Does injection of an extract of a patient's own blood into a knee joint reduce inflammation caused by osteoarthritis?

INTERVENTION: Before treatment, samples of synovial fluid are taken from the patient's affected knee and levels of 40 proteins are measured. This can be done if there is at least 1 ml of synovial fluid in the joint. The orthopedic surgeon extracts the fluid from the joint using a needle. All participants receive injections of autologous hyperacute serum produced using OrthoSera's device at 1 and 2 weeks after the synovial fluid sampling. 18 ml of blood (without anticoagulant) is taken from the right or left forearm vein of the patient using a butterfly needle set into the hypACT Inject Auto medical device. The SPRF fraction (hyperacute serum) is isolated using this device in a closed system by centrifugation. After centrifugation, the serum can be refrigerated and injected to the patient’s knee up to a week later or it can be injected immediately. It is transferred into a standard 5 ml syringe ready for injection into the affected knee joint. Pain, mobility and the patient's opinion of their knee problems are assessed at baseline, after treatment at weeks 1 and 2, and at 6 months follow‐up. Additional synovial fluid samples are taken at weeks 1 or 2 and at 6 months. CONDITION: Osteoarthritis ; Musculoskeletal Diseases PRIMARY OUTCOME: Markers of inflammation in synovial fluid measured using multiplex protein array (Luminex) technology at baseline, weeks 1 and 2, and month 6 SECONDARY OUTCOME: ; 1. Knee joint pain assessed using a Visual Analogue Scale (VAS) at baseline, week 1, week 2, and month 6; 2. Knee joint mobility assessed using the Lysholm scale at baseline, week 1, week 2, and month 6; 3. Patient's assessment of the impact of their knee impairment assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) at baseline, week 1, week 2, and month 6; ; INCLUSION CRITERIA: 1. Early or mild arthrosis of the knee joint that complies with Kellgren‐Lawrence Grade 2 or 3 on standing anteroposterior (AP) weight‐bearing X‐ray during the last 3 months before the enrolment. If the patient does not have a proper X‐ray from the last 3 months and indicates that he/she intends to participate in the study, a current X‐ray is taken and the diagnosis is made by an orthopaedic surgeon or a radiologist. 2. Aged 18 ‐ 55 years 3. Pain indicated by the patient is at least 40 on a 0 to 100 VAS scale during the last 3 months before the enrolment and the pain is related to the arthrosis 4. Clinical assessment that the pain is caused by the arthrosis 5. Inflammatory arthropathy is not included in the medical history or it is not suspected during the assessment 6. If the patient has a liver or kidney failure, then stable condition within the last