Time for a sports
subject again… This post is about pain in the patella tendon, usually known as
Jumper’s knee, but the correct medical term is actually Patella tendinitis.
Some background
information;
Jumper’s knee is an
overuse injury that is common in the sport of volleyball, but also in
basketball.
The etiology (reason)
for the injury is still not completely analyzed/researched or understood
enough, so the reason is not yet known. Earlier studies have shown risk factors
like jump height, mobility, age, gender, a high load of game exposure and a lot
of jumping.
During last year I did
a literature review in a sports medicine course, the purpose
of that study was to present the latest evidence within biomechanical risk
factors for the development of jumper’s knee. I thought I would try to share
the result.
So, what are
biomechanical risk factors?
Biomechanics is the
science of such a simple thing as how two joint surfaces moving in relation to
each other, but it’s also as complex as how the body is used as a whole, and
the forces it’s subjected to. Biomechanical risk factors would then be
movements in the joints that can cause damage.
Knowledge I want to share with you;
I looked into new
research in the subject of jump and landing technique with advanced analysis
and descriptions of the forces on the joints and tendons, angles of the feet,
knees, hips and back. It was really interesting to read, though it took some
time to get into the subject. It’s not so easy to analyze research, as the
result is so dependent on the method; is it reliable and are the statistical
methods right? When reading research you HAVE TO understand this type of
analysis, as there are so much research with interesting and amazing results,
but unfortunately they’re not reliable.
In a lot of studies I found that many used analysis of a two legged landing after a jump down from
an elevated position. A lot of people would think; yes, why not? It’s the
landing they’re interested in analyzing. OK, yes, but the force and the landing technique is totally different depending on how the jump is done, and very seldom
athletes land with the force directed strictly downward after a jump as the jump normally isn't directed only straight up. This
makes these studies unreliable as to the outcome and explanations for jumper’s
knee, since the landing isn’t specific for the sport.
The athletes used for
the research were mixed, but mostly volleyball and basketball players,
athlete’s with previous history of jumper’s knee, athlete’s suffering from
jumper’s knee at the time for the study, and usually a control group with no
history of knee injuries.
I found some real
interesting results, and not only of the landing, but also when it comes to the
take off for a jump, and some other findings...
The result show;
- Range of motion in the ankle for dorsiflexion is very important
- Increased velocity of flexion of the hip and back in landing
- Increased velocity of loading for the quadriceps muscle in the deceleration phase in the countermovement motion preceding a jump
- The angle of the knee and ankle (lesser degree of plantarflexion) in initial ground-foot contact in the landing
- The flexibility of the Quadriceps, tighter muscle means greater risk
- The anatomical position of the feet in standing, neutral position meant smaller risk for jumper’s knee.
Conclusion; Several
biomechanical factors in the landing technique and mobility of the joints and
anatomical position of the feet affect the load on the patellar tendon and
predispose jumper’s knee.
So to avoid the problem, work against all of these risk factors. Work on jumping and landing technique with the youngsters, work on the mobility in the ankles and the muscles and so on. As usual; there are no shortcuts!
So to avoid the problem, work against all of these risk factors. Work on jumping and landing technique with the youngsters, work on the mobility in the ankles and the muscles and so on. As usual; there are no shortcuts!
Video: see the movie here.
Landing with plantar flexed foot compared to lesser cushioning and lesser degree of flexion
Long vs short landing
Long vs short landing
Velocity of flexion of the hips and core in the landing
Countermovement phase in the stop-jump
Please have in mind that when the research was done, they used highly advanced technique to be able to follow the movements and measure exact angles, so it is difficult for the eye to see, but I did my best to try to show it on the video.
Pictures:
