The aim of the study will be to evaluate the clinical efficacy of using ultrasound guidance during intra-articular injection of hyaluronic acid in the management of patients with TMJ internal derangement.

The temporomandibular joint (TMJ) represents one of the most biomechanically sophisticated and functionally critical articulations in the human body, serving as the primary interface between the mandible and the cranium.

This synovial joint facilitates essential orofacial functions including mastication, phonation, deglutition, and emotional expression through its unique ginglymoarthrodial (hinge-gliding) motion.

Temporomandibular disorders (TMDs) constitute a major public health burden, with epidemiological studies reporting prevalence rates ranging from 5% to 12% in global populations, though subclinical manifestations may affect up to 40% of adults.

The socioeconomic impact is substantial, with chronic TMD patients demonstrating significantly reduced quality-of-life indices comparable to conditions like rheumatoid arthritis, primarily due to persistent pain, functional limitations, and comorbidities with tension-type headaches and sleep disturbances.

Historically, TMJ research evolved from purely mechanical models to contemporary biopsychosocial paradigms that acknowledge multifactorial etiology.

Modern diagnostic frameworks, notably the Diagnostic Criteria for TMD (DC/TMD), emphasize the interplay between articular pathophysiology (e.g., disc displacement, osteoarthritis) and psychosocial dimensions (e.g., catastrophizing, depression), necessitating interdisciplinary management strategies.

Advances in molecular biology have elucidated genetic predispositions (e.g., COMT gene polymorphisms) and inflammatory cascades (IL-1β, TNF-α) that modulate pain sensitization and tissue degeneration.

Concurrently, innovations in diagnostic imaging-particularly dynamic MRI and cone-beam computed tomography (CBCT)-have revolutionized the evaluation of joint kinematics and microarchitecture, enabling earlier detection of degenerative changes.

The clinical management landscape continues to evolve toward minimally invasive biotherapies (e.g., platelet-rich plasma injections) and personalized rehabilitation protocols, though significant challenges persist in predicting treatment responsiveness.

Future research imperatives include validating biomarkers for early TMD detection, optimizing tissue-engineering approaches for condylar regeneration, and integrating artificial intelligence for phenotyping heterogeneous patient subgroups.

Inclusion Criteria:

1. Patients that will be diagnosed disc displacement confirmed clinically and by Magnetic Resonance Imaging (MRI).
2. Patient not responding to conservative therapy
3. Patients age must be (18 - 50).
4. Patients having painful joint, clicking sound, with or without limited mouth opening.
5. Patient's ability and desire to complete the treatment protocol and follow-up visits.

Exclusion Criteria:

1. Patient with an inflammatory or connective tissue disease
2. Patient with previous invasive TMJ surgical procedure.
3. Patient with Neurologic disorders
4. History of injection of any substance into the target TMJ during previous 6 months.
5. Patient with a history of bony adhesion.
6. Malignant disease in the head and neck region.
7. Patient with a psychological problem.
8. Patients having gross mechanical restrictions and condylar fracture