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Limb ReconstructionAmir Qureshi
ConsultantUniversity Hospital
Southampton
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What is Limb Reconstruction Surgery?
❖ Recognised Orthopaedic Sub-speciality
❖ Specific clinical orthopaedic problems
❖ Team (surgeon, theatre staff, nurses and physio’s)
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Tools of the trade
❖ traditionally associated with external fixators
❖ however internal fixation devices may also be utilised
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Why an external fixator?
❖ If you cannot cover the wound with soft tissue at the end of the procedure
❖ If you cannot get the ends of the bone together e.g. if bone is missing
❖ If correcting a deformity acutely will risk neurovascular or soft tissue.
❖ to preserve length whilst correcting deformity
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A bit about fracture healing
✤ Physiological process
✤ replaces injured bone
✤ restores biological/mechanical properties
01
Trauma
Disruption of
✤ stability
✤ vascular supply
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Angiogenesis
↑movement at fracture gap = tearing of newly formed vessels = ↓ cap formation
Mechanical Environment
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Mechanical Environment
✤ local forces critical to bone regeneration and healing
✤ Wolff law: remodelling in response to stress & strain
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Strain (movement) influences:
✤ cellular response
✤ formation of capillaries
✤ resultant tissue formed at # site
✤ increased strain affects ability to form capillaries, and hence bone (has high oxygen requirement)
✤ gross instability leads to fibrocartlilage formation
✤ increased stability increases vascularity and bone formation
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No Strain with anatomical reduction is GOOD
No Strain with poor reduction is BAD
Controlled Strain with adequate reduction is GOOD
Excessive Strain beyond limit of healing tissue is BAD
Degree of strain during treatment determines tissue response / type of healing
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Bone Loading
✤ promotes flow through 3-D canaliculi network populated by osteocytes
✤ pulsating fluid releases cell signalling molecules from osteocytes
✤ forms callus
Secondary Fracture Healing
key concept.....
✤ Primary Bone Healing – occurs when there has been anatomical reduction and interfragmentary compression of all fracture fragments ( no motion between fracture surfaces under functional load)
✤ Secondary (Callus) Bone Healing – occurs when there is a controlled degree of motion between fracture fragments, but always lower than the strain limit
1. Haematoma formation & inflammation
2. Soft callus formation
3. Hard callus formation
4. Remodelling
Phases of Bone Healing
2. SOFT CALLUS – formation of fibrous tissue, cartilage, woven (immature bone)increased strain at centre of fracture gap, new vessels can’t form, low oxygen tension.Cartilage formed as has low oxygen requirement
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hard callus phase
✤ cutting cones. remove callus and lay down new bone
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REMODELLING
woven bone remodelled to lamellar bone, medullary canal reforms.
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✤ a frame provides relative stability (controlled strain)
✤ this controlled movement allows callus to bridge the fracture gap
✤ once the callus is strong it will be gradually replaced by bone
✤ we can gradually ‘stretch’ new forming bone (regenerate) to fill in a gap (bone transport) or make new bone (limb lengthening)
Summary
Acute Fractures not amenable to routine surgery
Non Unions
Infection
• difficulttoeradicate• surgicaltreatmentaswellas
medical• Bacterialiedormantin
sequestratedareas• colonisationofinternalfixation• Internalfixationcanfail• Externalfixationprovides
stability• Boneexcision/lengtheningoften
required
Bony angular deformities
Leg length discrepancy – congenital or from injury
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Types of frames
❖ Monolateral (eg Hoffman)
❖ damage control surgery
❖ Circular
❖ classical Ilizarov type frame
❖ Hexapod
❖ TSF/ Orthofix TL Hex
Patients…
✤ Patients are up walking within 48 hours
✤ As there is no ‘rattle’ or strut movement, they have confidence in hardware
✤ Similarly physio’s are confident in pushing mobilisation
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