Pertinent Anatomy, Fracture Configuration of Facial Factures and Craniofacial Approaches Sources • AO CMF Pertinent Anatomy • Frontal • OZ • NOE • Usually multiple facial areas of fractures FRONTAL Evolution over age The frontal sinus is generally absent at birth. At one year the anterior ethmoid air cells begin to invade the frontal bone. Frontal sinus growth is then complete at approximately 15 years of age. The frontal sinus has several critical anatomic relationships. These include: Sinus floor -> orbital roof/anterior ethmoid air cells Posterior table -> anterior cranial fossa Anterior table -> frontal contour The anterior table is thick (2-12 mm) and the posterior table is thin (0.1 – 4 mm). The frontal sinus drains via a small outflow tract into the ethmoid sinus/nasal cavity. The outflow tract is hour-glass shaped. True ostium is 3-4 mm at the narrowest portion. Each frontal sinus drainage pathway is located in the posterior, inferior, and medial portion of the sinus. • Important in endoscopic sinus surgery Orbitozygomatic ZYGOMA • 5 pillars of support • Quadripod/Tripod fracture -Lateral orbital wall -Lateral orbital rim -Infraorbital rim -Zygomatic arch -Zygomaticomaxillary buttress These pillars constitute five points of assessment for determining the degree of displacement of a zygomatic fracture • Buttress Concept ZYGOMA nasofrontal junction zygomaticofrontal Lateral buttress Medial buttress Lateral orbital rim infraorbital rim Lower transverse buttress Upper transverse buttress Squamous temporal zygomaticomaxillary zygomatic arch Attachment point of the masseter, temporalis, and zygomaticus major and minor muscles. • Infraorbital foramen: infraorbital nerve, artery and vein • 6-10mm below infraorbital rim The CT represents an axial slice, and shows a posterior displacement of the zygoma. This view also shows a fracture through the zygomatic arch. ORBIT 7 Bones Superior orbital fissure (SOF)syndrome: III, IV, V1, VI, Sup. And Inf. ophthalmic veins Orbital apex syndrome: blindness + SOF syndrome Orbital Floor Sagittal slices (hard-tissue window) and coronal soft-tissue windows of extraocular herniation into the sinuses. Orbital Roof • Most orbital roof fractures are blow-in fractures (displacement of the bone is towards the orbit). –from supraorbital ridge/maxilla trauma usually • Causes downward and forward displacement of the globe. Medial Orbital Wall Isolated left medial orbital fracture. Lateral Orbital Wall Isolated lateral orbital wall fractures are rare and only occur after isolated trauma to this anatomical structure. Much more common is a lateral orbital wall fracture together with a zygoma fracture (as shown). Internal Orbital Buttress, Posterior Ledge • Intact inferior orbital fissure and internal orbital buttress. CT scan and anatomic specimen showing an intact inferior orbital fissure (green arrow) without widening (the posterior ledge is marked with a blue arrow) and an intact internal orbital buttress (red arrow). • The inferior border of the medial orbital wall is the ethmoid-maxillary suture line. The bony condensation along this line is the internal orbital buttress. Enophthalmos: the ligamentous sling supporting the globe is disrupted. Shape of the inferior rectus: Rounding of the relatively flat inferior rectus is an indication of loss of ligamentous support and a higher likelihood of enophthalmos developing NOE NOE complex fractures involve the medial vertical (nasomaxillary) buttresses of the facial skeleton. Lacrimal Canaliculi • A full thickness laceration is defined as complete disruption of the anterior and posterior lamellar structures of the eyelid. • Laceration medial to upper/ lower punctae involves canalicular system with rare exception. • Most monocanalicular injuries can be treated with nil intubation of entire lacrimal system. • Bicanalicular lacerations will require utilizing a technique which places a stent through the entire system from the punctum to the nasolacrimal duct. Nasal Bones Anterior nasal spine fracture occurs in association to degloving injuries of the upper labial vestibule as in a steering wheel injury. Fracture Configurations of Facial Factures • Impact Force needed for fractures and Matchbox theory J Maxillofac Oral Surg. 2012 Jun; 11(2): 224–230. FRONTAL 1: Linear, minimally displaced fractures of the outer wall 2: Comminuted or depressed anterior table fractures (may or may not involve the nasofrontal duct) 3: Both anterior and posterior frontal sinus walls involved by comminuted fractures 4: Comminuted anterior and posterior wall fractures with dural injury and potential CSF leak 5: Comminuted anterior and posterior wall fractures with dural injury and potential cerebrospinal fluid leak in addition to tissue and/or bone loss. Manolidis, Seminars in Plastic Surgery 2002; 16(3): 261-272 • • • • • An anterior table fracture (A) A posterior table fracture (B) A nasofrontal recess fracture (C) A dural tear (CSF leak) (D) Fracture comminution Frontal Fractures Algorithm Observation Open reduction internal fixation (ORIF) Obliteration Cranialization Ablation ZYGOMA -displaced -comminuted Zygoma Common Fracture Patterns 1. 