Current Techniques for the Repair of Complex Orbital Fractures Miniplate Fixation and Cranial Bone Grafts Ralph E. Wesley, MD Background: Computerized imaging of complex fractures of the orbit and facial skeleton have brought about demands for methods of anatomic restoration. In this article, the author outlines techniques for metallic rigid anatomic fixation of facial fractures and the cranial bone graft method of augmentation. Methods: Clinical results of fracture repair using various types of metallic plates and replacement of missing bone with cranial bone grafts are presented and techniques are described. Conclusion: Rigid three-dimensional fixation of the facial skeleton with metallic plate fixation and augmentation with cranial bone grafts has produced more predictable correction of severe fractures of the orbit and facial skeleton. Ophthalmology 1992;99: 1766-1772
The ophthalmologist encounters an array offractures from the isolated blow-out to massive orbital disruption from high-impact, life-threatening injuries with major cosmetic and functional disruption. For the past decade and a half, computed tomography scans have shown in three dimen sions the anatomy of complex fractures and the effects on the orbital contents.
The ability to identify the pathologic anatomy of com plex orbital fractures has brought about the demand for techniques to correct the defects. The use of metal plate rigid fixation and cranial bone grafts has greatly simplified the techniques and improved the results in complex orbital fractures as described herein.
Clinical Evaluation Originally received: August 6, 1991. Revision accepted: June 12, 1992. From the Department of Ophthalmology, Vanderbilt University Medical Center and the Department of Ophthalmology, Centennial Medical Center, Nashville. Presented at the American Academy of Ophthalmology Annual Meeting, Atlanta, Oct/Nov 1990. Supported in part by a grant from Hospital Corporation of America Center for Research and Education, Nashville, Tennessee, and Research to Prevent Blindness, Inc, New York, New York. The author has no proprietary interest in developing or marketing any of the devices or materials mentioned in this article. Reprint requests to Ralph E. Wesley, MD, The Atrium, Suite 216, 250 25th Ave N, Nashville, TN 37203.
1766
Rarely are complex orbital fractures isolated injuries. 1 The force required to fracture certain bones indicates a greater chance of life-threatening systemic injuries. 2 Figure 1 shows that the nasal bone requires only 30g afforce from a fist for fracture to occur. A superior orbit rim fracture requires as much as 200g. Extensive orbital fractures, most often due to high-impact motor vehicle accidents, are more likely associated with intracranial injury, neck or spine fracture, chest injuries, damage to major abdominal organs, or long bone fractures. Nearly 52% of patients with facial fractures have associated closed-head injuries. 3 Computed tomography scans with axial, coronal, and occasionally sagittal views of complex orbital fractures
Wesley · Repair of Complex Orbital Fractures wire in and out of fragments can be extremely time con suming, especially for inexperienced operators. The wires may require removal when palpable or painful. Miniplates provide a rapid method to fixate fractures anatomically in three dimensions, thus eliminating judg ments of bone position based on swollen soft tissue. The miniplates of various shapes and configurations (Fig 3) usually are made of vitallium or titanium, which can be permanently implanted without interfering with com puted tomography or magnetic resonance imaging.
Surgical Technique
Figure 1. The diagram shows the amount of G force usually required to fracture portions of the facial skeleton. Areas requiring larger force for fracture are more likely associated with systemic injury.
The fragments are exposed and held in anatomic reduc tion in all three dimensions. A template ofsofter malleable metal is then placed over the fracture and molded down to the desired contour. The template is then removed, and the harder titanium or vitallium miniplate is then twisted and bent to match the contour of the template so the fracture fragments are not drawn out of their anatom ical alignment as the screws are tightened. The miniplate is held onto the bone using fixation for ceps by the assistant while the surgeon applies a tissue drill guide that centers the hole and ensures that soft tissue will not be caught up in the drilling. The thickness of the cortex of the fractured bone determines the length of the screw-usually 4 to 6 mm length around the orbit. A millimeter guide is used to measure the depth during dril ling so the hole matches the screw to give the firmest fit. Drilling a hole too deep in the frontal bone over the cra nium can result in a cerebrospinal fluid leak. If no bleeding is encountered, the leak will be plugged by the insertion of the screw. The hole is drilled at low speed of approximately 1000 RPM with copious irrigation to keep heat from damaging the bone. High drill speeds can cause wobbling that en larges the hole and reduces the tight fit of the screw. The plate should be applied by drilling one hole and applying
provide the most easily interpreted images of bone and soft tissue. Magnetic resonance imaging scans do not pro vide good bone images. Computed tomography scans can show unsuspected intracranial injuries, demonstrate the loss of floor and medial wall frequently responsible for enophthalmos, and show the three-dimensional position of the zygoma, which is critical to the cosmetic appearance of the orbit and mid face. Images of cranial bones with appropriate computer software can be rotated to view fractures in three dimensions (Fig 2) from any selected view or angle.
