Part 2. Operative Technique and Exemplary Repair

10.1055/b-0034-77712

■ Part 2. Operative Technique and Exemplary Repair

For several decades, operative repair of the orbit created controversy. Fortunately in recent years, the anatomy of the orbit and indications and approaches to orbital trauma repair have been elegantly delineated.4 , 8 , 9 , 23 41 The orbital trauma surgeon is particularly indebted to Tessier1 and Gerard Guiot and numerous other surgeons and anatomists, such as Whitnall2 and Zide.3 Their collective contributions produced operative paradigms that changed the way orbital repair after trauma has been effected.

About half of all orbital fractures involve the orbital frame, and the injury is then relatively extensive. In the other half, the injury is more isolated in the contoured, thin-boned midsection of the orbit. Management naturally differs in the two groups and their subsets. The bone of the orbital apex is seldom directly involved in populations of surviving patients. Rather, apical injury is most often noted in the nonsurviving cohort. Components of the orbital frame or orbital walls may collapse in isolation or in combination, creating unique functional disorders.

Satisfactory outcomes are a direct function of timely analysis and accurate clinical evaluation. Repeat examination of injuries of the periorbital region is commonplace, as initial intraorbital and periorbital swelling abates and HRCT is completed. A systematic approach on each examination increases the likelihood that subtle injuries will be recognized.42

Preoperative Assessment and Indications for Repair

Clinical Presentation

Initial ocular evaluation in the setting of periorbital fractures seeks to determine the status of pretraumatic vision and prior intraocular surgery, the functional and anatomic status of the eyelids and pupils, the quality of the anterior and posterior segments of the eyes, the state of ocular motility, and the current state of visual acuity. Armed with this information, the surgeon is able to declare (or not declare) the need for ophthalmologic evaluation.

Basic assessment is best achieved in six steps, avoiding meaningless generalities such as “examination grossly normal” or “ pupils equal, round, r eactive to light and a ccommodation,” as follows:

  1. Status of the eyelids (assessing the external and conjunctival surfaces)

  2. Size and shape of the pupils; reaction of the pupils to bright light, particularly the presence or absence of the afferent pupillary defect; and direct pupillary response to alternating light, as it passes briskly between the two eyes

  3. Clarity of the cornea and anterior chambers, attempting to ferret out asymmetries, corneal laceration, hemorrhage, globe rupture, and hyphema

  4. Ophthalmoscopic presence of a red reflex, macula, and optic nerve-head and absence of enfolding of the outer layer of the retina (commotio retinae)

  5. Complete range of motion in both vertical and horizontal gaze

  6. Distant and near vision, with one eye occluded (if vision is so challenged that fine print cannot be read, the ability to count fingers should be noted)43 46

Abnormalities in any of the six-point assessment merit ophthalmologic consultation.

Radiographic Assessment of Orbitozygomatic Fractures

The zygomatic fracture can be classified into three patterns of presentation ( Fig. 8.30A,B ):

  1. Medialward rotation, displacing the zygoma inward, downward, and posteriorly

  2. Lateralward rotation, displacing the zygoma downward, outward, and posteriorly

  3. Posterior displacement, with minimal rotation, similar to modest, inward displacement of a “swinging gate”

The pivot point of rotation is at the FZ suture, and the degree of rotation is largely dependent on the status (comminution) of the zygomatic arch and (the displacement of) the orbital plate of the zygoma. The relationship of the zygoma with the sphenoid (greater wing) and with the temporal bones (zygomatic process of the temporal bone) is key to gauging the degree of displacement; that same relationship is germane to anatomical repair of the fractured bone.

HRCT and three-dimensional reformats usually confirm the clinical examination, including step-offs at the inferior orbital rim and FZ suture. Although over projection of the malar prominence may occur, the cheek is usually under-projected and the face widened, because of splaying of the zygomatic arch (loss of linearity) and inward (posterior) displacement of the zygoma and its infrastructure.

Fig. 8.30 (A, B)

“Down-out-and-back” dislocation correlates with the tendency toward cheek ptosis, temporal hollowing, lowering of the lateral canthus, lateral scleral “show,” and expansion of the orbit. Orbital volume on three-dimensional computed tomography is expanded.

In cases with “down-in-and-back” rotation, the orbit is constricted. Orbital volume by three-dimensional measurement is reduced because of (or as a result of) inward displacement of the lateral orbital wall. The compressed orbital contents are placed at risk, requiring immediate ophthalmologic evaluation and rapid operative intervention ( Fig. 8.31 ).

