Anyone who’s experienced “runner’s knee” knows it’s a painful and
debilitating condition that greatly impacts day-to-day physical activities.
This chronic condition characterized by sharp or radiating pain around the
kneecap afflicts millions of people, from marathon runners and martial artists
to high school students and housewives.
shows that 15 to 33 percent of active adults and 21 to 45 percent of
adolescents suffer from runner’s knee; those who do a lot of knee-bending
activities — walking, biking, squatting or jumping — are more prone to be
affected; and females tend to develop the condition more often than males.
Despite the high prevalence of runner’s knee, until recently, little research
has been done to pinpoint its exact causes or how to prevent it.
Michelle Boling, assistant professor of Clinical & Applied Movement
Sciences at UNF, has spent several years researching this musculoskeletal
disorder, also known as patellofemoral pain syndrome, or PFPS. The purpose of
Boling’s ongoing research, conducted by observing and collecting
motion-analysis data on thousands of physically active people in controlled
settings, is to determine the risk factors for developing PFPS and the role
gender plays in the prevalence and incidence of the condition. Another intended
outcome is to identify injury-prevention techniques to help healthy people
avoid developing PFPS and reduce additional potential health problems that
typically follow the disorder.
research involves looking at risk factors for patellofemoral pain, which is one
of the most common chronic knee injuries in runners and those we call ‘weekend
warriors,’” Boling said. “It develops over a period of time, and those who seek
rehab for it typically don’t ever get 100 percent better, so they end up
self-selecting themselves out of being physically active. This leads to a whole
cascade of problems later in life [including obesity, diabetes, hypertension
and osteoarthritis] so we really want to prevent PFPS early on.”
was part of a team of researchers that, in 2005, began to collect baseline data
and assessed the ongoing knee health of nearly 1,600 midshipmen enrolled at the
United States Naval Academy in Annapolis, Md. Boling said there were several
advantages to selecting this particular population: Researchers could assess
the participants’ health as they entered the academy as freshmen, including
only those with healthy knees at the onset of the study; all participants would
be required to take part in the same regular, strenuous physical activity as
part of their training program; both men and women would be studied; and the
subjects’ medical records would be easily accessible.
data collected included 3-D motion analysis during jump landings and
lower-extremity isometric strength tests and body alignment measurements
relating to the participants’ navicular drop (mid-foot/arch alignment) and Q
angle (the angle between the thigh muscles and the tendons of the knee). The
researchers looked at hip-rotation angles and strength of the muscles in the
lower extremities, as well as overall body mechanics during various movements.
All of these measurements were recorded to use later as a comparison/reference
when the inevitable knee injuries started happening.
we do is test healthy people and then we follow them throughout their four
years at the academy as they’re physically active to see who develops PFPS,”
Boling said. “For those who develop it, we go back and see how they were
different from those who stayed healthy and didn’t develop an injury.”
expected, a number of participants in the initial study were later diagnosed
with PFPS — 24 women and 16 men, according to medical records — and the team
set to work analyzing data, formulating hypotheses and determining risk
now know that people with weak thigh musculature, the quadriceps and
hamstrings, are four to five times more likely to develop patellofemoral pain,”
Boling said. “We also found that people with fallen arches, a measure of
navicular drop, have 3.4 times greater risk of developing patellofemoral pain
syndrome compared to those without fallen arches, and individuals who had more
internal collapse of the femur, were about 1.5 times more likely to develop the
might sound like a bunch of mumbo jumbo to some, but this is the kind of
information scientists can use to develop PFPS prevention techniques to share
with athletic trainers and coaches working with athletes.
and her colleagues at the University of North Carolina at Chapel Hill, College
of Charleston, Uniformed Services University and the United States Military
Academy now have plans to expand their research base, thanks to a $145,000
National Institutes of Health grant she received in June. The grant will allow
the research team to nearly quadruple the number of participants in similar
studies over the next two years at additional facilities.
grant will allow us to expand to West Point [military academy] and the Air
Force Academy, so it gives us a little more power to say these definitely are
the risk factors that we’re seeing in individuals,” Boling said. “But it will
also allow us to analyze more specifically by gender, giving us enough power
statistically to pull out data from females alone and males alone to
investigate their gender-related risk factors.”
Darin Padua, exercise and sport science professor and director of the Sports
Medicine Research Laboratory at UNC, has worked with Boling since 2001 in
various capacities and now serves as a consultant for her current work.
research investigating risk factors for chronic knee pain in people who are
physically active can ultimately provide important information that helps us to
keep people physically active for long periods without experiencing negative
side effects,” Padua said. “As a result, this has huge positive impacts on the
overall health and well-being of our society.”
also has worked with 150 Northeast Florida high school student-athletes the
last two summers to look at the same type of data as it relates to adolescents.
“We linked up with the Brooks Center for Sports Therapy because they already
had relationships with Nease High School and Ponte Vedra High School in St.
Johns County,” Boling said. “We’ve been able to go out and collect some
preliminary data and try to develop relationships with the schools’ athletic
trainers and team physicians to see if the risk factors in a younger population
are the same as what we see in older, collegiate populations.”
research team works with students who receive sports physicals at their schools
in the summers, conducting similar baseline tests as the military cohort. Plans
are also under way to expand the research to include student-athletes from
Bishop Kenny High School in Jacksonville.
Hartley, a former UNF undergraduate student and current graduate assistant
athletic trainer at University of Kentucky Sports Medicine, worked with Boling
on similar research her senior year at UNF. “If there is an efficient way to
screen for [PFPS] factors during pre-participation physical exams, we may be
able to prevent these injuries,” she said.
said she’s focused on moving more toward prevention rather than rehab following
injury. “We’re trying to develop simple worksheets we can share with coaches
and athletic trainers to explain the movement patterns they may want to look at
to avoid injuries in the future. If we can prevent injuries before they happen,
that’s a very good thing.”
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