Miniplate Fixation With traditional interosseous wiring, forces are primarily applied in one dimension, which may allow fragments to twist, pivot, or rotate. Smaller comminuted fractures are particularly difficult to wire together in proper alignment without further splintering the small fragments. Passing
Figure 2. Computerized three-dimensional imaging of complex facial fracture of both orbits. The image can be rotated in the X, Y, and Z axis by the computer to view the fracture from any angle.
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Figure 3. Miniplates provide rigid fixation of the bony skeleton once fractures have been brought into alignment. Various shapes and config urations of miniplates can be twisted or bent to match the desired three dimensional contour of the facial skeleton.
the screw rather than trying to drill all the holes at once and then inserting screws. Two holes of the miniplate are fixated on one side of the fracture before fixating the op posite side. The remaining holes on the miniplate are then drilled and fixated one at a time. A small amount of bone wax on the screwdriver may help hold the small screw in the instrument while twisting the small screw in place. Right angle screwdrivers facilitate placement of screws and plates back inside the orbit, par ticularly along the lateral orbital rim or just inside the inferior rim. The lower profile screws (Fig 4) reduce the chance of soft tissue disruption or that the patient will feel the miniplate.
Clinical Cases Figure 5 shows a motor vehicle accident victim with min imal external injuries and fractures faintly seen on the plain x-ray (Fig 6A). The computed tomography scans (Fig 6B) graphically demonstrate displaced skull fract~res. With a coronal flap approach, dural tears were repaued with temporalis fascia grafting. The multiple comminuted fragments above the orbital rim wer~ fix~ted with a ~ew miniplates (Fig 7) with a great reductiOn m the operatmg time and better stability of the fragments. Interosseous wiring would have required wire to be passed through both the inner and outer tables of the skull to bring bone fragments together. The normal convex arch of the cra nium could not be maintained with interosseous wire. A displaced and rotated zygoma fracture can produce a major facial deformity (Fig 8) from downward displace ment of the lateral canthus, flattening of the malar em inence, widening of the face and enophthalmos. Plain x rays and clinical examination often cannot properly eval uate the zygoma with facial swelling masking the depressed nature of the malar eminence. Zygomatic complex frac tures are best evaluated on the computed tomography
1768
Figure 4. Comparison profile of two different screws. The lower-profile screw is less likely to be felt by the patient.
scan images comparing malar eminence projection and orbital rim level with the contralateral side aligning the greater wing of the sphenoid in the lateral orbit. 4 Figure 9A shows the images of a patient hit in the face with a baseball bat with minimal findings on plain x-rays. The computed tomography scans showed a dramatic widening of the zygomatic arch with the inferior orbital rim rotated downward and inward. The anterior face is flattened because of downward rotation of the malar em inence, but the width of the face is increased as the zy gomatic arch rotates outward. Exteriorly at the lateral orbital rim, this patient's fron tozygomatic suture had no displacement because of a twisting deformity at the suture. The posterior portion of the lateral orbital wall had a marked outward rotation not detectable from palpation or direct inspection ofthe lateral orbital rim (Fig 9B). The arch was rotated outward and the buttress of the zygomatic arch and the maxilla were severely displaced.
Figure 5. Patient with depressed skull fracture had minimal soft-tissue injury.
Wesley · Repair of Complex Orbital Fractures
Figure 6. A, plain x-rays show skull fractures only in two-dimensional complex. B, a computed tomography scan shows a severely depressed skull fracture with intracranial air, indicating possible intracranial contamination through a paranasal sinus.
