the charnley kerboull hip system results of a 30 years experience in cemented fixation l kerboull, m...

The Charnley Kerboull hip systemThe Charnley Kerboull hip system

Results of a 30 years experienceResults of a 30 years experience in cemented fixationin cemented fixation

L Kerboull, M Kerboull.L Kerboull, M Kerboull.

Marcel Kerboull InstituteMarcel Kerboull Institute

Imk-forum.comImk-forum.com

introductionintroduction

• basis of the mechanical principles of the basis of the mechanical principles of the cemented fixation cemented fixation

• Current ControversiesCurrent Controversies• Subsidence and collarSubsidence and collar• Surface finishSurface finish• Cementing technique and cement thicknessCementing technique and cement thickness• Classification of cemented stemClassification of cemented stem

• What must be a perfect cemented stem What must be a perfect cemented stem

• Clinical Results to support our theoryClinical Results to support our theory

The original charnley stem : the golden The original charnley stem : the golden standardstandard

8 % of stem debonding8 % of stem debonding– radiolucent line between cement radiolucent line between cement and stem in zone 1 of Amstutzand stem in zone 1 of Amstutz

– cement mantle crack cement mantle crack at the stem tip levelat the stem tip level

even so often asymptomatic, even so often asymptomatic, it was for us. it was for us. a failure of the primary stem fixationa failure of the primary stem fixation

Introduction : Current optionsIntroduction : Current options

• Modern Cementing technique and cement Modern Cementing technique and cement mantle minimal thickness were identified as mantle minimal thickness were identified as solutions to address the problem of femoral solutions to address the problem of femoral stem loosening.stem loosening.

• Our mechanical theory of the cemented fixation Our mechanical theory of the cemented fixation was initiated in 1972 and is very differentwas initiated in 1972 and is very different

Taper slip VS Composite beam

Taper-slip system

CMK

Exeter Flanged Charnley

Harris Precoat

Composite-beam system

CPT, C-stem

?

Mechanical basis Mechanical basis of stem cemented fixationof stem cemented fixation

Bone, cement and stem make Bone, cement and stem make a composite structurea composite structure- All mentioned materials have different E-Moduli- All mentioned materials have different E-Moduli

Cortex:Cortex: 12 - 18 Gpa 12 - 18 GpaPMMA:PMMA: 1.8 Gpa 1.8 GpaWHN Stainless SteelWHN Stainless Steel 250 Gpa250 Gpa

- Each of these materials had different strains under cyclic axial - Each of these materials had different strains under cyclic axial and torsional load that induce micromotion at the interfacesand torsional load that induce micromotion at the interfaces

- Micromotion primary occurs at the stem-cement interfaceMicromotion primary occurs at the stem-cement interface

- Micromotion can only be partially absorbed by cement Micromotion can only be partially absorbed by cement elasticityelasticity

- Micromotion is settled by the stem which is the stiffest Micromotion is settled by the stem which is the stiffest component component

MechanicalMechanical basis basis of stem cemented fixationof stem cemented fixation

The mechanical stability The mechanical stability

of this composite of this composite

Is depending on the mechanical properties Is depending on the mechanical properties and shape of the 3 componentsand shape of the 3 components

But the most rigid component will always But the most rigid component will always have the most positive or negative influencehave the most positive or negative influence

How to improve stem cemented fixationHow to improve stem cemented fixation

1.1. Improve mechanical properties of cement Improve mechanical properties of cement 2.2. Increase cement layer thicknessIncrease cement layer thickness3.3. Improve cementing technique Improve cementing technique 4.4. Improve bone-cement interfaceImprove bone-cement interface5.5. Modify stem design to decrease stresses Modify stem design to decrease stresses

supported by cement supported by cement 6.6. Look for a secondary fixation through a Look for a secondary fixation through a

distal migration : subsidencedistal migration : subsidence7.7. Increase link between stem and cement Increase link between stem and cement

through a rough surfacethrough a rough surface

Solutions :Solutions :

1 Improve mechanical properties of cement ?1 Improve mechanical properties of cement ?

Cement is a viscoelastic brittle material Cement is a viscoelastic brittle material characterized by relatively high characterized by relatively high

compressive strength resistance but compressive strength resistance but weakness in tension and bendingweakness in tension and bending

Acrylic bone cements: mechanical and physical Acrylic bone cements: mechanical and physical propertiesproperties

Orthop Clin North Am 2005; 36: 29-39Orthop Clin North Am 2005; 36: 29-39Kuehn KD and collKuehn KD and coll

Compressive strengthCompressive strength 90 Mpa90 Mpa

Shear strengthShear strength 50 Mpa50 Mpa

Tensile strengthTensile strength 25 Mpa25 Mpa

Improve mechanical properties of cement ?Improve mechanical properties of cement ?

