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the JOINT segments of the LEG

 

Where should the knee point in standing postures like Warrior (Virabhadrasana) Or in Squat (Malasana)? Where should the feet point? Can every one do Lotus (Padmasana) safely? Is there always a risk if someone hyperextends their knees?

HIP joint

 

The hip joint is the meeting of the ball at the top of the FEMUR (femoral head) with either side of the PELVIS (acetabulum).

The femur (thigh bone) is the longest and strongest bone in the body. The femur has many twists and turns which help determine the ultimate potential range of hip joint motion for a variety of movements. The femoral head (ball) is at the end of the short section of bone called the femoral neck. A large bump juts outward from the top of the femur, next to the femoral neck. This bump, called the greater trochanter, can be felt along the side of your hip.

 

Variations of the femur :

  • Femoral torsion (twisting along the shaft of femur)Every long bone in our body has a slight rotation to it. In the femur we call this twisting femoral anteversion. If there is only a small twist, no twist or a negative amount of twist it is called femoral retroversion. In general, and all other things being equal, people with less torsion will find it easier to externally rotate their femur in the hip socket (Lotus - Padmasana) and those with higher will find it harder to externally rotate, but easier to internally rotate (Eagle - Garudasana) The degree  of anteversion / retroversion will also contribute to the natural positioning of the feet. 

  • Femoral neck shaft angle (turn occurring between the shaft & the neck of the femur) : Femur neck angles can vary greatly, the wider the angle the greater potential for abduction at the hip socket. 

  • Length of neck Neck length is a factor in the range of motion available before the greater trochanter squeezes against the side of the pelvis. The longer the neck, the greater the range of motion possible. 

  • Size of greater trochanter : The larger the prominence of the greater trochanter, the sooner compression will be reached in abduction and the lower the greater trochanter, the more room you’ll have before compression occurs

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The femoral head fits into a round socket on the side of the pelvis. This socket is called the acetabulum. The key variations of the acetabulum that can affect our mobility and range of motion include: 

 

- Angles of the acetabulum relative to the 3 planes of the body

The shape of the acetabulum (including size,roundness, depth)

The verticality of the anterior pelvic plane.

 

Acetabular depth : If the acetabulum is shallow, a greater range of motion in the hip socket is possible, however it is subject to more stress as the amount of surface that supports the weight of the body is smaller.

The APP is formed by points of the ASIS and pubic tubercle. It was long believed everybody had a perfectly vertical APP. When the ASIS juts forward = pelvis anteversion, backwards is called retroversion of the pelvis. This plane is not a reliable indicator of wether or not the pelvis is tucked. The orientation of the pelvis by the slope of the sacrum is better.

The bony ridge that forms the acetabulum is covered by a cartilage lip called the LABRUM, which essentially extends the acetabulum and adds stability to the joint. It is also associated with managing stress coming into the joint as well as helping to seal the joint. The extra depth to the acetabulum created by the labrum can also restrict movement and sometimes if the labrum is too thick, it pinches in, causing impingement problems. It can be injured and cause pain and clicking in the hip.

The femur is bound to the pelvis by LIGAMENTS surrounding and inside the synovial joint capsule of the hip joint. They are particularly strong and dense, reinforcing the joint in a variety of directions. These ligaments are the main source of stability for the hip. They help hold the hip in place. As in many places in the body there is debate as to how much each ligament restricts movement in a particular direction. 

 

A long tendon band runs alongside the femur from the hip to the knee. This is the iliotibial band. It gives a connecting point for several hip muscles. A tight IT BAND can cause hip and knee problems.

The potential range of motion for the hip is tremendous considering its location, the amount of weight it supports and the force it generates. The hip joint is referred to as a ball-and-socket joint that allows the ball of the femur to spin (in flexion & extension), roll and a bit of sliding (abduction, adduction,  external/internal rotation) in the cup of the hip socket.

Just because a joint has the potential to move in all these directions doesn’t mean that it does. 

Muscles causing and restricting hip movement varies depending on the orientation of the thigh to the pelvis. From an anatomical position :

Compressive restriction to movement can occur in 4 areas around or in the hip joint (assuming the tensile resistances of fascia, muscles, ligaments and joint capsules are no longer inhibiting the movement needed to reach compression) : 

 

  • Soft compression - abdomen or chest hitting the thighs

  • Medium compression - tissues caught between the front of the pelvis (ASIS) and the thigh (bone hitting flesh)

  • Medium compression - tissues caught between the greater trochanter and the side of the pelvis (ilium) which results in 2 bones trapping flesh between them.

