In-Service Exam
Maxillo - Facial - 2001





Which of the following is the most common cause of posttraumatic enophthalmos?

(A) Fat atrophy
(B) Increased volume of the bony orbit
(C) Ligament disruption
(D) Orbital roof defect
(E) Soft-tissue contracture

The correct response is Option B.

Enophthalmos, or posterior displacement of the globe within the bony orbit, is most frequently caused by an increase in bony orbital volume. Because the positioning of the globe is determined by the bony orbit, ligamentous system, and orbital fat, changes in any of these contributing factors occurring as a result of trauma can lead to a change in globe position. However, volumetric studies have pointed to enlargement of orbital volume as the predominant cause of enophthalmos. As such, surgical correction of facial fractures should always include the confirmation and/or re-establishment of normal bony orbital volume. This involves confirmation of the correct positioning of the medial and lateral orbital floors.

Disruption of the orbital ligaments can also result in posttraumatic enophthalmos, especially in relation to increased bony orbital volume. In certain patients who have increased orbital volume, intact ligaments can function to maintain the globe in its normal position. However, if the ligaments are disrupted, the soft tissues can contract, resulting in a change in both orbital shape and volume. If this is not corrected, the globe will be positioned abnormally following healing, and the enophthalmos will then be difficult to correct.

Defects in the orbital roof are not commonly cited as a cause of enophthalmos because superior displacement of the globe into the anterior cranial fossa is rare.

References
1. Bite U, Jackson IT, Forbes GS, et al. Orbital volume measurements in enophthalmos using 3-D CT imaging. Plast Reconstr Surg. 1985;75:502.
2. Manson PN, Clifford CA, Su CT, et al. Mechanisms of global support and posttraumatic enophthalmos: I: the anatomy of the ligament sling and its relation to intramuscular cone orbital fat. Plast Reconstr Surg. 1986;77:193.
3. Manson PN, Grivas A, Rosenbaum A, et al. Studies on enophthalmos: II: the measurement of orbital injuries and their treatment by quantitative computed tomography. Plast Reconstr Surg. 1986;77:203.

In a patient undergoing surgical management of a Le Fort I fracture, rigid fixation is applied using metal plates and screws. When maxillomandibular fixation is removed to confirm the occlusal relationship, a unilateral posterior open bite is noted.

Which of the following is the most appropriate next step in management?

(A) Fixation with elastic banding on the side of the open bite for four weeks
(B) Re-establishment of maxillomandibular fixation for six weeks
(C) Removal of all rigid fixation and disimpaction of the maxillary fracture
(D) Removal of all rigid fixation followed by wire fixation of the fracture sites
(E) Replacement of the metal plates with absorbable (Lactasorb) plates on the side of the open bite

The correct response is Option C.

The most important management principal in this patient who has a Le Fort I fracture involves re-establishing the pretraumatic maxillomandibular orientation. Erich arch bars can be used to re-establish occlusion in patients with
If the maxilla has been impacted into the pterygoid plates, the occlusion will be angled superiorly toward the side of impaction. Therefore, if rigid fixation is applied before the fracture site is disimpacted, the patient will have an open bite on removal of maxillomandibular fixation. In order to prevent this, the impacted segments should be mobilized prior to the application of rigid maxillomandibular fixation, and an even plane should be established to correct the open bite.

Wires, elastic bands, and absorbable plates (Lactasorb) can be used to re-establish maxillomandibular fixation but will not correct the open bite.

References
1. Chidyllo SA, Jacobs JS. The application of dental splints in regard to the modern techniques of rigid fixation. J Craniofac Surg. 1994;5:136-141.
2. Rohrich RJ, Shewmake KB. Evolving concepts of craniomaxillofacial fracture management. Clin Plast Surg. 1992;19:1-10.
3. Yaremchuk MJ. Fractures of the maxilla. In: Cohen M, ed. Mastery of Plastic and Reconstructive Surgery. Boston, Mass: Little, Brown & Co; 1994;2:1156-1164.

A 27-year-old woman has numbness of the left cheek after being hit in the eye with a tennis ball. Radiographs show an orbital blowout fracture. Which of the following is the most likely cause of the numbness?

(A) Edema of the skin over the cheek
(B) Entrapment of the infraorbital nerve distal to the foramen
(C) Fracture of the body of the zygoma
(D) Fracture of the infraorbital rim
(E) Injury of the infraorbital nerve within the orbital floor

The correct response is Option E.

A patient who experiences paresthesias of the cheek skin after sustaining a pure blowout fracture of the orbital floor usually has an injury of the infraorbital nerve. This nerve, which is a branch of the maxillary division of the trigeminal nerve (V2), courses within the inferior orbital canal along the floor of the orbit and exits the body of the zygoma through the infraorbital foramen.

Patients with pure orbital blowout fractures rarely have involvement or fracture of the infraorbital rim or body of the zygoma. The fracture fragments from the orbital floor and medial orbital wall are typically displaced into the sinus. Edema usually occurs in the periorbital region and not the soft tissues of the cheek. Although there are no sites to entrap the nerve distally, patients with more extensive periorbital fractures can have an injury of the infraorbital nerve, but will exhibit additional physical findings.

