What is Zygomatic Arch Fracture?
The zygomatic arch, or cheekbone, is part of the structure of your face. It’s formed by segments of the temporal bone (at the back) and the zygoma bone (at the front) and is essential for the appearance and shape of the middle part of your face. This arch is the primary reason for the width of your cheeks. It connects with several bones that make up your skull and face, and supports important muscles like the masseter (a jaw muscle) and zygomaticus major (a muscle used in smiling).
The zygoma bone and its connections with other facial bones make up the zygomaticomaxillary complex (ZMC), also known as the zygomatico-orbito-maxillary complex. If any part of the zygomatic arch or its connections with other bones breaks, it could lead to significant problems with function and appearance. Treatment for fractures in these areas should be specific to the patient and could range from simply monitoring the injury to surgically fixing the broken bone.
The zygomatic arch is the part of the midface that sticks out furthest from the side; this bone is responsible for protecting the base of the skull by absorbing and dispersing forces during injuries. The zygoma bone also plays an important role in the structure of the lower and outer walls of the eye socket. Whenever a fracture occurs in the zygoma bone, it’s necessary to also look for fractures in the eye socket.
The zygoma bone connects with four other bones forming the ZMC complex, including the temporal bone (forming the cheekbone), the maxillary bone (under the eye socket), the frontal bone (by the eyebrow), and the sphenoid bone (at the back of the eye socket). If you were to fracture your zygoma bone, setting these connections correctly is essential to restoring your facial proportions and the volume of your eye socket. These fractures are sometimes called “tripod fractures,” but the correct term should be “tetrapod fractures” because of these four bone connections.
Fractures to the ZMC can also lead to numbness in the face due to damage to sensory nerves. These nerves, such as the infraorbital nerve, the zygomaticofacial nerve, and the zygomaticotemporal nerve, are all connected to the zygoma bone and close enough to be affected by fractures.
Severe fractures in this region can also affect the movement of muscles like the temporalis which moves your jaw, and impede the normal function of the mandible, causing lockjaw. Mastication, or chewing actions, are often affected as well since the powerful masseter muscle, located at the lower aspect of the zygoma, could end up displacing unstable bone fragments.
The zygomaticus major and minor, muscles essential for facial expressions and smiling, also originate on the zygoma. Other important landmarks in this region include the special point of attachment for the ligament that supports the outer corner of the eye, located on the inner surface of the frontal process of the zygoma.
What Causes Zygomatic Arch Fracture?
Zygomatic arch fractures, or cheekbone breaks, often happen due to the result of severe trauma. Common causes are physical violence, car crashes, or injuries from sports. According to a 2020 study, assault was the leading cause of these types of fractures, making up 55% of cases, followed by falls at 27%, and car accidents at 18%.
However, a different study from 2012 found that assault and car accidents were equally common causes, each making up 29% of cases. In this study, sports injuries were next most common at 16%, followed by falls at 14%, accidents at home at 9%, and workplace accidents at 5%.
Risk Factors and Frequency for Zygomatic Arch Fracture
Fractures of the zygomatic arch, a prominent bone on your face, primarily occur in men, specifically those in their thirties to forties. Zygomaticomaxillary complex (ZMC) fractures, which involve the zygomatic arch and other facial bones, make up about 25% of all facial fractures.
- Most zygomatic arch fractures happen in males, around 80% of the time.
- These fractures commonly occur in the third to fourth decades of life.
- ZMC fractures account for about 25% of facial fractures.
- Racial/ethnic differences exist in the occurrence of these fractures. In descending order, the groups most frequently affected are:
- African Americans (61-64%),
- Caucasians (18-25%),
- Hispanics (7-12%),
- Asians (5-7%).
Signs and Symptoms of Zygomatic Arch Fracture
It’s essential to gather a thorough history when evaluating patients with zygoma fractures, including understanding how and when the injury occurred. Identifying the type of trauma that caused the injury, whether it was blunt force or penetrating, is critical because penetrating trauma is more inclined to damage deeper nerves and blood vessels. Additionally, it’s important to know if the patient has a history of prior facial trauma or surgeries, as this could complicate fracture repair.
When examining a patient with trauma, first and foremost, taking care of the patient’s “ABCs” is a must. This means ensuring the patient has a clear airway, is breathing on their own, and does not have uncontrolled bleeding. Any associated cervical spine injury should also be evaluated, as heavy impacts to the face or head can potentially affect the spine as well.
