external fixation re

RE
BAGIAN ORTOPEDI &TRAUMATOLOGI FAKULTAS KEDOKTERAN UNHAS MAKASSAR
21 mei 2018

 External fixation is a device placed outside
the skin which stabilizes the bone fragment
through wire or pins connected to one or
more longitudinal bar/tube
AO Principles of Fracture Management. 2000

 Hippocrates an external “shackle” device
(> 2,000 years old)
 acute fracture care:
 Provisional fixation :
▪ “damage control”
▪ Periarticular fracture stabilization
 definitive
External Fixation: Principles and Applications. JAAOS. Nov 2015,Vol 23, No 11

 Less damage to blood supply of
bone
 Minimal interference with soft-
tissue cover
 Useful for stabilizing open fractures
 Rigidity of fixation adjustable
without surgery
 Good option in situations with risk
of infection
 Requires less experience and
surgical skill than standard ORIF
 Quite safe to use in cases of bone
infection
 Pin and wires penetrating the soft
tissues
 Restricted joint motion
 Pin-track complications in long-
lasting external fixation
 Cumbersome and not always well
tolerated
 Limited stiffness in certain locations
(e.g., femur fracture in adults)

1. Open Fracture
 Particular those with severe soft tissue injury
 Can be applied with minimal trauma, avoiding additional damage to soft tissues
and bone vascularity
2. Closed Fracture
 Temporary bridging in severe polytrauma and severe closed soft-tissue contusions
or degloving
3. Polytrauma
 For damage-control surgery in polytrauma (ISS > 25)
 The safest way to achieve initial stabilization of fractures in the severly injured
(ISS > 40)
 Can be performed rapidly, minimally invasive technique, minimize any additional
surgical insult to the patient

4. Articular Fractures
 Recommended in cases of open or closed articular
fracture with severe soft-tissue compromise, when it
can be applied in a joint-bridging fashion
5. Bone or soft-tissue loss
6. External fixator as a tool for indirect reduction
 One way to achieve minimally invasive intraoperative
reduction is to apply the modular external fixator as
an external reduction device

 Pins
 Bar/rod
 Clamps
 Construc design

 Schanz screws are partially threaded pins
 Available in different diameters and lengths
(shaft & threaded part) and with different tips
 Standard screws have trocar-shaped tips 
require predrilling
 Available in steel, titanium, or with a
hydroxyapatite coating

 for definitive fixation,
 placing one pin as close to the fracture as possible,
 another pin placed as far from the fracture as possible within the same
bone
 for provisional stabilization,
 potential areas for future definitive fixation should be considered and
avoided,
 prevent the occurrence of deep infection arising from pin tracts
 Decreased pin stiffness  causes increased stress at the pin-bone
interface  leading to micromotion and ultimate pin failure

 to minimize the risk of creating a substantial
stress riser that leads to a possible fracture, the
pin should not exceed one-third diameter of the
bone
 hydroxyapatite-coated pins provide a
significantly improved pinbone interface and a
greater extraction torque compared with
uncoated pins

 The single most important factor with frame
strength is increasing pin size
 Frame bending stiffness proportional to radius⁴
 Example 5mm pin is 144% stiffer versus 4mm
pin
Use the
largest size
pin that is
appropriate
4mm
VS
5mm
Principles of External Fixation. Kemper. OTA. Oct. 2014

Many options
 2-6mm sizes
 Self drilling/tapping
 Blunt tip
 Conical
 Fine thread
 Course thread
▪ Cancellous bone
Material
 Titanium
 Stainless
Coatings
 Non-coated
 Titanium
 Hydroxyapatite

GENERAL GUIDELINES
Femur – 5 or 6 mm
Tibia – 5 or 6 mm
Humerus – 5 mm
Forearm – 4 mm
Hand, Foot – 2.5-3 mm
Avoid unicortical pin

 Self drilling pin
 Advantages
 Single stage insertion
 Fast
 OK for short term use
 Disadvantages
 Short drill flutes resulting in possible
▪ Thermal necrosis
▪ Stripping near cortex
▪ Loss of radial pre-load
▪ Decreased torque to pull out over
time (loosening)

Blunt Pins
 Multi stage insertion
 Preservation of near cortex
 Tapered pins
 Improved radial pre-load
 Beware of advancing and
then backing up, loss of
radial pre-load with early
loosening
Thermal necrosis possible with any type of pin. Irrigate
and adhere to proper technique with insertion.

