27: Flexor Carpi Ulnaris–to–Extensor Carpi Radialis Brevis Transfer

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Procedure 27 Flexor Carpi Ulnaris–to–Extensor Carpi Radialis Brevis Transfer

Sandeep J. Sebastin, Kevin C. Chung

Indications

Cerebral palsy patient with a hyperactive flexor carpi ulnaris (FCU) and weak or absent wrist extension

Late presentation of neonatal brachial plexus palsy with an ulnar deviation deformity and absent wrist extension

Examination/Imaging

Clinical Examination

Cerebral palsy: The flexion deformity in cerebral palsy can be due to spasticity of the wrist flexors, weak wrist extensors, and/or a volar wrist capsular contracture. It is important to differentiate among these causes. An attempt at overcoming muscle spasticity should be done by applying gentle sustained resistance to the spastic force. If the wrist can be extended passively, it rules out capsular contracture. If the wrist cannot be extended passively, but the wrist flexors do not feel spastic, it suggests a wrist capsular contracture. If the spasticity cannot be overcome, a median and ulnar nerve block at the elbow can temporarily eliminate the flexor spasticity and allow an assessment of active and passive wrist extension. An FCU-to–extensor carpi radialis brevis (ECRB) transfer is indicated in patients who have a spastic FCU and good passive wrist extension (no capsular contracture) but lack active wrist extension. Before considering an FCU-to-ECRB transfer, one must ensure that the patient has the following:

• A functioning FCR, or the transfer will result in a wrist extension deformity

• Active digital extension with the wrist held in slight extension. If there is some active digital extension, but it is limited by the tight digit flexors owing to the wrist extension, a concomitant lengthening of the digital flexors will be required (Fig. 27-1). If there is no active digital extension, the patient will need lengthening of the digital flexors and augmentation of digital extension with a long finger FDS-to-EDC transfer.

Neonatal brachial plexus palsy (NBPP): The ulnar deviation deformity in this group of patients can be due to the FCU or the extensor carpi ulnaris (ECU). Either one of these tendons can be used for obtaining wrist extension depending on the predominant cause of the ulnar deviation deformity. In NBPP, the FCU is passed around the radius to the extensor carpi radialis longus (ECRL) to get some radial balance to the hand at the wrist. In cerebral palsy, the transfer is made around the ulna to the ECRB. This chapter describes the procedure in cerebral palsy.

FIGURE 27-1

Surgical Anatomy

The purely tendinous portion of the FCU is quite short as the muscle extends distally along the tendon. In addition, the muscle is attached along the ulna over a long distance. The muscle must be detached quite proximally to have adequate excursion of the transferred FCU (Fig. 27-2).

The ulnar artery and nerve are very closely related to the undersurface of the FCU and must be protected during mobilization of the FCU (Fig. 27-3).

FIGURE 27-2

FIGURE 27-3

Positioning

The patient is placed in the supine position, and the operation is performed under tourniquet control.

Exposures

A 4-cm longitudinal incision over the volar forearm extending proximally from the pisiform is made, in line with the palpable FCU tendon (Fig. 27-4). Skin and subcutaneous tissue are dissected, and the FCU tendon is exposed.

A 6-cm longitudinal incision over the dorsal forearm extending proximally from the base of the long finger metacarpal is made (Fig. 27-5). Skin and subcutaneous tissue are dissected to expose the extensor retinaculum. The second dorsal extensor compartment is opened, and the tendons of the ECRL and ECRB are identified.

FIGURE 27-4

FIGURE 27-5

Pitfalls

One must watch out for branches of the superficial radial sensory nerve during exposure of the ECRB.

Procedure

Step 1

The FCU is detached from its insertion on the pisiform and dissected as proximally as possible to release all the fascia attachments to the ulna so that the muscle has adequate excursion (Fig. 27-6).

FIGURE 27-6

Step 1 Pearls

The ulnar neurovascular bundle, which is under the FCU, must be preserved. Typically, there is a fascial layer covering the neurovascular bundle that should not be disturbed.

