During a teaching round on fracture classification, a resident is asked to identify the most common site of fracture in the femur when considering all age groups and injury mechanisms across the population.

Explanation

## Femoral Fracture Sites: Epidemiology and Classification **Key Point:** Intertrochanteric fractures are the most common type of femoral fracture across the entire population, accounting for approximately 50% of all proximal femur fractures. ### Epidemiological Distribution | Femoral Fracture Site | Percentage of All Femur Fractures | Age Group Most Affected | Mechanism | | --- | --- | --- | --- | | Intertrochanteric | 45–50% | Elderly (>65 years) | Low-energy fall | | Femoral neck | 35–40% | Elderly, young adults | Fall, high-energy trauma | | Subtrochanteric | 10–15% | Young adults | High-energy trauma | | Distal femoral | 5–10% | All ages | High-energy trauma, motor vehicle accidents | **High-Yield:** The intertrochanteric region is extracapsular, meaning the fracture line lies outside the hip joint capsule. This preserves the blood supply to the femoral head, reducing the risk of avascular necrosis (AVN) compared to intracapsular femoral neck fractures. ### Why Intertrochanteric Fractures Are Most Common 1. **Demographic Shift:** The global aging population has dramatically increased the incidence of low-energy falls in elderly patients 2. **Bone Quality:** Osteoporosis preferentially weakens the intertrochanteric region in elderly individuals 3. **Mechanism:** Simple falls from standing height are sufficient to cause fracture at this site in osteoporotic bone 4. **Anatomical Vulnerability:** The intertrochanteric region is a metaphyseal zone with mixed trabecular and cortical bone, making it mechanically weaker **Clinical Pearl:** Intertrochanteric fractures typically present with external rotation and shortening of the affected limb, and they bleed more profusely than femoral neck fractures due to the rich vascular supply in the extracapsular region. **Mnemonic: INTER-COMMON** — **INTER**trochanteric fractures are the **COMMON**est femoral fracture because they occur in the elderly with osteoporosis from simple falls.