Pw-lecture Orthopaedic Surgery Schulz

8/7/2019 Pw-lecture Orthopaedic Surgery Schulz

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Modern Implants in orthopaedic TraumaModern Implants in orthopaedic Trauma

Arndt P Schulz, MD, MRCS (Glasgow)Arndt P Schulz, MD, MRCS (Glasgow)

University Hospital LUniversity Hospital Lbeck, Dept Trauma and Orthopaedicsbeck, Dept Trauma and Orthopaedics

Klaus Seide, MD, PhDKlaus Seide, MD, PhD

BG Trauma Hospital Hamburg, Biomechanical LaboratoryBG Trauma Hospital Hamburg, Biomechanical Laboratory

Masters Programme

Biomedical Engineering


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Orthopedic surgeons have aOrthopedic surgeons have abroad variety of implantsbroad variety of implants

for external and internalfor external and internalstabilisation of fracturesstabilisation of fractures

and luxationsand luxations


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External fixatorExternal fixator

ImplantsImplants

(e.g for the distal femur)(e.g for the distal femur)


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ScrewsScrews

Implants

(e.g for the distal femur)


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patient, female, 37 y.:patient, female, 37 y.: distal femoral fracture type B2distal femoral fracture type B2

caused by a fall down the stairs ; treated with 3 screwscaused by a fall down the stairs ; treated with 3 screws


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ImplantsImplants(e.g for the distal femur)(e.g for the distal femur)

Conventional plate systems:Conventional plate systems:

Condylar plate (so

called Burri-plate)

95 angular blade plate

Dynamic condylar screw(DCS)


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patient female 60 y.:patient female 60 y.: distal femoral fracturedistal femoral fracture

type A1 caused by a simple fall due to osteoporosis;type A1 caused by a simple fall due to osteoporosis;

treated with a DCStreated with a DCS


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IntramedullarIntramedullarnailsnails

ImplantsImplants



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patient, male, 40 y.:patient, male, 40 y.:A1 distal femoral fracture typeA1 distal femoral fracture type

A1 caused by a car accident ; treated with anA1 caused by a car accident ; treated with an

intramedullary nailintramedullary nail


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Angular stable internal fixators withAngular stable internal fixators with

locked screwslocked screws

ImplantsImplants



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patient, female, 18 y.:patient, female, 18 y.: distal femoral fracture typedistal femoral fracture type

C3 caused by a car accident ; treated with an angular stableC3 caused by a car accident ; treated with an angular stable

internal fixatorinternal fixator


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.and now let.and now lets have as have a

closer look on internalcloser look on internal

fixators or implants withfixators or implants withlocked screws or angularlocked screws or angular

stable implantsstable implants


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How to defineHow to define

angular stability ?angular stability ?

strong, longlasting butstrong, longlasting but

reversible union ofreversible union ofscrews and longitudinalscrews and longitudinal

stabilisator (plate, nailstabilisator (plate, nail

or external fixator rod)or external fixator rod)

(Wolter 1985)(Wolter 1985)


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Biomechanical principle IBiomechanical principle I

conventional plateconventional plate--

osteosynthesisosteosynthesisinternal plate fixatorinternal plate fixator

Seide et al. 1999


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Biomechanical principle IIBiomechanical principle II

conventionalconventionalplateplate--

osteosynthesisosteosynthesis

internal plateinternal plate

fixatorfixator


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Why do we need internal fixators?Why do we need internal fixators?

1.1. Higher and first of allHigher and first of alllongerlasting stability.longerlasting stability.

2.2. More independence fromMore independence frombone quality than inbone quality than inconventional plating.conventional plating.

3.3. Biological reasons. TheBiological reasons. Theblood supply of the boneblood supply of the boneby the periostium is lessby the periostium is lessdisturbed due to adisturbed due to adiminished pressure ondiminished pressure onthe bone by the plate.the bone by the plate.