  • Hard compression - neck of the femur impinges upon the labrum of the acetabulum (bone on cartilage compression) 

 

The hips see a lot of variation in bone shape making the determination of hard compression most challenging. There are a great deal of variation in the angles that come together at the hip and both sides are likely to be different.

MENISCI - Due to the shape of the knobbly ends of the femur, and the relatively flat surface of the top of the tibia, between these 2 bones are the meniscus : The menisci are 2 (lateral and medial) semi circular pieces of cartilage. They create a deeper cup, for greater stability, they also play as a shock absorber and help with the knees functional movements, where they move and distort in shape. Meniscus tears are common in yoga, wether originally from the asana practice or exacerbated by it. Poses such as Lotus (Padmasana) where forced rotation at the hip can transfer stress to the knee when the foot is held in place, by the floor or another part of the body.  

Unlike most joints, there is no bony stop to limit movement; instead, ligaments, tendons, fascia and muscles combine to resist hypermobility. 

  • The Anterior Cruciate Ligament (ACL). The ACL connects the tibia to the femur and functions to prevent the tibia from sliding forward on the femur. The ACL is commonly injured and rarely in isolation.

  • The Posterior Cruciate Ligament (PCL). The PCL also connects the tibia to the femur. It functions to prevent the tibia from sliding backward on the femur. It can become injured in hyperextension.

 

These strong ligaments are the primary stabilisers of the knee. They prevent the femur from slipping off the stationary tibia. Cruciate means ‘crossing’ this arrangement causes the two cruciate ligaments to wrap around each other when the tibia is internally rotated under the femur. When the tibia externally rotates under the femur the two cruciate ligaments move away from each other allowing more range of movement.

The strap like collateral ligaments (medial MCL and lateral LCL) connect the femur to the tibia. The collateral ligaments help to prevent twisting and side movements of the tibia under the femur when the leg is fully extended. When the knee flexes the collateral ligaments are slightly lax allowing for postures like Lotus (Padmasana)

  • The Lateral Collateral Ligament (LCL). The LCL, which is also known as the fibular collateral ligament, is located on the outside (lateral side) of the knee. It connects the outside, bottom edge of the femur to the outside, top edge of the fibula. The LCL helps stabilise the knee joint by limiting outward (varus) force across the knee. 

  • The Medial Collateral Ligament (MCL). The MCL is located on the inside (medial side) of the knee, connecting the inside, bottom edge of the femur with the inside, top edge of the tibia. The MCL helps to stabilise the knee by limiting inward (valgus) force across the knee. The MCL works with the LCL to prevent unwanted side-to-side motion. The MCL is the most commonly injured knee ligament.

 

KNEE joint

The femur, tibia & fibula, meet the patella to create the largest joint in the body - the knee-joint segment. 

  • The knee must be strong, bearing a lot of body weight.

  • The knee must be flexible, enough to deal with the

     adaptations of the foot and the hip. 

Technically, the knee is made up of 4 separate joints:

  • the patella & the femur

  • the fibula & the tibia

  • the medial condyle of the femur with the tibia

  • the lateral condyle (expansion) of the femur with the tibia

THE TIBIA (shin bone) is the primary weight bearing bone of the lower leg, The secondary being the FIBULA.

 

THE FEMUR (thigh bone) is both the longest and strongest bone in the human body. 

 

THE PATELLA (kneecap). The patella sits at the anterior-most (front) of the knee joint. 

The knee supports the weight of the body so there is a lot of compression of the femur onto the tibia & of the patella onto the end of the femur. These areas of compression generally do not limit range of motion. The stress of doing too much or not enough can lead to pathology. 

 

The knee is highly influenced by and connected to the joints above and below it. - the ankle and hip. Often when injury occurs at the knee, there is some level of dysfunction, (excess tension or weakness or even a previous injury) in one or both of these surrounding joints.  The knee being the central link is responsible for guiding and directing the movements of our leg in our daily activities. 

MOVEMENTS OF THE KNEE 

The knee moves predominantly in flexion and extension, which is why it is often called a hinge joint. (like a doors hinge, opens and closes) However, when the knee is flexed, other directions of the knee are possible, which is why it is often referred to more complex names such as a condyloid or ellipsoid joint. 

