Practical Plastic Surgery

37

Figure 37.1. Bony anatomy of the orbit.

canthal tendon which inserts on the anterior and posterior lacrimal crests may be torn or avulsed creating traumatic telecanthus. The medial rectus muscle can become entrapped or attenuated resulting in late medial gaze abnormalities.

The inferior orbital rim, composed of the maxillary and zygomatic bones, is the structure most often involved in orbital fractures. A direct force applied to the inferior orbital rim is transmitted to the orbital floor. Since the orbital floor is a relatively weak structure, it is prone to fracture, resulting in a blow-out fracture of the floor in which the orbital contents (mostly fat) herniated downwards. As the medial floor is thinnest portion, floor fractures typically occur medial to the infraorbital groove.

Diagnosis

Clinical

The diagnosis of orbital fractures is based on clinical and radiographic findings. Although many signs and symptoms have been described, the common signs include periorbital ecchymosis and edema, the presence of a palpebral or subconjunctival hemorrhage or hematoma (“the spectacle hematoma”), limitation of extraocular function (due to entrapment of orbital contents, edema, or neurologic sequelae), hypoesthesia in the distribution of the infraorbital nerve and enophthalmos.

Radiographic

Radiologic assessment of suspected orbital fractures should be performed with CT scanning as plain films are of little diagnostic benefit. Both axial and coronal views (1-3 mm) with reconstruction are preferable. Common CT findings of orbital floor fractures include an air-fluid level in the ipsilateral maxillary sinus, a trap door deformity of the orbital floor with herniation of intraorbital contents, and various other orbital rim or wall fractures (Fig. 37.2). There are two prevailing theories for the mechanism of orbital floor fractures. First, the hydraulic theory attributes the fracture to a sudden increase in intraorbital pressure. The elevation in pressure on the thinnest bone segment in the orbit, the floor, causes a blow-out fracture to

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Figure 37.2. Coronal CT scan showing a fracture of the orbital floor with fluid in the maxillary sinus.

ensue. The buckling theory attributes orbital floor fractures to the force transmitted to the infraorbital rim causing acute deformation with or without fracture. The force is passed on to the thin orbital floor which cannot adequately resist the force and fractures.

Associated Injuries

A wide range of associated ocular and periocular injuries have been reported in the literature (2-93%). Interestingly, the reported rate of associated injury is much lower for nonophthalmologist (2-25%) compared to ophthamologists (9-93%). A recent study of 365 patients with orbital fracture had an associated ocular injury rate of 26%. The injuries which required immediate opthalmologic intervention were as follows: traumatic optic neuropathy (35%), elevated intraocular pressure >40 mm Hg (26%), hyphema (22%), traumatic iritis (9%) and ruptured globe (9%). As a general rule, all patients with orbital fractures require evaluation by an ophthalmologist.

Indications for Treatment

Indications for treatment of a subacute orbital fracture (within 2 weeks of injury) include entrapment, enophthalmos, exophthalmos and bony defects greater than 1 cm2. The indications for immediate repair of acute orbital fractures are a nonresolving oculocardiac reflex, young patient (<18 yrs) with “white eye blow-out” associated with severe muscle entrapment, and a large fracture with globe prolapse into the maxillary sinus. Since orbital volume is roughly 20-30 ml, a 10% change in orbital volume (2-3 ml) may produce enophthalmos. As small volume changes can produce significant symptoms, a primary goal of treatment is anatomic reduction of the fracture to reestablish preinjury volume. If loss of osseous tissue interferes with anatomic realignment then autogenous or alloplastic grafts are necessary.

Graft Material for Reconstruction

Autogenous Grafts

Autogenous grafts described for orbital reconstruction include: bone (calvarium,

37ilium, rib, maxilla and mandible) or cartilage (nasal septal, costal and auricular). Calvarial grafts have been shown to be most beneficial in immediate reconstruction but tend to have problems with resorption when utilized in a delayed repair. Although described in the literature, cartilage grafts are infrequently used.

