TEMPOROMANDIBULAR JOINTTMJ is a ginglymo-diarthroidal joint that is freely mobile with superiorand inferior joint spaces separated by articular disc.
Radiographic anatomy Extreme aspects of condyle – medial & lateral poles Long axis of condyle is slightly rotated on the condylar neck such that the medial pole is angled posteriorly- angle of 15 to 33 degrees with the sagittal plane. Two condylar axes typically intersect near the anterior border of the foramen magnum- submentovertex projection
Complete calcification of TMJ-20 yrs No cortical border in children-radiograph Mandibular fossa & articular eminence-4 yrs- mature shape Pneumatization-sometimes Radiographic joint space-radiolucent area between the condyle and temporal component
CONVENTIONAL RADIOGRAPHYOrthopantomogram: Conventional OPG machine orients the x ray beam obliquely through the condyle. Limited view of the fossa condyle relationship.
The patient’s head is displaced forward/ the alignment of the source is altered so that the central beam is oriented along the long axis of the condyle. Condyles - gross osseous changes, extensive erosions, growths or fractures No information about condylar position or function(Mandible is partly opened and protruded when thisRadiograph is exposed)
Dental panoramic tomographIndications- TMJ dysfunction syndrome Disease within joint Pathology-condylar heads Fracture of condylar head & neck Condylar hypo/hyperplasia
Advanced high condylar panoramic radiography Sagittal (lateral) plane ->several image slices Closed (maximal intercuspation) position & in maximal open position Condylar long axis with respect to the midsagittal plane –submentovertex patients head is rotated to an angle, permitting alignment of image slices perpendicular to the condylar long axis.
A B CCorrected lateral (sagittal) tomograms. A represents a lateral image slice, B represents a medial image slice of the same joint. Condyle appears centered in the lateral image and retruded in the medial image. C, Open view showing the degree of condyle translation during mandibular opening.
Minimizes geometric distortion of joint- condylar position. Corrected tomographic technique-not available 20-degree head rotation toward the side of interest is superior to image slices parallel to the midsagittal plane. Bite block
Coronal tomographs Maximal open or protruded position Condyle to the summit of the articular eminence Free of superimposition of the posterior slope of eminence. Entire condylar head is visible in the mediolateral plane
CONVENTIONAL RADIOGRAPHS TRANSCRANIAL VIEW INDICATION AREA OF JOINT SEEN TMJ pain Lateral aspect of: dysfunction Glenoid fossa syndrome Internal Articular eminence derangement Joint space Range of movement in joints Condylar head
Film position: flat against patients ear Centered over TM joint of interest Against facial skin parallel to sagittal plane Position of patient: head adjusted so sagittal plane is vertical & ala tragus line parallel to floor View :3 positions-open, close, rest mouth
Central ray A) Postauricular/ Lindblom Technique-1/2 inch behind and 2 inch above auditory meatus-central ray should be directed posteriorly so it passes along long axis of condyle. B) Grewcock approach-central ray passes through a point 2 inches above ext. auditory meatus. C) Gill’s approach- ½ inch anterior and 2 inch above EAM
Central ray aimed downwards at 25 degree to the horizontal, across the cranium, centering through TMJ of interest Closed view- size of joint space, position of head of condyle, shape & condition of glenoid fossa & articular eminence Open view- range & type of movement Comparison of both sidesDisadvantages : Superimposition of ipsilateral petrous ridge over the condylar neck
Transcranial projections of the left TMJ. degree of translatory movement between the closed view (A) and the open view
TRANSPHARYNGEAL VIEW/Infracranial/McQueen DellINDICATION AREA OF JOINT SEENTmj pain dysfunction Lateral view:syndrome Condylar head & neckOsteoarthritis &rheumatoid arthritis Articular surfacePathology-condylarhead-cyst & tumorFracture of neck &condyle
Film placement-patient holds the cassette flat against patients ear Centered over TM joint of interest Against facial skin parallel to sagittal plane ½ inch anterior to EAMPosition of patient- occlusal plane parallel to transverse axis of film-soft parts are in a line with nasopharynx and joint
