Facial Trauma, Zygomatic Complex Fractures

HISTORY

Fractures of the face and mandible have been recognized for a long time, and attempts to treat such fractures have been recorded as far back as 25-30 centuries BC. The Smith Papyrus is perhaps the first document in which treatment modalities of several types of zygomatic fractures are described and suggested.

Zygomatic fractures were not brought to the spotlight in the literature again until 1751, when du Verney described the anatomy, type of fractures of the zygoma observed, and his approach to reduction in two case reports. Recognizing the importance of reduction for proper healing, du Verney took advantage of the mechanical forces of the masseter and temporalis muscles on the zygoma in a unique approach to closed reduction techniques.

In 1906, Lothrop was the first to describe an antrostomy approach in which he reached the fractured zygoma through the Highmore antrum below the inferior turbinate. He then was able to rotate the fractured zygoma upward and outward for a proper reduction. This transantral approach is known today as the Caldwell-Luc approach. This method avoids external incisions while giving access to the maxillary sinus for debridement of pulverized bone and mucosal debris and drainage.

In 1909, Keen categorized zygomatic fractures as those of the arch, the body, or the sutural disjunction. He was the first to describe an intraoral approach to the zygomatic arch in which an incision is made in the gingivobuccal sulcus.

In 1927, Gillies described an original approach to reduce a depressed malar bone. He was the first to reach the malar bone through an incision made behind the hairline and over the temporal muscle. Gillies further described the use of a small, thin elevator that is slid under the depressed bone, thus enabling the surgeon to use the leverage of the elevator to reduce the fracture. The Gillies method remains in use today to elevate the arch.

Adams recognized the need for greater stabilization in more comminuted fractures and was one of the first to write of internal wire fixation. This technique, described by Adams in 1942, remained the mainstay treatment at many institutions for years. A study performed by Dingman and Natvig demonstrated that many zygoma fractures treated with a closed reduction technique and then later re-examined were more severe than they had appeared clinically or by roentgenographic evaluation. It appeared that although the fracture was reduced at one point, the bone became displaced again due to extrinsic forces. Therefore, they concluded that most displaced fractures of the zygoma should be treated by open reduction and direct wire fixation.

Other advocates of internal wire-pin fixation were Brown, Fryer, and McDowell. In their publication in 1951, they described the use of Kirschner wires, either alone or in combination with direct wiring, for the purpose of stabilizing middle-third facial fractures.

Osteosynthesis became a reality for facial fractures in the 1970s. The Swiss AO group and Association for the Study of Internal Fixation developed miniplate fixation. The success of miniplates was supported further by Michelet et al and others, who continued to develop techniques for reduction and fixation of facial fractures using miniplates. For unstable, displaced fractures of the zygoma, miniplates were found to efficiently stabilize the bones with minimal complications. The complications noted were attributed to surgical technique rather than the plating system.

ANATOMIC CONSIDERATIONS

The integrity of the zygoma is well established as critical in the maintenance of normal facial width and prominence of the cheek. In addition, by making up the anterior lateral floor, it is a major contributor to the orbit. From a frontal view, the zygoma can be seen to articulate with 4 bones: medially by the maxilla, superiorly by the frontal bone, and posteriorly by the greater wing of the sphenoid bone within the orbit. From a lateral view, one clearly can see the temporal process of the zygoma join the zygomatic process of the temporal bone to form the zygomatic arch. Attached to the zygoma anteriorly are the zygomaticus minor and major muscles, as well as part of the orbicularis oculi muscle. Laterally, the masseter muscle from below attaches to the zygomatic arch and produces displacing forces on the zygoma.

Sicher and DeBrul were the first to depict facial anatomy in terms of structural pillars or buttresses. This concept allows consideration of an approach for reduction of midface fractures and ultimately the production of a stable reconstruction. Manson et al have elucidated this concept further by emphasizing the idea that the mid face is made of sinuses that are supported fully and fortified by vertical and horizontal buttresses of bone.

