Radiological imaging of temporo-mandibular joint diseases.

Dr/ ABD ALLAH NAZEER. MD.

IntroductionTemporomandibular joint (TMJ) connects the mandible or the lower jaw to the skull and regulates the movement of the jaw . The TMJ is one of the most complex, delicate and highly used joints in a human body. The most important functions of the TMJ are mastication and speech. Temporomandibular disorder (TMD) is a generic term used for any problem concerning the jaw joint. Injury to the jaw, the TMJ, or muscles of the head and neck can cause TMD. Other possible causes include grinding or clenching the teeth; dislocation of the disc; presence of osteoarthritis or rheumatoid arthritis in the TMJ; stress, which can cause a person to tighten facial and jaw muscles or clench the teeth; aging. The most common TMJ disorders are pain dysfunction syndrome, internal derangement, arthritis, and traumas. TMDs are seen most commonly in people between the ages of 20 and 40 years, and occur more often in women than in men. Some surveys have reported that 20-25% of the population exhibit one or more symptoms of TMD .

TMJ anatomy and functionTMJ is a bi-condylar joint in which the condyles, the movable round upper ends of the mandible, function at the same time (Figure 1). Between the condyle and the articular fossa is a disc made of fibrocartilage that acts as a cushion to absorb stress and allows the condyle to move easily when the mouth opens and closes.The bony structures consist of the articular fossa; the articular eminence, which is an anterior protuberance continuous with the fossa; and the condylar process of the mandible that rests within the fossa. The articular surfaces of the condyle and the fossa are covered with cartilage. The disc divides the joint cavity into two compartments, superior and inferior. The two compartments of the joint are filled with synovial fluid which provides lubrication and nutrition to the joint Structures . The disc distributes the joint stresses over broader area thereby reducing the chances of concentration of the contact stresses at one point in the joint.The presence of the disc in the joint capsule prevents the bone-on-bone contact and the possible higher wear of the condylar head and the articular fossa. The bones are held together with ligaments. These ligaments completely surround the TMJ forming the joint capsule.

Radiology MRI is best technique for joint spacepathology CT is best technique for bony pathology Plain films with arthrography sometimes useful, although largely replaced by MRI and CT Arthroscopy is also diagnostic

Congenital Anomalies Fairly rare Important to identifyabsence of growth plates leads to severe deformities condylar agenesis, condylar hypoplasia, condylar hyperplasia and hemifacial microsomia most common

Condylar agenesis– the absence of all or portions of condylar process, coronoid process, ramus or mandible– other first and second arch anomalies seen– early treatment maximizes condylar growth a costocondral graft may help with facial development

Panoramic view and CT Scan show absence of left condylar head.

Condylar hypoplasia– usually developmental secondary to trauma or infection– most common facial deformity is shortening of mandible jaw deviates towards affected side– Tx for child: costochondral graft– Tx for adult: shorten normal side of lengthen involved side.

– an idiopathic, progressive overgrowth of mandible deviation of jaw away from affected side– presents in 2nd decade– Treat by condylectomy

Bifid condyle.

Traumatic Injuries. Fractures of the condyle and subcondyle are common– unilateral fracture involves deviation of jaw towards affected side with or without open bite Tx: MMF with early mobilization– bilateral fracture usually has anterior open bite often requires ORIF of one side with MMF

Dislocation of the TMJ. Acute dislocation:– new onset Type III derangement, surgery of the mouth– treatment is reduction under anesthesia Chronic dislocation:– usually secondary to abnormally lax tendons– Tx: sclerosing agents, capsulorraphy, myotomy of lateral pterygoid

Condylar process fractures(High neck).

TMJ dislocation - bilateral CT scan showing empty glenoid fossae with TMJ dislocation.

Arthritis of the TMJ The most frequent pathologic change of the TMJ Most are asymptomatic Rheumatoid arthritis– usually seen in other joints prior to TMJ– when present, both joints usually affected– early radiographic changes include joint space narrowing without bony changes

•Rheumatoid Arthritis: – late radiographic changes may involve complete obliteration of space with bony involvement and even ankylosis– end stage disease results in anterior open bite– Juvenile RA may progress to destruction of the growth plate, requiring costochondral graft

Rheumatoid arthritis.

