External fixators are devices used to stabilize fractures located outside the body. They minimize metal inside tissues and allow for easy wound access. Pin fixators use cantilevered pins for stabilization while ring fixators form an exoskeleton around the limb for deformity correction. Proper pin placement and preloading are important for stability at the pin-bone interface. Dynamization through loosening of the fixator over time stimulates healing. External fixators are indicated for open fractures, bone defects, and limb lengthening and have advantages of being minimally invasive.

1. External Fixator
DR DITESH JAIN
DEPT. OF ORTHOPAEDICS
LILAVATI HOSPITAL MMUMBAI

2. Definition:
 External fixator is a device used to stabilise and immobilise
fracture`s(mostly long bones); where device is placed outside of the body.
 In external fixation minimum metal exist inside the tissue.
 Wound is well exposed, local lavage, flushing, dressing can be done.
 Surgical procedure is easy, convenient and cause minimal discomfort to
the patient (DCO).

3. Classification:
 External fixators can be broadly divided in two types:
1. Pin fixators
2. Ring fixators

4. Pin Fixator

5. Pin Fixators:
1. Adv:- Excellent for routine work, applied
quickly with good wound access.
2. Disadv:- Fracture need to be reduced
before application, limited adjustability in
controlling angular and rotational
deformity.
3. Pin fixator works on cantilevered
mechanism; therefore does not allowed
axial loading.
4. Not suitable for progressive deformity
correction.
5. High incidence of delayed or non-union,
angular deformity may occure.

6. Components of Pin Fixator:
 Pins
 Half pin or Shanz Pin:
1. Stabilising hold on bone segment.
2. Available in 3-6mm.
3. Modified cortical screw (3.4 for 4.5mm; good torsional and bending
strength) with thread at one end and round tip at other with no head and
long shaft.

7.  Steinman Pin:
1. Fritz Steinmann (1870–1933), a surgeon in Bern, Switzerland, introduced pins for
skeletal traction in 1908.
2. Steinmann pins are made in diameters from 3 to 6 mm and in lengths from 150 to
300 mm. The pointed end is usually of the trocar or diamond point.
3. The shaft of the Steinmann pin is smooth or threaded.
4. Steinmann pins that are partly threaded in the central section are easy to introduce
and are as effective as fully threaded Steinmann pins. As the thread diameter is 0.5
mm larger than the pin

8.  Clamps: Connection between
pin and other parts of the
fixator.

9.  Couplings: connect rod or tube with other
rods and tubes or pins.

10.  Central Body:
1. The central body, a connecting rod, or a tube is the main structure of the
fixator.
2. Stainless steel, Titanium, Plastics and Carbon fibre-reinforced resin.
3. Modular systems employ rods or tubes and a variety of tube-to-tube
articulations that interconnect the pins or pin groups

11. • Compression – Distraction System:
 Assembly can be fixed to main structure and used to apply compression or
distraction at the site.

12. Required Instruments:

13. Fixator Frame
 Three dimensional structure built with components of fixator system is
called fixator frame.
 External fixation frames — classification
1. Type 1 Unilateral
 1A Unilateral uniplanar
 1B Unilateral biplanar
3. Type 3 Modular
2. Type 2 Bilateral
 2A Bilateral uniplanar
 2B Bilateral biplanar (3D)

14. Type 1: Unilateral- Easy to use
 1A: Uni-planar  1B: Bi-planar

15. Type 2: Bi-Lateral- Better Fixation and
rigidity.
 2B: Uni-planar
 2B: Bi-planar

16. Type 3: Modular frame- Greater degree of
freedom
1. Modified unilateral uniplanar frame.
2. Total pin placement freedom.
3. Easy dynamization.
4. Quick pin addition or removal.
5. Applicable in segmental fracture and
joint injuries.
6. Stable for bone segment
transportation.

17. Mechanical Properties of Pin Fixators
 External fixator stiffness increases with an increase in:
1. Pin number and diameter
2. Pin separation distance in a bone segment
3. Pin insertion angle: Torsional Stress
4. Rod number and diameter.
 External fixator stiffness decreases with an increase in:
1. Pin separation distance across the fracture: Increase bending stress; Inc Cantilever
Moment arm
2. Rod-bone distance. Inversely Proportional to stability

18. Interfaces Along the External Fixator
A. Pin Clamp interface:
 Slippage at this interface is the most common cause of loss of frame
stiffness.
 Prevented by regular tightening of pin clamps.

