Introduction. patterns of injury. The injury pattern produced vanes with. j the object striking the face.

Transcription

1 Dolan et al. Facial fractures I Introduction Facial injury constitutes a frequent finding among emergency room patients. Schultz and Oldham estimate that 54% of such patients will have significant trauma. The complexity of facial structures and their relative vulnerability make it important for the radiologist to have an excellent understanding of facial osseous anatomy and patterns of injury. The injury pattern produced vanes with the force applied and the portion of the face that receives the blow. Variations may also occur as a result of the size of j the object striking the face. Facial injury evaluation plays a small role in the severely injured patient s overall evaluation. Survey table-top frontal and lateral views may suffice to detect the presence of an injury that can be more completely studied when the patient has reached a stable condition. We customarily use a 25 X 30 cm film in our maxillofacial evaluation and advise against the use of small coneddown views such as those used for sinus studies. Ideally, the Waters and Caldwell views should be obtained as posteroanterior views so that the facial bones, being close to the film, are optimally recorded. The posteroanterior projection also gives the best representation of the orbital, maxillary, and zygomatic structures because they diverge from back to front. Kenneth D. Dolan, M.D. Professor of Radiology Charles G. Jacoby, M.D. Associate Professor of Radiology Wendy R. K. Smoker, M.D. Assistant Professor of Radiology University Hospitals & Clinics, Iowa City, Iowa Complex motion (pluridirectional) tomography is preferred for facial injury evaluation since the blurring of overlying structures is most complete and parasite lines are minimized with this system. We use tomography to display details of injury that are obscure or, at most, are only suspected on plain radiographs. Tomography may also be of value in studying the extent of injury in patients who, because of multiple injuries, cannot cooperate for routine views. Computed tomography (CT) has also become signif i- cant in evaluating facial injury. Intraorbital and retrobulbar hematomas are difficult to detect by conventional means, but are easily displayed on CT. Similarly, bone detail and displacement may be clearly demonstrated by bone mode CT examination; i.e., CT examination with window and level settings adjusted to optimize bone images. Reconstruction of coronal and sagittal images by CT also may be very important, although sometimes the seriously injured patient may not be able to remain motionless long enough to allow the collection of transaxial data sufficient to permit reconstruction. The purpose of any radiographic study of the patient with facial injury is: 1, to provide the surgeon with information regarding the major interruptions of the facial skeleton and 2, to demonstrate any displacement of the fracture fragments that may be present. Surgical techniques of fracture reduction and stabilization are based on such information. Similarly, neural injury may be suggested by the location of a fracture or occasionally may be directly demonstrated by CT. Cerebrospinal fluid leaks may result from fractures of the frontal, ethmoidal or sphenoidal sinus walls. Early in the course of injury, hematoma or soft tissue herniation may occlude the site of injury. The radiologist may suggest the potential of such a leak, however, when the central sinus walls are interrupted. Volume 4, Number 4 July 1984 RadioCraphics 577

2 Facial fractures Dolan et al. II Normal Anatomy A. SKELETAL ANATOMY The facial skeleton arises from and is attached to the anterior cranial fossa and the sphenoidal bones. The broad frontal bones have indentations produced by the frontal lobe gyri as seen from above in Figure 1. The paired cribriform plates divide the central frontal surface. The crista galli is located between the cribriform plates. The falx cerebri arises from the crista galli and is attached along a vertical ridge lying behind the frontal sinuses. FIgure 1 View of the anterior fossa of a dried skull preparation seen from above 1. Cerebral surface of frontal bone 2. Falcine crest 3. Crista galli 4. Cribriform plate 5. Junction of frontal bone and lesser wing of the sphenoidal bone 6. Lesser wing of sphenoidal bone and anterior clinoid process 1. Orbits The orbital cavities are conical in shape and have central axes that diverge obliquely about 35#{176} from midline. The orbital axes project downward about 15#{176} from the posterior apices to the anterior rims. The orbital roof primarily consists of the yoke-like frontal bone. Near the orbital apex, the lesser sphenoidal wings complete the roof and form the upper margin of the superior orbital fissure. Perpendicular curved surfaces form the medial and lateral walls of the orbits. The ethmoidal sinus complex forms the principal medial surface of the orbit. This surface is known as the lamina papyracea. Posteriorly, this surface merges with the lateral wall of the sphenoid sinus. Anteriorly, the lamina papyraeea joins the lacrimal bone. This merges with the frontal process of the maxilla which is attached to the nasal bones. The posterior two-thirds of the lateral orbital wall is formed by the greater sphenoidal wing and its orbital process. The orbital process of the zygoma comprises the antenor one-third of the lateral orbital wall. Both sphenoidal and zygomatic contributions are attached to the orbital process of the frontal bone. The orbital floor, formed by the maxillary sinus roof, is sigmoid-shaped from back to front. The anterior floor is concave from the maxillary junction with the lamina the papyracea to the maxillary process of the zygoma. Posteriorly, the inferior orbital fissure separates the maxillary and greater sphenoidal wing surfaces of the orbit. The infraorbital neurovascular structures pass through a groove in the posterior one-half of the orbital floor. Anteriorly, the infraorbital neurovascular structures pass through an enclosed canal just below the orbital floor and exit through the infraorbital foramen. Since the orbital floor is only a thin layer of bone, it provides little skeletal support and depends on the thickened maxillary and zygomatic portions of the inferior orbital rim for support. 2. Zygomatic Arches The curved zygomatic arch forms a horizontal buttress extending from the body of the zygoma to the temporal process of the zygomatic arch. The temporal portion arises from a condensation of bone just above the glenoid fossa of the temporomandibular joint. 3. Maxillae The anterior, nasal and posterolateral maxillary sinus walls form a pyramidal space whose walls, seen in transverse section, form a triangle. An anterior buttress forms the nasal fossa margin. Laterally, thickening extends from the zygoma 578 RadioGraphics July 1984 Volume 4, Number 4

3 Dolan et al. Facial fractures I ; 1 9, to the alveolar arch. Posterior strengthening is produced by the fused pterygoid process of the sphenoid. The convex dental alveolar portions of the maxila are attached to the convex hard palate which forms a horizontal supporting structure. The perpendicular bony nasal septum is formed by the ethmoidal plate and the vomer. This provides tenuous vertical support for the nasal bones and hard palate. B. RADIOGRAPHIC ANATOMY, I Figure 2A A dried skull preparation in the Caldwell position for comparison with Figure 2B. 1. The Caidwell (Occipitofrontal) View The Caldwell projection should be made with the central ray directed about 250 below the canthomeatal plane to allow visualization of the orbital floor above the petrous ridge (Figure 2B). Figure 2B Radiograph of the skull In the Caldwell projection Anatomic features are identified in the accompanying key in the sequence suggested for the study of this view. 1. Zygomaticofrontal suture 2. Orbital process of frontal bone 3. Anterior orbital roof 4. Upper (palpable) rim of orbit 5. Frontal sinus 6. Lamina papyracea 7. Posterior orbital floor 8. Posterior lacrimal crest 9. Anterior orbital wall 10. Frontal process of maxilla 1 1. Lateral nasal wall 12. Lateral maxillary wall 13. Hard palate 14. Perpendicular ethmoid plate and vomer 15. Superior orbital fissure 16. Oblique orbital line 17. Orbital process of zygoma Volume 4, Number 4 July 1984 RadioGraphics 579

4 Facial fractures Dolan et al. B. RADIOGRAPHIC ANATOMY Figure 2C An anterior, pluridirectional, coronal tomogram showing the crista gail(c) and the ethmoldalsinus roof (fovea ethmoidalls) (E) The cribriform plate lies between these structures. Inflammatory mucous membrane thickening partly opacifies the right maxillary sinus. C=crista galli E=ethmoidal sinus roof-fovea ethmoidalis 3. Anterior orbital roof 8. Posterior lacrimal crest 9. Anterior orbital floor 1 1. ateral nasal wall 13. Hard palate 14. Perpendicular ethmoid plate and vomer Figure 2D A dried skull preparation cut through the same plane as that shown in Figure 2C, for comparison 580 RadioGraphics July 1984 Volume 4, Number 4

5 Dolan et al. Facial fractures Figure 2E A coronal tomogram 2 cm posterior to the plane of Figure 2C, to illustrate the continuity of the lamina papyracea and the posterior orbital floor 6. Lamina papyracea 7. Posterior orbital floor 1 1. Lateral nasal wall 13. Hard palate 14. Perpendicular ethmoid plate and vomer 16. Oblique orbital line Figure 2F A dried skull preparation cut through the same plane as is shown in Figure 2E Volume 4, Number 4 July 1984 RadioGraphics 581

6 Facialfractures Dolan et al. B. RADIOGRAPHIC ANATOMY 2. The Waters (Occipitomental) View The Waters projection (Figure SA) uses an occipitomental central ray with the patient s nose and chin against the film holder. The maxillary sinuses are projected above the petrous ridges. The entire zygomatic arch is visible if the view is obtained as a posteroanterior projection. We do not recommend tomography in this position since the main horizontal facial features-the maxillary alveolus and the orbital floor and roof-are no longer perpendicular to the tomographic plane and may not be sharply visible as they are in the Caldwell position. Figure 3A A radiograph of the skull in the Waters projection Anatomic features visible in this view are given in the accompanying key in the sequence suggested for the study of this view. 1. Zygomaticofrontal suture 2. Orbital process of frontal bone 4. Upper (palpable) rim of orbit 5. Frontal sinus 6. Lamina papyracea 7. Posterior floor of orbit 18. Glenoid fossa of temporomandibular joint 19. Upper margin of zygomatic arch 20. Lower margin of zygomatic arch 12. Lateral maxillary wall 13. Hard palate 21. Lower (palpable) rim of orbit 22. lnfraorbital foramen 23. Nasal arch 582 RadioGraphics July 1984 Volume 4, Number 4

7 Dolan et al. Facial fractures B. RADIOGRAPHIC ANATOMY Figure 3B A dried skull preparation in the Waters position, for comparison with Figure 3A Volume 4, Number 4 July 1984 RadioGraphics 583

