Temporomandibular Joint Disorder (TMD)
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What is the Temporomandibular Joint Disorder (TMD)?
Temporomandibular disorders (TMD) is a diagnostic term for a range of musculoskeletal conditions affecting the TMJ. There are two main sources of dysfunction, the joint itself (arthrogenous) or the surrounding muscles and soft tissues (myogenous).
Joint-related disorders (arthrogenous)
Arthralgia
Pain that originates from the joint is called arthralgia. In TMD with arthralgia, symptoms may be provoked by certain jaw movements and functions.
Arthralgia may be caused by an irritation to pain-sensitive structures in the joint such as the retrodiscal tissue, ligaments around the disc (i.e. discal ligaments) or the joint capsule. Arthralgia may also be present due to disc displacement or degenerative joint disease.
Symptoms:
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Pain local to the TMJ itself
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Pain reproduced when palpating the TMJ
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Pain or stiffness with maximal jaw movements: opening, side-to-side, or pushing the jaw forwards.
Disc Displacement
A disruption to the functional movement of the articular disc alongside the mandibular condyle results in disc displacement. Disc displacement with reduction occurs if the disc returns to its normal position during jaw movement as the condyle moves further forwards. Disc displacement without reduction occurs when the disc remains displaced even with maximal possible mouth movement.
Disc displacement may occur with or without trauma. Usual causes are due to changes in disc morphology, loosening of ligaments that support the disc or a loss of functional muscle coordination (e.g. lateral pterygoids).
Symptoms:
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Clicking or locking
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Jaw deviation when opening
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Pain or inability to open the mouth fully
Image 1: Anterior displacement of the disc beyond its normal resting position on the mandibular condyle {Note: recommend linking a YT video/animation instead here}
Degenerative joint disease
Breakdown of the bony surfaces in the TMJ can be due to degenerative joint diseases such as osteoarthritis or rheumatoid arthritis. These conditions are more common in older individuals and occur due to chronic abnormal loading to the joint over many years or as a result of wider systemic medical issues⁵.
Symptoms:
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Crepitus or noise with jaw movement
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Jaw pain or stiffness
Subluxation and luxation
In cases where the TMJ has excessive movement or hypermobility, the mandibular condyle may remain caught anteriorly beyond the articular eminence. If the condyle is only stuck momentarily before returning to the mandibular fossa - either spontaneously or by self-manipulation (i.e. moving around the jaw), this is deemed a subluxation. However if the condyle remains stuck in a more severe manner which requires external assistance to be relocated into the mandibular fossa, this is deemed a luxation (or dislocation).
Image 2: Position of anterior subluxation or dislocation, where the condyle remains stuck anterior to the articular eminence
Subluxation/luxation may be caused by trauma, congenital weakness⁴ in TMJ ligaments or prolonged and excessive mouth opening⁴ (e.g. yawning or during dental/surgical procedures).
Symptoms:
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Jaw locking in a wide-open position.
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May be unable to close the mouth without self-manipulation or external assistance.
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Masseter muscle spasm and discomfort
Muscle-related disorders (Myogenous)
Myalgia (+/- pain referral)
Pain originating from the muscular and soft tissue structures is called myalgia. This can occur locally at a specific area, or may be felt as a spreading pain that can refer to another body structure remote to the source.
Causes of myalgia include stress, clenching/grinding or overuse, leading to muscular overactivity in the TMJ muscles. Symptoms may directly relate to intensity or quantity of activity⁵.
Symptoms:
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Pain described as dull, achy, tender or tight.
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Jaw stiffness
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Headaches
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Reproduction of pain on palpating TMJ muscles
Treatment options
Hands-on treatment options such as soft tissue release (e.g. massage, dry needling) and ultrasound can be useful in reducing pain and overactivity in the TMJ muscles.
Since most TMD patients have joint restrictions, manual therapy techniques (i.e. joint glides) are also a useful treatment option for decreasing joint pain and sensitivity. This often opens up greater opportunities for exercise and functional ability.
Therapeutic exercise and education regarding activity modification can be provided to unload the joint and manage pain, while also building back muscular strength and coordination to help support the TMJ during everyday use.
Reference
¹https://www.youtube.com/watch?v=mB468Jh9aAY&ab_channel=AlilaMedicalMedia
²Mercuri L. G. (2008). Osteoarthritis, osteoarthrosis, and idiopathic condylar resorption. Oral and maxillofacial surgery clinics of North America, 20(2), 169–vi. https://doi.org/10.1016/j.coms.2007.12.007
³https://www.slideshare.net/Zee1991/subluxation-and-dislocation-of-temporomandibular-joint
⁴https://www.nursingcenter.com/ce_articleprint?an=01261775-201607000-00003
⁵Lobbezoo, F., & Naeije, M. (2006). Wetenschappelijk gefundeerde behandeling van temporomandibulaire dysfunctie. Bezint eer ge begint! [Evidence-based management of temporomandibular dysfunction. Think before you begin!]. Nederlands tijdschrift voor tandheelkunde, 113, 14–17.