Traditional interosseous wiring of the inferior orbital rim and the frontozygomatic suture leaves a widened ap pearance to the face. This fracture is best treated with "four-point" miniplate fixation (maxillary buttress, zygo matic arch, lateral orbital rim, and inferior orbital rim). The points that have the greatest value in helping with the alignment are the zygomatic arch, the maxillary but tress, and lateral wall of the orbit internally. When these are aligned, the fragment at the frontal zygomatic suture and the inferior rim also should be in place. The maxillary bone can be exposed using the fornix approach. 5 The but tress of the zygoma can be exposed by an upper buccal mucosal incision, and the zygomatic arch and frontozy gomatic suture can be exposed by direct incision or through a coronal flap that is carried down along the deep temporalis fascia to avoid injury to the frontal nerve. 6 With severely rotated zygomatic fractures, separation of the temporalis muscle from the lateral orbital rim and
The new smaller microplate systems allow accurate re duction ofsmall comminuted fragments around the fron tal sinus, the nasal area, and the inferior orbital rim. 7•8 Reduction would be difficult with interosseous wiring. The microplates require operating loops to manipulate the small plates and screws. The holding power of the micro plates is comparable with the larger miniplates, but larger plates are necessary to resist twisting and bending forces such as the masseter or temporalis muscle. The microplate should be applied first to the free fragment, and then the ends of the microplate are attached to the more stable
Figure 7. Miniplate fixation of severely comminuted and depressed orbit rim skull fracture with the re-establishment of normal bony convex con tour.
Figure 8. Left facial deformity from untreated zygomatic fracture with downward displaced lateral canthus, flattening of the malar eminence, widening of the face, and enophthalmos.
the masseter from the lateral portion of the malar emi nence will be required to elevate the fracture before mini plate permanent fixation.
Microplate Fixation
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Figure 9. A, a computed tomography scan shows outward rotation of zygomatic arch and inward rotation of anterior maxillary sinus from zygomatic fracture. B, no displacement at the front of the zygomatic suture but wide displacement of lateral orbital rim (arrow) internally demonstrated at orbital exploration.
bony segments. If the process is performed in reverse, the microplate is applied to stable fragments and then the surgeon must attempt to drill into free-floating fragments.
Micromesh Sheeting Enophthalmos after complex orbital fractures appears to come from expansion of the orbit rather than loss of fatty or other soft tissue. Smaller floor fractures can be bridged easily with a silastic or other alloplastic implant material. Larger defects that encompass the entire medial floor and the entire medial wall are difficult to bridge. 9 Several manufacturers now produce rigid fixation mesh implants for internal support ofthe soft tissue orbital con tents. We have used the micromesh 0.3-mm thick implant by Luhr (Luhr Maxillofacial Fixations System, Howmed ica Corporation, Rutherford, NJ). We fixate the implant to the inferior orbital rim and allow the micromesh to cover the floor and medial wall of the orbit (Fig 10).
Figure 10. Micromesh trimmed to appropriate orbital defect and fixated along the orbital rim with microscrews.
1770
An inferior fornix incision provides exposure of the floor and medial wall. The soft tissue should be completely cleared from the edges ofthe bony rim of the defect. Once the defect is covered by the micromesh, the implant can be fixed to the inferior orbital rim with the small micros crews. The use of a "contra-angle" or 90° drill head makes delicate microplate fixation at the rim or inside the orbit much easier (Fig 11). The Stryker system (Stryker Cor poration, Kalamazoo, MI) comes with low-speed and high speed heads, both of which are used with a linear foot pedal for maximum control. The high-speed head should be used to drill the holes but at a relatively low rotation easily obtained with the foot control. When inserting the microscrews, the low-speed head allows an extremely slow rotation to provide maximum control ofthe screw com parable to hand application. My experience, similar to that reported by Sargent and Fulks, 10 has been that ocular motility can be maintained
Figure 11. Contrahead 90° angle for use inside the orbit: fast-speed head available for drilling and slow-speed head for fixating twisting screws into implaht.
Wesley · Repair of Complex Orbital Fractures
Figure 12. A, air drill used to outline outer table cranial bone graft on cadaver skull. B, coal chisel in cadaver laboratory used to demonstrate cranial bone graft. Osteotomies in actual practice should be directed tangential to the skull and never at an angle that might penetrate the inner table.
without a barrier of bone or fascia between the orbital tissue and the implant. The major difficulty with this ma terial is getting it into the orbit. Manufacturers' adver tisements showing micromesh applied to defects on dry skulls do not provide an appreciation for the planning, exposure, and care required to slip these implants safely between the bony orbital wall and the retracted soft tissue. By using rigid wire micromesh, one can avoid the out ward bowing or sagging over large defects that occurs with alloplastic implants. Micromesh implants used during the past 2 years for large defects have provided far better cor rection of enophthalmos than alloplastic sheets.