EXTENSION & HYPEREXTENSION - When the knee is locked, in a close pack position, the knee is almost invulnerable to injury. 

 

The knee is said to be fully extended when the leg is completely straight, but more movement beyond straight is available. This is called hyper extension, and it is normal and natural. By normal we mean that over 95% of people can and do hyperextend their knees. By natural we mean that this is a necessary movement for the knees and helps to reduce constant contraction and contracture of the quadriceps. The average person can hyperextend their knees 5 to 6°

 

It’s okay for most people to hyperextend their knees in static yoga postures, for some people it may be dangerous. To protect knees at risk we can reduce hyperextension, but this may prevent a stress needed to keep the knees healthy. One way to combine both intentions is to use Yin Yoga practice to stress the joint safely and passively and use a yang practice to stress the musculature of the body while refraining from hyper extension. - We can soften the knee and employ co-contracting of the Quads and Hamstrings.

In general resistance to extension would be due to the fascia (SBL) (DFL) and the muscles (opposites  of chart muscles that moves the knee.) 

FLEXION -  When the knee is flexed, it is more vulnerable as the surrounding ligaments lax.

 

Sitting on your heels requires 160 to 170° of flexion sitting in between your feet requires 170 to 180°. The average person cannot sit on the heels let alone sit in between their feet due to the average persons range of flexion at the knee joint being between 125 to 160°. Some people will never be able to do these poses due to compression of the tissues in the back of their knees, calves and thighs. 

In Yoga we often hear the cue - that the knee must stay over the ankle, (in Lunges and Warrior Poses) to prevent stress on the knee. This rationale ignores the fact that all tissues need stress to stay healthy. In everyday life, we constantly allow and require our knees to go forward of our ankles. When we climb stairs, for example. This cue is more likely based on aesthetics, as in most there is no danger in allowing the knee to come forward of the ankle.

 

In Warrior 2 for example, having the knee go past the ankle will require the quadriceps to work harder to maintain this position, the stress in the knee is safe and may be required to keep the knees healthy. However, for students who have pre-existing knee issues it may be wiser to reduce to a 45° angle of the thigh to the horizontal. This can be achieved by narrowing the distance between the feet - taking a shorter stance.

 

In general resistance to flexion would be due to the fascia (SFL) and the Quads muscles (opposites  of chart muscles that moves the knee.) Fleshy compression can occur. 

 

ROTATION - The knee can permit moderate amount of rotation between the tibia and femur. This twist is allowable when the knee is flexed, which loosen up ligaments that restrain rotational movements when the knee is fully extended. This accommodates the movements of the hip and foot. How much rotation available without harm depends on the length and laxity of the persons ligaments .Sudden or excess movement in theses motions can tear one of the supporting ligaments or cartilage. 

Postures that require a lot of internal/external rotation at the hip joint, such as Hero Pose (Virasana) or Lotus Pose (Padmasana) If the femur cannot rotate, twisting will occur at the knee, and the tibia rotates.  Do not try to compensate by over stressing the knee joint. Find a moderate position where there is no pain. In the above Hero Pose (Virasana) The student allows her feet to point out due to large internal rotation at the hip sockets, for her there is no rotation at the knee and so no risk to the knees. She is comfortable. 

 

'SIDEWAYS' movement of the knee ; there are no muscles that cause the knees to draw inwards or outwards of each other, the movement may occur as a result of other movements of stresses such as abduction or adduction at the hips when feet are planted to the ground. In general resistance to sideways movements would be due to the collateral ligaments and joint capsule. The Lateral Lines of fascia can work with or against the Deep Front Line to either create side-side stability or cause valgum or varum problems. The SPL helps with proper tracking of the knee. 

 

VALGUM - Knocked Knee

VARUM - Bowed Legs

The relative positioning of the knees is determined by the Q-angle (the line of the femur and a vertical line through the patella.)  If the angle is large, the knees tend to bend in towards each other (valgum) This makes the person unable to bring their feet together when standing as the knees knock. If the Q-angle is 0 or less, the knees bow away from each other (varum) The Q angle is affected by the shape and twist of the bones - femur, pelvis, tibia. 

Having these alignments doesn’t automatically result in problems. Many people do not suffer from problems at all. Others, extreme valgum can place a lot of stress on the medial side of the knee and on the other side, varum can stress the lateral. There is not a known cure but exercises can help people deal with the effects. 

