MRI provides best option for imaging groin injuries

MR findings show that conjoint tendinitis and osteitis pubis, two commonly diagnosed causes of groin pain in soccer and rugby players, are far less common than believed, according to two papers presented at the 2004 RSNA meeting. The studies are significant because the two conditions usually require surgery. The conjoint tendinitis diagnosis, called Gilmore's groin, is often overdiagnosed.

Prof. Francis W. Smith, a radiologist at the Positional MRI Centre at Woodend Hospital, University of Aberdeen, U.K., analyzed groin pain in 127 male athletes aged 11 to 30. About 90% were soccer players, and all had a history of groin pain for more than three weeks. In half of the cases (63), MR images revealed no abnormality. There were 19 cases of osteitis pubis, nine stress fractures (eight inferior pubic ramus), five adductor muscle tears, 10 cases of inflammation of the hip rotator muscle, six cases of hamstring muscle tear, and four cases of iliopsoas tendinitis. The remaining 11 cases had various other findings, but none showed evidence of conjoint tendinitis, even though 25 of the athletes went on to surgery.

Smith has seen a number of cases in which the groin pain continues months after surgery.

Smith concluded that careful MR examination is advisable for athletes suffering from groin pain. Offset coronal T2-weighted and STIR sequences, which are especially good at visualizing stress fractures and adductor muscle tears, add important information in imaging the pelvis for groin pain, he said.

A study conducted at the University of Dublin used MR to image 70 athletes with groin pain. The researchers looked for isolated adductor dysfunction, isolated osteitis pubis, and combinations of the two.

Adductor dysfunction, identified by an accessory cleft sign, was found in 54 of the 70 cases, said lead researcher Dr. Patricia Cunningham. In each case, the side of the cleft sign corresponded with the side of the groin pain. Osteitis pubis was found in just 12 patients. Four patients had normal scans, while 20 showed signs of both pathologies. The images were obtained on a 1.5T scanner using a body coil with coronal and axial T1-weighted and STIR tissue excitation.

The Dublin team concluded that adductor dysfunction appears to precede the development of osteitis pubis, and isolated osteitis pubis as a cause of groin pain is uncommon.