Temporomandibular Joint Disorders

Epidemiology and Demographics

TMD affects 5-12% of the population with peak incidence at 20-40 years of age and is more common in females 1
Only 5% of TMD cases represent true intra-articular pathology involving the disc, while 85-90% are muscular in origin 2, 3, 1, 4

Internal derangement involves displacement of the articular disc, occurring with or without reduction 1, 5
Disc displacement is among the most frequently found TMJ disorders and can occur in anterior, lateral, or medial directions 1
When the disc is displaced, mechanical symptoms develop including clicking, locking, catching, and limited range of motion 5

Preservation and reattachment of the TMJ disc and lateral pterygoid muscle within the glenoid fossa sustains normal TMJ functionality and diminishes the likelihood of re-ankylosis following reconstruction 6, 7
The presence or absence of an intact articular disc significantly impacts surgical outcomes, with disc preservation associated with better long-term function 6, 7
MRI is the gold standard for evaluating disc position and ligamentous structures 1

The most important clinical distinction is recognizing that only 5% of TMD cases involve true disc pathology requiring invasive intervention, while 85-90% are muscular disorders treatable with conservative management 2, 3, 4
Approximately 50% of patients presenting with TMJ-region symptoms have complications unrelated to the TMJ itself, emphasizing the critical importance of accurate differential diagnosis before attributing symptoms to disc pathology 1, 4