Facial bone fractures an overview

Facial bone fractures: an overview
Dr. Ahmed M. Adawy
Professor Emeritus, Dept. Oral & Maxillofacial Surg.
Former Dean, Faculty of Dental Medicine
Al-Azhar University

The bone and soft tissues of the face are able to absorb the energy from impact forces. Force to the bone in the elastic range causing the deformation and after force removal, bone returns to its previous state, but if the force be greater than the elasticity of bone, a permanent displacement occurs and be irreversible. Furthermore, when these forces exceed the strength of these tissues, a variety of fractures can occur. The buttress theory proposes that the midfacial region is like a framework that is stabilized by horizontal and vertical buttresses. The most common causes of maxillofacial trauma are traffic accidents, injuries from fights, sport accidents or falls. The Le Fort’s classification is based on low-velocity trauma, and does not completely reflect the breadth of high-velocity fractures encountered in modern practice. Currently, facial fractures are classified into central midface fractures, lateral midface fractures and mandibular fractures. Nasal, nasoethmoidal, Zygomatic bone, and orbital fractures are presented. Today, surgical techniques have been moving away from delayed closed reduction with internal wires suspension to early open reduction and internal plate fixation. Different treatment approaches exist to restore the facial skeleton using the different facial buttresses as landmarks.

1. Facial bone fractures: an overview Dr. Ahmed M. Adawy Professor Emeritus, Dept. Oral & Maxillofacial Surg. Former Dean, Faculty of Dental Medicine Al-Azhar University

2. Craniofacial skeleton The skull is composed of three principle bony structures: cranial vault, cranial base, and facial skeleton. The rigid cranial vault protects the brain from external injury. The brain rests on cranial base. This constitutes ‘‘neurocranium’’ (1)

3. Eight bones form the cranial vault: two parietal bones, two temporal bones, frontal bone, occipital bone, sphenoidal and ethmoidal bones Craniofacial skeleton

4. The facial skeleton can be divided for convenience into three parts; the upper third of facial skeleton being a part of cranial vault and comprising of frontal bone, the middle third comprising of central midfacial bone: the maxilla, the nasoethmoid, and lateral midfacial bone: zygoma, and the lower third comprising of rigid bone: mandible, with its condylar articulation to base of skull (1) Facial skeleton

5. Fifteen irregular bones form the facial skeleton: three singular bones lying in the midline; mandible, ethmoid, and vomer and six paired bones occurring bilaterally; maxilla, inferior nasal concha [turbinate], zygomatic, palatine, nasal, and lacrimal bones Facial skeleton

6. The facial skeleton constitutes with the oral cavity and other associated soft tissues, ‘‘viscerocranium’’. The facial skeleton is made up of a series of irregular flattened bones that (with exception of the mandible) is joined by static articulations called sutures. In adults, sutures are believed to function primarily as shock absorbers to dissipate stresses transmitted through the skull (2) Facial skeleton

7. Anatomically, the bones of the cranial vault and the mandible have a basic structure similar to many other bones of the skeleton with a strong outer cortex and a cancellous centre. In contrast, most of the bones of the midfacial region are comprised only of a thin layer of cortical bone and exhibit significant variations in their thickness and composition Facial skeleton

8. Thin, fragile mid-facial bones (3)

9. The bone and soft tissues of the midfacial region are able to absorb the energy from impact forces. Force to the bone in the elastic range causing the deformation and after force removal, bone returns to its previous state, but if the force be greater than the elasticity of bone, a permanent displacement occurs and be irreversible. Furthermore, when these forces exceed the strength of these tissues, a variety of fractures can occur at this region Facial bone fractures

10. Load-deformation curve

11. The characteristics of fractures resulting from trauma are determined by a dynamic factor (given by the force and energy of the impact) and by a static factor (given by the anatomic characteristics of the bone involved). A small impact area results in a localized fracture, whereas a large impact area leads to more extensive indirect fractures, because the force is being transmitted over a larger area of bone (4) Facial bone fractures

12. According to geometry of face, protruding areas are most likely to sustain injury. Thus the nasal bones are most commonly injured, followed by malar bones, orbital rims, and symphysis of the mandible. The area of the frontal bone is most resistant to injury. As fracture occurs energy absorption takes place, thus protecting the brain from violent deceleration Facial bone fractures

