Increased Risk of Femoral Neck Stress Fractures in Patients With Cam or Pincer Morphology

Previous studies suggest a relationship between femoroacetabular impingement (FAI) and femoral neck stress fractures (FNSF), due to pathologic biomechanics in the setting of femoral head abutment (cam morphology) and/or acetabular overcoverage (pincer morphology). The purpose of this study is to evaluate the association between cam or pincer morphology and FNSF, compared to a control group of patients without hip pain. A retrospective review of the electronic medical record at a single institution was queried for patients with FNSF over a 10-year time period from January 2011-2021. These patients were compared to a control group with diagnostic radiographs and a chief complaint that was not hip pain presenting to the institution's emergency department. Hip morphology was evaluated radiographically. A multivariate logistic regression was used to investigate an association between FNSF and cam or pincer morphology. Eighty-three patients with FNSF and a mean age of 38.6 years were compared to 55 healthy controls with a mean age of 35.8 years. Patients in the FNSF group were more often female, white, and had lower BMI. These patients were also more likely to have associated cam morphology (p = 0.010). Binary logistic regression demonstrated a statistically significant independent association between both cam (OR 5.2, p = 0.01) and pincer (OR 4.6, p = 0.022) morphology with FNSF when controlling for demographic variables. Black race and higher BMI were protective factors for FNSF (OR 0.09, OR 0.84, p < 0.01). In summary, radiographic cam morphology, superolateral acetabular overcoverage, female sex, and lower BMI are risk factors for sustaining FNSF, while the black race was found to be protective.