Causes / typical injury mechanism: Femoral neck fractures can be separated into osteoporotic femoral neck fractures of the elderly related to low-energy mechanisms and femoral neck fractures caused by high-energy trauma such as a motor vehicle accident or a fall from a height.

Femoral neck fractures are a common injury in the elderly population with an incidence of 142 per 100 000 US adults in 2013. In about 90% of cases, the mechanism of injury is a ground-level fall with an impact on the greater trochanter of the femur. The fall is generally low energy, and the fracture occurs secondary to poor bone health.

Femoral neck fractures in the younger population are less common and are mostly caused by high-energy trauma such as striking the knee against the dashboard in a motor vehicle accident or a fall from a height.

Femoral neck fractures in the elderly are a sign of poor bone health and have a high rate of morbidity and disability. Overall mortality following a femoral neck fracture has been reported as between 12% and 17% within the first year. Following treatment of femoral neck fractures, patients remain at risk for decreased independence requiring more assistance with activities of daily living as well as assistive walking devices. In general, patients who used a cane prior to a femoral neck fracture may require a walker following the injury, while patients who used a walker previously are at risk for requiring a wheelchair. Patients may require a higher level of care during and following recovery, threatening patients' independent activities of daily living.

Femoral neck fractures are often referred to as hip fractures as well as intertrochanteric or pertrochanteric hip fractures. While inter- or pertrochanteric fractures are also related to poor bone health in the elderly population, the fracture is extracapsular and treatment approaches differ. Femoral neck fractures are intracapsular, and the fracture is bathed in synovial fluid, not allowing for callus formation and leading to decreased fracture healing potential.

Classic history and presentation: The classic history is an elderly White woman who lives a sedentary lifestyle and presents after a ground-level fall. Often, these patients have dementia or other underlying health conditions that put them at a higher risk for falling.

Prevalence:

• Age – Most often seen in patients older than 60 years, with the average age reported as between 72 and 80 years.
• Sex / gender – Significant female predominance and also more common in White people.

Risk factors: There are many risk factors that make someone more likely to sustain a femoral neck fracture, most notably having osteoporosis and a high risk of falling. Some of the modifiable risk factors for femoral neck fracture include alcohol use, smoking, underweight body mass index (BMI), decreased level of sun exposure, and a low level of physical activity. Nonmodifiable risk factors include White ethnicity, female sex, older age, history of a prior femoral neck fracture, and family history of osteoporotic fractures.

Some medical conditions have been shown to be associated with femoral neck fractures including primary hyperparathyroidism, diabetes mellitus, celiac disease, chronic renal disease, depression, anorexia nervosa, chronic liver disease, hypothyroidism, hyperthyroidism, and positive HIV status. As well, many medications have been linked to femoral neck fractures due to their osteoporotic effects, classically steroids, or due to their central nervous system (CNS) effects, classically benzodiazepines, which increase the risk of falls.

Garden classification:

1. Incomplete nondisplaced fracture
2. Complete nondisplaced fracture
3. Incomplete displaced fracture
4. Complete displaced fracture

Pauwels classification:

1. Fracture at an angle of 30 degrees or less from the horizontal plane
2. Fracture between 30 and 50 degrees
3. Fracture greater than 50 degrees

Related topics: femoral neck stress fracture, hip fracture