References
1. Manson PN. Facial injuries. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:867-1141.
2. Nguyen PN, Sullivan P. Advances in the management of orbital fractures. Clin Plast Surg. 1992;19:87-98.

A 30-year-old man sustains an injury to the left side of the face in a fistfight. Radiographs show an isolated fracture of the zygomatic arch; surgical reduction of the fracture is planned. Following incision in the temporal region, the instrument should be passed immediately beneath which of the following layers of the scalp?

(A) Hair follicles
(B) Subcutaneous fat of the scalp
(C) Superficial temporal fascia
(D) Deep temporal fascia
(E) Temporalis muscle

The correct response is Option D.

In the temporal (Gillies) approach, a technique used for operative fixation of zygomatic fractures, the initial scalp incision extends down through skin, subcutaneous tissue, and the superficial and deep temporal fascia. An elevating device is then inserted to raise the fractured arch in order to facilitate effective reduction. This instrument is passed immediately beneath the deep layer of the deep temporal fascia, which lies just beneath the arch. Guiding the instrument beneath the deep layer of the deep temporal fascia allows for careful elevation of the fractured bone.

Because the hair follicles, subcutaneous fat, and superficial temporal fascia are all positioned superficial to the zygomatic arch, passing the elevating device beneath any of these structures will not allow for elevation of the zygoma and may instead result in damage to the frontal branch of the facial nerve. Guiding the elevating device beneath the temporalis muscle is a less optimal approach; if the surgeon passes the instrument too deeply, it will also pass beneath the coronoid process and make elevation of the zygomatic arch more difficult.

References
1. Feinstein FR, Krizek TJ. Fractures of the zygoma and zygomatic arch. In: Surgery of Facial Bone Fractures. New York, NY: Churchill Livingstone, Inc; 1987:136.
2. Rohrich RJ, Hollier LH, Watamull D. Optimizing the management of orbitozygomatic fractures. Clin Plast Surg. 1992;19:149-165.

In a 29-year-old woman who sustained trauma to the face during a rugby game four weeks ago, intranasal inspection with a nasal speculum shows a perforation of the nasal septum. A physical examination and radiographs obtained in the emergency department at the time of initial injury showed findings consistent with a displaced nasal fracture.

Which of the following is the most likely cause of the septal deformity?

(A) Foreign body perforation
(B) Nasal bone puncture
(C) Septal hemangioma
(D) Septal hematoma
(E) Turbinate bone perforation

The correct response is Option D.

The nasal septal perforation seen in this patient is most likely caused by a septal hematoma that was not diagnosed at the time of injury. Because undiagnosed septal hematomas can cause pressure necrosis of the nasal mucosa and cartilage and ultimately lead to septal perforation, intranasal inspection using a nasal speculum should be performed in any patient who has sustained a nasal fracture and/or trauma to the nasal bones. Any hematoma seen on intranasal inspection should then be immediately drained. A #11 blade or a #16-18 needle and syringe can be used for drainage of the hematoma in order to relieve pressure and allow blood to flow into the nose.

A foreign body, nasal bone puncture, septal hemangioma, or turbinate bone perforation is unlikely to result in a perforation of the nasal septum.

References
1. Manson PN. Facial injuries. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:867-1141.
2. Pollock RA. Nasal trauma: pathomechanics and surgical management of acute injuries. Clin Plast Surg. 1992;19:133-147.

A 24-year-old man has moderate ectropion three weeks after undergoing open reduction and internal fixation of a malar complex fracture through subciliary and intraoral incisions. Operative exploration of the orbital floor was performed to confirm fracture reduction.

Which of the following anatomic sites is the most likely origin of this patient's ectropion?

(A) Lateral canthal ligament
(B) Orbicularis oculi
(C) Orbital septum
(D) Skin
(E) Tarsus

The correct response is Option C.

This patient has ectropion that has most likely been caused by edema and scar contracture of the orbital septum. Incision into the first eyelid crease is recommended to prevent the development of this complication. This incision has the lowest associated incidence of ectropion because it preserves the innervation of the pretarsal portion of the orbicularis oculi; therefore, normal eyelid tone is maintained. Although there is no true skin shortage seen in this patient, longstanding ectropion can lead to further untoward complications.

The lateral canthal ligament and tarsus would not be affected by this incisional approach. Cutaneous deficiencies should not occur because skin should not be resected.

References
1. Bahr W, Bagambisa FB, Schlegel G, et al. Comparison of transcutaneous incisions used for exposure of the infraorbital rim and orbital floor: a retrospective study. Plast Reconstr Surg. 1992;90:585-591.
2. Jelks GW, Smith BC. Reconstruction of the eyelids and associated structures. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;3:1671-1784.
3. Wolfe SA, Davidson J. Avoidance of lower-lid contraction in surgical approaches to the inferior orbit. Operative Techniques Plast Reconstr Surg. 1998;5:201-212.

