Recently there has been a growing interest in the role of subchondral bone in knee arthritis, both in its etiology and evolution and in its clinical significance. It has now been widely demonstrated that changes in the subchondral bone can develop both as a cause and as a consequence of joint degeneration and it is now accepted in the scientific community that the presence of these changes is of clinical importance, causing pain and an inflammatory state that can contribute to the evolution of arthrosis arthropathy. Recently the use of mesenchymal cells obtained from the bone marrow has been proposed for the treatment of gonarthrosis by intra-articular injections. Even more recently, treatments have been studied and proposed for the treatment of the bone-cartilage interface in knees affected by osteoarthrosis, using autologous bone marrow concentrate, with promising results.

Osteoarthritis (OA) is a chronic degenerative and disabling disease of joint joints, in which metabolic impairment between the synthesis and degradation of cartilage and subchondral bone, involves progressive destruction of joint tissue accompanied by chronic pain and synovial inflammation. Currently, available therapies are mostly palliative and designed to mask symptoms. The study proposed here has been constructed on the basis of the scientific evidence reported in the literature regarding the etiology and the treatment of OA. As recently demonstrated, the use of mesenchymal cells obtained from the bone marrow was effective in the treatment of gonarthrosis by intra-articular injections. Even more recently, treatments aimed at treating the bone-cartilage interface in arthritic knees have been studied and proposed. In the 2016 Val et al. pilot study, stem cells from the tibial bone marrow injected into the percutaneous bone-cartilage interface were described as a new therapeutic approach to osteoarthritis of the knee. This procedure is able to repair cartilage by stimulating subchondral bone angiogenesis and alleviating ischemia associated with arthritic knee pain, generating extremely positive outcomes in patients with low-grade osteoarthritis and relieving long-term pain in patients with high-grade osteoarthritis. This treatment is also able to induce differentiation and proliferation of chondrocytes, leading to an increase in the size of the intra-articular matrix, demonstrating an effective and minimally invasive treatment for the resolution of OA. The study described here aims to evaluate the potential effectiveness of the synergistic effect of both injections, with the aim of improving the symptomatic picture of patients with OA of the knee. Combining percutaneous injections at the bone-cartilage interface with intra-articular injections will provide proven results for the use of stem cells such as cartilage repair, increased vascularity, and pain reduction, in both compartments of the knee affected by OA. The positive effects reported in the literature regarding intra-articular injections will be combined with those reported with respect to the use of percutaneous injections at the cartilage, in order to obtain a better outcome in the treatment of the disease than in previous studies.

Inclusion Criteria:

1. Male or female patients aged between 40 and 70;
2. Medial or lateral arthrosis (grade 2-3 according to Kellgren-Lawrence score);
3. Failure after at least 6 months of conservative treatment (patients not responding to drug therapy with NSAIDs and painkillers, no benefit from rehabilitation cycle in water or gym, no benefit after hyaluronic acid or platelet-rich plasma (PRP) infiltrations, or after at least one infiltration of corticosteroids);
4. Ability and consent of patients to participate actively in the rehabilitation and clinical and radiological follow-up protocol;
5. Signing of informed consent.

Exclusion Criteria:

1. Patients who are incapable of understanding and will;
2. Trauma patients within 6 months prior to surgery;
3. Patients with malignancies;
4. Patients with rheumatic diseases;
5. Patients with diabetes;
6. Patients with metabolic thyroid disorders;
7. Patients abusing alcoholic beverages, drugs or drugs;
8. Patients with lower limb impairment above 10°
9. Body Mass Index <18 or > 35;
10. Patients undergoing knee surgery during the 12 months prior to surgery;
11. Patients with pathology ascribable to patellofemoral pathology;
12. Untreated knee instability.

25 patients, meeting specific inclusion and exclusion criteria, will be enrolled. In general, the patients are characterized as patients with painful arthritis of the medial or lateral compartment, which have not achieved a reduction in pain in the presence of conservative treatments. The patients are enrolled on the basis of a paper questionnaire based on the inclusion and exclusion criteria: a patient can only be enrolled if he or she responds positively to all questions related to the inclusion criteria and negatively to all questions related to the exclusion criteria.