Pseudo tumor a cystic or solid mass (MRI or ultrasound) 1% of MOM pts develop pseudo tumors by 5 years 17 pts, all female, Pandit et al (JBJS, 2008)

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1 Pseudo tumor a cystic or solid mass (MRI or ultrasound) 1% of MOM pts develop pseudo tumors by 5 years 17 pts, all female, Pandit et al (JBJS, 2008) 8% at 5yrs FU indicated by preliminary study from same group (AAOS 2009) Large posterolateral cyst arising from the posterior joint space (arrow) in a T2-weighted MR scan Tumors associated with: Histology indicating extensive necrosis diffuse lymphocyte infiltration Lower Oxford Hip Scores (20 vs 14, p=0.02) Higher serum cobalt levels (5.5 vs 1.7 µg/l, p=0.04) Pseudotumours associated with metal-on-metal hip resurfacings. Pandit H, Glyn-Jones S, McLardy-Smith P, Gundle R, Whitwell D, Gibbons CL, Ostlere S, Athanasou N, Gill HS, Murray DW. J Bone Joint Surg Br Jul;90(7): Prevalence of asymptomatic pseudo-tumours in patients with MOM hip resurfacing. Young-Min Kwon, Peter McLardy-Smith, Simon Ostlere, Hemant Pandit, Paul Monk, Adrian Taylor, David Beard, Hariderjit Gill, David Murray (AAOS 2009, Poster#40)

2 In use for over 20 years Plagued by: Sintering problems In vivo fracture and chipping Recent reports of squeaking hip

3 Ceramic on Ceramic Thanks to Dr. Ranawat, HSS

4 Most studies report: 20% noise, 10% squeaking 1% persistent/ symptomatic squeaking Varies from 0.7% to 40% 2 studies report greater incidence (8%-40%). Christian P Christensen, Cale Jacobs, Lexington, KY. Greater prevalence of early complications with ceramic-on-ceramic than with MOM THAs (Paper 197, AAOS 2009) Clifford Colwell, Kenny Mai, Christopher Verioti, Kace Ezzet, Steven Copp, Richard Walker. Incidence of Squeaking after COC THA:2-10 year follow-up (Paper 201, AAOS 2009) Todd Swanson, Ryan Bliss, Calvin Spellmon. Influence of prosthesis design on squeaking after ceramic-on-ceramic total hip arthroplasty. (Poster 97, AAOS 2009) Remi Nizard, Alexandre Cogan, Dider Hannouche, Laurent SiGismond Sedel. Noise occurrence after alumina-on-alumina hip arthroplasty. A survey on 284 consecutive hips

5 Metal/metal: Metallic debris and pseudo tumours Ceramic/ceramic: Squeaking Metal/highly x-linked poly: Potential fatigue failures

6 Considered a more forgiving bearing. Well documented performance over several decades Versatile (design, position and fixation) However, gamma or ETO sterilized (non cross linked) has been associated with a high frequency of mid-term radiographic osteolysis and subsequent clinical failure and revision.

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8 1st Generation Cross linked UHMWPEs

9 Muratoglu et al., JOA, 18(6), 2001; Muratoglu et al. JOA, 16:

10 Dome of the Articulating Surfaces Conventional WIAM Crosslinked at 5 million cycles at 5 million cycles at 25 million cycles at 25 million cycles

11 Wear Simulator Studies at MGH First clinical use of a new formulation of crosslinked polyethylene was in Cross-linked polyethylene is now widely used in total hip arthroplasty. Research continues into ways to optimize the use of this new technology. Pre-screening Pin-on-disk and Hip/knee Simulator studies were crucial part of pre-market development.

