Knee osteotomy is commonly used to realign your knee structure if you have arthritic damage on only one side of your knee. The goal is to shift your body weight off the damaged area to the other side of your knee, where the cartilage is still healthy. When surgeons remove a wedge of your shinbone from underneath the healthy side of your knee, the shinbone and thighbone can bend away from the damaged cartilage.
Imagine the hinges on a door. When the door is shut, the hinges are flush against the wall. As the door swings open, one side of the door remains pressed against the wall as space opens up on the other side. Removing just a small wedge of bone can "swing" your knee open, pressing the healthy tissue together as space opens up between the thighbone and shinbone on the damaged side so that the arthritic surfaces do not rub against each other.
Osteotomy is also used as an alternative treatment to total knee replacement in younger and active patients. Because prosthetic knees may wear out over time, an osteotomy procedure can enable younger, active osteoarthritis patients to continue using the healthy portion of their knee. The procedure can delay the need for a total knee replacement for up to ten years.