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Torsional F

NTRODUCTIONFrictional torqu

oading and motiacetabular bone - iThe purpose of thpress-fit acetabulaconventional pressdesign. The dual marticulation (Figurpolyethylene inserpolyethylene insert

MATERIALS ANTest Specimen

PSL and AnatomicNJ) were tested inhell groups were

polyethylene inserfemoral heads. Gpolyethylene inserwere tested with a OD LFIT CoCr femof the LFIT (lowmplantation proce

been reported to articulating with cassembled with commercially avaMahwah, NJ).

Deformed Shelwas created in a pdensity of 30lb/mplantation [3]. echniques, the blo

and this provided aand Trident shelechniques). The single axis MTS T

force at a rate of 5block was then claimulate in vivo enHyclone, Logan,

constant axial loaunderwent angularhell for 100 cycles

A torque cell at theHz. Maximum absohe data acquired.

Figure 2. Two-PoConfiguration

Forces Genera

+1 Ra

N ue is generated aton. These torsioimplant interface, his study was to ar shells generates-fit acetabular shemobility shells arre 1), one betwrt (external beart and a femoral hea

ND METHODS ns: 54mm outer dc Dual Mobility (An both undeformedtested: Group onerts and Low FricGroup two was rts and LFIT CoC48mm OD ADM moral head. The

w friction ion tress has been in clireduce the linearconventional poly

Ti6Al4V trunnailable taper des

l Testing: A two-polyurethane foamft3, to replicate Consistent with cks were machinea diametrical pressls, respectively

shells were assemTest System (MT5mm/min until theamped onto a 3-axnvironment, 50% UT) was applied

ad of 2450N wasr displacement of s at a rate of 0.75He base of the test frolute torque was r

int Relief

Figu

ated in Press-F

aja, L K; 1Scholl, L+1 Stryker Orthop

t the hip joint dunal forces are trwhich may influeinvestigate whet

e less torque whells that have a fire designed to ha

ween the acetaburing) and the otad (internal bearin

diameter (OD), SADM) shells (Stryd and deformed ste was tested with ction Ion Treatme

tested with 44Cr femoral heads.

X3 polyethylene iCoCr heads used

reatment) type. Tnical use for over

r wear rate by 28yethylene [2]. Allnions machined sign, V40 (Stryk

-point relief configm block (Pacific L

shell deformatADM and Tride

ed to simulate “lines-fit of 1.5mm and(as prescribed b

mbled into the foaS Corp, MN) by shells were comp

xis MTS Test Systdiluted Alpha Cad to the articulats applied while ±20º about the c

Hz. [4, 5]. rame measured torecorded for each t

Figure 3. T

ure 1. Dual Points

Fit Acetabular

L; 1Schmidig, G; 1Hpaedics, Mahwah,

lokeshkum

uring normal gaitransmitted to the

ence loosening [1]ther dual mobilityhen compared toxed bearing insert

ave dual points ofular shell and ather between the

ng).

Solid-back Tridentyker Orthopaedicstates. Two Trident28mm Trident X3ent (LFIT), CoCr

4mm Trident X3The ADM shells

insert and a 28mmin this study were

This nitrogen ionr a decade and has8% in vivo whenl specimens were

to replicate aker Orthopaedics

guration (Figure 2)Labs, WA) with ation upon initiaent shell surgicae to line” reamingd 1.8mm for ADMby their surgicaam blocks using a

applying an axiapletely seated. Thetem (Figure 3). Toalf Fraction Serumting interfaces. Athe femoral head

central axis of the

rque at a rate of 25test specimen from

Test Setup

s of Articulation

r Shells with F

Heffernan, C; 1ThaNJ, 2 St. Margaretmar.raja@stryker.c

t e .

y o t f a e

t , t 3 r 3 s

m e n s n e a ,

) a l l g

M l a l e o

m A d e

5 m

Una stainto-linesame p SpeANOVundefocompa RESU Tabmobiliaveragfor eac

SheDe

Und In btorque44mmtwo gcompaundefothe du(p<.05It wasin aveboth hdeform DISC Shediameutilizethis stlowerbearinbenefihead/tNm into dispolyur Thean effthis stwhen perpennecesscompa SIGN

