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PRINCIPLES OF INTERNAL FIXATION
By Dr Praveen
Principles (AO)
1. Anatomical reduction
2. Stable internal fixation
3. Preservation of the blood supply
4. Early active pain-free mobilisation
• Historical Background
• Preoperative Planning
• Fracture Reduction
• Techniques and Devices for Internal Fixation
Historical Background
• First reports on modern techniques of
internal fixation are only about 100 years
old.
• Elie and Albin Lambotte “osteosynthesis”
of
fractures with plates and screws, wire loops
and external fixators
• Brothers Elie and Albin Lambotte (1866-1955)
• Osteosynthesis
• Anatomical reduction and stable fixation of I/A #
Robert Danis (1880 to 1962)
introduced the term of soudure autogéne
Maurice Müller was impressed by DANIS &founded the
Arbeitsgemeinschaft für Osteosynthesefragen (AO) 1958
Gerhard Küntscher (1900 to 1972) in Germany had developed the
technique of IM nailing
GOAL OF OPERATIVE FRACTURE FIXATION
• Full restoration of function
• Faster return to his preinjury status
• Minimize the risk and incidence of complications.
• Predictable alignment of fracture fragments
The purpose of implants
to provide a temporary support
to maintain alignment during the
fracture healing
to allow for a functional rehabilitation
fractured bone needs
- a certain degree of immobilization
-optimally preserved blood supply
-biologic or hormonal stimuli
Soft Tissue Injury and Fracture Healing
“every fracture is a soft tissue injury,
where the bone happens to be broken,”
The more extensive the zone of injury and the
tissue destruction, the higher is the risk for a delay
of the healing process or for other complications
High Rate of Healing
Spectrum of Healing
Absolute Stability =
10 Bone Healing
Relative Stability =
20 Bone Healing
Biology of Bone Healing
THE SIMPLE VERSION...
Fibrous Matrix >
Cartilage > Calcified
Cartilage > Woven Bone >
Lamellar Bone
Haversian
Remodeling
Minimal
Callus
Callus
Functions of Fixation
• Interfragmentary
Compression
– Lag Screw
• Plate Functions
– Neutralization
– Buttress
– Bridge
– Tension Band
– Compression
– Locking
• Intramedullary Nails
– Internal splint
• Bridge plate fixation
– Internal splint
• External fixation
– External splint
• Cast
– External splint
*Not internal fixation
Indications for Internal Fixation
• Displaced intra-articular fracture
• Axial, angular, or rotational instability that
cannot be controlled by closed methods
• Open fracture
• Polytrauma
• Associated neurovascular injury
The components of a preoperative plan
• Timing of surgery
• Surgical approach
• Reduction maneuvers
• Fixation construct
• Intraoperative imaging
• Wound closure/coverage
• Postoperative care
• Rehabilitation
Prophylactic Antibiotics
• In general a second generation cephalosporin
with a broad spectrum is recommended,
applied as single dose
• 30 minutes before the start of surgery or for a
period of a maximum 24 to 48 hours
postoperatively
Fracture Reduction
• The goal of reduction is to restore the
anatomical relationship
– Direct reduction
– Indirect Reduction
– Closed reduction
– Open reduction
Reduction Forceps
joysticks
Collinear reduction clamp
Open Reduction
• Open reduction implies that the fracture site
is exposed, allowing to watch and inspect the
adequacy of reduction with our eyes.
The distractor
• Internal fixation devices stabilize the bone
– From within the medullary canal
(intramedullary nails)
– Fixed to the exterior of the bone (conventional
non locked screws and plates and locked plates
as well as tension band wires).
Screws
• A screw is a powerful element that converts
rotation into linear motion.
• They are typically named according to their
design, function, or way of application.
– Design (partially or fully threaded, cannulated, self-
tapping,etc.)
– Dimension of major thread diameter (most common
used 1.5, 2, 2.4, 2.7, 3.5, 4.5, 6.5, 7.3 mm, etc.)
• Area of typical application (cortex, cancellous
bone, bicortical,or monocortical)
• Function (lag screw, locking head screw [LHS],
position screw, etc.)
• The two basic principles of a conventional
screw are
– To compress a fracture plane (lag screw)
– To fix a plate to the bone (plate screw)
• Cortical screws:
–Greater number of threads
–smaller pitch
–Outer thread diameter to
core diameter ratio is less
–Better hold in cortical bone
–Usually fully threaded
–Size 1-4.5mm diameter
–Self tapping ,cannulated etc
Figure from: Rockwood and Green’s, 5th ed.
• Each size has a pair of drill bits corresponding
to the screws major and minor diameter and a
tap.
– The drill corresponding to the major diameter is
used for drilling the gliding hole for a lag screw
– The drill corresponding to the minor diameter is
used for drilling the threaded hole.
Cancellous screws:
- Larger thread to core diameter
ratio
- pitch is greater
- Lag effect with partially-
threaded screws
- Theoretically allows better
fixation in cancellous bone
- indicated for meta-epiphyseal ,
cancellous bone
Tapping is recommend to open the
cortex and in dense bone of the young
adult.