Step 2

The FCU tendon is passed around the ulnar aspect of the forearm, over the skin, to the point where it intersects with the ECRB. The route of the FCU tendon is marked.

A wide subcutaneous tunnel is made along the route from the dorsal incision to the volar incision, and the FCU tendon is delivered in the dorsal wound.

Step 2 Pearls

It is important to make the subcutaneous tunnel along the shortest, most direct route between these two tendons. Otherwise, the transferred tendon will move over time into the shortest route. This will make the transferred tendon lax and less effective.

The tendon is passed superficial to the extensor tendons of the first and third compartments (adductor pollicis longus [APL], extensor pollicis brevis [EPB], and extensor pollicis longus [EPL]) (Fig. 27-7).

FIGURE 27-7

Step 3

The FCU tendon is weaved into the ECRB tendon using the Pulvertaft weave with 3-0 Ethibond suture (Fig. 27-8A and B).

The tension is set with the wrist in neutral or 30 degrees of flexion. One must not overtighten the transfer to achieve wrist extension beyond neutral because the patient typically does not have sufficiently strong finger extensors to extend the fingers and will rely on tenodesis effect with the wrist in flexion to extend the fingers (Fig. 27-9).

FIGURE 27-8

FIGURE 27-9

Step 3 Pearls

It is not necessary to divide the ECRB tendon, given that this tendon may still be innervated and partially functional.

The tendon weave should be done such that the weave does not encroach on the intersection with the APL and EPB during wrist extension.

Step 3 Pitfalls

If passive flexion of the wrist to 20 degrees is not possible, the tendon repair is too tight and should be loosened.

Step 4

The tourniquet is released, hemostasis is secured, and the incisions are closed in layers.

Postoperative Care and Expected Outcomes

The patient’s wrist is splinted in neutral position for 4 weeks, followed by range-of-motion exercises. The patient wears a removable splint for an additional 4 weeks. Most patients can extend the wrist actively, but if spasticity is not controlled, they may develop recurrent wrist contracture. These patients are advised to wear a volar wrist extension splint at night.

This transfer has shown good results with improvements in resting wrist posture and arc of wrist motion. However, it is associated with a loss in wrist flexion, and the range of motion usually remains unchanged.

Thometz JG, Tachdjian M. Long-term follow-up of the flexor carpi ulnaris transfer in spastic hemiplegic children. J Pediatr Orthop. 1988;8:407-412.

This report is a retrospective study of 25 cerebral palsy patients who underwent FCU transfer to the wrist extensors. The mean follow-up period was 8 years and 1 month. The mean active wrist extension was 44.2 degrees, and the mean flexion was 19.0 degrees. The patients had an effective result except for loss of flexion of the wrist after the operation. (Level IV evidence)

Tonkin M, Gschwind C. Surgery for cerebral palsy. Part 2: flexion deformity of the wrist and fingers. J Hand Surg [Am]. 1992;17:396-400.

The authors performed flexor aponeurotic release, FCU tenotomy, FCU-to–extensor carpi radialis transfer, flexor pronator slide, and proximal row carpectomy in 34 patients with cerebral palsy. They reported that 30 patients were improved functionally and cosmetically. (Level IV evidence)

Wolf TM, Clinkscales CM, Hamlin C. Flexor carpi ulnaris tendon transfer in cerebral palsy. J Hand Surg [Am]. 1998;23:340-343.

In this retrospective study, 16 patients participated in comparison of wrist position, analysis of outcome predictors, and subjective and objective assessment of function after FCU transfer to relieve flexion contracture of the wrist in cerebral palsy. The average follow-up was 4 years; the patients showed improvement in the general resting position, and the center of the arc of motion averaged 6 degrees of pronation and 9 degrees of extension. The authors noted that the most important factor determining the outcome of the operation was the ability of the patient to achieve finger extension. (Level IV evidence)

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Operative Techniques Hand and Wrist Surgery