Alloplastic Grafts

Alloplastic implants can be divided into bioresorbable and nonbioresorbable types. Allogeneic bone and cartilage, lyophilized dura, gelatin film, polydiaxone plates, polylactide plates, and polglactin mesh and plates are all examples of bioresorbable alloplasts used in orbital reconstruction. The advantage of all alloplastic implants is their inherent lack of donor site morbidity. The disadvantages of lyophilized dura and allogeneic grafts are the lack of cellularity and potential for disease transmission. The primary disadvantage of resorbable plate systems is the concern over long term

stability especially in larger bony defects.

Nonbioresorbable implants include: silicone, methylmethacrylate, ceramics, polyurethane, polyethylene, porous polyethylene, titanium mesh and plates. All of these materials provide rigid support but have somewhat higher rates of infection than autologous tissues. Porous polyethylene has been shown to allow for fibrovascular ingrowth with pore sizes between 100-200 micrometers. Titanium mesh and porous polyethylene have been shown to mucosalize on the sinus-exposed surfaces of the implant.

Regardless of the method of reconstruction, patients with post-traumatic enophthalmos should be over corrected 2-3 mm to ensure adequate correction after resolution of edema. Over correction also helps to account for any volume loss secondary to fat necrosis. Opinions differ on the placement of orbital grafts. Some advocate rigid fixation, particularly of autogenous bone grafts, in an attempt to increase “take.” Others merely place grafts to span the defect and allow the soft tissue to redrape over the graft.

Techniques

Techniques in orbital repair are mainly dictated by the severity of the fracture and the types of incisions used for gaining access to the fracture site. For example, multiple surgical approaches may be necessary for a four-wall reconstruction, while a single incision may be used for an isolated single wall fracture. Access incisions to the orbital floor and infraorbital rim include subciliary, subtarsal and transconjunctival. A lateral extension of the incision and a lateral canthotomy can be used to gain access to the lateral rim.

Subcilliary Approach

The subcilliary approach described by Converse is made a few millimeters below the lash line. The incision is carried down through the orbicularis muscle to the tarsal plate. The plane above the tarsal plate can then be followed to the orbital septum and subsequently the orbital rim periostium which is then divided anteriorly for access to the orbital floor. In a stair-stepped approach, a plane is dissected anterior to the orbicularis until the inferior tarsal margin. The dissection then proceeds through the muscle to the orbital septum and the orbital periostium. In the

“skin only” subcilliary approach, the orbicularis muscle is divided at the level of the infraorbital rim, along with the orbital periostium. This variation of the subciliary approach is prone to skin flap necrosis, hematoma, ecchymosis and ectropion. Therefore, the skin/muscle flap techniques are preferred. The subcilliary incision extends

from the punctum medially to the lateral canthus laterally. A lateral release of ap- 37 proximately 1.5 cm can be added to increase exposure of the lateral orbital wall, frontozygomatic suture and malar eminence. Advantages of the subcilliary approach include a well-camouflaged scar and ease of dissection. An important disadvantage

is the higher incidence of scleral show than with a subtarsal approach.

Subtarsal Approach

The subtarsal approach, also popularized by Converse, is a version of a skin/ muscle flap technique. The incision is made in the skin of the subtarsal fold, or if obscured by edema, 5-7 mm below the lash line directed inferolaterally, approximating the crease. The orbicularis muscle is divided a few millimeters below the incision, and then the dissection continues to the orbital septum and orbital rim periostium. The subtarsal approach offers the easiest dissection technically and an acceptable scar although it is the most conspicuous of the techniques described here. Also, there tends to be more lid edema with this approach.

Transconjunctival Approach

The transconjunctival approach for access to the bony orbit was described by Tessier. The technique involves scleral-corneal protection followed by a conjunctival incision just below the lower tarsal margin. Dissection then proceeds inferiorly between the orbicularis oculi and orbital septum to the infraorbital rim. The infraorbital periostium is incised to gain access to the orbital floor. A lateral canthal or paracanthal release can be performed to allow for wider exposure of the lateral orbital wall. The advantage of this approach over the others is the absence of a visible scar and enhanced medial exposure. Disadvantages include limited lateral exposure without lateral release and a risk of postoperative ectropion.

Regardless of which technique is utilized, an important point to decrease lower lid retraction is to not divide the orbital septum or risk shortening it. Rather, one should incise the orbital periostium inferior and anterior to the rim.

