Age Influence Upon Glenohumeral Remodeling After Shoulder Axial Rebalancing Surgery in Brachial Plexus Birth Injury

Abstract

Background: Shoulder rebalancing procedures have been proven to provide satisfactory functional improvements in patients with shoulder external rotation (ER) deficit due to brachial plexus birth injury (BPBI). However, the influence of age at the time of surgery on osteoarticular remodeling remains uncertain. The purposes of this retrospective case series were (1) to assess the age impact on glenohumeral remodeling and (2) to determine an age limit after which significant changes can no longer be expected. Methods: We reviewed preoperative and postoperative magnetic resonance imaging data of 49 children with BPBI who underwent a tendon transfer to reanimate active shoulder ER, with (n=41) or without (n=8) concomitant anterior shoulder release to restore passive shoulder ER, at a mean age of 72 ± 40 months (19;172). Mean radiographic follow-up was 35 ± 20 months (12;95). Univariate linear regressions were used to assess the influence of age at the time of surgery upon changes of glenoid version, glenoid shape, percentage of the humeral head anterior to the glenoid midline, and glenohumeral deformity. Beta coefficients with 95% CI were calculated. Results: Improvements of glenoid version, glenoid shape, percentage of the humeral head anterior and glenohumeral deformity significantly decreased by 0.19 degrees [CI=(−0.31; −0.06), P=0.0046], 0.02 grade [CI=(−0.04; −0.01), P=0.002], 0.12% [CI=(−0.21; −0.04), P=0.0076], and 0.01 grade [CI=(−0.02; −0.01), P=0.0078] per additional month of age at the time of surgery, respectively. The threshold of 5 years was identified as the age at the time of surgery after which significant remodeling no longer occurred. No significant postoperative changes were observed in patients without glenohumeral dysplasia on preoperative magnetic resonance imaging. Conclusion: In the setting of BPBI-related glenohumeral dysplasia, the younger the surgical axial rebalancing of the shoulder, the greater the glenohumeral remodeling seems to be. Such procedure seems to be safe in patients without significant joint deformity on preoperative imaging. Level of Evidence: Therapeutic—Level IV.