Advanced osteoarthropathy of the TMJ.

Degenerative Arthritis: – Primary Degenerative arthritis “wear and tear” - usually in older people asymptomatic or mild symptoms– Secondary Degenerative arthritis due to trauma, infection and bruxism symptoms severe Radiographic findings include osteophytes and erosion of the condylar surface.

Ankylosis of the TMJ Definition: the obliteration of the joint space with abnormal bony morphology– etiologies include prolonged MMF, infection, trauma, DJD False ankylosis: an extra-capsular condition from an abnormally large coronoid process, zygomatic arch or scar tissue

Ankylosis.

Internal derangement of the temporo mandibular joint (TMJ): is defined as a disruption within the internal aspects of the TMJ in which there is a displacement of the disc from its normal functional relationship with the mandibular condyle and the articular portion of the temporal bone. Internal derangement of the temporomandibular joint (TMJ) is characterized by displacement of the intra-articular disc, results in clicking or popping sounds. The displacement of the articular disc does not always cause a mechanical obstruction .Those conditions may be painless or may be associated with pain, especially during function. The most common causes are trauma , which results in a sudden displacement of the disc, or chronic para function, which ends up in degenerative changes in the articular surfaces, increased friction, and gradual disc displacement.

A 3D graphic lateral view of the temporomandibular joint with the capsule partially removed depicts the normal position of the articular disc between the articular eminence of the temporal bone (AE) and the mandibular condyle (C) with the mouth closed. The articular disc demonstrates a thicker anterior band (AB) and posterior band (PB) separated by a thinner intermediate zone (IZ). The bilaminar zone (BZ) and the superior (SLP) and inferior (ILP) bellies of the lateral pterygoid muscle are also indicated.

Internal derangement:

Types of disc displacement at the TMJ.

T1-Weighted sagittal magnetic resonance images in (a) closed- and (b) open-mouth positions showing normal disc positions (arrows).

T1-Weighted sagittal magnetic resonance images in (a) closed- and (b) open-mouth positions showing anterior disc displacement with reduction (arrows).

A, Closed mouth sagittal oblique T2 fat-suppressed MR image of left TMJ demonstrates larger posterior band (open arrow) lies over the mandibular condyle (MC), thin intermediate zone (red arrow) between the MC and posterior part of the articular eminence (AE) while the anterior band (blue arrow) is located under the AE. B, Open mouth sagittal oblique T2 fat-suppressed MR image of the same side shows normal translation of MC which reaches under the apex of the AE and thin intermediate zone (yellow arrow) is located over the condyle and thus the posterior band (white arrow) and retrodiskal tissue (brown arrow) are more clearly depicted. Note the location of anterior band (pink arrow) in open mouth view.

Anterior disc displacement with reduction and joint effusion.

Disc displacement with reduction (DWR): The posterior band of the disc is located anteriorly.

Presurgical magnetic resonance of temporomandibular joint showing disc displacement with reduction (A and B), and 10 years after mandibular surgical advancement (C and D) showing the maintenance of the disc status and the onset of condylar degeneration

Anterior-lateral displacement demonstrated by magnetic resonance fast spin-echo DP-weighted images in the sagittal (A to E) and coronal (F to L) planes in closed-mouth position. Sagittal sections in the first line show the displacement of the articular disc, which bulges anteriorly and laterally against the joint capsule (black arrowheads). The lateral component of the displacement is better recognized in the coronal sections in the second line (white arrowheads). The morphology of the disc is irregular and wavy. The disc also shows a tendency to bend and fold over the lateral aspect of the joint capsule (B and I). Multidirectional displacements are more common than unidirectional ones.

Anterior displacement of the articular meniscus in relation to the mandibular condyle in closed-mouth position with no reduction at open mouth.