LHS
• The LHS have a head with a
thread that engages with the
reciprocal thread of the plate
hole.
• a screw-plate device with
angular stability
variable angular stability, which
allows angulating locking
screws within the plate hole to
address specific fracture
configurations
Name Mechanism Example
Nonlocked
Plate screw
Preload and friction is applied to
create force between the
plate and the bone
Forearm plating
Lag screw The glide hole allows compression
between bone fragments
Fixation of a butterfly or
wedge fragment or
medial malleolus fracture
Position screw Holds anatomical parts in correct
relation to each other without
compression
(i.e., thread hole only, no glide hole)
Syndesmotic screw
Locking head
screw
threads in the screw
head allow mechanical coupling to a
reciprocal thread in
the plate and provide angular stability
Complex metaphyseal #
Osteoporotic
Variable locking
screw
Used exclusively with special locked
plates; same mechanical angular
stability as locking head screw, but
allows some variability in screw
angulation within the
plate hole
Complex comminuted
metaphyseal fractures
and periprosthetic fractures
Interlocking
screw
Couples an intramedullary nail to the
bone to maintain
length, alignment, and rotation
Interlocked femoral or
tibial intramedullary nail
Anchor screw A point of fixation used to anchor a
wire loop or strong suture
Tension band anchor in a
proximal humerus
fracture
Push–pull screw A temporary point of fixation used
to reduce a fracture by
distraction and/or compression
Use of an articulated
compression device
Reduction screw Conventional screw used through a
plate to pull fracture fragments
toward the plate; the screw may be
removed or exchanged once
alignment is obtained
MIPO technique
to reduce
multifragmentary
fracture onto the plate
Poller screw Screw used as a fulcrum to redirect
an intramedullary nail
Proximal tibial fracture
during IM nailing
Lag screw
• Can be applied independently or through a plate hole.
• Interfragmentary compression is the basic element
responsible for absolute stability of fracture fixation.
• The ideal direction of a lag screw, for generation of
compressive force, is perpendicular to the fracture
plane.
• As this is often not practical, an inclination halfway
between the perpendiculars to the fracture and to
the long axis of the bone is typically chosen
Positioning Screw
*A fully threaded screw that
joins two anatomical parts at
a defined distance without
compression.
*The thread is therefore
tapped in both cortices.
*Example-Syndesmotic screw
Compression Plates
• Plate is pressed against the bone which produces
preload and friction between the two surfaces.
• USES
• #forearm bones ,
• simple metaphyseal # of long bones,
• malunion and nonunions,
Early modern plates
In 1967 the DCP designed by Perren
Angle blade plates for the proximal and distal femur
Tubular plates
Reconstruction plates
The sliding hip screw
Dynamic condylarscrews
LC-DCP LCP
THE FIVE FUNCTIONS OF PLATING
• Neutralization or protection
• Compression
• Buttressing
• Tension band function
• Bridging
Neutralization Plates
• Neutralizes/protects
lag screws from
shear, bending, and
torsional forces
across fx
• “Protection Plate"
Compression plate
• Produces locking forces across a # site.
• Role of compression
– Compaction of # to force together interdigitating
spicules
– space b/n bone fragments
– fracture stability
– Generate friction
– Absolute stability
• Methods of achieving compression
– Self compressing plate(coverts torque to longitudinal
force)
– Tensioning device
– Eccentric screw placement
– Lag screw
Dynamic compression principle
•
Axial compression with a plate can be obtained with the
removable, articulated tension device
Verbrugg forceps used for tensioning
Lag screw placement through
the plate
• Compression +
rigidity obtained
a with one
construct
• Compression
plate first
• Then lag screw
placed through
plate
• In oblique fractures the plate must be fixed
first to the fragment with an obtuse angle, so
that when compression is added on the
opposite side of the fracture the fragment
locks in the axilla between the plate and the
bone
The structure of a limited-contact dynamic compression plate.
LC-DCP
In the dynamic compression plate (A), the area at the
plate holes is less stiff than the area between them.
During bending, the plate tends to bend only in the areas
of the hole. The limited-contact dynamic compression
plate (B) has an even stiffness without the risk of
buckling at the screw holes.
• Undercuts plate holes; undercut at each end
of the plate hole allows 40 tilting of screws
both ways along the long axis of the plate and
7 degrees tilting in transverse plane
Tension Band Plates
• Plate counteracts natural
bending moment seen wih
physiologic loading of bone
– Applied to tension side to
prevent “gapping”
– Plate converts bending force
to compression
– Examples: Proximal Femur &
Olecranon
Buttress plate
• Strengthen a weakened cortex.
• Prevents bone from collapsing during healing.
• Usually with large surface area to facilitate
wider distribution of the load.
• Plate must match contour of bone to truly
provide buttress effect
• To maintain bone length or support depressed
fracture fragments.
• Commmonly used in fixing epiphyseal and
metaphyseal fractures.
