Chapter 50

Transfer of Flexor Carpi Ulnaris for Wrist Flexion Deformity

Ann E. Van Heest

DEFINITION

• Cerebral palsy is a primary central nervous system dysfunction that leads to significant functional impairment owing to its secondary peripheral manifestations in the upper extremity.

• The upper motor neuron lesion in the brain leads to loss of normal inhibition of tone (ie, spasticity), loss of motor control in the limb (ie, weakness), or impaired coordination of muscle activity (ie, athetosis).

  • The most common manifestation is spasticity.

  • Spastic hemiplegia is the main type of cerebral palsy for which upper extremity surgery is indicated.

• In spastic hemiplegia due to cerebral palsy, the most common peripheral manifestations in the upper limb are shoulder internal rotation, elbow flexion, forearm pronation, wrist flexion and ulnar deviation, finger clenching or swan-necking, and thumb-in-palm deformity.

  • Increased muscle spasticity causes muscle imbalance across joints, which leads to impaired function and over time can lead to joint contractures with skeletal deformation.

  • The wrist is the most commonly affected joint and will be the focus of this chapter.

     

    ANATOMY

• Five primary wrist motors control wrist joint position.

• The three wrist extensor muscles are the extensor carpi radialis brevis (ECRB), the extensor carpi radialis longus (ECRL), and the extensor carpi ulnaris muscles (ECU).

• The two wrist flexor muscles are the flexor carpi radialis (FCR) and the flexor carpi ulnaris (FCU).

• The finger and thumb flexor muscles (flexor digitorum pro-fundus [FDP], flexor digitorum superficialis [FDS], and flexor pollicis longus [FPL]) cross the wrist joint and exert a wrist flexion force. The finger and thumb extensor muscles (extensor pollicis longus [EPL], extensor indicis proprius [EIP], extensor digitorum communis [EDC], and extensor digiti quinti [EDQ]) also cross the wrist joint and exert a wrist extension force.

• Each of the muscles that crosses the wrist joint exerts a vector force for wrist extension and flexion, as well as radial and ulnar deviation.3 These vector force graphs can be used to help determine which muscles are the major deforming force for wrist flexion posturing.

• In cerebral palsy, the most common deformity is wrist flexion associated with ulnar deviation.

  • The muscle with the greatest flexion and ulnar deviation vector is the FCU.

  • The FCU is most commonly the deforming force, particularly because it may be coupled with a weak wrist extensor–radial deviator (ECRL and ECRB).

     

    PATHOGENESIS

• In the early stages of spastic hemiplegia, the joints and muscles will be supple, with full passive range of motion.

• With skeletal growth, the muscle imbalance across joints over time leads to muscle–tendon unit shortening and joint contractures, eventually leading to skeletal deformity.

• Increased FCU tone overpowers the decreased strength of the ECRL and ECRB, leading to a wrist flexion posture.

  NATURAL HISTORY

• In spastic hemiplegia due to cerebral palsy, the FCU is the most common deforming force, pulling the wrist into flexion and ulnar deviation.

  • Over time, the overpull of the FCU leads to contracture of the muscle, which may lead to fixed contracture of the wrist joint.

  • Ultimately, a fixed skeletal deformity can occur by the time of skeletal maturity.

  • Initial management involves exercises to keep the FCU stretched and to prevent contracture of the muscle.

• If muscle contractures develop, splinting may be necessary to prevent worsening of wrist joint contractures.

• Tendon transfer surgery is best performed before fixed contractures develop.

• If fixed joint contractures and muscle contractures exist, a salvage procedure with muscle lengthenings, wrist fusion, or both may be necessary.

  PATIENT HISTORY AND PHYSICAL FINDINGS

• Patient evaluation begins with interviewing the parents regarding use of the affected limb.

• Most commonly, children with spastic hemiplegia will show premature hand dominance, favoring the unaffected side even as young as 6 months of age.

  • This may be the presenting complaint leading to the diagnosis of cerebral palsy.

• Delay of normal pinch-and-grasp function patterning at 1 year of age is evident.

• Generalized patterns of upper extremity use for activities of daily living, commensurate with the child’s age, are discussed with the parents and child. The clinician also observes for bimanual skills such as doing zippers and buttons, cutting food, and tying shoes.

• The child’s functional use of the hand can be quantified using House’s classification of upper extremity functional use:

  • In this nine-level classification, functional use is assessed as follows: does not use, passive assist (poor, fair, good), active assist (poor, fair, good), and spontaneous use (partial, complete).

  • This provides a baseline that the physician can use to help communicate the functional goals of treatment with the parents.

  • Agreement with the parents on the child’s present overall level of limb function serves as a baseline for comparing the outcome of treatment.

