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Insights into Rare but Devastating Football Hip Injury

Published July 2, 2003 | Updated January 20, 2016

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Duke Health News919-660-1306

DURHAM, N.C. – In the first such review of its kind, Duke University
Medical Center researchers have analyzed their experiences in treating
eight football players with a rare but potentially devastating hip
injury suffered by American football players, and they have offered
their recommendations for diagnosis and treatment of the injury.

The
researchers said that prompt diagnosis and proper treatment of hip
subluxation – which in many cases is dismissed simply as a hip "sprain"
or "strain" – is important because it appears that up to 25 percent of
such injuries may lead to bone death within the hip joint.

Subluxation
is a partial dislocation of the joint. In a complete dislocation, the
"ball" at the top of the femur which rotates within the hip joint pops
completely out of the joint. In subluxation, the ball moves in and out
of the joint without tearing the capsule surrounding the joint. Hip
subluxation is the injury that forced Oakland Raiders running back Bo
Jackson to retire from football.

"Hip subluxation is an unusual,
although potentially devastating injury that is an inherent risk of
participating in American football," said Claude T. Moorman, M.D.,
orthopedic surgeon and director of the sports medicine program at Duke.
The results of Moorman's analysis were published this month (July 2003)
in the Journal of Bone and Joint Surgery.

"There is very little
medical information out there to guide physicians in how to best take
care of these patients," he continued. "This analysis is intended to
raise awareness of this injury, so that we can determine the best way
to care for these patients."

Although most players who are
properly treated can eventually return to the field, the injury can
lead to a condition known as avascular necrosis (AVN). AVN is caused
when the ball of the hip joint no longer receives an adequate supply of
blood. The resulting death of the bone causes the joint to collapse,
necessitating either an artificial hip joint or a vascularized bone
transplant.

While the number of players involved in the study is
small, Moorman said the study represents the first step toward
identifying the injury and helping physicians take better care of
patients. As the injury becomes better appreciated, Moorman expects
that more players in football, and even other sports like hockey and
basketball, will be diagnosed.

For their analysis, Moorman's team
--which included orthopedic surgeons at the Hospital for Special
Surgery in New York -- followed eight football players who sustained
traumatic hip subluxation over a seven-year period. Three of the
players played in the National Football League, one played at the
collegiate level and the remaining four were high school players. They
included four running backs, two linebackers, one wide receiver and one
lineman.

Two out of the eight players, or 25 percent, went on to develop AVN.

The
researchers examined the medical records, radiographic images, as well
as videotapes of the injuries to better understand how the injury
occurred and which treatments appeared to be most effective.

"In
six out of eight of the players, the injury occurred after a fall on a
bent knee with the hip joint popping out backwards," Moorman said. "In
all cases, the players suffered extreme pain and were unable to return
to the game."

The challenge for physicians is to diagnose the
subluxation, according to Moorman. Standard x-ray exams do not reveal
the tell-tale joint fracture characteristic of subluxation; only an
obliquely angled x-ray can detect it. However, Moorman's team found
that magnetic resonance imaging (MRI) can be helpful both at the time
of injury as well as later to detect any early signs of AVN.

"The
joint is encased in a capsule, and when there is subluxation, the
resulting blood and fluid buildup within this confined space appears to
put pressure on the blood vessels, potentially cutting off or limiting
the supply of blood," Moorman said. "In a complete dislocation, these
fluids are dispersed, so in this way, a partial dislocation can
possibly lead to a worse outcome than complete dislocation if not
diagnosed and treated."

Extreme buildup of fluids can be detected
early by MRI, allowing physicians to remove the fluids through a needle
to reduce the immediate pain and lessen the chances of AVN. Moorman
recommends that another MRI be performed six weeks later to detect any
early signs of AVN.

As far as treatment, the results of Moorman
analysis indicate that patients should stay on crutches for at least
six weeks, without putting any weight on the hip. If the follow-up MRI
reveals no early manifestations of AVN, the player can slowly resume
normal activities, he said.

"Six of the eight players studied
showed no signs of AVN, and they all eventually returned to their
previous level of competition," Moorman. "Another player never returned
to the sport, and the other played for three years against the advice
of physicians. Both have since required complete hip joint replacement."

Moorman
and colleagues in Duke's Orthopedic Research Laboratory are beginning
studies in animal models to better understand why subluxation causes
AVN while total dislocations do not.

The study was supported by Duke University Medical Center and the Hospital for Special Surgery.

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