Residual brachial plexus birth palsy often affects the shoulder girdle. Upper trunk return is paramount for shoulder motion. Numerous muscles that provide internal rotation are spared from injury or reinnervate over time. In contrast, the infraspinatous muscle and external rotation frequently do not recover completely, which leads to an imbalance about the shoulder. This inequity predisposes the shoulder to an internal rotation contracture and posterior subluxation. The purpose of this study was to determine the congruity of the shoulder in children with brachial plexus birth palsies using ultrasound and compare these results to surgical findings.
Twenty-two children with residual brachial plexus birth palsies (mean age 4.8 years) underwent axial plane ultrasound using a posterior portal. The normal shoulder was scanned as a control. The shoulders were positioned in internal rotation during the examination. The results were classified as “congruent,” when the humeral head was in line with the posterior scapula, or “incongruent,” when the humerus was posterior to the line of the scapula. No attempt was made to differentiate subluxation from dislocation. The operative findings were classified slightly different. A “congruent” shoulder was defined as one in which the humeral head was articulating with the true glenoid. An “ incongruent” shoulder was one that either articulated with a false glenoid or one that was dislocated. Ultrasound reported 17 shoulders as incongruent and five as congruent. Surgical findings recorded 20 as incongruent and two as congruent. All shoulders diagnosed as incongruent on ultrasound were found incongruent at surgery. Diagnostic accuracy was 82%.
This report adds additional information regarding the use of ultrasound for the evaluation of the shoulder after brachial plexus birth palsy. Previous on-line scholarly reviews (Van der Sluijs et al. Deformities of the Shoulder in Infants Younger Than 12 Months With an Obstetric Lesion of the Brachial Plexus, J Bone and Joint Surg: 83B:551-555, 2001) highlighted the high prevalence and early onset of glenohumeral dysplasia after birth palsy. Van der Sluijs et al. used MR imaging as compared to ultrasound. The principal advantage of ultrasound over MR is the lack of anesthesia and ability to perform a dynamic examination. Although the authors mention this possibility, only static images were used. Examination throughout the available range would add additional information as to the reducibility of the glenohumeral joint and may increase the diagnostic accuracy.
Journal of Bone and Joint Surgery