8 Facial fractures Dolan et al. B. RADIOGRAPHIC ANATOMY 3. The Lateral View In the lateral view (Figure 4), structures on the two sides tend to overlap and to obscure one another. The sella turcica is well visualized and serves as a guide to the planum sphenoidale (roof of the sphenoid sinuses). The planum and the nasal surface of the hard palate should parallel each other. An imaginary perpendicular line connecting the anterior surface of the frontal sinus, the anterior nasal spine and the mandibular symphysis should parallel a perpendicular line along the greater sphenoidal wing and posterior maxilla. These relationships help to define the normal positions of the bones on the lateral view. The lateral position, like the Caldwell view, is a major projection for the tomographic evaluation of facial injury (Figures 5A-F). Figure 4 A radiograph of the skull in the lateralprojection Note the relationships cited in the text. 1. Sella turcica 2. Planum sphenoidale 3. Nasal surface of hard palate 4. Frontal sinus anterior surface 5. Anterior nasal spine 6. Symphysis of mandible 7. Greater sphenoidal wing 8. Posterior maxillary sinus wall 584 RadioGraphics July 1984 Volume 4, Number 4

9 Dolan et al. Facial fractures B. RADIOGRAPHIC ANATOMY Figure 5A A lateral view of a dried skull preparation for comparison with Figure 5B. Figure 5B A lateral tomogram through the zygomatic recess of the maxillary sinus and zygomatic and frontal processes of the lateral orbital wall 1. Frontal process of orbit 2. Zygomaticofrontal suture 3. Zygomatic process of orbit 4. Anterior surface of zygomatic recess of maxilla 5. Posterior wall of zygomatic recess 6. Coronoid process of maxilla 7. Mandibular condyle 8. Greater sphenoidal wing Volume 4, Number 4 July 1984 RadioGraphics 585

10 Facial fractures Dolan et al. B. RADIOGRAPHIC ANATOMY Figure 5C A dried skullpreparat!on cut through the outer one-third of the orbit to show the lateral orbital wall The orbital roof and sphenoidal wing are seen in section as is the zygomatic recess of the maxillary sinus. The zygomaticofrontal and zygomaticosphenoidal sutures can be followed from the lateral orbital border to the inferior orbital fissure. 1. Zygomaticofrontal suture 2. Zygomaticosphenoidal suture 3. inferior orbital fissure 4. Zygomatic recess of maxillary sinus 5. Orbital roof 6. Greater sphenoidal wing Figure 5F A midline sagitta! tomogram The position is best defined by the sella turcica. The frontal sinus surfaces are well visualized. The palatal horizontal buttress and the perpendicular vomer are also well shown in this view. 1. Anterior frontal sinus wall 2. Posterior frontal sinus wall 3. Sella turcica 4. Hard palate 5. Vomer 586 RadioGraphics July 1984 Volume 4, Number 4

11 Dolan et al. Facial fractures B. RADIOGRAPHIC ANATOMY Figure 5D A sagittal tomogram through the midorbit The fused maxillary posterior wall and pterygoid process are well seen. Figure 5E A comparative dried skull preparation cut through the same plane as that shown in Figure 5D 1. Orbital roof 2. Lesser sphenoidal wing-anterior clinoid process 3. Anterior maxillary sinus wall 4. Alveolus 5. Orbital floor (maxillary sinus roof) 6. Posterior maxillary sinus wall 7. Pterygoid process 8. Pterygomaxillary fossa 9. Superior orbital fissure Volume 4, Number 4 July 1984 RadioGraphics 587

12 Facial fractures Dolan et al. B. RADIOGRAPHIC ANATOMY 4. The Basal View The submentovertex position (Figure 6A) is of value in assessing the zygomatic arches and mandible, but may not be obtainable in the case of severe facial injury. Information about the frontal sinus walls, the lateral orbit, the lateral maxillary sinus wall and the greater sphenoid wing may also be obtained. In the edentulous patient, one may also see the lateral margins of the nasal fossa. Figure 6A A radiograph of the skull in the submentovertex projection, illustrating the anatomic features to be identified in this basal view 1. Zygomatic arch 2. Lateral maxillary sinus wall 3. Lateral orbital wall 4. Greater wing of the sphenoid 5. Mandibular condyle 6. Horizontal mandibular ramus 7. Anterior frontal sinus wall 8. Posterior frontal sinus wall 9. Lateral nasal fossa 588 RadioGraphics July 1984 Volume 4, Number 4

13 Dolan et al. Facial fractures B. RADIOGRAPHIC ANATOMY Figure 6B A dried skull preparation, viewed from below, in the basal position to show the continuity of the zygomatic arch between the temporal and maxillary extremities. Compare with Figure 6A. G=Glenoid Z=Zygomatic M=Maxilla fossa arch Volume 4, Number 4 July 1984 RadioGraphics 589

14 Facial fractures Dolan et al. C. COMPUTED TOMOGRAPHIC (TRANSAXIAL) ANATOMY The basal tomographic examination shows the same structures as the transaxial CT views. We customarily obtain layers 0.5 cm thick and in contiguous planes beginning at the maxillary alveolus level and continuing through the frontal sinus area. These views best illustrate the perpendicular buttresses of facial structures. The transaxial planes recorded by CT should show horizontal structures also, but frequently they are slightly oblique so that the hard palate, zygomatic arch and orbital floor and roof may be seen only in part on a given section. Anatomic structures present in the four principal transaxial CT planes are illustrated in Figure 7. Figure 7A Transaxial CT scan located in the plane of the dentalalveolus A maxillary retention cyst produces opacity on the reader s left. 1. Anterior nasal spine 2. Anterior hard palate 3. Maxillary tuberosity 4. Vertical ramus of mandible 5. Medial pterygoid muscle 6. Masseter muscle 590 RadioGraphics July 1984 Volume 4, Number 4

15 Dolan et al. Facial fractures C. COMPUTED TOMOGRAPHIC (TRANSAXIAL) ANATOMY Figure 7B Transaxial CT scan through the midmaxillary plane Maxillary sinus detail is most evident in this plane which is 16 mm above the plane of Figure 7A. 1. Lateral maxillary wall 2. Anterior zygomatic arch 3. Anterior maxillary surface 4. Section of infraorbital canal 5. Bony canal for lacrimal duct 6. Nasal pyramidal process of maxilla 7. Perpendicular ethmoidal plate 8. Vomer 9. Medial maxillary sinus wall 10. Pterygoid process 1 1. Mandibular condyle 12. Tympanic surface of temporomandibular joint Volume 4, Number 4 July 1984 RadioGraphics 591

16 Facial fractures Dolan et al. C. COMPUTED TOMOGRAPHIC (TRANSAXIAL) ANATOMY Figure 7C Transaxial CTscan in the plane of the orbital floorthis plane represents the major horizontal position of the midface. The entire zygomatic arch may be seen. The posterior maxillary sinus air cell extends upward as seen in the lateral view of the midorbit. The nasal bone and the frontal process of the maxilla are now evident anteriorly. The anterior and posterior lacrimal crests #{176}nclosethe lacrimal fossa along the medial orbital border. 1. Zygomatic arch 2. Nasal bone 3. Frontal process of maxilla 4. Anterior lacrimal crest 5. Posterior lacrimal crest 6. Mandibular condyle 7. Tympanic bone 8. Upper maxillary sinus 9. Sphenoidal sinus cell in base of pterygoid process 592 RadioGraphics July 1984 Volume 4, Number 4

17 Dolan et al. Facial fractures C. COMPUTED TOMOGRAPHIC (TRANSAXIAL) ANATOMY Figure 7D Transaxial CT scan in the plane that passes through the center of the orbit, the ethmoidal and the sphenoidal sinuses The zygomatic and sphenoid orbital processes form the lateral wall which connects posteriorly to the greater sphenoidal wing. 1. Glabella 2. Lamina papyracea 3. Ethmoidal sinus cell complex 4. Zygomatic portion of lateral orbit 5. Sphenoidal process of lateral orbital wall 6. Greater wing of sphenoidal bone 7. Sphenoidal sinus 8. Superior orbital fissure Volume 4, Number 4 July 1984 RadioGraphics 593

18 Facial fractures Dolan et al. D. THE OBLIQUE ORBITAL LINE The oblique orbital line is produced by the orbital process of the sphenoid, which contributes to the lateral orbital wall. This process is well visualized on the midorbital, transaxial CT plane (Figure 7D). The oblique orbital line is also present in the Caldwell (Figure 2B) and Waters (Figure SA) views. Figure 8 is an anterior view of a facial skeleton preparation in which drill cuts have been used to define different parts of the lateral orbital wall. Figure 8 Anterior view ofa dried facialskeleton preparation (1) Drill cut through the orbital process of the zygoma posterior to the zygomaticofrontal suture. This cut lies lateral to the oblique orbital line. (2) Cut through the orbital process of the sphenoid which interrupts the oblique orbital line. If this cut is continued further posteriorly into the greater wing proper, the lucent line extends through the oblique orbital line and both medially and laterally into the greater wing proper as in cut (3). 594 RadioGraphics July 1984 Volume 4, Number 4

19 Dolan et al. Facial fractures D. THE OBLIQUE ORBITAL LINE Surgical confirmation of the anatomical significance of the oblique orbital line is found in Figures 9A and 9B. The Naquin-Reece lateral orbitotomy is a procedure by means of which the surgeon gains access to retrobulbar structures through a resection of the thin sphenoidal and zygomatic processes of the lateral orbital wall. Following this resection, the oblique orbital line disappears as seen in Figure 9A. Figure 9A Ca/dwell view of the skull after a right Naquin-Reece orbitotomy The oblique orbital line is absent. Volume 4, Number 4 July 1984 RadioGraphics 595

20 Facial fractures Dolan et al. D. THE OBLIQUE ORBITAL LINE The Kronlein procedure is another orbitotomy procedure in which the entire lateral orbital wall is removed as far back as the greater wing of the sphenoid. This type of resection also removes the oblique orbital line as demonstrated by Figure 9B. Since we already know the orbital process of the zygoma does not produce the oblique orbital line (Figure 8), the orbital process of the sphenoid must produce this line. Figure 9B High Ca/dwell view of the skull after a left Kronlein orbitotomy The oblique orbital line is absent. Some authors have attributed the oblique orbital line to a portion of the greater sphenoid wing peripheral to the orbital process. Again, surgical evidence refutes this idea. The Caidwell view in Figure 9C demonstrates a large craniotomy, involving the right frontal bone and greater sphenoid wing, which was made to permit the surgeon to place a clip on a carotid aneurysm. The sphenoidal portion of this flap extended to the edge of the orbital process as seen in the basal view illustrated in Figure 9D. Yet the oblique orbital line is clearly defined on the Caidwell view. 596 RadioGraphics July 1984 Volume 4, Number 4

