Musculoskeletal MR goes deep to catch football injuries

Knee and ankle injuries vex contact sport athletes. American football players, in particular, put up with torn menisci and a condition known as high ankle sprain that usually gets misdiagnosed. Two studies presented at the 2005 RSNA meeting provide insight on the diagnosis and management of these injuries.

In the first, researchers reviewed 101 MR exams from 330 candidates for the 2005 professional football draft. They confirmed 57 lateral and 26 medial meniscal tears. Existing clinical data primarily track medial meniscal tears, which affect the inner knee joint. The investigators, headed by Dr. Jeffrey Towers, an associate professor of radiology at the University of Pittsburgh Medical Center, speculated that the unusually high percentage of lateral lesions correlated with anterior cruciate ligament tears. ACL tears are common among elite college football players, and 80% of meniscal tears that occur in association with ACL tears are in the outer knee joint. Getting tackled generally means taking a hit outside of the knees, which can tear both the lateral meniscus and the ACL.

The study, however, found that three-quarters of the lateral meniscal tears were isolated injuries. And the highest incidence occurred in linemen and defensive secondary players-tacklers, not tacklees. The discovery may have a significant impact on improving physicians' ability to diagnose and treat the condition, Towers said.

"The fact that we found a concentration of lateral meniscal tears could mean that there's something about this sport that predisposes athletes to this injury," he said. "Now that we recognize this, there may be ways to address players the most at risk."

The second paper by the same team used x-rays to identify indirect signs of high ankle sprain, or syndesmotic tear, a condition that affects the ligament holding the tibia and fibula together. Painful physical exam is the current diagnostic standard.

Researchers evaluated 18 candidates for the 2005 professional football draft who had a history of high ankle sprain. Sixteen had received x-rays, while two underwent MRI. Fourteen x-rays showed periostosis, or abnormal bone growth, at the lower part of the tibia. Both MR scans revealed edema at the same site. Injuries were distributed relatively evenly among various position players.

"This periostosis provides physicians with an indirect sign of high ankle sprain that is decisive in diagnosing this injury," Towers said.