Fricfailurestudy design REFE[1] MMaruy[3] JinSchmiN.E. eal. Trmeetin

Fixed and Dua

akore, M; 1Nevelot’s Hospital, Springcom

deformed Shell Tnless steel block we fit with the shelprocedure as the decimen groups wVA test and a Tukormed and deforare individual prod

ULTS ble 1 contains theity and fixed bearge and standard dch individual test s

Table 1. Resu

ell State

FBear28m

eformed 3.5deformed 1.77both undeformed

e generated betweem heads was not stgroups were comarison with the dormed states, the ual mobility and f5). s observed that theerage torque generhead sizes tested; med and undeform

USSION ell deformation heter metal on mete a similar monobltudy suggest that s

torsional forcesng acetabular shelit both in terms of trunnion interfacen this study was sigslodge a Trident rethane block mode results of this stufect on torsional fotudy, we looked at

the head is rondicular load is asarily replicate pharing torsional valu

NIFICANCE ctional torque hae in some monobldemonstrated the

n do not generate e

ERENCES Ma, SM., et. al., J

yama, M., et. al., Cn, ZM., et. al., Pidig, G. et. al. J Aet. al., Medical Engrans ORS 2011, Png of the Orthopae

al Mobility Be

s, J; 2Perona, P G g Valley, IL

Testing: Each acewith a hemisphericll OD. The insertedeformed specimenwere statistically ckey post-hoc test atrmed states. Paireduct families in de

e results of the tring shells (n=5). deviation of maximspecimen is provid

ults - Maximum AFixed ring with

mm head

FBea44m

8 ± 0.87 3.87 ± 0.28 2.0and deformed sta

en the fixed bearintatistically signific

mbined into a sindual mobility shel

difference in averfixed bearing she

ere was statisticallrated for fixed beaNo significant dif

med dual mobility s

as been implicatetal bearings [6]. lock metal acetabushells with dual mo

as compared to lls in the deformef forces at the impl. The largest avegnificantly less thashell similar to

del [7]. udy suggest that sorces generated in t torsional forces g

otated about its applied to the shehysiological condiues between impla

s been raised as ock shell implant dual mobility she

elevated torsional f

Bone Joint Surg Clin Orthop RelatProc. Inst Mech rthroplasty, 2010 g. and Physics, 20

Poster 1210. [7] Tedic Research Soci

earing Insert D

etabular shell was al cavity that resued shells were tesns. compared with at 95% confidence ed t-tests were p

eformed and undef

testing performedFor each specime

mum absolute torded.

Absolute Torque (Fixed ring with

mm head

Duawith

in86 ± 0.26 1.00 ± 0.36 1.ates, the differencng shells with 28mcant. (p<0.05). Thengle fixed bearinlls. In both the drage torque generlls was statistical

ly significant (p<0aring shells whenfference was obsershells (p>0.05).

ed in shell failure Many dual mob

ular component. Tobility bearing des

conventional preed condition. Thilant/bone interface

erage measured toan the 68.4 Nm tothat used in thi

hell deformation ddual mobility AD

generated in a bencentral axis and

ell. While this moitions, it provides ant designs.

an issue, which designs when def

ells that also use forces when defor

Am, 1983, 65(3)t Res, 2000 Jan, (3Eng [H], 2006, Jun, 25(4), 644-53

008, 30, 1057-64.; Thakore, M et. al.iety, 2009, Poster

Designs

assembled in ulted in a line-sted using the

single-factor level for both performed to formed states.

d on the dual en group, the rque recorded

(Nm) al Mobility h 48/28mm

nsert/head .48 ± 0.28 .46 ± 0.24 ce in average mm heads and erefore, these

ng group for deformed and rated between ly significant

0.05) increase deformed for rved between

es with large bility designs The results of signs transmit ess fit, fixed is may be of e and also the orque of 3.86 orque required s study in a

does not have DM shells. In nch-top model d a constant odel does not

a means for

may lead to formed. This a monoblock

rmed.

), 366-70; [2] 370), 183-91; 220-299; [4]

3; [5] Bishop, [6] Grimes et , 55th Annual # 2024.

Poster No. 1057 • ORS 2012 Annual Meeting