Figure 5: Proposed flow chart for intra-articular injection therapy: Once TMJ OA diagnosis is confirmed, through patient history, physical examination, and MRI images, the presence or absence of joint effusion will determine the need for lavage and anti-inflammatory medications. In cases where joint effusion is absent, an assessment of the TMJ OA stage of progress should be conducted. If only cartilage erosion or both cartilage and bone erosion are observed, hyaluronic acid or injectable platelet-rich fibrin should be selected, respectively. If joint effusion is present, the location of the signal on MRI (i.e., in the superior or inferior joint spaces) will determine the space subjected to joint lavage under arthrocentesis. Following superior joint space arthrocentesis, the selection of intra-articular injection therapy will depend on the presence of primary inflammatory effusion (inflammatory phenotype) or secondary inflammatory effusion (other phenotypes), with corticosteroid or hyaluronic acid being chosen, respectively. In cases where joint effusion is observed in the inferior joint spaces of the TMJ, after arthrocentesis, intra-articular therapy should be selected based on the TMJ OA stage of progress, as previously described.