The Diagnostic Challenge
Identifying the correct diagnosis allows the surgeon to anticipate the natural progression of the disease as well as provide treatment directed by evidence-based guidelines. Some of the more challenging diagnostic dilemmas include the following:
- • Arthralgia as a result of the inflammatory milieu versus the disc position
- • Condylar enlargement conditions
- • Condylar resorptive processes
- • Clinical conditions mimicking TMJ closed lock
- • Open lock
Our understanding of temporomandibular joint arthralgia has increased significantly over the last 40 years. The contribution of inflammatory cytokines to the development of arthralgia has become apparent as a result of synovial sampling. Multiple cytokines including IL-1 beta, IL-8, IL-17, CXCL-1, CCL-20, TNF-a, IFN-y, and TIMP-1 have been identified and found to correlate with pain, response to treatment, and/or the presence of internal derangement [4, 5]. Other interleukins also present possess anti-inflammatory properties including IL-4, IL-6, IL-10, IL-12, IL-13, and OCIF/OPG . The net result of the inflammatory process is the generation of reactive oxygen species including myeloperoxidase, superoxide ion, hydrogen peroxide, hydroxyl radical, and peroxynitrite anion. The result is the development of chondromalacia and degenerative joint disease. The inflammatory process also results in the release of VEGF, NGF, and FGF leading to changes in the synovial vascularity usually presenting as hyperemia and synovitis. The possibility that chronic inflammation results in a reduction of the biomechanical properties of the fibrocartilage, disc, and bone leading to disc displacement and/or degenerative changes cannot be excluded . However, the potential for disc displacement in an otherwise susceptible individual to lead to inflammation and/or degeneration cannot be excluded.
The presence of inflammation within the TMJ also appears to correlate with the presence of inflammatory biomarkers in the serum and saliva [8, 9]. The presence of inflammatory mediators within the temporomandibular joint and the correlation with pain provides an opportunity to treat these patients with anti-inflammatory medications. When patients fail to respond to systemic medication or when patients present with arthralgia and closed lock, the utility of arthrocentesis and arthroscopy becomes apparent. With few exceptions these procedures should be considered in most patients prior to any open procedure.
Although TMJ arthralgia can be explained by the presence of inflammatory mediators within the joint and/or disc position and health, the potential for peripheral and central sensitization to develop should not be underestimated [10, 11]. The presence of certain genetic polymorphisms may also predispose individuals to TMD. Furthermore multiple physiological and psychological domains may contribute to the development of TMD as well as multisystem dysregulation which is often seen in the same population [12, 13].
It seems prudent to proceed cautiously with any patient with temporomandibular joint arthralgia or closed lock first assuming that the pain is secondary to inflammation. Treatment strategies such as arthrocentesis and arthroscopy should be considered first. Arthroplasty to address disc position or structural abnormalities should be considered when the previous modalities have failed. Taking time to know the patient and carefully evaluating the response to prior surgical intervention will also allow the surgeon to develop rapport and identify comorbid psychological and physiological conditions that may make the patient a poor surgical candidate.