Internal TMJ derangement Flashcards
What is an internal derangement?
General orthopedic term implying a mechanical fault that interferes with the smooth action of the joint
The most common internal derangement is Disc Displacement
What does ginglymoarthrodial refer to?
The dual movement of the TMJ
What is internal derangement of the TMJ?
Abnormal relationship between the articular disc, mandibular condyle and glenoid fossa/ articular eminance.
The disc is most often displaced anteriorly or antero-lateral
With reduction or without reduction
What is the prevalence of internal derangement of the TMJ?
Main cause of TMJ internal derangement
Prevalence 40-50% patients with symptomatic TMD (Okeson)
What happens in disc displacement?
Anterior = Disc rests at anterior surface of the condyle
Medial = rests medial
Posterior = very rare (open lock which can be repaired soon after relatively soon after and muscle relaxants and splint therapy if delayed)
What is disc displacement with reduction?
Displaced disc recaptures its normal relationship with mandibular condyle during mouth opening.
How is internal derangement diagnosed?
CT or MRI are gold standard
What is disc displacement without reduction?
Displacement of the articular disc on closing, and failure to reduce or recapture the normal relationship with the condyle on opening
How does disc displacement evolve clinically?
With reduction -> Partial or complete
Disc displacement starts off acute -> chronic -> perforation -> degenerative joint disease (advanced osteoarthritis). Can also resolve spontaneously
What are the signs and symptoms of disc displacement with reduction?
Imaging
Reciprocal Clicking
Deviation of the mandible to the effected side early on opening (moves away from midline then returns)
Pain +/-
Limited mouth opening +/-
Soft end feel (Muscles stop mouth from opening but it can open further)
What causes the pain from disc displacement with reduction?
Articular pain (arthralgia)
Results from straining of ligaments
Condylar pressure against posterior attachments
Localised pain to TMJ
Increased pain with movement and use
What are the signs and symptoms of disc displacement without reduction?
Restricted opening
Mandibular midline deflection towards affected side (doesn’t return to midline)
Limitation of protrusion (plus some deflection to the ipsilateral side)
Limitation of lateral mvt to the contralateral side
Normal movt to effected side
Acute vs Chronic
What are the signs of acute disc displacement without reduction?
Sudden absence of joint clicking and restricted opening (mechanical interference)
Mandibular midline deflection
Limitation in protrusive and laterotrusive (contralateral movements)
Lots of pain
What are the signs of chronic disc displacement without reduction?
Slight limitation in mandibular opening
Slight deflection towards affected site
Crepitus
Pain +/-
Progressive improvement of opening due to elongation of posterior attachment and retro-discal ligaments. (pseudodisc forms which withstands condylar pressure because it is deprived of vascularisation and innervation)
What causes internal derangement?
Exact cause is not yet clear but any condition that cause elongation of the discal ligaments or thinning of the disc cause derangement.
Trauma (micro and macro)
Stress and adaptability
