You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > TRAUMA Maxillary Zygomatic FracturesArticle Last Updated: May 1, 2007AUTHOR AND EDITOR INFORMATIONAuthor: E Bradley Strong, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, University of California at Davis E Bradley Strong is a member of the following medical societies: Alpha Omega Alpha and American Rhinologic Society Editors: Michael Mercandetti, MD, MBA, FACS, Consulting Staff, Department of Surgery, Doctors Hospital of Sarasota; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Erik Kass, MD, Chief, Department of Clinical Otolaryngology, Associates in Otolaryngology of Northern VA; Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders; Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Author and Editor Disclosure Synonyms and related keywords: zygomaticomaxillary complex, zygomaticomaxillary complex fracture, ZMC, ZMC fracture, upper jaw bone, upper jaw, jaw, broken jaw, os zygomaticum, zygomatic bone, cheek bone, cheekbone, broken cheek bone, broken cheekbone INTRODUCTIONThe zygomaticomaxillary complex (ZMC) plays a key role in the structure, function, and aesthetic appearance of the facial skeleton. It provides normal cheek contour and separates the orbital contents from the temporal fossa and the maxillary sinus. It also has a role in vision and mastication. The ZMC provides lateral globe support necessary for binocular vision. The zygomatic arch is the insertion site for the masseter muscle and protects the temporalis muscle and the coronoid process. The frequency of ZMC fractures is second only to nasal fractures, which are the most common type of facial fracture (Donald, 1976). The prominent convex shape of the zygoma makes it vulnerable to traumatic injury. Even minimally displaced ZMC fractures can result in functional and aesthetic deformities. Successful repair of ZMC fractures requires an accurate diagnosis, appropriate surgical exposure, and precise reduction to reconstitute the complex 3-dimensional anatomy. For excellent patient education resources, visit eMedicine's Back, Ribs, Neck, and Head Center, Breaks, Fractures, and Dislocations Center, and Eye and Vision Center. Also, see eMedicine's patient education articles Broken Jaw, Facial Fracture, and Black Eye. ProblemSee Clinical. FrequencyA much higher percentage of ZMC fractures occur in males (80%) than in females (20%). Incidence of ZMC fractures peaks in persons aged 20-30 years. EtiologyThe most common causes of ZMC fractures include personal altercations, falls, motor vehicle accidents, and sports injuries. Other associated facial fractures occur in 25% of patients who sustain ZMC fractures (Ellis, 1985). PathophysiologySee Relevant Anatomy for a discussion of the impact of ZMC fractures on other facial structures. Classification Many authors have devised classification schemes for ZMC fractures (Ellis, 1985; Yanagesawa, 1973; Knight, 1961). Zingg (1992) separates these injuries into types A, B, and C. Type A injuries are isolated to one component of the tetrapod structure, including the zygomatic arch (type A1), the lateral orbital wall (type A2), and the inferior orbital rim (type A3). Type B fractures involve all 4 buttresses (ie, classic tetrapod fracture). Type C injuries are complex fractures with comminution of the zygomatic bone itself. These classification schemes are of little clinical significance; however, they are helpful in research and physician communication. Type A fractures are relatively uncommon. Type B and C fractures account for 62% of ZMC injuries (Ellis, 1985). Types B and C fractures most commonly occur at the zygomaticomaxillary and zygomaticotemporal buttresses. The zygomaticofrontal buttress is the strongest of the 4 ZMC buttresses. Significant disruption at this site usually implies a high velocity injury with comminution in other areas. The weakest bone of the ZMC complex is the orbital floor. Types A3, B, and C injuries result in orbital floor disruption, which places the orbital contents at risk. ClinicalThe initial evaluation of facial trauma patients is focused on areas that can result in the greatest morbidity. Airway control and hemodynamic stability are the primary concerns. Next, spinal cord injury must be ruled out by a thorough clinical and/or radiological examination. Finally, any overt globe injury should be evaluated. After the patient has been stabilized, a thorough history can be taken and physical examination can be performed. A complete head and neck examination will reveal most bony or soft tissue injuries. When ZMC fractures are identified, an ophthalmologic consultation should be obtained. The most common symptoms associated with ZMC fractures include pain, edema, and ecchymosis of the cheek and eyelids. Malar flattening and palpable periorbital step-offs, often occur. The traumatic force and pull of the masseter muscle may result in medial, inferior, and posterior rotation of the zygoma (Jackson, 1989). Trismus (ie, reduced jaw mobility) may result from compression of the zygomatic arch on the temporalis muscle and coronoid process. Orbital floor disruption can result in subcutaneous emphysema. Infraorbital nerve injury may result in anesthesia or paresthesias of the cheek, nose, upper lip, and lower eyelid. Jelks (1987) reported a 14-40% incidence of significant intraocular injury in patients with ZMC fractures that involved the orbital floor. For this reason, preoperative ophthalmology consultation is essential in patients with orbital floor injuries. Disruption of the bony orbit often results in expansion of the orbital volume and herniation of orbital contents. Inferior (hypophthalmos) and posterior (enophthalmos) globe displacement both occur. Extraocular muscle contusion or