Temporomandibular Joint Dysfunction: an Osteopractic Physical Therapy Perspective

Ten years ago, therapeutic ultrasound and massage were found to be ineffective for chronic low back pain, a conclusion that was again confirmed this year.1,2 Notably, the most recent clinical practice guidelines don’t even mention ultrasound or massage for consideration in the treatment of LBP.3 Unfortunately, many of the treatment options taught to physical therapists 20 years ago for low back pain and many other areas still persist today.

Although physical therapists have treated temporomandibular dysfunction (TMD) for decades, most patients that suffer from the condition do not pursue treatment from a physical therapist. This may be due to limited referral source knowledge of conservative treatment options for TMD, a general public misperception of the “physical therapy brand”, and the apparent lack of high-quality outcome studies demonstrating effectiveness of physical therapy for TMD.

Nevertheless, there are several new and emerging conservative treatment approaches for the management of TMD that appear to be showing some promise in both clinical practice and recent outcome studies.

CLASSIFICATION & MANAGEMENT

In 2014, a breakthrough article offered an evidence-based, classification schema for TMD.4 This article by Harrison et al.4 expanded on the vague 1983 American Dental Association definition of TMD, which simply reads, “pathologies or conditions affecting the temporomandibular joint, masticatory muscles, and closely related structures”.5 Harrison et al.4 also took the International Headache Society6 definition of TMD and the pre-established Research Criteria for TMD into consideration.7-12 Much like the treatment-based classification of the lumbar and cervical spines13, 14 has been helpful for classifying patients and subsequently providing appropriate treatment, updated guidelines are now available for TMD.

The diagnostic classification identified two axes of focus for examination: Axis 1 – physical examination of body impairments and Axis 2 – identifying psychosocial characteristics that play a role in pain complaints.7–12 While both are equally important for consideration in the management of TMD and other pain conditions, this article will focus primarily on Axis 1. According to Axis 1, there are three broad classification groups of TMD: (1) Masticatory muscle disorders, (2) Joint disorders related to temporomandibular disc derangements, and (3) Joint disorders related to TMJ arthralgia.

CLASSIFICATION I

Classification 1 addresses the muscles of mastication that are directly injured through overuse/tensile strain, and indirect muscle guarding and/or central mediated myalgia. Symptoms may involve local pain, referred pain (ear, tooth, TMJ, face, or cranial regions), limited or painful mouth opening, or vertigo. Masticatory muscles that were specifically selected due to their role in TMD were the lateral pterygoid, medial pterygoid, masseter and temporalis. These muscles may be directly targeted by PTs via dry needling (DN) 17 or indirectly through the use of high-velocity low-amplitude thrust manipulation of the cervical spine.15, 16

In 2010, Oliveira-Campelo et al.15 studied the immediate effects of thrust manipulation directed at the atlanto-occipital (OA) joint on trigger points in the masseter and temporalis along with mouth opening. They found that OA thrust manipulation produced significant improvements in active mouth opening and pressure pain thresholds in the masseter and temporalis muscles.

Additionally, Mansilla-Faragut et al. demonstrated a statistically significant, 3.5mm improvement in mouth opening and improved pressure pain thresholds over the sphenoid bone post OA manipulation compared to control.16 Furthermore, Shin et al.17 found that manual therapy and dry needling with the needles left in situ for 20 minutes at common acupoints associated with the muscles of mastication decreased pain and improved mouth opening.

While these findings are consistent with dry needling studies that target trigger points,18–20 the inaccessibility of manual palpation of the pterygoid muscles25 and the limited reliability of localizing trigger points26 suggests that outcomes are likely a general result of needling muscle and connective tissue associated with the TMJ. Notably, Dıraçoğlu et al.27 reported positive clinical outcomes when trigger points in the masticatory muscles were needled and also when needles were inserted superficially in non-trigger point locations.

CLASSIFICATION II

The second TMD classification addresses joint impairments involving the temporomandibular disc, joint surfaces, joint capsule, ligaments, synovium or a combination thereof. Problems with these tissues are often manifested through faulty arthokinematics of the TMJ disc, which can be classified as disc displacement with reduction (DDWR) or disc displacement without reduction (DDWOR).

