Module #13

Brian C Toolan, MDShepard Hurwitz, MD

Basic Techniques in External Fixation

Developed by the Surgical Skills Task Force of the American Board of Orthopaedic Surgery (ABOS) in collaboration with the American Academy of Orthopaedic Surgeons (AAOS), and the American Orthopaedic Association (AOA)/Council of Orthopaedic Residency Directors (CORD)

Presentation #1: Indications and Biomechanics

Basic Motor SkillsExternal Fixation

Indications & Biomechanics

Brian C Toolan MDShepard Hurwitz MD

External Fixation

Operative technique for bony realignment and stabilization in trauma and reconstruction

FracturesLimb deformity correction

Arthrodesis

Indications

TraumaOpen Fractures

Severe soft tissue injuryComminution

Bone loss

Temporizing or Definitive means of fixation

Indications

Deformity Correction

CongenitalPost-traumatic

Acquired

Indications

Reconstruction

ArthrodesisMalunionNonunionInfection

External Fixation

Constructs use pins and/or wires connected by clamps to bars and/or rings

Constructs used to apply compression, distraction or neutral forces on bone

External Fixation Constructs

Uniplanar

Biplanar

Circular (Ilizarov)

Hybrid

Advantages

• Simplicity and ease of application

• Minimal blood loss

• Adjustability after surgery

• Access for wound management

Disadvantages• Anatomic structures at risk (Safe Zones)

• Pin/Wire site infections

• Joint contractures

• Prolonged time to bony healing

Safety Factors

Pin/Wire should notbe in the fracture

When drilling go slow as not to burn the bone

Stability Factors

Pin/Wire Location

Maximal pin span

Stability Factors

Pin/Wire Number

More pins distribute forces and increase construct stiffness

Stability Factors

Pin/Wire SizeTorsional strength

proportional to its radius4

Pin core diameter <

1/3 bone diameter

Stability FactorsInsertion Technique

Thread-Shank junctionis weakest point

Insert pin shank toproximal cortex

(2x increased stiffness)(threads = bone width)

Off plane pin insertion

Stability FactorsInsertion Technique

Circular frames

Wires placed at 90o stiffer than at 45o

Increased wire tension stiffens circular frames

Stability Factors

Pre-drilling

Low-speed drilling reduces thermal necrosis

HA coating increases pullout strength

Carbon Fiber Rods

Carbon fiber rods stiffer than steel tubes

Lightweight

Radiolucent

Stability FactorsLower Bone-Rod distance

increases stiffness

In-line stacking increases stiffness

Second sidebar at 90o to first increases stiffness

Spanning External Fixators

Portable Traction

Span intra-articular fracture

Aide reduction through ligamentotaxis

Compression External Fixators

Arthrodesis in the setting of infection

Distraction External Fixators

Limb Lengtheningthrough

Distraction Osteogenesis

1mm / day

Multiplanar corrections

Module #13

Brian C Toolan, MDShepard Hurwitz, MD

Basic Techniques in External Fixation

Developed by the Surgical Skills Task Force of the American Board of Orthopaedic Surgery (ABOS) in collaboration with the American Academy of Orthopaedic Surgeons (AAOS), and the American Orthopaedic Association (AOA)/Council of Orthopaedic Residency Directors (CORD)

Presentation #1: Indications and Biomechanics