Mandibular and maxillofacial fractures Flashcards
What are the goals of maxillofacial fracture repair as per Vallefuoco 2021 in JSAP?
Restoration of occlusion, stabilize the major skeletal supports, restore the contour of the face and achieve proper function and appearance.
What implant is depicted here for the use in caudal mandibular fractures as described by McFadzean 2024 in JFMS?
Ramus Anatomical Plate design
Label the bones of the mandible.
Fractures of the ramus of the mandible, condyloid (condylar) process or mid-facial skeleton are best observed using which imaging modality?
CT
What is the difference between the mandible and long bones of the body?
The mandible does not have a medullary canal.
The maxillary bones have a higher vascularity as compared to the mandible, and heal in a more similar fashion to long bones.
What type of bone healing is preferred in maxillofacial repair?
Direct bone healing with anatomic reduction and absolutely rigid fixation.
Why is removal of teeth not recommended at the time of maxillofacial/mandibular fracture repair unless the involved teeth are loose or cannot be stabilized?
Disruption of the blood supply and iatrogenic trauma to adjacent tissues (including further displacement of the fractured bone fragments), elimination of occlusal landmarks useful in realigning bone segments, elimination of available structures for use in the fixation of bone fragments, and creation of a large bony defect.
Does disruption of the inferior alveolar artery within the mandibular canal affect the teeth?
No.
What is the order in which injuries to the jaw should be treated?
Inside-to-out: bone first, then teeth, then soft tissues, then treatment of specific dental injuries (restoration).
When should vital pulp or root canal therapy be considered in instances of jaw fracture?
If there is a fractured tooth. Vital pulp therapy is used to preserve the pulp (generally performed initially). Root canal is performed if the tooth loses vitality.
What is the effect of severe periodontal disease on oral fracture management?
Periodontal disease can cause significant loss of alveolar bone which can complicate fixation, it can also inhibit healing (resulting in nonunion and fixation failure).
A rostral mandibulectomy may be the only option in some cases.
What is the tensile and compressive surfaces of the mandible?
Tensile surface is the oral surface, compressive surface is the aboral surface.
The ramus experiences maximum shear forces, and the symphysis experiences maximum rotational forces.
What are the primary buttresses of the maxillofacial skeleton?
- Rostral (medial, nasomaxillary).
- Lateral (zygomaticomaxillary).
- Caudal (pterygomaxillary).
The caudal buttress is not readily accessible.
Facial frame reconstruction can be performed using how many of the three buttresses?
Two of the three buttresses. The caudal is relatively inaccessible, so repair is normally focused on the lateral and caudal buttresses.
The incisive bone does not require repair as it does not provide essential support to the skull.
What are the advantages/disadvantages of plate placement along the alveolar margin?
Advantage is that it is on the tensile surface of the mandible.
Disadvantage is that avoiding tooth roots is challenging. Penetration of a tooth root can result in death, although clinical relevance still relatively undetermined.
Intubation for oral fracture repair while allowing assessment of dental occlusion may be optimized through use of what?
A pharyngostomy for intubation.
What are the surgical approaches for various oral surgeries?
Mandible: ventral. Lateral may be required for access to the TMJ.
Maxillofacial: direct incision over the affected area or via an incision in the alveolar gingiva. Mandibular fractures should be performed first to provide a template for maxillofacial repair. Temporary maxillomandibular fixation ensures appropriate occlusal realignment during repair. Lateral buttresses should be repaired first, followed by medial.
Zygomatic arch/orbit: direct approach.
Intraosseous wire is only appropriate for repair of which fractures?
Reconstructable fractures of the mandible. Only effective in neutralizing tensile forces (should be placed along alveolar bone margin).
Cannot be used for reconstruction of maxillofacial fractures involving the buttress supports, as compression is the primary force acting in these areas which wiring will not counteract.
What intraosseous wiring techniques may be helpful in maintenance of reduction of maxillofacial fractures (excluding the buttress support systems)?
Wiring of maxillofacial segments may be challenging due to thin monocortical bone or bone curvature. Two wiring techniques may aid in overcoming these difficulties:
1) Skewer pin technique.
2) Pin splint technique.
What are the advantages of miniplate systems for repair of mandibular and maxillofacial fractures?
- Small size allows placement along maxillary buttress supports.
- Small screw size and thread pitch allows for bone purchase even in areas of thin bone (the thread pitch of a screw cannot be larger than the diameter of the screw to achieve bone purchase). The thread pitch of miniplate systems is between 0.5 - 1mm, and the thickness of maxillofacial bone is typically 1-2mm.
- Screws can be angled to avoid tooth roots while allowing placement along the tensile alveolar surface of the mandible.
- Easily contoured.
What are three miniplate systems that can be used for maxillofacial reconstruction?
- Martin miniplate.
- Synthes maxillofacial system.
- ALPS (can use locking or cortical screws).
All plates are made from Titanium and can be bent in or out of plane. Screw heads can be angulated up to 20 degrees.
Care must be taken when inserting small titanium screws as shearing of the screw head is possible with over-torque. Tapping may be preferable.
What is the function of the second ventral miniplate application on the mandible (in addition to the miniplate applied along the alveolar portion of the bone)?
To counteract shear and torsional forces (the alveolar miniplate is only effective in counteracting bending).
In comminuted mandibular fractures addition of a second, larger ventral buttress plate using a 2.4 or 2.7mm DCP, LC-DCP or LCP may be preferred over a miniplate.
What can be used to provide additional support to plate fixation of the mandible in instances of large bone loss?
- Cortical bone graft from the ulna or rib(s) (typically supplemented with a cancellous autograft) and compression plating. Should not exceed 40 mm to prevent failure of revascularization and collapse.
- Locking plate fixation (stabilization plate) with regular plate fixation of the alveolar margin (tension plate) and addition of osteoinductive materials (autogenous cancellous bone graft, demineralized bone matrix) or growth factors (rhBMP-2).
How are fractures of the ramus of the mandible repaired?
Tension band plate placed along the coronoid crest and stabilization plate placed along the condyloid crest (thicker bone in these regions). Locking plates can be applied in both instances.
What are repair options for fracture of the condyloid process?
Condylectomy or lag screws.