Three principle buttresses need to be considered in midface fractures. The medial or nasomaxillary buttress reaches from the anterior maxillary alveolus to the frontal cranial attachment. The second is the pterygomaxillary or posterior buttress, which connects the maxilla posteriorly to the sphenoid bone. The third is the lateral or zygomaticomaxillary buttress. This important buttress connects the lateral maxillary alveolus to the zygomatic process of the temporal bone. These buttresses help give the zygoma an intrinsic strength such that blows to the cheek usually result in fractures of the zygomatic complex at the suture lines, rarely of the zygomatic bone.

Fracture lines usually run through the infraorbital rim, involve the posterolateral orbit, and extend to the inferior orbital fissure. The fracture line then continues to the zygomatic sphenoid suture area and on to the frontozygomatic suture line. All zygomatic complex fractures involve the orbit, making visual complications a frequent occurrence.

Another important landmark with respect to zygomatic fractures is the sphenozygomatic junction (especially laterally displaced fractures). The alignment of the zygoma with the greater wing of the sphenoid in the lateral orbit is critical for determining adequate reduction of zygomatic fractures. Reducing the 3 points that make up the buttresses also helps ensure proper alignment of the zygoma and proper reduction of other facial fractures present. This graduated approach helps preserve facial height and width.

Lastly, the branches of the fifth and seventh cranial nerves live within the bounds of the mid face. Particularly the temporal and zygomatic branches of the seventh nerve and the zygomaticotemporal and zygomaticofacial branches of the fifth nerve must be elucidated carefully upon surgical dissection of the area to prevent complications of paresis and paresthesias, respectively.

CLASSIFICATION

In 1961, Knight and North proposed a new anatomically based classification system of zygoma fractures, which they hoped would help better determine the prognosis and treatment of such injuries. Group I encompassed fractures with no significant displacement as evidenced clinically and radiographically. While fracture lines may be seen, their recommendation was that this group requires no surgical intervention. A soft diet and careful avoidance of any further injury is prudent.

Group II fractures include only those of the arch caused by a direct blow that buckles the malar eminence inward. This fracture is often associated with trismus. Often, this type of fracture can be treated satisfactorily by a Gillies approach or other standard techniques.

Unrotated body fractures, medially rotated body fractures, laterally rotated body fractures, and complex fractures (defined as the presence of additional fracture lines across the main fragment) belong to groups III, IV, V, and VI, respectively. Knight and North defined these groups by their stability after reduction. They found that 100% of group II and group V fractures were stable after a Gillies reduction, and no fixation was required. However, 100% of group IV, 40% of group III, and 70% of group VI were unstable after reduction and required some form of fixation.

A study by Pozatek et al concurred with the findings of Knight and North except for group V fractures. They found this group to be unstable 60% of the time. Dingman and Natvig studied a number of patients who were treated by the usual closed methods of zygomatic elevation. In a significant number of patients, they found concomitant fractures along other suture lines and within the orbit after exposing the site through a brow or lower lid incision. They postulated that these fractures were overlooked because of the edema and hematomas present at the time of evaluation and reduction. Even more surprising, a significant number of patients suffered from redisplacement of the zygoma some time after reduction (with no fixation). This redisplacement may be caused by the displacing forces of the masseter, which are only truly offset by the temporalis fascia.

In a follow-up study, Lund found that all group III fractures were stable after reduction, a finding in much disagreement with that of Knight and North. It now seems apparent that displaced fractures require careful assessment and open reduction and fixation.

Manson and colleagues have proposed a more modern classification system in which CT scan is used as the backbone of assessing and classifying zygomatic fractures. CT provides abundant information about facial structures, including both bone segmentation and bone displacement, and allows the surgeon to appropriately address all aspects of the injury as needed. This system divides fractures into low-energy, medium-energy, and high-energy injuries.

Low-energy zygoma fractures demonstrate little or no displacement, with stability provided by an incomplete fracture. These types of fractures often are seen at the zygomaticofrontal suture, and their inherent stability usually does not justify a reduction. Middle-energy zygoma fractures demonstrate complete fractures at all buttresses, mild-to-moderate displacement, and a wide range of comminution. Often, an eyelid and intraoral exposure is necessary for adequate reduction and fixation. High-energy zygoma fractures frequently accompany Le Fort or panfacial fractures as a segment of these injuries. These fractures often extend through the glenoid fossa and permit extensive collateral and posterior dislocation of the arch and malar eminence. A coronal exposure, in addition to the oral and eyelid incisions, usually is necessary to correct the facial width and anterior projection of the malar eminence.

