Table 2 Inclusion and exclusion criteria

1. MAT intra-articular injection in one or both knees;

2. Age between 18 and 80 years old;

3. Body Mass Index (B.M.I.) < 40;

4. Diagnosis of tibiofemoral osteoarthritis of the target knee/s at Kellgren-Lawrence (KL) grade ≥ 1 based on weight-bearing x-rays performed during the pre-treatment screening;

5. Knee symptoms that have lasted for more than six months;

6. Failure of at least one conservative treatment (activity modification and weight loss, physical therapy, or NSAID);

7. Failure of at least one intra-articular knee injection (corticosteroid, platelet-rich plasma [PRP], or hyaluronic acid [HA]).

1. intraarticular injection or orthopaedic surgical treatment of the lower limbs in the six months before the treatment;

2. valgus/varus deformity ≥ 10°;

3. any clinical condition that could have interfered with the outcome evaluation (i.e. severe hip or ankle OA, a disease of the spine, any severe illness of lower limbs other than knee OA);

4. any other concomitant surgical treatment during the intra-articular injection procedure (arthroscopy, meniscectomy, ligament reconstruction, etc.); any other intra-articular or tendon injection during the same procedure;

5. diagnosis of inflammatory or metabolic disease (rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, gout, etc.)