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• Examinations and tests to perform include:

  • Passive range of motion of each joint. If a joint is passively stiff, a joint contracture exists. Tendon transfer surgery is best performed in patients with full passive mobility of all joints.

  • Volkmann angle test. This test indicates muscle contracture, as the finger flexors are biarticular, crossing both the wrist joint and the finger joints.

  • Active range of motion of the wrist. This indicates whether this patient has control to be able to actively extend the wrist. If this is absent, a tendon transfer surgery may be indicated to provide better active wrist extension.

  • Active range of motion of the fingers with the wrist held in a neutral position. This test indicates whether a wrist extensor tendon transfer surgery would be helpful. If the patient has better digital control with the wrist in an extended position, then a wrist extensor tendon transfer surgery would be helpful. If the patient has no digital extension, then an FCU tendon transfer should be considered to the EDC. If the patient develops a clenched fist with wrist neutral position, then a wrist extensor tendon transfer would be contraindicated.

  • If a patient has full passive mobility of the joints and no muscle contractures of the finger flexors but positions the wrist in significant flexion, leading to impairment with grasp and release or fine motor tasks, then a wrist extensor tendon transfer surgery to improve wrist position would be indicated.

  • Stereognosis testing. Impaired stereognosis does not preclude surgical intervention, but it is important to identify it preoperatively as a part of the disability present.

     

    IMAGING AND OTHER DIAGNOSTIC STUDIES

• Motion laboratory analysis has been used to assist in determining the position of the joints of the upper extremity during tasks.

• A fine-needle electrode can be used to determine whether phasic control of the muscle occurs during grasp and release.

  • A muscle that is well controlled with phasic activity, without significant or continuous spasticity, is the best candidate for muscle–tendon transfer surgery.5

    DIFFERENTIAL DIAGNOSIS

• Wrist flexion posturing due to ineffective wrist extensors, flexor contracture or spasticity, or wrist or carpal abnormalities.

  NONOPERATIVE MANAGEMENT

• Occupational therapy includes the use of splints, stretching and strengthening programs, and active functional use activities.

• Two types of splints can be used: nighttime serial static splinting for treatment of muscle or joint contractures, and daytime splints for pre-positioning the hand to improve active function.

  • The indication for nighttime splinting is contractures.

    • If no contractures of the muscles or joints exist, nighttime splinting is not necessary and is a waste of time and money for the child and family!

    • If contractures exist at the wrist or fingers and thumb, a nighttime forearm-based wrist–hand orthosis is indicated.

  • Daytime splints are usually used to pre-position the wrist in a neutral to slight “cock-up” position to help improve grasp and to pre-position the thumb out of the palm to help improve pinch.

    • If the splint is bulky or cumbersome, it will interfere with rather than enhance function, defeating its purpose.

    • Care should be given to ensure proper fit of the splint so that its purpose can be achieved.

    • Stretching and strengthening programs, along with active functional use activities, are carried out by the therapist as well as taught to the parents and child as a home program.

• For patients with more focal muscle tone imbalance, botulinum toxin type A injections have been shown to be effective in reducing spasticity in the muscles injected and in improving hand function.1,8,9

  • Botulinum toxin locally blocks the release of acetylcholine at the neuromuscular junction, with a reversible action lasting on average 3 to 4 months. During this period, antagonist muscles can be strengthened and spastic muscles can be stretched, with the benefits lasting beyond the direct effects of the medication.

  • For the mildly involved child, treatment with Botox injections may obviate the need for surgical intervention.

    SURGICAL MANAGEMENT

• The most common deformity of the wrist is flexion, often with ulnar deviation as well. This is the most functionally disabling deformity in hemiplegia as it significantly interferes with grasp and release function.

  • Several surgical options exist, with the choice depending on the degree of deformity and the extent of volitional control of each muscle involved.

• The three main options for treatment of a wrist flexion deformity are:

  • Release or lengthening of the deforming spastic muscles (FCU, FCR)

  • Transfer of tendons to augment the weak wrist extension

  • Wrist fusion to stabilize the joint for the severe, fixed, nonfunctioning wrist

• If the wrist flexor deformity is significant and the patient does not have active control of wrist extension, then tendon transfer surgery to augment wrist extension may be necessary.

  • Using the FCU as a transfer to wrist extension has the advantage of removing its force as a spastic wrist flexor and ulnar deviator, and transferring its forces into wrist extension.

  • Care must be taken to prevent overcorrection if the deformity is not severe, or if the transfer is tensioned too tightly, particularly in the younger child.

    Preoperative Planning

• In all cases of transfer into the wrist extensors, the finger function must be assessed preoperatively with the wrist in neutral, the desired postoperative position.

