This 44 year-old male presented with right hip pain and fever. The T2-weighted fat-saturated axial MR image above shows high signal in the pubic bones and pubic symphysis. The joint capsule bulges and is of high signal. High signal extends into the right obturator externus muscle. T1-weighted images suggested cortical bone destruction. After contrast administration there was enhancement of bone marrow and joint capsule.
The findings are consistent with septic arthritis of the pubic symphysis, with osteomyelitis of the adjacent pubic bones. Septic arthritis in adults is usually due to Staphylococcus aureus infection, however gonorrhoea, tuberculosis, brucellosis and Salmonella may also be the cause. Septic arthritis commonly occurs in acromioclavicular, sternoclavicular, and sacroiliac joints. It also commonly occurs in the spine (discitis) and symphysis pubis.
Reference: Dähnert W. Radiology Review Manual 5th edition. Lippincott, Williams & Wilkins 2003
Credit: Dr Laughlin Dawes