Patient instructed to inhale slowly through nose, filling of nasopharynx with air Open mouth-condyles move away from base of skull and mandibular notch is enlarged on opp side. Central ray- directed from opp side cranially at angle(-5 to -10 degrees) Beneath the zygomatic arch, through sigmoid notch posteriorly across pharynx at the condyle Comparison of both condylar heads
Parma modification Lead lined open ended cone is removed and tube head is brought closer to skin surface producing magnification of structure reducing superimposition
TRANSORBITAL (ZIMMER PROJECTION)INDICATION AREA OF JOINT SEENTrauma Ant view of TMJFracture cases Medial displacement of fractured condyle Fracture of neck of condyle
Film position-behind patients head at an angle of 45 degree to sagittal pane Position of patient--sagittal pane vertical-Canthomeatal line should be 10 degree to the horizontal with head tipped downwards Central ray--tube head-front of patients face-directed to joint of interest at an angle of +20 degrees to strike cassette at right angles
Point of entry may be taken as-- Pupil of the same eye-asking patient to look straight ahead- Medial canthus of the same eye- Disadvantage : if the patient cannot open wide, areas of the joint articulating surfaces will be obscured because of mutual superimposition
Reverse towne’sINDICATION AREAS OF JOINT SEENArticular surface of Posterior view of bothcondyles and disease condylar head and neckwithin jointFracture of condylarhead & neck,intracapsular fractureCondylarhypo/hyperplasia
Film position-cassette placed perpendicular to the floor Long axis of cassette placed vertically Position of patient--sagittal plane vertical & perpendicular to film-lips are centered on the film-only forehead should touch the film-mouth wide open-angle of negative 30 degrees to film Central ray-directed midsagittal plane at the level of mandible and perpendicular to film
Forehead –nose position Appreciation of condyle on left side REVERSE TOWNE’S (Eric Whaites)
Towne’s view/anteroposterior view Observe occipital area of skull Neck of condylar process Film position-cassette perpendicular to floor, long axis-vertically Position of patient- back of patients head touching film. canthomeatal line perpendicular to film Central ray-30 degree to canthomeatal line & passes it at a point b/n external auditory canals
ULTRASONOGRAPHYUltrasonography was described to be analternative method in the imaging of the TMJby Stefanoff et al. (1992).High resolution ultrasonography was used toshow satisfying results in further studies byEmshoff et al. (2002) and Jank et al. (2002).
MARCELLO MELIS et al. Use of ultrasonography for the diagnosis of temporomandibular joint disorders: A review . Am J Dent2007;20:73-78 Noninvasive and inexpensive Advantages Disc displacement and joint effusion Scarce accessibility of the medial part of the TMJ structures Disadvant ages Need for trained and calibrated operators
Positioning of the transducer and consequent visualization of thetemporomandibular joint (TMJ). A. Horizontal positioning,transverse image of the TMJ. B. Vertical positioning,coronal/sagittal image of the TMJ (depending on the angulation ofthe transducer).
TMJ ARTHROGRAPHY Norgaard (1940)Indications: Position and function of disk -pain and dysfunction-long standing History of locking-persistent Perforations of the disk and retrodiskal tissue. Joint dynamics Disc displacement-ant/anteromedial
Therapeutic : To delineate loose bodies in the joint spaces Diagnostic aspiration of joint fluid. Intraarticular injections of steroids Contraindications: Infections in the preauricular region. Patients allergic to contrast media. Patients with bleeding disorders and on anticoagulant therapy
Disk is anteriorly positioned and thickenedTechniquesSingle contrast – lower compartment arthrography is most commonly doneDouble contrast – contrast medium into the lower compartment and injection of air into the upper compartment.
STEPS Contrast media – non ionic agents such as iopamidol-370,iodohexol-350 Fluoroscopy aids in accurate positioning of needle Primary record-video-allows imaging of joint compartments as they move Only lateral parts seen
Medial aspect of joint-thin section multidirectional hypocycloidal tomography 5-6 slides ,2-3 mm apart, patient mouth open and closed If further info-contrast –upper joint space- repeat investigation
ARTHROSCOPYContraindicationsAbsolute Bony ankylosis. Advanced resorption of the glenoid fossa. Infection around the joint area. Malignant tumors.Relative Patients at increased risk of hemorrhage. Patients at increased risk for infection.
