YOGAJOURNAL.COM 37ANATOMYIn 2007, I slipped while descending a steep trail in Shenandoah
National Park. I took a hard blow to the outside of my left
knee, shredding the lateral meniscus and articular cartilage and
dislocating the kneecap. I faced major surgeries to save the knee
from a partial joint replacement. My orthopedic surgeon was
upfront: Recovery would be long and arduous. More than anything
else, my mindset would be the key to my healing. That meant
I needed to cultivate a nurturing relationship with my knees.
Fortunately, prior to the accident I’d been a yoga practitioner
with a daily meditation habit for 19 years. Before surgery, I dedicated
an hour a day to channeling love and gratitude into my knees. By
the time I was wheeled into the operating room for the first of two
surgeries that ultimately restored the joint’s structure, the knee had
become my most beloved body part. I had learned to celebrate its
complexity and vulnerability, and to fine-tune movements to treat it
well. The knee is the body’s nexus of faith and duty: One of the first
things we do when we seek strength or mercy is get down on our
knees. We also drop to our knees when we pledge ourselves to
a path of devotion. Each knee is the grand arbiter of mechanical
forces received from the foot and hip. For better or worse, the knee
adjusts itself to balance and transmit the energies of impact, shear
(sliding forces), and torsion (twisting forces).
The knee is often described as a hinge joint, but that’s not the
whole story. To the eye, it resembles a hinge because its primary
movements are flexion (bending, to draw the thigh and calf toward
each other) and extension (straightening, to move the thigh and
calf away from each other). In reality, the knee is a modified hinge
joint. It glides, and rotates. This makes it more versatile but also
more vulnerable. Its range of motion becomes clear when you
compare it with the elbow. Bend and straighten your elbow several
times. The movement feels similar to opening and closing a laptop.
Try it again by moving between Plank Pose and Chaturanga
Dandasana (Four-Limbed Staff Pose). Now try Virabhadrasana
II (Warrior Pose II), placing your front hand on the inner part of
your front knee. Bend your front knee (flexion) and feel the thigh
bone, or femur, glide forward and rotate—moving the knee up
and out. Straighten your knee (extension) and feel the femur glide
backward and rotate—moving the knee down and in.
To keep stable, the knee relies on tendons, ligaments, cartilage,
and the joint capsule itself, not large muscles. Among standing
yoga poses, Tadasana (Mountain Pose) is most stable for the knee
because there is maximal contact between the end of the femur
and tibial plateau (the top of the tibia, or shin bone). Things go
awry, though, if you “lock” your knees. When we hyperextend—
and many of us do so without conscious thought—we excessively
squeeze the anterior, or frontal, aspect of the menisci (see
drawing), pushing the tissues backward, out of their natural
placement. Instead, practice standing with your knees in a “relaxed
straight”: stand and press back through one of your knees. Then
firm your calf muscles toward your shin bone. Notice how all your
leg muscles engage. Take your attention to the middle of your
knee. It should feel very stable. Practicing this action over time
will reeducate your muscles and correct hyperextension. Also,
the inner parts of the knee are larger, thicker, and deeper than
the outer parts. This anatomical asymmetry makes it normal for
the kneecaps to slightly glance toward each other in poses such
as Tadasana and Adho Mukha Svanasana (Downward-Facing Dog
Pose). Perhaps you’ve heard the cue to point your kneecaps directly
forward in straight-leg asana? Don’t do it; it can injure the knee
because it overrides the structure and function of the joint.
The knee is least stable when bent. When we flex our knees,
as in Virabhadrasana II, we have less contact between the femur
and tibia. When there is less bony contact, connective tissues
strain and become more vulnerable. The vastus medialis, the inner
muscle of the front thigh, is primarily responsible for keeping the
patella, or kneecap, in its femoral sulcus, the groove at the end of
the thigh bone. Ideally, we want the kneecap to slide smoothly
up and down that groove, so that the patella functions efficiently
as a fulcrum when we bend and straighten the knee. But the
vastus medialis is much smaller than the vastus lateralis, on the
outside of the front thigh. This strength imbalance in the front
thigh muscles, or quadriceps, can cause the kneecap to pull out
and up, creating pain in everything from walking to bent-leg
standing asana. Lunge poses often make it worse. But we can
develop balance between the muscles through “quad setting.” Sit
in Dandasana (Staff Pose) with a rolled towel under your knees,
toes pointed up. Press out through your heels. Then, press down
through your knees, leading with the inner knee. Hold for 10-20
seconds, release, and repeat to fatigue.
Remember, the knees, stuck in the middle, absorb energy from
the feet and hips. If you take them beyond normal rotation or put
too much pressure on them when bent, you increase the risk of
harming your ACL. In turn, several poses demand a high degree of
caution. Some I’ve stopped practicing altogether.- Bhekasana (Frog Pose): Places strain on the ACL and medial
meniscus because of torsion from trying to draw the soles down
and toward the outer hips.
Keep Your Knees Safe
Exploring how your knees move can lead to a balanced
relationship between stability and vulnerability, on and off the mat.
BY MARY RICHARDS