radiographic imaging of tmj

Diagnostic Imaging of the Temporomandibular Joint

Fares H. Hanafieh & Fahad F. Salehi

What is the Temporomandibular joint?

Unique in that it constitutes of two separate joints anatomically and they function together as a single unit

Consists of: CondylesArticular DiscMandibular Fossa

Has a fibrous capsule that surrounds and encloses the joint

CONDYLE:

- Shape of condyle varies considerably

- Superior aspect maybe flattened,

rounded or markedly convex

- Mediolateral contour is usually slightly

convex

- Variations in shape may cause difficulty

with radiographic interpretation

- Extreme aspects of the condyle are the medial

pole and lateral pole

MANDIBULAR FOSSA: Composed of the glenoid fossa and atricular eminence.

INTERARTICULAR DISK: - Between condylar head and

mandibular fossa

- Biconcave shape

Disorders of the temporomandibular joint are abnormalities that interfere with the normal form or

function of the joint

Disorders of the

Temporomandibular Joint1- Developmental Abnormalities

2- Soft Tissue Abnormalities

Developmental Abnormalities:

1- Condylar Hyperplasia

2- Condylar Hypoplasia

3- Juvenile Arthrosis

4- Coronoid Hyperplasia

5- Bifid Condyle

1- Condylar Hyperplasia:

- Enlargement and deformity of the condylar head

- Secondary effect on the mandibular fossa as it remodels to accommodate the abnormal condyle

Etiology: Trauma, infection, hereditary

More common in males

Self limiting

Progresses slowly or rapidly

Mandibular asymmetry

Chin deviated to the affected side

Radiographic Features:

May appear normal but symmetrically enlarged

Maybe more radiopaque due to additional bone present

Condylar neck may be elongated

Glenoid fossa may also be enlarged

Ramus and mandibular body on the affected side also may be enlarged, resulting in a characteristic depression of the inferior mandibular border

The affected ramus may have increased vertical depth and may be thicker in the anteroposterior dimension

D/D: - Osteochondroma

- Condylar osteoma or osteophyte that occurs in chronic degenerative joint disease

Treatment:

Orthodontics combined with orthognathic surgery

2- Condylar Hypoplasia

Failure of the condyle to attain normal size because of congenital and developmental abnormalities or acquired diseases that affect condylar growth.

The condyle is small, but condylar morphology is normal

Underdeveloped ramus and occasionally mandibular body

Unilateral or bilateral


The condylar neck and coronoid process usually are very slender and are shortened or elongated in some cases

The ramus and mandibular body on the affected side may also be small, resulting in a mandibular asymmetry and occasional dental crowding, depending on the severity of mandibular underdevelopment

D/D: Juvenile rheumatoid arthritis and arthritic conditions

Treatment: orthognathic surgery

bone grafts

orthodontic therapy maybe required

3- Juvenile Arthrosis:

Manifests as hypoplasia and characteristic morphologic abnormalities

May be a form of condylar hypoplasia

It affects children and adolescents during the of mandibular growth

More common in females

Incidental finding in a panoramic projection

Radiographic appearance:

Condylar head develops a characteristic “toadstool” appearance

Condylar neck is shortened or even absent in some cases

D/D: developmental hypoplasia

rheumatoid arthritis

* Treatment: orthrognathic surgery

orthodontic therapy

4- Coronoid Hyperplasia:

- acquired or developmental

- elongation of the coronoid process

- developmental -> bilateral

acquired -> uni or bilateral

- inability to open mouth

- painless

- Radiographic features:

Best seen in panoramic,

Waters, and lateral tomographic views and on CT scans

TMJs usually appear normal

-D/D: Unilateral cases should be differentiated from a tumor of the coronoid process (osteochondroma or osteoma)

Unlike coronoid hyperplasia, tumors have an irregular shape

-Treatment: surgical removal or the coronoid process and postoperative physiotherapy

5- Bifid Condyle:

Vertical depression,

notch, or deep cleft

in the center of the condylar head

Rare, often unilateral

Incidental finding

Some patients may have sings of TMDs (noises + pain)


Depression on the superior condylar surface giving a heart shape

D/D: Vertical fracture through the condylar head

Treatment: Not indicated unless pain or functional impairment is present

Soft Tissue Abnormalities

Internal Derangements - abnormality in the articular disc and may interfere with normal function

- Cause is unknown

- Internal derangements can be diagnosed by MRI

Clinical Features:

- found in both symptomatic and healthy pts

- symptomatic pts may have a decreased range of mandibular motion

-displacements may be unilateral or bilateral


- MRI is the technique of choice

Disc Displacement:

- Anterior displacement is most common

- The articular disc is located anterior to the condylar head

Disk reduction and nonreduction:

- reduction is when an anteriorly displaced disk may reduce to a normal relationship with the condylar head during any part of the mouth opening movement

- nonreduction is when the disk remains anteriorly displaced and will undergo permanent deformation.

