Late-onset radial nerve palsy associated with conservatively managed humeral fracture. A case report and suggested classification system.

Radial nerve palsy can occur with humerus fracture, either at the time of injury (primary) or during reduction (secondary). Late-onset radial nerve palsy (not immediately related to injury or reduction) has been very seldom reported in the English literature. We describe a case of late-onset radial nerve palsy, which developed 9 weeks after an attempted closed management of a midshaft humerus fracture. Exploration of the nerve was performed. The radial nerve was found to be stretched over the ends of the fracture. Open reduction and external fixation of the fracture with mobilization of the nerve from the fracture site lead to complete return of radial nerve function occurring by 3 months. We recommend exploration of cases of late-onset radial nerve palsy in contrast to primary or secondary radial nerve palsy, which can be treated conservatively. Our experience suggests that the cause of the palsy is a continuous ongoing pathology and not a single time event as in primary or secondary cases. Radial nerve palsies associated with humeral fracture should be classified as either primary (at the time of injury), secondary (at the time of reduction), or late onset (not related to either injury or reduction).