A 36-year-old is admitted to the hospital following a motor vehicle accident. An X-ray of the pelvis was obtained and shown below. What major muscle group is primarily responsible for the affected femur’s elevated position?
1.Hip abductors
2.Hi lateral rotators
3.Hi extensors
4.Hi adductors
Explanation:
The above image shows the result of a “dashboard injury” of the right hip: posterior dislocation of the hip with the femur internally rotated and adducted. Conversely, if the dislocation were anterior, the femur would be externally rotated and abducted.
The hip abductors include the gluteus medius, gluteus minimus, gluteus maximus, and tensor fascia latae.
Hip abduction relies on the acetabulum’s function as a fulcrum; without the acetabulum, the abductors instead pull the femur proximally, altering the lines of action of many muscles. The end result is the adduction and internal rotation seen here, partially obscuring the lesser trochanter. For reference to the femur’s normal position in this patient, see the contralateral leg. Note that a posterior dislocation carries a 10-20% chance of injuring the sciatic nerve.