21 Dolan et al. Facial fractures Figure 9C Ca/dwell view of the skull after a right frontal sphenoidal bone resection to permit clipping ofa carotid artery aneurysm The oblique orbital line is present. Figure 9D Basal view of the skull This shows resection of the lateral part of the greater wing of the sphenoid on the right. Volume 4, Number 4 July 1984 RadioGraphics 597

22 Facial fractures Dolan et al. D. THE OBLIQUE ORBITAL LINE The radiographs illustrated in Figures 1OA-D show the value of assessing the oblique orbital line as an index to the presence of more extensive injury involving the posterolateral portion of the orbit. Figure 1OA Ca/dwell view of the skull This patient has a slightly displaced left tripod fracture (not clearly shown in this projection) and interruption of the caudal oblique orbital line. This allows one to see the transverse fracture extending into the superior orbital fissure (vertical arrows). 598 RadioGraphics July 1984 Volume 4, Number 4

23 Dolan et al. Facial fractures D. THE OBLIQUE ORBITAL LINE Figure lob Waters view of the skull This patient has an extensive fracture of the frontal sinus wall and upper orbital rim on the right (both poorly seen in this projection). The oblique orbital line is interrupted (arrow) suggesting extension of the frontal fracture across the orbital roof. This was confirmed by tomography. Volume 4, Number 4 July 1984 RadioGraphics 599

24 Facial fractures Dolan et al. D. THE OBLIQUE ORBITAL LINE Figure loc Waters view of the skullthis patient who has a right tripod fracture has an interrupted oblique orbital line (horizontal arrows). Lateral to the oblique orbital line separation, one can follow the fracture (vertical arrow) which extends posterolaterally into the temporal fossa. Figure lod Caldwell view of the skull showing avulsion of the zygoma and orbital process of the sphenoid The oblique orbital line is absent. The greater wing of the sphenoid and superior orbital fissure are intact. 600 RadioGraphics July 1984 Volume 4, Number 4

25 Dolan et al. Facial fractures III Radiological Signs of Facial Injury A. SUGGESTIVE SIGNS 1. Soft Tissue Swelling Figure 11 Soft tissue swelling may decrease the radiolucency of a facial area after injury. On facial radiographs, one may detect the hematoma produced at a contact point; the soft tissue opacity should signal the possibility of an underlying fracture. Hematomas are most easily detected in the nasofrontal, periorbital or malar areas on plain radiographs (Figure 15B, page 606). CT examination has added a new aspect to facial injury by clearly depicting the soft tissues. Figure 11 illustrates the presence of periorbital and preseptal soft tissue swelling after injury. No fracture was found. The patient whose CT scan is depicted in Figure 12A had right proptosis and decreased vision following injury. In this transaxial section the retrobulbar muscle cone is clear. Figure 11 The value ofctin the demonstration of orbital hematoma This transaxial CT section represents the plane of the midorbit in a patient with an extensive preseptal, periorbital hematoma on the left. Figure l2a Figure l2a The value ofctin the demonstration oforbitaihematoma This is a similar midorbit CT section in a patient with proptosis on the right. Volume 4, Number 4 July 1984 RadioGraphics 601

26 Facial fractures Dolan et al. A. SUGGESTIVE SIGNS Another section, 6 mm higher, shows a large hematoma (Figure 12B). An oblique lateral reconstruction in the plane of the globe and optic nerve shows the hematoma interposed between the orbital roof, upper muscle cone and optic canal. No fracture was found. 2. Fluid in a Paranasal Sinus Changes in the radiolucency of a sinus should signal possible injury. An air-fluid level or complete opacification may, however, be the residuum of antecedent sinus disease or may simply indicate displacement of blood into a sinus secondary to a severe nosebleed. Figures l2b & C The value ofctin the demonstration of orbital hematoma (B) A more superior CT section in the same patient as (A) shows a large hematoma filling the posterior right orbit. (C) An oblique longitudinal reconstruction shows the hematoma under the orbital roof compressing the globe, the muscle cone and the optic nerve. G = globe; H = hematoma; 1 = orbital roof; 2 = inferior margin of optic nerve. 602 RadioCraphics July 1984 Volume 4, Number 4

27 Dolan et al. Facial fractures B. DIRECT SIGNS When present, the following radiographic signs are consistent with facial fracture. The principal difference in the radiographic appearance of each of these signs has to do with the way in which the minor fracture fragment is displaced in relation to surrounding bone. 1. Separation Sign (cortical defect) Figure 1OA Detail If a fracture fragment is displaced away from surrounding bone, a small space is produced which on radiographs produces an interruption in bone continuity. We have demonstrated separation of the oblique orbital line for example in Figures ba-c. Separation may also occur along a suture (Figure 16, page 607). Figure lob Detail Figure 1OC Detail Volume 4, Number 4 July 1984 RadioGraphics 603

28 Facial fractures Dolan et al. B. DIRECT SIGNS 2. Overlap Sign If a compressive force produces a fracture, the fragment may be displaced so that it overlaps adjacent bone and produces a double density along the overlapping parts. Displacement of the anterior fragment of a zygomatic arch fracture in Figure 13 produces the overlap sign. Figure 13 Overlap sign This Waters view of a right zygomatic arch fracture illustrates the overlap sign (arrow). 604 RadioCraphics July 1984 Volume 4, Number 4

29 Dolan et al. Facial fractures B. DIRECT SIGNS 3. Abnormal Linear Opacity When a fracture fragment is rotated so that its long axis becomes aligned with the x-ray beam, a nonanatomical linear opacity is produced. This sign has been termed the abnormal linear density by Merrell. Displacement of a lateral maxillary wall fragment produces the abnormal linear opacity in Figure 14. Duplication of the oblique orbital line is sometimes seen and is due to the same sort of displacement of the lateral orbital wall. Figure 14 Abnormalllnearopacityln this Waters view of a left tripod fracture, an abnormal linear opacity is seen (arrow). The abnormal linear opacity is produced by a displaced maxillary wall fragment. There is also duplication of the left oblique orbital line as a result of displacement of a portion of the orbital process of the sphenoid. Volume 4, Number 4 July 1984 RadioCraphics 605

30 Facial fractures Dolan et al. B. DIRECT SIGNS 4. Disappearing Fragment This sign is the opposite of the abnormal linear opacity sign. A structure that ordinarily produces a cortical absorption line in a normal patient may be rotated so that seems to disappear after injury. In Figure 15A, a 2 cm palpable inferior orbital border fragment has been rotated out of alignment with the beam and seemingly has disappeared. (As the reader may have assumed, the infraorbital nerve was injured and local numbness resulted after this injury.) After elevation, return to normal position and fixation by metal sutures to adjacent stable bone, the rim, as seen in Figure 15B, appears normal. Figures l5a&b Disappearing fragment sign (A) This Waters view of a patient who has sustained a local fracture of the infenor orbital rim (arrows) illustrates the disappearing fragment sign. (B) This figure shows restoration and wire suture fixation of the detached fragment seen in (A). The arrows point to postoperative periorbital hematoma. 606 RadioGraphics July 1984 Volume 4, Number 4

31 Dolan et al. Facial fractures B. DIRECT SIGNS 5. Periorbital or Subcutaneous Air I1 I... Penorbital air is most commonly the result of a lamina papyracea (ethmoidal) fracture. The nasofrontoethmoidal complex injury in Figure 16 produced bilateral periorbital air. We have also seen extensive facial subcutaneous air in patients with tnpod fractures. In such patients, air escapes from the maxillary sinus when the patient blows his nose. Intracranial air may also result from a fracture through the posterior frontal sinus wall or the ethmoidal or sphenoidal sinus roof. 6. Displaced Structure L -.. Figure 16 Periorbital air In this Caldwell view bilateral periorbital air (A) and nasofrontal suture separation (5) are seen. Injury may distort the position of a large fragment without revealing other definitive signs of a fracture on plain films. The patient whose radiograph is depicted by Figure 17 has extensive displacement of the left nasal arch, frontal process of the maxilla and much of the inferior orbital rim. Structural displacement, in comparison with the opposite side, is the main clue to this injury. In other forms of injury, there may be separation along one fracture margin and not along others. This occurs frequently in the case of tripod fractures (See Section V). Fragment displacement is a frequent finding on examination of fractures by CT. Figure 17 Displacement of a structure Comparison with the normal right side shows the left nasal bone, the frontal process of the maxilla and the inferior orbital rim fragment to be displaced. Volume 4, Number 4 July 1984 RadioGraphics 607

32 Facial fractures Dolan et al. IV Local Facial Fracture A portion of the orbit is involved in every form of fracture except the zygomatic arch fracture, the local nasal fracture and the LeFort I injury. Thus, evaluation of the orbital borders, orbital apex or optic canal is a requisite part of the identification of most facial fractures. Local fractures will be considered in the following order: Orbital floor (blowout) fracture Lower orbital rim fracture Nasal arch fracture Zygomatic arch fracture Upper orbital rim and frontal sinus fracture A. ORBITAL FLOOR (BLOWOUT) FRACTURE By definition, the orbital blowout fracture excludes an interruption of the orbital rim. A compressive force transmitted by the ocular and peniorbital soft tissues to the very thin floor of the orbit is the typical mechanism of blowout fracture. In our experience, a blow by a fist is the most common cause of injury. Emery et a!. report that more than half of the blowout fractures in their series were produced this way. We have also seen this injury as a result of a blow by an elbow, a tennis ball or a handball, and it may be seen in patients who have been injured in automobile accidents. Diplopia and enophthalmos are considered the most cornmon complications of a blowout fracture. Ocular injuries requiring treatment also occur and were present in 24% of the Emery series. Diplopia usually clears spontaneously. Enophthalrnos may be present at the time of injury if the depressed fracture fragment is large or may develop later as the penorbital hernatorna is absorbed. Hammerschlag s group was able to identify a blowout fracture, using the Waters and Caidwell views, in 97% of their cases. We agree that the majority of these fractures can be found on plain films. The suggestive signs listed above (soft tissue swelling and sinus opacification or air-fluid level) are often present with a blowout fracture. Definite displacement of bone spicules or a larger fragment should be the principal diagnostic criterion. The ethmoidal surface is involved in this fracture pattern in about 40% of cases. Thin-section tomography plays an important part in blowout fracture evaluation. If surgery is considered, tomograrns provide the best cross sectional study of the orbital floor and lamina papyracea. CT may provide evidence of orbital floor disruption in transaxial or coronal sections, but is a costly diagnostic medium. We reserve CT for the study of complicated cases that cannot be resolved by more conventional study. An undisplaced blowout fracture is illustrated by Figure 18A. Only a small soft tissue mass below the orbital floor is visualized on the Caldwell view in Figure 18B. Figures 18A & B Undisplaced right blowout fracture (A) This Waters view clearly demonstrates the fracture line (arrow). (B) A Caldwell view shows only an oval mass in the right maxillary sinus (arrow). 608 RadioGraphics July 1984 Volume 4, Number 4

