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Structural changes in muscle and glenohumeral joint deformity in neonatal brachial plexus palsy
Simone Hogendoorn1, Karlijn L J van Overvest, Iain Watt
1Department of Orthopaedics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. s.hogendoorn@lumc.nl
Insights
Rotator cuff muscle degeneration in children with neonatal brachial plexus palsy can cause significant glenohumeral deformities. Early intervention to address muscular imbalances may improve joint congruency and surgical outcomes.
Area of Science:
- Pediatric Orthopedics
- Neurorehabilitation
- Musculoskeletal Imaging
Background:
- Internal rotation contracture is a common complication in children with neonatal brachial plexus palsy.
- Persistent contractures can lead to the development of osseous deformities in the pediatric glenohumeral joint.
Purpose of the Study:
- To investigate the correlation between osseous deformities of the glenohumeral joint and structural muscle changes in the rotator cuff due to denervation.
- To analyze the impact of different brachial plexus lesion types on glenohumeral joint deformities.
Main Methods:
- Magnetic resonance imaging (MRI) of both shoulders was performed on 102 children with residual neonatal brachial plexus palsy.
- Measurements included glenoid version, humeral head subluxation (posterior, medial, superior), and muscle status (normal, atrophic, fatty degeneration) of the rotator cuff and deltoid muscles.
Main Results:
- Muscle degeneration was most pronounced in the subscapularis.
- Glenoid version and posterior humeral subluxation correlated with rotator cuff muscle abnormalities.
- Glenohumeral deformities were more severe in C5-C6 (C7) lesions compared to complete brachial plexus lesions.
Conclusions:
- Structural rotator cuff muscle differences influence humeral head forces, contributing to glenoid fossa osseous deformities.
- Glenohumeral deformities are more severe in C5-C6 (C7) lesions, impacting internal rotation.
- Addressing muscular imbalances in C5-C6 (C7) lesions may reduce joint incongruency and enhance surgical results.
Background:
Internal rotation contracture of the shoulder is common in children with neonatal brachial plexus palsy. A long-standing contracture may cause osseous deformities in the developing shoulder. The purpose of the study was to evaluate the relationship between osseous deformities of the glenohumeral joint and structural differences due to muscle denervation in the rotator cuff muscles.
Methods:
One hundred and two children with residual neonatal brachial plexus palsy underwent magnetic resonance imaging of both shoulders. The glenoid version and posterior, medial, and superior subluxation of the humeral head were measured. The shapes of the glenoid and the humeral head were categorized, and the infraspinatus, supraspinatus, subscapularis, and deltoid muscles were scored as being normal, atrophic, or atrophic with fatty degeneration.
Results:
Muscle degeneration was most prominent in the subscapularis muscle. Glenoid version correlated with the structural differences in the subscapularis muscle. Posterior subluxation of the humeral head and the shape of the glenoid correlated with all abnormal rotator cuff muscles. Superior humeral subluxation correlated only with changes in the supraspinatus muscle. Medialization and the shape of the humeral head were not associated with atrophic changes of the rotator cuff. Regeneration of the rotator cuff muscles was not significantly different in patients with a C5-C6 (C7) or a complete brachial plexus lesion. However, the changes in glenoid version, the degree of posterior humeral subluxation, and the degree of medial humeral subluxation were significantly more severe in patients with a C5-C6 (C7) lesion compared with those in patients with a complete lesion of the brachial plexus.
Conclusions:
Structural differences in the rotator cuff muscles alter the direction of the humeral head forces on the developing glenoid fossa and can lead to osseous deformities. Glenohumeral deformities are significantly greater with a C5-C6 (C7) lesion than with a complete brachial plexus lesion in which the large internal rotators are also affected. Reducing the muscular imbalance that occurs with a C5-C6 (C7) lesion could diminish glenohumeral joint incongruency and may improve the outcome of subsequent soft-tissue release or tendon transfer surgery.
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