The kneecap (patella) is normally positioned over the front of the knee joint at the base of the thighbone (femur). A kneecap can be dislocated, or moved out of its normal position, when:
- The kneecap is out of place (patellar tracking disorder) and force is applied, causing dislocation.
- The foot is firmly planted pointing outward, and the knee is bent with the thigh turned inward. This kind of injury is common during many sports activities.
- The inner edge of the kneecap is hit, pushing it toward the outer side of the leg.
Symptoms of a dislocated kneecap may include:
- Severe pain.
- A misshapen knee that looks like a bone is out of position.
- A popping sensation, followed by a feeling that something is out of place.
- Inability to bend or straighten the knee.
- Knee swelling.
- Cool, pale skin or numbness and tingling in or below the affected knee.
A dislocation can cause other problems even if the bone pops back into place.
- If the dislocation was due to a preexisting malalignment, the knee may dislocate again.
- Ligaments, tendons, muscles, and cartilage in or around the joint may stretch or tear.
- A piece of bone may break off somewhere in the knee joint.
|Primary Medical Reviewer||William H. Blahd, Jr., MD, FACEP - Emergency Medicine|
|Specialist Medical Reviewer||Patrick J. McMahon, MD - Orthopedic Surgery|
|Last Revised||January 9, 2012|
Last Revised: January 9, 2012
Author: Healthwise Staff
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