33 Dolan et al. Facial fractures A. ORBITAL FLOOR (BLOWOUT) FRACTURE Volume 4, Number 4 July 1984 RadioCraphics 609

34 Facial fractures Dolan et al. A. ORBITAL FLOOR (BLOWOUT) FRACTURE Most often, the displaced blowout fracture fragment will appear as an abnormal opacity resembling a trapdoor that is hinged toward the ethmoidal side of the orbit. This type of injury is demonstrated by Figure 19. Peniorbital fat produces the soft tissue shadow protruding through the floor. In this case (Figure 19), upward gaze was limited and the forced-duction test was positive. If the blowout fragment reaches the posterior orbital floor, the cortical line will seem to disappear ( disappearing fragment sign) on the Caldwell view, as seen in Figure 20A. Usually the displaced floor will produce an abnormal linear opacity in the Waters view as demonstrated in Figure 20B. Figure 19 Mid floor blowout fracture on the leftthe arrow points to the fragment that simulates a trapdoor. 610 RadioGraphics July 1984 Volume 4, Number 4

35 Dolan et al. Facialfractures Figures 20A & B Posterior blowout fracture on the left (A) The posterior floor cortex is absent on the left at the arrow in this CaIdwell view. (B) In the Waters view, an abnormal linear opacity (arrow) represents the displaced orbital floor fragment. Volume 4, Number 4 July 1984 RadioGraphics 611

36 Facial fractures Dolan et al. A. ORBITAL FLOOR (BLOWOUT) FRACTURE CT was helpful in delineating the very large defect produced by a left blowout fracture in the patient whose studies are shown in Figure 21. The Caldwell view, Figure 21A, demonstrates a large lamina papyracea and orbital floor defect. Deep enophthalmos is suggested by the broad, air filled upper tarsal skin fold indicated by the arrows. Enophthalmos is confirmed by the midorbital, transaxial CT section shown in Figure 21B. This also shows a long ethmoidal surface indentation. The orbital floor and lower ethmoidal defects are confirmed in a lower transaxial CT scan (Figure 21C). The defects, especially the one in the orbital floor, are best seen in Figure 2bD, a direct coronal CT scan. Figures 21A & B Large left orbital floor and lamina papyracea defect (A) A Caldwell view shows absence of the cortices of the lamina papyracea and orbital floor. The left maxillary sinus is opacified and there is prominence of the tarsal fold (arrows). (B) In this midorbital transaxial CT scan, enophthalmos is present together with an ethmoidal surface defect. 612 RadioGraphics July 1984 Volume 4, Number 4

37 Dolan et al. Facialfractures., I Figures2lC&D Large left orbital floor and lamina papyracea defect(c) The ethmoidal and orbital floor defects are seen in this low orbital, transaxial CT scan. (D) A direct coronal CT scan shows the large defect. Volume 4, Number 4 July 1984 RadioGraphics 613

38 Facial fractures Dolan et al. A. ORBITAL FLOOR (BLOWOUT) FRACTURE The use of tomography in evaluating a blowout fracture of the orbital floor and lamina papyracea is illustrated in Figure 22. The increase in the volume of the orbit produced by this fracture (Figure 22) easily explains the persistent enophthalmos that was noted clinically in this patient. Figure 22 Blowout fracture Marked medial displacement of the lamina papyracea and downward displacement of the right orbital floor are seen in this tomogram of a blowout fracture. B. LOWER ORBITAL RIM FRACTURE Figures 15A & B Inferior orbital rim fracture (A) This detail shows disappearance of an inferior orbital rim fragment because of its rotation. (B) This detail shows reappearance of the fragment as a result of its surgical restoration to normal position. 614 RadioGraphics July 1984 Volume 4, Number 4

39 Dolan et al. Facial fractures B. LOWER ORBITAL RIM FRACTURE A blow directed to the lower orbital rim may produce a rim fragment such as that illustrated in Figures 15A and 15B. In this case, the direction of force caused rotation of the detached fragment so that it seemed to disappear. A more lateral segment of the inferior rim has been separated in the injury illustrated by Figure 23A. The detached fragment has been displaced downward and medially. In many inferior orbital rim fractures, a portion of the anterior orbital floor will be included in the fragment. Often the floor will be obscured by the rim fragment. In Figure 23B, the left rim fracture (upper arrows) and displaced orbital floor (lower arrows) are both evident. Less apparent is the lamina papyracea fracture indicated by thickening along this surface of the orbit. Figures 23A & B Inferior orbital rim fracture (A) There is downward and medial displacement of an outer orbital rim fragment (arrows). (B) An orbital rim fracture is seen at the upper arrows. A fragment of the orbital floor (displaced inferiorly) is seen at the lower arrows. Volume 4, Number 4 July 1984 RadioGraphics 615

40 Facial fractures Dolan et al. C. NASAL ARCH FRACTURE Nasal tip fractures are commonplace. Isolated fractures are best visualized on an underexposed lateral view. This view also can be used to define more severe injury to the bony margins of the nasal fossa. Interruption of the anterior nasal spine and premaxilla may also be defined by the lateral view. The patient whose radiograph is illustrated in Figure 24A, has extensive injury of the maxillary margins of the nose, anterior nasal spine, and premaxilla. Fragment separation in all of these fractures occurs in the sagittal plane and is, therefore, best seen in the lateral view. While fracture of the nasal arch might be suspected from the changes in Figure 24A, no direct evidence of such an injury is present on the lateral view. Since the nasal arch is oriented in a coronal plane, it is best seen in the Waters view. Figure 24B is from the same examination as Figure 24A. In this Waters view, both nasal bones are seen to have been separated from the perpendicular plate of the ethmoid and from both maxillary frontal processes. The left maxillary frontal process has been interrupted along the medial border of the maxillary sinus producing opacification of the sinus. A portion of the premaxilla injury can be seen between the central incisors. The facial surgeon is concerned about the airway and cosmetic appearance of the patient with a nasal injury. Therefore, information such as that recorded in Figures 24A and B can be very helpful to the surgeon. Figures 24A & B Extensive nasal injury (A) This lateral view shows a nasal tip fracture at the upper arrow, a fracture of the frontal process of the maxilla at the middle arrows and an anterior nasal spine fracture at the lower arrows. (B) This Waters view shows a nasal arch fracture at A, frontal process fracture at B, and a portion of the premaxilla fracture at C. 616 RadioGraphics July 1984 Volume 4, Number 4

41 Dolan et al. Facial fractures C. NASAL ARCH FRACTURE Nasal arch interruption may also signal more extensive injury of the orbital rim, orbital floor, ethmoidal sinus and frontal sinus. The left nasal bone and maxillary frontal process are separated from the remainder of the nasal arch in Figure 25A. The frontal process is separated also along the medial maxillary sinus border and at the medial edge of a displaced orbital rim fragment. The nasal bone and frontal process form a large fragment which has the shape of an inverted Y at the arrows. The entire orbital floor has been displaced downward. An accompanying Caidwell view, Figure 25B, shows the associated left lamina papyracea fracture and further demonstrates the extent of the orbital floor fracture. Figures 25A & B Left nasalarch fracture with frontal process, orbital rim and floor invoivement (A) This figure shows an inverted Y produced by fractures of the left nasal bone and the frontal process of the maxilla (upper 3 arrows). The orbital rim is detached and forms a disappearing fragment. There is an orbital floor fracture at the lower vertical arrow. (B) A lamina papyracea fracture is seen at the arrows. Volume 4, Number 4 July 1984 RadioGraphics 617

42 Facial fractures Dolan et al. C. NASAL ARCH FRACTURE A force applied to the left frontal, nasal and orbital areas produced the injury depicted by Figure 26. A stellate frontal sinus fracture extends along, and interrupts, the upper, inner border of the left orbital margin in Figure 26A. The nasal arch is comminuted and displaced downward. The perpendicular plate of the ethmoid and the vomer are separated in the center of the nasal septum. Rotation of the fragments representing the maxillary frontal process and the inferior orbital rim has resuited in a step-like deformity of the inferior rim, and the orbital floor is interrupted. In the Caldwell view, Figure 26B, the left maxillary frontal process displacement can be seen, and a blood clot opacifies the frontal sinus. Figure 26C is a lateral view that shows fractures of the upper and lower margins of the frontal sinus, as well as ethmoidal roof fractures. These changes should suggest that the patient may develop a cerebrospinal fluid leak. Figures illustrate the point that extensive central axis and orbital injury may accompany an interruption of the nasal arch. 618 RadioGraphics July 1984 Volume 4, Number 4

43 Dolan et al. Facial fractures C. NASAL ARCH FRACTURE Figures 26A, B & C Stellate frontal sinus fracture There is, in addition, depression of the nasal arch, fracture of the nasal septum, displacement of the frontal process of the maxilla and fracture of the orbital floor. (A) This Waters view shows a stellate frontal fracture and upper orbital rim fracture (open arrow). Rotation of the frontal process of the maxilla produces a step-off with the lower rim (curved arrow). A septum fracture is indicated by the horizontal arrows. (B) In this CaIdwell view comparison with the normal right side (arrows) confirms the displacement of the left frontal process of the maxilla. The frontal sinus is opacified. (C) The lateral view shows frontal fracture margins (arrows) and ethmoidal roof separation (arrowheads). Volume 4, Number 4 July 1984 RadioGraphics 619

