Four wall box osteotomy of the orbits

The interorbital distance is measured with a caliper for reference. The osteotomies are planned so as to remove the maximal amount of interorbital bone so that when the orbits are translocated medially the interorbital distance is reduced to normal (25 – 30 mm in the adult) or preferably less than normal to allow for relapse. In the younger child this distance may be less, and is based on age and gender matched norms.

A coronal approach is performed but unlike in craniosynostosis, the temporal muscle is not completely taken out of the temporal fossa but only the anterior portion is retracted.

The orbit is degloved 360 degrees leaving the medial canthal tendon attached. This may be facilitated through the use of an additional palpebral incision ( subciliary or transconjunctival). An upper buccal sulcus incision is often used to expose the maxilla.

Note: Some surgeons detach the medial canthal tendon and reattach it at the end of the procedure.

The following pages provide general information regarding orbital anatomy and dissection

• Preoperative considerations
• Anatomy of the bony orbit
• Correlation of surface and cross sectional anatomy
• Introduction to periorbital dissection
• Orbital floor dissection
• Medial orbital wall dissection
• Lateral orbital wall dissection
• Orbital roof dissection
• Adjunctive access procedures (orbitotomies)
• Retrobulbar hemmorage

After the exposure of the forehead and the orbits, a bifrontal craniotomy beginning 1 cm superior to the superior orbital rim and extending to behind the coronal sutures is outlined.

Burr holes are first placed at the vertex, avoiding the sagittal sinus, and nasal frontal region as well as temporally. An epidural dissection between these points is made.

The neurosurgeon then completes the osteotomies using a craniotome.

After the bone flap is removed, the dura is freed from the anterior and middle fossae in the epidural plane.

The dura is protected with neurosurgical cottonoids.

Malleable retractors are used intracranially to retract and protect the dura and intraorbitally to protect the orbital contents while performing the osteotomies.

With retractors in the orbit and anterior fossa, an osteotomy beginning just behind the lateral orbital rim and through the lateral orbital wall is made with a saw.

A vertical osteotomy using a saw at the junction of the zygomatic arch and zygomatic body is completed.

The lateral orbital floor osteotomy is made with an osteotome placed just behind the lateral wall at the level of the zygoma and courses medially just anterior to the inferior orbital fissure to join the planned osteotomy of the medial orbit.

A right angle saw is turned intracranially and the orbital roof is osteotomized beginning at the lateral wall osteotomy and ending at the cribriform plate.

An osteotome is then inserted from intracranially and the medial orbital wall is osteotomized posterior to the canthus and to join the medial orbital floor osteotomy.

Using the upper buccal sulcus or lid incision, a saw is used to perform an osteotomy from the zygomatic eminence below the infraorbital nerve to the pyriform aperture.

Two parallel osteotomies are made from the anterior cranium down the side of each nasal bone to the bone cartilage junction.

An osteotome is then inserted intracranially just in front of or partially through the cribriform plate and an osteotomy is made through the cranial base and septum.

Preservation of some of the cribriform plate may help preserve some sense of smell. For severe hypertelorism this may not be possible.

The interorbital bone is then removed and stripped of mucosa. It may be used as a source for bone grafts.

The orbits should now be completely mobile and able to be translocated medially. Any interference with bone spicules or ethmoid sinus tissue may need to be removed with a rongeur. There may be bony interferences at the pyriform level requiring removal.

The orbits are moved medially and the lateral wall advanced anteriorly as well. Temporary fixation is secured with a medially placed wire or suture.

The gaps created temporally and along the zygomatic arch are now bone grafted and affixed with titanium plates and screws.

Plate fixation is also used medially between the two orbital segments.

If resorbable plates are available they may also be utilized as long as stability is assured.

Medial canthopexy (if necessary)
If the medial canthus has not been detached it will be moved with the bone segment. If it has been detached, a transnasal canthopexy will be necessary. This may be performed with wire and metallic plates as in posttraumatic reconstruction, with a bone anchor, or with stout transnasal sutures and bone grafts.

The frontal bone flap is then reshaped and replaced, held in place with titanium screws and plates. This may involve removing a medial segment of bone to allow a good fit with the reshaped orbits.

Most often additional nasal projection is required and an onlay cranial bone graft (cantilever bone graft) to the nose needs to be placed (inset). The amount of projection, shape and size of the bone graft depends upon the patient's deformity.

