Cementless TKA

Cementless TKA

Anthony S Unger MDCharles Milchteim, MD

Why not cement?

• Cement fixation will eventually fail

• In patients younger than 50 years, implant survivorship in cemented arthroplasty has been reported as low as 85% at a 15-year – Duffy et al J Arthroplasty

2007)

The argument for cementless TKAs

• Osseointegration is more physiologic

• Bone stock preservation

• Durability (key in younger pts)

• New implant designs and materials addressed earlier deficiencies

• There is long term data to support it

Evolution of cementless TKA

• Earlier designs were fraught with complications and high failure rates:

• Berger et al CORR 2001– 131 TKAs @ 11 yr f/u

– 8% failure of ingrowth

– 53% partial radiolucency (especially around screws)

– Authors abandoned cementless fixation

Smooth tibial components•Nafei et al JBJS 1992

– Kinemax (FB, CR)– Smooth central peg– 79 cementless TKAs @ 14 month

f/u– 20% loosening rate– 24% residual pain

•Results confirmed by Cloke et al Acta Orthopedica 2008

– 76% survival rate @ 11yr f/u



Metal-Backed patella

•Stulberg et al CORR 1988–Polyethylene dissociation followed by wearing of the metal backing against the femoral component.

•Rosenberg et al CORR 1988– n=122 porous Ti fiber mesh patella– Pegs had bony ingrowth but baseplate did not–Failure of osseointegration leads to eccentric loading and shear of the peg-plate junction failure

Evolution of cementless fixation

Highly porous materials•Trabecular Metal

– Elemental tantalum deposited onto a highly porous vitreous carbon strut

– Added porosity may afford better initial mechanical fixation and ultimate osseointegration (Bobyn et al JBJS 2004)

– Biomechanically similar to cancellous bone

– Less bone resorption when compared with older, stiffer implants

• HA coating

• Functional results and survivorship of comparable to cemented implants.

• Beaupre et al JBJS 2007– 81 pts randomized to HA-coated or

cemented (Scorpio Co-Cr)

– No differences in function, radiographic findings, or complications @ 5 yrs

• Cosseto et al J Arhtroplasty 2001– Survivorship of 98.85% and bony ingrowth

in all but one pt Beaupre LA, J Bone Joint Surg Am. 2007;89-A:2204–2211.Cross MJ J Bone Joint Surg Br. 2005;87-B:1073–1076.Oliver MCJ Bone Joint Surg Br. 2005;87-B:478–482.Onsten I J Bone Joint Surg Br. 1998;80-B:417–425.

Insall-Burstein II


Biomet Regenerex

• Porous Titanium base, smooth pegs

• “Better fixation, roughness and compressive strength than TM” (Biomet data)

• Compressive modulus comparable to cancellous bone

• Three peg monoblock patella

*No long term data


Bone Stock Preservation

• Minoda et JBJS 2010– Prospective 56 knees (TM vs

cemented) using DEXA– Significantly smaller decrease in

BMD of lateral tibial plateau @ 2-yr f/u

• Seki et al J Ortho Sci 1999– 2-fold decrease in BMD loss in

cementless distal femora @ 2-yr f/u

• Revision is easier

Ease of Insertion• No cement!• Implants can be placed using

MIS technique• Compared with standard

parapatellar approaches, “mini mid-vastus” MAY lead to improved ROM, faster recovery, decrease in narcotic reqs– Haas et al COOR 2004

• N= 335 retrospective, compared to historical controls

– Laskin et al COOR 2004

(Theoretical) Advantages

(Theoretical) Advantages

• MIS technique: no increase in component malalignment in a randomized study– Chin et al J Arthroplasty 2007

• Implantation is less demanding, leads to shorter OR times and may subsequently decrease the incidence of perioperative infection.– Scuderi et al JBJS 2009

Cementless Data

• Gandhi et al JBJS 2009

Khaw et al JBJS 2002McCaskie et al JBJS1998

– Both level I studies– DePuy FB, CR press-fit Condylar Knee

(PFC); same implant available for implantation with or without cement

– N=277 cemented; n=224 cementless– No difference in pain, mobility or ROM,

radiological alignment– 95% survivorship @ 10 yrs regardless of

fixation method – Cemented: significantly greater # of

radiolucent lines on AP of the tibia and lateral of the femur.

– However, cementless more $$$...

Is there enough data to support cementless TKA?

Ritter et al J Arthroplasty 2010•Biomet AGC (cruciate retaining)•Plasma sprayed porous Ti coating on undersurface; smooth stem; metal-backed patella•N=73 TKAs @ 20 yr f/u

•Age=59; BMI=26

•NWB x8 wks postop

Study funded by Biomet

More data…

Ritter et al J Arthroplasty 2010

•Results:– 12 failed patellae,– Excluding patella failures,

survivorship of tibial component= 96.8% @ 20yrs

– No femoral component failures

More data…

• Whiteside L CORR 2001– Ortholoc (Wright medical)– CR, FB, porous-coated

undersurface but smooth pegs/stem

– N=265

– 98.6% survival @ 18yrs

– 80% pain-free

– Those undergoing revision= good bone stock

Our Experience• Unger et al J Arthroplasty

2011– N=177– CR, FB, Zimmer TM

monoblock tibia, uncemented TM monoblock patella (n=90), cemented all poly-patella (n=87), uncemented high-flex femur (n=108), cemented high-flex femur (n=69)

– Mean age: 66 yrs; f/u 5.1yrs

Results• 7/177 revisions

– 4 patella– 1 patella fx after fall– 1 femoral loosening– 1 infection

• 11 knees that had a femoral radiolucency under anterior flange

• KSS: 46 88• One tibial component settled 8mm

over first 2 yrs but stabilized; other 176 showed excellent bony apposition at final f/u

CEMENTLESS TKA –RECENT STUDIES

• SIGNORELLI, J.J., J OF ARTHROPLASTY 26:3, 2011– 100 SIGMA PFC UC ROTATING PLATFORM– 2 YR MIN FU– 1 REVISION– 99% SURVIVAL

CEMENTLESS TKA-RECENT STUDIES

• KAMATH, A.F. J OF ARTHROPLASTY, 26:8, 2011– 100 TM MONOBLOCK– AGE <55 YRS– NO FAILURES– COMPARED TO CEMENTED PS TKA—NO

DIFFERENCE

Unanswered questions

Component migration•TM subsidence and posterior tilt•effect on long-term survivorship= ????•Occurs primarily during initial 3 mos. and then stabilizes•Dunbar et al JBJS 2009

– Level I study sponsored by Zimmer– C:33 N:37(TM) (Both Zimmer NexGen)– RSA @ 2 yrs: initial migration >1mm in 9

cementless but @ final f/u none at risk of loosening; 4/28 cemented at risk for loosening; 5/28 cemented = +lift-off (superior migration >0.1mm)

COST ANALYSIS

• AVERAGE COST $500-750 MORE FOR UNCEMENTED IMPLANT

• SAVE $750 FOR CEMENT AND MIXING BOWL

• COST SAVINGS IN OR TIME

• INCREASED EFFICIENCY

CONCLUSIONS

• CEMENTLESS TKA HAVE SAME RELIABILITY AS CEMENTED

• CEMENTLESS TKA ARE PROBABLY MORE DURABLE

• COSTS ARE ACCEPTABLE

• WE WILL SEE INCREASED DEMAND FOR THIS TECHNOLOGY

THANK YOU

Cementless TKA

Health & Medicine

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