Case 9

A 40 year old male was admitted to our hospital after 72 hrs in April 2006 as a road traffic accident case. The bus on which he was traveling was hit by an overtaking truck. On examination he was conscious but was unable to move his left lower limb which was 4 cm shorter than the right and was rotated externally. Left gluteal region and hip was swollen without any open injury. His ipsilateral knee was also swollen and painful

What is your differential diagnosis and what would you do next?