This study reviewed arthroscopy, MRI and arthrography of the glenohumeral joint in children with obstetrical brachial plexus birth palsies. Eighty-four children ranging in age from 17 months to 13 ½ years underwent arthrography during surgery for internal rotation contractures of the shoulder. Thirty-six of children also underwent preoperative MRI’s and 37 children were evaluated arthroscopically. The results of arthrography revealed substantial deformity in 61% of the children. Thirty-three had a concentric glenoid, 8 a flat glenoid, 17 a biconcave glenoid and 26 a pseudoglenoid. The severity of the pre-operative contracture correlated with the severity of the deformity. The mean external rotation contracture was 2 degrees for concentric glenoids, -9 degrees for those with a flat glenoid, -13 degrees for those with a biconcave glenoid and –24 degrees with a pseudoglenoid. There was a strong correlation between arthrographic and MRI findings in the 36 patients who underwent both evaluations. The humeral head on MRI became more asymmetric with increasing glenoid deformity and elongation in the coronal plan with the anterior aspect of the head articulating with the posterior aspect of the glenoid. The findings at arthroscopy were more limited. However, they did reveal irregularities and cavitations of the anterior aspect of the glenoid. With increasing age and deformity, hypertrophy and contracture of the anterior capsule and rotator interval were frequently encountered. The authors felt the subscapularis and rotator interval were the primary sites of contracture. With increased deformity of the glenoid, the humeral head moved from posterior to anterior as the arm was positioned from internal to external rotation. This finding was most pronounced in older children with substantial deformity. In addition, there was notable pliability of the cartilage, especially in younger children. The pressure of the humeral head on the glenoid resulted in deformation that resolved with traction on the arm.
This article provides further clarification of the glenohumeral joint deformities noted in patients with obstetrical brachial plexus palsies and internal rotation contractures of the shoulder. Preoperative plain radiographs are often inconclusive with respect to the deformity of the glenohumeral joint. MRI is non-invasive and is able to distinguish between labrum, cartilage, glenoid version and humeral head deformity. However, it does require sedation or possibly general anesthesia. Arthrography may be done at the time of operative intervention and may minimize the need for additional anesthetic; however, it is unable to distinguish between specific structures and specific geometry. The authors allude to the potential for arthroscopic contracture release of the rotator interval and subscapularis but do not provide any results. Currently it appears that arthroscopy may be of limited value in evaluating glenohumeral deformity in patients with obstetrical brachial plexus palsy. However, it may be an adjunct to its treatment.
J Bone Joint Surgery