Abstract
BackgroundShoulder abnormalities are the major cause of morbidity in upper brachial plexus birth palsy (BPBP). We developed a rat model of upper trunk BPBP and compared our findings to previously reported animal models and to clinical findings in humans.MethodsForty-three 5-day-old newborn rats underwent selective upper trunk neurectomy of the right brachial plexus and were studied 3 to 20 weeks after surgery. The passive shoulder external rotation was measured and the shoulder joint was assessed bilaterally by a 7.2T MRI bilaterally.ResultsWe found a marked decrease in passive shoulder external rotation, associated with a severe subscapularis muscle atrophy and contracture. None however developed the typical pattern of glenohumeral dysplasia.ConclusionsIn contradiction with previous reports, our study shows that the rat model is not adequate for preclinical studies of shoulder dysplasia. However, it might serve as a useful model for studies analyzing shoulder contracture occurring after upper BPBP.
Highlights
Shoulder abnormalities are the most common long-term complication and the major cause of morbidity in upper trunk brachial plexus birth palsy (BPBP) [1]
Shoulder functional impairment is due to a progressive development of muscle abnormalities, with shoulder internal rotation contracture leading to major joint deformities [2,3,4]
There was a statistically significant decrease of passive external rotation in the involved shoulder compared to uninvolved shoulder (23.85°±27.5 vs 79.62°±3.8 respectively) (P
Summary
Shoulder abnormalities are the most common long-term complication and the major cause of morbidity in upper trunk brachial plexus birth palsy (BPBP) [1]. An animal model of shoulder disorders after BPBP would permit the assessment of these deformities, help define the muscle changes and would provide a base for treatment research. The purpose of this study is to use a similar rat model, combined with MRI evaluation, to better delineate muscle and joint shoulder changes after BPBP. Shoulder abnormalities are the major cause of morbidity in upper brachial plexus birth palsy (BPBP). We developed a rat model of upper trunk BPBP and compared our findings to previously reported animal models and to clinical findings in humans
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