Acute calcific quadriceps tendinitis.

Acute calcific quadriceps tendinitis can be the cause of acute periarthritis of the knee. Physical examination can detect cellulitis and a tender tendon sheath. Lateral roentgenograms of soft tissues show thickening of the tendon and sometimes small flecks of amorphous calcification within the body of the tendon near the attachment. Although hyperostosis of the patella near the tendon attachment is often present, it is well defined ossification and not associated with the acute symptoms. The amorphous calcium deposits quickly disappear during the acute tendinitis and are not detected on follow-up radiologic examination.