• Order of fixation:
• Articular surface compressed with
bone forceps and provisionally fixed
with k-wires
1. Bottom 3 cortical screws placed
• Provide buttress effect
2. Top 2 partially-threaded cancellous
screws placed
• Lag articular surface together
3. Third screw placed either in lag or
normal fashion since articular
surface already compressed
Buttress Concepts
Figure from: Schatzker J, Tile M: The Rationale of
Operative Fracture Care. Springer-Verlag, 1987.
Antiglide plate
Bridge Plates
• “Bridge”/bypass comminution
• Do not produce any compression
• Proximal & distal fixation
• Goal:
– Maintain length, rotation, & axial alignment
• Avoids soft tissue disruption at # = maintain # blood
supply
Condylar plate
• Mainly used in Rx of I/A distal femoral fractures.
• Two mechanical functions
– Maintains reduction of manjor intra-articular fragments
– Rigidly fixes metaphyseal componets to diaphyseal
shaft,permitting early movements of extremity.
– Functions both as neutralizatio and buttresssing plate
– It can also function as compression plate
Plate Pre-Bending Compression
Forces opposite cortex into compression
Application of straight plate to curved bone
Effect of forces
Torsional stability
Counting number of engaged cortices
Longer plates reduce stress in the
plate as well as to th screws
HOW MANY SCREWS ?
• Hands-on experience suggests that, in the humerus,
screws grip seven cortices on each side of the
fracture ; in the radius and the ulna, five; in the tibia,
six, and in the femur, seven.
Bones No. of Cortices No. of Holes Type of
Plate
Forearm 5 to 6 Cortex 6 holes Small 3.5
Humerus 7 to 8 Cortex 8 holes Narrow 4.5
Tibia 7 to 8 Cortex 7 holes Narrow 4.5
Femur 7 to 8 Cortex 8 holes Narrow 4.5
Clavicle 5 to 6 Cortex 6 holes` Small 3.5
HOW CLOSE TO THE FRACTURE SITE?
• A screw, as a result, should not be placed
closer than one centimeter from the fracture
line.
• Classic example of
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 to Apply Concepts
Reconstruction Plates
• Can be bent and twisted in two dimensions.
• Decrease stiffness than DCP.
• Should not be bent more than 15°.
• Used were the exact and complex contouring
is required.
– eg. Pelvis, Distal Humerus, Clavicle.
Reconstruction plates are thicker than one third tubular plates but
not quite as thick as dynamic compression plates. As with tubular
plates, they have oval screw holes, allowing potential for limited
compression.
One Third Tubular Plates
• Plates have the form of one third of the
circumference of a cylinder.
• Low rigidity (1mm thick).
• Oval holes –
Axial compression can be achieved.
• Uses –
– Lateral malleolus,
– distal ulna,
– metatarsals.
limited stability. The thin design allows for easy shaping
and is primarily used on the lateral malleolus and distal
ulna. The oval holes allow for limited fracture
compression with eccentric screw placement.
LOCKING PLATES
• The force transfer in
the internal fixator
principle occurs
primarily through
the locking head
screws (LHS) across
the plate and
fracture
• Angular stability of the construct
• Improved construct stability in osteopenic
bone
• Resistance to secondary collapse or screw
displacement
• Screw head has threads that
lock into threaded hole in
the plate
• Creates a “fixed angle” at
each hole
• Theoretically eliminates
individual screw failure
• Plate-bone contact not
critical Courtesy AO Archives
• Increased axial
stability
• It is much less likely
that an individual
screw will fail
• But, plates can still
break
• Indications:
– Osteopenic bone
– Metaphyseal
fractures with short
articular block
– Bridge plating
Screw :
• Conical screw head
• Large core diameter.
• Self tapping.
• Star drive recess.
• 1st reduced the # as anatomical as possible
• Cortical screw should be used 1st in a fracture
fragment.
• If locking screw is used first avoid spinning of
plates.
• Unicortical screws causes no loss of stability
• Osteoporotic bones bicortical screws should
be used.
• In the comminuted # screw holes close to the
fracture should be used to reduce stain.
• In the fracture with small or no gap the
immediate screw holes should be left unfilled
to reduced the strain
Indications :
1. Osteoporotic #
2. Periprosthetic #
3. Multifragmentry #
4. Delayed change from external fixation to internal
fixation.
Advantages :
1. Angular stability
2. Axial stability
3. Plate contouring not required
4. Less damage to the blood supply of bone.
5. Decrease infection because of submuscular technique
6. Less soft tissue damage.
Plate screw density and fracture plate quotient
Plate length and No. of Screws
Plate span ratio Plate length
# length
Comminuted # - 2-3
Simple # - 8-10
Plate Screw density No. of Screws
No. of Plate holes
Simple #-0.3-0.4
Comminuted # 0.4-0.5
- At least 4 cortices per main fragment for comminuted
fracture
- At least 3 cortices per main fragment for simple fracture.