Perforation and Deformities:

- perforations between the superior and inferior joint spaces most commonly occur in the retrodiskal tissue, just behind the posterior band of the disk

- Not reliably detected with MRI

Fibrous Adhesions and Effusion:

- Fibrous adhesions are masses of fibrous or scarred tissue that form in the joint space, particularly after TMJ surgery

- Joint Effusion means fluid in the joint and is considered to be and early change that may precede degenerative joint disease

- Both can be detected by MRI

Remodeling and Arthritic conditions

1- Remodeling:

- Adaptive response of cartilage and osseous tissue to forces applied to the joint that maybe excessive, resulting in alteration of the shape of the condyle and articular eminence

- no destruction or degeneration of articular soft tissue occurs

- occurs throughout adult life

- considered abnormal only if it is accompanied by clinical signs and symptoms of pain or dysfunction

- Radiographic Features:

- flattening

- cortical thickening of articulating surfaces

- subchondral sclerosis

-D/D: flattening and subchondral sclerosis maybe difficult to differentiate from early degenerative joint disease

- Treatment:

- Only indicated when signs and symptoms are present. (ex. Splint therapy)

2- Degenerative joint disease (osteoarthritis):

- non inflammatory disorder of the

joints characterized by

joint deterioration and proliferation

- can occur at any age (incidence increases with age)

- female predominance

- asymptomatic or pts may complain of signs + symptoms of TMJ dysfunction

- Radiographic features:

- more accurately seen in CT but gross osseous changes maybe evident in MRI studies

At the maximum intercuspation joint space may be narrow or absent

Loss of cortex or erosions of the articulating surfaces of the condyle or temporal component are characteristics of this disease

D/D:

- Erosive appearance inflammatory arthritides (rheumatoid arthritis)

- Proliferative appearance with extensive osteophyte formation benign tumor osteoma or osteochondroma

Treatment:

- Relieving joint stress (e.g. Splint therapy)

- relieving secondary inflammation with anti-inflammatory drugs

- Increasing joint mobility and function physiotherapy

3- Rheumatoid Arthritis:

- Synovial membrane inflammation

- Patients with TMJ involvement complain of swelling, pain, tenderness, stiffness on opening, limited range or motion, and crepitus

- Radiographic Features:

- Osteopenia (decreased density) of the condyle and temporal component

- erosion of anterior and posterior condylar surfaces

if erosion is severe condylar head is destroyed

D/D: severe DJD and psoriatic arthritis and osteopenia

Treatment:

- pain relief (analgesics)

- anti inflammatory drugs

- physiotherapy

- surgery (joint replacement)

4- Juvenile Arthritis:

- Inflammatory disease that is characterized by chronic, intermittent synovial inflammation

- results in: synovial hypertrophy, joint effusion, and swollen, painful joints

-pain and tenderness of affected joint or joints

- can be asymptomatic

- unilateral is common

- facial appearance known as “bird face”

- possible mandibular asymmetry if one side is more severely affected

Radiographic features:

- Osteopenia (decreased density) maybe only an initial radiographic finding

- Impaired mandibular growth

- Severe cases: only pencil shaped small condyle remains

- Abnormal disk shape is often observed in patients with TMJ involvement

Psoriatic Arthritis and

Akylosing Spondylitis

Septic Arthritis: Infection and inflammation of a joint that can result in joint destruction

- Affects any age

- No sex predilection

- Occurs unilaterally

- Redness and swelling over joint

- Trismus

- Severe pain on opening

- Inability to occlude the teeth

- Large, tender cervical lymph nodes

- Fever and malaise


- No radiographic signs may be present in early stages of the disease

- Osteopenic (radiolucent) changes of the joint components and mandibular ramus may be evident (7-10 days after onset of clinical symptoms)

- Osseous ankylosis may occur after infection subsides

D/D: radiographic changes caused by septic arthritis may mimic those of severe DJD or RA

Treatment:

- Antimicrobial therapy

- Drainage of effusion and joint rest

- Physiotherapy

Articular Loose Bodies

- Radiopacities of varying origin located in the joint synoviom, within the capsule in the joint spaces, or outside in soft tissue

1- Synovial Chondromatosis:

- Uncommon disorder characterized by metaplastic formation of multiple cartilaginous and osteocartilaginous nodules within connective tissue of the synovial membrane of joint

- Asymptomatic

- May complain of preauricular swelling, pain, and decreased range of motion

- Some patients have crepitus or other joint noises


- Osseous components may appear normal or may exhibit osseous changes similar to those in DJD

- Sclerosis of glenoid fossa and condyle may be seen (chronic bone reaction to an active lesion)

- MRI may be useful in defining the tissue planes between the synovial chondromatosis and surrounding soft tissue

