14 - TMJ

Question 1

Condylar Hyperplasia Classification

Answer 1

Obwegeser and Makek 1986

• Hemimandibular Elongation
• Hemimandibular Hyperplasia
• Combined

Nitzan 2008

• Vertical - 31%
• Horizontal - 52%
• Combined - 17%

Wolford 2014

• Type I
  
  • 1A - Class III - Bilateral growth beyong normal for age
  • 1B - HME - Unilateral
• Type 2 - Enlarging Osteochondroma
  
  • 2A - Growth confined to condylar neck
  • 2B - Exophytic growth laterally as well
• Type 3 - Other benign tumors (Can be of non osteo or cartilaginous origin)
• Type 4 - Other malignant tumors

Question 2

Idiopathic Condylar Resorption Pathophysiology Theories

Answer 2

Wolford 1999

• Estrogen mediated dysfunction of the condyle
  • Estrogen receptors present in TMJ in primate studies
    Estrogen known to mediate cartilage and bone metabolism in females
• Disease Progression
  • Low estrogen leads to hyperplasia of synovial tissues
    Leads to production of destructive substrates leading to weakening of ligaments
    Destabilization of articular disc
    Disc becomes anteriorly displaced
    Disc dysfunction -> osteoarthritis
    Hyperplastic tissue continue to grow and surround the condylar head leading to resorptive process
• Gunson & Arnett 2012
  • Generation of free radicals
    Metabolic & Homeostatic imbalance
  • Disease Progression
    • Generation of free radicals
      Hypoxia reperfusion mechanism
      Homolytic fission of molecules
    • Imbalance in bone metabolism
      Resorption > Deposition
      • Gender, Age, Systemic factors, Hormonal factors
    • Inflammatory driven resorption requires
      Cytokines
      MMP
      COX Pathway

Question 3

Joint Hypermobility Treatment

Answer 3

Conservative Management

• Limit mout opening
• Cough or yawn with palm under chin
• Cut food up into bite size pieces

Surgical Management

• Scarification
  
  • Autologous blood - 80% at 12 months (can require up to 3 procedures)
  • 50% Dextrose - 91% at 18 months
  • OK-432
  • Electrothermal capsulorraphy
  • Arthroscopic approach with laser or electrocautery - 82% at 27 months
• Limit translational movements of the joint
  
  • Intermaxillary fixation
  • Botox
    
    • Lateral pterygoid muscle - 80% at 6 months
    • Indicated in Neuromuscular conditions
  • Disc plication
    
    • Wolford 1993
    • Disc plicated to the posterior of the condylar head
  • Eminoplasty +/- block graft
    
    • Eminoplasty - LeClerc 1943
      
      • Gleno-temporal osteotomy
  • Dautrey’s procedure - Dautrey 1975
    
    • Zygomatic arch downfracture
• Removal of obstruction to joint relocation
  
  • Eminectomy
    
    • Myrhaug 1951
    • 100% 5 years
    • Contraindicated in pneumatisation of Articular eminence
• Case reports
  
  • Total joint replacement
    • Indicated if there is end stage concomitant joint pathology

Allows shaping of the condylar head and glenoid fossa subunit

* Bimaxillary osteotomy
    * Severe Class II dolichofacial with high mandibular plane angle
    * Flattens occlusal plane with auto-rotation
    * Allows the condylar head to sit in a more favourable position

Question 4

Dislocation Classification

Answer 4

• Subluxation
  
  • Transient partial dislocation of the TMJ that are usually self resolving
• Acute dislocation
  
  • Dislocation caused by precipitant requiring manual reduction
• Chronic dislocation
  
  • Dislocation greater than 3 weeks
• Recurrent dislocation
  
  • Recurrent episodes of acute dislocation

Question 5

Hypermobility Theories and Workup

Answer 5

Aetiology not well understood
Theories include:

• Joint and capsule laxity
• Anatomical variation in TMJ and Skull base anatomy
• Medical conditions
  
  • Connective tissue disorders
  • Neuromuscular conditions (eg - Parkinson’s Disease)
    
    • Dystonia of muscles

Work up

• History
  
  • Hx of trauma or precipitating event
  • Hx of dislocations
• Investigations
  
  • Plain films
    
    • Condylar head anterior to articular eminence
  • CT
    
    • Bony anatomical variation or pathology
  • MRI
    
    • Disc pathology
  • Blood tests
    
    • Connective tissue diseases
    • Ehlers Danlos
    • Inflammatory joint diseases

Question 6

Wilkes Classification

Answer 6

Question 7

Dimitroulis Classification

Answer 7