platesandscrews11-150511092130-lva1-app6892.pdf

Plates and screws

1. Plates and Screws
Supervised by Dr. MarwanAbuhashem
By Dr. IsmaelAl-jabiri
Al-BashirOrthopedic Department
Ministry Of Health Jordan

2. 1.Anatomical Reduction.
2.Stable internal fixation.
3.Preservation of Blood supply
4.Early mobilization.
Principles of Fixation :

3. 3
•“Surfaces of the fracture do not displace under
functional load”
•Can only be achieved by interfragmentary
compression
Absolute stability
•A plate by itself rarely provides absolute stability
•The key tool of absolute stability is the lag screw
•Compression must sufficiently neutralize all forces[bending,
tension, shear and rotation]

4. Relative Stability:
A fixation device that allows small amounts
of motionin proportion to the load applied.
The deformation or displacement is inversely
proportional to the stiffness of the implant.
Examples: Intramedullaryrod, bridge plating,
external fixation.

5. PLATES
Introduction:
Boneplatesarelikeinternalsplintsholding
togetherthefracturedendsofabone.
Aboneplatehastwomechanicalfunctions.
•Ittransmitsforcesfromoneendofabonetothe
other,bypassingandthusprotectingtheareaof
fractures.
•Italsoholdsthefractureendstogetherwhile
maintainingtheproperalignmentofthefragments
throughoutthehealingprocess.

6. History
Hansman’sBone Plate
(1886)
Hansmann’splates were:
Bent at the end to protudethrough the skin
Attchedto bone by screw with long shanks
that projected outside the soft tissues.

7. Bone Suture Stabilization
Inserts (Koenig, 1905)

8. History
Since 1958, AO has devised a
family of plates for long bone
fractures, starting with a round
holed plate.
In 1969 the Dynamic
Compression Plate was
developed.
In 1994 LC DCP was created.
In 2011 LCP with combination
holes has come into use.

9. Names of plates.
1.Shape (Semitubular, 1/3
rd
tubular)
2.Width of plate (Small, Narrow, Broad)
3.Shape of screw holes. (Round, Oval)
4.Surface contact characteristics. (LC, PC)
5.Intended site of application (Condylar Plate)
6.According to the function

10. Standard Plates
Narrow DCP-4.5 mm
Broad DCP –4.5 mm
3.5 mm DCP

11. LC-DCP 3.5 & 4.5mm
Reconstruction plate
3.5 & 4.5mm

12. 1/3 tubular plate 2.7,
3.5 & 4.5 mm

13. Special Plates
T Plates
T&L Buttress plates

14. Lateral proximal Tibial
buttress plates
Condylarbuttress plate
Narrow lengthening
plates

15. Broad Lengthening
plate
Spoon plate
Clover leaf plate

16. DCP -3.5 and 4.5
First introduced in 1969 by Danis
Revolutionary concept of compression plating
Featured a new hole designed for axial compression
Broad 4.5 for Femur & Narrow 4.5 for Humerus&
Tibia
DCP 3.5 for Forearm, Fibula, Pelvis & Clavicle

17. Advantage of DCP :
1.Inclinedinsertion25°longitudinaland7°
sideways
2.Placementofascrewinneutralposition
withoutthedangerofdistractionoffragments
3.Insertionofalagscrewforthecompression
4.Usageoftwolagscrewsinthemainfragments
foraxialcompression
5.Compressionofseveralfragmentsindividually
incomminutedfractures
6.Applicationasabuttressplateinarticulararea

18. Problems with DCP
Unstable fixation leads to fatigue & failure
Strict adherence to principles of compression
Compromised blood supply due to intimate
contact with underlying cortex
“Refractures” after plate removal

19. LC-DCP
Represents a design change
Overcome problems with DCP
Plate footprint reduced
Minimized kinking at screw holes, more
countourable, reduced plate fatigue at
hole
Allows more inclination of screw in
longitudinal plane and transverse
plane.

20. In the DCP (A), the area at the plate holes is less stiff than
the area between them so while bending, the plate tends
to bend only in the areas of the hole.
The LC-DCP(B) has an even stiffness without the risk of
buckling at the screw holes.