Many anatomical and behavioural factors can lead to varum or valgum: pelvis width, acetabulum orientation, femoral torsion, tibial torsion, ankle and foot structure, ligament laxity, quadriceps weakness, proprioception deficiencies, pronation or supination of the feet, and other habitual movement patterns, 

 

The causes within our control include; weakness in the hip abductor and external rotator muscles (3 glute muscles) and/or over activity of the adductors; pronation of the foot, which can be caused by a restricted range of dorsiflexion; weakness in the quads (vastus medialis obliquus; and weakness in the semi-membranosus and  semitendinosus hamstrings.

 

 
 

The observation alone, that a students knee isn’t tracking the foot should not be used to correct a student. A deeper inquiry is needed - Is there pain? Is the foot pronating? Does the student have a knee pathology? Arthritis? Are they valgum/varum? If so is this due to anatomical structure or muscular weakness? Correcting someone without understanding why can lead to more problems than the student currently has. It is ok for many students to have their knees pointing inside the foot for Warrior 2 (Virabhadrasana 2)

In Mountain Pose (Tadasana) it can be helpful to check the natural alignment when a student stands. If only the knees come together (valgum), or the feet are together (varum) expect the knee/foot in other postures to also not be aligned. Another way to determine wether it is their natural position is to check what’s happening at the foot in say Warrior (Virabhadrasana) If the foot is pronated, then there is a good likeliness that the valgus can be corrected. The degree of pronation/supination may be subtle and so hard to see. If the foot is neutral, regardless of what the knee is doing, there may be no need or point in correcting. 

 

 

ankle / FOOT 

 

The lower we go, the more important stability becomes. The whole body’s weight is supported on our ankles, the foot has to be stable, it’s our foundation. Mobility here though, is just as important.

 

The foot has to adapt; to changes and movement of the joints that are above it, absorbing & distributing the bodies weight; to changes in the terrain beneath it.

 

The HIND FOOT. The ankle joint is formed by the connection of three bones : The ankle bone is called the talus. The top of the talus fits inside a socket that is formed by the lower end of the tibia (shinbone) and the fibula (the small bone of the lower leg). The bottom of the talus sits on the heelbone, called the calcaneus.

Getting the feet strong, flexible, balanced, aligned, rooted, and resilient, is a basic starting point for building or guiding practically any yoga practice, including seated meditation.

 

The FORE FOOT - Contains the 5 toes (phalanges) and the 5 longer bones (metatarsals). 

 

The MID FOOT - is a pyramid-like collection of bones that form the 3 arches of the feet. The ligamentous and fascial connections, and the  musculature in the front, back and sides of the calf, help maintain the arches and create a foot foundation. (The Achilles’ tendon transmits power from the calf muscles to the heel and the foot. This makes it possible to flex the foot, crucial for toe off of the foot when walking  and running.)

 

The arches give us our springiness. They reduce the amount of energy we need to expend. The arches become loaded, converting kinetic energy of walking into potential energy and releasing this stored energy back into movement. 

 

  • Medial : the familiar arch on the middle side of foot, is very important for propulsion.

  • Lateral : the not so obvious, outside foot arch, is very important for weight bearing. Unlike the medial, this arch contacts the ground.

  • Transverse :runs across the front of foot. Together these arches form a triangle. 

Essentially we’re standing on a triangle with one point at the base of the big toe, one at the base of the little toe and one at our heel. Take these three points and connect them to the top of the ankle joint and now we’ve created a pyramid, a very stable structure to be standing on. When we root down into the three points, the arches natural lift into a triangular dome shape. This action is called Pada Bandha (foot energy lock) 

 

When we stand, the weight of our body is distributed among these 3 points, but the heel receives most of the weight, which is why it is thicker and more padded. 

The ligaments keep the arches springy. If the ligaments become lax or their bones loose their alignment, the arch collapses. - fallen arch or flat foot. There are 2 versions of this, a flexible flat foot and an inflexible version where the bones of the hind foot have fused or were never separated in the first place. In the other direction, we have a condition with a high arch ‘claw foot’. This is often neuromuscular.

 

Another affect of arch height is the relative positioning of the heel behind the ankle. If the ankle is more over the heel the body’s center of gravity is precariously far back; this requires the body to lean forward, which could lead to tightness in the superficial back line meridian of the fascia and joint problems in the knees and ankles.  Thomas Myers believes that a ratio of 1:3 between the hind foot and the forefoot provides the most effective support. A ratio of 1:5 however, may result in minimal support.

