A dislocated knee cap is when the triangle-shaped bone covering the knee (patella) moves or slides out of place. The problem usually occurs toward the outside of the leg. See dislocation.

Dislocated knee caps most often occur in women. It is usually a result of sudden direction changes while running. This puts the knee under stress.

Dislocation may also occur as a direct result of injury. When it is dislocated, the knee cap may slip sideways and around to the outside of the knee.

The first few times this occurs, you will feel pain and be unable to walk. However, if dislocations continue to occur and are untreated, you may feel less pain and have less immediate disability. This is not a reason to avoid treatment. Knee cap dislocation damages your knee joint.

• Knee cap (patella) is displaced to the outside of the knee
• Knee swelling
• Knee pain and tenderness
• "Sloppy" knee cap; that is, able to move the knee cap excessively from right to left (hypermobile patella)