Redefining the Incidence of Infantile Glenohumeral Dysplasia following Brachial Plexus Birth Injury.

Background: Glenohumeral dysplasia (GHD) is a well-documented sequela following brachial plexus birth injury (BPBI). Despite its morbidity, the precise incidence of infantile GHD varies widely in the literature.

Methods: This prospective cohort study included consecutive patients diagnosed with a nontransient BPBI between November of 2021 and November of 2023. Patients were enrolled into the study from a specialized, high-volume brachial plexus clinic. A diagnosis of GHD was made by an alpha angle measurement on ultrasonography greater than 30 degrees in the setting of abnormal shoulder function, as indicated by Active Movement Scale scores for shoulder abduction, shoulder flexion, and external rotation.

Results: Forty-two infants with a diagnosis of nontransient BPBI were initially seen at a mean age of 1.6 months. During continuous follow-up, 50% of patients ( n = 21) were diagnosed with GHD with a mean alpha angle of 35 ± 8 degrees and at a mean age of 3.2 ± 1.4 months. At the time of diagnosis, infants had a median Active Movement Scale score of 4 (interquartile [IQR], 3 to 5) for shoulder abduction, 5 (IQR, 3 to 5) for shoulder flexion, and 4 (IQR, 2 to 5) for external rotation. The presence of upper extremity fracture was significant when comparing BPBI patients with GHD and those without, although the relative risk was not significant.

Conclusions: This study demonstrates a high incidence of GHD in a prospective evaluation of infants with BPBI using serial ultrasonography. Those caring for patients with BPBI should be aware of such a common sequela and initiate early screening and management protocols to prevent and treat the deformity.

Clinical question/level of evidence: Risk, III.