OPERATIVE MANAGEMENT OF THE UPPER EXTREMITY IN CEREBRAL PALSY
The operative management of the upper extremity in a child with cerebral palsy (CP) represents one of the most complex challenges in pediatric orthopedic surgery. Because the primary pathology is a non-progressive upper motor neuron lesion resulting in a progressive musculoskeletal deformity, surgical intervention must be meticulously planned. The surgeon must balance the biomechanical correction of spasticity and contracture against the patient's baseline neurologic deficits, cognitive capacity, and voluntary motor control.
GOALS OF SURGICAL INTERVENTION
The overarching goals of operative treatment in a child with cerebral palsy must be highly specific, individualized, and realistic. The primary functional objectives are aimed at providing useful grasp and release mechanisms and ensuring acceptable hygiene.
Clinical Pearl: Normal hand function is an unrealistic goal in cerebral palsy. The surgeon must explicitly manage the expectations of both the patient and the parents preoperatively. Fine manipulation is rarely, if ever, improved by surgery due to the underlying cortical deficit.
Secondary goals may include improving the cosmetic appearance of the hand by correcting an unsightly contracture. While cosmesis is considered a modest goal, it can have profound psychosocial benefits for the developing child.
Functional grasp and release are only possible in children who possess sufficient sensibility to allow an awareness of the extremity. Without adequate proprioception and tactile feedback, the child will experience "developmental apraxia," effectively ignoring the limb regardless of its mechanical alignment. Interestingly, stereognosis—the ability to perceive the form of solid objects by touch—has been shown to improve postoperatively. This is likely secondary to gains in motor function and the increased functional use of the upper extremity, which enhances cortical mapping and sensory feedback loops.
Surgical Warning: Undercorrection rather than overcorrection of a deformity or dysfunction is always preferred. Over-lengthening a spastic flexor can completely obliterate the patient's grip strength, leaving them with a biomechanically aligned but entirely functionless hand.
PRINCIPLES OF PATIENT SELECTION
The success of upper extremity surgery in cerebral palsy is dictated almost entirely by patient selection. The clinical evaluation must rigorously assess the patient's motor control, sensibility, cognitive status, and movement disorder subtype.
The Ideal Surgical Candidate
The ideal candidate for functional upper extremity surgery is characterized by the following traits:
* Diagnosis: Spastic hemiplegia.
* Cognition: Cooperative, intelligent, and highly motivated to participate in postoperative rehabilitation.
* Baseline Function: Possesses a pattern of grasp and release that is already functional to some extent, indicating intact cortical motor pathways.
* Sensibility: The hand should be reasonably sensitive (intact two-point discrimination and proprioception).
The Poor Surgical Candidate
Conversely, surgery for functional improvement is contraindicated in patients with the following profile:
* Cognition: Severe mental retardation, precluding compliance with postoperative therapy.
* Movement Disorder: Definite athetosis or dystonia in the extremity. Tendon transfers in athetoid patients are highly unpredictable and often fail due to fluctuating muscle tone.
* Sensibility: An insensate hand that the child visually and functionally ignores.
* Contractures: Severe, fixed joint contractures where the wrist cannot passively be brought to neutral, and the fingers cannot be extended even when the wrist is maximally flexed.
Considerations by CP Subtype
- Spastic Diplegia: Children with spastic diplegia rarely exhibit sufficient upper extremity spasticity to warrant surgical intervention. Their primary deficits are typically confined to the lower extremities.
- Spastic Quadriplegia (Total Body Involvement): These patients generally possess too little voluntary motor control to benefit from surgery aimed at improving grasp and release. However, they are excellent candidates for palliative surgery aimed at improving hygiene, easing dressing, and preventing skin maceration in the palm (e.g., severe thumb-in-palm or wrist flexion deformities).
TIMING OF SURGICAL INTERVENTION
The timing of surgical intervention is critical and follows a developmental and biomechanical hierarchy. As a general rule, indicated surgery is usually carried out between 4 to 8 years of age. Intervening during this window is ideal because the child is old enough to cooperate with postoperative therapy, yet young enough that surgery can be performed before significant, irreversible joint capsular contractures develop.
- Early Interventions (Ages 4-6): Soft tissue operations to correct dynamic flexion deformities of the wrist and pronation deformities of the forearm are indicated earliest. Myotomies and fractional lengthenings are highly effective at this age to rebalance forces before skeletal changes occur.
- Intermediate Interventions (Ages 6-10): Tendon transfers are typically performed later, once the child's motor patterns have fully matured and they can reliably participate in the neuromuscular re-education required for a transfer.
- Late Interventions (Adolescence): Arthrodeses (joint fusions) are reserved as salvage procedures for older children and adolescents with fixed deformities that cannot be managed with soft tissue releases alone.
SURGICAL OPTIONS AND BIOMECHANICS
The orthopedic surgeon has an armamentarium of procedures to address the spastic upper extremity, each with specific biomechanical consequences.
Muscle-Tendon Lengthening (Myotomy and Tenotomy)
Tendon lengthening weakens the target muscle, diminishes its excursion, and reduces the stretch reflex. This subsequent reduction in spasticity allows antagonistic muscles to influence joint function to a greater extent.
* Advantage: Requires minimal postoperative cognitive compliance and can be performed safely in both spastic and athetoid patients.
* Technique: Fractional lengthening at the myotendinous junction is preferred over Z-lengthening of the tendon substance, as it preserves continuity and reduces the risk of catastrophic over-lengthening.
