Three intra-articular injections in total and autologous adipose-derived mesenchymal stem cells (AMSCs) suspended in 3 ml autologous platelet rich plasma (PRP) for each injection. Time-points for intervention: 1) initial injection; 2) 3 months following initial injection; 3) 6 months following initial injection.

Three intra-articular injections in total and 3 ml autologous platelet rich plasma (PRP) for each injection. Time-points for intervention: 1) initial injection; 2) 3 months following initial injection; 3) 6 months following initial injection.

150 mL subcutaneous abdominal adipose tissue will be harvested via liposuction . AMSCs will be isolated and cultured from adipose tissue. Before injection, 30 mL of blood will be collected from each patient to produce 3ml PRP by cenrifugation.Cultured AMSCs will be collected and suspended by 3ml autologous PRP.

Evaluation the physical function change measured by the Western Ontario and McMaster Universities Arthritis Index (WOMAC). The WOMAC consists of three subscales: pain (five questions), stiffness (two questions), and physical function (17 questions). The subscale scores can vary, with pain ranging from 0 to 20 points; stiffness, 0 to 8 points; and physical function, 0 to 68 points. Higher scores represent worse pain, stiffness, and functional limitations.

Evaluation the changing of pain density measured by Visual Analogue Scale. Draw a 10 cm horizontal line on the paper. One end of the line is 0, indicating no pain; the other end is 10, indicating severe pain; and the middle part indicates varying degrees of pain. The patient selects a point from the horizontal line and the length from 0 to this point is the Visual Analogue Scale score.

Evaluation of cartilage repair under MRI. Recht criterion was used for grading articular cartilage injury of knee joint, including 0-IV grade, in which: 0 grade, normal articular cartilage, no obvious abnormal signal was found; 1 grade, the layered structure of cartilage disappeared, and there were focal low signal areas, but the surface was smooth; 2 grade, the surface of cartilage was irregular, the depth of cartilage injury was less than 50% cartilage thickness; 3 grade, the surface of cartilage was heavy. The degree of injury is irregular, the depth of injury is more than 50% of the thickness of cartilage or through the whole layer, but the surface of cartilage is not completely exfoliated; Grade IV, full-thickness cartilage defect, articular cartilage injury deep to the cortex, subchondral bone exposed.