BIOMECHANICS

While 2-point fixation of zygomatic fractures may be used commonly, it often leaves an axis of rotation for the zygoma following an adequate reduction. Forces such as the masseter muscle often displace the zygoma postoperatively. Thus, making the diagnosis and then choosing the correct approach to establish 3-point fixation and ultimate stability is essential for obtaining a successful outcome. Since biomechanic properties are of primary importance underlying the treatment of zygoma fractures, a brief discussion is warranted.

Primary bone healing allows quicker and stronger healing of a fracture than callous healing. A study by Lin et al reported that rigidly fixated bone grafts maintain their position and volume better than mobile grafts. Furthermore, rigid fixation helps the bone heal by primary processes rather than by fibroelastic processes. In terms of postoperative stability of a reduced zygoma fracture, 3-point fixation is undoubtedly best. However, at times, 2-point stabilization is perfectly adequate.

Some biomechanical models predict downward, backward, and medial rotation of the zygoma with 2-point alignment. Furthermore, the superiority of miniplates over interfragmentary wiring is observed only when fewer points of fixation are used. In this study, the authors found that one miniplate could be used as effectively as 3 points of wire fixation. However, only 5 kg of force were used in the study (normal sustained forces of up to 50 kg are seen in vivo).

In a study by Rinehart et al, mechanical loads that better approximate the actual sustained forces observed physiologically were used. Deforming forces of this magnitude require at least two miniplates (with 1 miniplate stronger than 3 points of wire fixation and slightly weaker than 3 plates).

In a retrospective study by Rohrich et al, rigid miniplate fixation achieved consistently better malar and global symmetry than did interosseous wires. Furthermore, fewer complications occurred, including infraorbital nerve sensory abnormalities. Long-term experimental studies demonstrate that miniplates maintain the osseous volume of bone grafts and prevent nonunion at bone graft contact points better than wires. Rigid fixation with plates and screws is the best form of bony fixation; it restores 3-dimensional stability and allows for the least amount of motion between ends of fragments, the main cause of bone resorption and instability.

Presently, several types of microplating systems are available to choose from when rigid fixation is needed for stabilization. A recent study by Gosain et al directly compared titanium plates with biodegradable plate and screws and cyanoacrylate glue fixation systems. Titanium miniplates were the strongest in distraction and compression across a central gap.

However, in many situations, resorbable plates and screws are believed to be adequate. Such situations may include the presence of primarily compressive forces of relapse and sturdy bone fragments that can be fixed in direct contact, since forces of relapse are absorbed by bone fragments and not the fixation system. Resorbable plates and screw fixation systems can be used when standard titanium midface and microplate systems are believed to be adequate. Resorbable plates fixed with cyanoacrylate glue may be used if forces of relapse are primarily compressive and titanium midface or microplate and screw fixation systems are believed to be adequate.

APPROACHES

The approach to the fracture often depends not only on the location of the fracture but also on the exploration and stabilization required as anticipated by the surgeon.

Temporal and supraorbital approaches

When the fracture only entails depression of the malar arch with interference of the free movement of the mandible by pressure over the coronoid process, a temporal approach as described by Gillies can be used. This approach provides an effective means for surgically reducing a depressed zygomatic arch while leaving a minimal scar that often goes unnoticed behind the hairline.

The supraorbital approach, described by Dingman and Natvig in 1964, is also an excellent method to use for the reduction of zygomatic arch fractures. Furthermore, the incision at the lateral aspect of the eyebrow provides exposure of the area around the frontozygomatic suture. However, the methods mentioned above often do not allow for optimal direct visualization of the reduced arch and potentially result in inadequate repair.

Studies by Kobienia et al of intraoperative portable fluoroscopy have demonstrated improved results with the use of a Gillies/temporal or supraorbital approach for arch fractures. This technique allows visualization of the arch and confirmation of fracture reduction, while decreasing the need for postoperative CT scan in patients with isolated zygomatic arch fractures.