You should inspect the face, taking note of any visible abnormalities like asymmetry, cuts, and bruising. A bloody nose is common and may need to be treated if it’s severe. It’s necessary to conduct an eye examination, including checking the patient’s visual sharpness, field of vision, and eye movement.
In the case of a ZMC (zygomaticomaxillary complex) injury, the depression of the cheekbone might result in a flat look of the face that can be observed from a top view, aptly called a “bird’s eye” view. However, swelling of the overlying soft tissue in the early stages of injury might mask this flattened appearance. Cold compresses can help reduce swelling and allow for a more thorough examination.
Take note of the position of the eyeball; a condition called enophthalmos where the eye appears sunken might be observable from a “worm’s-eye” view. One should physically feel the face, checking for any misaligned bone fragments or movement of the skull and facial bones. Finally, a comprehensive check of the cranial nerves should be carried out, with specific attention given to facial movement and sensation.
Testing for Zygomatic Arch Fracture
If a doctor suspects a zygomatic arch or ZMC fracture, they will need to perform imaging tests after doing a thorough examination of your symptoms and medical history. Historically, a type of x-ray called the Waters view plain film was used for evaluating facial fractures. However, a different x-ray called a submentovertex view can offer a better view for investigating zygomatic arch fractures. Nowadays, the most effective imaging method is a computed tomography (CT) scan usually performed with fine cuts (less than 1 millimeter) and without contrast medium. Additionally, three-dimensional reconstruction imaging can be helpful for planning surgery. In some cases, doctors may suggest having a CT scan during surgery to assess the quality of the fracture correction, but the decision to do this on a routine basis is not yet supported by strong evidence.
There are different ways to categorize ZMC fractures. One classification system made by Zingg et al in 1992 includes these categories:
Type A: This is an incomplete zygomatic fracture that affects only one joint of the zygoma, the bone underneath the eye. This could involve a zygomatic arch fracture (A1), a lateral orbital wall fracture (A2), or an infraorbital rim fracture (A3).
Type B: Enter, when all four of the zygoma’s articulations, or joints, are fractured, but the zygomatic bone itself remains undamaged.
Type C: This is the most severe type, in which not only are all four articulations fractured, but the body of the zygoma is also broken.
Treatment Options for Zygomatic Arch Fracture
Zygomaticomaxillary complex (ZMC) fractures, also known as cheekbone fractures, can be managed in three main ways: medical treatment, closed reduction (manipulating the bone back into place without surgery), and open reduction internal fixation (ORIF – surgical treatment involving screws or plates). Each case of ZMC fractures is unique and requires a tailored approach.
For ZMC fractures with little or no displacement of the bone fragments, medical management, which involves observation and possibly a soft diet, may be adequate. Antibiotics are sometimes prescribed for 5-7 days, especially if the maxillary sinus is involved.
Operative management becomes necessary when ZMC fractures lead to aesthetic or functional problems, such as changes to the facial contour, difficulty opening the jaw (trismus), sunken eye (enophthalmos), double vision (diplopia), and numbness of the area supplied by the infraorbital nerve.
Surgical repair methods depend on factors such as the type and complexity of the fracture. For simple, low-impact fractures, closed reduction might be enough. Meanwhile, complex fractures or those that are likely destabilised after reduction typically require open reduction and internal fixation (ORIF). In ORIF, fractured bones are repositioned and secured with devices like plates, screws, or rods made from titanium or absorbable material.
Repairing fractures associated with ZMC, especially comminuted (shattered) ones, requires comprehensive planning, such as deciding on the number of fixation points and the order of plating. Repair should ideally take place within 2-3 days of the injury to minimize long-term complications, although repair beyond 6 weeks is also possible albeit more challenging. Deciding whether to repair the floor of the orbit (eye socket), which if disrupted can lead to abnormalities of eye movement or position, can be tricky and remains a topic of ongoing debate.
It’s crucial to note that each repair needs individualized approach. The strategies vary depending on the specific type and location of the fracture, and possible pre-existing factors. In some cases, soft tissue suspension, which involves reattaching avulsed (torn away) structures, might also be necessary. The aim of managing ZMC fractures is to restore the facial structure, symmetry and function while minimizing possible complications.
What else can Zygomatic Arch Fracture be?
