Factors that affect Internal and External Rotation of the Femur
- The amount of rotation is not only dependent on biomechanics and the state of your musculature and connective tissue in terms of tension and elasticity but on
- Structural possibilities made available due to skeletal patterns (such as the length of the head of the femur and the angle with which it inserts into the socket of the hip).
It is often difficult to ascertain what is going on in terms of the movements of the femur because it is heavily layered in facia, muscle, ligaments and tendons. It is harder to distinguish when the femur is under tension in the muscle and soft tissues or if it has reached the full range of movements because of joint compression and therefore no amount of holding a pose or pushing oneself deeper into it will help to open your hips more. It is important to discover for yourself how your own hips work which is why we will be examining this in class this week. Remember it isn’t terrible to compress bone – in Yin Yoga practice which we occasional do in class, we benefit greatly from gentle and slow compression of the connective tissue around the joints in order to re-elasticate them and thin the synovial fluid that has become thicken due to arthritic changes but it is definitely a slow progressive practice in which the force you execute in that posture changes if you have released all of the tension in the muscles and got to your point of compression.
The femur moves forward (flexion), backward (extension); outwards, away from the body (abduction); inward, toward the mid line of the body (adduction). If we turn the foot out, and the movement comes from higher up the leg, the femur is being externally rotated and as the foot comes in, the movement in the femur is internal rotation. The range of movement is dependent on the stretch in the muscles but also in the length of the femur, the angle in which it fits into the accetablumum; variations in size and angle of the pelvis and many other variables which may limit the poses you are able to obtain. It is generally easier to see what is happening higher up in the femur and it’s relationship to the pelvis if we look at the lower extremities. The knee flexes and extends and if it is bent, it will rotate a little bit as well. As we bring the foot in toward the midline, we want this rotation to start at the femur as the knee doesn’t take too kindly to being rotated from it’s own axis (it wasn’t designed for that)!!! In sitting with legs crossed, if your knees are up by your chin, your external rotation is less extensive than the Yogi next to you whose knees are flat to the floor. How much external rotation you can achieve is not necessarily limited by your muscles and connective tissue but by the length and angle of the head of femur bone.
Have a quick look at this video in which Paul Grilley (often called the forefather of Yin Yoga) the internationally acclaimed Yoga Teacher demonstrating in pictures (starts at 0:44) how the bone itself may differ:
According to this study, here is a correlation between decreased hip internal rotation and total arc of motion with hip, hamstring, and groin injuries in young athletes so this is not just a problem associated with ageing. From a biomechanics viewpoint (as opposed to the structural viewpoint concerned with the anatomy of the bones and joints themselves) anyone of any age will have marked internal rotation of the lower limb due to pronation of the foot (which is prominent in a quarter of the population). The downward pressure on the inside of the foot arch when the foot is pronated (ie the arch is collapsed) cause an internal rotation at the tibia (see this review) and this in turn leads to an internal rotation at the head of the femur which causes the knees to stick up when sitting crossed legged.