Gingivobuccal sulcus incision

The zygoma also may be accessed through a gingivobuccal sulcus incision. Through this incision, acute comminuted fractures and malunited fracture-dislocations can be treated. Achieve wide exposure of the anterior maxilla and zygoma by extending the periosteal elevation laterally, carefully avoiding the infraorbital nerve and vessels.

Transconjunctival approach

When the repair of the fracture requires exposure of the orbital floor and rim (transconjunctival approach), both preseptal and retroseptal dissection planes have been described. This technique, introduced by Dr P Tessier in 1973, has proven be an excellent approach for the exposure of the orbital floor and inferior rim. The main advantage to this technique is the lack of visible scar. This technique is believed to be underused because of concern regarding the inadequate exposure and higher postoperative complication rates, including lower eyelid shortening and ectropion. However, a recent review and study of this technique has demonstrated that this approach is indeed safe and effective in patients who have not undergone a previous transconjunctival incision.

Open reduction

Comminuted fractures, such as those often seen in mid-energy and high-energy fractures, necessitate open reduction. For the exposure of anterior buttress articulations of the zygoma, two exposures can be used. First, a lower eyelid subciliary approach can be used. For this approach, make an incision parallel to the fold of the lower eyelid; this allows exposure of the rim of the orbit, the infraorbital nerve, and the area of junction between the zygoma and maxilla. Additionally, an intraoral exposure of the articulation of the zygoma with the maxillary alveolus can be used for reduction of mid-energy fractures. Confirmation of reduction requires simultaneous visualization of the multiple anterior articulations of the zygoma, looking for symmetry of the forward and lateral projections of the mid face. Thus, stable zygomatic arch reconstruction is extremely important for facial symmetry and structural support of a reconstructed mid face.

Coronal exposure

High-energy injuries, often seen in car crashes, result in extensive posterior and lateral dislocation of the malar eminence and posterior and inferior depression of the zygomatic body. A coronal exposure is often required to align the malar eminence and correct facial width. Alignment of the sphenoid wing allows for good confirmation of anatomic reduction of the arch and malar eminence.

Coronal incisions with careful dissection allow for the prevention of postoperative morbidities related to damage to the frontal branch of the facial nerve, atrophy of the temporalis muscle, and displacement of the lateral canthal ligament resulting in downward inclination of the lateral canthus. The use of a coronal incision allows for temporary interosseous wiring of the frontozygomatic fracture site. The anteroposterior displacement of the zygomatic body then can be rotated into place, checking alignment of the lateral orbital wall, inferior orbital rim, and zygomaticomaxillary buttress, and fixed with miniplates and screws. Furthermore, the malar arch at this time can be reconstructed and repaired with a plate and screw system.

Endoscopically assisted operations

As an alternative to coronal incisions for the repair of zygomatic arch and orbital floor fractures, endoscopically assisted operations have been investigated. Lee et al have found that the advantage of this approach is the reduction in complications traditionally seen in the coronal incision (eg, facial nerve injury, alopecia, external scarring, ectropion, eyelid edema). Initial cadaveric studies first demonstrated that it is possible to use this technique to effectively repair comminuted fractures of the zygomatic arch with complete preservation of the frontal branch of the facial nerve. In clinical studies, preauricular incision sites are used to allow for access and visualization, and miniplate and screw systems are used for repair. If desired, a transverse lateral orbital incision may be made to assess the adequacy of the reduction.

An approach to the infraorbital rim via an intraoral incision is believed to be as easy as the former approaches mentioned but the creation of a lower incision is felt to be worth the time and effort required. Perhaps the benefits of endoscopically repaired fractures will decrease the need and complications observed with coronal incisions traditionally used for comminuted fractures.

