Download - External skeletal fixators
External skeletal fixation techniques
Shahnawaz ahmad bhat
4857
Definition
A method of fracture treatment ,that involves the percutaneous placement of a series of transcortical pins or wires , which are externally connected to a rigid frame
Indications for use Long bone fractures
Open fractures
Comminuted fractures that cannot be anatomically reconstructed
Osteomyelitis
High-energy fractures with soft- tissue injuries and vascular compromise
Cont’d........
Transarticular ESF in arthrodesis
Temporary splintage during healing of soft tissue or osseous structures
Nonunion / with bone graft
Corrective osteotomy for antebrachial /tibial growth deformities
Limb lengthening procedures
Cont’d……
Conjunction with internal fixation- in humeral, femoral or tibial fractures
Hybrid ESF system- humeral, radial or tibial fractures with very short distal or proximal fragment
Cont’d….. Mandibular or maxillary
fractures- usually with acrylic fixators
Lubosacral fractures & luxations
Avian limb fractures
Fracture repair in small exotic mammals
Advantages of ESF
Minimally invasive method, preserving blood supply & soft tissues
No implants at the fracture site Possible closed application which limits iatrogenic trauma Provides immediate wt. bearing after surgery Maintains normal joint mobility Provides optimum environment for osteosynthesis & wound
healing compatibility with internal fixation devices Technical ease of application and removal wound management in open fractures Reusability of the pin clamps & connecting bars
Disadvantages of
ESF Device must be cleaned and monitored regularly Care to prevent additional damage to
animal/device
Aftercare is more labor intensive
More rigid type II and III frames cannot be used for fractures of femur & humerus
Difficult to apply and more pain in areas of increased muscle mass
Extremely high cost
ESF FRAMES
LINEAR
CIRCULAR
HYBRID
Equipment
ESF
3 BASIC UNITS
FIXATION PINS EXTERNAL CONNECTORS
LINKAGE DEVICES
Inserted into bone To hold major
Fragments Support fractured
Bones
Attach fixation Pins & external
Connectors
FIXATION PINS : classification
on basis of implantation method
HALF PIN penetrate only one skin surface but both bone
cortices
FULL PINPanetrate one skin surface then both cortices ,and then the opposite Skin
Surface
On basis of structural design Smooth pin :
Rely on friction to remain stable in the bone
Threaded pins: Positive profile and negative profile Centrally threaded and end threaded
Positive & negative profile threaded pins
Pins in which core diameter of the threaded section is smaller than the diameter of the smooth section have negative thread profile
If the core diameter is consistent b/w smooth & threaded regions ,thread profile is positive
Positive profile transfixation pins used in ESF
Centrally threaded & End threaded pins
Centrally threaded pins are used as full pins with type ÌÌ or ÌÌÌ external fixator frames
Central threads engage bone & smooth pin ends extend beyond the skin surface
End threaded pins are described a/c to no. of cortices engaged by threads (one cortex & two cortex end threaded pins)
End treaded pin Centrally threaded
pin
External connectors
Made up of stainless steel, titanium alloy , carbon fiber,aluminium or acrylic
External fixator & linkage devices may be fashioned from acrylic for ACRYLIC -PIN EXTERNAL FIXATOR (APEF)
APEF system contains +ve profile threaded fixation pins ,packaged acrylic & sterilized acrylic column molding tubes
SK double clamp
Secur-U clamp
S K single clamp
Kirschner double clamp
Kirschner single clamp
Kirschner type linkage devices for joining fixation Pins to external connecting bars & external connecting
bars to each other.Note the larger holes for the external connecting bars & smaller holes in the bolts for
Fixation pins
Linkage devices
Linear ESF Configurations
Type Ì ,ÌÌ or ÌÌÌ configuration
TYPE Ì Configuration Utilize half pin splintage fixation pins Connecting frame placed on only one side of the
limb Unilateral constructs Classified as *type Іa (unilateral and uniplanar) *type Іb (unilateral and biplanar)
Type Ǐa (unilateral –uniplanar ) fixators
All the fixation pins & connecting frame occupy a single plane (uniplanar)
Usually applied to cranial medial surface of radius/ tibia and lateral surface of femur/ humerus
Fixation pins are half pins
Type Ǐb (unilateral -biplanar ) fixators
Applied most often to radius & tibia
For radius & tibia–one ext. bar is placed on craniomedial surface & 2nd bar on craniolateral surface
Type ǏǏ (bilateral-uniplanar ) fixators
Utilize full pin splintage fixation pins
Cannot be placed on femur/ humerus because of adjacent body wall
Applied only to radius/tibia in mediolateral plane
Maximal type ІІa & minimal type ІІb
Maximal type ІІa
Minimal type ІІb
Type ǏǏǏ(Bilateral-biplanar)fixator
Combination of type І and type ІІ
Type І and type ІІ systems placed approx. 90° to each other
Can’t be applied to femur or humerus
Indicated in very large dogs
TIE-IN CONFIGURATION Combination of ESF (type Іa or Іb) with
intramedullary pin
Increases rigidity of fracture fixation in humerus & femur as type ІІ &Type ІІІ frames cannot be applied
No. of fixation pins is limited to 2 or 3 pins above & below the fracture
Tie –in configuration
Biomechanics Fixator rigidity depends on: Type of configuration- Type ІІІ > type ІІ > type І biplanar type Іb more resistant to
cranial/caudal shear forces compared with type ІІ.
Number of used pins: at least 2 & up to 4 pins/bone segment
Diameter and design of the pins – the diameter ≤ 25 % of the bone’s diameter
The fixator rigidity by widening pin spacing within pin groups & by the distance between pin groups
The most central pin should be 1-2 cm away from the fracture line
Cont’d…..