entrapment may result in diplopia. Upward gaze diplopia is most common, secondary to entrapment of the inferior rectus muscle and soft tissue surrounding it. However, any of the extraocular muscles may be involved. Comparing forced-duction tests on each eye can help to identify the specific site of muscle entrapment. This study is much easier to perform under general anesthesia. Evaluation of unanesthetized patients is often difficult because of poor patient cooperation. Compression of the orbital contents occurs less frequently. These injuries result in decreased orbital volume and displacement of the globe both superiorly (hyperophthalmos) and anteriorly (exophthalmos). These injuries are associated with an increased risk of optic nerve injury and visual loss. Physical findings such as severe conjunctival hemorrhage or hyphema are suggestive of direct globe injury, rupture, and visual loss. INDICATIONSSurgical intervention is indicated in patients with injuries that result in a significant cosmetic or functional deformity, such as the following:
RELEVANT ANATOMYThe malar eminence is the most prominent portion of the ZMC and is located approximately 2 cm inferior to the lateral canthus. The malar eminence corresponds to the central portion of the ZMC. From this central position, 4 bony attachments to the skull are evident, namely, a superior attachment to the frontal bone (frontozygomatic suture line), a medial attachment to the maxilla (zygomaticomaxillary suture line), a lateral attachment to the temporal bone (zygomaticotemporal suture line), and a deep attachment to the greater wing of the sphenoid bone (zygomaticosphenoidal suture line) (Strong, 1998). Some authors describe the zygomaticomaxillary and zygomaticosphenoidal suture lines as a single unit. Using this definition, ZMC fractures are called tripod fractures. However, the term tetrapod fracture is a more accurate description because 4 suture lines are disrupted. The term ZMC fracture describes a spectrum of injuries that includes nondisplaced fractures, fractures displaced at an isolated buttress, and severely comminuted fractures with bone loss. Information about the degree and severity of the overall injury can be extrapolated from the location of the fractures. The frontozygomatic and zygomaticosphenoidal buttresses are very strong. Isolated injuries in these areas are uncommon. When displaced fractures are noted, a high velocity injury with other associated fractures is likely. The inferior orbital rim is a common location for displaced and comminuted fractures. These injuries can be isolated, but they are often associated with orbital floor fractures. The zygomaticomaxillary buttress is commonly disrupted and associated with V2 paresthesias. Isolated injuries often occur in the zygomatic arch because of its length and unprotected location. CONTRAINDICATIONSContraindications to surgical repair of ZMC fractures include medical instability and globe injuries. Orbital exploration in the presence of a hyphema or ruptured globe can result in exacerbation of the injury. WORKUPImaging Studies
Other Tests
Diagnostic Procedures
TREATMENTMedical therapyPatients with a nondisplaced or minimally displaced ZMC fracture and normal findings on ophthalmologic examination can be treated conservatively. Medical management includes a soft diet, analgesia, and close follow-up care. Surgical therapyThe ultimate goal in treating ZMC fractures is to obtain an accurate stable reduction while minimizing external scars and functional deformity. These goals are accomplished more easily several days after the injury, when much of the tissue edema has resolved and any residual deformity can be appreciated more readily. After induction of general endotracheal anesthesia, the surgeon should evaluate any existing lacerations that may be used for fracture reduction or application of plates and screws. Common surgical approaches to the ZMC buttresses include sublabial, lateral orbit, lower eyelid, and scalp incisions. These incisions should be used in a hierarchical fashion starting with the sublabial incision. The sublabial incision is well camouflaged and is associated with minimal morbidity, including mild trigeminal paresthesias. It can be used to reduce and plate the zygomaticomaxillary buttress (and, at times, the inferior orbital rim). Lateral orbital incisions are indicated for those fractures that cannot be adequately reduced and fixated via the sublabial approach. Lower eyelid incisions are well hidden but can result in postoperative lower eyelid malposition and corneal exposure (entropion or ectropion). They should generally be reserved for moderately-to-severely displaced fractures requiring exposure of 3 buttresses for adequate repair (obviously, an isolated, comminuted, inferior orbital rim fracture will likely require a lid incision for repair). Finally, for severely comminuted ZMC fractures with disruption of the zygomatic arch, a coronal scalp incision is required. Scalp incisions are associated with little morbidity, but often result in apparent scars and scalp anesthesia. As a general rule, the surgeon should continue to expose the fracture until adequate reduction is obtained and functionally stable fixation can be achieved. Zygomaticomaxillary buttressThe zygomaticomaxillary buttress is commonly fractured in tetrapod injuries. Use a transverse buccal sulcus incision to expose this area. The incision is well hidden, results in no external scar, and exposes the entire face of the maxilla. Incise the mucosa 1.5-2 cm above the gingiva using guarded electrocautery. This technique facilitates wound closure. Carry the incision from the midline to the second maxillary molar and extend as necessary. Take care to avoid entering the