COMPLICATIONS

Infraorbital nerve dysfunction

Fractures of the zygomatic complex frequently result in sensory disturbances in the infraorbital nerve distribution. These symptoms include dysesthesia of the skin of the nose, cheek, lower eyelid, upper lip, gingiva, and teeth of the affected side. These arise because fractures generally occur in the vicinity of the infraorbital foramen and canal. This incidence can range from 50-94% with long-term dysfunction of 20-50%, depending on the technique of sensory measurement. Several authors (eg, Taicher et al, 1993; DeMan and Bax, 1988; Vriens et al, 1998) have noted significant improvement in sensory function after open reduction and internal fixation with plates versus a closed reduction technique. This does not make infraorbital nerve dysfunction after a nondisplaced zygoma fracture a sole indication for exploration and decompression since sensory function returns in most patients.

Trismus

Trismus is also a common finding (45%), particularly after a fracture involving the zygomatic arch. It results from impingement upon the coronoid process of the mandible by a depressed zygomatic arch. This may indicate a need for elevation of the depressed arch, accurate reduction, and fixation. If new bone has formed in the space below the zygomatic arch and restricts the movement of the mandible, an intraoral approach for coronoidectomy may be required to permit mandibular movement.

Diplopia

Diplopia may occur after zygoma fractures for a number of reasons. These include but are not limited to hematoma, muscle injury, motor nerve injury to the extraocular muscles, entrapment of extraocular muscles, or damage to the fine connective tissue system described by Koornneef. In Ellis et al's series of 2067 zygomatico-orbital fractures (1985), diplopia was noted in approximately 12% of patients. Diplopia that occurs after zygoma fractures not associated with significant orbital floor fractures and entrapment is usually transitory and probably associated with hematomas. Barclay reported an 8.4% incidence of diplopia; 60% were transitory.

A symptomatic diplopia associated with a positive forced duction test and CT evidence of entrapped muscle or soft tissue with no improvement over 1-2 weeks may be an indication for surgery. When diplopia is associated with enophthalmos, an improvement in vision can be predicted after correction of the enophthalmos. Diplopia associated with zygomatico-orbital fractures may persist longer, and young patients may recover more slowly than adults.

Enophthalmos

A study of over 1000 patients by Zingg et Al (1992) demonstrated a 3-4% incidence of acute enophthalmos. The eye is supported by intramuscular cone fat, a network of intraorbital ligaments, and the bony orbit. The displacement of orbital contents into an enlarged bony orbit with subsequent change to a more spherical orbital soft-tissue shape is thought to be the principle underlying mechanism behind the development of enophthalmos. The most common causes of enophthalmos include the failure to properly reduce displaced zygoma fractures and malunited zygoma fractures. Blow-out fractures of the orbit, especially those of the medial wall and those of floor fractures behind the axis of the globe, and high-velocity comminuted fractures involving combinations of lateral wall, posterior floor, and medial wall fractures are other causes of enophthalmos. Other theories of possible causes of enophthalmos include fat atrophy, soft-tissue contracture, and fibrosis.

Before surgical correction of enophthalmos, examine the patient to assess visual function, extraocular eye movement, and the sensory function of the infraorbital nerve. Both thin coronal and axial slices on CT scans are helpful in determining the extent of orbital damage.

Infection

While an infrequent occurrence, infection is a problem that threatens all postoperative patients. A study by Zachariades et al of 223 patients treated with rigid internal fixation of facial bone fractures reported that interosseous wiring resulted in a greater rate of infection when compared to bone plates. While 4.5% of patients suffered from both late and early infection, only .8% of infections were located in the mid face. Sinusitis has been found to be the most common type of infection seen in postoperative patients but preseptal cellulitis and dacryocystitis also can occur.

Complications with plates and/or screws

Since microplate development in the late 1980s, wire fixation techniques have been used less in zygoma fractures. However, no matter how well these plates and screws work, occasions exist where their removal is required. The usual cause is a palpable plate although a pain syndrome may occur. More rarely, infections may occur. Very rarely, screws can fracture into bone and create problems for removal. These problems may be limited by a broad availability of drill sizes for use in thin or dense bone. In a review of 55 patients who had internal fixation devices removed after many types of craniomaxillofacial surgery, including trauma, Orringer et al found palpable plates and screws to be the most common reason (35%), followed closely by pain, infection, or loosening of the fixation device (approximately 25%). The authors' experience with complications of fixation of zygoma fractures is limited mainly to palpable plates and screws at the frontozygomatic suture and infraorbital rim.