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Different ImplantsDifferent ImplantsLess invasive stabilisation System (LISS)Less invasive stabilisation System (LISS)

Unidirectional,monocortical screws


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Multidirectional internal plate fixatorsMultidirectional internal plate fixatorsPressurePressure--PlatePlate--FixatorFixator

(PPF)(PPF) Titanium Internal-Fixateur (TiFix)

cervical, thoracical

and lumbar spine

femur

1st generation; distal

femur, tibia

2nd generation;the rest of thebody


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First Solution in 1931 by DrFirst Solution in 1931 by Dr

Reinhold/ ParisReinhold/ Paris


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First modern solution to produce anFirst modern solution to produce an

angular stable screwangular stable screw--plate interfaceplate interfaceMultidirectional internal fixator for the thoracic andMultidirectional internal fixator for the thoracic and

lumbar spine 1985lumbar spine 1985 -- Pressure plate principlePressure plate principle

Angular stability by locking the head ofAngular stability by locking the head ofthe screw in the plate hole withthe screw in the plate hole with

Stabilisation of a fracture of theStabilisation of a fracture of the


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Stabilisation of a fracture of theStabilisation of a fracture of the

1. lumbar vertebral body by a PPF1. lumbar vertebral body by a PPF

PressurePressure-PlatePlate-Fixator (PPF)Fixator (PPF)


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PressurePressure--PlatePlate--Fixator (PPF)Fixator (PPF)

for the femurfor the femur

`83 `85


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First patient

treated with aPPF*1941injured in 1983

83 85

`87 `93


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Bony consolidation inBony consolidation in

9/19939/1993


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l h


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Minimal invasive osteosynthesisMinimal invasive osteosynthesis

of the femur by a PPFof the femur by a PPF


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Plate:Plate: softersofter Material (e.g. titanium grade 1 )Material (e.g. titanium grade 1 )

Screw:Screw: harderharder material (e.g. titanium grade 4material (e.g. titanium grade 4or 5, titanium alloy) 1992or 5, titanium alloy) 1992

Angular stability by material reshapingAngular stability by material reshaping

Second solution to produce aSecond solution to produce a

locked screwlocked screw--plate interfaceplate interface


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TiFix 1TiFix 1stst GenerationGeneration

Thread-miller


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TiFix 1TiFix 1stst generationgeneration

The angleThe anglebetween screwbetween screw

and plate can beand plate can be

choosen freely upchoosen freely upto 45to 45 to eachto each

direction !direction !

TiFix 2TiFix 2ndnd GenerationGeneration


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TiFix 2TiFix 2ndnd GenerationGeneration

liplip--constructionconstruction

No threadNo thread--millermiller

needed!needed!

History of the development of multiHistory of the development of multi--


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History of the development of multiHistory of the development of multi

directional internal plate fixatorsdirectional internal plate fixators1985 PPF lumbar an1985 PPF lumbar and thoracicd thoracic

spinespine1991 PPF cervical spine1993 PPF femur

1997 TiFix tibia1998 TiFix calcaneus and

distal femur1999 TiFix humeral head,

forearm and tibial head


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First problemFirst problem

d bl


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Second problemSecond problem


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Solution?Solution?

Unilateral osteosynthesis ofUnilateral osteosynthesis of

tibial head by angular stabletibial head by angular stable

butress platebutress plate


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Biomechanical Study designBiomechanical Study design

Comparison of unilateral osteosynthesis of tibialComparison of unilateral osteosynthesis of tibial

head fractures by butress plate in angular stablehead fractures by butress plate in angular stable

and conventional technique in fresh humanand conventional technique in fresh humancadaveric tibial heads by biomechanical testing oncadaveric tibial heads by biomechanical testing on

a servohydraulic material test machine.a servohydraulic material test machine.

The technique of plating (angular stable orThe technique of plating (angular stable or

conventional) was the only variable.conventional) was the only variable.