Timing of Plate Removal, Recommendations
for removal of plates in the lower limb :
• Malleolar fractures-8-12
• The tibial pilon-12-18
• The tibial shaft-12-18
• The proximal tibia -12-18
• Shaft of radius / ulna-24-28
• Distal radius 8-12
• Metacarpals 4-6
• The femoral condyles-12-24
• The femoral shaft: Single plate, Double Plate-24-36
From month 18, in 2 steps ( Interval 06 months)
• Pertrochanteric and femoral neck fractures Upper
extremity-12-18
Combi plates
• Hybrid plating with a combination of
conventional nonlocked screws and locked
screws
• lag first, lock second
INTRAMEDULLARY NAILING
• Load sharing device
• Axial and rotational stability
• Maintains the length
• Biological fixation
• Minimal soft tissue exposure
• Early weight bearing
Intramedullary Nailing :
• The principle of fixation is based on the
compression between the bone and the nail.
Interlocking Intramedullary Nail :
• Nail have the proximal and distal screw holes.
Nail is locked by the interlocking screws. The
resistance to the torsial and axial force depend
on the screw bone interface.
Working Length :
• Distance between the proximal and distal
interlocking screws.
Dyanamization :
• Interlocking Nails can be locked in dynamic or
static mode.
• Dyanamization means placing the screw at only
one end of the bone.
Static Locking means placing the screw at the both
ends of the bone.
• Dynamization can be done at the 8-12 weeks
for delayed union.
• Screw is removed from the longer fragment.
TYPES OF INTRAMEDULLARY NAILS :
• Centromedullary nails
• Condylocephalic nails
• Cephalomedullary nails
Blk screws.
Working Length
Intramedullary Fixation
• Generally utilizes closed/indirect or minimally
open reduction techniques
• Greater preservation of soft tissues as
compared to ORIF
• IM reaming has been shown to stimulate
fracture healing
• Expanded indications i.e. Reamed IM nail is
acceptable in many open fractures
Intramedullary Fixation
• Rotational and axial
stability provided by
interlocking bolts
• Reduction can be
technically difficult in
segmental and
comminuted fractures
• Difficult to Maintain
reduction of fractures
in close proximity to
metaphyseal flare
• Open segmental
tibia fracture treated
with a reamed,
locked IM Nail.
• Note the use of
multiple proximal
interlocks where
angular control is
more difficult to
maintain due to the
metaphyseal
flare.
• Intertrochanteric/
Subtrochanteric fracture
treated with closed IM
Nail
• The goal:
• Restore length,
alignment, and
rotation
• NOT anatomic
reduction
• Without extensive
exposure this fracture
formed abundant callus
by 6 weeks
Valgus is restored...
Percutaneous Plating
• Plating through modified
incisions
– Indirect reduction
techniques
– Limited incision for:
• Passing and
positioning the
plate
• Individual screw
placement
– Soft tissue “friendly”
DYNAMIC HIP SCREW & DYNAMIC
CONDYLAR SCREW
• The dynamic hip screw (DHS) implant system has been
designed primarily for the fixation of trochanteric
fractures. It may also be used for certain
subtrochanteric fractures as well as for selected basi-
cervical femoral fractures.
• The implant is based on the sliding nail principle which
allows impaction of the fracture. This is made
possible by the insertion of a wide diameter screw
into the femoral head. A side plate, which has barrel
at a fixed angle is slid over the screw and fixed to the
femoral shaft.
DHS :
• Length of measurements :
• Length measured 105 mm
• Reamer setting 95 mm
• Tapping depth 95 mm
• DHS/DCS Screw length 95 mm
Should be less than 28mm
CCS Fixation in Fracture Neck Femur :
- Parallel 6.5mm CCS are used in triangular or inverted
triangular configuration.
Tension Band Wiring
wire absorbs tensile forces,
the bone withstands the compressive forces
• Wire must be applied on tension surface of
bone.
• Wire must be prestressed(tightened)
• Wire must be strong enough to withstand
tension load.
• Strong opposite bone cortex must be present.
• Joint movement must be encouraged to
improve congruity and compression
Biomechanics – Pauwels 1935
Biomechanics
Biomechanics
Biomechanics
The cortex from the TBW must be strong enough to bear
the applied compressive loads
Biomechanics
• The implant alone does not provide stability.
• In combination with antagonistic deforming
muscles, it can help produce uniform
compression at the fracture site. It guides the
compression force.
Biomechanics
Tension Band Wiring is a device, which convert
distraction forces of extensors acting on the
fracture line into compressive forces
Bilateral cable ension band operation
Treatment options for comminuted
patella fractures
Comminuted fracture –circlage wire
and K wire fixation
Cerclage wiring
• Long spiral or oblique #.
• Obtain reduction.
• Place wires perpendicular to long axis of bone.
• Adequately spaced multiple wire loops.
• Contour wires around bone.
• Tension and tighten.