Radiographic Assessment of Orbital Fractures

HRCT is required to reveal the nuances of soft-tissue injury and the extent of orbital fracture. Seldom can one depend on routine computed tomography to adequately reveal the extent of injury; 2.0-mm computed tomography and three-dimensional reformats are more revealing. The delay (to acquire additional radiographic study) and serial clinical examination favors resolution of intraorbital and periorbital edema before surgery.

Both astute radiologists and surgeons bear in mind that the risk of ocular injury is greatest when the principal fracture involves the orbit.47 51 Certain findings in the adult have an added risk of ocular trauma or optic nerve injury, in our experience:

  • The presence of orbital soft-tissue hemorrhage

  • Fractures associated with a decreased orbital bone volume

  • Fractures of the orbital apex or greater wing of the sphenoid, notably those extending to, or near, the optic strut and optic canal

Fig. 8.31

In the presence of these stigmata, clinical suspicion is particularly elevated.30 , 42 , 52 56

Orbital fractures in the adult are usefully grouped by region ( Tables 8.1, 8.2, and 8.3 ):

  • Fractures of the orbital frame

  • Fractures of the orbital midsection

  • Fractures of the orbital apex

Each major type and subset has distinguishing clinical and radiographic features,56 61 affecting greatly the decision to proceed (or not proceed) with observation or surgical intervention.36 38 , 62

Radiographic Assessment in Children

The high cranial-to-facial proportions, the presence of cartilaginous sutures, the resilience (almost “rubbery” consistency) of pediatric bone, and a lower cortical-to-cancellous bone ratio predispose children to unique injuries. This uniqueness is often apparent upon careful study of high-resolution radiographic (HRCT) studies.

Fractures of the pediatric midsection may be less apparent, even after 1.5- to 2.0-mm cuts, yet painful diplopia and abnormal forced ductions (suggesting muscle entrapment) are present on clinical examination. The clinical findings are quite incongruent with the relatively “innocent radiographs.” It has been hypothesized that this constellation occurs because preadolescent bone is better able to bend, crack, and snap back into position in contrast to the response of relatively brittle bone of adults, which tends to buckle under stress rather than staying hinged.38

In a second illustration of difference between the pediatric and adult populations, fractures in the orbital roof may obliquely traverse the superior orbital rim to join other faults in the anterior cranial vault.63 These fractures are typically minimally displaced.

Radiographs of late adolescence reveal more adult-like fractures of the orbital floor64 , 65 in contrast to those of younger peers, and fractures of the orbital roof follow the more typical pattern of injury of adulthood; that is, they are more medial and near the frontal sinus and nasoethmoid complex.

Operative Repair

Management of fractures of the three components of the orbital frame is key to reconstitution of periorbital and orbital anatomy. The sequence of prealignment and repair depends on clinical and radiographic findings. In general, we prefer to prealign the superior and medial orbital frame before proceeding to the inferolateral frame and the zygomatic arch, depending on intraoperative assessment (the instability of each trisection of the frame) and success of prealignment with wire. Reconstitution of the midsection of the orbit then follows and, in rare cases, also decompression of the contents of the orbital apex ( Fig. 8.32 ).

Table 8.1

Orbital Frame

Region or section

Associated fracture

Associated injury

Sequelae

 

Superior

Frontal bone or sinus

Cerebrospinal fluid leak (dura)

Meningitis; frontal sinusitis

 

Medial

Nasomaxillary, Orbitoethmoid

Cerebrospinal fluid leak (dural tear)

Ethmoiditis and nasal obstruction

 

Inferolateral

Zygomatico-orbital

Reduced orbital volume

Exophthalmos; higher risk of ocular injury

Table 8.2

Orbital Midsection

Isolated wall

Associated fracture

Associated injury

Sequelae

 

Roof

N/A

Pulsatile transmission intracranial pressure

Induced alteration of facial growth within weeks

 

Medial wall

N/A

Displacement of medial rectus into ethmoid sinus

Altered globe adduction without ischemia

 

Lateral wall

N/A

Expanded orbital volume

Enophthalmos

 

Floor

N/A

Entrapment medial rectus; trap-door deformity

Altered vertical gaze with ischemic myopathy

N/A, not applicable.

Incisions and Prealignment

Confirming the extent of injury and repairing most orbital fractures requires thorough exploration of the orbit and identification of numerous anatomical landmarks. Thus, exposure is key, taking into account that it is desirable to minimize postoperative scar and avoid eyelid malposition.

Three incisions provide exposure of fractures of the inferior and lateral orbital frame, orbitozygomatic complex, and orbit: coronal, transconjunctival/canthofornix, and gingivobuccal. The coronal incision across the bregma and the gingivobuccal incision in the maxillary vestibule are described in Chapters 3 and 4.

