An 86-year-old patient involved in a motor vehicle collision struck a knee on the dashboard.

The correct answers are B. Femur fracture and E. Posterior hip dislocation.

This mechanism is classically known as a “dashboard injury”, where the knee strikes the dashboard during a motor vehicle collision. The force is transmitted along the femur toward the hip.

Why B is correct (Femur fracture):

The force applied to the knee travels up the femur, which can result in:

Femoral shaft fractures

Significant internal bleeding

NREMT trauma guidance states:

“High-energy impacts to the lower extremities can result in femur fractures.”

Why E is correct (Posterior hip dislocation):

Dashboard injuries commonly cause:

Posterior displacement of the femoral head from the acetabulum

This occurs when the femur is driven backward while the hip is flexed

NREMT-aligned content:

“A blow to the knee in a seated position can result in posterior hip dislocation.”

Why the other options are incorrect:

A. Tibia fracture: More commonly associated with direct lower leg trauma, not classic dashboard mechanism.

C. Ruptured peritoneum: Not a typical injury from this mechanism.

D. Rupture of the bladder: More associated with pelvic fractures, not isolated dashboard knee impact.

Exact Extracts:

“A dashboard injury can transmit force up the femur causing hip dislocation.”

“Posterior hip dislocation is commonly associated with knee impact in MVCs.”

“Femur fractures are common in high-energy trauma.”