Intra-articular and extra-articular platelet-rich plasma injections for knee osteoarthritis: A 26-week, single-arm, pilot feasibility study

Aim: Platelet Rich Plasma (PRP) is an emerging therapy for knee osteoarthritis (KOA). Studies have evaluated the effectiveness of intra-articular PRP, which ignores extra-articular tissue dysfunction and may provide incomplete treatment of KOA. The study aimed to pilot test a leukocyte-rich (mononuclear cells) PRP injection protocol for primary KOA, which consisted of single intra-articular injection and extra-articular injections on the medial coronary and medial collateral ligaments. Methods: A prospective 26-week single-arm uncontrolled feasibility pilot study. Patients (N = 12) with primary KOA as defined by the American Rheumatology Association, with moderate to severe medial knee pain which failed conservative management, were recruited in a university primary care clinic and received a single session of PRP injection in week 1. The primary outcome was the feasibility of the protocol at 26 weeks as defined by rates of recruitment, compliance, retention, dropout, side effects or adverse events; and treatment satisfaction. Secondary outcomes included the Western Ontario McMaster University Osteoarthritis Index, the Intermittent and Constant Osteoarthritis Pain total and subscales, objective physical function tests and EuroQol-5D. Results: Twelve of 40 potential patients were recruited in 3 months period (recruitment rate 30%, x2 = 3.33, P = 0.068). All participants adhered to the protocol and completed the follow up assessment with no dropouts (dropout rate 0%, X2= 2.67, P = 0.103). Satisfaction was high; no related adverse events were reported. Most secondary outcomes showed statistically significant improvement. Conclusions: Concomitant intra-articular and extra-articular PRP injections were feasible and produced preliminary favourable outcomes.