Impaired growth of denervated muscle contributes to contracture formation following neonatal brachial plexus injury

Anterior release of elbow flexion contractures in children with obstetrical brachial plexus lesions

PURPOSE

A flexion contracture of the elbow is common in upper obstetric brachial plexus palsy. One less than 30° involves no major aesthetic or functional abnormalities, whereas for one greater than 30°, conservative treatment with serial splints produces variable results. We evaluated anterior release of the elbow with partial tenotomy of the anterior brachialis muscle and of the biceps, for their effect on elbow flexion contractures.

METHODS

We performed 10 anterior releases of the elbow with lengthening of the distal tendons of the biceps and the anterior brachialis muscle. All patients had upper obstetric brachial plexus palsies (C5-C6) and elbow flexion contractures of 35° or greater (range, 35° to 60°). The flexion strength of the elbow was 4 or higher on the British Medical Research Council scale, and the patients had no bone abnormalities in the elbow region.

RESULTS

After a mean follow-up period of 3 years, the mean gain in extension was 28° (range, 20° to 35°). All patients maintained flexion strength. Elbow extension was 2° less than obtained at surgery and was maintained during follow-up. All patients were satisfied or very satisfied, and none presented major complications, except hypertrophic scarring to a greater or lesser extent at the incision site.

CONCLUSIONS

Anterior release of the elbow is a useful method for treating elbow flexion contractures of more than 35° and can reduce the deformity to bring it within functional range without compromising flexion.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Could muscle deformity in children with spastic cerebral palsy be related to an impairment of muscle growth and altered adaptation?

Skeletal muscle deformity is common in children with spastic cerebral palsy (CP), but the underlying mechanisms are unclear. This review explores some possible factors which may influence the development of muscle deformity in CP. Normal muscle function and growth appear to depend on the interaction of neuronal, endocrinal, nutritional, and mechanical factors, and also on the development of an appropriate balance between muscle protein synthesis and degradation, and between the development of contractile and non-contractile components. In this context, the changes seen in muscle in children with CP are reviewed and discussed. It is suggested that the development of muscle deformity in children with CP may be related to a multifactorial impairment of muscle growth, on which adaptation of the extracellular matrix due to altered loading may be imposed.

Biceps brachii long head overactivity associated with elbow flexion contracture in brachial plexus birth palsy

BACKGROUND

The etiology of elbow flexion contracture in children with brachial plexus birth palsy remains unclear. We hypothesized that the long head of the biceps brachii muscle assists with shoulder stabilization in children with brachial plexus birth palsy and that overactivity of the long head during elbow and shoulder activity is associated with an elbow flexion contracture.

METHODS

Twenty-one patients with brachial plexus birth palsy-associated elbow flexion contracture underwent testing with surface electromyography. Twelve patients underwent repeat testing with fine-wire electromyography. Surface electrodes were placed on the muscle belly, and fine-wire electrodes were inserted bilaterally into the long and short heads of the biceps brachii. Patients were asked to perform four upper extremity tasks: elbow flexion-extension, hand to head, high reach, and overhead ball throw. The mean duration of muscle activity in the affected limb was compared with that in the contralateral, unaffected limb, which was used as a control. Three-dimensional motion analysis, surface dynamometry, and validated function measures were used to evaluate upper extremity kinematics, elbow flexor-extensor muscle imbalance, and function.

RESULTS

The mean activity duration of the long head of the biceps brachii muscle was significantly higher in the affected limb as compared with the contralateral, unaffected limb during hand-to-head tasks (p = 0.02) and high-reach tasks (p = 0.03). No significant differences in mean activity duration were observed for the short head of the biceps brachii muscle between the affected and unaffected limbs. Isometric strength of elbow flexion was not significantly higher than that of elbow extension in the affected limb (p = 0.11).

CONCLUSIONS

Overactivity of the long head of the biceps brachii muscle is associated with and may contribute to the development of elbow flexion contracture in children with brachial plexus birth palsy. Elbow flexion contracture may not be associated with an elbow flexor-extensor muscle imbalance, as previously hypothesized. The negative impact of elbow flexion contracture on upper extremity function warrants future research in the development of preventive and therapeutic techniques to address elbow flexion contractures in children with brachial plexus birth palsy.