By Denise Vidal The relationship between the thigh bone and the hip socket is known as a ball and socket joint. A ball and socket joint is different than other joints in the body in that it allows movement in all different directions. For example, unlike the hinge joint of the knee, which moves predominantly forward and backward, the ball and socket joint allows the thigh bone to move forward, backward, sideways, and around in rotation. In the last few blogs we have discussed, among other things, the thigh bone's ability to roll in the hip socket. Speciï¬cally, in the downward dog movement (or Pilates' knee stretch), we focused on the thigh bone's ability to roll forward and backward. However, as I have mentioned before, the healthiest joints are those that experience their full range of motion. Therefore, in today's blog we will explore movement of the thigh bone in a different direction. To begin, lie on your left side. Your bottom (left) leg will be bent, while your top (right) leg will be straight. In this position, your head, tail, and right foot should be in alignment and your pelvis should be stable. If necessary, you can put a pillow under your head. Next, inhale through your nose and feel your abdomen expand. In your mind's eye see your breath swirling down to the base of your pelvis. As you exhale, see your breath swirling up into your ribcage as your abdominals contract. Use this abdominal tone to keep your pelvis stable during the exercise. On your next exhale, lift your right leg. As you do this, the top of your thigh bone, the "ball," will move in opposition to the foot. In other words, the top of your thigh bone will roll inward in the hip socket as the foot ï¬‚oats off the ï¬‚oor. As you place the foot back down the thigh bone will roll outward in the hip joint. Continue to lower and lift the leg eight times. When you have ï¬nished, lie on your back with your legs straight and feel the difference between your two legs. When you are ready, roll onto your left side and repeat the exercise with your left leg. Just a reminder, if you experience any pain during this exercise, do not continue. If your pain persists, contact your Doctor or PT before resuming any exercise routine.