REFERENCES

• Arechiga H, Yanagisawa K. Inhibition of visual units in the crayfish. Vision Res. Apr 1973;13(4):731-44. [Medline].
• Barclay TL. Diplopia in association with fractures involving the zygomatic bone. Br J Plast Surg. 1958;11:47.
• Brand G, Dreesen W, Wangerin K. [Timing of the surgical management of zygomatic fractures]. Fortschr Kiefer Gesichtschir. 1991;36:85-6. [Medline].
• Brown JB, Fryer MP, McDowell F. Internal wire-pin stabilization for middle third facial fractures. Surg Gynecol Obstet. 1951;93:676.
• Converse JM, Smith B. Enophthalmos and diplopia in fractures of the orbital floor. Br J Plast Surg. 1957;9:265.
• Cope MR, Moos KF, Speculand B. Does diplopia persist after blow-out fractures of the orbital floor in children?. Br J Oral Maxillofac Surg. Feb 1999;37(1):46-51. [Medline].
• Davidson J, Nickerson D, Nickerson B. Zygomatic fractures: comparison of methods of internal fixation. Plast Reconstr Surg. Jul 1990;86(1):25-32. [Medline].
• De Man K, Bax WA. The influence of the mode of treatment of zygomatic bone fractures on the healing process of the infraorbital nerve. Br J Oral Maxillofac Surg. Oct 1988;26(5):419-25. [Medline].
• De Man K. Orbitabodemfracturen. Thesis. Rotterdam:. Erasmus University;1982.
• Dingman RO, Natvig P. Surgery of Facial Fractures. Philadelphia:. WB Saunders Co;1964.
• Ellis E, el-Attar A, Moos KF. An analysis of 2,067 cases of zygomatico-orbital fracture. J Oral Maxillofac Surg. Jun 1985;43(6):417-28. [Medline].
• Gillies HD, Kilner TP, Stone D. Fractures of the malar-zygomatic compound: With a description of a new x-ray position. Br J Surg. 1927;14:651-6.
• Gosain AK, Song L, Corrao MA, Pintar FA. Biomechanical evaluation of titanium, biodegradable plate and screw, and cyanoacrylate glue fixation systems in craniofacial surgery. Plast Reconstr Surg. Mar 1998;101(3):582-91. [Medline].
• Grant MP, Iliff NT, Manson PN. Strategies for the treatment of enophthalmos. Clin Plast Surg. Jul 1997;24(3):539-50. [Medline].
• Gruss JS, Mackinnon SE. Complex maxillary fractures: role of buttress reconstruction and immediate bone grafts. Plast Reconstr Surg. Jul 1986;78(1):9-22. [Medline].
• Gruss JS, Van Wyck L, Phillips JH, Antonyshyn O. The importance of the zygomatic arch in complex midfacial fracture repair and correction of posttraumatic orbitozygomatic deformities. Plast Reconstr Surg. Jun 1990;85(6):878-90. [Medline].
• Jungell P, Lindqvist C. Paraesthesia of the infraorbital nerve following fracture of the zygomatic complex. Int J Oral Maxillofac Surg. Jun 1987;16(3):363-7. [Medline].
• Karlan MS, Cassisi NJ. Fractures of the zygoma. A geometric, biomechanical, and surgical analysis. Arch Otolaryngol. Jun 1979;105(6):320-7. [Medline].
• Keen WW. Surgery: Its Principles and Practice. Philadelphia:. WB Saunders;1909.
• Knight JS, North JF. The classification of malar fractures: An analysis of displacement as a guide to treatment. Br J Plast Surg. 1961;13:325.
• Kobienia BJ, Sultz JR, Migliori MR, Schubert W. Portable fluoroscopy in the management of zygomatic arch fractures. Ann Plast Surg. Mar 1998;40(3):260-4. [Medline].
• Koornneef L. Current concepts on the management of orbital blow-out fractures. Ann Plast Surg. Sep 1982;9(3):185-200. [Medline].
• Koornneef L. Spatial Aspects of the Orbital Musculofibrous Tissue in Man. Amsterdam and Lisse: Swets and Zeitinglinger;1977.
