Roentgenographic evidence of condylar neck fracture

E. ,I. BARTON,

R.D.S.,”

KIRMIIWHAM,

ALA.

REATMENT planning in fractures of the mandibular condyle is dependent upon an ability to diagnose accurately the degree of damage in that a.rea. Surgical intervention such as open reduction or complete condyleetomy should be performed only after thorough clinical examination and study of adequate roentgcnographic films. These films should include views of both the injured and uninjured condyles in at least three planes. These will show the extent of the fracture and the resultant relationship of the fragments. A simultaneous view of both sides to allow evaluation of the relative positions of the condyles to t.he base of the skull and to each other is also deemed necessary. Such information is provided by the three projections to be described. These projections are made with a dental x-ray unit, the patient being seated in a dental chair. It is important that an aluminum filter of at least I mm. thickness be interposed between the tube and the subject because of the short target-skin In all cases described, screen distance utilized in the first two projections. and film of similar characteristics to those used are available from other manufacturers. 1. Lateral or Transcranial Condyle Projection.--(Fig. 1.) This is a modification of the original Parma Meth0d.l Technique: A 5 by ‘7 inch cardboard film holder containing Kodak NoScreen film is centered over the approximate position of the condyle on the side to be examined. Hand pressure is maintained by the patient to keep the film parallel with the midsagittal plane of the head. The central ray is directed, via a point approximate1 y 1 inch anterior to the external auditory meatus of the opposite side and immediately below the zygomatic arch in that area, to the No cone is used. The head of the condylar neck on the side being examined. machine is angulated 7 degrees upward, and the open face of the unit touched Exposure factors are 20 Ma.S. at 60 KVP. flat against the fa,ce of the patient. Where possible, the patient is asked to open the mouth, affording a clearer view of the condyle as it leaves the glenoid fossa. *Fellow in Dontistry, of Alabama.

Department of Oral Roentgenology, School of Dentistry, U~liversity 58

ROENTGENOGRAPHIC

EYIDEENCE

Oh’ CONDYLAR

NECK

FRACTURE

59

Couerage: This projection (Fig. 2 j shows (a) the vertieal or horizontal direction of the fracture line, (b) the anteroposterior relation of the fragments, and (e) dislocation of the head of the condylc in tither an anterior or posterior direction.

Fig.

7.

R.

c. mg.

3.

62

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J.

EshfirON

2. ~~t~ro~oster~o~ ~~a~sorb~tal Condyle P~~jee~~o~,---(~ig~ 3, il.) %‘echniyzce: A 5 by ? inch cardboard film holder containing Kodak ilo8wBerx film is steadied between the patierlt's head a& the headrest of the dental rhwir 011 Ihe side to be examined. and by the pai,iont’s hiind at l,he inferolatersl calmer of the holder. edge of t*he film is parallel with the ground The upper and at the level of the patient’s ear. The outer edge of the film extends laterally The film inclines anteriorly both about 3 inches beyond the side of the fact. laterally aad inferiorly to form angles of approximately 20 dcgrecs with the transverse and midsagittal pla.nes oi-’ the head. The central ra.g is directed posteriorly,

laterally,

a.nd

downward

throngh

Rig.

the

medial

a,spc,ct

of

ihe

orbit

at

6.

approximately 30 degrees toward a point judged to be 1 inch below the head of the condyle on the side to be examined (Fig. 3, I? and C). A pointed plastic cone is used and is placed gently at the inner canthus of the closed cyc of the patient. Exposure &ctors are approximately 20 Ma.9. and 60 KVP with 1.00 mm. a.luminum filtration. Coverage: This projection (Fig. 4) shows (a) the lateromedial relationship of the fragments (b) lateral or medial displacement of the head of the condyle, and (c) the degree of overlapping of the fragments vertically due to muscle influence.

3. Superoinferior Technique: An Kodak Blue Brand forward to rest his held by the pa.tient

Eregma-Gonion Projection of Both Condyles-(Fig.

5.)

8 by 10 inch easette with Buck Mid-Speed Screens and film is used. The patient is seated in the chair and leans elbows on his knees with neck extended. The ca,sctte is below the mandible, pamllcl with the floor, and e&ending

ROENTGENOt;RhI”HIC

EVIDENCE

OF

CONDYLAR

NECK

FRACTURE

6” ;)

as far into the clavicular region posteriorly as possible. The chin is extended as far forward as possible, attempting to parallel the lower border of the mandible with the cassette. Using a target-film distance of approximately 24 inches, the central ray is directed through the midsagittal plane of the head along a line joining the bregma and the angle of the mandible (gonion), a caudal angulation of approximately 50 degrees being needed. A dental unit opcrating at 70 KVP requires 50 to 60 Na.S. for adequate exposure, depending upon the size of the patient’s head and variations in calvarirtm density. Cowe?.age: This projection (Fig. 6) demonst,rates the positions of both condyles relative to the base of the skull and their angnlation to each other. Any rotational tendency of the condyles in the fossae becomes evident. The roentgenograms used arc those of a case presenting a greenstick type fracture of the neck of the eondyle. Since there is no displacement, this particular fracture is visible only in the anteroposterior transorbital projection.

Reference 1. Parma,

C.:

Die Rtintgendiagnostik

dos Kiefergelenkcs,

Bihtgenpraxiu

4: 633-649, 1932.