« initial migration seems to be independent of « initial migration seems to be independent of the type of cement and of its viscosity »the type of cement and of its viscosity »

The influence of cement viscosity on early migration of The influence of cement viscosity on early migration of a tapered polished femoral stema tapered polished femoral stem

Glyn-Jones and collGlyn-Jones and collInt Orthop 2003 ; 27: 362-5Int Orthop 2003 ; 27: 362-5

In fact, cement was, is and will ever beIn fact, cement was, is and will ever be the weakest component of this composite the weakest component of this composite

structurestructure

2 Increase cement layer thickness ?2 Increase cement layer thickness ?

Wide medullary canalWide medullary canalThick cementThick cementDebonding 36 %Debonding 36 %

We found the answer to this We found the answer to this questionquestionfrom the observation of our from the observation of our Charnley first casesCharnley first cases


Narrow canalNarrow canalThin cement Thin cement Debonding 6 %Debonding 6 %


Dysplastic femurDysplastic femurVery Thin cement Very Thin cement

Debonding 0 %Debonding 0 %

25 y

2 Thickening cement layer was not for 2 Thickening cement layer was not for us the best choiceus the best choice

• this observation suggested that a stem fitted to cortical this observation suggested that a stem fitted to cortical bone with a thin cement layer might improve the bone with a thin cement layer might improve the cemented fixationcemented fixation

• It was also evident that an undersized stem used to get a It was also evident that an undersized stem used to get a thick cement mantle was not the good solution to prevent thick cement mantle was not the good solution to prevent distal migration, because even thicker the cement was distal migration, because even thicker the cement was not enough resistant to face the stresses transmitted by not enough resistant to face the stresses transmitted by the stem.the stem.

« initial migration seems to be independent of the thickness « initial migration seems to be independent of the thickness of the cement mantle »of the cement mantle »

Influence of cement viscosity and cement mantle thickness Influence of cement viscosity and cement mantle thickness on migration of the Exceter total hip prosthesison migration of the Exceter total hip prosthesis

Nelissen RG and collNelissen RG and coll

J Arthroplasty 2005;20:521-8J Arthroplasty 2005;20:521-8


1.1. Improve mechanical properties of cement Improve mechanical properties of cement 2.2. Increase cement layer thicknessIncrease cement layer thickness3.3. Improve cementing technique Improve cementing technique 4.4. Modify stem design to decrease stresses Modify stem design to decrease stresses

supported by cement supported by cement 5.5. Improve bone-cement interfaceImprove bone-cement interface6.6. Look for a secondary fixation through a Look for a secondary fixation through a




3 Improve cementing technique ? 3 Improve cementing technique ?

• Why :– To increase resistance of cement to bone interface through a

deep penetration of cement to create interdigitation

– To get an homogeneous and more resistant cement mantle

At least 3 mm

3 Improve cement and cementing technique ? 3 Improve cement and cementing technique ?

• How ? :– Low viscosity cement– Vacuum preparation to avoid

air– High Pressure water cleaning– High pressure cement insertion– Stem tip centralizer– undersized stem


What can we expect from these techniques ?

- Prevent early distal migration ? Definitely no- Prevent late loosening

- No influence for the shaped closed fixation, like CMK- May be for the loaded-taper fixation, like Exceter- But

- with a time consuming, aggressive for the bone and demanding technique

- With an important increase of the overall price of the proceedure


Plugging and simple washing of the medullary canal

Use of a Standard viscoelasticity cement

Simple Cement insertion using a syringe

High Pressure is applied by the canal filling stem

So for us Cementing technique is not a main issue And must remain a friendly and simple technique

Our current routine technique

4 Improve bone-cement interface4 Improve bone-cement interface

Bone is twin : cortice and cancellousBone is twin : cortice and cancellous

Does cancellous bone is able to carry the load ?Does cancellous bone is able to carry the load ?NO : Ebramzabeh E and coll : the cement mantle in total hip arthroplasty : NO : Ebramzabeh E and coll : the cement mantle in total hip arthroplasty :

analysis of long term radiographic resultsanalysis of long term radiographic resultsJBJS 1994 76-A,77-87JBJS 1994 76-A,77-87

Effect of aging: Effect of aging: lowering of mechnical properties of cancellous bonelowering of mechnical properties of cancellous bone

Are Interdigitations between cement and cancellous bone necessary ?Are Interdigitations between cement and cancellous bone necessary ?

