Purpose: to alert readers to the possibility of a ruptured abdominal aortic aneurysm presenting with femoral neuropathy and back pain.

Method: Our patient presented with a short history of left leg weakness, numbness and back pain but was otherwise in a stable condition. An MR of his lumbar spine was initially performed on a 1T GE scanner and this was followed by an abdominal ultrasound scan and a spiral CT on a Siemen’s Somatom with reconstructions.

Results: The MR unexpectedly demonstrated a large abdominal aortic aneurysm and swelling of the left psoas muscle. These features were observed easily as the saturation band was placed anterior to the retroperitoneum.

Ultrasound confirmed these findings and the subsequent CT demonstrated precisely the point of rupture with contrast entering the left psoas muscle.

Conclusion: Rupture of an abdominal aortic aneurysm may present to the orthopaedic team with back pain and femoral neuropathy. This demands a high index of suspicion as timely intervention saves lives.