44 Faclalfractures Dolan et al. D. ZYGOMATIC ARCH FRACTURE The zygomatic arch is vulnerable to a blow from the side of the face which produces fractures with inward (medial) displacement of the fragments centrally and outward (lateral) displacement of the fragments at the zygomatic and temporal ends of the arch. This fracture complex is easily detected in the Waters projection, as is seen in Figure 13. Occasionally, the anterior element of a zygomatic arch fracture may involve the body and the orbital process of the zygoma. The Waters view in Figure 27A demonstrates the central indentation of the zygomatic arch and the outward displacement of the temporal portion of the arch that is typical of an arch fracture. Anteriorly, the other fracture with outward displacement has occurred through the orbital process and body of the zygoma. The latter fracture is more evident in Figure 27B, the Caldwell view. Rarely, a zygomatic arch fracture will be accompanied by a transverse fracture through the body of the zygoma as seen in Figure 28. Figures 27A & B Zygomatic arch fracture with antenor component through the body and orbitalprocess ofthe zygoma(a) This Waters view shows inbending at A, temporal process outbending at B, perpendicular outbending through the zygoma at C. (B) A Caldwell view of the same patient shows extension of the fracture along the outer portion of the orbital process (arrows). 620 RadioGraphics July 1984 Volume 4, Number 4

45 Dolan et al. Facial fractures D. ZYGOMATIC ARCH FRACTURE Figure 13 Zygomatic arch fracture This detail shows the characteristic appearance of a zygomatic arch fracture as seen in the Waters view. Figure 28 Zygomatic arch fracture with transverse extension of the anterior fracture through the body of the zygoma Note the medial displacement ( inbending ) of the arch centrally at A, the lateral displacement of the temporal process ( outbending ) at B, and the transverse fracture of the zygoma at C. Volume 4, Number 4 July 1984 RadioGraphics 621

46 Facial fractures Dolan et al. E. UPPER ORBITAL RIM FRACTURE AND FRONTAL SINUS FRACTURE The upper orbital rim is infrequently fractured but may become vulnerable if the frontal sinus is large as in the case of the patient whose radiograph is illustrated in Figure 29. Figure 29 shows two large upper orbital rim fragments that have been displaced downward. Tomograms demonstrated involvement of only the anterior upper orbital rim and outer frontal sinus wall. Following reduction, the outer (lateral) fragment was wired to the stable orbital process of the frontal bone. The medial fragment was then anchored to the stabilized lateral fragment by another wire suture. Comminution prevented further suturing of the medial fragment, but as is seen in Figure 29A, the upper inner orbital rim was held in good position by soft tissues. Figures 29A & B Upper orbital rim fractures in a patient with a large frontal sinus (A) The fractures (arrows) produce two large fragments that are displaced downward. (B) Following reduction and fixation, the upper orbital border has been replaced in anatomic position. 622 RadioGraphics July 1984 Volume 4, Number 4

47 Dolan et al. Facial fractures E. UPPER ORBITAL RIM FRACTURE AND FRONTAL SINUS FRACTURE The application of more extensive force results in orbital roof, ethmoidal and orbital floor (blowout) fractures such as those seen in Figure 30. In this patient, the entire right upper orbital rim and adjacent frontal sinus wall are comminuted. The lamina papyracea is also fractured, and a long segment fracture of the orbital roof as well as a blowout fracture of the orbital floor are present. In such a case, one would expect detachment of the trochlear sling for the superior oblique muscle, and a cerebrospinal fluid leak might possibly develop. The patient s vision was intact. Figure 30 Comminuted fracture Involving the right upper orbital rim, the frontal sinus and ethmoid sinus A longitudinal orbital roof fracture (upper arrow) extends posteriorly through the lesser wing of the sphenoid. A blowout fracture is present at the lower arrow. Volume 4, Number 4 July 1984 RadioGraphics 623

48 Facial fractures Dolan et al E. UPPER ORBITAL RIM FRACTURE AND FRONTAL SINUS FRACTURE CT may be very helpful in the study of fractures involving the frontal sinus, but CT does not demonstrate the upper orbital rim well. A fracture of the anterior surface of the frontal sinus is well defined in Figure 3bA. Lower CT sections failed to show comminuted fragments along the upper, inner orbital rim, whereas, these were quite evident on plain radiographs. One might also be misled into thinking a large fracture fragment was present by the appearance of the normal superior orbital neurovascular grooves seen in Figure SiB. Figures 31A & B Comminuted, depressed fracture involving the anterior wall of the left frontal sinus and the inner, upper orbital rim (A) This CT section through the frontal sinus shows the depressed left anterior frontal sinus wall and opacification of the frontal sinus on the left. (B) This CT section, at a lower level, shows the fracture at the central arrow. The outer arrows indicate normal suborbital neurovascular grooves. 624 RadioGraphics July 1984 Volume 4, Number 4

49 Dolan et al. Facial fractures V The Tripod Fracture A. USUAL MANIFESTATIONS OF THE TRIPOD FRACTURE A number of regional terms have been applied to the form of fracture that involves the attachments of the zygoma. It has been referred to interchangeably as the zygomaticomaxillary fracture complex, the zygomaticofacial fracture, the trimalar fracture and the tripod fracture. The term tripod fracture is used throughout this discussion because it best reflects the three-legged stool arrangement of the zygoma and its principal attachments. Posteriorly, the narrow temporal process of the zygoma helps to form the zygomatic arch. Superiorly, the orbital process of the zygoma unites with the orbital process of the frontal bone at the zygomaticofrontal suture. The orbital process also has a thin posterior lamella that unites with the orbital process of the sphenoid to form the lateral orbital wall. Inferiorly, the broadest and most supportive part of the zygoma is found in the maxillary process which covers the superolateral margin of the maxillary sinus and which, in the well developed sinus, is pneumatized by the zygomatic recess of the sinus. The orbital portion of the zygomaticomaxillary suture reaches nearly as far as the infraorbital foramen. The tripod fracture results in separation of the zygoma from these three major bone attachments; hence, the tripod fracture implies an interruption of all three legs. An example of a left tripod fracture is illustrated in Figure 32. Force, which was directed in a medial and postenor direction, was applied over the body of the zygoma. An air-fluid level is present in the maxillary sinus, and an oblique fracture line spans the outer maxilla. The movable outer portion of the inferior orbital border is elevated. The mobile lateral portion of the maxilla is displaced medially. A line of separation is present in the zygomatic arch. All of these features are evident in the Waters view, Figure 32A. The Caidwell view, Figure 32B, best shows the zygomaticofrontal suture separation. The lateral orbital wall fracture is not evident in this projection, however. Figures 32A & B Left tripod fracture (A) This Waters view shows orbital rim interruption at A, a lateral maxillary fracture at B, and an undisplaced zygomatic arch fracture at C. (B) The Caldwell view shows a zygomaticofrontal suture separation at the arrow. Volume 4, Number 4 July 1984 RadioGraphics 625

50 Facial fractures Dolan et al. A. USUAL MANIFESTATIONS OF THE TRIPOD FRACTURE The right tripod fracture fragment in Figure SSA has been displaced downward so that the mobile, outer fragment of the inferior orbital rim lies below the level of the stable medial aspect of the rim. The lateral maxillary portion of the detached tripod fragment has been displaced medially producing a double line just above the alveolus. Downward displacement of the movable anterior portion of the zygomatic arch has also occurred. Zygomaticofrontal suture separation is more obvious on the Caldwell view in Figure SSB. After reduction, the restored orbital rim and zygomaticofrontal fixation points produced by wire sutures are illustrated in Figures SSC and D. Improvement in the position of the zygomatic arch and of the lateral maxillary wall fragment is also seen in these views. Figure 33A Figure 33B 626 RadioGraphics July 1984 Volume 4, Number 4

51 Dolan et al. Facial fractures A. USUAL MANIFESTATIONS OF THE TRIPOD FRACTURE Figure 33C Figure 33D Figures 33A-D Downward displacement ofa right tripod fracture(a) This Waters view shows the outer rim fragment at A to be in a lower than normal position. There is duplication of the lateral maxillary border at B, and downward displacement of the zygoma fragment at C. (B) The arrow marks separation of the zygomaticofrontal suture. Orbital rim and zygomaticofrontal fixation wires are seen in the postreduction Waters (C) and Caldwell (D) views. Volume 4, Number 4 July 1984 RadioGraphics 627

52 Facial fractures Dolan et al. B. SUPPLEMENTARY VIEWS FOR TRIPOD FRACTURES We have seen how valuable the Waters and Caldwell views are in evaluating the tripod fracture. The right tripod fracture illustrated by a Waters view in Figure 34A is barely visible because of its minimal displacement. A Towne projection of the same patient (Figure 34B) permits evaluation of the anterior, posterolateral and medial maxillary sinus walls. On the patient s left, the sinus margins are intact; on the right, extensive comminution of the anterior and posterolateral maxillary surfaces, as well as, posterior displacement of the zygoma are present. The zygomatic arch is usually too overexposed to view on a Towne projection, but may be seen in this projection on an underexposed radiograph. Figures 34A & B The Towne projection in tripod fracture evaluation (A) In the Waters view, a barely discernible right tripod fracture is seen. (B) The Towne projection shows the anterior, A, posterolateral, B, and medial, C, maxillary margins on the left to be intact. The anterior and posterolateral margins on the right are comminuted (arrows). 628 RadioGraphics July 1984 Volume 4, Number 4

53 Dolan et al. Facial fractures B. SUPPLEMENTARY VIEWS FOR TRIPOD FRACTURES The underexposed basal view is preferred for the evaluation of the zygomatic arch position and provides information about the position of the body of the zygoma, as well. A left tripod fracture is seen in the Waters view in Figure 35A. In this projection, a zygomatic arch interruption might be suspected from the angulation of the arch, but separation is not seen. Figure 35B, an underexposed basal view, clearly shows outward (lateral) bending of the zygomatic arch; it also demonstrates posterior displacement of the body of the zygoma. These findings are better seen in a detail of Figure 35B (Figure 35C). Pluridirectional tomography and CT are reserved for the evaluation of complications of the tripod fracture that will be considered in a subsequent section. 1 Figures 35A, B & C Left tripod fracture (A) A Waters view clearly shows the fracture. A line of separation between fragments (arrows) parallels the left oblique orbital line. (B) and detail (C) An underexposed basal view shows outbending of the zygomatic arch (horizontal arrow) and posterior displacement of the body of the zygoma (vertical arrow) when compared with the opposite side. Volume 4, Number 4 July 1984 RadioGraphics 629

