This document provides information on various external coaptation and internal fixation techniques. It discusses indications for external coaptation including casts, splints, and bandages. It then covers various internal fixation techniques like K-wires, cerclage wiring, intramedullary pinning, bone plates, and dynamic compression plating. Key principles and steps for various techniques are outlined along with their advantages and limitations.

1. PRESENTATION
ON
EXTERNAL COAPATION TECHNIQUES
&
INTERNAL FIXATION TECHNIQUES
Dr. NAVEEN KUMAR VERMA
VET. SURGEON

2.  EXTERNAL COAPATION:- External coaptation may be used
to provide patient comfort before surgery and decrease soft tissue
damage, It also may be used as the primary repair in some
conditions. Casts, splints and bandage.
 INDICATIONS :-
 Closed fracture below elbow or stifle.
 Fractures amenable to closed reduction.
 Fractures in which the bone will be stable after reduction relative
to shortening or distraction.

3. Fractures in which the bone can be expected to heal quickly enough
that the cast/splint will not cause severe joint stiffness and muscle
atrophy (fracture disease).
 Specific indications follow:
 Greenstick fractures.
 Long-bone fractures in young animals in whom the periosteal
sleeve is mostly intact.
 Impaction fractures.

4.  Casts is used for providing immobilization,
especially after surgery.
 Casts immobilize the joint above and the
joint below the area that is to be kept straight
and without motion
 Growing animal- every 2 weeks, adult- 4 to 6
weeks
 TYPES
 Plaster - white in color.
 Fiberglass - comes in a variety of colors,
patterns, and designs

5.  Step wise procedure for applying cast:
 Strips of adhesive tapes are placed on the cranial and caudal
surface of foot and allowed to protrude several inches distal to
end.
 An orthopedic stockinette is applied to the limb with extra length
at top and bottom.
 Cotton padding is applied to the limb starting from toe to
upward.
 Wetted plaster of paris is rolled on to the limb from disital to
proximal portion and then return distally.
 After hardening stockinette and tape on the digital end are
reflected proximally and fixed with single strip of plaster splint.
 A final row of plaster may be applied and smoothed in place

7.  INDICATIONS:
 The Schroeder-Thomas splint can be used to immobilize any
fracture distal to the midfemur or midhumerus.
 It is also a useful device for immobilization of joints distal to
the elbow (including elbow joint) in fore limb.
 Schroeder-Thomas splint can be useful in immobilizing
distal femoral or tibial fractures in hind limb.
 CONSTRUCTION:
 The frame of the splint is made of aluminum rods should be
sufficiently stiff that it will not bend.
 The first important component to manufacture for the splint
is the upper ring, which encompasses the thigh.

8.  The ring should be constructed in a round fashion.
 Bend the ring in an approximately 45degree angle and flatten
the ring so that it will conform to the dog's body.
 The ring should cover the tuber ischii caudally and tuber
coxae proximally in case of hind limb.
 Bending of lower ring should be in the contour of limb
otherwise it may act as a fulcrum to create other
complication.
 Tape is usually applied to the ring .
 The outside of the aluminum frame is covered with adhesive
tape
IN LARGE ANIMALS
 Methods of application is almost similar to that of small
animal.
 Mostly made up of G.I wire-5mm to 15 mm

10. A Robert jones bandage is frequently reinforced with rigid
materials like aluminium splint rods to enhance immobilisation of
joints.
Advantage-Large bulk and weight of conventional bandage is
avoided.
Precautions
 Strips of tape must never be applied in a circumferential
manner because it may obstruct vascular supply.
 Cotton padding should begin from toes and then gradually
wrapped around the limb and continued proximally upto the
level of the mid shaft femur or humerus.
 The nails of two middle toes should remain barely visible to
access post bandaging vascular blood supply.
 Too much of excessive tension should not be applied while

11. EHMER SLING
 INDICATIONS
To provide stability following reduction of a
cranial and dorsal dislocation of the hip
joint.
PURPOSE
 To provide abduction and internal rotation of the
femur and flexion of the knee, places the
femoral head into a position with in the
acetabulam.
 The Ehmer sling is not useful with ventral
dislocation of the hip, since abduction of the leg
would be contraindicated and may cause
relaxation.

12. VELPEAU SLING
 The Velpeau sling is a shoulder bandage that will relieve the
forelimb of weight bearing. It keeps the carpus, elbow, and
shoulder joints in a flexed position.
INDICATIONS:
 Immobilization of scapular fractures.
 Dislocations of the shoulder joint.

