Lumbar Spinous Process Impaction Injuries Caused by Extension Stress in Adolescent Athletes: A Report of Two Cases.

Lumbar spinous process injuries in adolescent athletes are rare and primarily attributed to traction mechanisms during flexion stress. Here, we present two cases of spinous process contusion and fracture, believed to result from impaction of adjacent spinous processes during lumbar extension. Case 1 involved a 14-year-old male volleyball player who presented with localized tenderness between the L4 and L5 spinous processes and extension-induced lower back pain. Magnetic resonance imaging (MRI) revealed high signal intensity at the caudal aspect of the L4 spinous process on short-tau inversion recovery (STIR) sequences; however, computed tomography (CT) revealed no evidence of fracture. Symptoms fully resolved after three months of lumbar orthosis use combined with cessation of sports activities, as confirmed by follow-up clinical and imaging assessments. Case 2 involved an 11-year-old male basketball player who experienced acute lower back pain immediately after a hyperextension injury sustained during lifting in a hyperextended posture. MRI demonstrated high signal intensity at the cranial L4 spinous process on STIR sequences, and CT revealed a fracture line. Continued play with extension restriction using a lumbar orthosis resulted in bony union within three months. These cases highlight a novel mechanism involving impaction during lumbar extension for lumbar spinous process injury in adolescent athletes. Early recognition and conservative management focusing on extension restriction are key to achieving favorable outcomes.