2. 3. 4. IOF (inferior orbital fissure) to FZ (Frontozygomatic) IOF to Maxilla orbital plate (infraorbital rim) IOF anteriorly to Maxilla infratemporal surface Zygomatic Arch ORBIT • Buckling theory- orbital floor-weakest part of orbital boundaries gives way • Hydraulic theory: globe content-> orbital floor • Blowout: herniation through floor • Trapdoor: herniation but return of # to original position NOE Markowitz/Sargent Classification (NOE) Markowitz BL, Manson PN, Sargent L, et al (1991) Management of the medial canthal tendon in nasoethmoid orbital fractures: the importance of the central fragment in classification and treatment. Plast Reconstr Surg. 87(5):843-53 TYPE I NOE Fractures (Markowitz) In unilateral Markowitz type I fractures, there is a single large NOE fragment bearing the medial canthal tendon. TYPE I NOE Fractures Involvement of the nasal bone The nasal bone may also be involved and, in cases of comminution, may not provide adequate dorsal support to the nasal bridge. TYPE II NOE Fractures In unilateral type II fractures, there is often comminution of the NOE area, but the canthal tendon remains attached to a fragment of bone, allowing the canthus to be stabilized with wires or a small plate on the fractured segment. TYPE III NOE Fractures In type III fractures, there is often comminution of the NOE area (as in type II fractures) and a detachment of the medial canthal tendon from the bone. Nasal Fractures Laterally displaced fractures -occur secondary to a lateral blow to the nose. Dorsal nasal septum displaced. Posteriorly depressed fractures -direct blow over the nasal bones, which are pushed inside to the ascending process of the maxilla. -The nasal septum is always involved. This type of fracture can be associated with NOE fractures. LEFORT The Le Fort classification is a historic classification still widely used to classify midfacial fractures. The Le Fort classification (René Le Fort, 1869-1951, France) is based upon experiments where cadavers were exposed to frontal impacts. Lefort I Le Fort I : -Horizontal maxillary fracture. may be linear (simple) or comminuted (complex). -Line extends from piriform aperture through the lateral maxillary and lateral nasal walls to the posterior region and will often include a segment of pterygoid plates. Lefort II Le Fort II: -pyramidal maxillary fracture. -fracture line: ptyerigoid region zygomaticomaxillary buttress medial infraorbital rim behind lacrimal bone and along medial wall of the orbit nasal dorsum crosses and proceeds to opposite side in same manner. -Various amounts of the pterygoid plates will usually remain attached to the posterior maxilla. Lefort III Le Fort III -craniofacial dysjunction: facial bones is separated from the cranial base. -fracture line: frontozygomatic suture lateral aspect of the internal orbit along the sphenozygomatic suture line inferior orbital fissure medially across floor of the orbit up the medial wall of the orbit dorsum of the nose where it crosses and proceeds to the opposite side in the same manner. AO Classification Level-1: presence of fractures in 4 separate anatomical units: the mandible (code 91), midface (92), skull base (93) and cranial vault (94) Level-2: detailed topographic location of the fractures Level-3: morphology—fragmentation, displacement, and bone defects Example: Code 92 Z0.I1.U1.I0 : Right to left classification Z0: Right side zygoma: single fracture line (nonfragmented fracture) I1. U1: multiple fracture lines (fragmented fracture) in the right ICM and UCM I0: non- fragmented fracture in the ICM on the left side. Craniofacial approaches Existing Lacerations Soft-tissue injuries can be used to directly access fracture sites for fracture management. Coronal Approach The coronal or bi-temporal approach is used to expose the anterior cranial vault, the forehead, and the upper and middle regions of the facial skeleton. The coronal approach is placed remotely in order to avoid visible facial scars. • The subperiosteal or subgaleal planes are commonly used for coronal flap dissection. • To protect the temporal branch of the facial nerve when the zygoma and the zygomatic arch are accessed, the superficial layer of the temporalis fascia is divided along an oblique line from the level of the tragus to the supraorbital