This is a randomized, double-blind, active-controlled, multi-center, phase 3 study to evaluate the safety and efficacy of intraarticular hyaluronic acid(YYD302) for osteoarthritis of the knee after 12 weeks of treatment and retreatment

First Injection: A multicenter, active-controlled, randomized, evaluator and subject bllinded, parallel, phase 3 study Re-Injection: A multicenter, active-controlled, randomized, parallel

Inclusion Criteria:

[Visit 1, 2 Inclusion Criteria]

1. Males or Females 40 years and older
2. According to the clinical diagnosis standard of the American College of Rheumatology (ACR), someone, diagnosed as a single/both sides of osteoarthritis, who corresponds to over 3 conditions of followings.

1) Over 50 years of age 2) Less than 30 minutes of morning stiffness 3) Crepitus on active motion 4) 4 bony tenderness 5) Bony enlargement 6) Nopalpable warmth of synvium 3. Within 6 months from screening visit, someone who diagnosed with Kellgren & Lawrence Grade I~III by the radioactive examination.

4. By the Weight-bearing pain(100mm-VAS) examination, someone who has a outcome of the single or both sides of the osteoarthritis is over 40mm 5. Patient (No-responder) who has experienced steady pain in spite of dosing NSAIDs or other pain-killers in the past.

6. Patient who can walk by themselves without helper like cane or walker etc. (If the patient who has used helper routinely from previous 6 months, evaluating the patient including the helper is possible. In this case, patient needs to use same helper continuously by end of the clinical trial test.) 7. Patient who agrees to participate in this clinical trial by themselves.

[Visit 6, 7 Inclusion criteria] 1. According to the clinical diagnosis standard of the American College of Rheumatology (ACR), someone, diagnosed as a single/both sides of osteoarthritis, who corresponds to over 3 conditions of followings.

1. Over 50 years of age
2. Less than 30 minutes of morning stiffness
3. Crepitus on active motion
4. 4 bony tenderness
5. Bony enlargement
6. Nopalpable warmth of synvium 2. At Re-screening visit, someone who diagnosed with Kellgren & Lawrence Grade I~III by the radioactive examination.

3. Patient who can walk by themselves without helper like cane or walker etc. (If the patient who has used helper routinely from previous 6 months, evaluating the patient including the helper is possible. In this case, patient needs to use same helper continuously by end of the clinical trial test.) 4. Patient who are confirmed for Responder by efficacy at visit 5.

Exclusion Criteria:

1. Someone who has BMI≥32kg/m² at the screening visit.
2. Patient who has an experience dosing psychoactive drug, narcotic analgesic which can have an effect on pain sense over 3 months habitually.
3. Patient who has been administrated gastrointestinal drug(for example H₂-blockers, misoprostol or proton pump inhibitors) regularly, who can't stop injecting for clinical study period.
4. Patient has attended abnormal values from screening test(2 times excess at upper limit of the normal values at ALT, AST, BUN, Serum Creatinine).
5. Patient who has rheumarthritis or other inflammatory metabolic arthritis.
6. Patients having serious gastrointestinal, liver, renal, heart disease.
7. When the inflammatory disease is occurred on joint area to patient like septic arthritis.
8. Patients having skin ailment at the injecting site of the joint region.
9. Patients having secondary osteoarthritis according to the Ochronosis, Hemochromatosis or systemic disease.
10. Patients who have severe pain like Sudek's atrophy, Paget's disease, Spinal disc herniation.
11. Poly-articular patients who have suffered seriously by osteoarthritis at other parts affect judge of the knee joint pain.
12. Patients who diagnosed clear interval disappearance at the knee joint by X-ray.
13. Patients who were administrated below drugs before baseline visit. 1) Patients who were injected HA at the target knee joint or other parts of knee joint in recent 9 months.

2) Patients who were injected steroids into the intra-articular knee joint in recent 3 months 3) Patients who were administrated steroids systemically by the oral medication (But, except inhalation) 4) Patients who were administerated Osteoarthritis nutrition such as glucosamine/chondroichin sulfate or physical therapy or herbal remedy(acupuncture, yellowish swelling, moxa cautery) for the purpose of pain relief in recent 2 weeks 5) Patients who have administerated steroid/No-steriod NSAIDs or other pain relief drugs (patch or other external medicine) in recents 2 weeks except Acetaminophen or below 300mg/day of Asprin 14. Patients who have joint effusion trouble were judged as a positive by tests like Patella tap test.

15. Patients who have target knee joint gotten surgical operation history including Arthroscopy within past one year (In case of having other side of knee joint or hip joint gotten surgical operation history, excepting the patients if there is possibility which can influence the target knee joint's appraisal.

16. Patients who have an operation history about target knee joint. 17. Patients who do the height weight aerobic exercise or anaerobic exercise. 18. Patients who need to be administrated anticoagulant agent together(But, except 300mg daily dose aspirin) 19. Patients who have hypersensitivity history about Investigational Product.

20. In the midst of women in their childbearing years, patients who disagree to do * contraception by medically permitted method for 12 weeks from administrating investigational product.

• The contraception by medically permitted method: Condom, In case of using injection or insertion, In case of installing a intrauterine contraception device etc.

  21. Pregnant and lactating women 22. Patients who were injected other investigational product over a time within 30 days before participated in this clinical trail.

  23. Besides that, the patients who have difficulty to be participated in this clinical trial continuously by Principle Investigator (PI)'s decision.

• Exclusion criteria for Re-injection is except for 13-1) Re-injection date is followed by visit 7.