ZYGOMATICOMAXILLARY COMPLEX FRACTURES (ZMC FRACTURES)

ZMC#

HISTORY

Fractured zygomas - Edwin Smith papyrus- 1650 BC

Duverney was the first surgeon- operative technique for treatment of fractured zygomatic arch -1751

He used intraoral finger pressure to elevate the depressed arch while the patient was asked to bite on a block of wood which resulted in tension of the temporalis muscle and tendon which along with the force from the finger in the outward direction resulted in reduction of the fracture.

Keens approach - early 20th century

ANATOMY

•  Also called tripod, trimalar fractures
  
• One of the three principal buttress of facial skeleton
• Critical to maintain normal facial width and prominence of cheek
• Process 🠆 articulates with
• Frontal 🠆 Frontal bone
• Temporal 🠆 Temporal bone
• Maxillary 🠆 Maxilla
• Orbital 🠆 Sphenoid (Greater wing)
  
• Muscles originating from the zygoma
• Masseter muscle from the temporal surface
• Zygomaticus minor, Zygomaticus major and Levator labii superioris from the malar surface
• Temporalis muscle and fascia at the posterolateral edge of temporal process
• Temporalis fascia attaches to the posterolateral edge of temporal process.
• Foramina
• Zygomaticofacial on malar surface (zygomaticofacial foramen)
• Zygomaticotemporal on the medial surface
• Nerves
• Second division of trigeminal nerve. The zygomatic, facial and temporal branches exit the foramina in the body of zygoma and supply cheek and anterior temporal region.
• Infraorbital nerve after passing through orbital floor exits from the infraorbital foramen. Supplies the anterior cheek, lateral nose , upper lip and maxillary anterior teeth.
  
• Other landmarks
• Whitnall's tubercle: medial surface of frontal process. One cm below the FZ suture. Both medial and lateral canthal tendons attach here.
  
• Lockwood's suspensory ligament maintains the horizontal axis of the globe. Attaches medially to the posterior lacrimal bone and laterally to the Whitnall's tubercle.
  
• Force required to fracture: 50-80g
• Bone itself is rarely fractured. Articulations are weak, mainly because of the architecture and size of the involved process.
• Part of the lateral buttress.
• Propagation of fracture lines:
• Zygomaticofrontal suture- medially to inferior orbital fissure
• From inferior orbital fissure anteriorly and laterally crosses the infraorbital rim, extending through infraorbital foramen, medial to the zygomaticomaxillary suture, inferiorly along the lateral antral wall inferior to the zygomatic buttress in a posterior direction.
• Inferiorly from inferior orbital fissure along the infratemporal aspect of maxilla-joins the anterior fracture below the buttress.
• Posterior to the zygomaticotemporal suture.
   

CLASSIFICATION

ZINGG CLASSIFICATION 1992

Type A: Incomplete zygomatic fracture. Low-energy injuries frequently cause isolated fractures of only one zygomatic pillar.

     A1: isolated zygomatic arch fracture

     A2: lateral orbital wall fracture

     A3: infraorbital rim fracture 

     Displacement of the malar complex does not occur because the remaining pillars are intact 

Type B: Complete monofragment zygomatic fracture (tetrapodfiacture). All four pillars of the malar bone are fractured and displacement may occur. 

Type C: Multifragment zygomatic fracture. Same as Type B, but with fragmentation, including the body of the zygoma.

KNIGHT AND NORTH 1960

Group 1: Undisplaced fracture - usually requires no treatment

Group 2: Displaced arch fractures - w/o involving walls of the antrum or the orbit. The classical three fracture line produces V shaped deformity

Group 3: Unrotated body fractures - displacement is backwards, inwards and slightly downwards. Usually because of direct blow to the zygomatic prominence. Waters view indicates infraorbital rim displaced inferiorly and medially at the buttress

Group 4: Medially rotated body fractures - displacement downward at the infraorbital margin. Blow from above the horizontal axis

         4A: Outward at malar buttress

         4B: Inward at FZ suture

Group 5: Laterally rotated body fractures - inward at malar buttress. Blow from below the horizontal axis.