54 .- Facial fractures Dolan et al. C. MANDIBULAR FUNCTION AND THE TRIPOD FRACTURE When the zygomatic arch portion of a tripod fracture extends into the glenoid fossa of the temporomandibular joint, pain on motion of the mandible may cause the patient to restrict motion. Such an injury simulates a mandibular condyle injury. The joint capsule may also be injured. Occasionally the tripod fragment will be so displaced that mandibular motion is physically restricted. The zygoma fragment in Figure 36A is displaced downward to such an extent that it rests against the coronoid process of the mandible. This prevented the patient from closing her mouth. The Caldwell view of this patient (Figure 36B) better shows the extent of the downward displacement of the tripod fragment. This patient also had fractures of the nasal arch, of the frontal process of the maxilla and of the left maxillary alveolus. The alveolar injury produced the oblique position of the upper teeth seen in these views. Figures 36A & B Tripod injuryand displacement preventing closure of mouth (A) The Waters view shows the zygoma, Z, to encroach on the coronoid process of the mandible, C. The nasal arch and the frontal process of the maxilla are also fractured. (B) This Caldwell view shows marked zygomatic displacement. :.. :tff4.. 1T-.%L?. l *1. _zo 630 RadioGraphics July 1984 Volume 4, Number 4

55 Dolan et al. Facial fractures C. MANDIBULAR FUNCTION AND THE TRIPOD FRACTURE Inability to close the mouth implies injury while the mouth was open; inability to open the mouth implies injury while the mouth was closed. The patient whose radiograph is seen in Figure 37, for example, was struck when his mouth was closed. The zygoma impinged on the coronoid process, and the patient could not open his mouth. The patient whose radiograph is illustrated by Figure 38 had a shearing fracture of the tip of the coronoid process secondary to the displacement of a tnpod fracture. Figure 37 Figure 37 Tripod injuryand displacement preventing opening of the mouth In this Waters view, the right zygoma, Z, is seen to be displaced against the coronoid process of the mandible, C. This prevents opening of the mouth. Figure 38 Right tripod fracture with fracture of the coronoid tip (arrow) Figure 38 Volume 4, Number 4 July 1984 RadioGraphics 631

56 Facial fractures Dolan et al. D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT IN TRIPOD FRACTURES A mandibular ramus fracture may be produced during the same sort of altercation that results in a tripod fracture. Such an injury is demonstrated in Figure 39. In the Waters view (Figure 39A), a left tnpod fracture is seen; the posteroantenor view (Figure 39B) shows the accompanying intercondylar mandibular fracture. Figures 39A & B Left tripod andassociated mandibular fractures (A) This Waters view shows a left tripod fracture (arrows). (B) A posteroanterior view shows an intercondylar fracture (arrow). 632 RadioGraphics July 1984 Volume 4, Number 4

57 Dolan et al. Facial fractures D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT IN TRIPOD FRACTURES Whereas the majority of tripod fractures involve the zygomaticofrontal suture, variations occur and require adjustments in surgical repair. For example, in Figure 40A, the zygomaticofrontal suture is intact, but the orbital process of the zygoma is interrupted. Orbital process fixation was achieved with a suture spanning the fracture (Figure 40B). Figures 40A & B Tripod fracture with low-lying orbital process fracture (A) This preoperative Waters view shows an irregular fracture line through the orbital process of the right zygoma rather than separation of the zygomaticofrontal suture. (B) This radiograph was made after surgical reduction and fixation of the fractures. Volume 4, Number 4 July 1984 RadioGraphics 633

58 Faclalfractures Dolan et al. D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT IN TRIPOD FRACTURES In another variation, the orbital process of the frontal bone may be sheared off in association with a tnpod fracture. When this occurs, there is usually an accompanying separation of the zygomaticofrontal suture, as well. This is seen in Figure 4iA in which there is medial displacement of both the zygomatic and frontal contnibutions to the lateral orbital wall. The surgeon, again, must adjust the suture fixation points to produce stability. This principle is illustrated in Figure 41B. Figures 4lA & B Tripod fracture with high orbital process fracture (A) This preoperative view shows a fracture through the base of the orbital process of the frontal bone (arrows). (B) The result obtained by reduction and fixation of the minor fragments is seen in this postoperative Waters view. 634 RadioGraphics July 1984 Volume 4, Number 4

59 Dolan et al. Facial fractures D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT IN TRIPOD FRACTURES Medial displacement of the orbital processes (or of the frontal bone) is usually accompanied by extensive orbital floor injury. This is seen in Figure 42 in which the transverse orbital dimension is markedly nanrowed by the displaced frontal process of the zygoma. The comminuted orbital floor is displaced into the maxillary sinus. Clinically, no ocular muscle entrapment was present, but lateral gaze was restricted. Figures 42A & B Medial displacement of the lateral orbital border with orbital floor interruption (A) A Waters view shows displacement of the orbital floor producing an abnormal linear opacity (arrow). (B) Comminution of the orbital floor (arrow) is shown in this Caldwell view. Volume 4, Number 4 July 1984 RadioGraphics 635

60 Facial fractures Dolan et al. D. VARIATIONS IN LATERAL ORBITAL INVOLVEMENT IN TRIPOD FRACTURES If the greater sphenoid wing portion of the lateral orbital bonder is injured, the oblique orbital line will be interrupted, and an overlap sign will appear where fragments are supenimposed as in Figure 43A. The spatial relationships of such fragments are best defined on transaxial CT as illustrated in Figure 43B. Figures 43A & B Right tripod fracture with Involvement of the orbital process of the greater wing of the sphenold(a) The CaIdwell view shows interruption of the oblique orbital line (vertical arrow) and an overlap sign (horizontal arrows). (B) This transorbital CT scan shows the overlapping (arrows) of the fragments in the transverse plane. 636 RadioGraphics July 1984 Volume 4, Number 4

61 Dolan et al. Facial fractures E. ORBITAL APEX AND OPTIC CANAL INJURY COMPLICATING THE TRIPOD FRACTURE, V.. r- If the force producing a tripod fracture is applied in the direction of the long axis of the lateral orbital wall, injury to the orbital apex and sunrounding structures may occur. Plunidinectional tomography and CT are useful for demonstrating suspected orbital apex injury. The patient whose radiograph is illustrated in Figure 44 had a right tripod fracture accompanied by diminished vision in the right eye. Careful evaluation of the Caldwell view revealed an abnormal linear opacity along the lateral bonder of the superior orbital fissure (Figure 44A). A section from a coronal tomognaphic study confirmed the presence of a fracture in the greater wing of the sphenoid and demonstrated a lessen sphenoidal wing fracture with clockwise rotatory displacement (Figure 44B). Opacity of the ethmoidal sinus was also present on the night. Figures 44A & B Right tripod fracture with orbital apexlnjury(a) A Caldwell view shows an abnormal linear opacity (arrow). (B) This coronal tomogram of the superior fissure area shows clockwise rotation of a lesser sphenoidal wing fragment with fractures (arrows). Volume 4, Number 4 July 1984 RadioGraphics 637

62 Facial fractures Dolan et al. E. ORBITAL APEX AND OPTIC CANAL INJURY COMPLICATING THE TRIPOD FRACTURE In Figure 45, the radiographs of another patient with a night tripod fracture and orbital apex injury are shown. Figure 45A is a coronal plunidirectional tomogram illustrating a lessen sphenoid wing fracture with clockwise rotation similar to that in Figure 44B. The lateral tomograms (Figures 45B and C) show the lessen wing and anterior clinoid process to have been separated from the planum sphenoidale and tubenculum sellae. Figures 45A, B & C Right tripod fracture with orbitalapex injury(a) This coronal polytomogram shows rotation of a lesser sphenoidal wing fragment with fractures (arrows). (B) A lateral polytomogram through the plane of the sella again shows separation of the lesser wing of the sphenoid (arrows). (C) A lateral parasellar polytomogram shows lesser wing and anterior clinoid separation (arrows). 638 RadioGraphics July 1984 Volume 4, Number 4

63 Dolan et al. Facial fractures E. ORBITAL APEX AND OPTIC CANAL INJURY COMPLICATING THE TRIPOD FRACTURE Volume 4, Number 4 July 1984 RadioGraphics 639

64 Facial fractures Dolan et al. E. ORBITAL APEX AND OPTIC CANAL INJURY COMPLICATING THE TRIPOD FRACTURE A CT study of a similar injury is illustrated by Figure 46. Figure 46A is a tnansmaxillany section showing interruption of the left anterior and postenolatenal maxillary sinus borders. Figure 46B is a transaxial section through the midorbit that shows angulated fragments of the orbital process of the greater sphenoidal wing displaced into the orbital apex. Ethmoidal and sphenoidal sinus opacity implies medial orbital wall injury. A coronal CT reconstruction shows how the border of the superior fissure formed by the greaten wing of the sphenoid has been displaced upward above the level of the lesser wing (Figure 46C). Thus, the tripod fracture may vary from a relatively minor flattening of the malan eminence, to a fracture that is associated with injury that can imperil vision. On occasion, a patient may have tripod fractures bilaterally. This is illustrated by Figure 47A. The examiner must make sure that the central nasofrontal axis is not injured in order to differentiate the bilateral tripod injury from the more extensive LeFort II injury. The Caidwell view (Figure 47B) shows zygomaticofrontal suture separation on the left; whereas, on the night, there is a transverse fracture of the orbital process below the suture. The result achieved by reduction and fixation of the fragments is shown in Figure 47C. Figures 46A, B & C Left tripod fracture with orbital apex injury(a) A transmaxillary CT scan demonstrates anterior and posterolateral maxillary fractures (arrows). (B) A transorbital CT scan shows displaced fragments (arrows) of the orbital process of the greater wing of the sphenoid encroaching on the apex of the orbit. The fragment at A would produce an abnormal linear opacity on plain films. (C) In this coronal reconstruction of CT data, eievation of the greater wing of the sphenoid is seen at the arrow. 640 RadioGraphics July 1984 Volume 4, Number 4

