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The Tempromandibular Joint (TMJ)
By: Nour-Eldin A. Nour-Eldin Mohammed
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Normal Anatomy Mandibular condyle (head) Glenoid fossa
Articular tubercle (eminence)
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Posterior band of articular disc
Anterior band of articular disc Mandibular condyle (head) Lateral pterygoid muscle raphe Lower head of lateral pterygoid muscle Posterior disc attachment
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Mandibular condyle (head)
Articular disc
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MRI and autopsy sections: upper row oblique sagittal MRI, asymptomatic volunteer: left lateral, middle medial, right opened mouth
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Internal Derangements
General orthopedic term implying a mechanical fault that interferes with the smooth action of a joint The most common internal derangement is disc displacement Clinical Features Clicking sounds from joint(s) Restricted or normal mouth opening capacity Deviation on opening Pain
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Internal Derangements
Imaging Features Anterior disc displacement: posterior band of the disc located anterior to the superior portion of the condyle at closed mouth on oblique sagittal images Disc may have normal (biconcave) or deformed morphology In opened mouth position disc may be in a normal position (“with reduction”) or continue to be displaced (“without reduction”)
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Partial anterior disc displacement at baseline
lateral sections central sections open-mouth
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Complete anterior disc displacement
medial section Autopsy Open-mouth MRI
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Lateral disc displacement and normal bone
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Medial disc displacement
coronal MRI Oblique coronal MRI
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Posterior disc displacement
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Osteoarthritis Definition
Non-inflammatory focal degenerative disorder of synovial joints, primarily affecting articular cartilage and sub-condylar bone; initiated by deterioration of articular soft-tissue cover and exposure of bone. Clinical Features Crepitation sounds from joint(s) Restricted or normal mouth opening capacity Pain or no pain from joint areas and/or of mastication muscles Occasionally, joints may show inflammatory signs Women more frequent than men
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anteriorly displaced and deformed, degenerated disc and irregular cortical outline with osteophytosis and sclerosis of condyle .
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Advanced osteoarthritis and anterior disc displacement, with joint effusion
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Bone Marrow Abnormalities
Definition Bone marrow edema: serum proteins within marrow interstitium surrounded by normal hematopoietic marrow. Osteonecrosis: complete loss of hematopoietic marrow.
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Imaging Features Abnormal signal on T2-weighted image from condyle marrow: increased signal indicates marrow edema; reduced signal indicates marrow sclerosis or fibrosis Combination of marrow edema signal and marrow sclerosis signal in condyle most reliable sign for histologic diagnosis of osteonecrosis Marrow sclerosis signal may indicate advanced osteoarthritis without osteonecrosis, or osteonecrosis
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Arthritides Definition
Inflammation of synovial membrane characterized by edema, cellular accumulation, and synovial proliferation (villous formation). Clinical Features Swelling of joint area, not frequently seen in TMJ Pain (in active disease) from joints Restricted mouth opening capacity Morning stiffness, in particular stiff neck Dental occlusion problems; “my bite doesn’t fit” Crepitation due to secondary osteoarthritis
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Rheumatoid arthritis. After 1 year
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Rheumatoid arthritis. A MRI shows completely destroyed disc, replaced by fibrous or vascular pannus and cortical punched-out erosion (arrow) with sclerosis in condyle.
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Psoriatic arthropathy
Psoriatic arthropathy. Oblique coronal and oblique sagittal CT images show punched-out erosion in lateral part of condyle (arrow). Psoriatic arthropathy. MRI shows contrast enhancement within bone erosion and in joint space, consistent with thickened synovium/pannus formation. Openmouth MRI shows reduced condylar translation but normally located disc (and normal bone in this section)
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Inflammatory arthritis
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Ankyloses Definition Fibrous or bony union between joint components.
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Growth Disturbances (Anomalies)
Definition Abnormal growth of mandibular condyle; overgrowth, undergrowth, or bifid appearance.
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Condylar hypoplasia and facial asymmetry
Normal TMJ
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Bifid condyle.
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Inflammatory or Tumor-like Conditions
Calcium Pyrophosphate Dehydrate Crystal Deposition Disease (Pseudogout)
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Benign Tumors Synovial Chondromatosis
Benign tumor characterized by cartilaginous metaplasia of synovial membrane, usually in knee, producing small nodules of cartilage, which essentially separate from membrane to become loose bodies that may ossify.
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Synovial Chondromatosis
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Osteochondroma Definition
Benign tumor characterized by normal bone and cartilage, near growth zones.
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Osteoma
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Osteosarcoma mandible; 18-yearold female
Malignant Tumors Osteosarcoma mandible; 18-yearold female
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Malignant tumor, mandible; 70- year-old male with metastasis from lung cancer
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Thank you
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