• If the finger flexors are too tight when the wrist is brought into neutral, a finger flexor lengthening will be necessary as part of the procedure.

   

  • If the patient does not have finger extensor control to allow for release of grasped objects, then a transfer into the finger extensors (EDC) may be indicated.

    Positioning

  • The patient is positioned supine on the operating room table, with an armboard to support the upper limb during the procedure (FIG 1).

  • A tourniquet is applied above the elbow.

    Approach

  • A volar–ulnar approach to the forearm is used to harvest the FCU tendon, and a dorsal approach to the distal forearm and wrist is used for inserting the tendon transfer.

     

     

     

     

    FIG 1 • The patient is positioned supine on the operating room table with the arm extended on an armboard. A tourniquet is applied proximally on the arm.

     

     

    TECHNIQUES

     

    MOBILIZATION OF THE FLEXOR CARPI ULNARIS

  • The incision for exposure of the FCU is a longitudinal one on the volar and ulnar aspect of the forearm from the proximal third of the forearm to its distal insertion on the pisiform (TECH FIG 1A).

  • Dissection is carried out through the subcutaneous layer and the forearm fascia, onto the muscle belly proximally and onto the tendon insertion distally.

    • The ulnar nerve and artery lie radial to the tendon and are carefully identified and protected, including the dorsal ulnar sensory branch in the distal aspect of the wound.

• The tendon is transected at its distal insertion on the pisiform, and a grasping suture is placed (TECH FIG 1B).

• The FCU is then freed of its fascial insertion back to the most proximal aspect of the wound to allow full mobilization of the muscle to its dorsal position (TECH FIG 1C).

• Full mobilization of the muscle to the proximal third of the forearm has been shown to increase its vector as a forearm supinator, in addition to its wrist extension moment arm.7

   

   

   

   

   

   

   

  A B C

   

  TECH FIG 1 • A. A longitudinal incision is made down the ulnar aspect of the forearm from the proximal third of the forearm to the pisiform, with a small distal curve to allow visualization of the ulnar nerve and artery, which are just radial to the flexor carpi ulnaris at the level of the pisiform. B. The flexor carpi ulnaris tendon is transected distally at its insertion on the pisiform, with a grasping suture placed through the distal end of the tendon. C. The tendon is fully mobilized back to the proximal third of the muscle belly to allow the muscle to be transferred to the dorsal wrist with a straight line of pull.

   

  TRANSFER OF THE FLEXOR CARPI ULNARIS TO THE EXTENSOR CARPI RADIALIS BREVIS TENDON

  • A second incision is made over the dorsal radial aspect of the wrist diagonally over the second dorsal compartment (ECRB, ECRL) of the wrist (TECH FIG 2).

• Just distal to where the first dorsal compartment tendons (abductor pollicis longus and extensor pollicis brevis) cross the second dorsal compartment, a generous

   

   

  TECHNIQUES

   

  fascial window over the second dorsal compartment is made to fully expose the ECRB and ECRL tendons.

  • A subcutaneous tunnel is then made in direct line from the proximal end of the ulnar incision to the radial incision to allow a straight line of pull for the tendon transfer.

     

     

     

• The FCU tendon is then woven into the ECRB tendon using the Pulvertaft weave technique and tensioned so that the wrist sits at rest against gravity in a neutral position.

• Standard wound closure is performed after the tourniquet is deflated.

   

  TECH FIG 2 • A second incision made dorsally allows dissection of the extensor carpi radialis brevis as a recipient tendon. The flexor carpi ulnaris tendon is passed through a subcutaneous tunnel and woven into the extensor carpi radialis brevis tendon.

   

  PEARLS AND PITFALLS

  Tensioning of the tendon transfer ■ If the tendon transfer is tensioned too tightly, the wrist will sit in extension at rest and

  too much wrist extension will occur with active range of motion. A careful assessment of tendon transfer tensioning is necessary to avoid this pitfall.

  • However, if the tendon transfer is tensioned too loosely, the wrist will not achieve as much wrist extension as desired. If one is to err, one would prefer too little tension than too much, as the transfer tends to tighten over time, particularly if performed in a young child with significant remaining growth potential.

   

   

  POSTOPERATIVE CARE

• The postoperative rehabilitation regimen is imperative to maximize surgical results.

• The limb is immobilized in a cast for 1 month after tendon transfer surgery.

• After 1 month, the cast is removed and a custom splint is used holding the wrist in a neutral position (as well as protecting any other procedures that were done concomitantly).

• The splint is worn full time for an additional month but is removed three to five times a day for active range of motion and light functional activities.