21. TheLC-DCPoffersadditionaladvantage
Improvebloodcirculationbyminimizingplate-
bonecontact
Moreevenlydistributionofstiffnessthrough
theplate
Allowssmallbonebridgebeneaththeplate

22. Tubular plates
3.5 system -1/3
rd
Tubular
4.5 system -Semitubular
Limited stability
-Ovalholes–Axialcompression
canbeachieved.
-Lowrigidity(1mmthick).
Lateral malleolus
Distal ulna / Olecranon
Distal humerus

23. limited stability. The thin design allows for easy shaping
and is primarily used on the lateral malleolusand distal
ulna. The oval holes allow for limited fracture
compression with eccentric screw placement.

24. Reconstruction plates
Deep notches between holes
Accurate contouring in any
plane
Pelvis
Acetabulum
Distal humerus
Clavicle
Olecranon

25. Reconstruction plates are thicker than third tubular plates but not
quite as thick as dynamic compression plates. Designed with deep
notches between the holes, they can be contoured in 3 planes to fit
complex surfaces, as around the pelvis and acetabulum.
Reconstruction plates are provided in straight and slightly thicker and
stiffer precurvedlengths. As with tubular plates, they have oval screw
holes, allowing potential for limited compression.

26. LCP –Locking Compression Plate

27. LCP
Latest in the evolution
“ Internal fixator ”
Combination of locking
screw with
conventional screw
Extraperiosteal
location of plate

28. LCP: internal external fixator

29. LCP
Combines advantages
of DCP principle and
locking head principle.
Flexibility of choice
within a single implant.
Screw hole have been
specially designed to
accept either: cortical
screw and locking
screw

30. The locking screws, by
achieving angular stability
within the plate holes are
able to produce a similar
hoop with just two
unicorticalscrews.
LCP

31. LOCKING COMPRESSION PLATE (LCP) Principle :
Angular-stabilitywhereas
stabilityofconventional
platesisfrictionbetweenthe
plateandbone
Screwlockingprinciple
Providestherelativestability
Healingbycallusformation
(SecondaryHealing)

32. Stabilityunderload
•Bylockingthescrewstotheplate,
theaxialforceistransmittedover
thelengthoftheplate
•secondary lossof the
intraoperativereductionisreduced
Bloodsupplytothebone
•Noadditionalcompressionafter
locking
•Periostealbloodsupplywillbe
preserved

33. LCP used as internal fixatorto
bridge multifragmentary
diaphysealfracture zone.
Locking compression plate is
used.
Standard cortical and
cancellousscrews are used as
a traditional plate.
LCP

34. Principle of internal fixation using
LCP :
1.1
st
reducedthe#asanatomicalaspossible
2.Corticalscrewshouldbeused1
st
inafracture
fragment
3.Ifthelockingscrewhavebeenput,useofthe
corticalscrewinthesamefragmentwithout
looseningandretighteningofthelockingscrewis
notrecommended
4.Iflockingscrewisusedfirstavoidspinningofplate
5.Unicorticalscrewscausesnolossofstability

35. 6.InOsteoporoticbonebicorticalscrews
shouldbeused.
7.Incomminuted#screwholesclosetothe
fractureshouldbeusedtoreducestrain.
8.Inthefracturewithsmallornogapthe
immediatescrewholesshouldbeleft
unfilledtoreducedthestrain.
Principle of internal fixation
using LCP :

36. Indications :
1.Osteoporotic#
2.Periprosthetic#
3.Multifragmentry#
4.Delayedchangefromexternalfixationtointernal
fixation.

