Conditions of the synovium involves changes in the synovial membrane, which lines the inside of the joints and produces synovial fluid - essential for lubrication and proper joint function. These conditions can include inflammation (synovitis), pathologic thickening (synovial hyperplasia), synovial follicles or benign tumor formations (e.g. pigmented vilonodular synovitis).

Symptoms include joint pain, swelling, stiffness and limited mobility. Diagnosis is done by imaging investigations such as ultrasound or MRI, sometimes supplemented by arthroscopy.

Treatment varies depending on the cause: from anti-inflammatory medicines and infiltrationsuntil arthroscopic procedures to remove the affected tissue.