Closed-mouth position (A), the T2*-weighted MR image suggests anterior displacement of the articular disc, whose posterior band is positioned beyond the condylar head (large arrow). In the open-mouth position (B to C), the two spatially adjacent T2*-weighted MR images confirm a nonreducing disc displacement, as the disc is located anteriorly to the articular eminence and the condylar head (small arrows). The shape of the disc is deeply altered and its structureis twisted. Concurrently, the roundness of the condylar head is reduced and, just below its articular surface, MR signal alterations can be found. Based on these MRI findings, a stage IV disc derangement might be suspected, because the displacement was not reduced by jaw opening. However, the patient had been clinically classified as a stage II disc derangement, because he was asymptomatic and had referred only occasional episodes of limited mouth opening and intermittent locking. Physical examination had shown normal opening range of the mouth. This may be sensed fromthe MR images in the open-mouth position (B, C) as the condylar head appears beyond the articular eminence.

T1-Weighted sagittal magnetic resonance images in (a) closed and (b) open-mouth positions showing anterior disc displacement without reduction (arrows).

Oblique sagittal fat-suppressed proton density weighted-image through the closed left TMJ in a 23yo female with jaw pain and popping. The articular disc is anteriorly displaced and is thickened centrally. Small joint effusions are seen within the superior and inferior joint compartments. (arrows).

Oblique sagittal proton density-weighted image through the closed left TMJ in a 23yo female with jaw pain, popping and locking. The articular disc is anteriorly displaced and is buckled centrally (arrow). The posterior band is thickened (arrowhead).

Anterior disc displacement without reduction.

Sagittal T2-weighted magnetic resonance image shows fluid effusion in superior joint cavity (arrow) and anterior displacement and folded deformity of articular disc (arrowhead

Sagittal T2-weighted magnetic resonance image in open-mouth position shows fluid effusion in the superior joint space (arrows) and high signal intensity in the glenoid fossa indicating retodiskitis (arrowhead).

Sagittal view of the MRI in the closed mouth position in a patient with internal derangement of the left TMJ. Anterior disc displacement, hypoplastic condyle, destruction of the disc. Changes of bone structures, effusion in the anterior recess.

Magnetic resonance imaging (MRI) of temporo mandibular joint osteoarthritis (TMJ OA) combined with disc displacement (DD) is shown. (A and B) showed early TMJ OA combined with DD; (C) and (D) showed intermediate TMJ OA combined DD; (E and F) showed late TMJ OA combined with DD; (A, C and E) closed position; (B, D and F) open position. Green arrow, disc perforation.

Disc perforation and features of degenerative joint disease.

Oblique sagittal proton density weighted image through the closed left TMJ of a 30yo female with chronic jaw pain. The articular disc is anteriorly displaced and lies beneath the articular eminence (arrowhead). The disc is thickened and foreshortened (asterisk). Immediately below the displaced disc lies the markedly thickened tendon of the inferior belly of the lateral pterygoid muscle (arrow). This appearance has been described as a "double disc" sign.

Oblique sagittal T1-weighted image of the closed left TMJ in a 30yo female with jaw pain, clicking, and limited motion. The articular disc is anteriorly displaced and is thinned posteriorly (arrow). The joint is narrowed with early osteophytes at the condylar head. Marrow edema within the condylar head is reflected by decreased signal intensity of the marrow instead of the fatty marrow signal normally seen within the condyle (arrowheads).

Sagittal T1-weighted magnetic resonance image in open-mouth position of osteoarthritic joint shows osteophyte formation (arrowhead) and anterior displacement and folded deformity of articular disc (arrow)

Neoplasms of the TMJ Uncommon Usually benign– chondromas, osteomas, osteochondromas– fibrous dysplasia, giant cell reparative granuloma and chondroblastoma rare-Malignant tumors such as fibrosarcoma and chondrosarcoma very rare.

Left condylar osteoma.

Osteochondroma.

Left condylar chondrosarcoma.

Osteosarcoma of the left mandible.

Mandibular Condylar Metastasis.

Positron emission tomography/computed tomography revealed the primary tumour within the left pulmonary lingula (dashed white arrow), hilar and subcarenal nodes (solid white arrows), a thoracic vertebral metastasis (yellow arrow) and the condylar metastasis (grey arrow).

Metastasis of the left mandible from lung cancer.

Thank You.