19. B. Pin Bone interface:
1. It is the Achilles of any external fixator.
2. It’s the race between healing bone`s load carrying capacity or failing pin-bone
interface.
3. Factors to decrease stress at pin bone interface:
a. Large pin diameter: more moment of inertia.
b. High modulus of material.
c. Reduced pin span.

20. a. Pin cluster at critical fixation points.
b. Fixator applied in two plane.
c. Good hygiene prevent pin tract infection i.e. loosening is less.
d. Reduced weight bearing.
e. Proper pin insertion technique.(Eccentric, thermal necrosis etc.)
f. Pre-loading.
g. Distance between pin clam and pin bone interface is ideally 4cm.
h. Optimal pin pilot hole mismatch should be less than 0.1mm.

21. Pre-loading:
 Preload is a static force of sufficient magnitude applied to an implant to
overcome all dynamic and muscular contraction forces and to maintain
uninterrupted pin–bone contact.
 Lack of tension at the pin-bone interface leads to micro-motion, which in
turn induces loosening of the pin in the bone.
 If pin loosening is to be avoided, the pin must abut firmly against the
cortex.
 A bending preload, or preload along the long axis of the bone has
limited effectiveness because it stabilizes only one of the interfaces.
 The best method to preload the interface is a radial press fit. This is
achieved by inserting a pin which is larger in diameter than the pre-drilled
hole—a designed misfit.

23. Ring Fixator

24. Ring Fixators
 These are external fixator with complex construction which some what looks like
exoskeleton.
 Deformity correction can be done in multiple planes.
 Fracture healing better than pin fixators.
 Disadv: heavy, cumbersome and time consuming with more chances of
neurovascular injury.

25. Components of a Ring Fixator
 Components are divided in two types:
1. Main Parts: used to make thee main exo-skeleton.
 Rings
 Wires
 Wire Fixation Bolts and buckels
 Pin and pin Clamps
2. Secondary Components: components necessary for for assembly of
fixator.
 Rods
 Plates
 Post hinges
 Washer
 Sockets
 Bushing
 Bolts and Nuts

26. Rings:
 Principle components with flat surface and multiple holes.
 Always aligned perpendicular to the long axis.
 They can be of steel or carbon fibre.
 Can bear the stress up to 150kg.
 Types of Rings:
1. Full ring
2. Half ring: 18 to 28 holes @ 4mm apart of 8mm size
3. 5/8th ring
4. Clover ring
5. Half ring with curved ends.

27. Ring Coonnections:
 Bolts and Nuts: Pitch of 1mm

28. Ring Connectors:
7 types of connectors are used to connect rings:-
1. Rod: 6mm steel rod, 4 rods at equidistant.
2. Slotted Rods: 2x2mm slot for 20 threads. Connects rings and pulling
device.
3. Telescopic Rods: partly threaded rods stiffer than threaded rods.
Graduated telescopic rods are more superior device for controlled
distraction and compression.

29. • Connection Plates: Reinforce ring
and used to make oval rings.
Plane
With bolt
attachedTwisted
Curved
With
threaded
slots

30. 1. Threaded Sockets:
improve stability.
2. Post and Hinges:
3. Wire Fixation Bolts:
Cannulated/Slotted:
2mm hole, 10x14mm
oval head
4. Washer: 7mm hole, fills
space and provide lock
tight fastening.
Slotted/plane, 1.5mm to
4mm
5. Wrenches

31. Frame Assemblage:
 Two prevalent methods:
1. Construction Before Surgery.
2. Assembly during Surgery.
 Rings are placed perpendicular to long axis with only 10 deg. of error allowed.
 Space between Ring and skin: At least 3cm optimal.
 Methods to calculate ring size:
1. Circumference/3+6cm = ring diameter. [circumference at maximum girth]
2. Anticipate and look for size by size.
3. Using plastic templates.

32. Types of Rings: Majorly 4 types of rings:-
3-5 cm from joint
3-5 cm from site
At point of maximum
deformity/change of
forces.

33. Ring Orientation

34. Wires In Ring Fixators:
 Kirshner Wire: M/c used, its elastic but stiffened on tensioning but retains
small degree of elasticity which allows micro-motion; good for callus
formation.
 Size: Adult-1.8mm, Child-
1.5mm
 Cortical: Bayonet tip
 Cancellous: Trocar Point
Tip
 Inserted at least 3 cm
apart
Byonet Tip
Trochar Tip
Olive wire With
Stopper.

