The gut microbiome appears to be a significant contributor to musculoskeletal health and disease. Microbiome composition and its functional implications have been associated with prevention of bone loss and/or reducing fracture risk. Genetic background, gender, dietary intake, and social factors are also important factors which contribute to the musculoskeletal health, as well as to the normal balance of intestinal microbiota. The link between gut microbiota and joint inflammation in murine models of arthritis has been established, and it is now receiving increasing attention in human studies. Recent papers have demonstrated substantial alterations in the gut microbiota in patients with rheumatoid arthritis (RA) and osteoarthritis (OA). These alterations resemble those established in systemic inflammatory conditions (inflammatory bowel disease, spondyloarthritides, psoriasis), which include decreased microbial diversity and lower abundances of bacteria belonging to the Firmicutes phylum that are known to have immunoregulatory properties.These new findings open important future horizons both for understanding disease pathophysiology and for developing novel biomarkers and treatment strategies. Further investigation into the mechanisms linking changes in the microbiome to alterations in bones and joints is necessary. Next Generation Sequencing, metatranscriptomic analysis, and metabolomic approaches may provide yet-greater insight and help further understand these mechanisms. To investigate gut microbiota change will be associated with the sintoms of knee and / or hip OA in italian patients.

Inclusion Criteria:

• All subjects will have hip or knee OA according on radiographic findings (Kellgren-Lawrence scale ≥3). A physiatrist (physician) will establish the diagnosis of pain-OA.

Exclusion Criteria:

• Psychiatric or neurological disorders, celiac disease, lactose intolerance, or allergies or other ongoing illnesses (i.e., irritable bowel syndrome, diabetes, ulcerative colitis, etc.) or recent antibiotic treatment (i.e., <3 months before the beginning of the study).
• Participants require treatment with aspirin > 325 mg /day.
• Participants who smoked more than 10 cigarettes per day were excluded.
• Participants will be excluded also if they score greater than 6 points on the Beck Depression Inventory (BDI) or more than 30 points in the State Trait Anxiety Inventory (STAI), dementia and not Italian speaking due to the high level of language skills required for questionnaires and quantitative sensory testing.
• Post-traumatic OA (e.g., fractures), congenital hip deformities, surgical interventions to the hip or knee, Legg-Calvé-Perthes disease, or degenerative or non-degenerative neurological conditions in which pain perception is altered will be excluded