buccal fat pad posteriorly because this will result in fat prolapse, which obscures the surgical field. After the fracture is carefully reduced, apply an L-shaped 2-mm miniplate to fixate the ZMC to the palate. Apply at least 2 screws on each side of the fracture. Finally, irrigate the wound with antibiotic solution and close it with running, locking, 3-0 chromic suture. Frontozygomatic buttressWith more severe injuries, the frontozygomatic buttress is usually the second buttress to be exposed. Comminution at this site is uncommon, and fractures can often be reduced and plated through a limited incision (Stanley, 1989). Although a visible scar results, incisions at this site are well hidden and associated with little morbidity. The 3 most common approaches to the frontozygomatic buttress are the lateral upper lid blepharoplasty, lateral brow, and hemicoronal incisions. Lateral upper lid blepharoplasty A lateral upper lid blepharoplasty incision provides excellent access to the frontozygomatic suture line with better aesthetic results than the lateral brow incision. Mark a 2- to 3-cm skin incision in a natural crease on the lateral third of the upper eyelid. Then, retract the eyelid skin laterally over the frontozygomatic suture line. Incise the skin and orbicularis oculi muscle with a scalpel. Place retractors in the incision to lateralize the upper lid soft tissue over the frontozygomatic buttress. This protects the lacrimal gland or orbital fat. The levator aponeurosis is quite thin laterally and at low risk for injury. Use a guarded needlepoint electrocautery to incise the edematous subcutaneous tissue and periosteum exposing the fracture. After the fracture is reduced, apply a 5-hole, 1.5- to 1.7-mm, low profile miniplate. Irrigate the wound with antibiotic solution, and close the subcutaneous tissues and orbicularis oculi muscle with 3-0 resorbable suture. Close the skin with interrupted 6-0 monofilament nonabsorbable suture, which is removed 5-7 days after the operation. Tissue glue can also be used for skin closure; however, extra caution must be used to avoid contact with the globe. Lateral brow incision The lateral brow incision is time tested and has been used by many surgeons. However, it has few if any advantages over the upper eyelid approach described above and results in a higher risk of visible postoperative scaring, alopecia of the lateral eyebrow, or both. Place the incision within or just below the lateral brow and carry it onto the frontozygomatic buttress (described above under blepharoplasty incision). Meticulous closure of the incision with eversion of the soft tissues will optimize the postoperative result. Hemicoronal incision The hemicoronal incision provides wide surgical exposure to the zygoma and frontal bone. Indications for this approach include superior orbital rim fractures and comminuted fractures of the ZMC, including the zygomatic arch. When possible, this approach should be avoided in patients with male pattern baldness. Prior to incision, part or shave the hair between the vertex and the superior helical root. Place the incision at least 5 cm behind the hairline. A zigzag or "w" pattern can be used to help camouflage the incision. This is most effective in patients with straight hair that falls over the suture line. If necessary, the incision can be extended across the midline for additional exposure. After injection with local anesthetic, incise the skin with a scalpel, starting at the vertex and moving toward the helical root. Carry the incision through the galea aponeurosis, leaving the pericranium and temporalis muscle fascia (deep temporal fascia) intact. Apply Raney clips to control blood loss. Special care must be taken to avoid injury to the temporal branch of the facial nerve that lies in the temporoparietal fascia (superficial temporal fascia). The galea aponeurosis elevates easily from the pericranium. Use careful blunt dissection to elevate the temporoparietal fascia free from the temporalis muscle fascia. Join the 2 dissection planes sharply at the temporal line. The incision can be carried across the midline to the contralateral ear for more exposure or for access to the frontal sinus and orbital rims. To expose any fracture of the frontozygomatic buttress or orbital rim, the periosteum can be incised and elevated. Alternatively, the pericranium can be incised at the vertex with the skin incision and carry out the entire central dissection in a subperiosteal plane. If there is any risk of frontal sinus or nasoorbitoethmoid injury, maintain the pericranial flap intact for possible closure of CSF leaks. Reduce the fractures and apply 1.5- to 1.7-mm miniplates. Using resorbable monofilament sutures, resuspend the soft tissues to the flap and the temporalis muscle fascia. This reduces the risk of postoperative ptosis of the facial soft tissues. Close the galea aponeurosis with a 3-0 resorbable polyglycolic suture and the scalp with staples. Leave a 0.25- inch Penrose drain in place for 24 hours, and apply a pressure dressing for 3-5 days. Infraorbital buttressThe orbital rim, transconjunctival, and subciliary incisions are three common surgical approaches to the orbital rim. An endoscopic approach may also be useful. Orbital rim incision Position a 3- to 4-cm incision directly over the bony orbital rim approximately 1.5-2.0 cm below the lower lid margin. Carry the incision directly through the skin, orbicularis oculi muscle, subcutaneous tissue, and periosteum. While this approach is faster than eyelid incisions and is associated with minimal risk of postoperative eyelid malposition, it results in a visible cutaneous scar and can be associated with lower eyelid edema. Consequently, most surgeons avoid this incision except in patients