 Hydroxyapatite (HA) vs titanium vs uncoated
 HA with superior retention of extraction torque
 Decreased infection
▪ 0/50 pts in pertrochanteric region (Moroni JSBS-A, 05’)
 13x higher extraction torque vs uncoated
 2x higher extraction torque vs titanium
 Insertion torque and extraction torque equal with HA coated
pins
 Highly consider HA pins for extended use and or definitive
fracture care.
 Possible future coatings
 Bisphosphonate
 Antibiotic coated
Moroni A, et al,Techniques toAvoid Pin Loosening and Infection in External Fixation. JOT. 16: 189-195, 2002
Moroni A, et al, Dynamic Hip Screw versus External Fixation forTreatment of Osteoporotic Pertrochanteric
Fractures, J Bone Joint SurgAm. 87:753-759, 2005. Principles of External Fixation. Kemper. OTA. Oct. 2014

1. Incise skin
2. Spread soft tissues to bone
3. Triple sleeve first in and last out
4. Irrigate while drilling
5. Place appropriate pin using
sleeve
6. Place pin bi-cortical
Avoid soft tissue damage and
bone thermal necrosis

 The AO fixators consist of systems in four
sizes, depending on the size of the rod :
 Large : 11 mm tubes/rods + Schanz screws
from 4 - 6 mm
 Medium : 8 mm tubes/rods + Schanz screws
from 3 - 6 mm
 Small : 4 mm tubes/rods + Schanz screws
from 1.8 - 4 mm
 Mini : 2 mm system for fingers; it is presently
available in the conventional design and
includes multi pin clamps for K-wires and 2
mm longitudinal rods
 Stainless steel, aluminum alloy, carbon fiberAO Principles of Fracture Management. 2000

 - Simple (ie, single) clamps
connect one pin to a rod
 - Modular (ie, universal) clamps
allow multiple pins to be
connected to a rod
 - Distributing the pins
symmetrically within the clamp
provides the best pin fixation
strength within the clamp.

 Ring fixators  useful in fractures around the
joint and in those with significant bone loss.
 allow for dynamic axial loading (ie, weight bearing)
and joint motion during treatment.
 Hybrid frame  combines the advantages of
ring fixators in the periarticular region and the
simplicity of planar half-pins in the diaphyseal
region.

 Bilateral (ie, placed on both sides of the bone)VS Unilateral
 stiffer,
 can be cumbersome to apply
 hold a higher potential for pin infection
 UniplanarVS multiplanar.
 less obstructive for soft tissue access but are 4-7 times weaker
 Pins and bars should be aligned with the bending axis of the bone.
 Ring fixator is used for oblique fractures, placing angled pins
parallel to the fracture line to create a structural parallelogram is
more effective at reducing shear than is the use of transverse pins.

1. Distance of pins/Schanz screws
 From the fracture line :The closer the better (x)
 Within each main fragment, the further apart the
better (y)
2. Distance of longitudinal connecting tube/ bar from
bone :The closer the better (z)
3. Number of bars/tubes: two are better than one
4. Configuration (low to high stiffness): Unilateral/V-
shaped/bilateral or triangular frame
5. Combination of limited internal fixation (lag screw)
with external fixation

 Insufficiently stable external fixation may
delay fracture healing and lead to pin loosening.
 Too much stiffness or rigidity of the external
fixator construct may also delay fracture
healing, especially in open fractures.
 In the management of such fractures it may be
necessary to “dynamize” an initially quite stable
configuration or add stability in case of pin
loosening

 Pin fixators :
 Unilateral
 V-shaped
 Bilateral frame
 Triangular
 Ring (wire fixators)
 Hybrid fixators (wire and pin)
 Pinless external fixator
 Mefisto