Always
• Use strong wire
• Use two or more wires
• Use wire tightener –twister
• Apply equal tension on all wires
• Twist in same direction
• Support # with addition means(never sole
means of # stabilization)
Thankyou

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Principles of internal fixation

  • 1. PRINCIPLES OF INTERNAL FIXATION By Dr Praveen
  • 2. Principles (AO) 1. Anatomical reduction 2. Stable internal fixation 3. Preservation of the blood supply 4. Early active pain-free mobilisation
  • 3. • Historical Background • Preoperative Planning • Fracture Reduction • Techniques and Devices for Internal Fixation
  • 4. Historical Background • First reports on modern techniques of internal fixation are only about 100 years old. • Elie and Albin Lambotte “osteosynthesis” of fractures with plates and screws, wire loops and external fixators
  • 5. • Brothers Elie and Albin Lambotte (1866-1955) • Osteosynthesis • Anatomical reduction and stable fixation of I/A #
  • 6. Robert Danis (1880 to 1962) introduced the term of soudure autogéne
  • 7. Maurice Müller was impressed by DANIS &founded the Arbeitsgemeinschaft für Osteosynthesefragen (AO) 1958
  • 8. Gerhard Küntscher (1900 to 1972) in Germany had developed the technique of IM nailing
  • 9. GOAL OF OPERATIVE FRACTURE FIXATION • Full restoration of function • Faster return to his preinjury status • Minimize the risk and incidence of complications. • Predictable alignment of fracture fragments
  • 10. The purpose of implants to provide a temporary support to maintain alignment during the fracture healing to allow for a functional rehabilitation
  • 11. fractured bone needs - a certain degree of immobilization -optimally preserved blood supply -biologic or hormonal stimuli
  • 12. Soft Tissue Injury and Fracture Healing “every fracture is a soft tissue injury, where the bone happens to be broken,” The more extensive the zone of injury and the tissue destruction, the higher is the risk for a delay of the healing process or for other complications
  • 13. High Rate of Healing Spectrum of Healing Absolute Stability = 10 Bone Healing Relative Stability = 20 Bone Healing Biology of Bone Healing THE SIMPLE VERSION... Fibrous Matrix > Cartilage > Calcified Cartilage > Woven Bone > Lamellar Bone Haversian Remodeling Minimal Callus Callus
  • 14. Functions of Fixation • Interfragmentary Compression – Lag Screw • Plate Functions – Neutralization – Buttress – Bridge – Tension Band – Compression – Locking • Intramedullary Nails – Internal splint • Bridge plate fixation – Internal splint • External fixation – External splint • Cast – External splint *Not internal fixation
  • 15. Indications for Internal Fixation • Displaced intra-articular fracture • Axial, angular, or rotational instability that cannot be controlled by closed methods • Open fracture • Polytrauma • Associated neurovascular injury
  • 16. The components of a preoperative plan • Timing of surgery • Surgical approach • Reduction maneuvers • Fixation construct • Intraoperative imaging • Wound closure/coverage • Postoperative care • Rehabilitation
  • 17. Prophylactic Antibiotics • In general a second generation cephalosporin with a broad spectrum is recommended, applied as single dose • 30 minutes before the start of surgery or for a period of a maximum 24 to 48 hours postoperatively
  • 18. Fracture Reduction • The goal of reduction is to restore the anatomical relationship – Direct reduction – Indirect Reduction – Closed reduction – Open reduction
  • 22. Open Reduction • Open reduction implies that the fracture site is exposed, allowing to watch and inspect the adequacy of reduction with our eyes.
  • 23.
  • 25. • Internal fixation devices stabilize the bone – From within the medullary canal (intramedullary nails) – Fixed to the exterior of the bone (conventional non locked screws and plates and locked plates as well as tension band wires).
  • 26. Screws • A screw is a powerful element that converts rotation into linear motion. • They are typically named according to their design, function, or way of application. – Design (partially or fully threaded, cannulated, self- tapping,etc.) – Dimension of major thread diameter (most common used 1.5, 2, 2.4, 2.7, 3.5, 4.5, 6.5, 7.3 mm, etc.)
  • 27. • Area of typical application (cortex, cancellous bone, bicortical,or monocortical) • Function (lag screw, locking head screw [LHS], position screw, etc.)
  • 28. • The two basic principles of a conventional screw are – To compress a fracture plane (lag screw) – To fix a plate to the bone (plate screw)
  • 29. • Cortical screws: –Greater number of threads –smaller pitch –Outer thread diameter to core diameter ratio is less –Better hold in cortical bone –Usually fully threaded –Size 1-4.5mm diameter –Self tapping ,cannulated etc Figure from: Rockwood and Green’s, 5th ed.
  • 30. • Each size has a pair of drill bits corresponding to the screws major and minor diameter and a tap. – The drill corresponding to the major diameter is used for drilling the gliding hole for a lag screw – The drill corresponding to the minor diameter is used for drilling the threaded hole.