with significant rhytids and minimal concerns of an external scar. Transconjunctival approach This approach requires a thorough understanding of lower eyelid anatomy. The technique offers a well-concealed incision, has a low risk of lower lid ectropion, and provides excellent exposure to the orbital rim and floor (Zingg, 1991, 1992; Lynch, 1974;Tessier, 1973; Converse, 1973; Tenzel, 1971). The dissection can be performed in a preseptal or postseptal (retroseptal) plane. For a preseptal approach, place a corneal shield over the globe. Inject a small amount (0.5-1.0 mL) of local anesthetic into the conjunctival incision line. The incision runs along the inferior border of the tarsal plate between the punctum and the lateral commissure. Place two 6-0 silk retraction sutures through the gray line of the lower eyelid and retract them inferiorly to expose the palpebral conjunctiva. Use a guarded needlepoint or bipolar cautery to gently cauterize the incision site. Incise the mucosa and the capsulopalpebral fascia just below the tarsal plate with a number 15 blade. Place a 6-0 retraction suture through the free inferior margin of the palpebral conjunctiva. Retract the free margin superiorly over the globe to expose the dissection plane. Carry the dissection inferiorly between the orbital septum (deep) and the orbicularis oculi muscle (superficial) along an avascular plane. Once a small pocket has been formed, use a Sewall retractor to gently elevate the globe and a Desmarres retractor to depress the lower eyelid. Take care to keep the orbital septum intact, and avoid exposure of orbital fat or injury of the inferior oblique muscle. Once the orbital rim periosteum is exposed, use a guarded-needlepoint cautery to expose the bony rim and fracture. A periosteal elevator can then be used to raise the orbital floor periosteum and evaluate the extent of any orbital blowout fracture. Handle the periosteal edges carefully and keep them intact to assist with the closure. Repair large orbital blowout fractures with an onlay graft covering the orbital defect and resting securely on a stable rim of bone at the periphery of the defect. Take great care to view the posterior aspect of the defect and insert the implant onto the posterior shelf of orbital floor bone (see endoscopy). Implant materials may range from calvarial bone, septal/auricular cartilage, or porous polyethylene. Nonporous materials such as silicone sheeting are more prone to migration, infection, and extrusion. When greater medial or posterior orbital exposure is anticipated, a lateral canthotomy and cantholysis can be performed. Before the lower lid conjunctival incision, place a scalpel or scissor on the lateral commissure. Initiate the canthotomy at the junction of the upper and lower lids and carry it approximately 5 mm laterally. Place the incision in a crows-foot wrinkle, if present. Placing anterior traction on the raw surface of the lower lid exposes the inferior crus of the lateral canthal tendon. Then use scissors to sever this tendon close to the bony insertion. When adequate mobility is achieved, the lower lid freely moves away from the globe. Then complete the dissection as previously described. Once the orbital rim fractures are completely exposed, the injuries are reduced and plated with 1.0- to 1.3-mm microplates. Caution must be used to avoid catching periorbital fat on the drill shaft. A 5-hole miniplate is used with isolated fractures. For comminuted injuries, longer plates are required. In these instances, the reduction is approximated with a central defect, and the plate is applied. The small intervening segments then are lagged up to the plate, reapproximating their premorbid location. The surgeon must be aware that this adds a certain level of error into the reduction. Confirm accurate reduction of the other buttresses before application of the spanning plate. Repair of the orbital floor should be delayed until the anterior orbital rim fractures have been reduced. Reduction of the rim fractures provides landmarks for the anterior margin of the orbital floor and a stable ledge for fixation of any implant. After all fractures are repaired, close the periosteum over the orbital rim with 5-0 resorbable sutures. Reapproximate the palpebral conjunctiva with running 6-0 fast-absorbing gut sutures. A 5-0 polydioxanone suture on a half round needle is then passed through the lateral free edge of the tarsal plate. The suture is then passed (from deep to superficial) through the periosteum overlying the lateral orbital tubercle of Whitnall. Make an attempt to place this suture high and slightly on the internal surface of the superior orbital rim. A 6-0 fast-absorbing gut suture then is placed to reapproximate the gray line of the superior and inferior lids. The suture is left long and tethered laterally under the first skin sutures. Interrupted 6-0 nylon sutures are used to reapproximate the skin. The primary advantages of this approach include a hidden scar and protection of the periorbita inferior oblique muscle. A theoretical disadvantage of the preseptal approach includes a slightly increased risk of lower lid malposition (when compared to the retroseptal approach) because the orbicularis oculi muscle is elevated from the orbital septum. The postseptal (retroseptal) approach directly exposes the orbital rim through the orbital fat pad. It involves placement of a Sewall elevator in the fornix to elevate the globe superiorly and a Desmarres retractor to depress the lower lid. The conjunctiva is incised, and the orbital rim is exposed directly through the orbital fat. This technique is very rapid because it does not require meticulous dissection of the orbital septum. This reduces the risk of postoperative lower lid