Arthroscopes:Types Classic thin lens Rod lens Coherent bundle Graded refractory index systemField of vision is increased by rotating the instrument.
EQUIPMENTArthroscopic sheath : Fits on the arthroscope- protects the tip. Used for irrigation , suction of any loose fragment. Light source : xenon arc illuminator. T.V camera and video. Biopsy forceps
TECHNIQUEThree primary approaches to the upper compartment Lateral posterior Lateral anterior End aural
Areas visualized Loss of well defined boundary b/w PDA and posterior part of the disk seen in degenerative changes : Osteoarthritis elongation of the PDA Medial capsule
Complications Vascular injury Extravasation of irrigation fluid into the surrounding tissue Broken instruments in the joint Intracranial damage Infection Nerve injury
Computed Tomography (CT) Three-dimensional shape and internal structure of the osseous components Surrounding soft tissue Both axial & coronal images Reformat images in sagittal plane Not diagnostic for disk
Indications Extent of ankylosis neoplasms-bone involvement Complex fractures Complications -polytetrafluoroethylene or silicon sheet implants -erosions into the middle cranial fossa Heterotopic bone growth
DIRECT SAGITTAL CT SCANS 3 scans/joint-closed, half, open- 2mm slice thickness Neck bent- 45 to 55 degree so thatthe plane of ramus is parallel to the imaging plane
Panoramic radiograph displaying duplication of both condyles. Coronal computed tomography GUNDUZ, K.; AVSEVER, H. & KARACAYLI, U. Bilateral bifid condylar process. Int. J. Morphol., 28(3):941-944, 2010.
MAGNETIC RESONSNCE IMAGING (MRI) Magnetic field and radiofrequency pulses Tissue with greater water content emit a higher signal Bilateral dual surface coils- 0.5 to 2 tesla-Improve image resolutionOblique sagittal/oblique coronal scans with t1, t2Closed mouth, partially open and fully open positions
images in the sagittal and coronal planes without repositioning the patient T1-weighted images best –osseous & diskal tissues T2-weighted images-inflammation and joint effusion. Motion MRI studies-during opening and closing the patient open in a series of stepped distances and using rapid image acquisition. ("fast scan ")
Disk is of low signal intensity (dark grey or black)and can be distinguished from surrounding tissuethat has high signal intensity.Posterior disk attachment (PDA) shows higherthan the disk and the junction between theposterior band of the disk and PDA is distinct.Medial disk displacements-best seen
MRI of a normal TMJ. A, Closed view showing the condyle and temporal component. The biconcave disk is located with its posterior band (arrow) over the condyle.B. Coronal image showing the osseous components and disk(arrows) superior to the condyle.
This sagittal MR image showsanterior disk displacement in the closed mouth position. Disc is deformed
anteriorly displaced and deformed, degenerated disc and irregular cortical outline
Advantages of CT Advantages of MRI Direct delineation of bony structures-surgical anatomy Soft tissues-esp disk and Reconstruction in all planes its association Some soft tissues-lateral Information in short pterygoid muscle acquisition time 3-D images from any angle Disadvantages- Disadvatages--high radiation exposure -expensive-soft tissues cant be -claustophobia appreciated
BONE SCINTIGRAPHY Sensitive technique Bone and joint pathology Intravenous injection of tracer dose of radionuclide- technetium methylene diphosphonate. Planar and tomographic images are obtained in all planes. Indication-to rule out tumors, condylar hypoplasia,internal derangement
Advantages of bone scintigraphy : Bone changes are demonstrated before they are depicted by radiographic examn up to 6 to 12 months earlier in neoplastic involvement. Up to 2 weeks earlier in bone infection.Disadvantage Lack of specificity. Radionuclide imaging of a patient with condylar hyperplasia of the left TMJ
CONCLUSION Complex joint Multiple pathologies Superimposition and clear view-correct positioning Proper diagnosis and treatment plan
References White & Pharoah Eric whaites Karjodkar R. Gray.Risk management in clinical practice. Part 8. Temporomandibular disorders. British Dental Journal 209, 433 - 449 (2010)