  • 31. Cancellous screws: - Larger thread to core diameter ratio - pitch is greater - Lag effect with partially- threaded screws - Theoretically allows better fixation in cancellous bone - indicated for meta-epiphyseal , cancellous bone Tapping is recommend to open the cortex and in dense bone of the young adult.
  • 32. LHS • The LHS have a head with a thread that engages with the reciprocal thread of the plate hole. • a screw-plate device with angular stability variable angular stability, which allows angulating locking screws within the plate hole to address specific fracture configurations
  • 33. Name Mechanism Example Nonlocked Plate screw Preload and friction is applied to create force between the plate and the bone Forearm plating Lag screw The glide hole allows compression between bone fragments Fixation of a butterfly or wedge fragment or medial malleolus fracture Position screw Holds anatomical parts in correct relation to each other without compression (i.e., thread hole only, no glide hole) Syndesmotic screw
  • 34. Locking head screw threads in the screw head allow mechanical coupling to a reciprocal thread in the plate and provide angular stability Complex metaphyseal # Osteoporotic Variable locking screw Used exclusively with special locked plates; same mechanical angular stability as locking head screw, but allows some variability in screw angulation within the plate hole Complex comminuted metaphyseal fractures and periprosthetic fractures Interlocking screw Couples an intramedullary nail to the bone to maintain length, alignment, and rotation Interlocked femoral or tibial intramedullary nail
  • 35. Anchor screw A point of fixation used to anchor a wire loop or strong suture Tension band anchor in a proximal humerus fracture Push–pull screw A temporary point of fixation used to reduce a fracture by distraction and/or compression Use of an articulated compression device Reduction screw Conventional screw used through a plate to pull fracture fragments toward the plate; the screw may be removed or exchanged once alignment is obtained MIPO technique to reduce multifragmentary fracture onto the plate Poller screw Screw used as a fulcrum to redirect an intramedullary nail Proximal tibial fracture during IM nailing
  • 36. Lag screw • Can be applied independently or through a plate hole. • Interfragmentary compression is the basic element responsible for absolute stability of fracture fixation.
  • 37. • The ideal direction of a lag screw, for generation of compressive force, is perpendicular to the fracture plane. • As this is often not practical, an inclination halfway between the perpendiculars to the fracture and to the long axis of the bone is typically chosen
  • 38.
  • 39.
  • 40. Positioning Screw *A fully threaded screw that joins two anatomical parts at a defined distance without compression. *The thread is therefore tapped in both cortices. *Example-Syndesmotic screw
  • 41. Compression Plates • Plate is pressed against the bone which produces preload and friction between the two surfaces. • USES • #forearm bones , • simple metaphyseal # of long bones, • malunion and nonunions,
  • 42. Early modern plates In 1967 the DCP designed by Perren Angle blade plates for the proximal and distal femur Tubular plates Reconstruction plates The sliding hip screw Dynamic condylarscrews LC-DCP LCP
  • 43. THE FIVE FUNCTIONS OF PLATING • Neutralization or protection • Compression • Buttressing • Tension band function • Bridging
  • 44. Neutralization Plates • Neutralizes/protects lag screws from shear, bending, and torsional forces across fx • “Protection Plate"
  • 45. Compression plate • Produces locking forces across a # site. • Role of compression – Compaction of # to force together interdigitating spicules – space b/n bone fragments – fracture stability – Generate friction – Absolute stability
  • 46. • Methods of achieving compression – Self compressing plate(coverts torque to longitudinal force) – Tensioning device – Eccentric screw placement – Lag screw
  • 48. Axial compression with a plate can be obtained with the removable, articulated tension device
  • 49. Verbrugg forceps used for tensioning
  • 50.
  • 51.
  • 52. Lag screw placement through the plate • Compression + rigidity obtained a with one construct • Compression plate first • Then lag screw placed through plate
  • 53. • In oblique fractures the plate must be fixed first to the fragment with an obtuse angle, so that when compression is added on the opposite side of the fracture the fragment locks in the axilla between the plate and the bone
  • 54.
  • 55. The structure of a limited-contact dynamic compression plate. LC-DCP
  • 56. In the dynamic compression plate (A), the area at the plate holes is less stiff than the area between them. During bending, the plate tends to bend only in the areas of the hole. The limited-contact dynamic compression plate (B) has an even stiffness without the risk of buckling at the screw holes.
  • 57. • Undercuts plate holes; undercut at each end of the plate hole allows 40 tilting of screws both ways along the long axis of the plate and 7 degrees tilting in transverse plane
  • 58. Tension Band Plates • Plate counteracts natural bending moment seen wih physiologic loading of bone – Applied to tension side to prevent “gapping” – Plate converts bending force to compression – Examples: Proximal Femur & Olecranon
  • 59.
  • 60. Buttress plate • Strengthen a weakened cortex. • Prevents bone from collapsing during healing. • Usually with large surface area to facilitate wider distribution of the load. • Plate must match contour of bone to truly provide buttress effect
  • 61. • To maintain bone length or support depressed fracture fragments. • Commmonly used in fixing epiphyseal and metaphyseal fractures.