13.  To promote early active pain free movement and full weight
bearing of affected limb
 Prevent fracture disease(Muscle atrophy, Joint stiffness,
Tissue adhesions, Osteoporosis)
 The Goals of fracture repair are
 Atraumatic technique
 Good reduction/alignment
 Stable fixation
 Optimize the health of joints
 Early return to full function

14.  Open reduction
 Surgical exposure of the fracture site for
fixation
 Fixation is usually internal
 Closed reduction
 Fracture site is not opened
 External fixation (casts, splints, etc.)
 Becoming more popular with advanced
imaging

15.  Earlier functional recovery
 Allows weight bearing
during healing
 Health of the limb and
joints
 More predictable fracture
alignment
 Rigid fixation usually
 No extensive care
 Potentially faster time to
healing
 Hidden implants
 Increases the circulation
 Promotes healing
• Invasive
• Prolong healing
• Costly
• Retention of
implant
• Infection

16.  Bending
 Rotation
 Compression
 Tension

17.  Relative Stability
 Absolute Stability
– IM nailing
– Ex fix
– Bridge plating
–Cast
– Lag screw/ plate
– Compression plate
Fixation Stability

18. Absolute
(Rigid)
Relative
(Flexible)
No callus
Fixation Stability
Callus
Reality

19.  Displaced intra-articular fracture
 Axial, angular, or rotational instability that cannot be
controlled by closed methods
 Open fracture
 Polytrauma
 Associated neurovascular injury
MULTIPLE REASONS EXIST
BEYOND THESE...

20.  Orthopedic wire
 Tension band wiring
 Intramedullary pinning
 Interfragmentary screws
 Plates
 Kirschner –Ehmer apparatus

21.  Flexible
 Made of stainless steel
 Usually combined with other
fixations
 Monofilament
 Different sizes

22. A. Twisting
B. Single loop
C. Double loop

23.  Tension band wiring
 Opposes tensile forces - muscle / ligament
 Converts tensile forces to compressive forces
 Indications: fixation of patella, fibular tarsal bone,
tibial tuberosity, olecranon, greater trochanter of
femur, acromian process of scapula etc.
• 2 K-wires from tip of olecranon across fx site into
anterior cortex to maintain initial reduction and anchor
for the tension wire
• Tension wire brought through a drill hole in the ulna
• Both sides of the tension wire tightened to ensure even
compression

25. Principles of full cerclage wire
 Length of the fracture line should be two to three times the
diameter of the marrow cavity
 There should be a maximum of two fracture lines (i.e., no
more than two main segments and one large butterfly
fragment)
 The fracture must be anatomically reduced
 Never use a single cerclage wire
 Place wires ~ 1 cm apart
 Place wires ~ 0.5 cm from fracture
 Kirschner wires may be used to prevent
cerclage wire slippage

26. Principles of full cerclage wire placement
 Do not entrap soft tissues
 Place perpendicular to bone
 Lock wire in place where bone changes diameter
(K-wire or notch)
 Wires must be tight
 Do not bend ends over

28.  Indications: Diaphyseal fx of humerus, femur, tibia,
metacarpal and metatarsal
 Very resistant to bending forces but do not
counteract rotational forces and Axial forces
 Require little equipment to place
 Closed or open techniques and easy to remove
 Little damage to blood supply and provide endosteal
contact
 Stacked pins
 Fill 70% of the bone marrow diameter
 IM pins alone are poorly suited for comminuted
fractures
 Combined with
 External fixator, plate, cerclage wires
 35-40% of the bone marrow cavity

30.  Steinmann pins are most commonly
used
 They vary in diameter
 Proportional to strength
 Vary in point morphology
 Chisel
 Slightly more effective in cutting
through dense cortical bone
 Trocar
 Generates more heat than chisel
 Threaded
 Increases the pin holding power to
cancellous bone.
 Premature bending or breakage

31.  Jacob’s chuck
 Low speed drill
 Normograde insertion
 Pin inserted at epiphysis and
driven across fracture line
 Retrograde insertion
 Pin inserted from fracture site
and driven through epiphysis

32. • Retro or Normograde
• Extend hip
• Inter-trochanteric fossa
• Direct laterally
• Over reduce
Tibia
• Always Normograde
• Countersink or cut short

33.  Retro or Normograde
 Exit or start distal to greater
tubercle on the lateral aspect
 Direct into medial aspect of
condyle
Radius
• Avoid IM pins in the radius
• Must go through a joint
• Oval shape doesn’t stabilize

34.  Small and elastic
 Usually used as:
 Transcortical pins (“skewer wires”)
 Pin and tension band fixation
 Cross pinning
 Dynamic pinning
 to stabilize metaphyseal and
physeal fractures in young
animals
 The pins should not cross at the
fracture site
 0.035-0.062 inch in size

35.  Specialized IM pin—but not an IM pin
 Locked in place with bone screws
 Counteracts all fracture forces
 Can be used for fractures of the femur, tibia, and
humerus
 Can be placed open or closed
Extension piece
Interlocking nail
Insertion tool
Drill guide jig: used to align the
drill bit with the holes in the nail

