 Primary efficacy analysis: The primary outcome will be the reduction in WOMAC total score from baseline to week 16. The week 16 means for the four treatment groups will be compared using an analysis of covariance taking account of baseline assessments and any demographic differences, age, gender, etc, which are found to be significant. Multiple comparison tests will be used to examine specific differences of initially specified interest, such as the two highest doses of Devils Claw versus placebo. 