The medial rotation contracture caused by weak external rotation secondary to obstetric brachial plexus injury leads to deformation of the bones of the shoulder. Scapular hypoplasia, elevation and rotation deformity are accompanied by progressive dislocation of the humeral head. Between February and August 2005, 44 children underwent a new surgical procedure called the ‘triangle tilt’ operation to correct this bony shoulder deformity. Surgical levelling of the distal acromioclavicular triangle combined with tightening of the posterior glenohumeral capsule (capsulorrhaphy) improved shoulder function and corrected the glenohumeral axis in these patients. The posture of the arm at rest was improved and active external rotation increased by a mean of 53° (0° to 115°) in the 40 children who were followed up for more than one year.

There was a mean improvement of 4.9 points (1.7 to 8.3) of the Mallet shoulder function score after surgical correction of the bony deformity.

Residual muscle weakness in obstetric brachial plexus palsy results in soft-tissue contractures which limit the functional range of movement and lead to progressive glenoid dysplasia and joint instability. We describe the results of surgical treatment in 98 patients (mean age 2.5 years, 0.5 to 9.0) for the correction of active abduction of the shoulder. The patients underwent transfer of the latissimus dorsi and teres major muscles, release of contractures of subscapularis pectoralis major and minor, and axillary nerve decompression and neurolysis (the modified Quad procedure). The transferred muscles were sutured to the teres minor muscle, not to a point of bony insertion. The mean pre-operative active abduction was 45° (20° to 90°). At a mean follow-up of 4.8 years (2.0 to 8.7), the mean active abduction was 162° (100° to 180°) while 77 (78.6%) of the patients had active abduction of 160° or more. No decline in abduction was noted among the 29 patients (29.6%) followed up for six years or more. This procedure involving release of the contracted internal rotators of the shoulder combined with decompression and neurolysis of the axillary nerve greatly improves active abduction in young patients with muscle imbalance secondary to obstetric brachial plexus palsy.