Yes if you use a force loaded stem that submit the cement to high tensile Yes if you use a force loaded stem that submit the cement to high tensile stressstress

No, if cement is only submitted to a low level of compressive stresses by a No, if cement is only submitted to a low level of compressive stresses by a canal filling stem cemented line to linecanal filling stem cemented line to line


• Further under loading and aging cancellous bone Further under loading and aging cancellous bone undergoes compression and becomes unevenundergoes compression and becomes uneven

• In this situation, the cement mantle is subjected In this situation, the cement mantle is subjected to bending and tensile stresses and will crack.to bending and tensile stresses and will crack.

• So, removing the cancellous in the superomedial So, removing the cancellous in the superomedial part of the metaphysis and in the distal canal part of the metaphysis and in the distal canal gives the cement an even and rigid base and gives the cement an even and rigid base and prevents its crack under bending stressprevents its crack under bending stress


FemorFemoralalReameReamerr

Modification of the bone bed Modification of the bone bed preparationpreparation

Less agressiveLess agressiveMore preciseMore precise

Instead of broachInstead of broach

Removal of cancellous bone Removal of cancellous bone which is not able to which is not able to carrycarry load with aging load with aging

Mechanical basis of the stem debondingMechanical basis of the stem debonding

High bending stresses in the supero medial High bending stresses in the supero medial part part break the cement mantlebreak the cement mantle

This ruptureThis rupturewidenswidens the proximal part the proximal part of the cement mantleof the cement mantledecreasesdecreases the shear stresses the shear stresses along the stemalong the stemincreasesincreases the vertical force on the distal cement the vertical force on the distal cement which breakes under tensile stress which breakes under tensile stress and finally and finally allowedallowed varus tilt varus tilt and subsidence of the stem and subsidence of the stem

Because it was for us the most logical way:Because it was for us the most logical way:

to decrease the level of stress within and at to decrease the level of stress within and at the cement stem and cement bone the cement stem and cement bone interfaces interfaces

to only subject the cement mantle to to only subject the cement mantle to compressive stressescompressive stresses

and consequently avoid the problems of and consequently avoid the problems of the cement layer thickness and resistancethe cement layer thickness and resistance

5 Modify stem design : WHY ?5 Modify stem design : WHY ?

Were retained from the Charnley stemWere retained from the Charnley stem

Polished surface Polished surface Ra 0.04 Ra 0.04 (1.6 (1.6 inch)inch)

CollarCollar

Rectangular cross sectionRectangular cross section

The cup designThe cup design

5 Modify stem design5 Modify stem design

Three main modifications of the stem Three main modifications of the stem designdesignresulted in the MK 1resulted in the MK 1

1.1. Opening the stem-neck angle to Opening the stem-neck angle to 130° instead of 125°130° instead of 125°

2.2. widening the proximal part of the widening the proximal part of the stemstem

3.3. Increasing the range of sizesIncreasing the range of sizes


CCD angle & equal neck length

Geometrical dependence of CCD and cement mantle pressure

M1 M2

M1 < M2

Force in the superomedial partis higher with a flater CCD angledue to bigger offset

Stem CCD angle and cement loadingStem CCD angle and cement loading


Opening the stem neck angle to 130°Opening the stem neck angle to 130°

to decrease the pressure on the supero medial and to decrease the pressure on the supero medial and infero lateral part of the cement mantleinfero lateral part of the cement mantle

• CCD angle

125° 130°

CharnleyCharnley KerboullKerboull


Widening and thickeningWidening and thickening the stem proximal part the stem proximal part

to give it a double tapered shapeto give it a double tapered shape

with a cross-section sufficently decreasingwith a cross-section sufficently decreasing

(taper angle > 5°) (taper angle > 5°)

so thatso that


Widening and thickeningWidening and thickening the stem proximal part the stem proximal part

–the shear stresses the shear stresses along the stem along the stem

would be would be progressively progressively transformed transformed

into their pressure into their pressure componentscomponents

–and the vertical distal and the vertical distal force force

would be would be dramatically reduceddramatically reduced


5 modify the stem design: A large range 5 modify the stem design: A large range of sizesof sizes

1 to reconstruct a normal architecture in every case 1 to reconstruct a normal architecture in every case (limb length and abductor muscles off-set).(limb length and abductor muscles off-set).

