1. The Tempromandibular Joint (TMJ)
By:
Nour-Eldin A. Nour-Eldin Mohammed

2. Normal Anatomy Mandibular condyle (head) Glenoid fossa
Articular tubercle (eminence)

3. 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

4. Mandibular condyle (head)
Articular disc

5. MRI and autopsy sections: upper row oblique sagittal MRI, asymptomatic volunteer: left lateral, middle medial, right
opened mouth

6. 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

7. 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”)

8. Partial anterior disc displacement at baseline
lateral sections
central sections
open-mouth

9. Complete anterior disc displacement
medial section
Autopsy
Open-mouth MRI

10. Lateral disc displacement and normal bone

11. Medial disc displacement
coronal MRI
Oblique coronal MRI

12. Posterior disc displacement

13. 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

14. anteriorly displaced and deformed, degenerated disc and irregular cortical outline with osteophytosis and sclerosis of condyle .

15. Advanced osteoarthritis and anterior disc displacement, with joint effusion

16. Bone Marrow Abnormalities
Definition
Bone marrow edema: serum proteins within marrow interstitium surrounded by normal hematopoietic marrow.
Osteonecrosis: complete loss of hematopoietic marrow.

17. 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

18. 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

19. Rheumatoid arthritis.
After 1 year

20. Rheumatoid arthritis. A MRI shows completely destroyed disc, replaced by fibrous or vascular pannus and cortical punched-out erosion (arrow) with sclerosis in condyle.

21. 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)

22. Inflammatory arthritis

23. Ankyloses
Definition
Fibrous or bony union between joint components.

24. Growth Disturbances (Anomalies)
Definition
Abnormal growth of mandibular condyle; overgrowth, undergrowth, or bifid appearance.

25. Condylar hypoplasia and facial asymmetry
Normal TMJ

26. Bifid condyle.

27. Inflammatory or Tumor-like Conditions
Calcium Pyrophosphate Dehydrate Crystal
Deposition Disease (Pseudogout)

28. 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.

29. Synovial Chondromatosis

30. Osteochondroma Definition
Benign tumor characterized by normal bone and cartilage, near growth zones.

31. Osteoma

32. Osteosarcoma mandible; 18-yearold female
Malignant Tumors
Osteosarcoma mandible; 18-yearold female

33. Malignant tumor, mandible; 70- year-old male with metastasis from lung cancer

34. Thank you