13. The buttress theory Facial bone fractures

14. The buttress theory proposes that the midfacial region is like a framework that is stabilized by horizontal and vertical buttresses. These buttresses believed to absorb considerable amount of traumatic energy approaching the midface region from below. However, the midface has very low tolerance to impact forces applied from other directions, with nasal bones exhibiting the least resistance (5) Facial bone fractures

15. Biomechanical load distribution along facial buttresses

16. The nasal bones were the most fragile of the facial bones, with tolerance levels for minimal fracture in the 25–75 Nm range . The maxilla displayed low tolerance level in the range of 150–300 Nm. The relatively fragile zygomatic arch displayed tolerance levels between 200 and 400 Nm, whereas the body of the zygoma displayed a higher tolerance level with a grouping in the 200–650 Nm range. The massive frontal bone displayed the highest tolerance levels with grouping between 800 and 1600 Nm Facial bone fractures

17. Forces (Nm) required to fracture the facial skeleton ( 5)

18. Interesting to note that the bite forces in healthy middle-aged humans averages 520 Nm for males and 340 Nm for females. However , maximal forces have produced up to the high 700s Facial bone fractures

19. Facial bone fractures The buttresses represent areas of relative increased bone thickness that support both the functional units and the form of the face in an optimal relation, and forces directed toward the face are distributed along these buttresses. Facial buttresses can be classified into vertical and horizontal buttresses (5)

20. The vertical buttresses are: the nasomaxillary buttress (connections between the maxilla and nasal bones), the zygomaticomaxillary buttress (from the maxilla to the zygomatic region), the pterygomaxillary buttress (from the maxilla to the pterygoid process) and the posterior or mandibular buttress (ascending ramus of the mandible) Facial bone fractures

21. Vertical buttresses : nasomaxillary , zygomaticomaxillary, pterygomaxillary , and vertical mandibular

22. The horizontal buttresses include: ( 1) frontal bar, ( 2 ) transverse zygomatic buttress, (3 ) transverse maxillary buttress, ( 4) upper transverse mandibular buttress, (5) lower transverse mandibular buttress Facial bone fractures

23. Horizontal buttresses include the frontal, zygomatic , maxillary and mandibular buttresses

24. The most common causes of maxillofacial trauma are traffic accidents, injuries from fights, sport accidents or falls. The combination of traffic accidents and injuries from fights account for 80% of maxillofacial fractures ( 6) . The force of impact can be derived from the equation F = ma (7) , where: Force = mass ( weight) × acceleration ( speed ) Facial bone fractures

25. Egypt leads the Middle East when it comes to road accidents, with an average of 12,000 people killed annually

26. In such an overcrowded area, interpersonal violence remains a major problem

27. Around the turn of the 19th into the 20th centuries, René Le Fort, a French surgeon, conducted a series of experiments using human cadavers to study facial bone fractures resulting from blunt trauma . The impacts included hitting the midface of a whole or decapitated cadaver with a baseball bat, and hitting the midface region onto a granite tabletop. He then cut the body segments open and studied the fractures they had sustained (8) Facial bone fractures

28. He concluded that midface fractures occurred through ‘lines’ of inherent weakness in the facial skeletal structure, producing defined injury patterns . The fracture patterns were predictable and reproducible, depending on the site of impact on the midface. He then formulated a classification system still extensively used today: the Le Fort classification. Common to these fractures is involvement of the pterygoid plates Facial bone fractures

29. The Le Fort I fracture extends horizontally across the maxilla above the level of the roots of the teeth, traversing the lower lateral walls of the pyriform aperture and the lower nasal septum. It extends posteriorly across the lateral, medial and posterior walls of the maxillary sinus and involves the pterygoid plates. Unique to Le Fort I fracture is the involvement of the lateral walls of the pyriform aperture Facial bone fractures

30. Le Fort I fracture

31. The Le Fort II fracture is pyramidal, with the apex at the naso-frontal suture. From the apex, the fracture line extends inferolaterally through the medial wall of the orbit, orbital floor, inferior orbital rim and through the zygomatico-maxillary suture. It also extends posteriorly to the pterygoid plates. Unique to Le Fort II fractures is involvement of the inferior orbital rim Facial bone fractures