30

40

50

60

Offset 42.4 43.0 44.2 49.2 50.6 52.2 57.1 58.5 59.9

Neck Length 32 32 32 36 36 36 40 40 40

201 202 203 301 302 303 401 402 403

2 to get a self alignment of the stem with the 2 to get a self alignment of the stem with the femoral diaphysis axisfemoral diaphysis axis


“ in our study, line to line stem without distal centralizer were better aligned than undersized stems fitted with a centralizer”

T Scheerlinck and collCT analysis of defects of the cement mantleAnd alignment of the stemJBJS 88 B,1 19-25

A large range of sizesA large range of sizes

Symmetrical anatomy

33 to have between to have between stem and femoral canalstem and femoral canalthe best fitthe best fit

to reduce load transmitted to reduce load transmitted to ciment layer to ciment layer


Under these conditionsUnder these conditions

Cement mantle, cement bone Cement mantle, cement bone interface are no longer subjected interface are no longer subjected to shear stresses to shear stresses

and micromotion is reduced to a and micromotion is reduced to a level tolerated by creep of cementlevel tolerated by creep of cement

With this canal filling stem, the With this canal filling stem, the double tapered shape is acting to double tapered shape is acting to decrease the stresses on the decrease the stresses on the cement, but with an undersized cement, but with an undersized stem the distal force increases and stem the distal force increases and the stem subsidesthe stem subsides

How to choose the appropriate size regarding to the canal filling concept

• According to the preoperative planning

• Not the largest one that will impose to ream the cortices but

• The first size that get– self alignment– primary stability

Ant. Post.Ant. Post.

Relatively thick > 2 Relatively thick > 2 mmmm

Med. Lat. Med. Lat.

Thin or very thin < 1 Thin or very thin < 1 mmmm

How is the cement mantle thickness How is the cement mantle thickness around a CMK stemaround a CMK stem

unevenunevenBut never incompleteBut never incomplete

T Scheerlinck and collCT analysis of defects of the cement mantleAnd alignment of the stemJBJS 88 B,1 19-25

Uneven cement mantle but never incompleteUneven cement mantle but never incomplete

And protected of overloading by the stem designAnd protected of overloading by the stem design

How to improve the cemented stem How to improve the cemented stem fixation ?fixation ?

• If you consider subsidence as a positive event to lock the fixation of the stem in the cement mantle you will try to favourize it but you will need to reinforce the cement to lower the distal migration

• If you consider subsidence as a primary failure of the initial fixation you will try to protect cement of over loading to prevent distal migration and to protect the ciment the only possibility you have is to work on the stem design

Subsidence and collar ?Subsidence and collar ?

Is Subsidence a normal event ?Is Subsidence a normal event ? - probably - probably No forNo for the CMK which the CMK which is not designed to subside is not designed to subside

and does not subside.and does not subside.

« The French paradox »: Langlais, Ling, Kerboull, « The French paradox »: Langlais, Ling, Kerboull, Sedel. JBJS Br, 2003. Sedel. JBJS Br, 2003.

Why ??Why ?? - We choose the stem which best fills the medullary canal - We choose the stem which best fills the medullary canal there is no space for the stem to subside.there is no space for the stem to subside.- The stem does not subside due to the cohesion forces acting on - The stem does not subside due to the cohesion forces acting on

the two polished (cement/stem) surfaces and micromotion the two polished (cement/stem) surfaces and micromotion stays under its cement fracture levelstays under its cement fracture level

The collarThe collar may decrease the distal force applied to ciment plugmay decrease the distal force applied to ciment plugdoes not prevent migration if it occursdoes not prevent migration if it occursjust an intraoperative reference to set leg lengthjust an intraoperative reference to set leg length

Does CMK subsides ?Does CMK subsides ?