 

PADA BANDHA 

 

Explore the 3 points of each foot: the ball of the big toe, ball of the little toe and middle of the heel; and root down into them equally, while at the same time feeling a lift in the arches. 

 

Activating pada bandha is key to stability in all standing poses. Bandhas are used to draw the energy upward. Pada banda supports the lift of the arches and the optimal alignment of the joints in the legs and the pelvis. 

 

The feet do not stand alone, nor do they independently support movement so activation of the feet begins in the legs as we run lines of energy from the top of our femur bones down through our feet. This creates a “rebounding effect.” When you intentionally root down from the tops of your thighbones down into your feet, the muscles in your calves and thighs engage. This not only creates the upward pull on the arches of pada bandha but creates expansion through the joints and a sense of being more firmly grounded yet resilient in your feet while longer and lighter up through your body.

Lift our toes to lift our arches - when the toes lift up, the tension in the plantar fascia is increased and the arches of our feet lift. As a result, the heel and ball of foot move closer to one another. Play with arch collapse and feel the affect on the knees and hips.

 

MOVEMENT 

 

The shape of the bones allows for plenty of forward and backward movement & limits side to side movements. 

  • Dorsiflexion: the top of the foot moves toward the knee

  • Plantar flexion: the sole of the foot moves toward the calf

  • Eversion: the outside of the ankle moves toward your hip

  • Inversion: the inside of your ankle moves toward your groin

  • Abduction: a movement at the ankle causing the toes to move away from the body

  • Adduction: a movement at the ankle resulting in the toes moving in toward the midline

When you combine dorsiflexion, eversion, and abduction, your foot pronates; when you combine plantar flexion, inversion, and adduction, your foot supinates.

POINT OR FLEX?

 

Dorsiflexion causes greater stability in the ankle joint as the wider part of the wedge shaped talus bone is lodged in the space between the tibia and fibula. The particular shape of this bone is highly variable and can determine our ultimate limit to dorsiflexion. Trying to force the talus too deep, too quickly can sprain or rupture the ligaments joining the tibia and fibula.  

 

In plantar flexion, the narrower part of the talus moves into this space, creating less stability but an easier sense of radiating energy out through the feet. (Warrior 3) The lack of stability is one of the reasons most ankle sprains occur when the ankle is plantar flexed. 

 

Sickling of the feet - There may be many reasons why sickling of the foot occurs, and this position of the foot may be quite normal and safe for the student. If you are concerned, ask the student what are they feeling in their knees? If there is discomfort or pain in the ankle, knee or hips, suggest they try straightening the foot and see wether that helps. If they are nicely grounded already, firm and solid in the posture, then why try to correct their natural alignment. Remember the intention of the pose, focus on function not appearance.

 

FOOT & POSTURE

 

Basic posture starts at the feet, everything else is stacked above. If our bodies are in good alignment, the line of gravity flows right through the centre of our body. The further our body moves away from this alignment, the more tissues of the body will have to respond to maintain an upright position in relation to gravity. Over time the stresses and strains of misaligned bones can lead to chronic pain. 

 

"A man's tracks tell quite a true story. They inform quietly about ankles and knees, but they shout the news about hips and pelvis. If one foot is consistently everted [tilted onto its inner edge], the ankle, the knee, or, perhaps more likely, the entire pelvic basin is rotated." - Ida Rolf

 

In standing yoga postures, note where we place the feet relative to one another. How far apart and how they align with one another, where the weight is distributed affects the structure and then the posture above them. - Where we position our feet will impact where and how we position our pelvis. The more open our tissues are around the hip joints, the more adaptable the position of the pelvis relative to the feet. Also the body parts above the pelvis compensate for the positioning of the pelvis. 

 

To really tell where the feet naturally point we need to consider:

 

  • What is going on at the hip joint

  • Torsion of the femur

  • What happens at the knee joint

  • The torsion of the tibia

  • The orientation of the ankle

 

 

 

 

 

 

YOGA BAREFOOT 

 

For the most of the day, our feet are constricted and cushioned in shoes and rarely experience anything other than perfectly flat, hard surfaces. This prevents us from using our feet to their full capacity. Our proprioceptors in the ankle sense changes in tension and relative position and communicate this information to relevant muscles. With cushioned shoes and predictable flat surfaces, the sensitivity is lost or muffled, muscles are not used and we end up with weak feet. Fortunately yoga is practiced bare foot.

 

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