Endoscopic Approach

Another technique available for repair of isolated orbital floor fractures is the endoscopic approach. Although this technique requires a specialized skill set with a learning curve, it does not violate the eyelid soft tissues and thus is inherently less morbid. An upper gingivobuccal incision exposes the anterior maxillary wall. The technique proceeds as follows:

•A 1-2 cm antral bone flap is created to access the maxillary sinus and orbital floor. The sinus is evacuated and packed with oxymetazoline pledgets to aid in hemostasis.

•The size and fracture configuration are defined using a 30˚, 4 mm endoscope. Complete removal of comminuted bony fragments is performed.

•Stable bony shelves are identified adjacent to the fracture. Either resorbable or nonresorbable bone grafts are cut slightly larger than the defect.

•The graft is introduced through the defect, rotated, and placed on the stable medial, lateral and anterior orbital shelves.

•Fixation is not required if there is adequate stability of the bony shelves. If not, direct screw fixation can be performed.

Complications

Many complications from orbital fracture repair have been reported. The most common include infection, visual disturbances, changes in visual acuity, diplopia, lid and canthal malposition (ectropion and entropion), lacrimal obstruction, re-

37sorption or malposition of implants, and infraorbital nerve dysesthesia. The most feared and dangerous acute postoperatve complication is retrobulbar hematoma with elevation of intraocular pressure. This is a surgical emergency which requires orbital decompression through immediate release of sutures and lateral canthotomy followed by control of hemorrhage. Steroids, diuretics and ice may also be of therapeutic benefit in this situation.

Pearls and Pitfalls

Orbital fractures with involvement of the medial orbital wall are significantly more likely to result in diplopia and exophthalmos than fractures without involvement of the medial wall.

Impacted fractures of the lateral orbital wall can be thought of as a “blow-in” fracture that may be accompanied by decreased visual acuity and ocular motility limitations. Early surgical treatment is warranted. Traumatic optic neuropathy will usually resolve with time.

Although extremely rare, retrobulbar hematoma following blunt orbital trauma is a serious complication since permanent loss of vision can ensue. It is due to postoperative or post injury orbital bleeding in the setting of an undisplaced orbital wall fracture. This results in increased intraocular pressure and ultimately ischemia of the optic nerve. The clinical presentation includes pain, exophthalmos with proptosis, internal ophthalmoplegia, and decreased or loss of the pupillary reflex. CT scan with thin-cuts is important in confirming the diagnosis. Any delay between the onset of symptoms and treatment can have a significant effect on functional recovery.

Suggested Reading

1.Cook Todd. Ocular and periocular injuries from orbital fractures. J Am Col Surg 2002; 195(6):831-834.

2.Manson Paul. The orbit after converse: Seeing what is not there. J Craniofac Surg 2004; 15(3):363-367.

3.Suga H, Sugawara Y, Uda H et al. The transconjunctival approach for orbital bony surgery: In which cases should it be used? J Craniofac Surg 2004; 15(3):454-457.

4.Rohrich, Rod, Janis J et al. Subciliary versus subtarsal approaches to orbitozygomatic fractures. Plast Reconstr Surg 2003; 111(5):1708-1714.

5.Manolides S, Weeks BH, Kirby M et al. Classification and surgical management of orbital fractures: Experience with 111 orbital reconstructions. J Craniofac Surg 2002; 13(6):726-737.

6.Jatla K, Enzenauer R. Orbital fractures: A review of current literature. Current Surgery 2004; 61(1):25-29.

7.Manson Paul. Facial fractures. In: Goldwyn R, Cohen M, eds. The Unfavorable Result in Plastic Surgery: Avoidance and Treatment. Philadelphia: Lippincott Williams and Wilkins, 2001:489-515.

