Femoral Neck Stress Fractures

Stress fractures are common overuse injuries in the lower extremities that occur with either abnormal stress on normal bone (fatigue fracture) or normal stress on abnormal bone (insufficiency fracture). Location of a stress fracture and associated potential for delayed union, nonunion, and refracture facilitate designation of a fracture as either "high risk" or "low risk." Femoral neck stress fractures account for less than 5% of all stress fractures. Based on the biomechanics of the proximal femur, these fractures may be on the inferomedial compression side or the superolateral tension side. Tension-side fractures are of "high risk" and compression-side fractures are of "low risk." Once a diagnosis of stress fracture is made, a thorough evaluation for modifiable endocrinologic and nutritional risk factors is undertaken and a treatment and prevention program commenced. Nonsurgical treatment with crutch-assisted non-weight bearing ambulation is indicated for incomplete compression-side fractures. Surgical treatment is indicated for (1) complete fracture with or without displacement, (2) tension-sided incomplete fractures, and (3) compression-sided incomplete fractures that have failed nonsurgical treatment for a minimum of 6 weeks. Percutaneous screw fixation with 6.5- or 7.3-mm screws is the standard of care for surgical treatment. Stress fracture displacement requires urgent anatomical reduction. Thus, if a closed reduction is unable to be achieved under anesthesia, then an anterior Smith-Petersen approach is necessary to anatomically reduce and fix the fracture. Postoperatively, following percutaneous screw fixation of a nondisplaced stress fracture, patients may begin weight bearing as tolerated. Complications include displacement, nonunion, delayed union, varus malunion, and avascular necrosis.