1. A 45 year old woman was travelling in a car when she met with an accident. She discovered she was not able to stand up on her own due to severe pain in her left hip. She described the details of the crash to the emergency personnel who came to the conclusion that it was a ‘dashboard injury’ of the left lower limb. She complains of pain and inability to move her left lower limb. On examination, there is absence of the femoral pulse on the left side. The most probable diagnosis at this point would be,

1. Osteoporosis
2. Slipped capital femoral epiphysis
3. Posterior dislocation of the hip
4. Anterior dislocation of the hip
5. Avascular necrosis

Choice C is correct – Posterior dislocation of the hip often occurs due to posteriorly directed force on an internally rotated, adducted and flexed hip, which commonly occurs as a ‘dashboard injury’ during motor vehicle accidents. Classing the femoral pulse is absent on the ipsilateral side – ‘Narath’s sign’.

 Choice A is incorrect – Osteoporosis refers to generalised bone disorder characterised by decreased bone density. It occurs commonly in postmenopausal women due to estrogen deficiency and can predispose to fractures. But no such history or finding is present in the case above

Choice B is incorrect – Slipped Capital Femoral Epiphysis (SCFE) occurs commonly in obese, adolescent males wherein the femoral head is displaced posteriorly and medially causing thigh/ knee pain and a painful limp.

 Choice D is incorrect – Anterior displacement does not occur with dashboard injuries and does not show absence of femoral pulses ipsilaterally.

 Choice E is incorrect – Avascular necrosis often presents with slow insidious onset as a painless limp