Prevalence of shoulder subluxation diagnosed via ultrasound screening in infants with birth brachial plexus injuries
Gabrielle Goodlin, Sarah Lewis, Sarah Menashe, Ramesh Iyer, Raymond Tse, Marisa OsorioAbstract
Introduction
Posterior shoulder subluxation and glenohumeral dysplasia are known secondary complications of birth brachial plexus palsies (BBPP) that contribute to functional limitations. The prevalence of shoulder subluxation in infants with BBPP and the timeline of when subluxation occurs in the first year of life remain unclear, with prior literature ranging from 7% to 56% prevalence, in part owing to lack of standardized protocols for screening.
Objective
To determine the prevalence of posterior shoulder subluxation in infants with BBPP and persistent neurological deficits with universal ultrasound screening.
Design
Retrospective cohort study setting: Tertiary multidisciplinary specialty clinic.
Patients
114 infants with BBPP referred to a multidisciplinary brachial plexus clinic between 2011 and 2023 with persistent neurological deficits beyond neurapraxic injuries.
Interventions
Screening shoulder ultrasound examinations were performed at 3 and 6 months of age (unless they otherwise met the institutional cutoff of alpha angle ≥40 degrees for early intervention).
Main Outcome Measure(s)
Alpha angle, Active Movement Score (AMS) for shoulder movements, shoulder passive range of motion (PROM).
Results
On initial screening at 3 months, 83.3% (95 patients) had shoulder subluxation. Sixty‐six patients (57.9%) had alpha angles ≥40 degrees (severe). The mean alpha angle for the affected shoulder was 45.57 (SD 17.12), and 26.92 (SD 5.84) for the contralateral unaffected shoulder. On linear regression, decreased PROM with shoulder external rotation in adduction was correlated with higher alpha angle measurements ( β = −0.599, 95% CI −0.758 to −0.308, r = −0.484, p < .001). Of the patients with normal PROM‐ER, 74.6% (50 patients) had shoulder subluxation on imaging. 43.9% (29 patients) with severe subluxation had normal PROM‐ER. Thirty‐seven patients underwent a second screening ultrasound at 6 months of age, of which 64.9% (24 patients) had subluxation, and 21.6% (8 patients) had severe subluxation. Only 4 patients without subluxation at 3 months developed mild subluxation at 6 months.
Conclusions
The prevalence of shoulder subluxation is much higher than previously reported in the literature. Over half of patients with subluxation on imaging have no PROM deficits on exam. Multicenter prospective longitudinal data are needed to further evaluate if early detection of shoulder subluxation allows for timely intervention and treatment for joint preservation.