TEMPOROMANDIBULAR DISORDERS – LECTURE SERIES ANATOMICAL CONSIDERATIONS Clinical A/P Chua Ee Kiam - BDS, MDS, FAMS, Dip (Counselling)

TEMPOROMANDIBULAR DISORDERS – LECTURE SERIES

ANATOMICAL

CONSIDERATIONS

Clinical A/P Chua Ee Kiam - BDS, MDS, FAMS, Dip (Counselling)

Pain

unpleasant sensory & emotional experienceunpleasant sensory & emotional experience

assoc with actual / potential tissue damage, assoc with actual / potential tissue damage,

&/ described in terms of such damage&/ described in terms of such damage

Loeser et al, 2001; Merskey H et al, 1994; Portenoy et al, 1996Loeser et al, 2001; Merskey H et al, 1994; Portenoy et al, 1996

TYPES OF PAIN

1.Nociceptive pain is caused by stimulation of peripheral nerve fibers that respond to noxious stimulation2.Neuropathic pain is caused by damage or disease affecting the central or peripheral nervous system3.Phantom pain is pain from a part of the body that has been lost or from which the brain no longer receives signals

4.Psychogenic pain is pain caused, increased, or prolonged by mental, emotional, or behavioral factors

CHRONIC PAINpersistent / recurrent pain, persistent / recurrent pain,

lasting beyond usual course of lasting beyond usual course of acute Illness/injury,acute Illness/injury,

/>6 mths, />6 mths,

& adversely affecting pat’s well-& adversely affecting pat’s well-beingbeing

Loeser et al, 2001; Merskey H et al, 1994; Portenoy et al, 1996Loeser et al, 2001; Merskey H et al, 1994; Portenoy et al, 1996

• Pain is expressed with gestures and facial expression

Gender differences

• Females are more affected than males• Pain is high when oestrogen is low• Common pain conditions, including migraine and tension-

type headache, facial pain, and abdominal pain, indicate higher prevalence rates in adult women than in adult men.

Gender variations in clinical pain experience- Unruh APain 65:123-167, 1996

IMPORTANCE OF PAIN

1.Makes one withdraw from potentially damaging situations2.Protect a damaged body part while it heals3.Trains one to avoid painful situations in the future

PAIN FACTS

1.Most pain resolves promptly once the painful stimulus is removed2.Some pain persists despite removal of the stimulus3.Sometimes pain arises in the absence of any detectable stimulus, damage or disease

Gate Control Theory was initially proposed in 1965 by Melzack and Wall that a gating mechanism exists in the dorsal horn of the spinal cord. Small nerve fibers (pain receptors) and large nerve fibers (“normal receptors”) synapse on the the substantia gelatinosa and Thalamus (which goes to the brain)

When no input comes in, the SG prevents T from sending signals to the brain (gate is closed)

The Pain Gate Control Theory

NO INPUT –GATE IS CLOSED

Normal somatosensory input happens when there is more large-fiber stimulation. Both the SG and the T are stimulated, but the SG prevents T from sending signals to the brain (gate is closed).


NORMAL INPUT –GATE IS CLOSED

Nociception (pain reception) happens when there is more small-fiber stimulation or only small-fiber stimulation. This inactivates the SG ; T sends signals to the brain informing it of pain (gate is open).

GATE CONTROL THEORY

Chemicals released as a response to the pain stimuli also influence whether the gate is open or closed for the brain to receive the pain signal. This lead to the theory that the pain signals can be interfered with by stimulating the periphery of the pain site.


chemicals

+/-

It is generally recognized that the 'Pain gate' can be shut by stimulating nerves responsible for carrying the touch signal (mechanoreceptors) which enables the relief of pain through massage techniques, rubbing, and also the application of ice packs.


touch-

MUSCLE PAIN (MYALGIA)

Muscle pain can involve more than one muscle and also involve ligaments, tendons, and fascia, the soft tissues that connect muscles, bones, and organs.

Muscle pain also can be a sign of flu infections affecting your whole body and disorders that affect connective tissues throughout the body (SLE).

