Both glucocorticoid and sinomenine are widely used in the routine clinical treatment of osteoarthritis, but there is still a lack of high level of clinical evidence for the direct comparison of efficacy between the two drugs. This trial aims to evaluate whether intraarticular injection of sinomenine was noninferior to intraarticular injection of glucocorticoid for symptom relief in patients with early knee arthritis, and whether intraarticular injection of sinomenine was superior to intraarticular injection of glucocorticoid for changes in tibial cartilage volume (measured by mean thickness) from baseline compared with intraarticular injection of glucocorticoid. 326 people will participate in the study at 3 different research/medical institutions, with centres competing for inclusion. This trial was designed by random blind method. This trial will last for 2 years and participants will receive 6 injections every 4 months.

Inclusion Criteria:

1. Age > 40 and <70.
2. Bilateral knee pain lasting for more than 6 months and most of the last month;
3. X-rays showed that Kellgren and Lawrence had grade 2 or 3 knee osteoarthritis.

Exclusion Criteria:

1. Kellgren and Lawrence Level 1 or 4.
2. Radiographs showed that the reduction of the lateral joint space was greater than or equal to the medial joint space.
3. The affected knee had been injected with glucocorticoid or hyaluronic acid within the past 6 months.
4. Have had knee surgery or plan to have joint surgery on the affected knee.
5. Other medical conditions such as: systemic or inflammatory joint diseases (rheumatoid arthritis), history of crystalline or neurological joints, other muscular, joint or nervous system diseases affecting lower limb function.
6. Have a needle phobia.
7. Immunosuppression or acute infection is present.
8. Patients are allergic to the drugs involved in the study.
9. Have or have had cancer or tumours.
10. Have a hemorrhagic disease or are receiving anticoagulant or antiplatelet therapy.
11. History of hyperlipidemia, or plasma total cholesterol ≥6.2mmol/L and triglycerides >2.3mmol/L
12. Have any other medical conditions that do not participate in the study, including contraindications to MRI, such as pacemakers.
13. Pregnancy.
14. Body mass Index (BMI) > 40 kg/m2.
15. Unable to attend all study appointments within 24 months;
16. Inability to understand written and spoken Chinese.
17. Any history of mental and psychological illness.