The purpose of the study is to compare the efficacy and safety of flavocoxid (Limbrel) with Naproxen and placebo in OA of the knee.

To compare the efficacy, safety, quality of life and economic impact of flavocoxid vs naproxen.

Inclusion Criteria:Major inclusión criteria:

1. Adults of either gender, ages 35-85, in general good health
2. Diagnosed with OA of the knee, K-L Grade 2-3
3. History of positive response to NSAID's or COX-2 inhibitors
4. Able and willing to discontinue other medicinal OA therapies for length of the study (subjects may continue low dose aspirin for cardioprotection)
5. Females of child bearing potential must use acceptable method of birth control

Major exclusion criteria:

1. Unwilling or unable to read and sign informed consent document
2. Pregnant and nursing women
3. History of severe cardiovascular disease including, but not limited to chronic angina, congestive heart failure, uncontrolled hypertension, acute myocardial infarction within past year
4. K-L grade 1 or 4 OA of the target knee
5. chronic bleeding disorder or present use of anticoagulants
6. History of upper G-I bleed in the past 5 years
7. Significant renal disease including nephrotic syndrome, proteinuria >1 gm/24 hrs or serum Creatinine >2.0
8. Any arthritic disease that is or has the potential to affect the knees during the course of the study
9. Any other condition that might confound evaluation of the target joint including, but not limited to, bursitis, tendonitis or internal derangement in or about the knee, gait disturbances (e.g. mechanical, neurological conditions or disorders of the back), fibromyalgia, polyneuropathies, etc.