There has been a great deal of ground-breaking research done about this tiny bone, the knee-cap, that could lower long term wear-and-tear stresses on your knees. With the help of your physical therapist, this information is especially applicable if you have had a history of pain originating from the knee-cap. When your leg is perfectly straight, there is only a small amount of the knee-cap that touches the bone underneath. This means that the “contact area” between your knee-cap bone and the thigh bone is very small relative to when the knee is somewhat bent. When applying exercise loads across or perpendicular to a straight-leg, as in the leg-extension machine for example, a high stress (or high-force over small contact area) situation can result between the knee-cap and bone underneath. To better understand the impact of this, imagine placing your hand flat on a table, pressing down into the table, and sliding the hand across the surface. Now think of holding a needle in your hand. What would happen if you pressed the needle down with the same amount of force and slide it across the surface? Which could do more damage, the hand or the needle? What decreased was the “contact area” between the surfaces. This high-stress situation for the underneath side of the knee-cap can be significantly mitigated by, for example, simply not going to a full, straight-knee position on the leg-extension machine.
For more information or if you have questions, please feel free to contact me. (I love this subject!)
Anna Kotula, DPT
T 805.798.1408
6-15-2005
