Final answer:
The condition where the knee cap pops out of place is called patellar dislocation, not to be confused with Runner's Knee which is an overuse injury causing pain but not dislocation.
Step-by-step explanation:
What do you call the condition when the knee cap pops out of place?
The condition when the knee cap pops out of place is known as a patellar dislocation. This is different from Runner's Knee or patellofemoral syndrome, which is an overuse injury resulting in pain at the front of the knee but doesn't involve displacement of the kneecap. Patellar dislocation occurs when the bones of the knee are subjected to a force that pushes the patella out of its normal alignment with the femur, often resulting from a direct blow to the knee or a sudden twist. Symptoms can include visible displacement of the knee cap, pain, swelling, and difficulty in knee movement.
Treatment for a dislocated patella typically involves initially reducing the dislocation (putting the knee cap back in place), rest, and eventually rehabilitation exercises to strengthen the muscles around the knee, particularly the quadriceps femoris muscle, to prevent recurrence. Severe or repeated dislocations may require surgery.