It has really became a social norm to cross your legs when you sit, in particular for women. It has become a point of etiquette, especially if you are wearing a skirt or dress, to cross your legs when you sit. Also, watching your parents and friends doing the same sitting position has lead to this being a very normal position to sit in. Some of you may even be finding yourself doing this each and every time you sit down. Yet, you were never warned of the danger.
The danger comes when you analyze the biomechanics of this sitting position. In order to sit in this position, significant twsting occurs in the leg on top as it swings over the other leg. It rolls one of your acetabular joints (ball and socket joint in your hip) inward and the other one in the opposite outward rotation. It places stress on the inside and outside of both knees, along with compression on blood flow to the lower legs. When you are younger, this is a much more forgiving posture, but the longer that you hold this position, the more you sit this way, the more it impacts the integrity of your joints, and a lot of them.
The joints and associated ligaments that can be affected in time with this sitting position are numerous and include the knees, hips, pelvis, pubic, low back, and even the mid back region. As a chiropractor, it is not uncommon to notice pubic bone misalignment and adjustments to the pelvis, hip and lumbar regions extremely common when this sitting habit is frequent. Often you as the patient don’t see the rationale for your pain until it is brought to your attention, and by then it is obvious.
Be aware of your posture in all positions. Remember that your body enjoys balance and it is beneficial to keep unnecessary stress off of your joints. Some of those pains that you have been aquiring all along have had a cause. In this case, you might have been sitting wrong all along. Don't cross your legs.
Crossing your ankles is a nice alternative and quite a bit less stressful on your joints.