         5A: Upward at infraorbital margin

         5B: Outward at FZ suture

Group 6: Complex fractures - with additional fracture line across main  fragment

ROWE AND KILLEY CLASSIFICATION 1968

Type 1: No significant displacement

Type 2: Isolated fractures of zygomatic arch

Type 3: Fractures rotated around a vertical axis

        3a: Internally 

        3b: Externally

Type 4: Fractures rotated around a horizontal axis

        4a: Medially 

        4b: Laterally

Type 5: Fracture displacement of the complex en-bloc

        5a: Medially

        5b: Inferiorly

        5c: Laterally

Type 6: Displacement of orbital floor

        6a: Inferiorly 

        6b: Superiorly

Type 7: Displacement of the orbital rim segments

Type 8: Complex comminuted fractures

ROWE AND WILLIAMS CLASSIFICATION

Fractures stable after elevation

    Arch only

    Fractures rotated along vertical axis (medial and lateral)

Fractures unstable after elevation

    Inferiorly displaced arch only

    Rotation around horizontal axis (medial and lateral)

Dislocations en-bloc

    Inferior

    Medial

    Lateral

Comminuted fractures

 YANAGISAWA'S MODIFICATION 1973

Group I: Undisplaced fracture

Group II: Arch only fracture

Group III: Medial or Lateral rotation around a vertical axis

Group IV: Medial or Lateral rotation around a longitudinal axis

Group V: Medial or lateral displacement without rotation

Group VI: Isolated rim fracture

Group VII: All complex fractures

LARSEN AND THOMPSON 1978

Group I: Nondisplaced fractures requiring no treatment. In case of doubt during initial evaluation about stability should be reevauluated after 1 week.

Group II: All fractures requiring treatment. Further divided into fractures stable and fractures unstable after reduction.

CLINICAL EXAMINATION

1. VISUAL STATUS

Fundoscopic and ocular examination

Mild and mostly transient injuries seen in 63% of patients include corneal abrasion, chemosis, mild impairment of accommodation and visual acuity, orbital emphysema

Moderate injuries seen in 16% include conjunctival abrasions, enophthalmos, traumatic pupillary changes, iridodialysis, lens damage, moderate to severe impairment of accommodation and visual acuity

Severe injuries seen in 12% include retrobulbar hemorrhage, gross proptosis, corneal laceration, hyphema, angle recession, severe reduction or loss of vision, visual field loss, choroidal tear involving macula, injury to optic nerve

In case of significant findings ophthalmologic consultation

2. EXAMINATION OF ZYGOMA

    1. Inspection

    - Symmetry

    - Pupillary levels.

    - Orbital edema

    - Subconjunctival hemorrhage

    - Anterior and lateral projection of zygomatic body

        Patient placed in recumbent position or reclining chair

        Surgeon from superior position evaluates the anterior and lateral position of zygomatic bodies comparing both the sides

    - Intraoral examination to check for ecchymosis in buccal sulcus and/or dentoalveolar fractures

    2. Palpation

    Infraorbital rim palpated with index finger followed by palpation of lateral rim with thumb and index finger (on the inner aspect on lateral orbital rim)

    Presence of tenderness suggestive of fracture

    Body of zygoma and zygomatic arch palpated with 2-3 fingers in circular motion and compared to the other side

    Intraoral zygomatic buttress is palpated with one finger

SIGNS &SYMPTOMS

1. Periorbital ecchymosis and edema
• Edema and bleeding into loose connective tissue of eyelids and periorbital area
• most common sign following fracture of orbital rim
• Can be differentiated from ‘black eye’ but ecchymosis is patchy in black eye but in ZMC fracture it forms a continuous sheet with zygomatic bone fracture 
2. Proptosis of globe
• Post septal edema or extravasation of blood- most commonly enters the space between the periorbita and the cone formed by extraocular muscles.
• If preseptal involves eyelids
• Greater degree of proptosis when fluid in present between the cone of extraocular muscles and the optic nerve sheath.
3. Flattening of malar prominence
• reported in 70-86% of cases
• seen more in case of distracted FZ suture and medial rotation or comminution
• if edema present then this sign can be elicited by depressing the index finger into soft tissue of zygomatic areas and then comparing it with contralateral side
4. Flattening over zygomatic arch
• loss of convex curvature in temporal area
• visual and digital comparison with opposite side
5. Pain
• present only if the fractured segment is mobile
• palpation of fracture elicits painful response
6. Ecchymosis of the maxillary buccal sulcus
• may occur with a small disruption of the anterior or lateral maxilla 
7. Deformity at the zygomatic buttress of maxilla intraorally
   
• palpation of anterior and lateral aspects and buttress - irregularities of normally smooth contour
• crepitation from comminuted fragments
• "absence makes fracture unlikely but presence doesn't establish one" - as pain can also be because of soft tissue injury
8. Deformity of the orbital margin
• if orbital rim involved. displaced - gap or step deformity
• tenderness may be present
9. Trismus
• seen specially when arch is medially displaced.
  
