Dietary supplements for OA by and large either do not work, or the effect size is small. Combining them is usually non-additive in terms of outcome. You merely compound the cost and inconvenience.
Perhaps why no particular treatment seems to work particularly well in all OA patients is because OA is a diverse disease with diverse causes. This study identified 6 subtypes.
Perhaps tailoring treatment according to the subtype will yield better outcomes.
If you feel overwhelmed by the whole OA phenome and targeted therapy thing in the earlier post, this set of (Aussie?) guidelines harks back to simpler times when one size fits all.