 First generation frames classic A frame
 Subsequent frame generations created
to improve upon shortcomings
Lambotte’s original frame 1902
Rockwood and Green, 6th ed p. 258

 Subject to cantilever bending
 Biplanar with improved biomechanical
properties
Bilateral uniplanar
unilateral biplanar

 Ilizarov
 Superior biomechanically and
implemented with improved results for
definitive care.
 Allows axial micromotion
 Stable to angulation and rotation
 Good peri-articular fixation

 Allow for joint range of motion
 Modified unilateral frame
 Tried to incorporate the benefits and
versatility of circular fixation with the ease
of unilateral fixator design.
 In essence, added moving parts to 2nd
generation designs.
 Ignored basic biomechanical constraints.
 Did not alter issues of bending, shear, and
torque.

 Taylor spatial frame (TSF)
 6 degrees of freedom (6 struts in multi-planar configuration)
 Deformity correction
 Computer software to facilitate correction

 Improved ease of use
 Mates the advantage of metaphyseal fixation with
ease of use of half pins
 Not biomechanically superior to full ring
 Combines the advantages of ring in periarticular
areas with simplicity of planar half pins in
diaphysis
 Disadvantage of increased sheer secondary to half
pin use vs full circular ring frame
 Main advantage is for convenience

 A construct used in fractures close to a joint  called
“hybrid” because it combines wire fixation (3/4 ring
fixator) with pin fixation (unilateral fixator in the
diaphysis).
 It requires K-wires for the halfring and conventional
Schanz screws for the shaft.
 There are K-wires with an olive which allows for
fragment adaptation by applying some compression
 Mainly used in typeA and B fractures of the proximal
and distal tibia, either free-standing or to protect a lag
screw internal fixation
 It is not easy to insert a hybrid fixator correctly in an
articular fracture, nor is it a quick procedure
 It may therefore be done as a second step in
polytraumatized patients or open fractures after initial
joint-bridging fixation
AO Principles of Fracture Management

 Advantages :
1. Minimally invasive alignment of simple articular fractures
2. Better anchorage of thin wires than of conventional pins in
cancellous bone
3. Free postoperative joint motion
4. Can be combined with lag screws
 Disadvantages :
1. Risk of articular infection. The proximity of K-wire pin tracks to a
joint may be hazardous
2. Radiopaque ring may obstruct x-ray assessment of the reduction
in standard x-ray views

 Main goal : to avoid penetration of the medullary
canal  reducing the risk of deep infection in case of
secondary intramedullary nailing
 The sharp points of the forceps-like fixator applied to
the bone by a rocking motion and only penetrate the
cortex superficially
 Forceps of varying sizes and shapes are available to
adapt to the triangular cross-section of the tibia at
different levels
 Once the forceps are well anchored in the bone, the
fracture is reduced and the four forceps are
connected by a simple bar or as a tube-to-tube
arrangement

 A recently introduced
external fixator
 Mainly for limb lengthening
and bone transport
 Modular configuration 
very useful tool for the
management of fractures

 Pin InsertionTechnique
 To avoid tendon penetration or injuries to nerves,
vessels, and muscles  must be familiar with the
anatomy of the different cross-sections and make
use of the recommended pin placement sites

 Diaphyses
 Avoid heat damage to the bone when inserting a pin or Schanz screw
into hard cortices
 The sharper the drill bits or screws, the less heat is generated
 The temperature rises as insertion speed increases
 Burning the bone  early loosening due to ring sequestrum formation
 A correctly inserted pin or screw should catch the opposite cortex but
not protrude too far past it. Correct depth insertion may be achieved
by feeling the opposite cortex (probably the best way), using
measuring gauges (fairly difficult), or by intraoperative x-ray (which
may be misleading)
 To avoid heat damage, the holes for Schanz screws and Steinmann
pins must be predrilled

 Metaphyses
 Bone heat generation is not such a problem
 The use of self-drilling screws may be safer
 Joint involvement must avoided because of the danger of pin-track
infection which could progress into the joint
 When inserting a pin or Schanz screw it is important :
▪ not to injure nerves or vessels,
▪ not to place them into the joint,
▪ to avoid the fracture line,
▪ not to “burn” the bone,
▪ to insert a screw of the correct length,
▪ to use self-drilling screws in metaphyseal bone.

