AB0992 Prognostic factors related to clinical response in 197 patients with knee osteoarthritis treated by platelet rich plasma (PRP)

Abstract

BackgroundThe European League Against Rheumatism (EULAR) [1] and the Osteoarthritis Research Society International (OARSI) [2] recommend a combination of non-pharmacological and pharmacological treatment in the management of knee osteoarthritis. New therapies have emerged such as Platelet Rich Plasma (PRP) injections. Many studies have shown the effectiveness of this treatment, and even its superiority over Hyaluronic Acid.ObjectivesThe aim of this study was to determine the prognostic factors related to clinical response to PRP injections in knee osteoarthritis, in order to better select candidates for this therapy.MethodsThis was a single-center, prospective observational study including patients treated by PRP injections for knee osteoarthritis, from a university hospital. The PRP was leukocyte-poor, obtained by an ARTHREX kit, and was injected twice, at one-month intervals. They were assessed at 4 months (M4) and 7 months (M7) after the first injection. Pains on a Visual Analog Scale (VAS) and function with Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Knee injury and Osteoarthritis Outcome Score (KOOS) – Physical Function Shortform (KOOS-PS) were collected. Patients were then classified as responders if they met the OMERACT-OARSI criteria at M7. Univariate and multivariate analysis was performed to compare the two groups.ResultsAmong 197 patients, 210 knees were treated. The mean age was 59.8±10.8 years, Body mass index (BMI) was 31.0±6.5. Patellofemoral osteoarthritis was found in 34.3% of the patients, the distribution according to Kellgren and Lawrence stages I, II, III, IV was 11.8%, 33.5%, 40.4% and 14.3% respectively. A majority of patients had failed viscosupplementation (62.4%). At 7 months, 43.8% were classified as responders. Total WOMAC was 49.4±16.1 at M0, 43.6±17.9 at M1, 31.1±19.0 at M4 and 31.9±19.8 at M7, with significant improvement at M4 and M7 versus baseline (p<0.0001). The VAS was 58.5±19.7, 51.6±21.7, 43.7±23.2 and 43.5±23.5 at M0, M1, M4 and M7 respectively (p<0.0001 at all 3 times versus baseline). Regarding treatment satisfaction, 70% of patients considered the treatment effective or very effective at M7. Physical therapy and a heel-buttock distance greater than 35 centimeters were the two criteria associated with a poorer response at M7 on multivariate analysis. The pain VAS at M7 appeared to be lower in patients whose osteoarthritis had been evolving for less than 24 months. Tolerance was good. There was an increase in joint effusions between M0 and M1 (17% vs. 41%, p<0.0001), but no increase in pain.ConclusionPRP treatment in knee osteoarthrisis appeared to be effective and well tolerated, and this response was not associated with the radiographic stage or the type of knee osteoarthritis. In accordance with the recommendations of a group of French experts, this treatment should be proposed in case of failure of drug and rehabilitation treatment, at the same level as hyaluronic acid injections.