32. Le Fort II fracture

33. The Le Fort III fracture, also known as cranio-facial disjunction, is like the Le Fort II, and comprises dissociation of the naso-frontal suture. However, this is horizontally oriented, traversing the medial and lateral walls of the orbits, the zygomatico-frontal suture and the zygomatic arch. Involvement of the latter is unique to type III fractures (9) Facial bone fractures

34. Le Fort III fracture

35. Le Fort fractures. Three-dimensional CT images of an adult skull in frontal and lateral orientations with color overlays show the osseous facial structures that are typically affected by type I (red), type II (blue), and type III (yellow)

36. Although useful in describing a midface fracture, Le Fort’s classification i s based on low-velocity trauma, and does not completely reflect the breadth of high-velocity fractures encountered in modern practice . In addition, it underestimate the complexity of facial fracture patterns, which often include combination of front-orbital, zygomatic, and nasoethmoidal fractures with maxillary injury. Moreover, it does not define the facial skeletal supports or the more severely comminuted fractures Facial bone fractures

37. Currently, facial fractures are classified into central midface fractures , lateral midface fractures and mandibular fractures . Central midface fractures include: nasal, nasoethmoidal , orbital wall, maxillary sinus, Le Fort I, and Le Fort II fractures. Lateral midface fractures include fractures of the zygomatic-malar complex, zygomatic arch, and orbital floor fractures. While Le Fort III fractures are combined central and lateral midface fractures. In another way, facial bone fractures are classified as isolated or complex fractures Facial bone fractures

38. In a series of multi-trauma patients with over 7,000 facial bone fractures, 24.3 % affected the mandible and 71.5% affected the central and lateral midface. Almost one third of fractures simultaneously affected more than one area of the face (10) Facial bone fractures

39. In another study comprising 2,094 cases with facial bone fractures (11) , the most common isolated fracture site was the nasal bone (37.7%), followed by the mandible (30%), orbital bones (7.6%), zygoma (5.7%), maxilla (1.3%) and the frontal bone (0.3%). The largest group with complex fractures included the inferior orbital wall and zygomaticomaxillary (14%) Facial bone fractures

40. Nasal Fractures Nasal fractures are the most common facial fractures, accounting for 50% of isolated fractures of the face (12). Any fracture that involves the nasal bones, septum, or the nasal process of the maxillary process is considered a nasal fracture. Symptoms may include bleeding, swelling, bruising, and an inability to breathe through the nose. They may be complicated in complex pattern by other facial fractures

41. Nasal fractures

42. Nasoethmoidal fractures Nasoethmoidal fractures occurred at a frequency of 7%. These fractures most often result from a frontal blow over the bridge of the nose , and the nasal pyramid is displaced posteriorly , fracturing the nasal bones, frontal processes of the maxillae, lacrimal bones, ethmoid sinuses, cribriform plate, and nasal septum. In patients with comminution, the bony segments may spread medially into the nasal cavity , superiorly to the anterior cranial fossa, and laterally into the orbit. CSF leaks should be suspected

43. Nasoethmoidal fractures

44. Zygomatic bone fracture Zygomatic bone fracture is the second most common midfacial injury, following nasal fracture. A zygomatic complex fracture is characterized by separation of the zygoma from its four articulations ( frontal, sphenoidal , temporal, and maxillary). An independent fracture of the zygomatic arch is termed an isolated zygomatic arch fracture

45. Zygomatic bone fracture

46. Isolated zygomatic arch fracture

47. Orbital fractures Because of the complex anatomy of the region , orbital fractures are often associated with maxillary, zygomatic and/or nasal fractures. Isolated orbital fractures can be classified as ‘blow-out’ or ‘blow-in’. Most blow-out fractures affect the anteroinferomedial aspect of the orbital cavity and displace the orbital globe posteromedially and inferiorly. A significant increase in the volume of the orbital cavity results in herniation of the orbital floor and globe to the maxillary sinus. Less often, fracture segments can herniate upward into the orbit, which is called blow-in fracture (13)

48. Orbital blow-out fracture

49. Panfacial fractures Panfacial fractures result from high-energy mechanisms such as motor vehicle collisions and gunshot wounds. There are higher chances of cervical spine and cerebral injuries with these fractures compared to the other facial fractures. The upper, middle, and lower faces need to be involved to be labeled as panfacial fracture (14)