Tendon Transfers
Tendon transfers redirect a deforming spastic muscle to augment a weak antagonist.
* Prerequisites: Transfers require significant postoperative compliance for cortical retraining. The transferred muscle should ideally be synergistic (e.g., transferring a wrist flexor to a wrist extensor).
* Contraindications: Tendon transfers cannot overcome a fixed joint deformity; the joint must be passively supple. Furthermore, they are notoriously unreliable in athetoid patients due to unpredictable phase firing.
Arthrodesis
Arthrodesis is highly effective for stabilizing joints but comes at the cost of mobility.
* Thumb Metacarpophalangeal (MCP) Joint: Arthrodesis is exceptionally useful in stabilizing the thumb MCP joint during the reconstruction of a severe thumb-in-palm deformity, providing a rigid post against which the fingers can pinch.
* Wrist Arthrodesis: Used to correct fixed flexion deformities.
Pitfall: Fusing the wrist sacrifices the "tenodesis effect" (the windlass effect). Many CP patients rely on active wrist flexion to passively extend their fingers for release, and active wrist extension to passively flex their fingers for grasp. Fusing the wrist in neutral may permanently strip the patient of their ability to release objects if their active finger extensors are weak.
MANAGEMENT OF THE PRONATION CONTRACTURE
Pronation contracture of the forearm is one of the most common and debilitating deformities in the spastic hemiplegic upper extremity. Severe pronation prevents the child from performing basic activities of daily living, such as accepting objects in the palm or grasping a cup of water (which requires the forearm to be in neutral or slight supination).
Gschwind and Tonkin Classification
Gschwind and Tonkin classified pronation deformities into four distinct groups to guide surgical decision-making:
* Group I: Active supination beyond neutral is present. (Usually managed conservatively or with minimal soft tissue release).
* Group II: Active supination is possible only to neutral.
* Group III: No active supination is possible, but passive supination is preserved.
* Group IV: Fixed pronation contracture; passive supination is impossible.
Pronator Teres Rerouting (Sakellarides Technique)
Sakellarides et al. devised a highly effective operation principally to correct dynamic pronation contractures. The rationale is that transferring the pronator teres (PT) tendon produces better correction than a simple release because it simultaneously eliminates a deforming force while actively providing a new force for supination.
Surgical Steps:
1. Approach: A longitudinal incision is made over the middle third of the volar-radial forearm.
2. Identification: The interval between the brachioradialis and the flexor carpi radialis is developed. The superficial radial nerve is identified and protected. The insertion of the pronator teres on the lateral aspect of the radius is exposed.
3. Harvest: The tendon is detached from its insertion along with a robust strip of periosteum to maximize length and provide strong tissue for reattachment.
4. Rerouting: The tendon is mobilized proximally. It is then passed dorsally around the radius (from volar to dorsal, then radial) through the interosseous space, effectively converting its line of pull from a pronator to a supinator.
5. Fixation: The tendon is inserted into the bone using a drill hole or suture anchors while the forearm is held in maximum supination.
Outcomes: In the original series of 22 patients treated with this method, 82% gained an average of 46 degrees of active supination. Bunata reported similar improvements in 31 patients, noting an average active supination improvement of 65 degrees, with the average dynamic resting position improving from 26 degrees of pronation to 7 degrees of pronation. The primary indication for this surgery is a dynamic pronation posturing of 25 degrees or greater.
Brachioradialis Rerouting and Pronator Quadratus Release
For more severe or complex contractures, alternative techniques have been developed. Ozkan et al. described a brachioradialis rerouting procedure combined with the release of both the pronator teres and the pronator quadratus.
In this technique, the brachioradialis is detached distally, passed interosseously or around the radius, and reattached to act as a supinator. In their series, this combination yielded an average gain of 81 degrees of supination with no instances of overcorrection. Release of the pronator quadratus is particularly critical in Group III and Group IV deformities where distal radioulnar joint contracture contributes significantly to the pathology.
POSTOPERATIVE PROTOCOLS AND PROGNOSIS
Postoperative management is as critical as the surgical execution. Following tendon transfers or rerouting procedures (such as the Sakellarides PT rerouting), the upper extremity is typically immobilized in a long-arm cast with the elbow at 90 degrees of flexion and the forearm in full supination for 4 to 6 weeks.
Following cast removal, a rigorous occupational therapy regimen is initiated. Therapy focuses on neuromuscular re-education, utilizing biofeedback and repetitive task training to integrate the transferred muscle into its new phase of activity. Night splinting is often continued for 6 to 12 months to prevent the recurrence of contractures during the vulnerable period of scar remodeling and growth spurts.
Prognostic Indicators
The ultimate success of operative management in the cerebral palsy upper extremity hinges on the patient's preoperative neurologic baseline. Extensive studies have consistently demonstrated that patients with poor voluntary motor control experience significantly less functional improvement after surgery compared to those with fair-to-good voluntary control.
Clinical Pearl: Voluntary motor control remains the single most reliable predictor of functional outcome after surgical intervention in the spastic upper extremity. Surgery modifies the peripheral biomechanics, but the central nervous system dictates the functional ceiling.
By adhering to strict patient selection criteria, respecting the biomechanical principles of the spastic limb, and executing precise, well-timed surgical interventions, the orthopedic surgeon can profoundly improve the quality of life, hygiene, and functional independence of the child with cerebral palsy.
