The aim of this prospective, randomized, controlled multi-centre study is to compare the effectiveness and safety of three and five injections of standard linear hyaluronic acid (HA) versus single HA injection in terms of pain intensity and functional status in patients with knee osteoarthritis.

Osteoarthritis (OA) is the most common form of chronic joint disease. A treatment option for patients diagnosed with knee osteoarthritis is intra-articular hyaluronic acid therapy. In this prospective, randomized controlled, single blind, interventional study, a total of 90 patients with stage 2-3 knee osteoarthritis according to the kellgren lawrence classification who meet the eligibility criteria will be enrolled in the study. Eligible participants will be randomly assigned to one of the three groups using computer-generated random numbers. In the first group, 2 ml linearly linked 20 mg 1.0% hyaluronic acid injection in 5 sessions, in the second group 2 ml linearly linked 32 mg 1.6% hyaluronic acid injection in 3 sessions and in the third group 2.4 ml linearly linked 48 mg 2.0% hyaluronic acid injection in a single sessions will be applied. Participants are going to evaluate before injection, at the 1-month follow-up, at the 3-month follow-up and 6-month follow-up using the visual analog scale (VAS) scores for pain during activity, at rest, and at night, with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) change in pain, stiffness and physical function score, the change in the Timed Up and Go Test (TUG) time and the change in the patient's daily activities with the numerical global patient assessment scale.

Inclusion Criteria:

• Unilateral or bilateral symptomatic knee pain for at least three months
• Presence of Kellgren-Lawrence stage 2-3 osteoarthritis on current anterior-posterior knee radiographs
• Functional ambulation scale stage 4-5
• Being able to attend injection and control examinations

Exclusion Criteria:

• Intra-articular knee injection within the last six months
• History of severe trauma to the knee within the past six months
• Concomitant severe meniscus or ligament injury, surgery applied to the knee area
• Presence of severe effusion, inflammatory joint disease, infection, hematological and oncological disease in the knee.
• Having a bleeding disorder and / or using warfarin
• Kellgren-Lawrence stage 1 or stage 4 osteoarthritis on current anterior-posterior knee radiographs
• Presence of cardiac or systemic disease that may affect exercise
• The presence of neurological disease and psychiatric disease such as Parkinson's disease, stroke history that may affect balance
• Body Mass Index ≥35 kg / m²
• Allergy to hyaluranic acid products