  • 62. • Order of fixation: • Articular surface compressed with bone forceps and provisionally fixed with k-wires 1. Bottom 3 cortical screws placed • Provide buttress effect 2. Top 2 partially-threaded cancellous screws placed • Lag articular surface together 3. Third screw placed either in lag or normal fashion since articular surface already compressed Buttress Concepts Figure from: Schatzker J, Tile M: The Rationale of Operative Fracture Care. Springer-Verlag, 1987.
  • 64. Bridge Plates • “Bridge”/bypass comminution • Do not produce any compression • Proximal & distal fixation • Goal: – Maintain length, rotation, & axial alignment • Avoids soft tissue disruption at # = maintain # blood supply
  • 65.
  • 66. Condylar plate • Mainly used in Rx of I/A distal femoral fractures. • Two mechanical functions – Maintains reduction of manjor intra-articular fragments – Rigidly fixes metaphyseal componets to diaphyseal shaft,permitting early movements of extremity. – Functions both as neutralizatio and buttresssing plate – It can also function as compression plate
  • 67.
  • 68.
  • 69. Plate Pre-Bending Compression Forces opposite cortex into compression
  • 70.
  • 71. Application of straight plate to curved bone
  • 73.
  • 74.
  • 75.
  • 77. Counting number of engaged cortices
  • 78. Longer plates reduce stress in the plate as well as to th screws
  • 79. HOW MANY SCREWS ? • Hands-on experience suggests that, in the humerus, screws grip seven cortices on each side of the fracture ; in the radius and the ulna, five; in the tibia, six, and in the femur, seven. Bones No. of Cortices No. of Holes Type of Plate Forearm 5 to 6 Cortex 6 holes Small 3.5 Humerus 7 to 8 Cortex 8 holes Narrow 4.5 Tibia 7 to 8 Cortex 7 holes Narrow 4.5 Femur 7 to 8 Cortex 8 holes Narrow 4.5 Clavicle 5 to 6 Cortex 6 holes` Small 3.5
  • 80. HOW CLOSE TO THE FRACTURE SITE? • A screw, as a result, should not be placed closer than one centimeter from the fracture line.
  • 81. • Classic example of 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 to Apply Concepts
  • 82. Reconstruction Plates • Can be bent and twisted in two dimensions. • Decrease stiffness than DCP. • Should not be bent more than 15°. • Used were the exact and complex contouring is required. – eg. Pelvis, Distal Humerus, Clavicle.
  • 83. Reconstruction plates are thicker than one third tubular plates but not quite as thick as dynamic compression plates. As with tubular plates, they have oval screw holes, allowing potential for limited compression.
  • 84. One Third Tubular Plates • Plates have the form of one third of the circumference of a cylinder. • Low rigidity (1mm thick). • Oval holes – Axial compression can be achieved. • Uses – – Lateral malleolus, – distal ulna, – metatarsals.
  • 85. limited stability. The thin design allows for easy shaping and is primarily used on the lateral malleolus and distal ulna. The oval holes allow for limited fracture compression with eccentric screw placement.
  • 86. LOCKING PLATES • The force transfer in the internal fixator principle occurs primarily through the locking head screws (LHS) across the plate and fracture
  • 87. • Angular stability of the construct • Improved construct stability in osteopenic bone • Resistance to secondary collapse or screw displacement
  • 88. • Screw head has threads that lock into threaded hole in the plate • Creates a “fixed angle” at each hole • Theoretically eliminates individual screw failure • Plate-bone contact not critical Courtesy AO Archives
  • 89. • Increased axial stability • It is much less likely that an individual screw will fail • But, plates can still break • Indications: – Osteopenic bone – Metaphyseal fractures with short articular block – Bridge plating
  • 90.
  • 91. Screw : • Conical screw head • Large core diameter. • Self tapping. • Star drive recess.
  • 92. • 1st reduced the # as anatomical as possible • Cortical screw should be used 1st in a fracture fragment. • If locking screw is used first avoid spinning of plates. • Unicortical screws causes no loss of stability
  • 93. • Osteoporotic bones bicortical screws should be used. • In the comminuted # screw holes close to the fracture should be used to reduce stain. • In the fracture with small or no gap the immediate screw holes should be left unfilled to reduced the strain
  • 94. Indications : 1. Osteoporotic # 2. Periprosthetic # 3. Multifragmentry # 4. Delayed change from external fixation to internal fixation. Advantages : 1. Angular stability 2. Axial stability 3. Plate contouring not required 4. Less damage to the blood supply of bone. 5. Decrease infection because of submuscular technique 6. Less soft tissue damage.
  • 95. Plate screw density and fracture plate quotient
  • 96. Plate length and No. of Screws Plate span ratio Plate length # length Comminuted # - 2-3 Simple # - 8-10 Plate Screw density No. of Screws No. of Plate holes Simple #-0.3-0.4 Comminuted # 0.4-0.5 - At least 4 cortices per main fragment for comminuted fracture - At least 3 cortices per main fragment for simple fracture.
