Common causes of swelling on the side of the knee are iliotibial band syndrome, patellar dislocation, and patellar tendinitis, according to WebMD. Patellar dislocation and patellar tendinitis both affect the kneecap, while Iliotibal band syndrome affects the tissue from the hip to the outer knee.
Iliotibial band syndrome is caused by overusing the tissues on the outer thigh and knee. It causes pain and inflammation on the side of the knee, explains MedicineNet. If symptoms are not treated, the inflammation causes scarring in a part of the knee called the bursa, decreases knee flexibility, and increases pain. Doctors recommend resting and icing the side of the knee. Physical therapy can help with inflammation and movement of the knee.
Patellar dislocation, also known as a dislocated kneecap, occurs when the kneecap moves out of the normal location. It looks like the bone is out of position and can cause pain and swelling, according to WebMD. Patellar tendinitis is an injury of the tendon that connects the kneecap to the shin. It most often affects athletes who do a lot of jumping. Symptoms include pain and swelling, reports Mayo Clinic. Physical therapy can help stretch and strengthen the muscles in the knee.