• Kruger GO. Textbook of Oral Surgery. 3rd ed. St. Louis: CV Mosby Co;1968:269.
• Lang W. Traumatic Enophthalmos with retention of perfect acuity of vision. Trans Ophthalmol Soc UK. 1889;9:41.
• Lee C, Jacobovicz J, Mueller RV. Endoscopic repair of a complex midfacial fracture. J Craniofac Surg. May 1997;8(3):170-5. [Medline].
• Lee CH, Lee C, Trabulsy PP, et al. A cadaveric and clinical evaluation of endoscopically assisted zygomatic fracture repair. Plast Reconstr Surg. Feb 1998;101(2):333-45; discussion 346-7. [Medline].
• Lin KY, Bartlett SP, Yaremchuk MJ, et al. The effect of rigid fixation on the survival of onlay bone grafts: an experimental study. Plast Reconstr Surg. Sep 1990;86(3):449-56. [Medline].
• Longaker MT, Kawamoto HK. Enophthalmos revisited. Clin Plast Surg. Jul 1997;24(3):531-7. [Medline].
• Longaker MT, Kawamoto HK. Evolving thoughts on correcting posttraumatic enophthalmos. Plast Reconstr Surg. Apr 1998;101(4):899-906. [Medline].
• Lothrop HA. Fractures of the superior maxillary bone caused by direct blows over the malar bone. Boston Med Surg. 1906;154:8.
• Lund K. Fractures of the zygoma: a follow-up study on 62 patients. J Oral Surg. Aug 1971;29(8):557-60. [Medline].
• Lyon DB, Newman SA. Evidence of direct damage to extraocular muscles as a cause of diplopia following orbital trauma. Ophthal Plast Reconstr Surg. 1989;5(2):81-91. [Medline].
• Manson PN, Hoopes JE, Su CT. Structural pillars of the facial skeleton: an approach to the management of Le Fort fractures. Plast Reconstr Surg. Jul 1980;66(1):54-62. [Medline].
• Manson PN, Crawley WA, Yaremchuk MJ, et al. Midface fractures: advantages of immediate extended open reduction and bone grafting. Plast Reconstr Surg. Jul 1985;76(1):1-12. [Medline].
• Manson PN, Markowitz B, Mirvis S, et al. Toward CT-based facial fracture treatment. Plast Reconstr Surg. Feb 1990;85(2):202-12; discussion 213-4. [Medline].
• Manson PN, Clifford CM, Su CT, et al. Mechanisms of global support and posttraumatic enophthalmos: I. The anatomy of the ligament sling and its relation to intramuscular cone orbital fat. Plast Reconstr Surg. Feb 1986;77(2):193-202. [Medline].
• Manson PN, Grivas A, Rosenbaum A, et al. Studies on enophthalmos: II. The measurement of orbital injuries and their treatment by quantitative computed tomography. Plast Reconstr Surg. Feb 1986;77(2):203-14. [Medline].
• Mathog RH, Archer KF, Nesi FA. Posttraumatic enophthalmos and diplopia. Otolaryngol Head Neck Surg. Jan 1986;94(1):69-77. [Medline].
• McCarry B, Fells P, Waddell E. Difficulties on the management of orbital blow-out fractures in patients under 20 years old. In: Ravault AP, Lock M, eds. Transactions of the 5th International Orthoptic Congress. Lyon: LIPS. 1987;283-7.
• McCoy FJ, et al. An analysis of facial fractures and their complications. Plast Reconstr Surg. 1962;29:381.
• McDonald S:. '. Personal Communication.
• Michelet FX, Deymes J, Dessus B. Osteosynthesis with miniaturized screwed plates in maxillo-facial surgery. J Maxillofac Surg. Jun 1973;1(2):79-84. [Medline].
• O''Hara DE, DelVecchio DA, Bartlett SP, Whitaker LA. The role of microfixation in malar fractures: a quantitative biophysical study. Plast Reconstr Surg. Feb 1996;97(2):345-50; discussion 351-3. [Medline].
