Knee osteoarthritis (OA) is common and prevalence is increasing with ageing populations and rising levels of obesity. Thus, it is imperative to find effective treatment options for early management of people with knee OA, thereby decreasing pain and disability. Oral anti-inflammatory medication and physiotherapy are proven treatments for people with knee OA, but the effect of combining them is unknown. We will evaluate clinical and cost-effectiveness of adding anti-inflammatories to best practice physiotherapy, compared with physiotherapy alone in a randomised controlled trial (RCT). Prior to a fully powered RCT, we propose a feasibility trial to establish the acceptability and safety of the intervention and trial procedures, test participant recruitment and screening, and accurately estimate the cost of conducting the full RCT. Study findings will inform physiotherapists, pharmacists, doctors, and patients about the best way to use physiotherapy and anti-inflammatories for long-term management of knee OA.