Cranial Bone Grafts Previously, most bone grafts were taken from distant op erative sites like the rib or iliac crest from which pain, hematoma, pneumothorax, and scars can occur. Cranial bone grafts taken from the same operative site (Figs 12A and l2B) via a coronal incision allow selection of the proper convex configuration of the skull to match the curvature of external defects in the frontal bone above the superior orbital rim or to fill in the orbital internal lamina such as the floor. Membranous cranial bone grafts, when properly fixated, appear to experience less reab sorption than grafts from other sites. 11 Outer table cranial bone grafting usually is performed over the nondominant hemisphere in case an intracranial penetration or hemorrhage should occur. Grafts are not taken from the midline or across any sutures of the skull. The skin incision is carried down to expose the perios teum, which can be marked for the desired cranial bone graft. Using smaller grafts of l to 2 em in width reduces the chance of penetrating or fracturing the inner table. A drill is used to etch the outer table. Bleeding should occur when the drill has reached the depth of the diploe. A curved osteotome can be used with a gentle tapping technique tangential to the skull to remove the outer table.
This should be performed with great care. Healing will occur in most of the donor sites without significant defect. I like to perform this procedure either with a neuro surgeon or with neurosurgical standby available because complications can include intracranial penetration. Dural lacerations are rare and usually are not difficult to repair. The most serious complications involve violation of the vasculature, such as the middle meningeal artery. In ex perienced hands, cranial bone grafts usually involve less risk and less morbidity than iliac crest or rib grafts. 12 The split-calvarial bone grafts can be used alone to reconstitute the orbital floor or to provide "filler" for the posterior orbit. Fixation of the graft in a stable manner in close contact to the defect appears to accelerate early vascular ingrowth into the area for volume and structure of the bone graft. 13 The graft can be immobilized either with interosseous wiring or with miniplates. At my institution, micromesh implants are used more often than cranial bone grafts for correction of enoph thalmos. Bone grafts seem to be less predictable for long term correction of enophthalmos compared with rigid micro mesh sheeting. The reabsorption ofbone grafts may be more frequent in the posterior orbit and when exposed to an open paranasal sinus. The micromesh seems to be well tolerated after exposure to the sinus tissue. By using micromesh, one can avoid the possible intracranial com plications associated with harvesting cranial bone grafts. Micromesh also can be applied more rapidly. I prefer to use cranial bone grafts to correct defects of the orbital rims.
Conclusion The metal fixation plates and implants combined with cranial bone grafts have simplified methods to correct complex orbital fractures. The assistance of members of other medical specialties may be helpful in providing the best result for patients with complex orbital fractures. The
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metal plate fixation technique, although more expensive, provides more rapid reduction with greater stability of fractures than conventional interosseous wiring.
References 1. Derdyn C, Persing JA, Broaddus WC, et al. Craniofacial trauma: an assessment of risk related to timing of surgery. Plast Reconstr Surg 1990;86:238-47. 2. Luce EA, Tubb TD, Moore AM. Review of 1,000 major facial fractures and associated injuries. Plast Reconstr Surg 1979;63:26-30. 3. Davidoff G, Jakubowski M, Thomas D, Alpert M. The spectrum of closed-head injuries in facial trauma victims: incidence and impact. Ann Emerg Med 1988; 17:6-9. 4. Manson PN, Markowitz B, Mirvis S, et al. Toward CT based facial fracture treatment. Plast Reconstr Surg 1990;85: 202-14. 5. Patipa M, Slavin A. Axial dynamic compression plates in the management of complex orbital fractures via transcon junctival orbitotomy. Ophthal Plast Reconstr Surg 1990;6: 229-36.
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6. Gruss JS, Van Wyck L, Phillips JH, Antonyshyn 0. The importance of the zygomatic arch in complex midfacial fracture repair and correction of postraumatic orbitozygo matic deformities. Plast Reconstr Surg 1990;85:878-90. 7. Luhr HG. Indications for use of a microsystem for internal fixation in craniofacial surgery. J Craniofac Surg 1990; 1: 35-52. 8. Ellis DS, Toth BA, Stewart WB. A micro system for rigid bony fixation in orbital surgery. Ophthal Plast Reconstr Surg 1991;7:144-50. 9. Glassman RD, Manson PN, Vanderkolk CA, et al. Rigid fixation of internal orbital fractures. Plast Reconstr Surg 1990;86: 1103-111. 10. Sargent LA, Fulks KD. Reconstruction of internal orbital fractures with Vitallium mesh. Plast Reconstr Surg 1991 ;88: 31-8. 11. Zins JE, Whitaker LA. Membranous versus endochondral bone: implications for craniofacial reconstruction. Plast Reconstr Surg 1983;72:778-85. 12. Jackson IT, Heiden G, Marx R. Skull bone grafts in max illofacial and craniofacial surgery. J Oral Maxillofac Surg 1986;44:949-55. 13. Whitaker LA, Broennle AM, Kerr LP, Herlich A. Improve ments in craniofacial reconstruction: methods evolved in 235 consecutive patients. Plast Reconstr Surg 1980;65:561-70.
