Intraarticular TMJ pain and dysfunction – 2024 – invited guest editorial

It is important to recognize that the term temporomandibular disorders (TMD) is an umbrella term (similar to saying “back problems”). Therefore, it does not make a distinction between arthrogenous and myogenous sources of pain and dysfunction. In order to optimize patient outcomes, it is critical that clinicians make the distinction and therefore the correct diagnosis [1,2]. Distinguishing between arthrogenous and myogenous pain can be readily made by following the history taking and physical examination procedures described in the validated Diagnostic Criteria/Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications [3].

The source of intra-articular pain and dysfunction within the temporomandibular joint (TMJ) has historically been described by some as being secondary to the intra-articular disc position. The articular disc and condyle relationship was thought to be the most important factor in the development of intra-articular pain and dysfunction (IPD) [4]. This erroneous focus on purely mechanical sources of IPD fails to appreciate the complexity of how pain and dysfunction can arise within any joint, including the TMJ. The TMJ is a complex anatomical structure with bone, cartilage, articular disc, blood vessels, lymphatics, and nerves, as well as muscles that move the joint, all of which must be considered when dealing with any joint disorder [5]. The historical focus on the mechanical relationship between the articular disc, condyle, articular eminence, and glenoid fossa evolved in the late 1970’s, and led to the simplistic concept of “internal derangement” (ID) which was thought to account for arthrogenous TMD symptoms. Traditional treatment approaches have focused on ID which was categorized using the Wilkes criteria. More recently, basic science as well as translational and clinical research has clearly demonstrated that the pathophysiology of IPD involves various combinations of factors such as synovitis, capsular impingement, and several types of symptomatic disc displacement (SDD) [6].

The importance of recognizing the potential causes of IPD is that it provides clinicians and patient with treatment options that are non-surgical, including anti-inflammatory and biologic medications to treat inflammation, as well as minimally invasive intra-capsular procedures such as arthrocentesis and arthroscopy to further manage inflammation, capsular impingement and SDD. These treatment approaches are simple, patient centric, and result in predictable and positive patient reported outcomes for the majority of patients. However, the success of these conservative procedures depends heavily on making the correct initial diagnosis as well as selecting the most appropriate evidence based treatment(s) for each individual patient. The need to treat SDD or osteoarthritis with open procedures such as arthroplasty or total joint replacement (TMJR) should be considered only if non-surgical and minimally invasive procedures have failed to adequately manage the IPD.

To ensure that the management of patients with IPD is contemporary and evidence based, it behooves clinicians and patients to recognize the potential causes of IPD, and adopt appropriate treatments that do not initially focus on disc position. The “need” to address disc position at all has greatly diminished as studies have demonstrated how most TMJ’s can adapt to having a malpositioned disc. This will allow the vast majority of patients to find resolution to their pain while avoiding open procedures unless absolutely necessary [7,8].

There is considerable opportunity to educate those who manage patients with TMDs, including IPD, to ensure that patients receive the most ideal evidence-based treatment. These educational activities are the responsibility of the expert community both within academic institutions as well as in various continuing education settings. With proper training, the healthcare community that manages TMDs should focus on:

• Making the correct diagnosis which requires an understanding of orofacial pain, including arthrogenous and myogenous causes of TMD symptomatology

• Pursuing continuing education opportunities to ensure that current and contemporary evidence-based treatments are adopted

• Appreciate the presence of psychosocial factors and comorbid pain conditions which have a significant and negative prognostic impact on patient outcomes.

• Adopt a non-surgical and minimally invasive approach to IPD before any open surgical procedure is considered

• Appreciate that there are some patients for whom the prognosis is poor. This may be the result of challenges in making the correct diagnosis, significant psychosocial conditions, the presence of centrally mediated or neuropathic pain conditions, or a history of poor outcomes despite the use of reasonable treatment protocols.

• Ensuring that both the patient and the healthcare professional have realistic and similar expectations for any treatment that is provided

• When indicated, adopting the most predictable and least morbid evidence-based surgical approach for open surgical procedures, including total joint reconstruction

• Preventing and managing complications appropriately

• Support for continued research to improve understanding of the pathophysiology of TMDs, including IPD, as well as identifying the least invasive and most predictable treatment options for each individual patient.

The opinions expressed above are based on the most current evidence-based literature, recommendations of the National Academy Science Engineering and Medicine [9], the US National Institute of Dental and Craniofacial Research [10], the American Academy of Orofacial Pain Guidelines [11], and the Special Committee for Temporomandibular Joint Care (American Association of Oral and Maxillofacial Surgeons) whose goals are to advance the understanding of TMDs and optimize patient outcomes [12].