ridge to enter the temporal fat pad. The dissection below this fascial splitting line is carried out just inside the fat pad deep to the superficial layer of temporalis fascia until the zygomatic arch and zygoma are subperiosteally exposed. For exposure of the nasofrontal and the nasoethmoid region as well as the medial orbit, the trochlea needs to be disinserted together with its connective tissue attachments from the frontal bone. Short sagittal incisions through the periosteum over the midline of the nasal dorsum will release the soft-tissue tension and facilitate the retraction of the coronal flap down to the osteocartilagineous junction. Intra-oral Vestibular approach The maxillary vestibular approach is simple and safe, as long as the dissection proceeds strictly in the subperiosteal plane. Though the overall morbidity is low, potential complications can occur from some of these anatomic structures: • • • • • Infraorbital nerve Nasolabial musculature Buccal fat pad Pterygoid venous plexus Zygomaticofacial nerve Endoscopic Evaluation A 1.0 to 1.2 cm skin incision is placed midway between the medial canthus and the glabella. The incision should be 1 cm inferior to the brow to avoid injury to the supratrochlear neurovascular pedicles. A small gull-wing-shaped incision can be used to avoid scar contracture. Circular Endonasal Incision Intercartilaginous incision (A) Transfixion incision (B) Nasal floor incision along the piriform aperture (C) • The upper lateral cartilages are left in place connected over the anterior septal border and linked to the cranial margin of the piriform aperture. • Degloving of the nose, nasal radix, and ethmoid region • After intranasal freeing, the soft-tissue envelope over the nose and the midface can be lifted in a subperiosteal and subperichondrial plane all the way up into the ethmoid region. Transoral (Keen)– lateral maxillary vestibular incision • Most direct access to the zygomatic arch. • Intraoral incision, and therefore does not have the risk of scar alopecia that will result from a temporal (Gillies) approach. • A 2 cm lateral maxillary vestibular incision (upper gingival buccal incision) is made with a scalpel or a cautery device just at the base of the zygomaticomaxillary buttress. The incision is made through mucosa only. Temporal (Gillies) approach - Skin incision The Gillies technique describes a temporal incision (2 cm in length), made 2.5 cm superior and anterior to the helix, within the hairline. A temporal incision is made. Care is taken to avoid the superficial temporal artery. Temporal (Gillies) approach - Exposure An instrument is inserted deep to the temporalis fascia and superficial to the temporalis muscle. Using a back-and-forth motion the instrument is advanced until it is medial to the depressed zygomatic arch A Rowe zygomatic elevator is inserted just deep to the depressed zygomatic arch and an outward force is applied. Great care should be taken not to fulcrum off the squamous portion of the temporal bone. Lower Eyelid Incisions There are three basic approaches through the external skin of the lower eyelid to give access to the inferior, lower medial, and lateral aspects of the orbital cavity: Subciliary (A, synonym: lower blepharoplasty) Subtarsal (B, synonym: lower or mideyelid) Infraorbital (C, synonym: inferior orbital rim) The subciliary approach can be extended laterally to gain access to the lateral orbital rim (D). • Infraorbital incisions lie at transition between the thin eyelid skin and the thicker cheek skin. • Predisposed to edema and increased visibility of the scars, even when the incision runs curvilinear within the resting skin tension lines. • lost its former popularity. Transconjunctival A) Transconjunctival (inferior fornix transconjunctival using a retroseptal or preseptal route) B) Transcaruncular (=medial transconjunctival) C) Transconjunctival with lateral skin extension (lateral canthotomy/”swinging eyelid”) D) Combination of inferior (A) and medial (B) transconjunctival E) C-shaped incision (ie, Combination of inferior (A) and medial transconjunctival (B) plus lateral skin extension (C)) • the retroseptal route enters directly into the fat compartments of the lower eyelids. • The preseptal route requires entering the suborbicularis oculi/preseptal space above the fusion of the lower lid retractors and the orbital septum. This allows direct visualization of the septum The soft-tissue space deep to the caruncle is spread in a posteromedial direction on top of Horner’s muscle. Following the surface of the muscle the dissection will proceed directly to the posterior lacrimal crest where the muscle inserts. The tip of the scissors may be used to palpate the underlying bone.