ectropion. However, the lack of dissection planes during the retroseptal approach increases the risk of inferior oblique muscle injury. Reduction and plating can also be more difficult secondary to the prolapse of orbital fat into the surgical field. Fracture reduction and repair are completed as described above. The conjunctival incision is closed with 6-0 fast absorbing gut sutures. Subciliary approach Inject local anesthetic into the lower eyelid skin 2 mm below the lash line (from the lower lid punctum to the lateral canthus). Use a scalpel to incise the skin, keeping the orbicularis oculi muscle intact. Reflect the eyelid skin from the orbicularis oculi muscle 4-6 mm inferiorly. Use fine scissors to bluntly dissect the orbicularis oculi muscle free from the orbital septum at the lateral aspect of the incision. Carry a tunnel medially just deep to the orbicularis oculi muscle moving toward the medial canthus. Take care to avoid exposure of orbital fat as the scissors are used to join the tunnel with the external skin incision. The result is a stair-step incision that closes in layers, and reduces the risk of postoperative lower lid ectropion. The dissection is then completed as previously described (see transconjunctival dissection), and the orbital rim is exposed. This technique keeps the lower lid retractors intact and eliminates the need for a lateral canthotomy and cantholysis. Disadvantages include an external incision and an increased risk of postoperative lower eyelid ectropion when compared to the transconjunctival approach. Endoscopic approach The utility of the sublabial incision can be greatly enhanced with the use of a 4-mm, 30-degree surgical endoscope. The sublabial application of a surgical endoscope can play a role in both the diagnosis and treatment of ZMC as well as orbital blowout fractures. For orbital rim fractures, sublabial insertion of the endoscope medial and lateral to the infraorbital nerve allows the surgeon to assess the reduction of the inferior orbital rim. Special care must be taken to avoid excessive tension on the infraorbital nerve while attempting to obtain an adequate cavity for endoscopic exposure. The endoscope can then be used to assist with application of a 1.0-mm miniplate along the orbital rim. Because the screws will be oriented toward the orbit from below, the surgeon must take special care to avoid extension of the screws through the rim and into the orbit. After extensive soft tissue dissection and completion of the repair, soft tissue resuspension should be performed. A midface suspension stitch (4-0 or 5-0 monofilament absorbable suture) can be passed from the malar fat pad, superolateral to the temporalis muscle fascia or a titanium plate. Traction on the suture allows the surgeon to resuspend the malar fat pad at the desired height. In orbital blowout fractures, transmaxillary reduction of orbital blowout fractures is currently on the cutting edge of endoscopic facial fracture repair. The idea of transmaxillary repair of orbital blowout fractures is not new. Walter described it in 1972. Most surgeons did not embrace the technique for fear of injury to the orbital contents while performing a blind reduction. The endoscope now provides an excellent view of prolapsed orbital contents into the maxillary sinus and greatly improves the accuracy of a transmaxillary reduction. However, great caution must be used when applying this technique. The surgeon must have extensive experience in traditional orbital approaches and repair of orbital blowout fractures. After endoscopic identification of small trap door fractures (see Diagnostic procedures), torn mucosa from around the fracture site should be removed with a Cottle or Freer elevator. The prolapsed orbital contents can then be reduced into the orbital cone. Finally, the bone fragments can be snapped back into place without the need for an orbital implant. Small-to-intermediate fractures can be repaired in a similar fashion. Often, removal of small bone fragments is necessary. After reduction of the orbital contents, the orbital floor can be reconstituted by inserting an appropriately trimmed piece of porous polyethylene (0.85 mm thick) through the maxillary antrostomy, maxillary sinus, and into the orbital defect. Large defects must be repaired via traditional open approaches. However, endoscopic assistance can be an extremely helpful addition. After traditional exposure of the orbital floor defect, it can be very challenging to view the stable bone of the posterior orbit when looking tangentially along the orbital floor. However, precise placement of the implant into the posterior orbit and on top of the bony shelf (without impinging on the optic nerve) is vital to accurate orbital reconstruction. The author believes that sublabial, transmaxillary endoscopic visualization of the orbital floor makes identification of the posterior orbital shelf and implant placement much easier and more reliable, while reducing the risk of optic nerve injury. The endoscopic approach to the orbital rim and floor is an evolving technique that shows great promise in augmenting our current methods. As the techniques and instrumentation are refined, the need for external incisions will be significantly reduced. However, the surgeon must show caution with any endoscopic repair and be inclined toward a traditional approach if any question of adequate reduction or entrapment of orbital contents exists. Zygomatic arch buttressFour common approaches to the zygomatic arch are available. Direct percutaneous approach This technique is less commonly used but offers a rapid and minimally invasive method for repair of mildly displaced ZMC fractures. After general endotracheal anesthesia, insert a towel clip, heavy