37. Advantages :
1.Angularstability
2.Axialstability
3.Platecontouringnotrequired
4.Lessdamagetothebloodsupplyofbone
5.Decreaseinfectionbecauseof
submusculartechnique
6.Lesssofttissuedamage

38. Sizes of DCP
Name of plate Small Narrow Broad
Width 11 mm 13.5 mm 17.5mm
Profile 4 mm 5.4 mm 5.4 mm
Screw 2.7 , 3.5 cortex screw and
4 mm cancellousscrew
4.5 mm cortex screw &
6.5mm canellousscrew
4.5 mm cortex screw &
6.5mm canellousscrew
Sizes of LCDCP
Name of plate Small Narrow Broad
Width 11 mm 13.5 mm 17.5mm
Profile 4 mm 5.4 mm 5.4 mm
Screw 2.7 , 3.5 and 4 mm
cancellous screw
4.5 mm & 6.5mm
canellous screw
4.5 mm & 6.5mm
canellous screw
Name of plate Small Narrow Broad
Width 11 mm 13.5 mm 17.5mm
Profile 4 mm 5.0 mm 5.0 mm
Screw 4 mm locking screw5 mm locking screw 5 mm locking screw
Sizes of LCP

40. LISS System
Preshapedplates with self
drilling self tapping screws
with threaded heads.
Through a small incision
(using this jig ) plate is slid
along the bone surface.
position of plate and wire
are checked radiologically
before insertion of
metaphysealscrew .

41. LISS-Less Invasive Stabilization
System

42. LISS

44. Type of plate –Functional
Regardlessoftheirlength,thickness,
geometry,configurationandtypesofhole,all
platesmaybeclassifiedinto4groups
accordingtotheirfunction.
1.Neutralizationplate.
2.Compressionplates.
3.Buttressplate.
4.Tensionbandplates.

45. NEUTRALIZATION PLATE
•Actsasa""bridge””protection
•Nocompressionatthefracturesite
•neutralizationplateistoprotectthe
screwfixationof
•ashortobliquefracture
•abutterflyfragment
•amildlycomminutedfractureofa
longbone
•fixationofasegmentalbonedefectin
combinationwithbonegrafting.

46. The Neutralization Plate
Lag screws:
compression and
initial stability
Plate:
protects the screws
from bending and
torsional loads

47. NEUTRALIZATION PLATE

48. COMPRESSION PLATE
•producesalocking
forceacrossafracture
site
•plateisattachedtoa
bonefragmentthen
pulledacrossthe
fracturesite ,
producingtensionin
theplate
•Directionofthe

49. Compression Plate
Principle:
-a self compression
plate due to the
special geometry
of screw holes
which allow the
axial compression.

50. Dynamiccompressionprinciple:
aTheholesoftheplateareshapedlikeaninclinedandtransversecylinder.
b–cLikeaball,thescrewheadslidesdowntheinclinedcylinder.
d–eDuetotheshapeoftheplatehole,theplateisbeingmovedhorizontallywhenthescrewis
drivenhome.
fThehorizontalmovementofthehead,asitimpactsagainsttheangledsideofthehole,resultsin
movementoftheplateandthefracturefragmentalreadyattachedtotheplatebythefirstscrew(1).
Thisleadstocompressionofthefracture.

51. 51
Compression plate:
eccentric DC (dynamic
compression) hole
Removable device:
compression device
Interfragmentarycompression by plate

52. 52
External compression device

53. METHODS OF ACHIEVING COMPRESSION
Withtensiondevise
Byoverbending
Withdynamiccompressionprinciple(DCP/LC-
DCP)
Bycontouringplate
Additionallagscrewthroplate

54. BUTTRESS PLATE
•istostrengthen(buttress)a
weakenedareaofcortex
•Theplatepreventsthebone
fromcollapsingduringthe
healingprocess.
•Abuttressplateappliedaforce
tothebonewhichis
perpendicular(normal)tothe
flatsurfaceoftheplate.

