Injections with autologous conditioned plasma do not lead to clinical relevant improvement up to 12 months after treatment

Abstract

Purpose: Treatment of osteoarthritis (OA) should aim at symptom reduction and delay or even prevent arthroplasty. Platelet-rich plasma (PRP) is an autologous product that consists of concentrated platelets. PRP was suggested to be beneficial in OA treatment due to high levels of (anti-inflammatory) cytokines and growth factors. Different compositions of PRP are currently used in daily practice worldwide. However, reported Results of injections with PRP in patients with OA vary between a very good to absent clinical response. The aim of this study is to assess clinical improvement after injections with PRP and to determine whether Kellgren & Lawrence (K&L) grade, age, gender, BMI, and history of a traumatic knee injury predict clinical outcome. Methods: A prospective cohort of 139 OA patients received three consecutive injections with ACP (Autologous Conditioned Plasma, Arthrex), with a one-week interval between the injections. ACP is a single-spin non-activated, leucocyte poor PRP with a 2-3 times platelet concentration compared to peripheral blood. The Knee Osteoarthritis Outcome Score (KOOS) was evaluated at baseline and 3, 6 and 12 months after treatment. Improvement compared to baseline was assessed for all domains and overall KOOS. Univariate linear regression was performed to determine the predictive value of age, sex, BMI, K&L grade and history of traumatic knee injury (cartilage defect, meniscus injury and anterior cruciate ligament rupture) on the clinical outcome. Generalized estimating equation (GEE) was used to explore the association between these factors and clinical outcome. Results: Baseline characteristics of the OA patients are shown in table 1. Compared to baseline, the overall KOOS improved with 6.4±13.7 after 3 months (n=132), 5.9±15.4 after 6 months (n=115) and 7.2±.16.6 after 12 months (n=70) (p<0.01, figure 1). The improvement was similar in all 5 domains of the KOOS (figure 2). Higher BMI and no history of traumatic injury were independent predictors of better outcome at 12 months. In our GEE model, K&L grade, age, gender, history of traumatic injury and BMI did not predict the clinical response. Conclusions: PRP treatment improved the KOOS at 3, 6, and 12 months, although this difference did not reach the minimally clinical relevant difference (8-10) described for the KOOS. The clinical improvement we found in this study is comparable to the improvement that was found in the placebo group of a trial investigating intra-articular injections for OA. Higher BMI and no history of traumatic injury were independent predictors of better outcome at 12 months, however the clinical relevance of these predictors remains debatable.