The aim of this study was to assess a novel approach to treating severe knee osteoarthritis by targeting synovialmembrane, superficial articular cartilage, synovial fluid, and subchondral bone by combining intra-articular injections and intraosseous infiltrations of platelet rich plasma.This study explored a new strategy consisting of intraosseous infiltrations of platelet rich plasma into the subchondral bone in combination with the conventional intra-articular injection in order to tackle several knee joint tissues simultaneously.

Inclusion Criteria:

• Patients of both sexes aged 40 to 77 years.
• Predominant internal tibiofemoral knee osteoarthritis.
• Joint pain above 2.5 VAS points.
• Radiographic severity degrees 3 and 4 according to Ahlbäck scale.
• Values of body mass index between 20 and 33.
• Possibility for observation during the follow-up period.

Exclusion Criteria:

• Bilateral knee osteoarthritis which requires infiltration in both knees.
• Values of body mass index > 33.
• Polyarticular disease diagnosed.
• Severe mechanical deformity (diaphyseal varus of 4∘ and valgus of 16∘).
• Arthroscopy in the last year prior to treatment.
• Intra-articular infiltration of hyaluronic acid in the past 6 months.
• Systemic autoimmune rheumatic disease (connective tissue diseases and systemic necrotizing vasculitis).
• Poorly controlled diabetes mellitus (glycosylated hemoglobin above 9%).
• Blood disorders (thrombopathy, thrombocytopenia, and anemia with Hb < 9).
• Undergoing immunosuppressive therapy and/or warfarin.
• Treatment with corticosteroids during the 6 months prior to inclusion in the study.