The zygoma, or cheekbone, forms a big part of the lower and side walls of the eye socket. So if there’s a fracture in the cheekbone, doctors will check for possible damage to the eye socket, especially for serious injuries like an open eye wound. Also, doctors should rule out any injury to the neck spine.
Other facial fractures, including fractures to the forehead sinus, nose, middle face (like Lefort or naso-orbito-ethmoid), and jaw, should also be checked. An injury to the middle face can lead to a buildup of blood in the nasal partition, which needs immediate attention to prevent potential complications like holes in the nasal partition or a “saddle nose” deformity.
Lastly, problems with how the teeth close together, which may result from injuries to the jaw or middle facial area, should be assessed and taken care of as needed.
What to expect with Zygomatic Arch Fracture
Comminuted fractures, where a bone is broken into many pieces, of the ZMC (an area of the face) have a 33% higher rate of needing corrective surgery than simpler fractures. Another surgery might be necessary for certain patients, including 5% to 9% of those with non-comminuted (or straightforward) fractures, if the fracture doesn’t heal right.
Additional surgery is considered if certain symptoms persist, like a persistent sinking of the eye into the face, double vision, an irregular facial outline, or issues with the temporomandibular joint, which connects the jaw to the skull. Around 20% to 40% of patients experience a certain amount of unevenness in their facial appearance after their operation, with substantial unevenness occurring in 3% to 4% of cases. Numbness, also known as paresthesia, could be a long-term issue for 22% to 65% of patients.
Possible Complications When Diagnosed with Zygomatic Arch Fracture
Complications can happen after a ZMC fracture, which is a fracture of the cheekbone. These can be related to the initial injury, the surgery to correct it, or both. Here are some common complications:
- Pain
- Infection in the wound
- Asymmetry on the face
- Scarring
- Bleeding from the nose (epistaxis)
- Problems with the surgical hardware, such as it being exposed or easy to feel (palpability)
- Numbness or tingling sensation in the area below the eye (infraorbital nerve paresthesia)
- Sensitivity to temperature
- Weakening or total inability to move certain facial muscles (facial paresis or paralysis)
- Poor cosmetic outcome
- Degree of mouth opening is limited (trismus)
In some cases, there may be complications related to the orbit, or the eye socket, especially if there is also a fracture on the orbital floor. These include:
- Blindness
- Decreased sharpness of vision
- Problems with the position of the eyelid, such as ectropion (eyelid turning outward), entropion (eyelid turning inward), and lid malposition
- Exposure or scratch on the cornea, which is the front surface of the eye
- Drooping of the upper eyelid (ptosis)
- Watering eye (epiphora)
- Sunken eye or unequal positioning of the eyes (enophthalmos/orbital dystopia)
- Double vision (diplopia)
- Superior orbital fissure syndrome, a condition characterized by various symptoms like double vision, numbness, and vision loss
Recovery from Zygomatic Arch Fracture
The kind of aftercare and recovery time needed following surgery can differ greatly, depending on the severity of the injury and the kind of reconstructive methods used. No matter how major or minor the fracture, or which technique is used, it’s important that the patient avoids any heavy activity for a minimum of two weeks. This helps ensure full healing with little bruising or swelling. Depending on which specific fractures the patient has, aftercare may include the use of lubricating eye drops for orbital fractures, nasal rinses for fractures communicating with the sinus and nasal regions, oral rinses for internal mouth incisions, and a soft diet for jaw or mandible fractures.
For the areas where the skin has been cut, an antibiotic ointment is required. If the cut is near the eye, an eye-specific ointment is needed. This should be applied for at least three days after the operation. After this, a petrolatum ointment can be used until the cut has fully healed.
To improve the look of any remaining scars, patients should avoid sun exposure and use proper sun protection. Silicone-based scar creams and lotions can also be beneficial. After surgery, it’s crucial that the patient is closely monitored for any issues, particularly those related to infection or vision problems. Check-ups usually take place one week after the operation, and then every few weeks until the fractures are stable and any arising complications have been resolved.
Preventing Zygomatic Arch Fracture
Just like any other facial injuries, wearing helmets with face protection can help reduce the chances of getting Zygomatic arch (ZA) or Zygomaticomaxillary complex (ZMC) fractures. This is especially important when taking part in certain sports like ice hockey, American football, or when riding motorcycles, four-wheelers, or snowmobiles. Apart from these, wearing helmets correctly can also protect from other serious injuries, like skull fractures and brain injuries.