36.  4, 4.7, 6, 8 and 10 mm
 Various lengths
 Screw holes may be 11 or 22 mm apart
 2 proximal, 2 distal
 1 proximal, 2 distal
 2 proximal, 1 distal
 1 proximal, 1 distal
 Proximal end has internally threaded hole
and two alignment tabs
 Distal end may be trocar or blunt point

37. A few specifics
 Chose the biggest nail possible
 Don’t place an empty hole at the fracture site
 Place screws 2 cm away from fracture
 Try to use four screws total

38. Screws
• Cortical screws:
–Greater number of threads
–Threads spaced closer together
(smaller pitch)
–Outer thread diameter to core
diameter ratio is less
–Better hold in cortical bone
• Cancellous screws:
– Larger thread to core diameter ratio
–Threads are spaced farther apart
(pitch is greater)
– Lag effect with partially-threaded
screws
– Theoretically allows better fixation
in cancellous bone

39.  Available in sizes 1.5-6.5mm outer screw
diameter
 Self tapping: Has a cutting tip to cut
thread in the bone.
 Non-self tapping: requires tapping of
the bone before application of the screw
 Screw resistance to bending load is
determined by core diameter and
increases by raising the radius to the
fourth power
 Screw holding power increases with
increase in diameter of the thread

40.  Used to secure bone plates to bone
 Used as primary means of fracture repair
 Used to hold fracture fragments in place
 Used to compress fracture fragments
 Used to form prosthetic ligaments

41. POSITIONAL SCREWS LAG SCREWS
 Hold bone fragments in
place
 Do not provide compression
 Threads engage both near
and far cortex
 Place perpendicular to bone
 Used to compress fracture
fragments
 Used to hold plates on bone
 Threads only engage far cortex
 Must be placed perpendicular to
the bone
 Best form of compression
 Poor shear, bending, and rotational
force resistance
 Can be accomplished with
 Partially threaded screw (lag by
design)
 Fully threaded screws (lag by
technique)

42.  Functional Lag Screw –
 the near cortex has been
drilled to the outer
diameter = compression
 Position Screw –
 the near cortex has
not been drilled to the
outer diameter = lack
of compression & fx
gap maintained
Use as sole technique of fixation is limited

43. Lag Screws
• Malposition of screw, or neglecting to countersink can lead to a
loss of reduction
• Ideally lag screw should pass perpendicular to fx

44.  Necessary for many fractures
 Requires specialized equipment and training
 Not readily available in many practices
 More expensive than pinning
Counter all the fracture forces
• Tension
• Compression
• Shear
• Bending
• Rotational forces

45. Bone plates should be placed on the
tension side of the bone

46. Plates are stronger if load sharing
with the bone occurs

47.  Scapula : Craniolateral
 Humerus : Craniolateral
 Radius : Craniomedial
 IIium : Lateral aspect
 Femur : Craniolateral
 Mandible : Lateral aspect
 Tibia : Medial aspect

48.  Reconstruct the bone
 Contour plate
 Drill, measure, and tap screw holes
(one by one)
 Apply screws from the fracture site
out, alternating bone fragments
 Engage at least six cortices per a
major bone fragment
 More for comminuted fractures if
possible

49. Using a flexible
aluminium
template
Using bending irons

50. • Plate protects primary repair from
weight-bearing forces (shear,
bending, and torsional forces across
fx)
• The weight-bearing load is shared
by both the plate and the bone
• Also called “Protection Plate"

51. • Mechanical compression added to the fracture site
• Reduce & Compress transverse or oblique fx’s
- Unable to use lag screw
• The weight-bearing load is shared by both the
plate and the bone
• Primary bone healing usually results
• Pre-bending plate
• External compression devices (tensioner)
• Dynamic compression with oval holes & eccentric
screw placement in plate

52. Prestress (Prebend) the plate at the level of the
fracture gap

53. • Spans a gap to prevent collapse of a
fracture
• All of the weight-bearing forces are
transmitted through the plate
• “Bridge”/bypass comminution
• Proximal & distal fixation
• Goal:
Maintain length, rotation, & axial alignment
Avoids soft tissue disruption at fx =
maintain fx blood supply

54. Compression, Neutralization
and Buttress are plate
application techniques
depending on the type of
fracture rather than design of
the plate

55.  The DCP is a special implant developed by the AO group for
compression and stabilization of a fracture
 Available in sizes
 2mm( Mini system),
 2.7mm,
 3.5mm narrow and broad ( Small fragment system),
 4.5mm narrow and broad ( Large system)
 DCP causes tension forces to be converted to compressive forces,
friction at fracture site > displacement force, eliminates
angulation, bending or rotation between bone fragments
 Mechanically, fixation is strong and stiff preventing micromotion (
Strain) at fracture interface
 Reduced strain( <2%) promotes contact healing

