Clinical Diagnosis of the Infantile Shoulder Subluxation in Residual Brachial Plexus Birth Injury and Its Correlation With Ultrasound Diagnosis

Abstract

Introduction and aims of study: Timely detection of shoulder subluxation in infants with brachial plexus birth injury (BPBI) is essential to prevent the progression of glenohumeral deformity. Shoulder ultrasonography (USG) is routinely used to detect an infantile subluxation/dislocation, but its use is limited because of the paucity of expert radiologists in developing countries. The aim of this study was to determine the clinical examination predictors to determine shoulder subluxation in patients with BPBI correlating with ultrasound confirmation. Methods: We prospectively studied children who presented to our hospital between 2017 and 2021 diagnosed as brachial plexus birth injury. In patients developing internal rotation contracture of the shoulder, we looked for 3 standard clinical signs: reduced passive external rotation <60 degrees, deep anterior crease (DAC) and relatively short arm segment. Shoulder subluxation was defined as USG measurement of alpha angle>30 degrees and ossific nuclei of the humerus lying behind the dorsal scapular line. Sensitivity and specificity were used to assess their efficacy in clinical diagnosis of shoulder subluxation in different groups. The predicted probability of shoulder subluxation from each prediction rule was compared with actual distributions based on USG confirmation. Results: Of the 58 BPBI infants who developed PER<60 degrees at the shoulder, 41 had USG confirmed shoulder subluxation. The 2 independent predictors of shoulder subluxation (PER<45 degrees and DAC) were identified in the current patient population based on data analysis. The presence of short arm segment is a very specific marker of shoulder subluxation but not sensitive. The predicted probability of shoulder subluxation from the prediction rule combining all the 3 markers were similar to the actual distributions in the current patient population. Conclusions: PER<45 degrees and presence of deep anterior crease are clinical markers indicating shoulder dislocation in patients with BPBI developing reduced external rotation at the shoulder. On the basis of the proposed clinical diagnosis algorithm, the above markers along with the selective use of USG can help in early detection and treatment of infantile shoulder dislocation.