The ophthalmologist encounters an array offractures from the isolated blow-out to massive orbital disruption from high-impact, life-threatening injuries with major cosmetic and functional disruption. For the past decade and a half, computed tomography scans have shown in three dimen sions the anatomy of complex fractures and the effects on the orbital contents.
The ability to identify the pathologic anatomy of com plex orbital fractures has brought about the demand for techniques to correct the defects. The use of metal plate rigid fixation and cranial bone grafts has greatly simplified the techniques and improved the results in complex orbital fractures as described herein.
Clinical Evaluation Originally received: August 6, 1991. Revision accepted: June 12, 1992. From the Department of Ophthalmology, Vanderbilt University Medical Center and the Department of Ophthalmology, Centennial Medical Center, Nashville. Presented at the American Academy of Ophthalmology Annual Meeting, Atlanta, Oct/Nov 1990. Supported in part by a grant from Hospital Corporation of America Center for Research and Education, Nashville, Tennessee, and Research to Prevent Blindness, Inc, New York, New York. The author has no proprietary interest in developing or marketing any of the devices or materials mentioned in this article. Reprint requests to Ralph E. Wesley, MD, The Atrium, Suite 216, 250 25th Ave N, Nashville, TN 37203.
1766
Rarely are complex orbital fractures isolated injuries. 1 The force required to fracture certain bones indicates a greater chance of life-threatening systemic injuries. 2 Figure 1 shows that the nasal bone requires only 30g afforce from a fist for fracture to occur. A superior orbit rim fracture requires as much as 200g. Extensive orbital fractures, most often due to high-impact motor vehicle accidents, are more likely associated with intracranial injury, neck or spine fracture, chest injuries, damage to major abdominal organs, or long bone fractures. Nearly 52% of patients with facial fractures have associated closed-head injuries. 3 Computed tomography scans with axial, coronal, and occasionally sagittal views of complex orbital fractures
Wesley · Repair of Complex Orbital Fractures wire in and out of fragments can be extremely time con suming, especially for inexperienced operators. The wires may require removal when palpable or painful. Miniplates provide a rapid method to fixate fractures anatomically in three dimensions, thus eliminating judg ments of bone position based on swollen soft tissue. The miniplates of various shapes and configurations (Fig 3) usually are made of vitallium or titanium, which can be permanently implanted without interfering with com puted tomography or magnetic resonance imaging.
Surgical Technique
Figure 1. The diagram shows the amount of G force usually required to fracture portions of the facial skeleton. Areas requiring larger force for fracture are more likely associated with systemic injury.
The fragments are exposed and held in anatomic reduc tion in all three dimensions. A template ofsofter malleable metal is then placed over the fracture and molded down to the desired contour. The template is then removed, and the harder titanium or vitallium miniplate is then twisted and bent to match the contour of the template so the fracture fragments are not drawn out of their anatom ical alignment as the screws are tightened. The miniplate is held onto the bone using fixation for ceps by the assistant while the surgeon applies a tissue drill guide that centers the hole and ensures that soft tissue will not be caught up in the drilling. The thickness of the cortex of the fractured bone determines the length of the screw-usually 4 to 6 mm length around the orbit. A millimeter guide is used to measure the depth during dril ling so the hole matches the screw to give the firmest fit. Drilling a hole too deep in the frontal bone over the cra nium can result in a cerebrospinal fluid leak. If no bleeding is encountered, the leak will be plugged by the insertion of the screw. The hole is drilled at low speed of approximately 1000 RPM with copious irrigation to keep heat from damaging the bone. High drill speeds can cause wobbling that en larges the hole and reduces the tight fit of the screw. The plate should be applied by drilling one hole and applying
provide the most easily interpreted images of bone and soft tissue. Magnetic resonance imaging scans do not pro vide good bone images. Computed tomography scans can show unsuspected intracranial injuries, demonstrate the loss of floor and medial wall frequently responsible for enophthalmos, and show the three-dimensional position of the zygoma, which is critical to the cosmetic appearance of the orbit and mid face. Images of cranial bones with appropriate computer software can be rotated to view fractures in three dimensions (Fig 2) from any selected view or angle.