CAUSES OF MUSCLE PAIN

Injury or trauma

Overuse: using a muscle too much, too soon, too often

Tension or stress

Drugs (Cocaine & Statins for lowering cholesterol)

Infections (Flu, Malaria)

Systemic Disorders (Lupus)

DIAGNOSIS I

1. ARTHRALGIA2. MYALGIA3. SPLINTING

4. TRAUMATIC TRISMUS5. CONTRACTURE6. DISC DISPLACEMENT WITH REDUCTION7. DISC DISPLACEMENT WITHOUT

REDUCTION

DIAGNOSIS II

1. TENDONITIS2. LATERAL CAPSULITIS3. RETRODISCITIS4. SUBLUXATION 5. DISLOCATION 6. OSTEOARTHROSIS7. OSTEOARTHRITIS8. ARTHRITIS

Osteoarthrosis - The cartilage covering bones (articular cartilage) is thinned, eventually completely worn out, resulting in a "bone against bone" joint, reduced motion and pain. Osteoarthritis - the joints exposed to high stress ; pain is experienced

MAIN MUSCLES OF MASTICATION

• Masseter• Temporalis• Medial Pterygoid• Lateral Pterygoid• all innervated by mandibular division of the Trigeminal Nerve

MUSCLES OF MASTICATION

MASSETER

Origin: zygomatic boneAttachment: lateral surface of angle &

ramus of mandibleAction: closes jaw

deep masseter - vertical force

superficial masseter - vertical & slightly anterior force perpendicular to occlusal plane of molars


TEMPORALISOrigin: temporal fossaAttachment: coronoidAction: anterior fibres - close jaw

posterior fibres - retract

DIAGNOSIS

TENDONITIS

complaint of pain on function pain on palpation of tendon attachments anaesthetic block eliminates the pain


MEDIAL PTERYGOID

Origin: pterygoid fossaAttachment: medial surface of angle of mandibleAction: closes jaw and moves mandible to opposite side


LATERAL PTERYGOID

• Superior Pterygoid (LPS)Origin: infratemporal surfaceAttachment: capsule, disc & condylar neck

Action: stays active during power stroke and closing


LATERAL PTERYGOID

• Inferior Pterygoid (LPI)Origin: lateral pterygoid plateAttachment: neck of condyle

Action: protrudes the mandible

stays active during opening

NECK MUSCULATURE

• Sternonucleidomastoid

• Trapezius

• Intrinsic Neck Muscles

MUSCLE PAIN & INJURY

• EMG studiesFranks, 1965, Schwartz, 1968, Stohler, 1985, Yemm, 1971

• ThermographyBerry, 1974, Kopp, 1981

MYALGIA

- subjective complaint of pain in the muscles - tenderness on palpation - if more diffuse - it is called fibromyalgia*

*Fibromyalgia include widespread musculoskeletal pain, severe fatigue, and disturbed sleep.

DIAGNOSIS

SPLINTING guarded jaw opening due to co-contraction of muscles as a means

to avoid pain can be due to reflex splinting due to

behavioural factors

DIAGNOSIS

TRAUMATIC TRISMUS limited range of motion passive stretch - no significant increase can be CNS - induced

DIAGNOSIS

CONTRACTURE chronic resistance of a muscle to passive

stretch a result of fibrosis of supporting tendons,

ligaments and muscle fibers usually caused by trauma can be due to infection irradiation

FORCES OF MASTICATION

1. Force (Brekhus et al, 1941)

Males = 53.6 to 64.4 kg Females = 35.8 to 44.9 kg

2. Range of maxillary force on incisor & molar (Howell & Manly, 1948) 1st molars = 41.3 to 89.8 kg Central Incisors = 13.2 to 23.1 kg

3. Grinding phase (Gibbs et al, 1981)

Closure stroke averaged 26.7 kg

TEMPOROMANDIBULAR JOINT

TMJ is a freely movable joint consisting of the condyle, fossa and a disc that divides into superior and inferior cavities. These cavities are filled with synovial fluid.

