Researchers Use Cadavers to Find Answers to Knee
Injuries and Preventive Actions
Study confirms no two knee joints are alike, finds
that female knees are more vulnerable
Sept. 9, 2009 – For senior citizens, knee injuries
can be devastating – an end to an enjoyable active lifestyle and the
beginning of a long battle with pain and obesity. Osteoarthritis
eventually gets most seniors as the protective cartilage lining on the
ends of bones gradually wears away. There is new hope, however, for the
most common knee injury – damage to the anterior cruciate ligament
(ACL).
Researchers seeking ways to prevent ACL injuries
have measured the strain placed on ligaments in cadaver knees during
simulated sports landing movements to show that no two knees respond the
same, and that injury prevention programs should be tailored to
individual athletes.
In osteoarthritis, taking oral ibuprofen is more
effective but has potential side effects: drug interactions with
aspirin, and GI complications for some people
By Lisa Esposito, Editor, Health Behavior News
Service
Currently, most ACL injury prevention programs are
based on gender and on large populations, said Scott Mclean, assistant
professor in the School of Kinesiology and lead researcher on a new
study.
McLean said this approach doesn't fully account for individual
knee joint differences and how gender influences these differences.
Women suffer ACL injuries eight times more than men
"We are taking the group-based prevention concept
and going one step further to begin to explore the idea of
patient-specific injury prevention training programs. We must turn the
focus from an overly simplistic, sex-based program, for example, to
programs and injury prevention strategies that account for individual
joint vulnerabilities," McLean said.
In the study, McLean and his former colleagues at
Cleveland Clinic torqued cadaver knees of both genders using a manual
loading device, and measured the force in the ACL. They then developed
mathematical models from the data to examine differences between male
and female ACL injury risk for specific movements.
The researchers found that female ACLs stretch more
for a given force than male ACLs, likely due to differences the way the
ACL and joint are designed. Injuring the ACL, one of the four major
ligaments of the knee, often requires surgery and a long, painful
recovery. Later in life an ACL injury can cause osteoarthritis and lack
of mobility, which can lead to obesity, diabetes and other problems.
The study also confirms that no two knee joints
are alike.
McLean says individual knee geometry is a large
part of the ACL injury equation. The study's results showed that male
and female ACLs are loaded very differently during sports movements
based on the amounts of strain placed on the cadaver specimens.
"We've always needed to clarify underlying causes
or mechanisms of ACL injuries before trying to successfully prevent
these injuries in both men and women. This study demonstrated that
tailoring injury prevention programs to individual joint risk factors
may be an important and necessary step," McLean said.
"This research is the first step in helping team
physicians and trainers prevent injuries by becoming more aware of the
fact that female knees are more vulnerable," said A.J. (Ton) van den
Bogert, professor with the Cleveland Clinic Lerner Research Institute,
and study co-author.
"We hope this can be made more applicable by
determining the vulnerability of the knee through methods that can be
applied in athletes. Continuing this research with computer models based
on detailed MRI images and mechanical stiffness tests on athletes' knee
will make that possible."
McLean, who also has an appointment at the
University of Michigan Bone & Joint Injury Prevention & Rehabilitation
Center, has begun to develop patient-specific computer models based on
MRI and CT scans which are fed with an individual's movements. He said
that such models could drastically improve ACL injury risk-screening and
prevention methods of the future.
"We could take a youth soccer team of 20 players
and assess their ACL load response to various sports movements with
their very own computer model," McLean said.
"From the results, we may find that only 10 youths
need targeted training because they were identified by the models as
more at risk for injury."
The study was funded in part by NFL Charities and
the National Institutes of Health.
Preventing and Treating Cruciate
Ligament Injuries
● An anterior
cruciate ligament (ACL) injury is usually caused by a sudden twisting
motion in the knee when an athlete lands or steps.
● Young women are
two to eight times more likely than young men to injure the ACL.
● Landing on the
balls of your feet, rather than flat-footed, may help prevent ACL
injuries.
Prevention:
The anterior cruciate ligament is most often stretched or torn (or both)
by a sudden twisting motion (for example, when the feet are planted one
way and the knees are turned another). Although ACL tears are usually
difficult to predict, their occurrence may be made less likely by
thoroughly warming up before sports, learning to land on the balls of
the feet (not flat-footed), and using strength training to make the
muscles firmer.
Symptoms: You may
hear a popping sound, and the leg may buckle when you try to stand on
it. After the initial painful rupture, the knee develops swelling, which
typically lasts three to four weeks. Once the swelling subsides, the
athletes usually don't experience discomfort or giving-way with
activities of daily living. However, with return to sports, the knee
often buckles, causing more damage to the knee.
Diagnosis: The
doctor may perform several tests to see whether the parts of the knee
stay in proper position when pressure is applied in different
directions. A thorough examination is essential. An MRI is accurate in
detecting a complete tear, but the only reliable means of detecting a
partial one is arthroscopy (a small surgical incision through which a
surgeon can use a tiny lens to see the tear).
Treatment: Surgery
to repair the ACL tear is usually followed by physical therapy over a
period of from six to 12 months, depending on the tear.
Glossary:
Ligament A band of
fibrous tissue that connects two or more bones at a joint.
Tendon Fibrous
cords of tissue that connect muscle to bone.
Meniscus A
C-shaped piece of cartilage that acts like a pad between the femur
(thigh bone) and tibia (shin bone).