* D/D: DJD with joint mice or chondrosarcoma or osteosarcoma

* Treatment: Arthroscopic or open joint surgery remove loose bodies and resection of abnormal synovial tissue

2- Chondrocalcinosis:

- Characterized by acute or chronic synovitis and precipitation of calcium pyrophosphate dihydrate crystals in the joint space

- Most commonly affected joints are knee, wrist, shoulder, and elbow

- TMJ involvement uncommon

- Unilaterally and more common in males

- Asymptomatic or complaints of pain and joint swellings


- May simulate synovial chondromatosis

- Bone erosions and severe increase in condylar bone density

- Erosions of the glenoid fossa may be present (detected with CT)

- Soft tissue swelling and edema of the surrounding muscles may be seen with MRI

* D/D: DJD with joint mince or chondrosarcoma or osteosarcoma

* Treatment:

- Surgical removal of crystalline deposits

- Steroids, aspirin, and non steroidal anti inflammatory agents may provide relief

Trauma

1- Effusion:

- Influx of fluid into the joint as a result of trauma (hemorrhage or inflammation)

- Swelling over affected joint

- Pain in TMJ, preauricular region, and limited range of motion


- Commonly seen in conjunction with internal derangements

- Joint space is widened

* D/D: septic arthritis

* Treatment:

- Anti-inflammatory drugs

- Surgical drainage

2- Dislocation:

- Abnormal positioning of the condyle out of the mandibular fossa but within the joint capsule

- Unable to close mandible to maximal intercuspation

* Radiographic Features:

- In bilateral cases, both condyles are located anterior and superior to summits of articular eminentia

* Treatment:

- Manual manipulation to reduce the dislocation

- Surgery in the case of fracture dislocation

3- Fracture:

- Usually occur at condylar neck and often are accompanied by dislocation of the condylar head

- Unilateral fractures more common

- May be accompanied by parasymphyseal or mandibular body fracture on contralateral side

- Swelling over TMJ

- Limited range of motion

Radiographic features:

- Radiolucent line limited to the outline of the neck is visible

- If bone fragments overlap, an area of increase in radiopacity may be seen

* D/D: Town’s view panorama is taken to view fractures

* Treatment: Reduced surgically

4- Neonatal Fracture:

- Use of forceps during delivery of neonates may result in fracture and displacement of the rudimentary condyle

- Severe mandibular hypoplasia

* D/D: Developmental hypoplasia

* Treatment: Combination of orthodontic and orthognathic surgery

5- Akylosis:

- Condition in which condylar movement is limited by a mechanical problem in the joint or by a cause not related to joint components

- Restricted jaw opening or limited jaw opening


- In fibrous ankylosis articulating surfaces are usually irregular because of erosions

- In bony ankylosis joint space may be partly or completely obliterated by the osseous bridge

- Coronal CT images are the best

to evaluate ankylosis

* D/D: Condylar Tumor

* Treatment:

- Surgical removal of osseous bridge

- Creation of pseudoarthrosis

Tumors

- Intrinsic or extrinsic

- Intrinsic develop in condyle, temporal bone or coronoid process

- Extrinsic tumor may affect the morphology, structure and function of the joint without invading the joint itself

1- Benign Tumors:

- Osteoma, osteochondroma, Langerhans histocytosis and osteoblastomas

- Chondroblastomas, fibromyxomas, benign giant cell lesions and anneurysmal bone cysts also occur

- Benign tumors and cysts of the mandible may involve the entire ramus and condyle

- Grow slowly

- TMJ swelling

- Pain and decrease in range of motion

- Tumors of coronoid process are painless but may complain of progressive limitation of motion


- Condylar tumors condylar enlargement with irregular outline

- Osteoma and osteochondroma appear as abnormal, pedunculated mass attached to the condyle

* D/D: Condylar neoplasms may simulate condylar hyperplasia because of condylar enlargement although it might be irregular in appearance

* Treatment: Surgical excision of tumor and occasionally excision of condylar head or coronoid process

2- Malignant Tumors:

A- Primary (rare): - Intrinsic

- Extrinsic

Intrinsic: Chondrosarcoma

Osteogenic sarcoma

Senovial sarcoma

Fibrosarcoma

Extrinsic: Direct extension of adjacent parotid salivary gland malignancies

B- Metastatic (more common)

- May be asymptomatic or patients may have symptoms of TMJ dysfunction (pain, limited mandibular opening, mandibular deviation and swelling)


- Variant degree of bone destruction with ill defined, irregular margins

- CT modality of choice

- MRI useful for displaying extent of involvement into surrounding tissues

* D/D: Osseous destruction of bone seen in severe DJD

* Treatment:

- Wide surgical removal of tumor

- May include radiotherapy and chemotherapy

Thank you

radiographic imaging of tmj

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