Review Question - QID 214803

Magnetic resonance imaging (MRI) reveals a compression-sided femoral neck stress fracture, with a fatigue line spanning greater than 50% of the diameter of the femoral neck. Given the length of the fracture, this is an injury that is best treated surgically with percutaneous screw fixation.

Stress fractures of the femoral neck can occur in younger, active patients or elderly, osteoporotic patients, and may be located on the compression or tension side of the femoral neck (Illustration A). In compression-sided fractures, the fracture begins at the infero-medial aspect of the femoral neck and extends superiorly, perpendicular to the axis of the neck. Tension-sided fractures begin at the supero-lateral aspect of the neck and propagate inferiorly, perpendicular to the axis of the femoral neck. Nondisplaced stress fractures of the femoral neck located on the compression side spanning less than 50% of the femoral neck may be treated nonoperatively with protected weight-bearing and close observation for 6–8 weeks. Compression-sided fractures spanning more than 50% of the femoral neck require internal fixation. Nondisplaced fractures on the tension side of the femoral neck are at an increased risk for fracture displacement and require internal fixation.

Florschutz et al. performed a review of femoral neck fractures. They report that stress fractures of the femoral neck should warrant a thorough endocrine workup to detect and treat any underlying metabolic bone pathologies. Younger patients should be educated on appropriate training activities. They also note that providers must be on the lookout for the female athlete triad, and should investigate any history of amenorrhea, eating disorder and/or overuse/insufficiency fracture.

Boden et al. reviewed high-risk stress fractures. They report that these fractures develop as the hip musculature becomes fatigued with prolonged activity and subsequently loses its protective shock absorptive effects. Intrinsic factors, such as coxa vara and osteopenia, may also predispose the femoral neck to injury. They conclude that MRI should be obtained in all patients in which a stress fracture of the femoral neck is suspected.

Armstrong et al. reviewed stress fractures in young, active-duty patients during summer training at the United States Naval Academy. They performed a case-control study of 31 patients with stress fractures and 31 patients without. They note that significant, acute weight loss (which is typically associated with entry-level military training) is an independent risk factor for the development of stress fracture. Interestingly enough, they did not encounter any patients with the female athlete triad.

Figure A is a T2-weighted coronal MRI demonstrating a compression-sided femoral neck fracture. Figure B is a T1-weighted coronal MRI demonstrating the same. Illustration A demonstrates the tension and compression side of the femoral neck.

Incorrect Answers:

Answer 1: Though complete femoral neck stress fractures or compression-sided femoral neck fractures involving > 50% of the neck should be treated with surgical fixation, this is not a complete femoral neck fracture.
Answer 3: Compression-sided femoral neck fractures are initially treated non-operatively if it involves < 50% of the femoral neck. Given the information in the question stem, however, the patient in the vignette has a fracture that spans >50% of the femoral neck.
Answer 4: This is a compression-sided femoral neck fracture, not a tension-sided fracture.
Answer 5: Tension-sided femoral neck fractures should be treated with operative fixation given their high risk of displacement.