8.Persons BL, Wong GB. Transantral endoscopic orbital floor repair using resobable plate. J Craniofac Surg 2002; 13(3):483-488.

required. Displaced fractures usually require several incisions for adequate exposure. A lower eyelid incision (subtarsal, subciliary or transconjunctival) exposes the infraorbital rim. A gingivobuccal sulcus incision exposes the zygomaticomaxillary buttress. The zygomaticofrontal suture can be exposed through the lower lid incision or through a lateral extension of an upper blepheroplasty incision. Coro-

38nal incisions should be used only when the arch must be visualized, such as in the case of a severely comminuted fractures. Once the fracture fragments have been adequately reduced, plate fixation is performed. The zygomaticofrontal suture is plated with a 1 mm plate. The zygomaticomaxillary buttress is plated with a heavier plate: either a 1.5 or 2 mm plate. Although two-point fixation is often adequate, some surgeons will also plate the infraorbital region with a 1 mm plate as well. This plate should be placed on superior surface of the rim so that it will not create a palpable step off.

Isolated zygomatic arch fractures require surgery in two cases: if there is a contour deformity or if trismus is present. Reduction is best achieved through a temporal hairline incision, termed the Gillies’ temporal approach. The bone fragment is elevated using an elevator passed along the surface of the temporalis muscle, deep to the temporoparietal fascia. Severely comminuted and displaced fractures may require open reduction. Once proper reduction has been achieved, the fragment may require stabilization. This can be done with plates or K-wire fixation.

Complications

Diplopia

Temporary diplopia can last up to 6 months. It resolves in about half the cases. The incidence of permanent diplopia is 5%. It is usually only apparent on upward gaze. It is most often due to entrapment of the inferior rectus muscle or adjacent tissue; however it can also occur as a result of injury to a nerve.

Enophthalmos

Patients will often notice this complication themselves. The zygoma must be completely separated and repositioned with plate fixation, thus restoring normal orbital volume.

Descent of the Malar Soft Tissue

This complication can result in loss of the normal malar contour. It can be prevented by adequate periosteal suspension of the malar tissue to the orbital rim following fracture fixation.

Optic Neuropathy

It can range from mild changes in color perception to blindness and is due to traumatic injury or ischemia of the optic nerve. A short course of high dose steroids is given in acute cases; however many patients will not resolve their visual defects. All patients with post-traumatic optic neuropathy should undergo high resolution CT scanning, and an ophthalmologist should be consulted.

Bradycardia

It is often accompanied by nausea and syncope. These symptoms are part of the oculocardiac reflex which is mediated by the ophthalmic division of the trigeminal nerve’s connections to the vagus nerve.

Maxillary Fractures

Classification

Most midface fractures occur along lines of bony weakness and fall into one of three patterns described by Le Fort (Fig. 38.1):

The Le Fort II fracture is the most common, followed by Le Fort I and III patterns. It is unusual to diagnose a fracture that falls purely into one of these three classifications. Most midface fractures are more complex and have components of other fracture types. The nasal bones do not tolerate impact well and may be fractured along with the maxilla.

Clinical Examination

Facial fractures secondary to high speed motor vehicle accidents have a risk of associated cervical fractures or neurological injury. A cervical spine examination should be performed and cervical spine films obtained in order to rule out a fracture. A full cranial nerve and mental status exam should also be performed. Another commonly associated finding is ocular injury.

Figure 38.1. Le Forte fracture classification. The lower figure shows a sagittal view of the fracture patterns through the midface bones (see Fig. 39.2)

Maxillary fractures should be suspected whenever there is malocclusion following trauma to the face. An awake patient can usually tell whether or not his teeth alignment feels normal. In addition to the occlusion, mobility of the midface should be determined by grasping the premaxilla and eliciting movement while holding the head still with the other hand. Le Fort I fractures will demonstrate only movement of the lower maxilla, whereas both Le Fort II and III fractures will demonstrate additional move-

38 ment at the nasal root. The Le Fort III fracture will also show lateral orbital rim motion. The orbital rims and nasoethmoid regions should be palpated to help determine the level of the fracture. Le Fort I fractures can be subtle in their presentation and do not usually demonstrate periorbital findings. In contrast, Le Fort II fractures can present with periorbital and subconjunctival ecchymosis. The face will also appear lengthened, and there will usually be massive swelling of the middle third of the face.

Radiographic Examination

The standard of care in diagnosing facial fractures is a CT scan with thin cuts in both the axial and coronal planes. Plain films are not routinely needed for evaluating the midface. Three-dimensional reconstructions are useful for planning surgery but are not required in the diagnosis of these fractures.

