When I was young, my kneecaps used to slip out of place. After high school I seemed to have outgrown this problem. At age 35, my kneecaps sound like sand paper when I walk. I have pain if I climb a lot of stairs, kneel or watch a long movie. What can I do to prevent things from getting worse?

The symptoms that you have described are consistent with chondromalacia of the patella, or kneecap. Persons with chondromalacia have a softening and fraying of the patellar cartilage surface. The sandpaper sounds with stair-climbing discomfort and movie theater knee pain is classic for chondromalacia of the patella. Your condition is probably a byproduct of the patellar instability you described from your youth. A more subtle case of instability probably persists, causing the chondromalacia to progress. I would advise you to be evaluated for patellar instability and maltracking. Treatment would be physical therapy and a rehabilitation program to improve the tone and strength in your quadriceps muscle, or thigh muscles. Braces can assist with the patellar stability during exercise and sports. Only when nonoperative treatment is exhausted is surgery considered.