• incidence higher in cases of isolated arch - 45%
  
• impingement of translating coronoid process of mandible on the displaced fragments. the amount of displacement necessary is great
• may also be because of muscle spasm secondary to impingement by displaced fracture especially on the temporalis muscle
• deviation of mandible toward the fractured site on mouth opening nay be present
10. Abnormal nerve sensibility
• present in 18-56% of cases (Peterson)
• infraorbital nerve paresthesia more common in displaced fractures
• difficult to differentiate true anaesthesia from altered sensation of swollen edematous tissue
• seen when fracture passes through orbital floor, anterior maxilla causing shearing, tearing or compression
• disruption causes anesthesia of lower eyelid, upper lip and lateral part of nose
• if altered sensitivity of maxillary teeth and gingiva present - disruption of the infraorbital nerve in canal suspected (as ASA and MSA arise in canal)
• Usually neurapraxia or Neurotmesis which usually persists for eight to eighteen month but eventually completely disappears.
• Cranial nerves II to VI should be examined.
  
11. Epistaxis
• As the zygomatic bone displaces the wall of antrum in region of zygomatico-maxillary suture which fills the sinus with blood which often leads to unilateral epistaxis 
• disruption of sinus mucosa
• minor displacement
• Source of bleeding id disrupted Schneiderian membrane of the maxillary sinus.
12. Subconjunctival hemorrhage
• Month to six weeks
• Bright red as oxygen can pass through the conjunctiva and oxygenate the Hb in RBCs.
• Usually limited to the lateral half of conjunctiva.
13. Air emphysema
• Subcutaneous emphysema- through medial orbital wall via ethmoidal air cells mostly, rarely because of maxillary sinus.
• Air may also enter retroseptally.
• Classic crackling heard on palpation.
• Short lived, usually resolves in a few days.
• No blowing of nose should be instructed to the patient.
14. Displacement of the palpebral fissure
15. Unequal pupillary levels
• May be present without Diplopia 
• Depends on the level at which fracture has occurred
• If fracture below level of Whitnall’s tubercle where the suspensory ligament of Lockwood attaches, then zygomatic bone can be displaced downward without alteration in the globe of eye. If the fracture is above Whitnall’s tubercle then there will be downward displacement with the globe (Anti-mongoloid slant because of displacement of canthal ligaments). 
16. Diplopia
• Due to involvement of extra ocular muscles or nerves supplying these muscles 
• Often seen in early stages due to effusion and oedema of extra ocular muscles
• May also be present due to enophthalmos.
• Monocular may indicate detached retina or lens dislocation - OPHTHALMOLOGIC EMERGENCY
17. Enophthalmos
• Usually seen in severe cases when orbital floor is comminuted which leads to herniation of peri orbital fat into the sinus
18. Strabismus 
19. Globe injury
• Extrusion of fat through lid laceration - indication of globe injury
• Irregular pupil may be sign of perforated pupil
• Most vulnerable area- sclera in the region of attachments of recti muscle into the globe.

RADIOLOGICAL INVESTIGATION

Radiographs

1. Water's View/ Reverse Water's View
   
•  Single best radiograph for ZMC fractures.
• PA projection with head positioned at 27° to the vertical axis.
• visualization of sinuses, lateral orbit and infraorbital rim.
2. Caldwell View
• PA view with 15°
• To evaluate the rotation around horizontal axis
3. SMV
• directed from the submandibular region to the vertex
• helps in evaluation of zygomatic arch and malar prominence

Computed Tomography (CT Scans)

1.5 mm cuts preferred

To look for:

• Ruptured globe
• Dislocated lens
• Vitreous hemorrhage
• Retrobulbar hemorrhage
• Disruption of optic nerve
• Extraocular muscles
• Pre or post septal hematomas

TREATMENT

When not to operate?