Long-Term Migration Using EBRA-FCA of Stems Cemented Line-to-Line According to the "French Paradox" PrinciplesHamadouche, Moussa; Kerboull Luc; Kerboull, MarcelORS 2008

The EBRA-FCA software is a validated method designed to assess migration of afemoral component through comparable pairs of radiographs. Accuracy has been reported to be better than ± 1.5 mm (95% percentile), with a specificity of100% and a sensitivity of 78% for the detection of migration of more than 1.0 mm, usingRSA as the gold standard

Does CMK subsides ?Does CMK subsides ?

Materials and Methods: In 1988 and 1989, 164 primary THA in 155 patients by the two seniors of us. mean age 63.8 ± 11.6 years. Polished CMK

Results: 73 patients (77 hips) still alive F.U 17.3 ± 0.8 years (15-18 years), 8 patients (8 hips revised for high polyethylene wear 66 patients (69hips) deceased8 patients (10 hips) lost to follow-up.

1689 radiographs (mean 10.3 per hip) were digitized. 263 (15.6%) excludedNo migration curve obtained for 22 of the 164 femoral components (13.4%).

Mean subsidence of the entire series was 0.63 ± 0.49 mm Using a 1.5 mm threshold for subsidence, 4 of the 142 stems have migrated. Using a threshold of 2 mm for subsidence, none of the 142 stems have migrated.

Does CMK subsides ? NODoes CMK subsides ? NO

this study demonstrates

that contrary to other cemented femoral components that have also provided excellent survival in the long term but frequently associated with stem subsidence,

The CMK Stem, a highly polished double tapered femoral component with a quadrangular cross-section and a collar, filling the medullary canal, and cemented with a simple technique

does not subside up to 18-year follow-up.

What is Subsidence ?What is Subsidence ?

Subsidence below 2 mm may be probably absorbed by cement creeping and contributes to lock the stem but overloads the cement

Subsidence over 2 mm always induces a fracture of the cement mantle and is a loosening that may be tolerated

Because distal migration without varus tilt is often well clinically tolerated that might explain the good survival of taper-slip stem if only revision is considered as a failure.





through a rough surface : surface finishthrough a rough surface : surface finish


Why the polished stem became matt ?Why the polished stem became matt ?

•Initiation of stem loosening: Initiation of stem loosening:

debonding of the cement to prosthesis interfacedebonding of the cement to prosthesis interface

Improvement of the bond through a matt surfaceImprovement of the bond through a matt surface

Composite beam conceptComposite beam concept

11

Why the polished stem became matt ?Why the polished stem became matt ?

Manufacturer request to facilitate productionManufacturer request to facilitate production

22

Matt stem (CMK3)Vecteur Orthopédique

Polished stem (MKIII)Stryker Howmedica

Ra = 3m Ra = 0.4m

Ovalcross-section

Quadrangularcross-section

Stem Radiological loosening

Polished stems: 1 hip (revised)

related to PE socket wear

Matt stems:16 hips (9 revised)

3 related to PE socket

13 debonding at the bone cement interface

associated to femoral osteolysis

Matte stems loosening (CMK3)

1y 3y 5y

Matte stems loosening (CMK3)

0

20

40

60

80

100

0 2 4 6 8 10 12 14

Follow-up (Years)

% n

ot lo

osen

ed Polished stems

Matte stems

Femoral stems survival with radiologic loosening as the end-point

97.3%97.3%

78.9%78.9%

Log-rank test, p < 0.001

Significant lower survival for matt stems

Similar observations made with other stems designs:

- Exeter stem: Howie et al., JBJS Br, 1998

40 matt VS 40 polished stems, Minimum 9 year-FU

4 matt stems loosened, 0 polished stem

- Iowa Stem: Collis et al., JBJS Am, 2002

122 grit-blasted VS 122 polished stems, mean 5,8

year-FU

6 gritt-blasted stems loosened, 0 polished stem

DISCUSSION

Surface finish change Surface finish change

cross section change ?cross section change ?