 It is not necessary to place the Schanz screws at anterior tibial
crest in unilateral application
 The drilling of a hole in thick tibial crest  associated with excessive
heat generation  necrosis of the bone
 Insertion of a Schanz screw at the tibial crest may be difficult as the tip
of the drill bit may slip medially or laterally damaging the soft tissues
 In the distal tibia :
 Risk of damage to the tendons tibialis anterior and extensor digitorum
muscles and the most distal pin sites  highest infection rate
 Safe zone on the anteromedial aspect of the tibia  Schanz screws
can remain for a long period without infection

 Soft-tissue management is critical
 Should entail choosing an anatomic site without a large soft-tissue
sleeve
 making an adequate skin incision,
 spreading tissues to bone,
 Using cannulation during drill/pin insertion with the use of
protective sleeves,
 stabilizing soft tissues around the pin to prevent motion
 excessive motion of muscle and skin around bone  local
inflammation pintract infections. (use gentle compressive
dressing around the pin)
External Fixation: Principles andApplications. JAAOS. Nov 2015,Vol 23, No 11

 Thermal damage (osteocyte death and alkaline
phosphatase inactivation, are seen at 122F (50C)
 predrilling,
 irrigation during drilling, and
 power insertion of the pin
 Visible “wobble factor” when predrilled pins were inserted
by hand.  leads to conical deformation and subsequent
instability of the near cortex, causing increased stress in
the far cortex

 Most external fixators placed in the United
States today are for provisional stabilization
 simple constructs
 with consideration of their impact on the
patient’s physiology and care, any future
definitive fixation, and implant cost
 Within the pediatric population, care must be
taken to avoid the epiphysis and open physis.

 Pins (5 mm) are placed anterolaterally in the
proximal humerus,
 avoid damage to the axillary and radial nerves,
and
 Posterolaterally (4 to 5 mm) in the distal
humerus,
 avoiding the olecranon fossa

 “Floating elbows” can be stabilized with
 posterolateral distal humerus pins (4 to 5 mm)
 subcutaneous proximal ulna pins (4 mm).
 A hinged fixator can be used for definitive
treatment of certain periarticular fractures or
ligament instability

 Ulna is best used for forearm stabilization
 Pins 4 mm & 3 mm are subcutaneously placed
proximally and distally
 Proximal radius pin placement should be
avoided because of the variable location of the
posterior interosseous nerve.
 The superficial radial nerve is at risk during distal
radius pin insertion

 The proximal pins (3 to 4 mm)
 placed posterior to the radial artery
 protected the superficial radial nerve
 Distal pins (3mm)
 into the base of the second metacarpal using a small incision
 identify the terminal branches of the superficial radial nerve
 sharply elevate off the first dorsal interosseous muscle
 Overdistraction of the wrist joint should be avoided
 can cause difficulty with finger flexion
 Complex regional pain syndrome

 anteriorly placed fixator can be used to close an APC
injury, open a LC injury, or translate a vertical injury
 2 cm posterior to the anterior-superior iliac spine is
carried down to bone to avoid injury to the lateral
femoral cutaneous nerve
 Pins are directed posteromedially between the inner
and outer tables of the gluteal pillar.
 If needed, a second pin on each side can be placed
more posterior on the crest and angled more
horizontally.

supra-acetabular pin supra-acetabular pin
orthogonal pin construct (both iliac
crest and supra-acetabular pins) subcristal pin

 Posterior pelvic external fixation
 pelvic C-clamps applied to the posterior ilium above the
greater sciatic notch
 Complications related to errant pin placement if done
without fluoroscopy
 alternative : pelvic C-clamp pins is placed into the
greater trochanters so that the C-clamp acts in the
same fashion as a pelvic binder or sheet, and the pins
can be placed relatively safely

 pins (5 mm) placed anterolaterally or directly
lateral, both proximally and distally
 distal pins must be placed with consideration
to avoid the suprapatellar pouch

