Tempero-Mandibular Disorders Dr Deepa Abichandani

TM Joint : connects the mandible to the skull and regulates mandibular movement is a bi-condylar joint The movable round upper end of the lower jaw is called the condyle and the socket is called the articular fossa, with a disc made of fibrocartilage that acts as a cushion to absorb stress and allows the condyle to move easily when the mouth opens and closes. Anatomy

Anatomy

The disc divides the joint cavity into two compartments (superior and inferior), filled with synovial fluid which provides lubrication and nutrition to the joint structures. The disc distributes the joint stresses over broader area thereby reducing the chances of concentration of the contact stresses at one point in the joint, preventing bone-on-bone contact and the possible higher wear of the condylar head and the articular fossa. Ligaments include -- Temporomandibular ligament, Stylomandibular ligament & Sphenomandibular ligament Anatomy

Anatomy Muscles include – Temporalis muscle  elevates the mandible. Masseter muscle  closes the mouth and is the main muscle used in mastication. Medial & Lateral Pterygoid muscles. The most important functions of the TMJ are mastication and speech. Anatomy

Biomechanics

The most common TMJ disorders are pain dysfunction syndrome, internal derangement, arthritis, and traumas. TMD is seen most commonly in people between the ages of 20 and 40 years, and occurs more often in women than in men. TMJ Disorders

TMJ Disorders Internal Derangement Of Disc : Almost 70% of TMD patients have disc displacement. Coordinated movement of condyle and disc is essential to maintain the integrity of the disc. Disc displacement  most common TMJ arthropathy and is defined as an abnormal relationship between the articular disc and condyle. As the disc is forced out of the correct position there is often bone on bone contact which creates additional wear and tear on the joint, and often causes the TMD to worsen. Disc displacement  a popping sound, when the disc is first forced out of alignment as the mouth opens up and then again as the disc is forced back into place as the mouth is closed, which is regarded as an initial symptom of the temporoman- dibular joint internal derangement TMJ Disorders

TMJ Disorders Internal Derangement Of Disc : The anterior disc displacement has different degrees of severity. Wilkes developed staging classifications for the TMJ related internal derangement, or disc displacement These stages were defined based on clinical or radiological findings, or based on the anatomic pathology of the jaw. The disc displacement induces the change of stress distribution in the disc and the increase of frictional coefficients between articular surfaces, resulting in the secondary tissue damage. The internal derangement frequently precedes the onset of TMJ osteoarthritis. TMJ Disorders

Wilkes Classification of Derangement STAGE CLINICAL IMAGING SURGICAL I] EARLY Painless Clicking No restricted motion Slightly forward disc, with reduction* Normal osseous contours Normal disc form Slight anterior displacement Passive incordination (clicking) II] EARLY / INTERMEDIATE Frequent pain Joint tenderness, headaches Locking Restricted motion Painful chewing Slightly forward disc, reducing Early disc deformity Anterior disc displacement Thickened disc Wilkes Classification of Derangement

Wilkes Classification of Derangement STAGE CLINICAL IMAGING SURGICAL III] INTERMEDIATE Frequent pain Jt tenderness, headaches Locking Restricted motion Painful chewing Anterior disc displacement, reducing early progressing to non-reducing*late Moderate to marked disc thickening Normal osseuos contours Disc deformed & displaced Variable adhesions No bone changes IV] INTERMEDIATE/ LATE Chronic pain, headache Ant disc displacement, non –reducing Marked disc thickening Abnormal bone cotours Degenerative remodeling of bony surfaces Osteophytes Adhesions, deformed disc without perforation Wilkes Classification of Derangement

Wilkes Classification of Derangement STAGE CLINICAL IMAGING SURGICAL V] LATE Variable pain Joint crepitus Painful function Ant disc displacement, non-reducing with perforation and gross disc deformity Degenerative bone changes Gross degenerative changes of disc, and hard tissue; Perforation Multiple adhesions * -- refers to disc position in relation to the condyle when the mouth is open Wilkes Classification of Derangement

