MRI scores with basketball players at risk for injury

Research from Duke University, where stress fractures of the fifth metatarsal have been the proverbial Achilles heel of more than one Blue Devil basketball star, may help team practitioners identify players at risk for this injury even before symptoms develop.

In a study of 26 male college basketball players who underwent MR imaging before the 2003 season, signal abnormalities consistent with bone marrow edema in the metatarsal area led in two cases to interventions that relieved symptoms and did not progress to stress fracture. The findings were presented at the RSNA meeting Thursday.

In one case, an asymptomatic player with fifth metatarsal edema developed symptoms two weeks later, which were treated successfully with bone stimulation and a custom foot orthosis emphasizing medial arch support. Earlier research from the same institution, presented in March at the of the American Academy of Orthopaedic Surgeons meeting, demonstrated that this type of orthotic intervention reduced pressure under the fifth metatarsal during basketball drills.

In the second case, practitioners determined that abnormal signal in the third metatarsal area and the player's reports of midfoot pain were related to that player's unauthorized use of rigid orthoses in his shoes. Removal of the orthoses relieved the player's pain, said Dr. Nancy Major, an associate professor of radiology and surgery at Duke, who presented the study results.

A third player with abnormal signal in the second metatarsal developed a stress fracture before practitioners were able to intervene, Major said. Three other players exhibited mild signal abnormalities that were not suggestive of pathology.

Metatarsal stress fractures, though uncommon, occur more frequently in basketball players than in other athletes. Last year, the injury affected as many as five collegiate starters nationwide, and the Blue Devils average about one every other year, Major said.

Although no studies to date have attempted to prove that edema seen on MRI in asymptomatic individuals is actually predictive of stress fracture, Major said that in her experience the radiographic findings are more predictive of clinical symptoms in the feet than in other joints such as the knee.

"I think it has to do with stresses unique to feet in this particular sport," she said. "In these guys who are jumping and landing, we have to pay much more attention to that alteration because it's not going to get better. They don't rest; there's no down time."

Were college basketball teams to consider using MRI to screen players for edematous predictors of stress fractures, using an extremity scanner might seem a more cost-effective option than the 1.5 T magnet used in the Duke study. But Major cautioned that extremity scanners might not have the resolution necessary to identify clinically significant changes.

"I wouldn't want to do this kind of imaging on less than a 1T magnet," she said. "But as some of the extremity scanners are going to higher and higher field strengths, that may be an option in the future."