Shoulder internal rotation contracture in brachial plexus birth injury: proximal or distal subscapularis release?

BACKGROUND

In cases of brachial plexus birth injury with internal rotation contracture of the shoulder, the subscapularis muscle may be released proximally, from the subscapular fossa, or distally, along with periarticular soft tissues arthroscopic to the glenohumeral joint. We hypothesized that the indication for each procedure would rely primarily on patients' bone remodeling potential and periarticular soft-tissue contractures, performing proximal releases in patients aged < 4 years and periarticular distal releases in older patients. The purpose of this study was to analyze the outcomes such a strategy could provide.

METHODS

All patients presenting with brachial plexus birth injury-related shoulder internal rotation contractures who underwent a subscapularis release were included; in addition, to restore the joint axial balance, the infraspinatus was systematically reanimated with a tendon transfer (ie, latissimus dorsi or lower trapezius) during the same operating time. Chart review yielded preoperative and postoperative clinical and radiographic measurements, including active and passive range of motion of the shoulder in external rotation (ER) with the arm at the side of the body, the modified Mallet score, glenoid version, and the percentage of the humeral head arthroscopic to the middle of the glenoid process.

RESULTS

Between July 2012 and January 2018, 28 children were operated on at our institution. In patients who underwent proximal subscapularis release (n = 13), significant improvements were observed regarding active shoulder ER, passive shoulder ER, the modified Mallet score, glenoid version, and the percentage of the humeral head arthroscopic to the middle of the glenoid process, averaging 58° ± 32° (P < .0001), 56° ± 20° (P < .0001), 9.7 ± 3.1 points (P = .0006), 15° ± 10° (P = .0034), and 24% ± 20% (P = .0113), respectively, after a mean follow-up period of 4 years. Following distal release procedures (n = 15), these improvements averaged 26° ± 29° (P = .0024), 27° ± 28° (P = .0011), 3.3 ± 4.1 points (P = .0049), 2° ± 17° (P = .4086), and 4% ± 18% (P = .215), respectively, after a mean follow-up period of 3 years.

CONCLUSION

When combined with axial rebalancing of the joint, the proximal release of the subscapularis muscle appears to be sufficient to provide satisfactory functional outcomes in patients with great bone remodeling potential and supple periarticular soft tissues. In older patients, a more comprehensive release of the glenohumeral joint's arthroscopic aspect seems to provide lower but still significant clinical improvements.

Proximal subscapularis release for the treatment of adduction-internal rotation shoulder contracture in obstetric brachial plexus palsy

INTRODUCTION

The purpose of this paper was to evaluate the results on shoulder function following isolated proximal subscapularis release in children with Erb's palsy.

METHODS

A retrospective study was conducted on 64 consecutive children with Erb's palsy who underwent a Carlioz proximal subscapularis release between 2001 and 2012. Fifty children with complete records and a minimum follow-up of 2 years were included for evaluation. Age at surgery ranged from 1.3 to 4.5 years (average 2.6 years). Preoperative active shoulder abduction/anterior elevation, active external and internal rotations as well as the Mallet score were compared with those found at 6 and 24 months postoperatively using the Student paired t test, with a confidence interval of 95 %. The results were compared between children <3 years of age at surgery and those older, and between children who had an isolated C5-C6 and those with greater involvement. p < 0.05 was considered statistically significant.

RESULTS

Active abduction improved 21° at 6 months and 31° (total) at 2 years (p < 0.01) with an overall Mallet abduction score improvement of 0.58 at 6 months and 0.6 (overall) at 2 years (p < 0.01). Active external rotation improved 52° at 6 months and 35° (total) at 2 years (p < 0.01) with an overall Mallet external rotation score improvement of 1.3 at 6 months (p < 0.01) and 0.52 (overall) at 2 years (p = 0.013). There was no statistically significant change in internal rotation (p = 0.37). We found no correlation between the child's age or the severity of involvement at surgery and the end result.

CONCLUSION

Proximal subscapularis release according to Carlioz is simple and effective in improving overall shoulder function in children with obstetric brachial plexus palsy, mainly abduction and external rotation. Improvement tends to reach a plateau around 6-12 months postoperatively.