35.  Wire Positioning: Two Wire Criss-crossing at 90 deg.
 Olive Wire: Wire with Stopper used to prevent side to side movements and to induce
sideways re-location of bone fragment. When used with offset wire prevent shearing of
the ring.
Offset Wires
Olive Wires

36. Wire Tensioning:
 Only a wire under tension can
sustain large loading forces.
 Degree of tensioning depends
on following factors:
1. Local frame construct
2. Local bone condition
3. Patient`s weight
4. Functional wire loading
(Distraction and compression)

37.  Methods of wire Tensioning:
1. Nut and Bolt Simultaneously with wrench.
2. Wire Tensioner.
 Method to measure wire tension:
1. Dynamometric wire tensioner.
2. Practical guide, when stuck with a metal, a
well-tensioned wire produces a high-pitched
note; a loose wire emits a dull tone.
 Wires tend to slacken over a period. Loose
wires cause pain and inflammation of the
surrounding tissue.
 Re-tensioning is performed by applying two
wrenches simultaneously to the head of a
fixation bolt and nut and slowly turning both of
them a quarter or a half turn.

38.  Guide Wires:
1. Used to maintain desirable direction of
fragments.
2. Wire is drilled and buried in proximal
bone.
3. Its never tensioned.
 Pulling or Traction Wire: Introduced
before the corticotomy. The distal end
of the traction wire is connected to the
traction device. Wire is removed in
retrograde direction.
 Methods of traction:
1. Olive Stopper
2. Z – shaped Wire Twist
3. Hooked End

39.  Ring Fixator and Schanz Screw:
1. Used when trans-osseous wire likely to
damage neuro-vascular bundle.
2. Additional Hold in presence of wire
fixation.
3. Connected to ring by threaded socket.
 Hinges:
1. Gives capability of secure and established
angulation.
2. Used as pivot necessary for correction.
3. Guides motion in desired plane.
4. Act as a fulcrum for control angulation
and displacement.
5. Offer pivot for biological adaptation of
tissue to new position.

40. General Features

41. Fracture healing by External fixator:
 In fractures treated by external skeletal fixation healing progresses by
secondary (indirect) methods.
 Accurate reduction that will allow healing of the primary type is infrequent
except under rigorously controlled experimental conditions.

42. Effect of fracture type on its healing in
external fixation
 In a transverse or short oblique fracture
all displacement takes place at one
fracture gap. Instability of the fixation
leads to a high strain situation in the only
fracture plane inhibiting fracture healing.
 Therefore, a high stability of fixation is
required for fracture healing.
 In a comminuted fracture the
displacement is shared between several
fracture gaps and low strain situation
persists. Less rigid fixation is adequate.

43. Rigid versus dynamic compression
under external fixation
 Fracture site is mechanically stimulated when the rigidity is altered to allow
relative displacement of bone ends.
 Methods of stimulation:
1. Static axial loading during weight bearing only. Contact lost when
weight is taken off.
2. Dynamic stimulation is done by clamp adjustment where only axial
movements is allowed and bone contact is maintained always.
3. A computer-controlled actuator regulates the axial displacement. This is
achieved either by load control or by displacement of the bone ends, and
weight bearing is not required.

44. Dynamization
 The term ‘dynamization’ embraces both the application of micro-movement
and of loading to the fracture site without angulation, rotation or distraction
of the fragments.
 Following Methods:
1. The use of an elastic frame with overall low rigidity.
2. Progressive dismantling of the frame.
3. Increased weight bearing in a low-axial-stiffness frame.
4. Bio-compression. Weight bearing controls the axial strain on the fracture and
it is believed that the patient’s natural feedback mechanism ensures the most
appropriate strain for healing.
5. Easiest ways to ‘dynamize’ the fixation as healing progresses is to loosen the
pin clamps and slide them away from the skin, providing a longer pin span.

45. Bone grafting in external fixation
 Bone grafting in external fixation is used in two ways:
1. To accelerate fracture healing in the early stages of consolidation.
2. As an additional procedure in a delayed or arrested healing process.

