From the limited information you gave us, it sounds like:
Chondromalacia of the Patella
Chondromalacia of the patella is a condition of badly damaged articular cartilage (like the smooth, shiny, white stuff at the end of a chicken bone) under the knee cap. This problem usually happens when one falls directly on a bent knee or repetative weight bearing sports activities, such as basketball, tennis and weight lifting, etc.. After the knee is damaged the muscles in front of the thigh (Quadriceps) that controls the stability of the knee, becomes weak in a very short period of time, The reason for this, is the knee not being used normally due to pain.
When one falls upon the bent knee, or participates in the repetitive weight bearing sports activities, there is a great pressure phenomenon directly under the patella, causing the cartilage under it to either become crushed or fractured. This is a very painful condition especially when one puts any pressure on the knee when it is in a bent position such as, kneeling, squatting, going up, and especially, going down stairs, and walking down inclines. Sitting is uncomfortable. There is also quite a bit of pain getting up from a sitting position. After sitting for a while and one get up to walk, the knee is stiff and painful, causing one to limp for the first 10-12 steps and then it quiets down and one walk more comfortably. When in bed the knee usually aches.
When one walks down-hill the body's natural tendency is to fall forwards. One unconsciously leans backwards and bends the knees. At that point the quadriceps muscles have to contract so the knee doesn't collapse. However, the muscles are so weak that they cannot hold the knee from bending more. If the knee doesn't bend more, one will fall flat on one's face. 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.
The use of a bicycle (stationary or regular) is not recommended. 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. According to research the test is approximately 40% reliable.
Treatment-- Quadriceps strengthening exercises . The exercises cannot be done when the knee is bent or the knee being lifted from the bent position. The following are recognized as beneficial by the orthopedic community. (isometric quadriceps contractions).
With the leg in the straight out position, (lying down) contract the quadriceps muscles. (tighten the muscles that pull the knee cap upwards). The knee must be straight. Hold this contraction as strongly as possible for 15 seconds (by the clock). One should feel the muscles above the knee cap starting to burn. Then rest the muscles completely for fifteen seconds. Repeat this fifteen times and do it once a day. Once one is able to do this exercise EASILY once a day, then twice a day is recommended. Once in the morning and once in the evening.
Once one is able to do this twice daily, easily, then one to progreses to lifting weights. One starts out with ankle weights of 2-1/2 pounds. Lift the weight starting with the knee completely straight, lying down, and lifting a straight leg so that the foot leaves the floor or bed 3-4 inches. The other is bent so as not to put any pressure on the lower back.
Do this exercise as before. Lift and hold for 15 seconds then down and relax for fifteen seconds. Repeat this for a total of fifteen times. Once one can do this easily, (not the first time one lifts the weight 15 times), then add 2- 1/2 more pounds to the ankle weight and repeat the process. Again, once the five pounds are lifted EASILY, add another 2-1/2 lbs. Repeat this process until 15-20 pounds of weight is on the ankle. Hopefully by that time, the pain is less, and the knee can be more active.
At the beginning of the exercise program the knee may become somewhat more painful. Over the counter anti-inflammatory medication may be helpful. Five to ten days of the medication may be necessary. Instead of this medication, extra strength Tylenol, Excedrin, or a similar medication may help reduce the pain. The use of an ice pack around the knee for fifteen minutes before the exercise may prevent additional pain from occurring. The ice may also be used for an additional fifteen minutes after the exercises.
At times a band worn below the knee cap tends to be helpful by relieving some of the pressure under the patella, and thereby relieve some of the pain.
The knee or knees should be examined by an orthopedic surgeon, who specializes in knee problems.