Treatment

Several principles should be followed in treating midface fractures. Whenever possible, the repair should be performed in a single stage along with concomitant soft tissue injury management. All of the fracture fragments should be exposed and precise anatomic reduction with internal plate fixation should be attempted. If necessary, autogenous bone grafting should be performed during the initial repair. Restoring normal occlusion is essential and relies on maxillomandibular fixation (MMF). The mandible should be reduced and stabilized as an initial step in order to provide an occlusive platform for the maxilla. Since the midface lacks adequate sagittal buttresses, the mandible and frontal bone should be used as buttress the maxilla.

Exposure

Low maxillary fractures should be approached through an upper gingivobuccal sulcus incision. The infraorbital rims can be exposed via a transconjunctival, subtarsal or subciliary (least preferred) approach. Occasionally, an extended lateral canthotomy is required. The nasoethmoid region is approached through a coronal incision.

Plate Fixation

A number of studies support the use of resorbable plates and screws in the treatment of maxillary fractures; however many centers still use nonresorbable hardware. Rigid internal, three-point fixation is the current standard for treating maxillary fractures. Compression is not required and should never come at the expense of preserving occlusion or normal contours. Gaps less than 5 mm can be tolerated, although defects secondary to comminuted buttress fractures should be filled with bone grafts. Postoperative movement of the fragments will impair normal healing. At least two screws should be placed on either side of the fracture line. Buttress fixation requires at least a 2 mm thick plate.

Fractures in Adentulous Cases

Adentulous individuals are usually elderly, and the goals of restoration of normal chewing and facial appearance may be less of an issue. The indications for open reduction with internal fixation are less rigorous. If the fracture is not displaced, a

Maxillary fractures in children are unusual. The mandible and nasal bones are much more frequently fractured. Minimally displaced and greenstick fractures can usually be treated conservatively. Displaced fractures should be treated with a similar approach as in adults: early repair with open reduction and internal rigid fixation. Plates and screws should not be placed near the tooth buds. Many surgeons will also remove any hardware once the fracture has healed. Traditional MMF in young children without permanent teeth is risky. If it is required, it can be accomplished with acrylic splints and circummandibular wires in order to avoid damaging the tooth buds.

Fractures of the Palate

Maxillary fractures can occasionally involve the palate and alveolus. As is the case with most maxillary fractures, wide exposure and rigid internal fixation is usually the recommended treatment. The Hendrickson classification describes the six most common fracture types: anterior and posterolateral alveolar (Type I), sagittal (Type II), parasagittal (Type III), paraalveolar (Type IV), comminuted (Type V) and transverse (Type VI). The first four types are treated using internal rigid fixation followed by several weeks of MMF. Comminuted and transverse fractures (especially those with multiple small segments) are often not amenable to adequate reduction and internal fixation and should be treated with a palatal splint. Simple alveolar fractures can often be treated with closed reduction and immobilization for 4-6 weeks. Exposure of the fracture can be achieved through a transverse or longitudinal vestibular maxillary incision. Longitudinal incisions are less likely to devascularize the mucosa; however care must be taken to avoid the greater palatine artery.

Complex Fractures of the Face

High speed motor vehicle accidents and gunshot wounds often produce complex facial fractures. After the initial trauma assessment and treatment of any concomitant life-threatening injuries, the craniofacial injuries can be addressed. A high resolution facial CT scan is required for identifying the various fractures. Three dimensional reconstructions are occasionally useful in preoperative planning. Most authorities agree that early definitive treatment should be attempted. A tracheostomy may be necessary, especially if prolonged ventilatory support is expected.

Any ophthalmologic emergencies should be addressed first. The next step is to obtain wide exposure of the fractures through the various incisions described above. The order in which the various segments of the maxillofacial skeleton are addressed depends largely on surgeon preference. The goals in treating complex facial fractures are: (1) to restore the facial buttresses; (3) to restore normal occlusion; (4) to stabilize the various fracture segments; (5) to achieve the normal facial contours whenever possible.

The mandible is addressed first. Any fractures are reduced and rigidly fixed, and the mandible is stabilized relative to the cranial base. Zygomatic fractures are then reduced and plated since these may interfere with proper reduction of the maxilla. Attention is then turned to the maxillary fractures. The buttresses are restored, and