A 35-year-old woman sustains blunt trauma to the preauricular region during a field hockey game. Radiographs show a fracture of the condylar neck with medial displacement of the proximal fracture fragment. Which of the following muscles most likely contributes to the fracture displacement?

(A) Buccinator
(B) Lateral pterygoid
(C) Masseter
(D) Medial pterygoid
(E) Temporalis
The correct response is Option B.

In this patient who has a fracture of the condylar neck, displacement of the proximal fracture fragment is most likely caused by the action of the lateral pterygoid muscle. This muscle, which has two heads, is the only muscle that inserts directly on the mandibular condyle, on its anterior portion. The inferior head of the lateral pterygoid muscle arises from the lateral pterygoid plate and inserts into the anterior surface of the neck of the condyle; it acts to open the mandible. The superior head arises from the infratemporal crest, infratemporal surface of the greater wing of the sphenoid bone, and a portion of the squamous part of the temporal bone and inserts into the capsule and articular disk of the TMJ; it contributes to the motion of the articular disk. In patients with condylar fractures, the unopposed force of the lateral pterygoid muscle pulls the condylar head medially.

The buccinator muscle lines the oral cavity and has no attachments within the TMJ. The masseter muscle has its bony attachments at the zygomatic arch and along the inferior border of the lateral portion of the mandibular angle and body. The medial pterygoid muscle arises within the pterygoid fossa and inserts into the medial surface of the mandibular angle and ramus. The temporalis muscle originates at the insertion of the infratemporal fossa of the temporal bone and the coronoid process. This muscle does not attach to the TMJ.

References
1. Mendes D, Jacobs JS. Traumatic deformities and reconstruction of the temporomandibular joint. In: Cohen M, ed. Mastery of Plastic and Reconstructive Surgery. Boston, Mass: Little, Brown & Co; 1994;2:1220-1229.
2. Zide BM. The temporomandibular joint. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;2:1475-1513.

A 45-year-old man sustains an isolated fracture of the body of the zygoma that is displaced inferiorly and posteriorly. The accurate alignment of which of the following anatomic structures provides the most useful guide for surgical reduction of the fracture?

(A) Anterior maxillary wall
(B) Frontozygomatic suture
(C) Inferior orbital rim
(D) Lateral orbital wall
(E) Zygomatic arch

The correct response is Option D.

In this 51-year-old man who has a significantly displaced fracture of the body of the zygoma, accurate fracture reduction can be best accomplished using the lateral orbital rim as a guide. Although each of the structures listed above will provide useful information for accurate reduction of this type of fracture, the lateral orbital rim is least likely to be comminuted, and reduction of the lateral orbital wall with the greater wing of the sphenoid bone will allow for simultaneous correction of the reduction in all planes. Use of the lateral orbital rim for accurate fracture reduction will reduce the patient's risk for development of malar flattening, enophthalmos, and other secondary sequelae.

Reduction of the frontozygomatic suture will correct the inferior displacement but may leave persistent rotational changes. Likewise, although reduction of the anterior maxillary wall, the inferior orbital rim, or the zygomatic arch alone without reduction of adjacent structures will allow correction in one plane, the rotational defects may remain undetected.

References
1. Rohrich RJ, Hollier LH, Watamull D. Optimizing the management of orbitozygomatic fractures. Clin Plast Surg. 1992;19:149-165.
2. Smith ML, Williams JK, Gruss JS. Management of orbital fractures. Operative Techniques Plast Reconstr Surg. 1998;5:312-324.

Zygomatic osteotomies for increased anterior projection of the cheek bone will be most beneficial for which of the following patients?

(A) A 15-year-old boy who has Treacher Collins syndrome
(B) A 23-year-old woman who desires primary cheek augmentation
(C) A 32-year-old man who has facial flattening after sustaining panfacial fractures
(D) A 45-year-old woman who is undergoing rhytidectomy and bicoronal forehead lifting
(E) A 50-year-old man who has loss of malar projection one week after sustaining a zygomatico-orbital fracture

The correct response is Option C.

The 32-year-old man with panfacial fractures is the sole candidate of those listed above who should undergo zygomatic osteotomies, which are typically indicated to provide increased malar projection in patients who have scarring or inadequate vascularization of the soft tissues. Panfacial fractures are frequently caused by high velocity injury to the facial skeleton, often resulting in an equal distribution of force to all of the tissues of the face. Scarring and disturbance of soft-tissue vascularization are frequent. Although zygomatic osteotomies are never indicated in patients who have acute injuries, they can be considered if facial deformities persist following fracture repair.

In contrast, alloplastic augmentation is the procedure of choice in all other patients who require increased projection; this technique is easier to perform and is associated with fewer complications. The implants are easier to form and mold for the individual face.

In the 50-year-old man with inadequate malar projection following zygomatico-orbital fracture, open reduction and internal fixation are most appropriate.

References
1. El Deeb M, Wolford L, Bevis R. Complications of orthognathic surgery. Clin Plast Surg. 1989;16:825.
2. Rosen HM. When osteotomies should be considered. Clin Plast Surg. 1991;18:205-212.