Moving the connecting bar closer to the bone makes the pins more resistant to bending
Using a “tie-in” configuration increase significant in bending strength
Fixation pin application Preoperative planning
Patient fracture assessment
Most important principle -asceptic surgery
Injured limb suspended from hook in the ceiling Patient Draping
choose a surgical approach Delimitation of safe corridors for insertion of pins
Cont’d……..
Most proximal and distal pins inserted after a stab skin incision
Predrilling a pilot hole with slightly smaller diameter drill bit
Transfixating pins inserted by using low-speed power drill
Fracture reduced & connecting bar connected to proximal and distal pins by clamps
Clamps placed 1-2 cm away from the skin surface
Central pins are inserted above and below the fracture
Rest of needed pins inserted & bolts tightened
Postoperative management Postoperative analgesia Pin-skin interface cleaned with antiseptic
solution Incision around pins released/extended in
case of skin tension Sterile gauze sponges placed around &
b/w fixation pins Limb wrapped with vetrap (bandage
material ) Activity restricted to least walking &
physical rehabilitation
Circular External Skeletal Fixators(CESF) (Ilizarov technique)
Most recent innovation in ESF technique in dogs and cats & also in large animals.
Developed by the Russian physician Gavriil A. Ilizarov
CESF consist of a series of complete and/or incomplete external rings that are interconnected by a series of threaded rods
Cont’d…..
These are modular systems which can be assembled in numerous configurations to
stabilize fractures and arthrodeses, perform bone lengthening and transport correct angular, translational and rotational
deformities
Each ring is secured in position along the rod by placing a nut on either side of the ring
Cont’d….
Elongation of the frame allows for distraction osteogenesis in which regenerate bone is produced within the gap created when an osteotomy is distracted slowly and sequentially
“Discontinuity of a skeletal segment necessarily triggers the repair process which will continue as long as integrity of both osteogenic tissue & its vascular supply is maintained”
Traditional CFs use small diameter wires, rather than pins, as fixation elements
Standard circular fixator frame for fracture management
Bones can be lengthenedby streching a corticotomy
1mm a day The regenerate is composed of Microcolumns originating from
both bone ends
Radiograph of distraction Callus at 3 wks
Regenerated bone appears in the trailing pathway of a
distracted bone segment in the dog treated with bone resection
& distraction osteogenesis
Equipment
Wires Rings Wire fixation bolts Threaded rods Nuts Wire tensioner &
wrenches
Wires :
1.0,1.2 or1.5mm diameter used in cats/ dogs Olive wires- wires with a bead positioned
midway along the wire Provide interfragmentary compression &
increase stability of frame construct more the no. of fixation wires- more stability
of fixation Wire angles < 45°should be avoided
Olive wires
Rings
Partial ring & full ring Five–eighth/stretch ring are used when rings
would limit joint motion (elbow/stifle) Partial rings -versatile Full rings -more available holes for rods &
wire, not versatile ring diameter , axial stiffness, torsional &
bending stiffness Smallest ring allowing ≥2 cm distance b/w skin
& inner circumference of ring selected
Wire fixation bolts Cannulated wire fixation bolts –allow wire
passage via a concentrically placed hole at base of bolt head
Slotted wire fixation bolts have an eccentric slot located under the bolt head & parallel to its long axis
Wire must be fixed without deformation
Frame construction Threaded rods used to connect rings & form
frame
Telescopic rods- hollow rods used as supports & connecting elements of ring
Frames are constructed so that one ring & its wires are placed at proximal end and another ring & its wires are placed at distal end of long bone
2 additional rings placed so that their wires panetrate proximal & distal bone segments close to the fracture
Wire tensioner
Hybrid External Fixator
Combination of a ring & a linear fixator
Indicated for fractures with juxtaarticular bone segments
May be applied to radius,tibia,femur & humerus
Can also be used to stabilize corrective osteotomies for angular limb deformities
Larger transfixation wires can be combined with the
use of rings & wires in a Hybrid frame
Clinical Applications of ESF
Fracture fixation Radial & tibial
Humeral & femoral Mandibular & maxillary
Stabilization of spinal fractures & luxations Arthrodesis Bone lengthening Bone transport for bone defects Angular limb deformity correction
Fixation of spinal fractures & luxations
Spinal arch external fixator components developed for spinal stabilization
Fluoroscopically guided percutaneous pin placement can be performed when applying external skeletal spinal fixation
Bone transport (limb salvage)
Method by which one or two segments of normal bone adjacent to a defect are slowly transported into the defect while new bone forms in the distraction pathway
Used in dogs with radial/tibial neoplasia or severe osteomyelitis with bone loss
A segment of bone is created with a corticotomy made 2-3 cm from one end of one of the main fragment
Acrylic external fixation
Acrylics are commonly used for the repair of fractures
The acrylic column acts as both the connecting rod and transfixation pin-gripping device Dental acrylic or hoof repair acrylic are suitable It can be moulded over pins after curing to a dough stage Acrylic ESF offers the advantage of reduced cost , improved versatility & simplified application
technique when compared with kirschner ESF
Advantages of acrylic system
Ability to contour the connecting bar to match any fracture configuration
Fixation pins of any diameter may be used
Fixation pins do not have to be in the same longitudinal plane
Light in weight encouraging earlier return to function
cont’d…… Placing the
positive profile threaded pin without the difficulties of passing them through clamps
Inexpensive system
Uses of acrylic fixators
Fixation of mandibular & maxillary fractures
Fixation of long bone fractures
Primary fixation device or intra-oral splint for mandibular & maxillary frcatures
Complications of ESF
Pin tract infection Focal osteomyelitis Ring sequestrum Premature pin loosening Instability at the fracture site Pin breaking Pin tract osteolysis Pressure necrosis of skin Iatrogenic bone fracture soft tissue impalement