• After 1 month of full-time splinting, the patient then progresses to nighttime splinting only with active functional use of the hand during the day, including lifting and strengthening exercises.

• Individualized sessions with a therapist experienced in tendon transfer rehabilitation are very helpful to maximize use of the limb and incorporate the wrist into activities of daily living, but success may be limited by the overall extent of the patient’s cerebral palsy involvement.

   

  OUTCOMES

• The greatest functional benefit in upper extremity surgery has been reported with correction of the wrist flexion deformity, regardless of the transfer used.

• Beach et al,2 as an example of the correction achieved, reported a postoperative arc of motion of almost 50 degrees,

  centered around the neutral axis, at greater than 5 years of follow-up.

  • Significant aesthetic improvement was noted as well in 90% of patients.

  • A functional outcome study of 134 cerebral palsy patients treated surgically showed that the average functional improvement was from use of the hand as a poor passive assist to use of the hand as a poor active assist.6 This article advocates performing multiple procedures simultaneously for correction of the elbow, forearm, wrist, and thumb in a single surgical setting.

     

    COMPLICATIONS

• All surgical procedures carry risk, and this must be weighed against the potential benefits that most commonly are achieved.

• Preoperatively, patients must be screened for anesthetic complications as follows:

  • A bleeding screen for patients on long-term Depakote an-tiseizure medications

  • Screening for bladder and lung infections, particularly for patients with poor urinary or pulmonary control

  • Nutritional status (height and weight percentiles for age)

• Intraoperative attention to wound care is imperative to avoid wound healing problems.

• Wounds may need a postoperative drain to prevent hematoma formation.

   

  • Nerve and artery injury can be avoided with appropriate planes of dissection and a thorough knowledge of the pertinent anatomy.

  • Postoperatively, the splint or cast should be adequate to allow for postoperative swelling and should be split if excessive swelling is encountered.

    • Many children with spasticity do not have normal preoperative sensory or motor findings and may not have normal mentation, so normal parameters cannot be used to monitor for compartment syndrome.

    • Premature removal of the cast or splint, as well as overzealous patient activities, can lead to tendon rupture or attenuation.

    • Excessive immobilization can lead to excessive adhesion formation, diminishing the eventual functional use.

  • Long-term problems most commonly involve loss of the muscle balance achieved at the time of the surgery.

    • Many children have tendon transfers as young as 7 years old; with continued skeletal growth, they may have recurrent deformity.

    • Overcorrection can also occur, with the “opposite” deformity occurring. “Fine-tuning” surgery may be necessary to address complications that develop after correction of the original deformity.

  • Several principles will help prevent these complications.

    • Do not overcorrect deformity, particularly in the younger child.

    • Leave options to reverse the surgical correction if necessary.

  • Keep functional grasp and release as the highest priority in surgical planning.

  • Avoid wrist arthrodesis, as this precludes the tenodesis effect of the wrist for finger use.

REFERENCES

1. Autti-Ramo I, Larsen A, Peltonen J, et al. Botulinum toxin injection as an adjunct when planning hand surgery in children with spastic hemiplegia. Neuropediatrics 2000;31:4–8.

2. Beach WR, Strecker WB, Coe J, et al. The use of the Green transfer in treatment of patients with spastic cerebral palsy: 17-year experience. J Pediat Orthop 1991;11:731–736.

3. Brand PW, Hollister A. Chapter 10: Operations to restore muscle balance to the hand. In: Brand PW, Hollister A, eds. Clinical Mechanics of the Hand, 2nd ed. Mosby, 1993:179–222.

4. Carlson MG. Cerebral Palsy. In: Green DP, Hotchkiss RN, Pederson WC, et al, eds. Green’s Operative Hand Surgery, 5th Ed. Philadelphia: Elsevier, Churchill Livingstone, 2005:1197–1234.

5. Van Heest A. Functional assessment aided by motion laboratory studies. Hand Clin 2003;19:565–571.

6. Van Heest AE, House J, Cariello C. Upper extremity surgical treatment of cerebral palsy. J Hand Surg Am 1999;24A:323–330.

7. Van Heest A, Murthy N, Sathy M, et al. The supination effect of tendon transfer of the flexor carpi ulnaris to the extensor carpi radialis brevis or longus: a cadaveric study. J Hand Surg Am 1999;24A: 1091–1096.

8. Van Heest AE. Applications of botulinum toxin in orthopaedics and upper extremity surgery. Tech Hand Up Extrem Surg 1997;1:27–34.

9. Wall SA, Chait LA, Ternlett JA, et al. Botulinum A chemodenerva-tion: a new modality in cerebral palsied hands. Br J Plast Surg 1993; 46:703–706.