Early effects of muscle atrophy on shoulder joint development in infants with unilateral birth brachial plexus injury

V. M. van Gelein Vitringa, R.T. Jaspers, M.G. Mullender, W.J.R. van Ouwerkerk, J.A. van der Sluijs

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Aim Shoulder deformities in children with a birth brachial plexus injury (BBPI) are caused by muscle imbalances; however, the underlying mechanisms are unclear. The aim of this study was to assess the early interactions between shoulder muscles and shoulder joint development.Method In a retrospective magnetic resonance imaging (MRI) study of 36 infants (21 males, 15 females) younger than 12 months (mean 4.8mo) with unilateral BBPI, volumes and thicknesses of standardized segments of the infraspinatus, subscapularis, and deltoid muscles were measured in both shoulders and expressed as ratios of pathological/unaffected side. The relation between muscle ratios and humeral head subluxation, passive external rotation, glenoid version, and deformity was analysed.Results Compared with the unaffected side, the muscles of the affected side were of significantly smaller volume and thickness. The subscapularis was the most severely affected muscle, its volume being only 64% (SD 21%) and its thickness only 79% (SD 23%) of the corresponding values on the unaffected side (p<0.001). Severe subluxation was predicted by the combination of low infraspinatus and subscapularis volume ratios (r
Original languageEnglish
Pages (from-to)173-178
JournalDevelopmental Medicine and Child Neurology
Issue number2
Publication statusPublished - 2011

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