Unusual lesions of the patella.

Degenerative or traumatic disorders of the patellofemoral articular cartilage are the usual cause of patellar pain. However, a wide variety of diseases may occasionally affect the bony center of the patella and closely mimic articular disease. Three cases, one each of giant cell tumor, metastatic carcinoma and monostotic Paget's disease are presented, with a review of the pertinent literature to illustrate the diversity of nonarticular disorders which should be considered in the differential diagnosis of patellar pain. Copyright 2013, SLACK Incorporated.