 Knee dislocations, distal femur fractures, and
tibial plateau fractures
 using pins (5 mm) in the anterolateral femur
and the anteromedial tibia
 Proximal tibia pins should be placed at least 14
mm distal to the articular surface to avoid joint
penetration
 fixator should be locked into a slight amount
of flexion, (5 to 15*)
 posterior splint may be used –> additional
stability

 The subcutaneous anteromedial surface of
the tibia
 perpendicular to either the anteromedial or
posterior faces of the tibial cortex
 Distal pins should be placed using blunt
dissection to avoid injury to the anterior tibial
vessels and the deep peroneal nerve

 Delta frame
 anteromedially placed
tibial shaft pins
 transfixation pin, into
the calcaneus aids in
fracture reduction and
stabilization

 The safest medial
calcaneus placement is
Posterior to the halfway
point from the
posteroinferior calcaneus
to the inferior medial
malleolus and
 Posterior to the one-
third mark from the
posteroinferior calcaneus
to the navicular
tuberosity

 Alternatively, additional pins may be placed
 medially into the talar neck cuneiforms, or first
metatarsal base,
 or laterally into the cuboid or fifth metatarsal base

 Half-pins (5 mm) are placed medial to lateral
in the distal tibia, medial cuneiform, and
calcaneal tuberosity.
 After bar placement, a laminar spreader
and/or compressor distractor device is used
to strategically reestablish length as well as
correct the varus and translation deformity.

 condition of the soft tissues,
 the initial injury,
 The need for further surgical débridement,
 fasciotomy wounds,
 The condition of external fixator pins,
 external fixator stability,
 bone or soft-tissue loss,
 vascular injury,
 infection,
 the physiologic state of the patient

 most frequently is performed as a single procedure,
 a staged conversion, or “pin holiday,” before definitive
fixation is sometimes warranted.The most notable
circumstance is concern for pin-site infection.
 removing the fixator,
 débriding the pin sites,
 Placing the extremity in a splint or traction,
 and administering antibiotics before returning to the
operating room fordefinitive IMN.

 can be a successful strategy in the acute
management of difficult periarticular
fractures

 37.5% with virulent Staphylococcus aureus
9.4% with Escherichia coli
 Significant correlation between loose pins
and infection,

 Depending on what is easier and on local priorities
 The fixator is applied after reduction (reduction first) or
the fixator is used as a reduction tool (fixator first) 
modular frame construction is required
 A pair of pins is inserted into each main fragment and
joined by a short tube or rod
 The two tubes or rods are then connected by a short
third tube and two special tube-to-tube clamps
 This construct allows the surgeon to manipulate and
reduce the fracture and to hold it after reduction

 Advantages :
Free pin placement allowing the surgeon :
 to spread both pins, increasing frame stiffness
 to position pins according to the fracture pattern or soft-
tissue injury
 to avoid injury to nerves or vessels
 The application of the external fixator “first” 
reduced x-ray time
 Tube-to-tube clamps have a better grip on stainless
steel tubes than on carbon fiber rods

1. Pin-track care
 Starts with correct pin insertion
 Daily cleansing and desinfection with Betadine paste is recommended
 In case of persistant pin-track infection the pin has usually lost its firm hold in
the bone
 On x-ray a seam of bone resorption can be observed and mechanically the pin
appears “loose”  only change of the pin to a new site can solve the problem
2. Change to internal fixation
 The bulk of the device, its discomfort, the need for daily pin care, and the possible limitation of joint
movement
 The patient’s wish to change to an internal stabilization

 With a few exceptions (bridging, emergencies,
tensioning), external fixator constructs can be
partially loaded from the very beginning
 As healing progresses, the load is increased until
full weight bearing is achieved
 Partial and full weight bearing under external
fixation is the best and most effective method of
dynamization

