Case: A 58-year-old woman underwent successful reverse total shoulder arthroplasty for a proximal humerus fracture. Three years later, she sustained a periprosthetic humerus fracture after a fall and was treated conservatively. She healed with an abundance of callus and subsequently developed delayed-onset radial nerve palsy at 3 months, despite minimal change in humeral alignment and avoidance of the use of any compressive external braces or splints.
Conclusions: Minimally displaced periprosethetic humerus fractures can lead to delayed radial nerve palsy from callus entrapment, and there should be increased awareness of this potential complication when counseling and treating patients conservatively.