To determine the potential efficacy and feasibility of photobiomodulation therapy (PBMT) before and after knee arthroplasty (KA) surgery. Total knee replacements (total knee arthroplasty, TKA) are one of the most common and successful surgical interventions for osteoarthritis. Up to 20,000 knee replacement arthroplasties are performed in Australia annually. Although TKA aims to restore knee alignment and relieve pain in the long term, the initial post-operative period is difficult and rehabilitation is often hindered by persistent pain and swelling. A promising therapeutic approach, PBMT using a novel self-adhesive light patch system, may be feasible for reducing post-operative pain and swelling and aiding recovery. This is an interventional clinical feasibility study protocol. Patients from a surgical waitlist will be invited to take part. PBMT will be applied for 30 min daily for 7 days pre-operatively using a novel light patch system (CareWear) with both 450 nm (6.75 mW/cm) and 640 nm (2.25 mW/cm) microdiodes. Post-operative treatment will utilize the same device second daily for 1 week after removal of compression bandages. Outcomes will be evaluated at seven time points: baseline at week 1 pre-operatively, 1 day before surgery, day 4 after surgery, weekly for a further 2 weeks, and fortnightly until 6 weeks post-hospital discharge. Outcome measures include the following: Numeric Pain Rating Scale, stair climb test, 30-sec chair stand test, timed up and go test, 40-m fast-paced walk test, modified Iowa Level of Assistance Scale, muscle strength, knee range of motion, Knee Injury and Osteoarthritis Outcome Score, and Lower Limb Functional Index. This study will provide an assessment of feasibility of using PBMT applied using a novel light patch system for management of pain symptoms and swelling, and aiding recovery of patients undergoing TKA. The results of this feasibility study will contribute to planning of the design and methods of a large clinical trial.