    Lack of displacement, especially if radiographic diagnosis complements the physical diagnosis.

    Blindness in the uninvolved eye as it is unwise to risk the sight in the remaining functioning eye (even though the chances of loss of vision are less).

   

Why should fractures be reduced within 7-10 days? 

Waiting for 7-14 days gives time for the edema to dissipate. Soft tissues undergo fibrosis and contracture during this period which may retard healing. Beyond this time period the fracture may heal and may be difficult to reduce. Also, the edges of the bony fragments resorb which may make the fracture unstable.

When to go for closed reduction? (Three Criteria)

1. Non comminuted fractures as comminuted fractures are unstable.
2. Floor and medial wall can NOT need exploration
3. Can NOT be widely displaced at the frontozygomatic suture

Early surgical intervention is advised for muscle entrapment injuries by DeMann, Dortzbach and Elner

Approaches

Approaches to the inferior rim

Skin approach to expose infraorbital rim - less possibility of ectropion after edema subsides.

1. Infraorbital
2. Subtarsal
3. Subciliary
4. Transconjunctival

5. Lateral canthotomy

Approaches to the lateral rim

1. Eyebrow incision

2. Upper lid incision

Approaches to the zygomaticotemporal suture area

1. Pretragal incision

2. Coronal flap incision

Techniques for reduction

Majority fractures result in medial inferior or medial superior displacement- outward and superior/inferior vector.

Placement of instrument under body of zygoma and lateral elevation reduces most fractures.

Gillies Approach

Usually used for medially and/or inferiorly displaced zygomas.

Shaving of region of medial part of temporal fossa.

Bifurcation of superficial temporal artery identified. Usually, 2.5 cm above and anterior to the ear helix.

Incision made in this area through skin and subcutaneous tissue, at an angle from anterosuperior to posteroinferior, avoiding the artery. Sometimes the middle temporal vein maybe encountered.

Temporalis fascia exposed above bifurcation.

Lengthening of incision to allow insertion of Molt No 9 periosteal elevator between the fascia and temporalis muscle.

Sweeping of area medial to the zygomatic arch and the infratemporal portion of zygoma. 

Palpation of fracture.

Insertion of Rowe zygoma elevator in this created space. Blade should not be medial to coronoid process.

Handle is grasped and instrument is pulled laterally and superiorly while placing the other hand on the fractured zygoma to evaluate the reduction.

Usually, a click is heard once the zygoma locks into place.

Incision is closed.

Keen's Approach

Advantages:

No skin incision

Direct approach

Better reduction vector

No hazardous vessels during entry dissection

1.5cm incision in buccal sulcus inferior to the zygomatic buttress, adjacent to the attached mucosa, through mucosal and submucosal layers

Molt's no. 9 periosteal elevator used along lateral antral wall, subperiosteally → infratemporal surface of maxilla and zygoma exposed.

Dissection of medial surface of zygoma, locate the coronoid process.

Flat blade of Rowe's elevator placed under infratemporal surface of zygomatic bone.

The other hand placed over the operative site, elevator pulled superiorly and laterally. (head should be steadied)

Blade swept laterally, medial to zygomatic arch and lateral to coronoid process.

Lateral pull along the fractured portion.

Closure of incision.

Alternative instruments to Rowe's elevator: Kelly hemostat, Bone Hook

Carroll-Girard Screw

Most direct approach.

Corkscrew like device. T handle for grasping the instrument. Screw threads beginning on opposite end and ascending the length of the device.

A 5mm horizontal incision along the prominence of zygoma is needed to use this device.

Techniques for fixation

1. Wire osteosynthesis
2. Rigid fixation
3. External pin fixation
4. Maxillary antral support

REFERENCES

1. Bergeron JM, Raggio BS. Zygomatic Arch Fracture. [Updated 2020 Jun 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549898/ 
2. Markus Zingg, Kurt Laedrach, Joseph Chen, Khalid Chowdhury, Thierry Vuillemin, Franz Sutter, Joram Raveh, Classification and treatment of zygomatic fractures: A review of 1,025 cases, Journal of Oral and Maxillofacial Surgery, Volume 50, Issue 8, 1992, Pages 778-790, ISSN 0278-2391, https://doi.org/10.1016/0278-2391(92)90266-3.
3. Fracture of middle third of skeleton by Killey