Table 1.

Inclusion and exclusion criteria.

Inclusion Criteria

-Diagnosis of OA changes stage II-III Kellgren–Lawrence by radiography (postural bilateral lower limb, weight-bearing standard knee anterior-posterior view in full extension, lateral view in 30 of flexion). -No prior PRP injection in the knee. -No prior surgical procedure in participating knee. -Unilateral Visual Analog Scale (VAS) pain score 4–9 for >6 months. -Age between 40 and 75 years. -BMI < 40 kg/m2 -Ability to provide informed consent. -Conservative treatment in the form of exercise, weight reduction, and physical therapy for at least 6 months, without improving the function and reducing pain. -The patient will refrain from treating the knee joints by intra-articular injection, surgery, and physical therapy for the duration of the study. -The patient refrains from taking pain relievers, including non-steroidal anti-inflammatory drugs (NSAIDs), for the duration of the study. Only paracetamol preparations are allowed on an ad hoc basis with a ban on taking them 24 h before the visit.

Exclusion Criteria

-Type II diabetes. -Fibromyalgia. -Anemia. -Coagulation disorders or taking anticoagulants. -Pregnancy or lactation. -Allergic to a steroid drug or hyaluronic acid. -Large (more than 10 mL of aspirated synovial fluid) effusion in the knee joint or abnormal synovial fluid appearance. -A history of purulent inflammation of the knee. -Rheumatic diseases and systemic diseases of connective tissue. -Active neoplastic disease. -The patient is undergoing oral steroid therapy, antibiotic therapy or biological treatment. -The patient received an intra-articular injection into the examined joint in less than a year before the screening visit. -The patient had previous operations, fractures, ligaments or meniscus injuries in the area of the examined lower limb. -The patient has a Baker’s cyst. -The patient is addicted to nicotine, alcohol, or drugs. -The patient had an injury to the examined knee joint within one month of the screening visit. -The patient has a significant deformation of the examined knee joint. -There is a valgus or varus greater than 10° in any of the knees. -The range of motion of the knee joint is less than 100°. -Major axial deviation (varus > 5, valgus > 5). -Any concomitant symptomatic knee disorder (i.e., ligamentous or meniscal injury). -Hematologic disease. -Active infection. -Recent intra-articular injection of corticosteroid or HA in past 6 months.