Purpose: To prospectively evaluate the use and optimal timing of ultrasonographic (US) screening for posterior shoulder subluxation in infantswith brachial plexus birth injury (BPBI).
Materials and methods: Approval of the ethics committee and informed consent of guardians was obtained. This population-based prospective study included neonates with BPBI who were born in Helsinki from January 1, 2003 through December 31, 2006, and in whom BPBI was verified with sequential clinical examinations. US was performed at 1, 3, 6, and 12 months. Size (width and height) of the humeral head and its ossification center and congruency of the shoulder (alpha angle) were measured. Frequency of BPBI and permanent changes were evaluated. This study also included patients who were referred from the tertiary catchment area. For statistical analysis, 95% confidence intervals were calculated, and analysis of variance was performed.
Results: BPBI was seen in 132 of 41980 neonates (3.1 per 1000). In 27 cases (0.64 per 1000), BPBI did not heal during the 1st year of life and was considered permanent. The humeral head and its ossification center were smaller on the affected side in permanent BPBI. Nine patients with permanent palsy had posterior subluxation of the humeral head depicted with US (alpha angle, >30 degrees ). In five patients, posterior subluxation [corrected] was detected at 3 months. Nineteen of 21 patients with BPBI from the tertiary catchment area had permanent palsy. Ten of 19 patients developed posterior subluxation of the shoulder, which was verified with US. Altogether, three of these cases were not detected by surgeons. Posterior subluxation of the humeral head developed during the 1st year of life in one-third of patients with permanent BPBI. In more than one-half (55% [five of nine]) of the patients, posterior subluxation [corrected] was detected with US at 3 months, and in 89% (eight of nine), it was detected at 6 months.
Conclusion: US is a fast and useful tool for diagnosis of posterior subluxation of the humeral head, and examination of the glenohumeral joint should be performed at 3 and 6 months of age in infants with BPBI if symptoms persist.