Mandibular reconstruction Flashcards
Indications for mandibular reconstruction
- Segmental defect of mandible following tumor ablation
- Chronic osteomyelitis of the mandible or comminuted nonhealing mandible fx
- Acquired or congenital malformation of the mandible
What factors must be considered in reconstructing the mandible?
- Length and location of mandibular defect
- Associated soft tissue loss
- Overall health and well being of pt
- Pt’s prognosis
- Potential donor sites
- Primary vs delayed repair
- Pt’s dental health and potential for dental rehab
Reconstructive options
- No reconstruction (i.e. close the surrounding soft tissue over the defect for one or two free swinging mandibular segments) –> “Andy Gump deformity”
- Soft tissue closure
- Alloplastic implants
- Alloplastic trays
- Vascularized bone
- Free tissue transfer
- Distraction osteogenesis
- Bone generation
Alloplastic implants
Include steel, titanium, and other alloy (vitallium)
Fashioned into either a bar or tray
Conformed to shape of missing piece
Titanium is m/c bc retains strength, biocompatibility, rigidity, can be contoured in OR
Adv: rapid, effective recon without donor site defect
Disadv: Implant fracture, plate extrusion and infection, exposure after radiation
Indications: lateral mandibular defect
Don’t use for anterior defects
Alloplatic trays
Trays are filled w/ bone chips that serve as scaffold for osteoblasts to create new bone
Bone growth is unpredictable and unreliable
Irradiated fields create an additional impediment to good bone healing
50% or more pts have unsatisfactory results
Vascularized bone – pedicled bone flaps
- Clavicle on SCM/trap/or deltopec. mixed success bc blood supply unreliable and random
- Pec w/ 5th rib. Better but still unreliable.
- Rib grafts off lat. Too much bulk and not enough bone.
- Spine of scapula onto trap. Best pedicle option. 10 cm of bone. Fair reliability.
Vascularized bone – free tissue transfer
Best results for mandib recon
Difficult to decide whether to use for small defects
Options:
1. Radial forearm
2. Scapula (only option where 2nd team can’t harvest simultaneously)
3. Iliac crest
4. Fibula
Radial forearm flap
Radial artery
Vena comitans of radial art or cephalic vein
10 cm of bone (but not thick bc only 1/3 of cross-section is taken so less future risk for radial bone stress Fx)
Indications: large amount of soft tissue needed but only a small segmental mandibular defect (i.e. low bone need)
Bone cannot support osseointegrated implant
How to reduce risk of postop radial bone Fx after radial forearm flap harvest
- Only harvest 1/3 of the cross sectional area
- Taper the edges of the graft in a “boat tail” fashion
- Prolonged immobilization of the arm in a splint (3 wks or longer)
Scapular flap
Circumflex scapular system (subscapular art)
2 venae comitantes
12 cm of bone
Most independently mobile soft tissue components and large amount of soft tissue available
Bone can support osseointegrated implant
Disadv: Need to change pt from supine to lateral position for harvest (i.e. no simultaneous harvest)
Iliac crest flap
Deep circumflex iliac artery
Deep circumflex iliac vein
Can reconstruct 3/4 of the mandible
Natural iliac curvature approximates natural mandible shape
Bone is thick and can accept osseointegrated implant
Gives thick, nonpliable skin flap +/- internal oblique muscle
Indications: 1. through & through defect of lateral mandible and cheek
2. Near-total glossectomy w/ mandibulectomy
Fibular flaps
M/c used flap for mandibular recon
Peroneal artery
Peroneal vein
25 cm of bone (leave 8 @ prox and distal ends for joint stability)
Reliable skin paddle
Soft tissue available (flexor hallucis longus)
Periop vascular imaging helpful
Sensory reinnervation possible via lateral cutaneous branch of peroneal nerve
Distraction Osteogenesis
New technique
Appliance is attached to mandible and a thin piece of the end of the mandibular segment is cut free from the rest of the mandible. It is slowly advanced through use of a “key” attached to the appliance.
The space b/w the advancing segment and the bulk of the mandible is filled with new bone.
Once enough new bone, the free ends are roughened and then the remaining segments are plated
Takes time
Indications: congenital mandibular insufficiency
Bone generation
Creating new bone using growth factors and hydroxyapatite mixtures
Complications of mandibular reconstruction
- Flap failure
- Fistulas (small areas of dehiscence can lead to salivary fistula w/ vascular risk)
- Donor site morbidity (sensory and motor nerve damage, gait abnlities)
- Extrusion of alloplastic materials