65 Dolan et al. Facial fractures Figures 47A, B & C Bilateral tripod fractures (A) This Waters view shows the transmaxillary (arrows) and arch fractures (arrowheads). (B) The zygomaticofrontal suture is separated on the left, but a fracture of the transverse orbital process (arrows) is present on the right in the CaIdwell view. (C) This Waters projection was made after surgical reduction and fixation of the fragments. Volume 4, Number 4 July 1984 RadioGraphics 641

66 Facial fractures Dolan et al. VI Complex Fractures Complex facial injuries are either bilateral on imply severe comminution of several parts of the facial bone complex. This category of injury is here divided into two groups: the LeFort and the smash types of fracture. LeFORT INJURIES Rene LeFort was a French surgeon who studied severe facial injury extensively and identified three basic forms of facial injury in the laboratory. (His articles have been translated into English by Tilson, McFee and Soudah.) From his experimental work, LeFort described three planes of weakness in the facial bones. Subjected to certain types of traumatic force, the facial bones tend to fracture along one on more of these planes. Separation at the fracture site results in the formation of a large, complex detached fragment that is unstable. Because of its instability, the position of such a detached fragment may become altered relative to its site of origin. Treatment is directed at stabilizing the upper jaw in a functional position. LeFont s planes of weakness are outlined in Figure 48. He originally described the craniofacial separation as the first plane of weakness and the transmaxillary plane as the last. For some reason, unknown to us, customary contemporary usage describes the transmaxillary fracture as the LeFort I and the craniofacial separation as the LeFort III fracture. To avoid confusion, we will use the contemporary usage. Figure 48A 642 RadioGraphics July 1984 Volume 4, Number 4

67 Dolan et al. Facial fractures LeFORT INJURIES Figure 48B Figures 48A & B The LeFort planes of weakness (A) This anteroposterior view corresponds to a CaIdwell projection. (B) Lateral view. Volume 4, Number 4 July 1984 RadioGraphics 643

68 Facial fractures Dolan et al. A. THE LeFORT I FRACTURE The LeFont I plane of weakness traverses both medial and lateral walls of the maxillary sinuses. Posteriorly, the pterygoid processes of the sphenoid are interrupted. This results in a floating palate fragment. Often, the maxillary dental arch will be in the anterior open bite position. This implies that the maxillary molars are approximated to the mandibular molar teeth, whereas the maxillary and mandibulan incisors are separated. It is suggested that one begin evaluation of a LeFont injury with inspection of the lateral view. This allows evaluation of the ptenygoid processes and posterior maxillary walk In Figure 49A, the ptenygoid processes are interrupted. Similarly, the walls of one zygomatic recess have been fractured. An anterior maxillary fracture separation is also present, and there is a slight anterior open bite. The transmaxillary fracture is best seen in the Waters view, Figure 49B. This also shows the anterior open bite and extension of the fracture through the inferior portion of the left zygomatic recess. Restoration of dental structure position was accomplished with interdental wines. Further stabilization was produced by suspension wines placed through drill holes in the bodies of the zygomas as seen in Figure 49C. The suspension wires were attached to the interdental wines below. This brings the movable maxillary fragment into optimal position with respect to the stable portion of the maxilla as shown in Figure 49C. Figure 49A 644 RadioGraphics July 1984 Volume 4, Number 4

69 Dolan et al. Facial fractures A. THE LeFORT I FRACTURE Figure 49B Figures 49A, B & C LeFort I fracture (A) This lateral view shows pterygoid process fractures at A, zygomatic recess fractures at B, and an anterior maxillary surface fracture at C. (B) In a Waters view transmaxillary fractures are seen (arrows). (C) This Waters view was obtained after surgical reduction and suspension of the fragments. Figure 49C Volume 4, Number 4 July 1984 RadioGraphics 645

70 Facial fractures Dolan et al. B. THE LeFORT II FRACTURE The LeFont II fracture illustrated by Figure 50A has interrupted the pterygomaxillary contices. Slight posterior displacement of the palatal fragment is present. The margins of the zygomatic recesses of both maxillary sinuses have been interrupted and comminution in the nasal-ethmoidal area is present. A slight anterior open bite position of the dental structures is evident. Downward displacement of the pyramidal fragment is illustrated by the Waters view in Figure 50B. The nasal arch and underlying glabella are fractured. Both inferior orbital borders are interrupted. A step-off is present on the night, whereas, less displacement is present on the left. Both lateral maxillary sinus walls are fractured at the inferior zygomatic margin and at the junction between the lateral maxillary wall and the dental alveolus. Both lateral orbital walls and zygomatic arches are intact. The right frontal process of the maxilla is comminuted and notated off the axis so that it is not seen in this view ( disappearing fragment sign). The left frontal process is in good position, but is separated from the medial maxillary sinus wall. The left orbital floor has been fractured and is displaced downward into the upper maxillary sinus. All of these features reflect that the force application was oven the nasal arch, a little to the right of the midline, and was directed obliquely downward and posteriorly in order to produce the resulting position of the main fragment. After reduction and fixation of the orbital rim and nasofrontal fractures, the application of an arch ban and interdental wining, the resulting fragment position is almost anatomic as seen in Figure 50G. Slight caudal displacement of the left orbital floor remains. The surgeon chose to loop the suspension wire over the zygomatic arch on the night, while the left suspension wire was placed through the arch. Figure 50A 646 RadioGraphics July 1984 Volume 4, Number 4

71 Dolan et al. Facialfractures B. THE LeFORT II FRACTURE Figure 50B Figures 50A, B & C LeFort II fracture (A) A lateral view shows pterygoid process fractures at A, zygomatic recess fractures at B and a nasal-ethmoidal fracture at C. Note the posterior position of the hard palate and slight anterior open bite. (B) This Waters view shows the pyramidal fragment produced by the multiple fractures (arrows). (C) This Waters view shows the result obtained with surgical reduction and fixation of the fragments. Figure 50C Volume 4, Number 4 July 1984 RadioGraphics 647

72 Facial fractures Dolan et al. C. THE LeFORT III FRACTURE The true LeFort III fracture is very uncommon as an isolated injury. Fracture through this plane more commonly occurs as a unilateral part of the LeFort Il-tripod injury which will be described below. The LeFort III fracture may occur in association with severe skull injury, however. The patient whose injury is demonstrated in Figure 51 had a severe head injury which produced a temporopanietal fracture extending across the middle cranial fossa and sella. The blow also has resulted in a left mandibular ramus fracture for which interdental wining had already been performed before the nadiographs were obtained. The lateral view in Figure 51A (and detail in Figure 51B) shows the temporoparietal and tnanssellan components of the injury. Though partial reduction has occurred, the pterygomaxillary interruption is still evident (arrow). Because of brain injury, only a table-top, antenoposterion Waters projection could be obtained. This view, Figure SiC, demonstrates a shift of the facial structures to the reader s left. An interrupted nasal arch is present and both zygomatic arches are fractured just in front of the glenoid fossae. The inferior orbital rims and lateral maxillary sinus walls are intact. A table-top antenopostenion view in the Caldwell position is illustrated by Figure 51D. In this, a lange left upper orbital rim fragment is present and is notated slightly clockwise. The nasal-ethmoidal fracture is evident centrally. On the right, a zygomaticofrontal suture sepanation is present along with a perpendicular separation of the lateral orbital wall. Shift of the upper facial fragment to the reader s left is again evident. Thus, the entire facial superstructure has been detached from its cranial attachments and has been displaced in position. Figure 51A Figure 51B 648 RadioGraphics July 1984 Volume 4, Number 4

73 Dolan et al. Facial fractures C. THE LeFORT III FRACTURE Figure 51C Figures5lA,B,C&D LeFort Ill fracture (A & detail B) The lateral view shows an extensive temporoparietal (small arrow) and transsphenoid fracture (arrowhead). There is a pterygoid process fracture indicated by the large arrow. (C) A tabletop anteroposterior Waters view demonstrates interruption of the nasal arch and fractures of the zygomatic arches (arrows). (D) A table-top anteroposterior Caldwell view shows an upper orbital rim fragment at A, and a nasal-ethmoidal fracture at B, as well as suture separation and a lateral orbital wall fracture at C. Figure 51D Volume 4, Number 4 July 1984 RadioGraphics 649

74 Facial fractures Dolan et al. C. THE LeFORT III FRACTURE Tomography is advised for the study of the details of LeFort injury patterns. Figure 52A is a tomognam that shows a longitudinal hand palate fracture and right frontal fracture complicating a LeFont II injury pattern. Comminution of the left inferior orbital rim and lateral maxillary wall are also present. If the presence on location of the pterygoid process fracture is not evident on plain films, tomography may be helpful. The patient whose radiograph is illustrated in Figure 52B had bilateral ptenygoid process fractures associated with a LeFont II injury. The injury shown in Figure 52C was thought to represent a LeFont II injury on plain films. The tomognaphic study demonstrates that the fracture pattern is actually a LeFort I with a large fragment involving the left frontal process of the maxilla. The night nasal and orbital bonders are intact on the tomognaphic study. Tomography may also help to define orbital apex and optic canal injuries as we have seen in earlier examinations. Figure 52A 650 RadioGraphics July 1984 Volume 4, Number 4

75 Dolan et al. Facial fractures C. THE LeFORT III FRACTURE Figure 52B Figures 52A, B & C Tomographyas an adjunct means of evaluating LeFort injuries (A) This anteroposterior tomogram shows a hard palate fracture at A, and a right frontal fracture at B complicating a LeFort II injury. (B) This tomogram shows pterygoid process fractures (arrows) that were not evident on plain views. (C) This patient sustained a LeFort I fracture, but a large left frontal process fragment (arrows) resembled a LeFort II fracture on plain films. Figure 52C Volume 4, Number 4 July 1984 RadioGraphics 651