TMJ Disorders Osteoarthritis of TMJ : OA is a degenerative disease of movable joints. In the TMJ, the disease is characterized by deterioration of the articular cartilage, disc, synovium, and subchondral bone, and with rare exception, disc displacement. MRI shows bone marrow changes in the condyle. Histopathological evaluation of these marrow changes suggest they represent osteonecrosis Secondary inflammatory change  from tissue damage in the joint, with inflammatory mediators (neuropeptides, cytokines, serotonin, free radicals) being isolated from fluid in symptomatic joints with ID and OA which play a role in producing pain. TMJ Disorders

Signs & Symptoms The typical signs and symptoms of ID and OA are pain in the joint (preauricular region) headaches behind and around the eyes, and pain radiating from the joint to the temple, ears, side of neck and upper shoulder. The pain is typically aggravated by wide opening, chewing or other joint activities, such as clenching and bruxism. There often is clicking, popping or “locking” because of disc interference, which results in reflex masticatory muscle spasm. The joint, muscles of mastication, sternocleidomastoid muscle and trapezius muscle are often tender to palpation Signs & Symptoms

Assessment Examination : Palpate the joint by placing the fingertips in the preauricular region just in front of the tragus of the ear. The patient is then asked to open their mouth and the fingertip will fall into the depression left by the translating condyle. Palpate the head, neck and masticatory muscles for areas of tenderness, Joint clicks or grating sounds on jaw movement may be palpable, or may be heard with a stethoscope over the preauricular area. Assess mandibular movement: Measure the distance of painless vertical mouth opening, using inter-incisal distance (normal range 42-55 mm). Observe the line of the vertical jaw opening: straight or deviating, smooth or jerky. Examine lateral movements and jaw protrusion. Assess other orofacial structures - salivary glands, oral cavity, dentition, ears and cranial nerves. Assessment

Assessment Investigations : No tests may be needed in straightforward cases. Possible investigations are: Blood tests : ESR, CRP for inflammation. Plain radiographs - show gross bony pathology such as degeneration or trauma. CT or MRI scan of the joint. MRI scan shows the soft tissues and intra-articular disc well. Ultrasound - this is a useful alternative imaging technique for monitoring TMJ disorders. Ultrasound - this is a useful alternative imaging technique for monitoring TMJ disorders. Diagnostic nerve block. Arthroscopy. Assessment

TM – Joint & Related Musculoskeletal Disorders Intra-articular (Intracapsular) Pathology --- A. Articular Disc : Displacement 2. Deformity 3. Adhesions 4. Degeneration 5. Injury 6. Perforation 7. Anomalous development B. Disc Attachments : Inflammation 2. Injury (laceration, hematoma, contusion) 3. Perforation 4. Fibrosis 5. Adhesions TM – Joint & Related Musculoskeletal Disorders

TM – Joint & Related Musculoskeletal Disorders C. Synovium : Inflammation/effusion Injury Adhesions Synovial hypertrophy/ hyperplasia Granulomatous inflammation Infection Arthritides (rheumatoid, degenerative) Synovial chondromatosis Neoplasia D. Articular Fibrocartilage : 1. Hypertrophy/hyperplasia 2. Degeneration (chondromalacia) -- a. Fissuring b. Fibrillation c. Blistering d. Erosion TM – Joint & Related Musculoskeletal Disorders

TM – Joint & Related Musculoskeletal Disorders E. Mandibular condyle and glenoid fossa (see also Musculoskeletal) Osteoarthritis (osteoarthrosis, degenerative joint disease) 1. Avascular necrosis (osteonecrosis) 2. Resorption 3. Hypertrophy 4. Fibrous and bony ankylosis 5. Implant arthropathy 6. Fracture/dislocations II. Extra-articular (Extracapsular Pathology) Musculoskeletal Bone (temporal, mandible, styloid) a. Anomalous development (hypoplasia, hypertrophy, malformation, ankylosis) b. Fracture c. Metabolic disease d. Systemic inflammatory disease (connective tissue/arthritides) e. Infection f. Dysplasias g. Neoplasia 2. Masticatory muscles and tendons a. Anomalous development b. Injury c. Inflammation d. Hypertrophy e. Atrophy f. Fibrosis, contracture g. Metabolic disease h. Infection i. Dysplasias j. Neoplasia k. Fibromyalgia B. Central nervous system/peripheral nervous system 1. Reflex sympathetic dystrophy TM – Joint & Related Musculoskeletal Disorders