What was our main mistakeWhat was our main mistake

VSVS

do not forget Micromotiondo not forget Micromotion

Fact:- Bone, cement and stem form a composite

- All mentioned materials have different E-ModuliCortex: 12 - 18 GpaPMMA: 1.8 GpaWHN Stainless Steel 250 Gpa

- As all material deform differently As all material deform differently under loadunder load

micromotion, settled by the stem, micromotion, settled by the stem, occursoccurs

SO ……… SO ………

With a Matt surface – No relative movement between stem and cement

possible

– Micromotions result in localy debonded areas at the bone cement interface which create an abrasive medium that induce osteolisys

Bon

e

PM

MA

Ste

m

While a polished surface (associated with a While a polished surface (associated with a good design)good design)

micro movements occurs at the stem-cement viscoelastic micro movements occurs at the stem-cement viscoelastic interface and the bone-cement interface is protectedinterface and the bone-cement interface is protected

Bon

e

PM

MA

Ste

m

- An increased cement-

prosthesis bond

- increases shear stresses at the

cement-bone interface

- and finally induces loosening

at the bone-cement interface

We conclude that

Round or Rectangular cross Round or Rectangular cross section ?section ?

Fact : Fact : Stems are prone to relative rotation Stems are prone to relative rotation when torque forces are appliedwhen torque forces are applied

Round vs Rectangular : peak stressesRound vs Rectangular : peak stresses

M2

M1

shear stressshear stress compressive stresscompressive stress

M1

F1a

F1b

a

b

Rounder cross section–Prevents peak stresses at the angle–But Increased shear stresses at the interface

Rectangular cross Rectangular cross sectionsection

–Might induce peak Might induce peak stressesstresses–Applies compressive Applies compressive stresses on the stresses on the cementcement

Too round results in problemsToo round results in problems

Too edgy might result in problemsToo edgy might result in problems

(increased hoop stresses)(increased hoop stresses)

Look for a Look for a compromisecompromiseAlmost rectangular with smooth anglesAlmost rectangular with smooth angles

cross section design : delicate choicecross section design : delicate choice

Results of the first generation of CMKResults of the first generation of CMK

Charnley: Radiological aseptic femoral looseningCharnley: Radiological aseptic femoral loosening220 hips220 hips

Charnley: Radiological aseptic femoral looseningCharnley: Radiological aseptic femoral loosening220 hips220 hips

50%50%

60%60%

70%70%

80%80%

90%90%

100%100%

00 55 1010 1515 2020

74%74%

Long term results : elderly patientsLong term results : elderly patients

Charnley Kerboull stem aseptic femoral loosening200hips mean age 65 years old

Charnley Kerboull Charnley Kerboull stemstem aseptic femoral looseningaseptic femoral loosening200200hips mean hips mean age 65 age 65 years oldyears old

70%70%

80%80%

90%90%

100%100%

00 55 1010 1515 2020

98%98%

CharnleyCharnley rate : 74%rate : 74%

polishpolish

RCO, 1995RCO, 1995

Long term results : patients < 40 years oldLong term results : patients < 40 years old

European Journal of Orthopaedic Surgery and TraumatologyEuropean Journal of Orthopaedic Surgery and Traumatology1996, 6, 241-2461996, 6, 241-246

Long term results : Long term results : CDHCDH

Journal of ArthroplastyJournal of Arthroplasty2001, 16, N°82001, 16, N°8

Charnley vs CMKCharnley vs CMK

30 Y14 Y

Longterm featuresLongterm features

No cement under the tip

Dysplastic stems and acetabular Dysplastic stems and acetabular reconstructionreconstruction

20 years

Results of the next generations of CMKResults of the next generations of CMK

Long term results in patients under 50Long term results in patients under 50CORR, 418, Jan 2004CORR, 418, Jan 2004riesries

• 287 THR performed from 1975 to 1990287 THR performed from 1975 to 1990• Randomly sorted from a cohort of 2804 patientsRandomly sorted from a cohort of 2804 patients• Senior and junior surgeonsSenior and junior surgeons• 222 patients, 144 females and 78 males222 patients, 144 females and 78 males• MeanMean age : 40,1 y ( ± 8 y ; 15,5 - 50 y). age : 40,1 y ( ± 8 y ; 15,5 - 50 y).• Mean weight : 63 kg (Mean weight : 63 kg (± 18,2 kg ; 37 – 116 kg) ± 18,2 kg ; 37 – 116 kg)

0

20

40

60

80

100

120

StatusStatus Mean follow-up Mean follow-up (years)(years)

Number of hipsNumber of hips

ReviewedReviewed 16,1 16,1 ± 4,6± 4,6 210 ( 73,2%)210 ( 73,2%)

Died of Died of unrelated causesunrelated causes

5,4 5,4 ± 3,1± 3,1 10 (3,5%)10 (3,5%)