 Three basic treatment choices :
1. Definitive treatment with the external fixator until solid
bone healing
2. Early conversion to internal fixation, especially
intramedullary nailing, within 2–3 weeks
3. Conversion to nonoperative treatment, eg, plaster,
orthosis, caliper, etc
 In cases of poor skin coverage or critical soft-tissue
concerns  ORIF  a high risk of infection. External
fixator may be retained as the definitive treatment

 If the change to intramedullary nailing is decided later
than 2 weeks or in case of pin-site infection
 It is advisable to remove the external fixator, curette the
pin tracks, and place the limb in a plaster cast until all signs
of infection are gone
 An alternative may be to replace the standard external
fixator by a pinless device
 Where plating is planned, the fixator may be kept a week
or two longer prior to change; however, here too the pin
tracks should be clean

 Arthrodesis
 First applications for ankle fusion  applying compression bilateral frame. Also used for knee
and elbow fusion, especially in infection
 Infection
 Ultimate way of stabilizing an infected fracture or non-union, the pins can be inserted away
from infected focus
 Limb lengthening / bone transport - distraction osteogenesis
 Introduced by Ilizarov with ring fixator
 Can also be applied using tubular external fixator and Mefisto, with the limitation: angular
and rotational corrections cannot be performed simultaneously
 Corrective osteotomies
 In cases of poor or compromised soft-tissue cover, ie, when internal fixation would be
associated with high risk.The other indication is for osteotomies combined with bone
transport.

(OBQ11-7) Which of the following techniques increases
strength and stability to an external fixation construct?
1. Unicortical pin fixation
2. Decreasing total pin separation distance
3. Increased working distance from the pin to fracture site
4. Decreasing the distance between the bone and the
construct
5. Using smaller diameter pins

 PREFERRED RESPONSE ▼ 4
 DISCUSSION:There are several methods that can be used to increase the
strength of an external fixation construct. Decreasing the distance from the bar
to the bone increases stability and strengthens the construct. Some other
methods to increase stability include: good bone-to-bone fracture end
apposition, using an increased number of pins, using larger pins, small distance
from the near pins to the fracture site (smaller working distance), increased
spacing between the near and far pins, and bicortical pin fixation.
Tencer et al looked at biomechanical aspects of external fixation systems.They
demonstrated that system rigidity could be increased by maximizing pin
separation distance in the fracture component and the number of pins used while
minimizing pin separation distance across the fracture site and the sidebar offset
distance from bone.
Incorrect Answers: Answer choices 1,2,3, and 5 all act to decrease external
fixation construct strength.

(OBQ10-226) A locked plate used in a bridge plate
fashion is biomechanically most similar to which of
the following fixation methods?
1. Lag screw
2. Lag screw plus non-locked neutralization plate
3. External fixator without compression
4. Lag screw plus locked neutralization plate
5. External fixator used in compression mode

 DISCUSSION:The definition of a bridge plate is one where (1)
there is no direct compression between the bone ends at the
fracture site and (2) the screws are placed far from the fracture site
(thus increasing the working length of the construct). Keeping the
screws remote from the fracture site prevents disturbance of the
blood supply and allows more motion of the construct.This is ideal
for spanning comminuted segments, not for simple fracture
patterns. A bridge plate with locking screws functions the same as
an external fixator, except that it is placed internally. Like plates,
external fixators can be designed to compress across a fracture or
osteotomy site.

(OBQ09-177) Which of the following Figures shows
a fixation construct achieving absolute stability?
1. FigureA
2. Figure B
3. Figure C
4. Figure D
5. Figure E

 DISCUSSION: FigureA shows percutaneous pinning, Figure B shows locked
bridge plating, Figure C shows intramedullary nailing, Figure D shows lag fixation
and neutralization plating, and Figure E shows external fixation. All except Figure
D show relative stability constructs.
Absolute stability is a construct seen in Figure D, where lag screws and a
neutralization plate are shown in a postoperative clavicle. No micromotion is
seen with this technique, and healing is by primary (Haversian) healing, as
opposed to the other four constructs, which have relative stability and heal via
callus formation.The first reference, the AO Principles textbook, covers this in
depth.The second reference by Claes et al notes that bone can still heal with
bone (as opposed to fibrous union) with strain rates up to 15%.

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