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SAN FRANCISCO -- After conducting a detailed analysis of the forces
at work during commonly performed maneuvers by elite basketball
players, Duke University Medical Center researchers believe they now
better understand the causes of season-ending and potentially
career-threatening stress fractures of the foot.

The solution,
they continued, may be as simple as adding additional arch support to
athletic shoes. This preventative action appears to relieve the
constant stresses and pressures suffered by the fifth metatarsal, a
bone on the outside of the mid-foot between the ankle bone and the
small toe.

The results of the Duke study were presented March 13,
2004, at the annual meeting of the American Academy of Orthopedic
Surgery by orthopedic surgeon Joseph Guettler, M.D., of William
Beaumont Hospital, Royal Oak, Mich. Guettler conducted the research
while a sports medicine fellow at Duke in the Michael W. Krzyzewski
Human Performance Laboratory (K Lab) at Duke.

"These stress
fractures of the fifth metatarsal are a prevalent and potentially
devastating injuries suffered by elite basketball players, and they
appear to occur as a result of the repetitive stresses placed on the
bone," Guettler said. "The fractures are tiny, but over time they can
coalesce into one large fracture. It is the equivalent in the foot of
what happens in shin splints."

Since there have been few studies
of stress fractures of the fifth metatarsal under "real-world"
conditions, the Duke researchers wanted to characterize the stresses
acting upon the bone, when they were most likely to occur, and if
anything could be done to lessen the pressures.

For their
analysis, the researchers recruited 11 male college basketball players.
Electronic pressure sensors capable of continuous readings were
inserted into the soles of their shoes. The researchers also placed
electromyography (EMG) sensors on two of the muscles of the foot to
measure the electrical activity of the muscles.

The players were
then asked to perform three of the most common maneuvers experienced
during a typical basketball game: landing on one foot following a jump
during a simulated lay-up, changing direction 180 degrees during a
side-to-side shuffle, and pivoting 180 degrees during a forward sprint.

Detailed
measurements of maximum forces, work and time elapsed were taken while
players wore their normal shoes and also in shoes with accentuated arch
support.

"The greatest elapsed time and greatest average work
beneath the fifth metatarsal occurred during pivot moves," Guettler
explained. "And the greatest forces were experienced when players
landed after lay-ups. The forces under the fifth metatarsal were
consistently greater then the maneuvers were performed in shoes without
an enhanced medial arch.

"The added arch caused a statistically
significant reduction in the maximum forces encountered under the fifth
metatarsal during the pivot and lay-up maneuvers," he said.
"Additionally, peak EMG measurements were higher for all the maneuvers
for players with the arch. It appears that supporting the arch may
reduce the stresses encountered beneath the fifth metatarsal and help
prevent these injuries in the future."

The researchers said that
muscles within the foot and how they respond also play an important
role in determining whether or not a specific action has a negative
effect on the fifth metatarsal. The finding that EMG activity was
elevated when arch support was used is an interesting one, Guettler
said, adding that this phenomenon is a future avenue of research.

"This
study is a perfect example of the type of work conducted in the K Lab,"
said Claude T. Moorman, M.D., director of sports medicine at Duke and
senior member of the research team. "We identify a problem, conduct
research to better understand the issues, and then come up with
solutions -- all with the goal of preventing injury and improving
performance."

Moorman said that the Duke findings run counter to
what had been assumed by shoe manufacturers -- namely that high arch
support was the cause of fifth metatarsal stress fractures. No one,
however, had conducted the research to determine the answer, Moorman
said.

Moorman and his K Lab colleagues are taking this research one step further.

"We
plan to use magnetic resonance imaging (MRI) techniques to image
basketball players over time to hopefully gain a better understanding
of the sequence of events leading up to the injury, Moorman continued.
"The MRI is ideal for capturing the tiny fractures that are the
hallmark of the condition."

Both Guettler and Moorman said that
while the current study looked at elite athletes, the findings are also
applicable to all types of athletes who participate in sports requiring
similar maneuvers.

The study was supported by the K Lab and the Piedmont Society, a group founded by orthopedic surgeons who trained at Duke.

Other members of the Duke were Gregory Riskan, Jeffrey Bytomski, D.O., Christopher Brown, M.D. and Jan Richardson, Ph.D.