Miniplate Fixation With traditional interosseous wiring, forces are primarily applied in one dimension, which may allow fragments to twist, pivot, or rotate. Smaller comminuted fractures are particularly difficult to wire together in proper alignment without further splintering the small fragments. Passing
Figure 2. Computerized three-dimensional imaging of complex facial fracture of both orbits. The image can be rotated in the X, Y, and Z axis by the computer to view the fracture from any angle.
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Figure 3. Miniplates provide rigid fixation of the bony skeleton once fractures have been brought into alignment. Various shapes and config urations of miniplates can be twisted or bent to match the desired three dimensional contour of the facial skeleton.
the screw rather than trying to drill all the holes at once and then inserting screws. Two holes of the miniplate are fixated on one side of the fracture before fixating the op posite side. The remaining holes on the miniplate are then drilled and fixated one at a time. A small amount of bone wax on the screwdriver may help hold the small screw in the instrument while twisting the small screw in place. Right angle screwdrivers facilitate placement of screws and plates back inside the orbit, par ticularly along the lateral orbital rim or just inside the inferior rim. The lower profile screws (Fig 4) reduce the chance of soft tissue disruption or that the patient will feel the miniplate.
Clinical Cases Figure 5 shows a motor vehicle accident victim with min imal external injuries and fractures faintly seen on the plain x-ray (Fig 6A). The computed tomography scans (Fig 6B) graphically demonstrate displaced skull fract~res. With a coronal flap approach, dural tears were repaued with temporalis fascia grafting. The multiple comminuted fragments above the orbital rim wer~ fix~ted with a ~ew miniplates (Fig 7) with a great reductiOn m the operatmg time and better stability of the fragments. Interosseous wiring would have required wire to be passed through both the inner and outer tables of the skull to bring bone fragments together. The normal convex arch of the cra nium could not be maintained with interosseous wire. A displaced and rotated zygoma fracture can produce a major facial deformity (Fig 8) from downward displace ment of the lateral canthus, flattening of the malar em inence, widening of the face and enophthalmos. Plain x rays and clinical examination often cannot properly eval uate the zygoma with facial swelling masking the depressed nature of the malar eminence. Zygomatic complex frac tures are best evaluated on the computed tomography
1768
Figure 4. Comparison profile of two different screws. The lower-profile screw is less likely to be felt by the patient.
scan images comparing malar eminence projection and orbital rim level with the contralateral side aligning the greater wing of the sphenoid in the lateral orbit. 4 Figure 9A shows the images of a patient hit in the face with a baseball bat with minimal findings on plain x-rays. The computed tomography scans showed a dramatic widening of the zygomatic arch with the inferior orbital rim rotated downward and inward. The anterior face is flattened because of downward rotation of the malar em inence, but the width of the face is increased as the zy gomatic arch rotates outward. Exteriorly at the lateral orbital rim, this patient's fron tozygomatic suture had no displacement because of a twisting deformity at the suture. The posterior portion of the lateral orbital wall had a marked outward rotation not detectable from palpation or direct inspection ofthe lateral orbital rim (Fig 9B). The arch was rotated outward and the buttress of the zygomatic arch and the maxilla were severely displaced.
Figure 5. Patient with depressed skull fracture had minimal soft-tissue injury.
Wesley · Repair of Complex Orbital Fractures
Figure 6. A, plain x-rays show skull fractures only in two-dimensional complex. B, a computed tomography scan shows a severely depressed skull fracture with intracranial air, indicating possible intracranial contamination through a paranasal sinus.
Traditional interosseous wiring of the inferior orbital rim and the frontozygomatic suture leaves a widened ap pearance to the face. This fracture is best treated with "four-point" miniplate fixation (maxillary buttress, zygo matic arch, lateral orbital rim, and inferior orbital rim). The points that have the greatest value in helping with the alignment are the zygomatic arch, the maxillary but tress, and lateral wall of the orbit internally. When these are aligned, the fragment at the frontal zygomatic suture and the inferior rim also should be in place. The maxillary bone can be exposed using the fornix approach. 5 The but tress of the zygoma can be exposed by an upper buccal mucosal incision, and the zygomatic arch and frontozy gomatic suture can be exposed by direct incision or through a coronal flap that is carried down along the deep temporalis fascia to avoid injury to the frontal nerve. 6 With severely rotated zygomatic fractures, separation of the temporalis muscle from the lateral orbital rim and
The new smaller microplate systems allow accurate re duction ofsmall comminuted fragments around the fron tal sinus, the nasal area, and the inferior orbital rim. 7•8 Reduction would be difficult with interosseous wiring. The microplates require operating loops to manipulate the small plates and screws. The holding power of the micro plates is comparable with the larger miniplates, but larger plates are necessary to resist twisting and bending forces such as the masseter or temporalis muscle. The microplate should be applied first to the free fragment, and then the ends of the microplate are attached to the more stable
Figure 7. Miniplate fixation of severely comminuted and depressed orbit rim skull fracture with the re-establishment of normal bony convex con tour.
