The Knee Joint – Simple Yet Complex
On the surface, the knee joint seems to be a simple “hinge” bending back and forth. However, if you take the time to look more closely at this joint, you will discover a much more complex mechanism.
The knee is made up of 3 compartments, a medial (inner) compartment, a lateral (outer) compartment and an anterior (front) compartment. This anterior compartment is another joint called the patello-femoral joint (knee cap). The bones that form this joint are the femur above, tibia below and the patella (knee cap) in front.
The knee joint has very little boney stability and relies a great deal on the ligaments, cartilage and muscles to provide the stability of this joint. Movement is produced by 2 key muscle groups, the Quadriceps (front of thigh), which extend the knee and the Hamstrings (at the back of the thigh) that bends the knee. The superficial calf muscle (Gastrocnemius) also crosses the back of the knee joint and is involved in bending the knee at times.
The cartilage or menisci are half moon-shaped structures which sit on top of the tibia in the medial and lateral compartments. They serve as shock absorbers and also deepen the joint to provide more stability and keep the femur from sliding off the tibia. 2 key ligaments inside the joint are the anterior and posterior cruciate ligaments. The anterior cruciate ligament keeps the knee from hyperextending and from rotating too much internally while the posterior cruciate essentially does the opposite. Two ligaments exist outside the joint and are called the collateral ligaments. There is a medial (inner) collateral which prevents your tibia from bending sideways laterally and the lateral (outer) collateral which prevents your tibia from bending sideways medially. The collateral ligaments are more commonly injured than the cruciate ligaments.
The patello-femoral joint acts as a pulley system for your Quadriceps muscle. The patella is imbedded in the Quadriceps tendon and attached to the tibia below through the patellar tendon. This gives your Quadriceps a better mechanical advantage to work with your knee as it bends. It is also important for the inner and outer fibers of your Quadriceps to work in balance to keep the patella tracking properly. Patello-femoral joint irritation and pain is common when this imbalance exists. Your Quadriceps also performs an important role in jumping by contracting concentrically while it aids in softening landings by contracting eccentrically.
The Hamstring muscles (of which there are three two inner and one outer) bend or flex the knee joint and help extend the hip along with the gluteal muscles. They also act as a “dynamic” anterior cruciate ligament and help to keep the tibia from sliding forward off of the femur.
These are the key structures of the knee joint that must work together to allow for normal operation of the joint under the large loads and stresses we put the joint through daily with all our activities. Dancing, of course, places huge demands on this joint and with the use of good technique and proper training in and out of the studio we can keep the joint healthy and lower the risk of injury.
How can I apply this to my teaching/dancing?
ALIGNMENT IS KEY!
- Remember the aligning our dots exercise? Postural and pelvic alignment has a direct effect on knee alignment – start from the feet and work your way up when assessing knee alignment.
Invest time in teaching proper alignment
- When working in ‘turned out’ or parallel positions, ensure that the knees are moving in alignment with the feet and hips. For some this will be a challenge, but its a worthwhile investment of your time. The investment will pay off tenfold when you see that your students are able to self-correct.
It IS about efficient and effective movement.
- Teach students to work within their own physical ability. Students are not built from a cookie cutter method (all physiques the same). Take the time to look at students’ physique and guide them to work within their own unique physique (encourage individuality!). This will optimize the efficiency of their movement, training more effective and efficient movement patterns over time.
Talk about the anatomy of movement with your teen and adult students.
- First, it is important that they have an understanding of why it is important to work within their own physique. Second, experience indicates that this gives them a deeper understanding and awareness of their bodies, which then translates into a more thoughtful work ethic in studio.
Be willing to adapt.
- No dance form or teaching method is perfect for every – body. Find ways to adapt tried and true methods to suit the bodies that you are teaching.
It is not about today.
- All of this awareness and prevention is less about preventing an injury today or tomorrow, and more about preventing injury over time. Whether dancing, walking, or running indoors/outdoors, improper alignment of the knees causes friction and wear in places where it is not meant to occur. In the long-term this can translate into worn out cartilage, meniscus damage, ligament damage, and chronic knee pain.
Remember that “An ounce of prevention = a pound of cure”.
Authors: Sam Steinfeld, Kevin Dyck & Janine Didyk, RWB Physiotherapy Team (article) and Jacqui Davidson, Founder AD4L (teaching considerations)