The link above is for an article by Justin Price, M.A. on alleviating knee pain.
Ouch! That's some serious knee pain!
The first thing to understand is knee function: the knee only functions in one plane, and that would be going straight forward or straight backward. In order for the knee to move in a different direction, other joints have to give in order to change the legs direction. Those joints that assist in angling the direction of the knee are the hip and ankle joints. If the muscles around these joints are weak or overused, then inflamation can develop, reduce range of motion to protect the area, and create unnecessary load on the knee. An overloaded knee can result in recruiting tendons for support, and the tendon most likely to suffer is the ilioptobial band (ITB), which is located on the outside of the knee.
The article mentions the benefit of using the BOSU balance trainer to increase the range of motion of the foot (and therefore movement of the ankle) to strengthen calves, and the rotational resistance will help strengthen hip and core muscles. The variable stability of the BOSU's surface is unique in it's design. The crescent shape allows its user to increase joint angles and strengthen muscles that would not normally get worked on a flat surface. It should be noted the tight calf (gastrocnemius) muscles can contribute to both knee pain and, eventually, lower back pain due to the strain on the hamstring muscles. The primary movement to help with the hip and ankle complex to strengthen the knee is the lunge. The variations on the lunge, such as those mentioned in the article, mimic real-life challenges to the contractile and tensile strength of the glutes, hamstrings, and calf muscles.
I teach a class with a BOSU Balance Trainer on Monday mornings, I use them regularly in my circuit training classes, and use them to challenge clients. Contact me for more information on how to get the most out of the Balance Trainer.