External fixation ali sarhan
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Transcript of External fixation ali sarhan
By : ali sarhan
External fixation is a surgical treatment used to stabilize bone and soft tissues at a distance from the operative or injury focus.
external fixator includes : 1. Schanz pin 2. Connecting rods 3. Clamps.
Schanz pins
Connecting rods
Indications severe open fractures
Infected fractures
Correction of extremity malalignments and length discrepancies
Initial stabilization in poly trauma patients
Closed fracture with associated severe soft tissue injuries
Severely comminuted diaphyseal and periarticular lesions
Temporary transarticular stabilization of severe soft tissue and ligamentous injuries
Pelvic ring disruptions
Certain pediatric fractures
Arthrodesis
Osteotomies
Malunion/nonunion
Advantages1. Minimally invasive
2. Flexibility (build to fit)
3. Quick application(emergency)
4. Useful both as a temporizing or definitive stabilization device
Disadvantages
Mechanical
1. Distraction of fracture site2. Inadequate immobilization3. Pin-bone interface failure4. Weight/bulk5. Refracture (pediatric femur)
Biologic
1. Infection (pin track)2. Neurovascular injury3. Tethering of muscle4. Soft tissue contracture
May result in malunion/nonunion,
loss of function
Pins Principle: The pin is to link between the
bone and the frame
Pin stiffness is determined by its diameter.Pin insertion technique respecting bone and
soft tissue
Various diameters(Commonly from 3 to 5 mm.), lengths, and designs
MaterialsStainless steelTitanium (More biocompatible , Less stiff ) .
‘Blunt’ pins- Straight
- Conical
Self Drilling
Pin coatings
Recent development of various coatings (Chlorohexidine, Silver, Hydroxyapatite)
1. Improve fixation to bone2. Decrease infection
Pin Insertion Technique1.Incise skin2.Spread soft tissues to bone3.Use sharp drill with sleeve4.Irrigate while drilling5.Place appropriate pin using sleeve
Avoid soft tissue damage , and bone thermal necrosis that created by the drilling
Pin Length
Half Pinssingle point of entryEngage two cortices
Transfixation PinsBilateral, uniplanar fixationMore stable Limited anatomic sites ( injury )
Pin Diameter GuidelinesFemur – 5 or 6 mmTibia – 5 or 6 mmHumerus – 5 mm Forearm – 4 mmHand, Foot – 3 mm
< 1/3 dia
Clamps Two general varieties:
Single pin to bar clampsMultiple pin to bar clamps
Connecting Rodsmaterials:
○ titanium○ Steel○ Aluminum○ Carbon fiber
Design○ Simple rod○ Articulated○ Telescoping
Ring Fixators
Useful for correction of: (Reconstruction)LengthAngulationrotation
MRI Compatibility Stainless steel most at risk for attraction and
heating
Titanium ,aluminum and carbon fiber demonstrate minimal heating and attraction
Almost all are safe if the components are not directly within the scanner.
Biology
Current External fixation systems have been designed to allow micromotion at the fracture site to promote callus formation
Stable yet less rigid systems of external fixation maintain alignment and length while allowing and actually encouraging beneficial micromotion
Micromotion = rigid stability
Anatomic Considerations Avoidance of major nerves,vessels and organs
(pelvis) is mandatory
Avoid joints and joint capsules Proximal tibial pins should be placed 14 mm distal to articular surface to
avoid capsular reflection
Minimize muscle/tendon impalement
Lower Extremity “safe” sites
14 mm
Upper Extremity “Safe” Sites
Humerus Proximal: axillary n Mid: radial nerve Distal: radial, median and ulnar n
Ulna: safe subcutaneous border, avoid overpenetration
Radius Proximal: avoid because radial n Mid and distal : sup. radial n.
In the upper extremity dissection is In the upper extremity dissection is recommended to avoid neurovascular injury.recommended to avoid neurovascular injury.
Conversion to Internal Fixation
Generally safe within 2-3 wks
Plates are good choice
Use with caution with signs of pin irritation (Consider staged procedure )
Extreme caution with established pin track infection
Pin-track Infection Prevention
Pins placed in subcutaneous bone borders
Pins placed away from zone of injury
Use of adequate skin incision
Use of sharp drill bits to prevent thermal necrosis
Postoperative care:
Clean implant/skin interfaceSalinegauze around pins to hold skin down to
prevent excessive motion at pin/skin interface Shower (only after wounds are healed)
Stage I: Seropurulent Drainage
Stage II: Superficial Cellulitis
Stage III: Deep Infection
Stage IV: Osteomyelitis
Pin-track Infection Treatment of Pin-track infection should consist of:
Stage I: aggressive pin-site care and oral cephalosporinStage II: +/- Parenteral AbxStage III: Parenteral Abx plus removal of pin
Stage IV: same as Stage III , culture pin site for offending organism, specific IV Abx for 10 to 14 days, surgical debridement of pin site