• Orringer JS, Barcelona V, Buchman SR. Reasons for removal of rigid internal fixation devices in craniofacial surgery. J Craniofac Surg. Jan 1998;9(1):40-4. [Medline].
• Pearl RM. Treatment of enophthalmos. Clin Plast Surg. Jan 1992;19(1):99-111. [Medline].
• Pozatek ZW, Kaban LB, Guralnick WC. Fractures of the zygomatic complex: an evaluation of surgical management with special emphasis on the eyebrow approach. J Oral Surg. Feb 1973;31(2):141-8. [Medline].
• Rahn BA. Theoretical considerations in rigid fixation of facial bones. Clin Plast Surg. Jan 1989;16(1):21-7. [Medline].
• Rinehart GC, Marsh JL, Hemmer KM, Bresina S. Internal fixation of malar fractures: an experimental biophysical study. Plast Reconstr Surg. Jul 1989;84(1):21-5; discussion 26-8. [Medline].
• Rohrich RJ, Watumull D. Comparison of rigid plate versus wire fixation in the management of zygoma fractures: a long-term follow-up clinical study. Plast Reconstr Surg. Sep 1995;96(3):570-5. [Medline].
• Rohrich RJ, Hollier LH, Watumull D. Optimizing the management of orbitozygomatic fractures. Clin Plast Surg. Jan 1992;19(1):149-65. [Medline].
• Rowe NL, Killey HC. Fractures of the Facial Skeleton. Edinburg E & Livingston, Ltd;1955.
• Sicher H, DeBrul EL. Oral Anatomy. 5th ed. St. Louis: Mosby;1970:78.
• Spiessl B. Rigid internal fixation of fractures of the lower jaw. Reconstr Surg Traumatol. 1972;13:124-40. [Medline].
• Taicher S, Ardekian L, Samet N, et al. Recovery of the infraorbital nerve after zygomatic complex fractures: a preliminary study of different treatment methods. Int J Oral Maxillofac Surg. Dec 1993;22(6):339-41. [Medline].
• Vriens JP, van der Glas HW, Bosman F, et al. Information on infraorbital nerve damage from multitesting of sensory function. Int J Oral Maxillofac Surg. Feb 1998;27(1):20-6. [Medline].
• Vriens JP, van der Glas HW, Moos KF, Koole R. Infraorbital nerve function following treatment of orbitozygomatic complex fractures. A multitest approach. Int J Oral Maxillofac Surg. Feb 1998;27(1):27-32. [Medline].
• Watumull D, Rohrich RJ. Zygoma fracture fixation: A graduated approach to management and biomechanical studies. Problems of Plastic and Reconstructive Surgery. 1(2):1991.
• Wiesenbaugh JM Jr. Diagnostic evaluation of zygomatic complex fractures. J Oral Surg. Mar 1970;28(3):204-8. [Medline].
• Wojno TH. The incidence of extraocular muscle and cranial nerve palsy in orbital floor blow-out fractures. Ophthalmology. Jun 1987;94(6):682-7. [Medline].
• Yanagisawa E. Symposium on maxillo-facial trauma. 3. Pitfalls in the management of zygomatic fractures. Laryngoscope. Apr 1973;83(4):527-46. [Medline].
• Zachariades N, Papavassiliou D, Papademetriou I. The alterations in sensitivity of the infraorbital nerve following fractures of the zygomaticomaxillary complex. J Craniomaxillofac Surg. Oct 1990;18(7):315-8. [Medline].
• Zachariades N, Papademetriou I, Rallis G. Complications associated with rigid internal fixation of facial bone fractures. J Oral Maxillofac Surg. Mar 1993;51(3):275-8; discussion 278-9. [Medline].
• Zingg M, Laedrach K, Chen J, et al. Classification and treatment of zygomatic fractures: a review of 1,025 cases. J Oral Maxillofac Surg. Aug 1992;50(8):778-90. [Medline].
• de Man K, Wijngaarde R, Hes J, de Jong PT. Influence of age on the management of blow-out fractures of the orbital floor. Int J Oral Maxillofac Surg. Dec 1991;20(6):330-6. [Medline].