M t i lM t i l


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MaterialMaterial

5 paarige humane Tibiakopfpr5 paarige humane Tibiakopfprparate aufparate auf45mm gek45mm gekrzt.rzt.

5 paired fresh human cadaveric tibialheads cut down to a length of 45millimeters

Measurement of bone densityMeasurement of bone density


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Measurement of bone densityMeasurement of bone density

by computer tomographyby computer tomography

European spine

phantom


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M t i l t ti hiM t i l t ti hi


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Material testing machineMaterial testing machine

Biaxial, servohydraulicBiaxial, servohydraulic

material testingmaterial testingmachine MTS Typmachine MTS Typ

Bionix 858.2Bionix 858.2

St d di d tiStandardized preparation


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Standardized preparationStandardized preparation

XX t ll d t th it ll d t th i


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XX--ray controlled osteosynthesisray controlled osteosynthesis

Testing assemblyTesting assembly


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Testing assemblyTesting assembly

Tibial head

Femoral partof a knee

prothesis

LVDT

plate

LVDT

link joint

X-Y-table

Testing protocolTesting protocol


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Testing protocolTesting protocol

preload 10Npreload 10N

sinus shaped, cyclic, forcesinus shaped, cyclic, force--induced load,induced load,frequence 4 Hzfrequence 4 Hz

initial axial load 100 Ninitial axial load 100 N increase of load by 50 N every 2000increase of load by 50 N every 2000

cycles until failure of the construct or 700 Ncycles until failure of the construct or 700 Nareare reached (maximum 26000 cycles)reached (maximum 26000 cycles)

ResultsResults II


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ResultsResults II

failurefailure (at load in N )(at load in N )numbernumber bone densitybone density

(mg HA/cm(mg HA/cm)) angular stableangular stable conventionalconventional11 146.8146.8 600600 350350

22 63.163.1 >700>700 300300

33 78.178.1 550550 20020044 60.460.4 600600 400400

55 118.7118.7 650650 450450

medianmedian 600600 350350

minmin 550550 200200

maxmax >700>700 450450

Results IIResults II


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Results IIResults IIvarus motion at 100Nvarus motion at 100N (mm)(mm) offset at 100Noffset at 100N (mm)(mm)numbernumber

angular stableangular stable conventionalconventional angular stableangular stable conventionalconventional

11 0.1130.113 0.1390.139 0.4440.444 0.4240.42422 0.0030.003 0.0870.087 0.2690.269 0.4250.425

33 0.1460.146 0.6310.631 0.3310.331 1.2071.207

44 0.2530.253 0.2690.269 0.2940.294 0.2680.26855 0.060.06 0.1390.139 0.2010.201 0.3500.350

medianmedian 0.1130.113 0.1390.139 0.2940.294 0.4240.424

minmin 0.0030.003 0.0870.087 0.2010.201 0.2680.268

maxmax 0.2530.253 0.6310.631 0.4440.444 1.2071.207

SummarySummary


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SummarySummary

The angular stable construct showed in

every single test a significant higherstability in comparison to the conventionalconstruct (p < 0,05)

The increase of stability concerning varus

motion and offset reached up to 500%.

A loosening of the angular stable screw-plate interface was seen in no case

And in the FutureAnd in the Future ??


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And in the FutureAnd in the Future??

Routine Load Measurements ininternal Fixator Systems

Monitoring of Fracture Healing

Optimisation of postoperative Treatment

Concept


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Locked Implant

DMS Sensors

Microelektronic/Telemetry

Encapsulation

Concept

Telemetry


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Telemetry

RF-Interface

C basedcontrol unit

Energy

Data

Disla

ApplicationPC with custom-designed

software

C basedtransponder

Readout circuit

Sensor

Pow

er

Readercoil

Transpondercoil

External Electronics Implantable System

Transponder with Sensor Interface


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Transponder with Sensor-Interface