Figure 8. Left facial deformity from untreated zygomatic fracture with downward displaced lateral canthus, flattening of the malar eminence, widening of the face, and enophthalmos.
the masseter from the lateral portion of the malar emi nence will be required to elevate the fracture before mini plate permanent fixation.
Microplate Fixation
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Volume 99, Number 12, December 1992
Figure 9. A, a computed tomography scan shows outward rotation of zygomatic arch and inward rotation of anterior maxillary sinus from zygomatic fracture. B, no displacement at the front of the zygomatic suture but wide displacement of lateral orbital rim (arrow) internally demonstrated at orbital exploration.
bony segments. If the process is performed in reverse, the microplate is applied to stable fragments and then the surgeon must attempt to drill into free-floating fragments.
Micromesh Sheeting Enophthalmos after complex orbital fractures appears to come from expansion of the orbit rather than loss of fatty or other soft tissue. Smaller floor fractures can be bridged easily with a silastic or other alloplastic implant material. Larger defects that encompass the entire medial floor and the entire medial wall are difficult to bridge. 9 Several manufacturers now produce rigid fixation mesh implants for internal support ofthe soft tissue orbital con tents. We have used the micromesh 0.3-mm thick implant by Luhr (Luhr Maxillofacial Fixations System, Howmed ica Corporation, Rutherford, NJ). We fixate the implant to the inferior orbital rim and allow the micromesh to cover the floor and medial wall of the orbit (Fig 10).
Figure 10. Micromesh trimmed to appropriate orbital defect and fixated along the orbital rim with microscrews.
1770
An inferior fornix incision provides exposure of the floor and medial wall. The soft tissue should be completely cleared from the edges ofthe bony rim of the defect. Once the defect is covered by the micromesh, the implant can be fixed to the inferior orbital rim with the small micros crews. The use of a "contra-angle" or 90° drill head makes delicate microplate fixation at the rim or inside the orbit much easier (Fig 11). The Stryker system (Stryker Cor poration, Kalamazoo, MI) comes with low-speed and high speed heads, both of which are used with a linear foot pedal for maximum control. The high-speed head should be used to drill the holes but at a relatively low rotation easily obtained with the foot control. When inserting the microscrews, the low-speed head allows an extremely slow rotation to provide maximum control ofthe screw com parable to hand application. My experience, similar to that reported by Sargent and Fulks, 10 has been that ocular motility can be maintained
Figure 11. Contrahead 90° angle for use inside the orbit: fast-speed head available for drilling and slow-speed head for fixating twisting screws into implaht.
Wesley · Repair of Complex Orbital Fractures
Figure 12. A, air drill used to outline outer table cranial bone graft on cadaver skull. B, coal chisel in cadaver laboratory used to demonstrate cranial bone graft. Osteotomies in actual practice should be directed tangential to the skull and never at an angle that might penetrate the inner table.
without a barrier of bone or fascia between the orbital tissue and the implant. The major difficulty with this ma terial is getting it into the orbit. Manufacturers' adver tisements showing micromesh applied to defects on dry skulls do not provide an appreciation for the planning, exposure, and care required to slip these implants safely between the bony orbital wall and the retracted soft tissue. By using rigid wire micromesh, one can avoid the out ward bowing or sagging over large defects that occurs with alloplastic implants. Micromesh implants used during the past 2 years for large defects have provided far better cor rection of enophthalmos than alloplastic sheets.
Cranial Bone Grafts Previously, most bone grafts were taken from distant op erative sites like the rib or iliac crest from which pain, hematoma, pneumothorax, and scars can occur. Cranial bone grafts taken from the same operative site (Figs 12A and l2B) via a coronal incision allow selection of the proper convex configuration of the skull to match the curvature of external defects in the frontal bone above the superior orbital rim or to fill in the orbital internal lamina such as the floor. Membranous cranial bone grafts, when properly fixated, appear to experience less reab sorption than grafts from other sites. 11 Outer table cranial bone grafting usually is performed over the nondominant hemisphere in case an intracranial penetration or hemorrhage should occur. Grafts are not taken from the midline or across any sutures of the skull. The skin incision is carried down to expose the perios teum, which can be marked for the desired cranial bone graft. Using smaller grafts of l to 2 em in width reduces the chance of penetrating or fracturing the inner table. A drill is used to etch the outer table. Bleeding should occur when the drill has reached the depth of the diploe. A curved osteotome can be used with a gentle tapping technique tangential to the skull to remove the outer table.