suture, or bone hook through the skin at the site of injury. Pass the instrument deep to the zygomatic arch and apply lateral traction to reduce the fracture. Caution must be used to avoid any slippage of the instrumentation because tissue laceration and injury to the facial nerve may result. If the fracture reduces easily and is stable to palpation, no further treatment is necessary. Stability and accuracy of reduction can be difficult to assess if soft tissue edema is present. Although an incision is avoided, this technique does not allow direct observation, bimanual surgical manipulation, or stabilization of the fracture. Temporal (Gillies) approach The author prefers this approach for isolated fractures that are mild to moderately displaced. This approach requires a 2-cm incision placed behind the temporal hairline approximately 6 cm above the zygoma. Carry the incision through the skin, temporoparietal fascia (superficial temporal fascia), and temporalis muscle fascia (deep temporal fascia). Use a Freer elevator to dissect a tunnel superficial to the temporalis muscle and deep to the zygomatic arch (Gillies, 1927). Limit dissection around the fracture site to minimize the risk of fracture destabilization. Once the dissection is beneath the zygomatic arch, insert a Boise elevator and apply lateral pressure to reduce the bone fragments. A Rowe-Killey elevator also can be used for resistant or partially healed fractures. Care must be taken to avoid using the parietal scalp as a fulcrum for these instruments. This can result in a parietal skull fracture. The need for rigid fixation is uncommon in isolated arch fractures. An empty Glasscock ear dressing or a molded aluminum finger cot (foam padded) can be taped over the zygomatic arch for 3-7 days after the repair. Advantages of this technique include no visible scar, protection of the facial nerve, and bimanual reduction of the fracture. Transoral approach The transoral approach uses a gingivobuccal sulcus incision (see Zygomaticomaxillary buttress). Expose the anterior insertion of the zygomatic arch, and place a Boies elevator deep to the zygomatic arch. Apply lateral pressure to reduce the fracture. Avoid using the dental arch as a fulcrum as palatal fractures can occur. Advantages of this technique include no visible scar, protection of the facial nerve, and bimanual reduction of the fracture. Hemicoronal The hemicoronal approach is generally reserved for severe injuries with marked comminution of the zygomaticomaxillary complex. Expose the temporalis muscle as described earlier (see Frontozygomatic buttress). Approximately 2 cm above the zygomatic arch, make a horizontal incision through the superficial layer of the temporalis muscle fascia, and expose the temporal fat pad. Use a periosteal elevator to dissect onto the zygomatic arch. Caution must be used to stay in a subperiosteal plane. If the dissection is too superficial and disrupts the temporoparietal fascia, the facial nerve can be injured. If the dissection is too deep, the temporal fat pad can be disrupted and result in postoperative temporal wasting. Exposing the lateral aspect of the zygomatic arch from the root of the zygoma to the frontozygomatic buttress completes the dissection. Preoperative detailsAppropriate antibiotic coverage should be initiated before surgery and continued for approximately 24 hours postoperatively. Many surgeons continue antibiotic therapy for 7-10 days; however, the literature does not support any clear benefit from this practice. Intraoperative detailsFracture reduction Fracture reduction is indicated in all patients who are likely to have a residual aesthetic deformity or functional deficit. A review of the literature reveals that 77-94% of patients with ZMC fractures require surgical reduction (Knight, 1961; Yanagesawa, 1973; Ellis, 1985). Many authors advocate closed reduction of ZMC fractures through more limited surgical approaches (Matsunaga, 1977; Ellis, 1985; Zingg, 1992). Accurate closed reduction can be achieved in many cases. However, many reports in the literature cite difficulty in obtaining adequate reduction, even with direct observation (Donald, 1976; Jackson, 1989; Zingg, 1991, 1992). Therefore, closed reductions are generally reserved for fractures with mild displacement and little soft tissue edema. Also, the patient must be willing to accept an increased risk of postoperative asymmetry. The key to successful open surgical repair is strict adherence to basic principles. These principles include adequate (but not excessive) exposure, precise reduction, and accurate stabilization when necessary. The surgeon must view the fractures and remove any granulation tissue that may inhibit bone apposition and healing. Use geometric irregularities on opposing fracture surfaces for precise anatomic alignment. Slight inaccuracies in reduction at one fracture site can be amplified at distant sites. Key buttresses that can be observed include the frontozygomatic, inferior orbital rim, zygomaticomaxillary, and the lateral orbital wall (zygomaticosphenoidal). The frontozygomatic, zygomaticomaxillary, and inferior orbital rim exposures provide information about displacement of the ZMC primarily in the x (horizontal) and y (vertical) planes. Unfortunately, ZMC fractures rarely cause displacement in only one plane. Rotation of the ZMC often occurs along the axis of the frontozygomatic buttress because of masseter muscle pull (Matsunaga, 1977; Eisele, 1987). Visualization of the lateral orbital wall (zygomaticosphenoidal buttress) in combination with the frontozygomatic and zygomaticomaxillary buttresses provides information in all 3 planes, including rotation of the ZMC and changes in orbital volume. An accurate 3-dimensional