Upper compartment - gliding movementsLower compartment - hinge movements

Sensory innervation – Auriculotemporal & masseteric branches of V3 of Trigerminal Nerve From SOTO USA


ARTHRALGIA

complaint of joint pain joint tenderness on palpation


• Condyle• Fossa• Disc• Articular surface• Disc Attachments• Capsule• Accessory Ligaments• Synovial tissues


CONDYLELATERAL VIEW: IRREGULAR CONVEX

LONG AXIS:

right angle to plane of ramus

Long axes of R & L condylar heads meet anterior of foramen magnum at 140 - 160 degrees


CONDYLESIZE : Anterior to posterior = 8 -10mm

Medial to lateral= 15-20mm

FRONTAL VIEW: TENT-SHAPEDLateral pole – is attached TM ligament & lateral part of discMedial pole - is attached only to the disc

CONTOUR: AP - very convex ; ML - gently convex

Top Front


CONDYLE POSITION

Concentricity - 50-65% prevalenceNon-concentricity - posterior (more females)

- anterior (more males)Treatment positions for diagnosis and treatment options- Disc displacements- Reposition therapy- 4/7 position proposed by Gelb


CONDYLE1. Superior and anterior surfaces are articulating areas

2. Form of condylar depends on thickness of CT (Pullinger, Bibb et al; OSOMOP, 1993)

3. Thicker layers thought to be associated with higher loads

4. Condylar asymmetry between R & L are significant in both M & F (Costa RL; Am J Phys Anthropol; 1986)

5. Condylar head is rounder in young than adults


GLENOID OR MANDIBULAR FOSSAanterior wall- squamous temporal posterior wall- tympanic plate thin roof – precludes loading

Functional part is the ARTICULAR FOSSA - entirely of squamous temporal bone and covered by

articular tissue


ARTICULAR FOSSA - entirely of squamous temporal bone and covered by articular tissue

1. Irregular and does not uniformly conform to the shape of the condylar head

2. Variations in form is independent to shape of condylar head (Solberg et al JOR, 1985)

3. Larger mesiolaterally than anteroposteriorly4. Bordered anteriorly by post. slope of articular eminence5. Bordered posteriorly by postglenoid tubercle (this separates

the EAM from TMJ)6. Bordered medially and superiorly by temporal bone


ARTICULAR SURFACES

- are covered with fibrous connective tissue instead of hyaline cartilage

(Fibrous Connective Tissue has high tensile strength. It is found in tendons and ligaments and composed of large amounts of closely packed collagenous fibers)

-thickest at anterior superior of condyle and posterior inferior slope of the eminence

- thickness varies 0.1 to 0.5mm


Cartilage is classified in three types –elastic, hyaline and fibrocartilageUnlike other connective tissues, cartilage does not contain blood vessels hence it heals very slowly

Hyaline cartilage- rich in collagen and proteoglycan- form the smooth articular surface of joints- found in larynx, nose, between ribs and sternum

Elastic cartilage- contains large amounts of elastic fibers (elastin)- stiff yet elastic- found in ear (pinna), epiglottis and Eustachian tube

Fibrocartilage- characterized by a dense network of Type I collagen (most abundant in body)- tough material that provides high tensile strength and support- contains more collagen and less proteoglycan than hyaline cartilage- present in areas most subject to frequent stress like intervetebral discs, symphysis pubis and the attachments of certain tendons and ligaments.

Proteoglycans - (are glycoproteins ) occur in connective tissues of humans.Collagen – main protein in CT in animals


DISCSHAPE: EllipsoidFUNCTION: Support stabilization of condyle against articular eminence

COMPOSITION: Collagen fibersSuperior & inferior fibers - anterior- posterior oriented fibersCentral portion fibers - oriented in all 3 directions of space

POSITION: the posterior band is at the superior crest of the condyle

DISC

The disc functions as articular surfaces against both the temporal bone and the condyles and divides the joint into two compartments

It is bi-concave in structure and attaches to the neck of the condyle medially and laterally (and not to capsule or lateral ligaments

Anterior portion of disc coincides with the insertion of the superior head of the lateral pterygoid

Between the posterior portion and the posterior lamina is the “vascular knee”

Application: Disc surgery to reduce displaced Discs?

