Understanding acute apophyseal spinous process avulsion injuries.

Apophyseal spinous process avulsion injury was first described in 1941. Since then, there have been sparse additional reports in the literature. The authors report their second case, involving an elite adolescent tennis player. The patient underwent surgical excision of the avulsed spinous process 12 weeks after initial presentation and experienced complete resolution of back pain. The authors provide the first reported histopathological analysis of the avulsion fracture site in the literature for both of their cases. The avulsion injury of the interspinous ligament was characterized by hypercellular fibrocartilage tissue, similar to that seen in severe Osgood-Schlatter's disease. The key physical examination finding in patients with avulsion spinous process fractures is acute tenderness directly over the fracture site that worsens with flexion rather than extension (unlike in spondylolysis). Patients should have routine radiographs, including dynamic flexion-extension views, magnetic resonance imaging, and computed tomography. The authors conclude that after 6 months of nonsurgical management for an athlete, surgical excision should be offered as an alternative. In both of their cases, nonsurgical management failed. Surgical excision offers definitive and simple treatment, as well as early return to athletic activities. Both patients were allowed to return to their competitive level of performance 6 weeks after surgery.