understanding of the ZMC is essential to precise reduction and avoidance of postoperative asymmetry. Rigid fixation Open reduction with internal fixation is the mainstay of ZMC fracture repair (Donald, 1976; Karlen, 1979; Chuong, 1986; Ballenger, 1991). However, controversy exists regarding the need for 1-, 2-, or 3-point fixation. Some authors have advocated closed reduction in most cases (Knight, 1961; Lund, 1971; Lundin, 1973; Larsen, 1978). Other authors contend that all ZMC fractures require some form of fixation (Dingman, 1976; Wavak, 1979). Davidson (1990) evaluated this complex issue. Six skulls (12 zygomas), devoid of soft tissue, were placed in a test frame with a fiberoptic orthogonal measuring device. Traumatic ZMC fractures were simulated with a sagittal saw. The fractures were then reduced and fixated using different combinations of plates and wires. The study revealed that 3-point fixation using miniplates conferred the greatest stability. However, 3-point wire fixation was only slightly less stable. Mixing wires with miniplates reduced the stability in proportion to the number of wires used. Minimal increases in stability were added using3-point miniplate fixation when compared to 2-point miniplate fixation, regardless of the application site. The authors concluded that stable fixation can be achieved with a miniplate on the frontozygomatic suture line and a single wire on a second buttress. Acceptable stability can be achieved with single-point miniplate fixation at the frontozygomatic suture line or the infraorbital rim (Davidson, 1990). These results do not take into account variables such as fracture comminution rotatory forces of the masseter muscle or the type of skin incision necessary to apply the fixation. In a clinical setting, the need for open reduction and internal fixation is based on the anatomy, severity, and stability of the fracture. A mildly displaced tetrapod fracture with good stability may be amenable to closed reduction and require no fixation. Most fractures that require open reduction can be fixated with 1 or 2 miniplates. Comminuted ZMC fractures with bone loss can often require 3-point fixation and may even need 4-buttress stabilization with bone grafting. Miniplates are helpful in stabilizing free-floating segments and fixating bone grafts harvested from the anterior wall of the maxillary sinus, calvaria, or iliac crest. Most surgeons use titanium plates for internal fixation; however, wire fixation is time tested, inexpensive, and requires no special instrumentation. Unfortunately, wire fixation often requires more surgical exposure to see and grasp the wire on the deep surface of the fracture. Wires are also extremely difficult to use with comminuted fractures. Although miniplate fixation is more expensive and requires special instrumentation, it has several advantages. The surgeon does not need to see the deep surface of the fracture. Once the fracture is reduced adequately, a plate can be applied from the lateral surface. Plates are also much more effective with bone grafts and comminuted fractures. Most importantly, plate fixation adds stabilization to the fracture site in 3 spatial planes. Wires primarily prevent distraction of the fracture (x plane). They do not inhibit hinging or rotation at the fracture site (y and z planes). Miniplates add stabilization in all 3 spatial planes (x, y, and z), inhibiting distraction, rotation, and hinging at the fracture site. Resorbable plates offer many of the same advantages as titanium plates; however, they are reabsorbed within 3-12 months. The primary indication for the use of resorbable plates is in the pediatric population where long-term facial growth is a concern. Unlike titanium plates, resorbable plates contour very easily in situ. After heating the plate with warm water, small inaccuracies in bending can be corrected without difficulty. Mesh panels can also be applied. They offer multiple sites for insertion of screws and can be beneficial for comminuted fractures. Many patients see the use of an absorbable material as a significant benefit; however, little evidence exists to support greater clinical efficacy. Disadvantages of the resorbable plates include larger size and the need for tapping. A 2-mm resorbable plate has a higher profile than a 2-mm titanium plate and the equivalent strength of a 1.6-mm titanium plate. The larger resorbable screws also require more bone stock for application. In areas such as the orbital rim and nasoorbitoethmoid complex, resorbable plates can be prohibitively large. All resorbable screws require tapping before the screw can be inserted. This adds surgical steps and time to the procedure. Postoperative detailsPatients are observed for approximately 24 hours, and perioperative antibiotics are administered for 1-7 days depending the degree of wound contamination. Parenteral steroid administration may be used to reduce postoperative facial edema. Pressure dressings are applied only after coronal incisions to avoid postoperative hematoma. Gross visual acuity is checked in the recovery area and daily for the next 48 hours or until discharge. Follow-upCutaneous sutures are removed 5-7 days after the operation. Scalp staples are removed 10-14 days after the operation. Patients are then observed in follow-up visits after 1 month and again after 3 months. COMPLICATIONSOphthalmologic The most serious complication associated with a ZMC injury is blindness. While this condition may occur at the time of injury, multiple cases of iatrogenic blindness have been reported in the literature (Lederman, 1981); therefore, a preoperative ophthalmologic examination is essential. The surgeon should also assess pupillary size and symmetry prior to fracture repair. Intraoperative