  • 97. Timing of Plate Removal, Recommendations for removal of plates in the lower limb : • Malleolar fractures-8-12 • The tibial pilon-12-18 • The tibial shaft-12-18 • The proximal tibia -12-18 • Shaft of radius / ulna-24-28 • Distal radius 8-12 • Metacarpals 4-6
  • 98. • The femoral condyles-12-24 • The femoral shaft: Single plate, Double Plate-24-36 From month 18, in 2 steps ( Interval 06 months) • Pertrochanteric and femoral neck fractures Upper extremity-12-18
  • 99. Combi plates • Hybrid plating with a combination of conventional nonlocked screws and locked screws • lag first, lock second
  • 100. INTRAMEDULLARY NAILING • Load sharing device • Axial and rotational stability • Maintains the length • Biological fixation • Minimal soft tissue exposure • Early weight bearing
  • 101. Intramedullary Nailing : • The principle of fixation is based on the compression between the bone and the nail. Interlocking Intramedullary Nail : • Nail have the proximal and distal screw holes. Nail is locked by the interlocking screws. The resistance to the torsial and axial force depend on the screw bone interface. Working Length : • Distance between the proximal and distal interlocking screws.
  • 102. Dyanamization : • Interlocking Nails can be locked in dynamic or static mode. • Dyanamization means placing the screw at only one end of the bone. Static Locking means placing the screw at the both ends of the bone. • Dynamization can be done at the 8-12 weeks for delayed union. • Screw is removed from the longer fragment.
  • 103. TYPES OF INTRAMEDULLARY NAILS : • Centromedullary nails • Condylocephalic nails • Cephalomedullary nails
  • 105. Intramedullary Fixation • Generally utilizes closed/indirect or minimally open reduction techniques • Greater preservation of soft tissues as compared to ORIF • IM reaming has been shown to stimulate fracture healing • Expanded indications i.e. Reamed IM nail is acceptable in many open fractures
  • 106. Intramedullary Fixation • Rotational and axial stability provided by interlocking bolts • Reduction can be technically difficult in segmental and comminuted fractures • Difficult to Maintain reduction of fractures in close proximity to metaphyseal flare
  • 107. • Open segmental tibia fracture treated with a reamed, locked IM Nail. • Note the use of multiple proximal interlocks where angular control is more difficult to maintain due to the metaphyseal flare.
  • 108. • Intertrochanteric/ Subtrochanteric fracture treated with closed IM Nail • The goal: • Restore length, alignment, and rotation • NOT anatomic reduction • Without extensive exposure this fracture formed abundant callus by 6 weeks Valgus is restored...
  • 109. Percutaneous Plating • Plating through modified incisions – Indirect reduction techniques – Limited incision for: • Passing and positioning the plate • Individual screw placement – Soft tissue “friendly”
  • 110. DYNAMIC HIP SCREW & DYNAMIC CONDYLAR SCREW • The dynamic hip screw (DHS) implant system has been designed primarily for the fixation of trochanteric fractures. It may also be used for certain subtrochanteric fractures as well as for selected basi- cervical femoral fractures. • The implant is based on the sliding nail principle which allows impaction of the fracture. This is made possible by the insertion of a wide diameter screw into the femoral head. A side plate, which has barrel at a fixed angle is slid over the screw and fixed to the femoral shaft.
  • 111. DHS : • Length of measurements : • Length measured 105 mm • Reamer setting 95 mm • Tapping depth 95 mm • DHS/DCS Screw length 95 mm
  • 112. Should be less than 28mm
  • 113. CCS Fixation in Fracture Neck Femur : - Parallel 6.5mm CCS are used in triangular or inverted triangular configuration.
  • 114. Tension Band Wiring wire absorbs tensile forces, the bone withstands the compressive forces
  • 115. • Wire must be applied on tension surface of bone. • Wire must be prestressed(tightened) • Wire must be strong enough to withstand tension load. • Strong opposite bone cortex must be present. • Joint movement must be encouraged to improve congruity and compression
  • 119. Biomechanics The cortex from the TBW must be strong enough to bear the applied compressive loads
  • 120. Biomechanics • The implant alone does not provide stability. • In combination with antagonistic deforming muscles, it can help produce uniform compression at the fracture site. It guides the compression force.
  • 121. Biomechanics Tension Band Wiring is a device, which convert distraction forces of extensors acting on the fracture line into compressive forces
  • 122.
  • 123. Bilateral cable ension band operation
  • 124. Treatment options for comminuted patella fractures
  • 125. Comminuted fracture –circlage wire and K wire fixation
  • 126. Cerclage wiring • Long spiral or oblique #. • Obtain reduction. • Place wires perpendicular to long axis of bone. • Adequately spaced multiple wire loops. • Contour wires around bone. • Tension and tighten.
  • 127. Always • Use strong wire • Use two or more wires • Use wire tightener –twister • Apply equal tension on all wires • Twist in same direction • Support # with addition means(never sole means of # stabilization)