12 7-10 year follow-up study using 28 and 32 mm head diameter Large head and a RSA study (5 years FU)

13 286 THRs (263 patients) at a minimum of 6 years Having Longevity or Durasul Liners. 131 Women and 132 Men Average age at surgery of 61.6 years

14 Clinical Outcome Questionnaire Median Scores (range) Harris Hip Score 88.57±3.9 EQ-5D (general health) 0.84±0.2 SF-36 Physical Activity 47.47±10.7 SF-36 Mental Score 54.70±8.5 UCLA Activity Score 6.47±2.1

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16 Steady State Femoral Head Penetration: MGH 7-10 year F/U Series

17 Excellent clinical outcome (Harris Score etc). No revisions due to poly fracture or failure. No osteolysis when reviewing plain films. No detectable head penetration (evaluated by the Martell method) after the initial creep phase. Wear reduction thus close to 100%.

18 December 1998 control or study Cemented cup, unilateral operation October 2000 control study Uncemented cups, bilateral operation

19 Introduction Radiosteriometric analysis is a method for accurately measuring three dimensional relative displacements in vivo from sequential pairs of sterioradiographs. It requires the use of a calibration cage with fixed tantalum markers to reconstruct a 3-D co-ordinate system.

20 Introduction It also requires in vivo markers attached to the regions of interest so that they can be defined as rigid 3-D segments. RSA usually used on a relatively small group of patients.

21 Durasul study Kärrholm et al International Hip Society Hong Kong September 2008 Five to Seven Year Experience with Highly Cross-linked PE

22 Durasul study (7 yrs p<0.0001) Kärrholm et al International Hip Society Hong Kong September 2008 Five to Seven Year Experience with Highly Cross-linked PE

23 What is the clinical implication of this surprising finding for Durasul? Could highly x-linked poly suffer from accelerated wear past 5 years? Or does this represent a change in creep properties?

24 9 years in vivo service. Explanted due to recurrent dislocations CMM measurements didn t reveal any significant wear/deformation. The liner was mounted in the hip simulator with appropriate controls and for additional 5 millions cycles.

25 Total Weight Change for Each Sample (uncorrected)

26 Concerns over the Swedish RSA findings. Longer follow-up and more retrieved liners needed. Concerns about the mechanical properties of remelted highly cross linked poly although no liner fractures have been reported in the peer-reviewed literature. Can we improve polyethylene further?

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28 X3 (FDA cleared, Stryker) Sequentially irradiated and Annealed E-Poly ( FDA cleared, Biomet) Irradiated and doped with vitamin-e Free radicals stabilized by α-tocopherol (vitamin-e) Both X3 and E-Poly Higher crystallinity/higher strength High wear resistance High oxidation resistance

29 α-tocopherol (Vitamin E, α-t, T-OH) R + O 2 ROO ROO + T-OH ROOH + TO R + Vitamin-E

30 Machining of parts Radiation cross-linking (~100 kgy) in argon Immerse parts in vitamin E (D,L-α-tocopherol) Homogenize Gamma sterilization (25-40 kgy) in inert

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32 Antioxidant infused technology e-poly. Oral et al. J Arthroplasty 21: (2006)

33 Study managed by the Harris Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital Henrik Malchau, MD, Charles Bragdon, PhD, Meridith Greene, BA

34 Study managed by the Harris Orthopaedic Biomechanics and Biomaterials Laboratory at Massachusetts General Hospital Henrik Malchau, MD, Charles Bragdon, PhD, Meridith Greene, BA

35 The study is designed to document the long-term (10- years) radiographic and clinical outcomes of the Antioxidant infused technology (E-Poly), in a group of primary total hip arthroplasty patients. The clinical outcome of E-Poly will be compared to existing long-term clinical data and ArCom.

36 Prospective, multi-centric observational study. Randomization optional at the individual centers. Four arms: Ring-Loc with ArCom and E-poly liners. Regenerex with ArCom and E-poly liners. Enrollment goal of 1000 patients 17 centers world-wide. 126 patients recruited so far.

37 16 patients followed for 6 month. 3 of 21 E-Poly RSA patients for 1 year.

38 Durasul Longevity

39 The contemporary bearings MoM, CoC and first generation highly x-linked polyethylene all have some, but different performance issues. The Antioxidant infused technology (E-Poly) seems to be a forgiving and viable formulation of highly cross-linked polyethylene.

40 Orthopaedic Biomechanics and Biomaterials Laboratory Massachusetts General Hospital