Ceramic on Poly THA Darwin Chen, MD Assistant Professor Mount - - PowerPoint PPT Presentation

Darwin Chen, MD Assistant Professor Mount Sinai Medical Center Department of Orthopaedic Surgery

Ceramic on Poly THA

▶ Monogram Orthopedics

– Consultant

Disclosures

Darwin Chen, MD Assistant Professor Mount Sinai Medical Center Department of Orthopaedic Surgery

Why Bother With Anything But Ceramic on Poly THA?

Ceramic liner fx Metal-metal failure Dual mobility disassociation Taper corrosion – M on P

Trends in Total Hip Arthroplasty

▶ The fundamentals have not changed! ▶ Major challenge – implant longevity

– Patients living longer

• 1/3 of ♀ age 50 will live to be 100

– Expanding THA indications

• Younger, more active
• Higher functional demands/expectations

Sir John Charnley at his lathe, creating the first THA implants

Goals of the Bearing Articulation

▶ Minimize wear/biologically active debris ▶ Maximize hip stability ▶ Avoid bearing related complications ฀Pre

• p

฀Santoro, J

Which Bearing Should I Use for My Patient?

▶ Age? ▶ Activity level?

– Metal on poly – Ceramic on poly – Ceramic on ceramic – Metal on metal – Ceramic on metal

Bedard, Callaghan, JoA 2017

Osteolysis Directly Correlates With Wear

▶ “Threshold” for osteolysis is <0.1mm/yr (~650mm3)

Looney RJ 2002 Dumbelton JH, JoA 2002 Wilkinson JR, JOR 2005 Dowd, JBJS 2000

Larger Heads = Better Stability

Berry, 2005

Larger Heads = Better Stability

Howie, 2012

At one year following surgery:

28mm 36mm Primary 4.4% 0.8% Revision 12.2% 4.9% Overall 5.4% 1.3%

Larger Heads = Better Stability

Garbuz, 2012

How is Metal on XLPE Doing?

▶ Pretty well!

Feb 2013

– CoCr on XLPE, 7-10yr f/u – 28mm wear rate 0.012mm/yr – 32mm wear rate 0.01mm/yr – No osteolysis

How is Metal on XLPE Doing?

▶ Pretty well!

Sept 2016

– CoCr on Longevity XLPE, 28mm and 36mm – Mean wear @ 13 yrs = 0.05mm/yr – No difference between sizes – No osteolysis

Taper Corrosion

▶ Corrosion of CoCr head on Ti stem, ↑ Co/Cr ions ▶ An “emerging” problem with M on P ▶ Multifactorial

– Taper geometry, metallurgy, head size, assembly technique

▶ Can cause mild to severe ALTR

– Late instability, abductor damage, osteolysis

Cooper, 2012

Taper Corrosion

▶ Ceramic head significantly reduces potential for taper corrosion

– Significantly greater metal release (11x increase in Co and 3x increase in Cr) from a CoCr / CoCr interface when compared to a Co-Cr / ceramic interface – Corrosion can still occur

▶ When used with a titanium stem, no source of Co and Cr debris that can

lead to ALTR

Cooper, JBJS(Am) 2013)

Delta Ceramic

▶ Matrix composite ceramic ▶ Zirconia toughened, platelet reinforced,

alumnia ceramic

▶ 82% alumina, 17% zirconia, 0.5%

strontium aluminate, 0.5% chromium oxide

Ceramic on Poly

▶ Avoid issues with hard-hard bearings ▶ Properties of ceramics further reduce wear characteristics of

XLPE

▶ Delta ceramics

– 50% stronger than alumina – More abrasion resistant than CoCr – 3x hardness of CoCr – Wettable – Biocompatible

Wear Rate - Ceramic on Poly

▶ Simulator data shows clear advantage of C-on-P over M-on-P

, 40-50% reduction

Fisher, 2006 Galvin, Proc Inst Mech Eng 2010 Kim, 2005

CoCr Ceramic Total Linear Wear 1.21 mm 0.57mm p = 0.004 Linear Wear Rate 0.17 mm/yr 0.08 mm/yr p = 0.004 Volumetric Wear 744.7 mm3 350.8 mm3 p = 0.004

Comparison Testing

Bradgon 2006, Greenwald 2006, Manning 2005, Martell 2003, Zichner 1992,1997

Ceramic Head Fracture

▶ Historically, ceramic head fracture was a

significant clinical concern

– Old aluminas were low density, coarse microstructure, not in compliance with today’s specifications

▶ Current alumnia and Delta ceramic substantially

improved mechanical strength

▶ Biolox ceramic head fx rate

– 0.026% 1st gen Alumina – 0.014% 2nd gen Alumina – 0.004% Delta

Willmann, Clin Orthop 2000

Ceramic Head Fracture

▶ Delta head

fractures are negligible with 32/36 heads

Ceramics – Less Risk of PJI?

Ceramtec, Inc.

▶ In theory, ceramics have less bacterial biofilm formation due to decreased

surface roughness and molecular composition

▶ Reduced wear = reduced bio-burden of PE particles, less inflammation ▶ No Co, Cr ion release – no immune suppression?

Ceramics – Less Risk of PJI?

March 2017

▶ Medicare database (315,784 patients) ▶ C-P and C-C exhibit lower risk of infection comparted to M-P

(C-P hazard ratio 0.86, p=0.001. C-C hazard ratio 0.74, p=0.01)

▶ C-P reduced risk of dislocation and mortality

(HR 0.81, p<0.001, HR 0.92. p<0.001)

Conclusions

▶ In 2018, ceramic on poly is the best choice for most THAs ▶ Excellent wear properties ▶ Eliminates the metal ion problem ▶ No squeaks, negligible fracture risk ▶ Reduced PJI? ▶ Forgiving, no change in technique

Thank You

Darwin Chen, MD Assistant Professor Mount Sinai Medical Center Department of Orthopaedic Surgery