Impact of tendon transfer on scapulothoracic and glenohumeral motion in children with brachial plexus birth injuries.

Background: Tendon transfers are often utilized to improve shoulder external rotation and abduction in children with brachial plexus birth injuries and are designed to improve glenohumeral (GH) joint motion. However, changes in scapulothoracic (ST) and GH joint function after tendon transfer are not well defined. The purpose of this study was to quantify changes in GH, ST, and humerothoracic (HT) joint function before and after tendon transfer, and we hypothesized that tendon transfers would reorient the arc of motion into more external rotation and abduction, but not increase GH motion.

Methods: Motion analysis was performed in 15 children (ages 3-16) before and after transfer of teres major and/or latissimus dorsi. ST, GH, and HT joint angles were measured in a neutral, resting position and each of the modified Mallet positions. Joint angular displacements from the neutral position and the total arc of internal-external rotation for each joint were also calculated. Relevant joint angles, joint angular displacements, and internal-external rotation arcs were compared using multivariate analyses of variance with repeated measures and univariate posthoc analyses.

Results: Glenohumeral and HT external rotation were significantly increased in all positions postoperatively. The arc of GH internal-external rotation was unchanged, but oriented in more external rotation after surgery. Only 6 patients gained active external rotation. Glenohumeral and HT internal rotation were significantly decreased after surgery, but ST internal rotation was significantly increased. Two patients had loss of midline function. In the abduction position, GH elevation joint angles were unchanged, but ST and HT elevation increased.

Discussion: Only 4 patients gained active GH external rotation and maintained their internal rotation. Each of those patients underwent isolated tendon transfer without concomitant joint release. Seven patients maintained their preoperative internal rotation, which was attributed to increased ST internal rotation. The other half of patients lost internal rotation and gained external rotation through reorientation of the arc of rotation. Nine patients gained HT elevation, with 3 attributed to increased ST upward rotation, 5 attributed to a combination of increased ST upward rotation, and increased GH elevation, and 1 attributed to increased GH abduction contracture. These findings challenge the dogma that teres major/latissimus dorsi tendon transfers augment GH motion and highlight the importance of ST function for outcome determination.