Oka K, et al. - Twenty patients with elbow flexion contracture and residual obstetric brachial plexus palsy (OBPP) were retrospectively studied for the 3D morphologic changes in the elbow joint. In addition, researchers tested if the shape of the distal humerus with flexion contracture in upper OBPP is hypoplastic in the trochlea, capitellum, and olecranon fossa. In line with the original hypothesis, the distal humerus with flexion contracture in upper OBPP was hypoplastic. Despite performing soft tissue contracture release, full extension of the elbow might be prevented by the shallow olecranon fossa. Evaluation of the morphology of the olecranon fossa is recommended to decide the treatment plan for elbow flexion contracture with OBPP.