Natural reverse shoulder joint following a conservatively treated proximal humeral fracture in adolescence-a 46-year follow-up case report.

We report a case of a naturally-developed reverse shoulder joint following a proximal humeral fracture sustained at the age of 16 years and managed non-operatively. Over time, progressive post-traumatic remodelling resulted in an inversion of the native glenohumeral anatomy, resembling the biomechanical configuration of a reverse shoulder arthroplasty as originally described by Grammont. The humeral head remodelled into a concave socket-like structure, while the glenoid progressively assumed a convex articulation. At 46 years of follow-up, the patient demonstrated an unusual pattern of glenohumeral osteoarthritis but remained pain-free, with a functional shoulder (Constant score 69). To our knowledge, this is the first reported case of a post-traumatic native reverse shoulder joint resulting from an adolescent proximal humeral fracture with long-term follow-up.