Patient case (clinical description): A 47-year-old woman comes to the office complaining of pain in the calf and knee when she bends down. The pain limits her activity. Her medical history is significant for osteoarthritis, for which she uses nonsteroidal anti-inflammatory drugs (NSAIDs) for the past two years. She is living with her husband and has 3 children. She doesn't smoke but drinks alcohol occasionally. Her vital signs are normal. On physical examination, there is a small effusion in the right knee. The effusion grew a little larger and she developed a tender swelling in the popliteal fossa and calf. Both the pain and swelling worsened as she bent and straightened her knee.

Patient's own account: I'm a 47-year-old woman, married with 3 kids. I don't smoke and I drink occasionally. I went to the doctor because of pain in my calf and knee when I was bending down. This has been limiting my daily activities. I have been diagnosed with osteoarthritis for which I have taken anti-inflammatory drugs for the past 2 years. The doctor saw a small fluid buildup in my right knee. This buildup became a bit bigger and I have a swollen calf. The pain is worse when I bend and straighten my knee.

Clinical trial: Medical Chitosan or Sodium Hyaluronate for Knee Osteoarthritis (CHOOSE)

Eligibility criteria:
Inclusion Criteria:

          1. Males or females at the age of 40-75 years old

          2. Conforming to the diagnosis standard of the American College of Rheumatology in 2009：
             knee pain and osteophyte determined with X-ray, and at least one of the following
             items：

               -  above 50 years old

               -  morning stiffness less than 30 minutes

               -  knee joint with fricative when moving

          3. The studying knee has score of 40-90 mm on a 100 mm measured VAS and the other side
             was less than 40mm when walking on flat ground.

          4. The studying knee has score of 1, 2 or 3 determined by radiological Kellgren-Lawrence
             grading scale.

          5. Patients who have treatment requirements and can obey the therapeutic schedule

          6. Body mass index(BMI) ≤35kg/m2。

          7. Able to follow the clinical observation and follow up.

          8. The subjects are able to understand and sign the informed consent after fully
             understand this study, the disease, investigational drugs, the therapeutic schedule
             and the potential risks.

        Exclusion Criteria:

          1. Positive signs of swelling or floating patella test，and there are obvious effusion of
             knee joint in clinical.

          2. Other inflammatory pain diseases of knee joint, such as rheumatism/ rheumatoid
             arthritis, psoriatic arthritis, gout, hemophilic arthritis, etc.

          3. Pain diseases of knee joint, except for osteoarthritis, such as intra-articular tumor,
             villonodular synovitis, joint trauma, etc.

          4. Pregnant or lactating females.

          5. Participants who suffer from serious cardiovascular disease (Sudden cerebral
             infarction with sequela or myocardial infarction within recent 6 months), hepatic
             disease, kidney disease；Participants whose ALT and AST are twice or more than twice
             than that of the upper limit of normal value；Participants whose serum creatinine
             exceed the upper limit of normal value；Participants who suffer from dysfunction of
             blood coagulation (thrombocytopenia, bleeder disease, etc.)

          6. Participants who have systemic infection or infectious disease.

          7. Participants who suffer from serious skin defect or ulcer around the studying knee
             joint.

          8. Participants who suffer from typical varus or valgus deformities or lack of articular
             cavity.

          9. Participants with diabetes and have to inject insulin or who are not good enough to
             control the blood glucose (FBG ( fasting blood-glucose) ≥10mmol/L.)

         10. Participants who suffer from cancer (within 5 years) or Alzheimer's disease.

         11. Participants with score 0 or 4 of the studying knee joint evaluated by radiological
             Kellgren-Lawrence grading scale.

         12. Participants who have hormone drugs within 2 weeks or analgesic drugs within 1 week
             before this trial or take part in other clinical trials.

         13. Participants whose studying knee receives articular cavity therapy within 3 months,
             containing intra articular administration, articular irrigation and arthroscopic
             surgery

         14. Participants with an allergy to the experimental drugs.

         15. Participants who are not suitable for this trial judged by the researchers.
No condition on gender to be admitted to the trial.
No healthy subjects accepted to join the trial.
Subject must be at least 40 Years old.
Subject must be at most 75 Years

Eligibility (NLI label): Entailment