The purpose of this study is to evaluate the efficacy of intra-articular injections of combined hyaluronic acid and platelet-rich plasma in knee degenerative joint disease in improving joint function and reducing pain.

Inclusion criteria:

• Knee pain for 4 months;
• Knee degenerative sign evaluated with X-ray with a Kellgren-Lawrence grade inferior to 3;
• Patients able to understand the study conditions and willing to participate for its entire duration;
• Patients who signed written informed consent.

Exclusion criteria:

• Severe knee osteoarthritis of grade 4;
• Diabetes mellitus;
• Rheumatoid arthritis;
• Ongoing malignancies;
• Certified allergic reactions towards the administered drugs ;
• Malalignment of mechanical axis of the lower limb (varus > 10 °, valgus > 10 °);
• Coagulopathies;
• Severe cardiovascular diseases;
• Ongoing infections;
• Immunodepression;
• Anticoagulants or anti-platelet agents;
• Haemoglobin < 11 g/dl;
• Platelet count < 150,000/mm^3
• Drug addiction;
• Alcoholism;
• Psychiatric disease;
• Pregnancy or breastfeeding.