Conservative Hip Conservative Hip

Replacement for Replacement for

avascular necrosisavascular necrosisE. Munting, P. PoilvacheE. Munting, P. PoilvacheCliniques Universitaires Saint-Luc, Cliniques Universitaires Saint-Luc,

BruxellesBruxellesClinique Saint-Pierre, OttigniesClinique Saint-Pierre, Ottignies

Hôpital de Waterloo-BraineHôpital de Waterloo-Braine

THR in patients < THR in patients < 55 y.55 y.Revision rate :Revision rate : from 20 % at 5 yearsfrom 20 % at 5 years

to 12 % after 20 years follow-up to 12 % after 20 years follow-up

- - Conflicting reportsConflicting reports

- Implant dependent- Implant dependent

- Patient dependent (activity…)- Patient dependent (activity…)

Femoral component : Femoral component : optionsoptions

Preservation of the femoral head Preservation of the femoral head

and resurfacingand resurfacing

Replacement of the femoral head Replacement of the femoral head

and :and :

fixation in the diaphysis (stem)fixation in the diaphysis (stem)

fixation in the metaphysisfixation in the metaphysis

Femoral head replacement Femoral head replacement with metaphyseal fixation with metaphyseal fixation

… an old idea !… an old idea !

19381938 WilesWiles 19541954 Postel and Merle d'AubignéPostel and Merle d'Aubigné

19411941 McKeeMcKee

19491949 Judet and JudetJudet and Judet

19521952 ThomsonThomson

19531953 HaboushHaboush

1957 1957 PicchioPicchio

1980 1980 Huggler and JacobsHuggler and Jacobs

19821982 Munting and VincentMunting and Vincent

Specification chart Specification chart

Preserve bone stockPreserve bone stock

Normal stress pattern in the boneNormal stress pattern in the bone

Femoral head replacementFemoral head replacement

Easy revisionEasy revision

Conception and Conception and Experimental Experimental workwork Design and biomechanical assessment Design and biomechanical assessment

of prototypes on a hip simulator of prototypes on a hip simulator

Finite Element analysis of Finite Element analysis of

experimental and clinical casesexperimental and clinical cases

Hydroxyapatite coating development Hydroxyapatite coating development

and animal experimentsand animal experiments

Implant design Implant design studystudy

Femoral Femoral componentcomponent

No medullary stemNo medullary stem

Screws for initial Screws for initial

fixationfixation

Hydroxyapatite coatingHydroxyapatite coating

Modular headModular head

Angular resection of Angular resection of

the femoral neckthe femoral neck

Lamellae in the Lamellae in the

proximal metaphysisproximal metaphysis

Cortical and Cortical and

cancellous supportcancellous support

Fixation :Fixation :Geometrical Geometrical interferenceinterference

DXA StudyDXA Study(prospective, 21 hips, 6-9 (prospective, 21 hips, 6-9 y. F-up)y. F-up) BMD is maintained in the BMD is maintained in the

proximal femurproximal femur In patients with low initial values In patients with low initial values

asas

compared to the controlateral compared to the controlateral side, side, BMD increases after surgeryBMD increases after surgery J. Arthroplasty 12, 373-9, 1997

Pilot studyPilot study

04/1989 – 01/199204/1989 – 01/1992

43 patients, 48 hips43 patients, 48 hips

33 males, 15 females33 males, 15 females

Mean age: 36.4 years (19 – 49)Mean age: 36.4 years (19 – 49)

Etiology Etiology (pilot study n (pilot study n = 48)= 48)

Primary arthritisPrimary arthritis 6 6 rheumatoïd arthritisrheumatoïd arthritis 4 4 Ankylosing spondylitisAnkylosing spondylitis 5 5 Septic arthritisSeptic arthritis 2 2 Post-traumatic arthritisPost-traumatic arthritis 7 7 Congenital dysplasia / dislocationCongenital dysplasia / dislocation 6 6 Aseptic necrosisAseptic necrosis

1212 Miscellaneous Miscellaneous 6 6

ResultsResults (pilot study (pilot study n: n: 4848))

Follow-up : 14 to 16 yearsFollow-up : 14 to 16 years 1 patient (2 hips) deceased1 patient (2 hips) deceased 3 lost to follow-up (living abroad)3 lost to follow-up (living abroad) 18 revised18 revised : : 8 early revisions 8 early revisions

(malposition)(malposition) 10 late revisions 10 late revisions (polyethylene wear)(polyethylene wear)

26 hips known to be functional.26 hips known to be functional.