Implants for Tibia and Femur


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Implants for Tibia and Femur

Readout


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Readout

Biomechanic in vitro testing


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Biomechanic in vitro testing

Biegung senkrecht zur Plattenebene

unter simulierten Frakturbedingungen

-300

-200

-100

0

100

200

300

0 100 200 300 400 500 600 700 800 900

Newton

V/V

F4

F5

F6

F7

F8

F9

F10

F11

F12

F13

F14F15

F16

F17

F18

F19

F20

F21

F22

F23

F24

F25

E1

E5

E6

In-vivo testing in sheep


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In-vivo testing in sheep


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Korrelation Fixateurbelastung vs. Kraft

(8 Kraftzyklen)y = 2,4677x + 35,171

R2

= 0,9532

Steifigkeit: 0,41 N/(m/m)

0,0

25,0

50,0

75,0

100,0

125,0

150,0

175,0

200,0

0,0 5,0 10,0 15,0 20,0 25,0 30,0 35,0 40,0 45,0 50,0

Externe Kraft [N]

F

ixateurbelastung(Dehn

ung[m/m]

Bluetooth-Readout


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Bluetooth Readout

In-vivo use in Patients


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In vivo use in Patients


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Patient 2, 11.08.05, postop

0,0

100,0

200,0

300,0

400,0

500,0

600,0

0,000 50,000 100,000 150,000 200,000

Time [s]

Measured

data

Kraft [N] Fixateur (A/D Code [dez])

Physiotherapy


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Implantat-Biegebelastung bei KG-bungen

0%

100%

200%

300%

400%

500%

600%

Implantatbelastung unter 10kgaxial

max. Anspannung der OS-Muskulatur

Anheben des Beines inRckenlage

KG-bungen mitTorsionskomponente

Prozent

ys ot e apy

Outlook


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Routine Use

Telemedical Patient Supervision

Optimisation of postop. treatment regime

Future of External Fixation ?


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First external fixator(Wutzer, 1843)

Electronically Controlled (Electronically Controlled (IntelligentIntelligent))

External Fixator SystemsExternal Fixator Systems


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Measurement of fracture healingprogress

Detecting delayed healing orpseudarthrosis formation

Controlling patient activity bydisplay or voice

Actively controlling optimal load onthe fracture gap (Dynamisation)

Actively performing fracturereduction

y

Control

Unit

Force Sensors

Linear

Motors

Motor Driven FixatorMotor Driven Fixator


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R.L.08/2003



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R.L.08/2003

33--Dimensional Load MeasurementsDimensional Load Measurements


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Fground

fixator

callus

bone

Fground

fixator

callus

bone

0

5

10

15

20

25

30

2 4 8 12

Mxy(Nmm/N)

0

5

10

15

20

25

30

2 4 8 12

time ( weeks )

Mxy(Nmm/N)

0

5

10

15

20

25

30

2 4 8 12 MZeit (Wochen)

Mxy(Nmm/N)

5 A2

6 A27 A2

8 B2

9 C3

0

5

10

15

20

25

30

2 4 8 12 MZeit (Wochen)

Mxy(Nmm/N)

1 A3

2 A3

3 A3

4 A3

Patient A: delayedfracture healing

Patient B: normalfracture healing

SummarySummary Universal and precise 3Universal and precise 3--dimensional bone movementsdimensional bone movements


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Universal and precise 3Universal and precise 3 dimensional bone movementsdimensional bone movements

Path of reduction / correction can be modified at any timePath of reduction / correction can be modified at any time

To be applied with different fixator systemsTo be applied with different fixator systems

Painless fracture reductionPainless fracture reduction

Motors and measurement additions possible (Motors and measurement additions possible (Intelligent FixatorIntelligent Fixator))

Very helpful addition to the treatment optionsVery helpful addition to the treatment options


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Thank You!Thank You!

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Pw-lecture Orthopaedic Surgery Schulz