Computer-assisted surgery in orbital reconstruction and facial trauma

Question 1

What is the starting point for surgery related to facial trauma?

Answer 1

• Multidisciplinary approach
• With the oral and maxillofacial (OMF) surgeon in charge
• The OMF surgeon is the main contact for the trauma and/or neurosurgeon.

Question 2

What is the definition of facial trauma?

Answer 2

Injury of the viscerocranium (injury to dentition, hard or soft tissue)

Question 3

There are four urgent indications for surgery due to facial trauma. What are these?

Answer 3

• Airways
• Blood los
• Eyes
• Teeth

Question 4

What are Le Fort Fractures of the skull?

Answer 4

Le Fort performed tests by throwing cadaver heads to the ground at different angles and forces. He determined that predictable patterns of fractures are the result of certain types of injuries, and concluded that there are three predominant types of mid-face fractures.

Question 4

What can be used to get an idea about where the bones are dislocated and how they can be reconstructed?

Answer 4

Mirroring

Question 5

Why are bilateral fractures most difficult to reconstruct?

Answer 5

Because mirroring cannot be used to get an idea about the location and reconstruction of the fracture.

Question 6

What is used to improve planning for the next patient?

Answer 6

Evaluation

Question 7

What is challenging regarding surgery of orbital fractures?

Answer 7

• Complex region
• Need for extra control
• Unpredictable
• Many revision surgeries
• Proof-of-principle
• True entrapment is rare
• Forced duction test
• Fast intervention necessary (<6 hr)

Question 8

• What is an orbital trapdoor fracture?
• What is an orbital blow-out fracture?

Answer 8

• A minimally displaced fracture of the orbital floor that has spontaneously reduced to its original position incarcerating an extraocular muscle.
• An orbital blowout fracture is a traumatic deformity of the orbital floor or medial wall that typically results from the impact of a blunt object larger than the orbital aperture, or eye socket. Most commonly, the inferior orbital wall, or the floor, is likely to collapse, because the bones of the roof and lateral walls are robust.

Question 9

What is the meaning of enophthalmos?

Answer 9

Eye dropped back into socket

Question 10

What is the goal of orbital reconstruction?

Answer 10

• Restore globe position
• Restore orbital volume
• Recover function

‘Restoration of the orbital contour is the first and probably most predictable step in orbital reconstruction’

Question 11

What are obstacles of orbital surgery?

Answer 11

Key hole surgery → very limited overview

Question 12

What is the difference between a conventional workflow and a computer-assisted surgery (CAS) workflow?

Answer 12

• Conventional workflow → diagnostics → surgery → evaluation
• CAS workflow → diagnostics → advanced diagnostics → virtual surgical planning → surgery and intraoperative feedback → evaluation

Question 13

For what are splints used?

Answer 13

To indicate registration points without invasive bone-anchored screws.

Question 14

How does a CT-scan work?

Answer 14

The patient lies on a bed that slowly moves through the gantry while the x-ray tube rotates around the patient, shooting narrow beams of x-rays through the body.
The patient is subdivided in volume elements (voxels, 3D pixels) and then the absorption of each voxel is calculated through back-projection.

Question 15

ACOR = Advanced Concepts in Orbital Reconstruction

Question 16

How can personalized medicine be applied in regard to orbital surgery?

Answer 16

Patient-specific implant design in complex cases. With this approach, each patient is their own prototype

Question 17

What can be used instead of the costly navigation systems in the OR?

Answer 17

Real time navigation with e.g. VR glasses.

Question 18