To orchestrate the canthofornix incision requires knowledge of 1) the concept of the anterior and posterior lamellae2 4 ; 2) the anatomy of the fornix4 , 66 68 ; and 3) the lateral attachments of the upper and lower eyelids to the lateral orbital frame.2 , 34 , 68 74

Critical to transconjunctival execution is attention to anatomic detail, the use of contoured protective lens, and the use of atraumatic technique. Pollock and Gossman, in a review of 200 patients in 2001, emphasize the benefit of extensive, prior fresh cadaveric dissection, three- or four-power loupe magnification, the use of blunt rakes and other modified retractors (to avoid untoward trauma to the eyelid, particularly the eyelid margin), and the need for finesse in reattaching the lateral canthus to the lateral orbital frame, in those cases in which the transconjunctival incision is extended across the lateral canthal tendon.73

The Concept of Lid Lamellae

Functionally, the lower eyelid has two lamellae.2 , 3 The anterior lamella contains skin, the orbicularis muscle and its investing fascia, and the orbital septum. The posterior lamella of the lower eyelid includes the conjunctiva, postseptal fascia, the capsulopalpebral fascia, and the inferior tarsal muscle (the lower eyelid retractor). When transconjunctival and canthal incisions are used, the anterior lamella is not violated (thus “bypassed”), except at the lateral canthus.73

Table 8.3

Orbital Apex

Region or section

Associated fracture

Associated injury

 

 

Superior

Sphenoid sinus

Optic neuropathy

Blindness

 

Medial

Ethmoid sinus

Carotid artery injury

Posterior ethmoid sinusitis

 

Inferolateral

Optic strut

Optic neuropathy

Blindness; superior orbital fissure syndrome

Fig. 8.32
The Concept of the Fornix

The palpebral and bulbar conjunctiva meet near the orbital floor in a sulcus, called the lower fornix.66 68 The lower eyelid retractors (the capsulopalpebral fascia and the inferior tarsal muscle) are beneath the conjunctiva of the fornix and ascend (conjoined with the orbital septum) to insert on the lower tarsus3 , 68 , 73 ( Fig. 8.33 ).

The Canthal Incision

Operating loupes are highly advised. The lateral canthus and fornix are infiltrated with local anesthetic containing epinephrine and hyaluronidase (1.0 mL hyaluronidase added to 9.0 mL of 0.5% or 1.0% lidocaine with epinephrine). A contoured protective lens (Danker Laboratories, Sarasota, FL) is inserted prior to initiating the incision. A suture is applied to the tarsus of the upper eyelid and placed at gravity with a small clamp to retract the upper eyelid out of the way ( Fig. 8.34 ).

The incision (with scalpel) begins at the lateral raphe and ascends and then descends in a subtle curve from the lateral canthus following the relaxed skin tension lines.68 , 73 76 The length of the lateral canthal incision varies but is some 0.5 cm in length in most cases, according to the extent of exposure planned. After achieving the skin incision with a scalpel, an insulated needle electrocautery is used to divide the orbicularis, minimizing bleeding. Attachments of the eyelid(s) to the lateral orbital rim are located and cut horizontally with sharp tenotomy scissors or with needle electrocautery close to the lateral orbital rim; in doing so, full eversion of the lower eyelid becomes possible.

Fig. 8.33
Fig. 8.34
Osseous Canthal Marker

Using the aforementioned technique for cantholysis, the upper arm of the posterior crus of the lateral canthal tendon (to the upper eyelid) is not transected and thus remains intact. In fractures limited to the orbital floor and lower medial wall, the posterior crus can later be used during closure to guide the reattachment of the lower eyelid.73

In recent experience (since our 2001 publication73 , 74), however, we have found it judicious to routinely place a partial-thickness 1.0-mm drill hole in the lateral orbital rim at the lateral canthal angle, marking the level of the lateral canthus. When surgery is redirected and a greater area of periosteal elevation is achieved than anticipated, the drill hole acts as a marker, rendering canthal repair straightforward. After the orbital floor and medial wall are repaired, for example, if it is decided to elevate periosteum superiorly along the later orbital wall and/or the frontal process of the zygoma, the drill hole guides the return of the canthal tendon to its prior anatomic location ( Fig. 8.35 ).

With the osseous marker in place, the entire lateral canthal tendon may be taken down and both eyelids released from their lateral attachment.

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Jul 2, 2020 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Part 2. Operative Technique and Exemplary Repair
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