76 Facial fractures Dolan et al. D. LeFORT FRACTURE VARIATIONS 1. The LeFort 11-Tripod Fracture Complex We have illustrated in Figure 52C that large fragment LeFort injuries need not be symmetrical. This asymmetry is the principal variation in LeFont injury forms and may assume any night sided and left sided variation. These variations result from variations in the size and shape, dinection and velocity of the injuring surface that comes into contact with the face. Perhaps, one of the most frequent variations is the fracture in which a LeFort II fragment and a tripod fragment are produced by the same injury. This form of fracture must be produced only by a very great force, inasmuch as severe comminution is present at points of impact. These fractures usually result from motor vehicle accidents and must result from the application of greater force than LeFont was able to apply in his studies, for he did not describe this combination of injuries among his induced fractures. The Waters view in Figure 53A shows marked comminution in the left nasal-ethmoidal area and along the left lateral maxillary sinus bonder. On the right, the inferior orbital rim and lateral maxillary sinus wall are separated in the LeFont II plane. This produces the central pyramidal fragment. In addition, there is a left tripod fragment that results from separation of the zygomaticofnontal suture and lateral orbital wall; the zygomatic arch is fractured near the glenoid fossa. The tripod fragment is displaced toward the patient s left side while the LeFont fragment is displaced to the night. Thus, in the LeFort Il-tripod designation, the radiologist must call the attention of the surgeon to the two principal fragments that require stabilization. A second aspect of this fracture is the severe frontal on ethmoidal roof injury that frequently accompanies the LeFont Il-tripod injury. In the lateral view, Figure 53B (and detail 53C), the posterior maxillary and ptenygoid process fractures are seen as are fractures of the zygomatic recess margins. Air-fluid levels are present in the high parasagittal region of the panietal area. This finding implies dural laceration with air escaping from a sinus cavity. If one carefully evaluates the lateral view, one finds no evidence of the ethmoidal roof. This reflects severe injury to the central portion of the anterior cranial fossa. A Caidwell view of this patient gives supplementary information regarding the nasal arch comminution, shows the left lateral orbital wall fracture and confirms the intracranial location of the air. Figure 53A 652 RadioGraphics July 1984 Volume 4, Number 4

77 Dolan et al. Facial fractures Figure 53B Figure 53C Figures 53A, B, C & D A LeFort Il-tripod fracture (A) This Waters view shows comminution of the nasal arch and left maxillary border. There are fractures in the LeFort II plane on the right at the vertical arrows. A left tripod fracture is mdicated by the horizontal arrows. (B) The upper arrows are on intracranial air-fluid levels; the lower arrows mdicate an ethmoidal roof (fovea) defect. (C) This detail of B demonstrates pterygoid process fractures (arrows) and zygomatic recess fractures (arrowheads). (D) A Caldwell views shows nasal arch comminution, a left lateral orbital wall fracture and intracranial air (arrows). Figure 53D Volume 4, Number 4 July 1984 RadioGraphics 653

78 Facial fractures Dolan et al. D. LeFORT FRACTURE VARIATIONS 2. The LeFort li-lefort III Fracture Complex If the point of impact in a complex injury is above the nasal arch area, the propagation of force may be along the LeFort III plane as seen in Figure 54. The force, in this case, was applied oven the left frontal, left zygomatic and left mandibular area (Figure 54A). A right-sided fracture in the LeFort III plane of weakness is also seen. An Erich arch ban with interdental wining spans an oblique horizontal namus mandibular fracture, which is not visible on this view. This complex of fractures has produced a large facial fragment and would be designated as a LeFont Ill-right, a LeFort Il-left, plus a left tripod fragment as well. The proximal portion of the left zygomatic arch has also been sheared off through the glenoid fossa. The right inferior orbital rim is intact in both the Waters view and the Caldwell view illustnated by Figure 54B. The large tnansfnontal fracture is also better seen in this view, as is the bilateral zygomaticofrontal suture separation. A view of this patient after reduction and fixation is shown in Figure 54C. Wire sutures maintain the left orbital rim fracture. Zygomaticofrontal suture fixation has been achieved and incorporated with suspension wines, which are attached to surface buttons for easier removal after the suspension wines are no longer needed. An external T-shaped splint protects the frontal fracture. While this fracture is clearly along the LeFort III plane of weakness on both sides, it would be insufficient to designate the fracture as such, for this would fail to call attention to the inferior orbital rim and lateral maxillary wall fractures on the left. Hence, the use of the more comprehensive term LeFont Il-tripod for the injury on the left. Figure 54A 654 RadioGraphics July 1984 Volume 4, Number 4

79 Dolan et at. Facial fractures Figure 54B Figures 54A, B & C Complex fracture consisting ofa ieft LeFort 11-tripod and right LeFort ill interruption (A) This Waters view shows a large fragment resulting from a right LeFort Ill fracture (vertical arrows) and a left LeFort II fracture (oblique arrows). A left tripod fragment is also present (O- ). An Erich arch bar spans the mandibular teeth. (B) The Caldwell view defines the transfrontal (arrows) and zygomaticofrontal suture separation (short arrows) better. (C) This Waters view was obtained after surgical reduction and fixation. Figure 54C Volume 4, Number 4 July 1984 RadioGraphics 655

80 Facial fractures Dolan et at. E. SMASH FRACTURE This categorical term is used to imply injury from the application of great force producing rather complete comminution of all the facial structures. The term is usually modified to describe the pontion of the face primarily involved. We use the following terms: nasal-ethmoidal smash; frontal smash; or central facial smash to describe the three major forms of this injury. The use of the term smash also implies that associated injury of the underlying pants of the skull is likely. Thus, in the case of the nasal smash injury, one would expect ocular, orbital apex and ethmoidal roof injury. Similarly, the frontal smash injury implies an interruption of the frontal sinus walls and strongly suggests underlying dunal and brain injury. In these forms and in the central facial smash, the middle cranial fossa is injured, along with the sphenoidal sinus walls. Rarely, the accompanying basal skull fracture will extend into the temporal bone and produce facial, auditory or vestibulan nerve injury. Patients with a smash injury usually have not only accompanying skull trauma, but axial on peripheral skeletal injury as well. Because of the patient s unstable general condition or skeletal injury, it is usually not possible to obtain more than a table-top facial bone x-ray examination. Tomography may be a very helpful supplemental examination and CT becomes very useful for facial analysis and brain evaluation. Figure 55A is the Waters view of a patient with a nasal-ethmoidal smash injury. In this, the nasal pyramid bonders are hardly recognizable and fractures through each of the vertical and horizontal facial buttresses are present. The Caldwell view of this patient in Figure 55B further illustrates the nasal-ethmoidal comminution and reveals a small left frontal sinus air-fluid level. Bilateral zygomaticofrontal suture separation is present. Figure 55A 656 RadioGraphics July 1984 Volume 4, Number 4

81 Dolan et at. Facialfractures E. SMASH FRACTURE Figure 55B Figure 55A & B Nasal-ethmoidal smash injury(a) The multiple fractures of this complex injury are seen here in the Waters view. (B) This is a Caldwell view of the same patient. See text for description of the findings. Volume 4, Number 4 July 1984 RadioGraphics 657

82 Facialfractures Dolan et at. E. SMASH FRACTURE A frontal smash injury is shown in Figure 56. The frontal sinus walls were comminuted and had been decompressed by the time a lateral view, Figure 56A, could be obtained. Ethmoidal roof interruption and an opaque sphenoidal sinus are also evident in this view. Figure 56B is a table-top antenoposterion view of the same patient. All of the facial buttresses have been interrupted. Figure 56C is a postenoantenion view after reduction and fixation of the fragments. Obvious distortion of the frontal sinus, nasal arch and left orbit persists. Patients who sustain such devastating injury often require extensive cosmetic surgical repair. Figure 56A 658 RadioGraphics July 1984 Volume 4, Number 4

83 Dolan et at. Facial fractures Figure 56B Figures 56A, B & C Frontalsmash injury(a) This lateral view was obtained after surgical fixation of a fracture involving the antenor wall of the frontal sinus. It shows multiple fractures some of which are indicated with arrows. (B) The multiple fractures are here demonstrated in a table-top anteroposterior Waters view. (C) The extent of the injury is better demonstrated in this postoperative Waters view. Figure 56C Volume 4, Number 4 July 1984 RadioGraphics 659

84 Facial fractures Dotan et at. E. SMASH FRACTURE Only emergency survey antenopostenion and lateral views were available to illustrate the plain film findings of the central facial smash injury shown in Figure 57A. This frontal view, shows extensive frontal and night orbital comminution. The lateral facial view (Figure 57B) demonstrates complete frontal, orbital roof and ethmoidal roof interruption, as well as comminution of all facial bones. An anteroposterior tomogram after frontal decompression and interdental wining is shown in Figure 57C. Comminution of the entire facial skeleton is present. Figure 57A 660 RadioGraphics July 1984 Volume 4, Number 4

85 Dolan et al. Facial fractures E. SMASH FRACTURE Figure 57B Figure 57C Figures 57A-57C Central facial smash injury (A) Extensive comminution of the facial structures is seen in this survey table-top anteroposterior view. (B) The survey lateral facial view shows almost complete destruction of normal landmarks. (C) The severe comminution of the facial bones is confirmed in this anterior facial tomogram. Volume 4, Number 4 July 1984 RadioGraphics 661

86 Facial fractures Dolan et at. E. SMASH FRACTURE Figure 57D is a transaxial tomognam through the midmaxitlany plane showing extensive comminution of the facial bones with posterior compressive displacement. The sinuses are opaque and air is present in the subcutaneous, retromaxillary and right panaphanyngeal areas. The nasopharynx is obscured by blood. A transonbital CT scan (Figure 57E) illustrates posterior displacement of the nasal arch and total facial bone disruption. Rupture of the left eye is demonstrated. Figure 57F is a transaxial CT scan through the frontal sinus. A depressed fracture is present just lateral to the night sinus bonder. An oblique fracture extends through the left frontal sinus and a deep cutaneous laceration is present just lateral to the left sinus. Figures 57D-F Central facialsmash injury(d) This transmaxillary CT scan made with window and level setting optimized for bone detail again shows severe comminution of the facial bones bilaterally. (E) This transorbital CT scan made with settings optimized for bone detail shows rupture of the left eye in addition to comminution of the facial bones. (F) This transfrontal CT scan (bone window) shows a depressed fracture on the right (arrowhead) and an oblique fracture through the frontal sinus on the left (arrow). 662 RadioGraphics July 1984 Volume 4, Number 4