Does preoperative abduction value affect functional outcome of combined muscle transfer and release procedures in obstetrical palsy patients with shoulder involvement?

BACKGROUND Obstetric palsy is the injury of the brachial plexus during delivery. Although many infants with plexopathy recover with minor or no residual functional deficits, some children don't regain sufficient limb function because of functional limitations, bony deformities and joint contractures. Shoulder is the most frequently affected joint with internal rotation contracture causing limitation of abduction, external rotation. The treatment comprises muscle release procedures such as posterior subscapularis sliding or anterior subscapularis tendon lengthening and muscle transfers to restore the missing external rotation and abduction function. METHODS We evaluated whether the preoperative abduction degree affects functional outcome. Between 1998 and 2002, 46 children were operated on to restore shoulder abduction and external rotation. The average age at surgery was 7.6 years and average follow up was 40.8 months. We compared the postoperative results of the patients who had preoperative abduction less than 90 degrees (Group I: n = 37) with the patients who had preoperative abduction greater than 90 degrees (Group II: n = 9), in terms of abduction and external rotation function with angle measurements and Mallet classification. We inquired whether patients in Group I needed another muscle transfer along with latissimus dorsi and teres major transfers. RESULTS In Group I the average abduction improved from 62.5 degrees to 131.4 degrees (a 68.9 degrees +/- 22.9 degrees gain) and the average external rotation improved from 21.4 degrees to 82.6 degrees (a 61.1 degrees +/- 23 degrees gain). In Group II the average abduction improved from 99.4 degrees to 140 degrees (a 40.5 degrees +/- 16 degrees gain) and the average external rotation improved from 33.2 degrees to 82.7 degrees (a 49.5 degrees +/- 23.9 degrees gain). Although there was a significant difference between Group I and II for preoperative abduction (p = 0.000) and abduction gain in degrees (p = 0.001), the difference between postoperative values of both groups was not significant (p = 0.268). There was also no significant difference between the two groups in the preoperative external rotation, the external rotation gain and the postoperative external rotation (p = 0.163, p = 0.181 and p = 0.803, respectively). CONCLUSIONS Obstetric palsy patients with shoulder sequela who had a preoperative abduction less than 90 degrees hadas good functional results using latissimus dorsi, teres major muscle transfer and subscapularis muscle release as the patients who hada preoperative abduction greater than 90 degrees.