Revisions secondary to Revisions secondary to implant malposition implant malposition (n=8)(n=8)

Varus positionVarus position : :

CDA CDA << 120° (n=6) 120° (n=6)

lack of contactlack of contact with with

the bone resection the bone resection

(n=2) (n=2)

Second seriesSecond series

01/1995 – 05/200001/1995 – 05/2000

154 hips154 hips

Mean age: 40.8 years (17 – 56 years)Mean age: 40.8 years (17 – 56 years)

Second series Second series (01/1995 – (01/1995 – 05/2000)05/2000)

154 hips154 hips

14 early revisions14 early revisions

4 late revisions for poly. 4 late revisions for poly.

wear (alumina/poly.)wear (alumina/poly.)

Survival probability: Survival probability:

femoral componentfemoral component

0,70

0,75

0,80

0,85

0,90

0,95

1,00

0 2 4 6 8 10 12

( Kaplan - Meier )

n = 48 pilot studyn = 48 pilot study

y

n = 154 second seriesn = 154 second series

Third series Third series (06/2000 – (06/2000 – 11/2005)11/2005)

130 hips130 hips

Mean age: 42 y. (14-56)Mean age: 42 y. (14-56)

9 early revisions:9 early revisions:

2 broken ceramic heads 2 broken ceramic heads

(alumina/alumina)(alumina/alumina)

Aseptic necrosis Aseptic necrosis (69 hips)(69 hips)

Aseptic necrosisAseptic necrosis

From 04/1989 to 02/2003From 04/1989 to 02/2003 56 patients (50 males/6 females)56 patients (50 males/6 females) 64 hips64 hips Mean age: 49 years (22 – 64)Mean age: 49 years (22 – 64) Mean follow-up: 7 yearsMean follow-up: 7 years 5 revisions5 revisions 59 implants still in place59 implants still in place

Aseptic necrosis (n: Aseptic necrosis (n: 64)64)

5 revisions (7.8%)5 revisions (7.8%)

Mean age at reoperation: 52 yearsMean age at reoperation: 52 years

Mean time in situ: 3 yearsMean time in situ: 3 years

Reasons for revision:Reasons for revision:

Varus positioning causing pain or Varus positioning causing pain or

loosening (4)loosening (4)

Recurrent dislocation (1)Recurrent dislocation (1)

Aseptic necrosis (n: Aseptic necrosis (n: 64)64)

59 implants in place:59 implants in place:

1 patient complaining of groin pain (psoas 1 patient complaining of groin pain (psoas

tendinitis?)tendinitis?)

1 late instability (poly. wear)1 late instability (poly. wear)

2 patients with mild trochanteric pain (screw?)2 patients with mild trochanteric pain (screw?)

7 years7 years 14 years14 years

Need for improved Need for improved instrumentsinstruments

The cutting and drilling guides should be monoblock, in order to avoid rotational mismatch

ConclusionsConclusions This experience supports that This experience supports that a purely a purely

metaphyseal anchorage of a stemless implant metaphyseal anchorage of a stemless implant

can provide a long lasting fixationcan provide a long lasting fixation This type of implant is This type of implant is suitable even when the suitable even when the

femoral head is destructedfemoral head is destructed It permits the use of a It permits the use of a ceramic on ceramic ceramic on ceramic

bearingbearing It is conservative, as It is conservative, as a primary implant can a primary implant can

easily be used if revision is neededeasily be used if revision is needed