessment of the outcome of procedures for ulnar nerve palsy should be done at no less than 6 months follow-up. Even then the comparison of the reported outcomes of various procedures to correct clawing of the fingers is difficult due to the heterogenicity of patient profiles in studies. Factors include the etiology of the ulnar nerve palsy (i.e., static or progressive), the level of the lesion (i.e., high or low), the presence of an isolated ulnar or combined median and ulnar nerve palsy, the presence or absence of joint contractures, and differences in patients’ overall joint mobility.

Careful review of the operative techniques used by various authors demonstrates that few surgeons use exactly the same surgical techniques and rehabilitation programs (e.g., one, two, or four tendons may be used for the FDS transfer, with the number varying from patient to patient in some studies). Finally, the movement and function being restored are complex, and different authors have used a variety of techniques for assessing the outcomes of their procedures. To my knowledge only one study has assessed the outcomes of these operations with a validated hand function assessment (e.g., Jebsen functional examination or the Purdue pegboard ), and none has used an outcome questionnaire such as the DASH ( Table 31.5 ).

TABLE 31.5

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