15.1 The three questions
Bone reconstruction can be summarized as three questions to ask about any bone defect:
- Is it stable? If not, provide fixation.
- Does it have a blood supply? Look at the bone ends and the soft tissue cover. If not, bring vascularized tissue: a flap or vascularized bone.
- What is missing: cells, signal or scaffold? Choose the graft that supplies it.
Flowchart: Approach to a bone defect
- Bone defect
- 1. Is it stable?
- No → fixation
- 2. Is there a blood supply and soft tissue cover?
- No → flap cover or vascularized bone
- 3. What is missing?
- Small defect, good bed
- Cancellous autografthealing
- Cortical graft or implantshape
- Large defect or poor bed
- Vascularized bone flap
- Induced membrane or bone transport
- Bone and soft tissue too short
- Distraction osteogenesis
- Small defect, good bed
- 1. Is it stable?
15.2 The options, from simple to complex
| Option | When it is suitable | Example |
|---|---|---|
| 1. No bone reconstruction | The defect can heal by itself, or continuity is intact | Skull defect in an infant; marginal mandibulectomy |
| 2. Cancellous autograft | Small, contained, stable defect in a healthy bed | Alveolar cleft; small nonunion |
| 3. Cortical autograft, or an implant | Shape is needed, with little load, under good soft tissue | Orbital floor, nasal dorsum, cranioplasty |
| 4. Distraction or induced membrane | Soft tissue is short, or a segmental limb defect | Small mandible in Pierre Robin; tibial defect |
| 5. Vascularized bone flap | Long defect, load-bearing, irradiated or contaminated bed | Segmental mandible; long bone; scaphoid with avascular pole |
| 6. Combined methods | Very large or complex defect | Fibula with allograft; epiphyseal transfer in a child |
We do not always start at option 1. We choose the simplest option that will work for that defect and that bed.
15.3 Worked examples
| Patient | Stable? | Blood supply? | What is missing | Reconstruction |
|---|---|---|---|---|
| 9 cm segmental mandibular defect after ameloblastoma resection | Needs plate fixation | Bed is contaminated by saliva; defect too long for a graft to revascularize | Living bone and lining | Free fibula osteocutaneous flap |
| Open tibial fracture, Gustilo IIIB | External fixator or nail | No: periosteum and soft tissue lost | Soft tissue cover first; bone later if there is a defect | Early flap cover; bone graft or induced membrane later |
| Scaphoid nonunion with avascular proximal pole | Needs screw fixation | No: proximal pole is dead | Blood supply and structure | Vascularized bone graft (medial femoral condyle) |
| Alveolar cleft, age 9 | Yes | Yes | Cells and scaffold | Iliac cancellous bone graft |
| Neonate with Pierre Robin sequence and airway obstruction | Yes | Yes | Bone length and soft tissue | Mandibular distraction |
| Adult with large skull defect after craniectomy | Yes | Dura and scalp only | Shape, under reliable soft tissue | Custom implant or split calvarial graft, after making sure the scalp cover is good |
15.4 Key points
- Bone healing needs stability and blood supply.
- A graft supplies cells, signal or scaffold. Only autograft and vascularized bone supply living cells.
- Cancellous graft for healing; cortical graft for shape.
- Vascularized bone for long defects and poor beds.
- Allograft and substitutes are scaffolds; they depend on the bed.
- Implants depend on their soft tissue cover.
- Distraction grows bone and soft tissue together.