In addition to this ,the damage under the knee cap does not allow any pressure to be applied to it when the knee bends, because it is so painful. These factors cause one to have pain enough, that one gets off the knee very quickly. This is the primary reason for one to walk with a limp. Stair climbing machines are detrimental. Leg lifting apparatuses at gyms or health spas are dangerous.
Leg presses are to be avoided at all times.
Swimming using the breast stroke kick, hurts and should not be done. All of the above activities can cause more damage to the already damaged cartilage. Usually MRI exams do not show the damage to the cartilage under the knee cap. Quadriceps strengthening exercises . The exercises cannot be done when the knee is bent or the knee being lifted from the bent position.