Some surgeons will remove midline redundant skin at this time, while others will do this as a subsequent surgical procedure because it may involve less risk of wound break down and nasal bone graft exposure than when performed at the time of the correction of hypertelorism.

Any residual defects in the cranium are now filled with bone shavings prior to closure of all wounds.

Clinical view.

Some surgeons use percutaneous bolsters to ensure adaptation of the skin to the underlying bone. However, these should be applied with great caution to avoid underlying skin necrosis.

Most surgeons favors placement of a bulb suction drain under the scalp for 3-5 days. Resorbable skin sutures are often used.

A circumferential head dressing is utilized for 48 hours. The neurosurgeon may request placement of a lumbar drain if significant dural tears have occurred during surgery. Patients should spend at least 1-2 days in an intensive care unit for neurological monitoring.

Keeping the patient’s head in an upright position postoperatively may significantly improve periorbital edema and pain. Some surgeons use injectable corticosteroids during surgery to reduce periorbital swelling.

To prevent orbital emphysema, nose-blowing should be avoided for at least 10 days.

The following perioperative medications are controversial. There is little evidence to make strong recommendations for postoperative care.

• Avoidance of aspirin or nonsteroidal antiinflammatory drugs (NSAIDs) for 7 days.
• Analgesia as necessary.
• Antibiotics (many surgeons use perioperative antibiotics. There is no clear advantage of any one antibiotic, and the recommended duration of treatment is debatable.).
• Nasal decongestant may be helpful for symptomatic improvement in some patients.
• Steroids may help with postoperative edema. Some surgeons have noted increased complications with perioperative steroids.
• Ophthalmic ointment should follow local and approved hospital protocol. This is not generally required in case of periorbital edema. Some surgeons prefer it. Some ointments have been found to cause significant conjunctival irritation.
• Regular perioral and oral wound care has to include disinfectant mouth rinse, lip care if intraoral incision has been used.

Postoperative examination by an ophthalmologist may be requested, although sever periorbital edema may prevent useful assessment. The following signs and symptoms are usually evaluated:

• Vision
• Extraocular motion
• Diplopia
• Globe position
• Lid position

Postoperative imaging has to be performed within the first days after surgery to verify accuracy of surgery. 3-D imaging (CT, cone beam) is recommended.

Remove sutures from skin after approximately 7-10 days if nonresorbable sutures have been used.
Apply ice packs for the first 12 postoperative hours as able although infants and young children do not tolerate this well (may be effective in a short term to minimize edema).
Avoid sun exposure and tanning to skin incisions for several months.

Soft diet can be taken as tolerated until there has been adequate healing of any maxillary vestibular incision. In children and infants age appropriate diets are then prescribed.
Patients in MMF will remain on a liquid diet until such time the MMF is released.

Clinical follow-up depends on the complexity of the surgery, and whether the patient has any postoperative problems. Most patients are discharged at postoperative day 3-5 and seen again in 2-3 weeks.

• In patients undergoing monoblock or Le Fort III distraction, distraction typically begins at day five at 1 mm/day and is assessed weekly with plane radiographs and clinical examination until the desired position is reached. After advancement a period of consolidation of 1-3 months is recommended before the retractors are removed.
• In patients undergoing conventional advancement with intermaxillary fixation, MMF is kept in place for 4-6 weeks. Routine oral hygiene is prescribed. Patients with arch bars and/or intraoral incisions and/or wounds must be instructed in appropriate oral hygiene procedures. The presence of the arch bars or elastics makes this a more difficult procedure. A soft toothbrush (dipped in warm water to make it softer) should be used to clean the surfaces of the teeth and arch bars. Elastics are removed for oral hygiene procedures. Chlorhexidine oral rinses should be prescribed and used at least 3 times a day to help sanitize the mouth.
  For larger debris, a 1:1 mixture of hydrogen peroxide/chlorhexidine can be used. The bubbling action of the hydrogen peroxide helps remove debris. A Waterpik® is a very useful tool to help remove debris from the wires. If a Waterpik is used, care should be taken not to direct the jet stream directly over intraoral incisions as this may lead to wound dehiscence.

The patient needs to be examined and reassessed regularly and often. Additionally, ophthalmological, ENT, and neurological/neurosurgical examination may be necessary. If any clinical signs for meningitis or mental disturbances develop, professional help has to be sought. Due to the young age of many patients, routing CT-scans are performed only if clinically indicated to avoid excessive radiation exposure.