56. 2.7mm
4.5mm
3.5mm
•316L
• OVAL HOLES
WITH ‘RAMP’
ON ONE SIDE

57. ‘RAMP ‘

59.  Drilling of the hole in neutral/eccentric
position using eccentric/neutral drill guide

60. Load position (Yellow drill guide towards
fracture)-Tightening screw on the ‘ramp’ of
the plate produces a 1mm axial
compression

61. Neutral position ( Green guide) -
Tightening screw on the ‘ramp’ of the plate
produces a 0.1mm axial compression

62.  Plate is positioned on the
fragment. Insert first screw
near to fracture site using the
neutral drill guide on one
fragment.
 The second screw is inserted
using the eccentric drill guide
on the second fragment
 Subsequent screws are placed
using the neutral drill guide
 A minimum of three screws
each should be placed in the
proximal and distal fragments

65. TIBIAL FRACTURE REPAIR

69. DCP LC-DCP
WIDTH 10mm 11mm
THICKNESS 3.3mm 3.3mm
DISTANCE
BETWEEN
CENTER OF
HOLES
12mm 13mm
DISTANCE
BETWEEN
CENTER OF
HOLES
16mm NA
DCP vs LC-DCP ( 3.5mm )
‘MORPHOLOGY ‘

70.  DCP has a concave undersurface
 LC-DCP is thinner, scalloped between screw holes on contact
side of plate
 LC-DCP has no mid ‘belly’
DCP
LC-DCP

71. The scalloped undersurface of the LC-DCP serves two
purposes:
 Reduces plate-bone contact, promotes early revascularization
and healing of fractured bone and decreases osteoporosis
 Creates uniform strength along the plate, permits smooth
contouring, minimizes stress concentration along plate holes,
preempts stress protection
 The symmetrical bidirectional Dynamic Compression Unit (DCU)
screw hole permits compression in either direction anywhere
along the plate

73.  Oval holes permit screw angulation
 Wider angle of screw insertion with
LC-DCP
DEGREE OF
ANGULATIO
N
AXIAL PLANE TRANSVERSE
PLANE
DCP 70 250
LC-DCP 200 400

76.  DCP
 Dynamic Compression Plate
 LC-DCP
 Limited Contact
Dynamic Compression Plate
 LCP
 Locking Compression Plate

77.  Conventional plates
depend on friction
between the screw & bone
for stability
 Locking plates & screws
create fixed angles that do
not rely on screw
purchase in bone
Conventional
Screw & Plate
Locked
Screw & Plate

78. When conventional screw purchase may be
poor:
– Osteopenic bone
– Metaphyseal areas
– Periprosthetic fractures
– Failed fixation (nonunion)
– Screw strippage

79.  “Figure of eight” hole
design
 Locking screws
 Conventional cortex
& cancellous screws

80.  Threaded underside of head
 To thread (lock) into plate hole
 Larger core diameter:
 Increases strength
 Dissipates load over larger area of
bone
 Smaller thread pitch:
 Threads not used to generate
compression between plate and bone
Locking Screw Design
Cortex ScrewLocking Screw

81. Pre Reduced FractureLoss of Reduction

83. Non Reduced FractureNo Bone Alignment to the Plate

84. Pre Reduced FractureNo Fracture Malalignment

85.  Technique Requirements:
 Reduction absolutely essential first
 Lag before you lock

86.  Used for comminuted fracture
repair
 Decreases bending stress on plate
 Counteracts rotational and axial
forces
 IM pin only needs to fill 35-40% of
the canal diameter
 Monocortical screws are OK
 Make sure you engage enough
cortices

87.  Place operated limb in Modified
Robert Jones
 Encourage early use of operated
limb
 Client education is a must(The
owner must be made aware that
the animal would begin using the
limb long before fracture is healed)
 Periodic radiographic study to
assess healing of fractures is
essential

88. • In general, it is recommended that all
orthopedic implants be removed
• In practice, however, we rarely remove
orthopedic implants

89. Age Time
 Up to 3months One month
 3-6 months 2-3 months
 6-10 months 3-5 months
 Over 10 months 5-14 months

90.  Accomplishment of fracture healing
 Non Function/Screw loosening
plate breakage
 Irritation
 Infection
 Stress protection

91. • Inadequate fixation & stability
• Narrow, weak plate that is too short
• Insufficient cortices engaged with screws through plate
• Gaps left at the fx site
Unavoidable result = Nonunion
Failure

92.  Respect soft tissues
 Choose appropriate fixation method
 Achieve length, alignment, and rotational
control to permit motion as soon as possible
 Understand the requirements and
limitations of each method of internal
fixation