55. •Thefixationtotheboneshould
begininthemiddleoftheplate,
closesttothefracturesiteon
theshaft.Thescrewsshould
thenbeappliedinanorderly
fashion,oneaftertheother,
towardsbothendsoftheplate.
example:theT-plateused
forthefixationoffracturesof
thedistalradiusandthetibial
plateau.
BUTTRESS PLATE

56. Bridge Plating
Bridge Plating for
comminuted fracture
-instead of individually fixing each
fragment
-minimal disruption to blood supply
-reduction is performed indirectly
-compression is only sometimes
possible

57. TENSION BAND PRINCIPLE
Tension-band principle.

58. TensionBandPrinciple:-
Itsdescribeshowthetensileforcesare
convertedintocompressiveforcesbyapplyinga
deviseeccentricallyortotheconvexsideofa
curvedtubeorbone.
Indications:-
FracturePatella,olecranon,medialmalleolus,
greatertrochanterofthefemur.
Static
Dynamic

59. Dynamic and static tension band
In dynamic tension band the
tensile forces are converted to
compression on the convex side
of an eccentrically loaded bone
Examples :
Patella
Olecranon
Greater tuberosity
Tension band principle to the
medial malleolus example of
static tension band

60. HOW MANY SCREWS ?
Bones No. of CorticesNo. of Holes Type of
Plate
Forearm5to6Cortex6holes Small3.5
Humerus7to8Cortex8holes Narrow4.5
Tibia 7to8Cortex7holes Narrow4.5
Femur 7to8Cortex8holes Narrow4.5
Clavicle5to6Cortex6holes` Small3.5

61. TimingofPlateRemoval
Malleolar fractures. 8-12mo
The tibial pilon. 12-18mo
The tibial shaft. 12-18mo
The tibial plateau. 12-18mo
Thefemoralcondyles.12-24mo
Thefemoralshaft. 24-36mo
Upperextremity. 12-18mo
Shaftofradius/ulna. 24-28mo
Distalradius. 8-12mo
Metacarpals. 4-6mo

62. SCREW: INTRODUCTION
An elementary machine to change the small
applied rotational force into a large
compression force
Function
Holds the plate or other prosthesis to the bone
Fixes the # fragments ( Position screw)
Achieves compression between the # fragments
(Lag screw)

63. SCREWS
4 functional parts
Head
Shaft\Shank \Core
Thread
Tip

64. Head: Recess Types
1. Slotted
2. Cruciate
3. Philips
4. Hex/ Allen
5. Torx(egStardriveof Synthes)

65. Screw: Shaft/ Shank/Core
Smooth link
Almost not present in standard cortex screw
Present in cortical SHAFT SCREW or
cancellousscrew

66. Screw: Run out
Transition between shaft and thread
Site of most stress riser
Screw break
Incorrectly centered hole
Hole not perpendicular to the plate

67. Screw: Thread
Inclined plane encircling the root
Single thread
May have two or more sets of threads
V-thread profile: more stress at sharp corner
Buttress thread profile: less stress at the
rounded corner

68. Core
Solid section from which the threads project
out wards. The size of core determines the
strength of screw and its fatigue resistance.
The size of drill bit used is equal to the core
diameter.

69. Screw: Core Diameter
Narrowest diameter across
the base of threads
Also the weakest part
Smaller root shear off
Torsionalstrength varies
with the cube of its root
diameter

70. Screw: Thread Diameter
Diameter across the
maximum thread
width
Affects the pull out
strength
Cancellous have
larger thread
diameter

71. Screw: Tip Designs
1. Self-tapping tip:
Flute
Cuts threads in the bone over which screw
advances
Cutting flutes chisel into the bone and direct
the cut chips away from the root

72. Screw: 2.Non self tapping
Lacks flutes
Rounded tip
Must be pre-cut in the pilot hole by tap
Pre-tapped threads help to achieve greater
effective torque and thus higher inter-
fragmental compression
Better purchase

73. Screw: 3.Corkscrew tip
Thread forming tips
In Cancellous screws which
form own threads by
compressing the thin walled
trabecular bone
Inadequate for cortical bone

74. Screw: 4.Trochar Tip
Like self tapping
Displaces the bone as it advances
Malleolarscrew
Schanzscrews
Locking bolts for IMIL

75. Screw: 5.Self drilling self
tapping
Like a drill bit
In locked internal
fixatorplate hole
Pre-drilling not
required
Flute
Good purchase in
osteoporotic and
metaphysealarea

76. Locking Screws vs Cortical
Screws
Creates Fixed Angle
Generates
Friction/Compression
4.4mm Core Dia. 3.5mm Core Dia.
5.0 mm Locking Screw 4.5 mm Cortical Screw