Lost to follow-Lost to follow-upup

10,8 ± 5,110,8 ± 5,1 42 (14,6%)42 (14,6%)

RevisedRevised 12,6 ± 6,112,6 ± 6,1 25 (8,7%)25 (8,7%)

Mean follow-up : 14,5 years Mean follow-up : 14,5 years ( (±± 5.1, 6m to 25 y) 5.1, 6m to 25 y)

52 hips had a follow-up greater than 20 years52 hips had a follow-up greater than 20 years

Radiological results : Stem looseningRadiological results : Stem loosening

No No looseningloosening

Definite or Definite or probable probable looseningloosening

Potential Potential looseningloosening

Number Number

of hipsof hips

271271

95,1%95,1%12124,2%4,2%

44

0,7%0,7%

10 aseptic, 1 septic, 1 after a periprosthetic fracture

Radiological loosening : stemRadiological loosening : stem

Implants Implants designdesign

SurfaceSurface SectionSection AsepticAseptic

looseninglooseningHipsHips

MK IMK I PolishedPolished QuadrangulQuadrangularar

1 0,7%1 0,7% 139139

CMK 2CMK 2 MatteMatte OvalOval 2 4%2 4% 5151

MK IIIMK III PolishedPolished QuadrangulQuadrangularar

00 2727

CMK 3CMK 3 MatteMatte OvalOval 8 8 11,5%11,5%

7070

Matt vs Polished : p = 0,0001

Survival rate : revision for any reasonSurvival rate : revision for any reason

0

,2

,4

,6

,8

1

0 5 10 15 20 25 30

20 years85,4%

95% sup : 92,4 %95% inf : 78,4 %S

uv

iva

l rat

e %

Su

viv

al r

ate

%

Follow-up yearsFollow-up years

P= 0,0001P= 0,0001

Survival rate : stem loosening, surface Survival rate : stem loosening, surface finishfinish

Su

viv

al r

ate

%S

uv

iva

l rat

e %


0

,2

,4

,6

,8

1

0 5 10 15 20 25 30

polishedpolishedmattmatt

88,5%

96,4%

Survival rate : PE wear dependantSurvival rate : PE wear dependant

0

,2

,4

,6

,8

1

0 5 10 15 20 25 30

Wear <= 0,1 94,8 %

Wear > 0,1 70,6 %P = 0,002

Su

viv

al r

ate

%S

uv

iva

l rat

e %


What we learnt at the end of this studyWhat we learnt at the end of this study

• The Kerboull cemented prosthesis The Kerboull cemented prosthesis

could provide satisfactory and could provide satisfactory and

durable results for 20 years in 85 durable results for 20 years in 85

% of patients younger than 50 % of patients younger than 50

years.years.

• The stem has a reliable fixation The stem has a reliable fixation

without subsidence and without subsidence and with a with a

simple surgical techniquesimple surgical technique

• So in our mind it remains a good So in our mind it remains a good

solution and reliable solution even solution and reliable solution even

for young patientfor young patient

What we learnt at the end of this studyWhat we learnt at the end of this study

• Stem design and surface finish are the most important Stem design and surface finish are the most important

factors. factors.

• Surface must be definitely polished to protect bone-Surface must be definitely polished to protect bone-

cement interface from overloading.cement interface from overloading.

• Cement is weak, and must be protected by the stem of Cement is weak, and must be protected by the stem of

excessive tensile and shear stresses, and just used to excessive tensile and shear stresses, and just used to

fill the gap between the bone and a canal-filling stem. fill the gap between the bone and a canal-filling stem.

• Following these mechanical principles cement quality, Following these mechanical principles cement quality,

cement thickness and cementing technique become cement thickness and cementing technique become

minor concernsminor concerns

• Be careful, the classifications and terminology used in Be careful, the classifications and terminology used in

the literature are confusing because they mainly refer the literature are confusing because they mainly refer

to the cementing technique and not to the design and to the cementing technique and not to the design and

the surfacethe surface

• The CMK is a loaded taper but initially stable due to its The CMK is a loaded taper but initially stable due to its

fitting to the medullary canalfitting to the medullary canal

Thank you for Thank you for your attentionyour attention

• Trust the stem design more than

the cement mantle ．

the charnley kerboull hip system results of a 30 years experience in cemented fixation l kerboull, m...

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