46. Good pin insertion practice
1. Inserted to construct a stable frame with maximal access to the injured soft
tissues.
2. Minimal distance between two single pins should be 3.5 cm.
3. The pins should be pre-stressed (preloaded) in each fragment.
4. Make a liberal skin incision; spread deeper soft tissues with haemostat.
5. Lift periosteum with small elevator to prevent damage by drill bit.
6. Use trocar to mark pin insertion point.
7. Employ sleeve to drill a pilot hole and to insert a pin.
8. Use a power drill.
9. Sharp drill bit with Simultaneous saline irrigation prevents thermal damage.
10. Often clean drill bit flutes.
11. Use depth gauge for accurate pin length.
12. Insert pin with hand instrument.

47. Infection and pin loosening
 Limb segments are classified into two groups:
1. Concentric segment: bone is surrounded by
muscle mass on all sides the femur, the humerus,
the radius and proximal phalanges.
 The movements between the pin shaft and the soft
tissues predispose to a high incidence of pin tract
infection, fibrosis of muscles, and joint stiffness.
Neurovascular complications are frequent.
2. Eccentric limb segment: one border or surface of
the bone is subcutaneous. The ulna, the tibia,
metacarpals, metatarsals and the pelvis.
 The pin travels through a minimum thickness of the
soft tissues so infection and other complication are
minimal.

49. Indication For Ex Fix:
1. Long bone fractures
2. Open fractures
3. Comminuted fractures that cannot be anatomically reconstructed
4. Osteomyelitis
5. High-energy fractures with soft- tissue injuries and vascular compromise
6. Trans articular ESF in arthrodesis
7. Temporary splintage during healing of soft tissue or osseous structures
8. Non-union / with bone graft

50. 9. Corrective osteotomy for antebrachial /tibial growth deformities
10. Limb lengthening procedures
11. Conjunction with internal fixation in humeral, femoral or tibial fractures
12. Hybrid ESF system- humeral, radial or tibial fractures with very short distal
or proximal fragment
13. Mandibular or maxillary fractures- usually with acrylic fixators
14. Lubosacral fractures & luxations
15. Avian limb fractures
16. Fracture repair in small exotic mammals

51. Advantage of Ex Fix
1. Minimally invasive method, preserving blood supply & soft tissues
2. No implants at the fracture site
3. Possible closed application which limits iatrogenic trauma
4. Provides immediate wt. bearing after surgery
5. Maintains normal joint mobility
6. Provides optimum environment for osteo-synthesis & wound healing
7. compatibility with internal fixation devices
8. Technical ease of application and removal
9. wound management in open fractures

52. Disadvantages
1. Device must be cleaned and monitored regularly
2. Care to prevent additional damage to device
3. Aftercare is more labour intensive
4. More rigid type II and III frames cannot be used for fractures of femur &
humerus
5. Difficult to apply and more pain in areas of increased muscle mass

53. Complications:
1. Pin tract infection
2. Focal osteomyelitis
3. Ring sequestrum
4. Premature pin loosening
5. Instability at the fracture site
6. Pin breaking
7. Pin tract osteolysis
8. Pressure necrosis of skin
9. Iatrogenic bone fracture

54. Regional Consideration

55. Sites of Application:
1. Open fracture Tibia and Fibula
2. Open fracture Femur
3. Floating Knee
4. Open Fracture Humerus
5. Communited fracture distal Radius
6. Pelvic fracture.
7. Hand & Foraarm complicated fracture.

56. The Tibia
 Most Common bone treated with external
fixator.
 Modular version are versatile in its stabilising.
 Pins are placed according to soft tissue
condition.

57. Polytrauma Patient
 Early bone fixation is very important in improving the vital prognosis of the
polytraumatized patient.
 When internal fixation is not practical because of the long operating time
and inadequacy of postoperative intensive care, external fixation may be
carried out swiftly and effectively.
 DCO

58. EXTERNAL FIXATION IN CHILDREN

60. Summary
 External fixator not a ‘First and final’ (PDFC) technique in fracture treatment
 Excellent short-term stabilizer in open wound, poor soft tissue condition and
infection
 Replaced by definitive implant when situation improves
 Concentric limb segments poorly tolerate fixator pins: early removal
recommended
 Eccentric limb segments fairly tolerate fixator pins: potentialfor long term
retention
 Modular frames are practical and preferred
 Pin-bone interface is the weak link: deterrent for long term application
 Major role in developing countries with limited resourses.
 Best modality in scenarios of war and natural disasters.