77. Bending stiffness proportional to the core
diameter
Pull out strength is proportional to the size of
the thread
Cannulated screws have less bending
stiffness

78. AO/ASIF Screws: Types
Cortical
Fully threaded
Shaft screw
1.5:phalanx *drill bit 1.1 mm
2.7: mc and phalanx *bit:2.0
3.5: Radius/ Ulna/ Fibula/ Clavicle*bit:2.5
4.5: Humerus/ Tibia/ femur *bit:3.2

79. AO/ASIF Screws
•Cortical screws:
–a machine type
–Smaller threads
–Lower pitch
–Large core diameter
–Smaller pitch higher holding
power
–greater surface area of
exposed thread for any
given length
–better hold in cortical bone

80. AO/ASIF Screws
•Cancellousscrews:
–a wood type
–core diameter is less
–the large threads
–Higher pitch
–Greater surface are for purchase
–Untapedpilot hole
–Pilot hole equals the core diameter
–lag effect option with partially threaded screws
–theoretically allows better fixation in soft
cancellousbone.

81. Cancellous
Fully threaded
Cannulatedor Non-cannulated
Partially threaded
16mm or 32 mm
Cannulatedor Non-cannulated
4.0,drill bit 2.5mm humeral condyle
6.5drill bit 3.2mm tibialand femoral
condyle

82. MALLEOLAR SCREW:
-smooth shaft
-partially threaded
-trephine tip : no tapping needed
-was designed as lag screw for malleoli
fixation NOW small cancellous screws
preffered
-distal humerus and
lesser trochanter
-size : 25mm –75 mm

83. Cannulated screws
3.0
4.0
4.5
6.5
7.0
7.3

84. Special Screws
Locking bolt
Herbert Screw
Dynamic Hip
Screw
MalleolarScrew
Interference
screw
Acutrakscrew

85. Pedicle screw
Suture anchor

86. Headless Screws
Herbert screw bridging
a scaphoidfracture
Acutrakscrew

87. BioabsorbableScrews
The most common
materials used are
polylacticacid
(PLA), poly-L-
lactic acid (PLLA),
and polyglycolic
acid.

88. Advantagesof bioabsorbable
screws
• Does not interfere with MRI.
• Does not interfere with future revision
surgery if needed.
• Decreased incidence of graft laceration.
• Does not need implant removal

89. Disadvantagesof
bioabsorbablescrews
• Major disadvantage is screw failure during
insertion. Special screw drivers that span the
entire length of screw reduce incidence of
screw breakage.
• Foreign body reaction may be seen in some.

90. Function or mechanism.
Neutralization screws–neutralizes forces on the
plate in plate fixation.
Lag screws –For inter-fragmentary compression.
Reduction screw –To reduce displaced fracture by
pushing or pulling.
Position screw–Holds two fragments in position
without compression. Eq. Syndesmoticscrew
Anchor screw–Acts as an anchor for wire or
suture. In tension band wiring
Locking head screw–In locking plates
Locking screw–In interlocking nails
Poller screw–To guide the nail path in
interlocking nailing of fractures close to the bone
ends.

91. TAP
To cut threads in bone of same size as the screw
to facilitate insertion
Flutes : to clear the bone debris
Two turns forward and half turn backward
recommended to clear debris
Used with sleeve
Done manually
Power tapping NOT recommended
For cancellousbone : short and wide thread ,
slightly smaller diathan screw

92. For cortical screws :
-as fixation screw : both cortices
-as lag screw : only far cortex
For cancellousscrew:
-only near cortex
-sometimes in young patients tapping entire
screw length needed

93. LAG SCREW TECHNIQUE :
-to achieve interfragmentarycompression
-this technique is used if a screw is to be
inserted across a #, even through a plate.
-screw has no purchase in near fragment,
thread grips the far fragment only
-achieved either with screw with shaft or
fully threaded screw

94. Positioning of screws:
-max. interfragmentarycompression :
placed in middle of fragment,
right angle to fracture plane
-max. axial stability: right angle to long
axis of bone

96. Thank You