BackgroundGlenohumeral posterior external rotation contractures and scapular winging are frequently overlooked problems in residual neonatal brachial plexus injury (NBPI). Recent attention has emphasized their impact on vital functions such as feeding and hygiene. This study aims to present the epidemiology of posterior glenohumeral (GH) contractures in a significant pediatric NBPI population and explore contributing factors. MethodsWe conducted a retrospective analysis of data collected from January 2019 to November 2022, involving a case series of 262 children with residual NBPI. The data included demographics, palsy level, prior surgical history, and the modified Mallet scale. Glenohumeral passive internal rotation in abduction (IRABD) and cross-body adduction (CBADD) angles were measured bilaterally. Subjects were categorized into 'Belly-' (Mallet Hand-to-Belly <3) and 'Belly+' (Mallet Hand-to-Belly ≥3) groups. ResultsMedian participant age was 7.9 years (range: 3.5 – 21 years). Extension injury patterns included Erb's palsy (56.5%), extended Erb's palsy (28.6%), and global palsy (14.9%). Contractures exceeding 10, 20, and 30 degrees were prevalent in both IRABD and CBADD angles. The 'Belly-' group (9.5%) demonstrated a significant reduction in both angles compared to the 'Belly+' group. Weak correlations were found between IRABD (r=0.390, p<0.0001) or CBADD (r=0.163, p=0.0083) angles and Mallet hand-to-abdomen item. Glenohumeral reduction and Hoffer procedures led to a notable decrease in CBADD angle, without affecting 'Belly-' prevalence. Global injuries exhibited decreased angles compared to Erb's group. ConclusionsExternal rotation glenohumeral contractures are prevalent in residual NBPI, impacting midline access. Surprisingly, history of glenohumeral procedures or extensive injuries did not increase the likelihood of losing the ability to reach the belly. ROC analysis suggests specific thresholds for maintaining this ability.
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