Notably, most patients with joint clicks or pops do not have pain or dysfunction; therefore, conservative management with education about the remodeling process, maintenance of healthy joint function and the role of stress in over activation of the masticatory muscles is recommended. Nevertheless, as type II TMD patients progress from DDWR to DDWOR, mouth opening may become restricted due to an inability of the condyle to glide anteriorly. When this occurs, preauricular pain may result from retrodiscal tissue inflammation or excessive joint loading.

In this situation, it is important to remember the role of the lateral pterygoid and its attachment to the articular disc and retrodiscal tissue. During mouth opening, the lateral pterygoid (inferior head) assists to glide the mandible forward and pull the articular disc forward. The lateral pterygoid (superior head) is primarily active during mouth closing, so as to ensure proper tracking of the disc on the mandibular condyle.

When anterior disc displacement is combined with posterior capsule degeneration, previous studies have demonstrated that the superior head is no longer able to effectively manage the disc, resulting in compensation and subsequent overuse of the inferior head.28-29 Importantly, when DDWR is diagnosed, an “S” pattern may be present. When DDWOR is present, there will likely be limited opening and no joint sounds.

In both of these scenarios, manipulation to the upper cervical spine and deep dry needling targeting the lateral pterygoid may be beneficial. Anecdotally, needling the lateral pterygoid, especially the inferior head, can bring an immediate abolition to joint sounds during mouth opening. To aid further with mouth opening, non-thrust mobilization directed to the TMJ may be useful.21, 23-24

CLASSIFICATION III

Group III TMD includes those patients that suffer from joint pain and inflammation of the soft tissues, to include the capsule, ligaments, synovium, and retrodiscal structures. Intra-articular structural changes also fall into category III and are common secondary to arthralgia, osteoarthritis and osteoarthrosis. Prolonged loading and/or chemical irritation seems to play role in generation of this condition.

Additionally, Nikolakis et al.22 found that localized intra- and extra-capsular pain “may cause muscle splinting of the surrounding musculature…a reflex response to protect a threatened part from damage.” From a symptom standpoint, these patients may report a crepitus or grating feeling throughout the entire joint movement.

Notably, Harrison et al.4 stated, “It is important to note that the TMJ does demonstrate normal age-related changes such as slight flattening of the condyle, but age-related adaptive processes do not predispose one to pain or dysfunction in this region.” Manual therapy and specific exercises have been shown to aid Group III TMD patients even at 6 months follow-up.22 That is, joint degeneration does not necessarily indicate that physical therapy will be ineffective.

Group III TMD patients require a thorough examination of the muscles of mastication in an effort to decrease pain and improve joint kinematics. Manual therapy to improve capsular mobility is recommended24 and has been shown to be beneficial.22 Dry needling the joint capsule may further be beneficial to stimulate healing and the remodeling process.

CONCLUSIONS

Following appropriate classification and direct symptom management, it is important to consider the causative role of sustained trunk postures.23 This may be especially true for unilateral TMD patients.

Olson and Furto23 have hypothesized that prolonged forward head posture places the mandible in a more retruded position and, therefore, changes the trajectory of the mandible. Head positions that place increased stress on the posterior cervical structures (e.g. prolonged forward head posture) may further cause the posterior and posterolateral cervical musculature to develop trigger points, which may reflexively impact the arthrokinematics of the TMJ through the trigeminocervical nucleus and its relationship to the muscles of mastication via cranial nerve V.15

Linkages between the artho- and osteo-kinematics of the shoulder, cervical spine, thoracic spine, and scapulothoracic region further suggest that upper quarter movement dysfunction (e.g. frozen shoulder, prolonged upper quarter immobilization) may adversely affect the TMJ. Cases of recalcitrant TMD may therefore require screening seemingly unrelated or remote areas to identify regionally interdependent components that may be generating, maintaining, or contributing to the syndrome.

AUTHOR:

James Escaloni, DPT, OCS, Cert. MDT, Dip. Osteopractic
Residency Faculty, Select Medical & KORT Orthopaedic Residency
Fellow-in-Training, AAMT Fellowship in Orthopaedic Manual Physical Therapy
Clinic Director, KORT Physical Therapy, Lexington, KY

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