50. Panfacial fractures

51. Clinical examination and computed tomography imaging are the gold standards in the diagnosis, planning, and management of facial fractures (15) Facial bone fractures

52. Significant advances have occurred during the last two decades in the methods of fixation used for facial bone fractures, resulting in improved functional and aesthetic outcomes . Surgical techniques have been moving away from delayed closed reduction with internal wires suspension to early open reduction and internal plate fixation Facial bone fractures

53. Miniplates and screws for fixation of facial bone fractures

54. The transition from wire osteosynthesis to rigid internal fixation in craniofacial reconstruction using different micro or mini-plates and screw systems is regarded as one of the greatest advances in the field of maxillofacial surgery. The high degree of ductility in these microplate screw fixation systems permits an optimal adaptation to the thin facial bone and provides three-dimensional stability (16) Facial bone fractures

55. Interesting to note that plating of fractures began in 1895 when Lane first introduced a metal plate for use in internal fixation (17) . Lane’s plate was eventually abandoned owing to problems with corrosion. Today, the use of miniplates provides the principal modality of treatment for reduction and fixation of displaced facial fractures. Titanium plates and screws are considered the “gold standard” to immobilize displaced fracture segments Facial bone fractures

56. Lane’s plate. Please note the design and morphology of the plate . The plate shows a four holes and is retained by mono cortical screws (18)

57. The main limitation with plate fixation is the larger surgical exposure required and greater profile (thickness) of the plate beneath the soft tissue . The conventional fixation of osteosynthesis plates requires areas of sufficient cortical bone mass to insert screws. This may be difficult to achieve at sites where the boney structures is very thin and can cause further fractures due to the force applied to the fragments (19) Facial bone fractures

58. The face has relatively little soft tissue to provide coverage to hardware from the outer surface. It is therefore not surprising that palpable/ prominent plates and screws are one of the common complications in craniofacial procedures. The sliding of the overlying soft tissue of the face over the hardware can result in erosion, infection and subsequent exposure of the fixation devices. Large size hardware has a larger tendency toward eroding the overlaying tissue (20) Facial bone fractures

59. The use of biodegradable implants, glues and adhesive for fracture fixation has potential to overcome many of the problems associated with microplate screw fixation systems. However, to date, substances with adhesive properties for bone gluing purposes are limited due to bad biocompatibility, high infection rates and lack of sufficient adhesive stability (21) Facial bone fractures

60. The principle aim of these devices and techniques is to reconstruct the pre-traumatic facial appearance, including the facial width, projection, and height (22) . The restoration of the normal function of the facial structures is another aim in facial fracture management. Modern therapy also mandate the rigid stabilization of the vertical and horizontal facial buttress to withstand the forces of mastication Facial bone fractures

61. Different treatment approaches exist to restore the facial skeleton using the different facial buttresses as landmarks. The frontal bar defines the contour of the upper third of the face. The inferior orbital rim and malar prominence define the width and projection of the midface. The maxillary alveolus and piriform aperture provide the platform for nasal reconstruction Facial bone fractures

62. Re-establishment of these buttresses is essential for the maintenance of midface height, width, and projection . Reconstruction can be done in a “bottom up & inside out” or “top down & outside in” (23) . The occlusion gives a reference for the width and the vertical and horizontal planes. Starting from a stable area to an unstable one is advocated Facial bone fractures

63. In spite of the advancement in the different types of technologies and methods of bone fixation, clinicians continue to experience complications and challenging reconstruction conditions. Several authors reported an overall complication rate among craniofacial procedures between 14% and 22 % (24,25) . Infection is one of the most commonly encountered problem, and is one of the main causes for removal of maxillofacial internal fixation hardware Facial bone fractures

64. Nonunion or malunion usually results from failure to either adequately reduce disparate fracture fragments or not establishing adequate bone-to-bone contact. This can result in excessive motion between the bone segments and cause tissue rupture in the forming callus and / or hardware failure. Mobility of the bone fragments can cause numerous problems such as malocclusion and diplopia (26,27) . As such, but even so, we are still far from ideal Facial bone fractures

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