This should be performed with great care. Healing will occur in most of the donor sites without significant defect. I like to perform this procedure either with a neuro surgeon or with neurosurgical standby available because complications can include intracranial penetration. Dural lacerations are rare and usually are not difficult to repair. The most serious complications involve violation of the vasculature, such as the middle meningeal artery. In ex perienced hands, cranial bone grafts usually involve less risk and less morbidity than iliac crest or rib grafts. 12 The split-calvarial bone grafts can be used alone to reconstitute the orbital floor or to provide "filler" for the posterior orbit. Fixation of the graft in a stable manner in close contact to the defect appears to accelerate early vascular ingrowth into the area for volume and structure of the bone graft. 13 The graft can be immobilized either with interosseous wiring or with miniplates. At my institution, micromesh implants are used more often than cranial bone grafts for correction of enoph thalmos. Bone grafts seem to be less predictable for long term correction of enophthalmos compared with rigid micro mesh sheeting. The reabsorption ofbone grafts may be more frequent in the posterior orbit and when exposed to an open paranasal sinus. The micromesh seems to be well tolerated after exposure to the sinus tissue. By using micromesh, one can avoid the possible intracranial com plications associated with harvesting cranial bone grafts. Micromesh also can be applied more rapidly. I prefer to use cranial bone grafts to correct defects of the orbital rims.
Conclusion The metal fixation plates and implants combined with cranial bone grafts have simplified methods to correct complex orbital fractures. The assistance of members of other medical specialties may be helpful in providing the best result for patients with complex orbital fractures. The
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metal plate fixation technique, although more expensive, provides more rapid reduction with greater stability of fractures than conventional interosseous wiring.
References 1. Derdyn C, Persing JA, Broaddus WC, et al. Craniofacial trauma: an assessment of risk related to timing of surgery. Plast Reconstr Surg 1990;86:238-47. 2. Luce EA, Tubb TD, Moore AM. Review of 1,000 major facial fractures and associated injuries. Plast Reconstr Surg 1979;63:26-30. 3. Davidoff G, Jakubowski M, Thomas D, Alpert M. The spectrum of closed-head injuries in facial trauma victims: incidence and impact. Ann Emerg Med 1988; 17:6-9. 4. Manson PN, Markowitz B, Mirvis S, et al. Toward CT based facial fracture treatment. Plast Reconstr Surg 1990;85: 202-14. 5. Patipa M, Slavin A. Axial dynamic compression plates in the management of complex orbital fractures via transcon junctival orbitotomy. Ophthal Plast Reconstr Surg 1990;6: 229-36.
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6. Gruss JS, Van Wyck L, Phillips JH, Antonyshyn 0. The importance of the zygomatic arch in complex midfacial fracture repair and correction of postraumatic orbitozygo matic deformities. Plast Reconstr Surg 1990;85:878-90. 7. Luhr HG. Indications for use of a microsystem for internal fixation in craniofacial surgery. J Craniofac Surg 1990; 1: 35-52. 8. Ellis DS, Toth BA, Stewart WB. A micro system for rigid bony fixation in orbital surgery. Ophthal Plast Reconstr Surg 1991;7:144-50. 9. Glassman RD, Manson PN, Vanderkolk CA, et al. Rigid fixation of internal orbital fractures. Plast Reconstr Surg 1990;86: 1103-111. 10. Sargent LA, Fulks KD. Reconstruction of internal orbital fractures with Vitallium mesh. Plast Reconstr Surg 1991 ;88: 31-8. 11. Zins JE, Whitaker LA. Membranous versus endochondral bone: implications for craniofacial reconstruction. Plast Reconstr Surg 1983;72:778-85. 12. Jackson IT, Heiden G, Marx R. Skull bone grafts in max illofacial and craniofacial surgery. J Oral Maxillofac Surg 1986;44:949-55. 13. Whitaker LA, Broennle AM, Kerr LP, Herlich A. Improve ments in craniofacial reconstruction: methods evolved in 235 consecutive patients. Plast Reconstr Surg 1980;65:561-70.