DIAGNOSIS

RETRODISCITIS

Inflammation of retrodiscal tissues condyle may be forced posteriorly retrodiscal tissues may swell forcing the

condyle forward - acute malocclusion

with heavy contact on contra-lateral

anterior teeth

DIAGNOSIS

DISC DISPLACEMENT WITH REDUCTION reproducible joint noise pain may be precipitated on jaw movement soft tissue imaging reveal the displaced disc

DIAGNOSIS

DISC DISPLACEMENT WITHOUT REDUCTION marked limited mandibular opening & pain deviation to affected side on opening marked limited laterotrusion to contralateral side no joint noise soft tissue imaging reveal the displaced disc

LOCKED


DISC DISPLACEMENTS

- usually in antero-medial direction- posterior lamina is brought into articulation- conversion into a dense pad by metaplasia- or lead to clicks, locks or degenerative disease


CAPSULE (outer - fibrous membrane)(inner – synovial membrane)

ATTACHMENT• lower-loosely attached to condyle on medial & lateral• upper - lateral tip of glenoid fossa on lateral & sphenoid bone on medial• well organized posterior wall which blends with the disc• thickened laterally to form the TM ligament• anterior aspect of joint - medial 1/2 no capsule• lateral 1/2 loose CT


Lateral ligaments

Major ligament Temporomandibular ligament is thickened lateral part of capsule

Minor ligaments Stylomandibular ligamentSphenomandibular ligament

FUNCTIONThe ligaments define the border movements of the mandible

APPLICATION - Dislocation

Hinge Motion / Rotation

The inferior compartment allows for rotation of the condylar head around with the first 20-25 mm of the opening of the mouth.

Translation

Beyond that, the superior compartment comes into play to allow for translation and maximum opening


SYNOVIAL TISSUES

ATTACHMENT : To disc

SUPERIOR CAVITY (1.2 ml) - anterior and posterior villi folds allow

for translation as much as 2 cm

INFERIOR CAVITY (0.9ml) - villi allows disc to rotate posteriorly as

condyle rotate forward

SYNOVIAL FLUID - lubricant and consist of hyaluronic acid (aids in shock absorption and transportation of nutrients), synovial cells & defence cells

Application 1- Fluid Analysis: Interleukin-1B (Kubota et al, 1977)This cytokine has the potential to initiate events that lead to loss of articular tissue, bone and cartilageApplication 2 – Jaw stuck after clenching


APPLICATION

CAPSULE SURGICAL IMPLICATIONS• Dissection of capsule lateral to condyle leads to the superior cavity

• Dissection of the disc leads to the inferior cavity

• suturing disc to capsule will tense disc to the lateral lip of the glenoid fossa so disc is

deflected to the lateral pole and limit translation

DIAGNOSIS

LATERAL CAPSULITIS

tenderness at lateral pole of condyle usually follows trauma incident continuous pain originating from joint

area

REMODELLING OF THE TEMPOROMANDIBULAR JOINT

i. Progressive remodelling

ii. Regressive remodellingiii. Peripheral remodelling

Osteophytes and sclerosis is part of the remodelling process

Johnson, 1959; Solberg, 1985; Moffet, 1964; Blackwood, 1966

REMODELLING OF THE TEMPOROMANDIBULAR JOINT

1. Progressive remodelling adds new bone due to proliferation of articular cartilage and mineralization

2. Regressive remodelling causes osteoclastic resorption of subchondral bone to be filled by mesenchymal bone and replaced by cartilage, bone or both

3. Peripheral remodelling occurs at margin of articular cartilage

BIOMECHANICS OF THE TEMPOROMANDIBULAR JOINT

BASIC MOVEMENTS

1. Hinge movement –rotation of mandible around transverse axis passing through the centers of condyles(occurs in lower joint compartment between disc and condyle)

2. Sliding movement- bodily movement of mandible in anteroposterior and/or mediolateral direction(upper joint compartment between articular eminence and disc)


INITIAL OPENING PHASE

1-2 Disc rotates posteriorly aided by tension in posterior attachment & inactivty of sup. lateral pterygoid

Disc-condyle moves downwards

3 At mid open, joint is passive and unstressed


FULL OPENING PHASE

3 Gliding of disc is maximum

CLOSING OR POWER STROKE

4 Superior part of lat pterygoid active-tenses disc and cause it to move forward

Disc form s “moving wedge” to ensure full contact between joint components


FULL CLOSURE PHASE

4-1 Disc is rotated forward

Disc is stabilized by posterior attachment

Documents

TEMPOROMANDIBULAR DISORDERS – LECTURE SERIES ANATOMICAL CONSIDERATIONS Clinical A/P Chua Ee Kiam - BDS, MDS, FAMS, Dip (Counselling)