How can I help prevent my knees from dislocating?

Patellar dislocate? Do you mean kneecap dislocations? The first line of treatment is physical therapy, to strengthen the muscles that regulate the tracking of the kneecap. You may use a kneecap stabilizing brace in conjunction with physical therapy. If extensive physical therapy does not resolve the issue, surgical options may need to be considered.
Exercises. You should seek medical evaluation to confirm the nature and severity of your problem. If your kneecap (patella) is dislocating, which is the most likely symptom you are describing, the initial treatment should be a guided physical therapy program to strengthen the stabilizing muscles of the thigh and leg. If this fails, your orthopedist can discuss other options including bracing and surgery.

Related Questions

What can I do about re-dislocating my knee? I've dislocated my knee for the third time in six years. What makes someone prone to this and what can I do to prevent it?

I. I would like to hear more details about what you are describing as a knee dislocation. True knee dislocations usually happen in major traumas where a significant force is required to disrupt the articular of the femur with the tibia (the knee joint). Far more common is a patellar subluxation. The patella is also called the kneecap. Usually this is felt as a clunking sensation in the knee, that "pops back in" when the knee is straightened. Sometimes the patella subluxes (slides out of its normal anatomic position) and then quickly returns to its normal position. This is perhaps more common in adolescents and young people. The first dislocation makes you prone to the next and those that follow. Beyond that, certain differences in limb alignment and rotation can predispose the patella to subluxate or dislocate. Prevention depends on what is causing it. After a first subluxation, the typical treatment is a short period of immobilization with the knee in extension to allow the retinacular structures to scar down and heal. With recurrent dislocations, there are a number of surgical procedures that could be used to address this problem. Physical therapy to strengthen the vmo (vastus medialis obliquus) may also be recommended by some, but usually for a first time dislocator.
Patella dislocation. Dislocation of the patella is different than "dislocating your knee". The patella pops out from direct trauma or a "knock knee" (valgus) alignment. Recurrent dislocations can be fixed with surgery to realign the knee.