Intra-articular injections of platelet-rich plasma (PRP) and other novel blood-derived products developed specifically for osteoarthritis (OA) can provide pain relief and potential benefits in disease progression. Meta-analyses show the clinical superiority of PRP compared with other intra-articular injections, but results are modest and the effect sizes are small. PRP injections in knee OA are performed indiscriminately, but the clinical response varies enormously between patients because of an array of mixed OA phenotypes. Subgroup analyses are scarce; some studies stratify patients according to radiographic severity and found better results in early OA, without consensus for more advanced stages of the condition. Parallel identification of soluble and imaging biomarkers is essential to personalise and leverage PRP therapies. The inflammatory phenotype is most interesting from the PRP perspective because PRPs modulate inflammation by releasing a large pool of chemokines and cytokines, which interact with synovial fibroblasts and macrophages; in addition, they can modulate the innate immune response. No soluble biomarkers have been discovered that have implications for OA research and PRP interventions. Clinical examination of patients based on their inflammatory phenotype and imaging identification of pain sources and structural alterations could help discern who will respond to PRP. Synovial inflammation and bone marrow lesions are sources of pain, and intra-articular injections of PRP combined with subchondral bone injection can enhance clinical outcomes. Further refining ultrasound phenotypes may aid in personalising PRP therapies. Intra-articular delivery combined with injections in altered ligamentous structures, medial and coronal ligaments or premeniscal pes anserinus showed positive clinical outcomes. Although the evidence supporting these approaches are weak, they merit further consideration to refine PRP protocols and target the right OA phenotypes.

Objectives To determine the efficacy of platelet-rich plasma (PRP) compared to lidocaine as a tenotomy adjuvant for people with elbow tendinopathy. Methods Our study was a parallel-group, double-blind, randomized trial involving 71 patients with recalcitrant elbow tendinopathy who received two sessions of ultrasound-guided tenotomy with either PRP or lidocaine in a tertiary public hospital. The primary end point was the percentage of patients with an improvement exceeding 25% reduction in disability (Spanish version of the Disabilities of the Arm, Shoulder and Hand questionnaires–DASH-E) at 6 and 12 months; the secondary outcome was the percentage of patients exceeding 25% reduction in pain (VAS-P). Results There was no evidence of significant differences in the proportion of patients who experienced clinically relevant improvements. After 6 months, 18 patients (78.59%) in the lidocaine group and 19 patients (73.08%) in the PRP group showed improved function above 25% (unadjusted odds ratio, 0.90; 95% confidence interval [CI], 0.90 (0.17 to 4.60)); 21 patients (72.21%) in the lidocaine group versus 22 patients (84.62%) in the PRP group achieved more than 25% pain reduction (unadjusted odds ratio, 0.48; 95% CI, 0.10 to 2.37). After 12 months, 17 patients (70.83%) in the lidocaine group versus 19 patients (76%) in the PRP group had improved function (unadjusted odds ratio, 0.71; 95% CI, 0.13 to 3.84), and 19 patients (76%) in the lidocaine group versus 20 patients (90.91%) in the PRP group had improved pain above 25% (unadjusted odds ratio, 0.35; 95% CI, 0.06 to 2.51). Hypercholesterolemia and baseline vascularization influenced outcomes. There were no differences between groups in the adjusted odds ratios. Conclusion PRP results in similar improvements to those obtained with lidocaine. Selecting patients according to their pretreatment status can improve treatment efficacy. Trial registration NCT01945528 , EudraCT 2013-000478-32. Registered 18 August 2013, enrolment of the first participant 10 March 2014

BackgroundTendinopathy is a difficult problem to manage and can result in significant patient morbidity. Currently, the clinical use of platelet-rich plasma (PRP) in painful tendons is widespread but its efficacy remains controversial.Methods/DesignThis study is a single-center, randomized double-blind controlled trial. Eighty patients will be allocated to have ultrasound (US)-guided needling combined with a leukocyte-depleted (that is, pure) PRP or lidocaine each alternate week for a total of two interventions. Outcome data will be collected before intervention, and at 6 weeks, 3, 6, and 12 months after intervention. Main outcome measure: Changes in pain and activity levels, as assessed by Disabilities of the Arm, Shoulder and Hand (DASH-E, Spanish version) score, at 6 months. We will compare the percentage of patients in each group that achieve a successful treatment defined as a reduction of at least 25% in the DASH-E score. Secondary outcome measures include changes in DASH-E at 3 and 12 months, changes in pain as assessed by the visual analogue scale (VAS) at the 6-week, 3-, 6-, and 12-month follow-up, changes in sonographic features and neovascularity, and percentage of patients in each group with adverse reactions at 3, 6, and 12 months.DiscussionThe results of this study will provide insights into the effect of pure PRP in tendon and may contribute to identifying the best protocol for PRP application in tendinopathies.Trial registrationClinicalTrials.gov: NCT01945528.