changes in pupillary size must be addressed. Local anesthesia containing epinephrine can result in transient pupillary dilation, which will resolve. Dilation of the pupil while traction is being applied to the globe (provided the other eye is closed) is a sign of optic nerve injury. Periodic intraoperative evaluation of pupil size and symmetry is recommended. Postoperative visual acuity checks are essential. Mild postoperative visual acuity changes can occur transiently in up to 30% of patients (Crumley, 1977). Significant postoperative loss of visual acuity is an indication for orbital reexploration, particularly if orbital implants were placed. Persistent diplopia is probably the most common ophthalmologic complication of ZMC fractures, occurring in approximately 7% of patients (Karlen, 1979; Dingman, 1964). Diplopia is noted most frequently in upward and far lateral gaze. Underlying etiologies include extraocular muscle entrapment, neurapraxia, or muscle contusion. If an iatrogenic entrapment is suspected, an urgent CT scan should be obtained. If the diagnosis is confirmed, rapid reoperation and release of the entrapped extraocular muscle is imperative. Diplopia that is felt to be secondary to neurapraxia or extraocular muscle contusion should be monitored for at least 6 months before any ophthalmologic surgical intervention is contemplated (Jelks, 1987). Lower eyelid malposition The lower eyelid can be separated into an outer lamella (skin and orbicularis oculi muscle) and an inner lamella (tarsal plate and conjunctiva). Lower eyelid ectropion occurs from excessive scarring in the outer lamella. This condition is most commonly associated with the subciliary approach. The resultant effect can range from simple scleral show to corneal exposure and ulceration. Appling (1993) cited a 28% incidence of permanent scleral show with the subciliary approach and a 3% incidence with the transconjunctival approach. Frank ectropion is observed in 0-44% of patients undergoing the subciliary approach and in 0-1.2% of patients undergoing the transconjunctival approach (Wray, 1977; Zingg, 1991; Appling, 1993). Lower eyelid entropion results from injury to the inner lamella and occurs most commonly with the transconjunctival approach. Eyelid entropion can result in corneal exposure and abrasion of the cornea by the eyelashes. In many cases, lid malposition and scleral show can be treated effectively with simple massage. If the lid malposition is severe and does not respond to conservative management, surgical repair can be performed. Ectropion is often associated with excessive lower lid laxity prior to surgery. A lateral tarsal strip procedure can reposition and tighten the lower lid. If the ectropion is severe, this procedure can be combined with lysis of the anterior lamella contracture and skin grafting. Entropion can be effectively treated with a release of the contracture and placement of a palatal mucosal spreader graft in the posterior lamella. The spreader graft facilitates eversion of the lower lid and prevents repeat contracture (Patel, 1997). Facial asymmetry Postoperative facial asymmetry occurs in 20-40% of patients (Perino, 1984). While facial fracture reductions can be strenuous and time consuming, failure to obtain adequate exposure and precise reduction at the time of initial repair often results in cosmetic deformities. Most postoperative irregularities require no surgical intervention; however, major asymmetry occurs in 3-4% of patients. Osteotomies and bone grafting may be required (Perino, 1984; Zingg, 1991). Paresthesias ZMC fractures often traverse the infraorbital foramen and result in infraorbital nerve injury. Preoperative evaluation and documentation of infraorbital nerve function is strongly recommended. Patients should be counseled that the sublabial incision itself will result in some transient postoperative anesthesia of the upper gingiva. The incidence of persistent sensory dysfunction ranges from 22-65% for open reductions and 9-40% for closed reductions (Zingg, 1991, 1992). In one large series, iatrogenic injuries were noted in 11% of open reductions (Zingg, 1991). Excessive traction or surgical manipulation of the infraorbital nerve during exposure and fracture reduction will also increase the risk of postoperative paresthesias. While these symptoms can be distressing to the patient, observation and reassurance are the most appropriate treatments. Attempts at surgical decompression or ablation are highly unpredictable (Donald, 1976). Coronal incisions will also result in postoperative paresthesias/anesthesia of the supraorbital and supratrochlear dermatomes distal to the incision. Aggressive manipulation of the nerve at the foramina can exacerbate these symptoms. Resolution of the paresthesias is slow and can be extremely frustrating to some patients. All patients should be warned regarding the postoperative sequelae and counseled that resolution of the symptoms (which may be partial or complete) cannot be expected for 3-12 months after the surgery. Miscellaneous
OUTCOME AND PROGNOSISUnacceptably poor surgical outcomes are uncommon. Significant facial asymmetry requiring surgical revision occurs in 3-4% of patients. Postoperative infection rates are extremely low, and these infections nearly always resolve with oral antibiotics. In general, the long-term prognosis after repair of ZMC fractures is very good. FUTURE AND CONTROVERSIESFuture advances in the treatment of facial trauma most likely will involve more extensive use of endoscopy for minimally invasive repair of traumatic injuries. Image-guidance surgery systems may also play a role in optimizing fracture reduction. REFERENCES
Maxillary Zygomatic Fractures excerpt Article Last Updated: May 1, 2007 |