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Is OXINIUM really better?

In my last post [click here] I reviewed a 1988 scientific paper which raised a number of questions for me.

The last third of the Post looks at one of the new “wonder materials” – Oxinium (TM Smith & Nephew) and in the light of this last scientific article and the other literature I have read I am left wondering:

All forms of hip replacement have problems

– but what really interests me is that I have a Smith & Nephew Birmingham Spectron Cobalt Chrome Total Hip Replacement (THR) – which by the way is bloody painful as I write this – and I think that we all know the issues emerging with Cobalt Chrome – higher levels than normal in the blood & tissues, osteolysis (tissue damage) and bone resorption.

So metal-on-metal is not performing well if you have a DePuy THR – and for lucky low-percentile types like me – the Smith & Nephew Cobalt Chrome is just as nasty it seems…

So what are Smith & Nephew touting now … OXINIUM (Smith & Nephew Registered TM) – which is:

Oxidized Zirconium – which is ZIRCONIA...

Now, according to Wikepedia:

Zirconium dioxide (ZrO2), sometimes known as zirconia (not to be confused with zircon), is a white crystalline oxide of zirconium.

Now didn’t I read somewhere (above) that:

Since this wear was attributed to the zirconia particles… AND

zirconia particles produced marked activation of macrophages and an inflammatory reaction …

So I ask myself a very simple question – why would someone make an articulating surface (hip joint) which is effectively made of a metallic “sand paper” – surely one would have to expect wear – even though it is in theory “diamond hard”?

A few things stand out for me:

  1. Zirconium may well be bio-compatible like titanium – but according to the scientific paper above oxidised zirconium (zirconia) IS NOT…
  2. As the Zirconia in the ball joint of the THR wears, surely it will shed zirconia particles – these produced marked activation of macrophages and an inflammatory reaction… AND
  3. wear was attributed to the zirconia particles…
  4. AND… wear with Oxinium, while less, may lead to to more inflamatory reaction – less may produce more – will have to research the literature further to see what is said.

So call me a bloody skeptic, but we may well end up with yet another accident going somewhere to happen…

And you will note below:

Smith & Nephew say “excellent fracture toughness like cobalt chrome” – WELL, that answers another of my questions about S&N Birmingham Spectron Cobalt Chrome THR’s – they MUST have “heat treated” the cast Cobalt Chrome alloy as cast Cobalt Chrome according to the literature I have read is brittle – have a look at the post where I highlight the scientific study that shows – click here to go to it. And here is the Scientific Paper Click here.

AND when you heat-treat cast Cobalt Chrome, you decrease the carbide content –

“carbide content can be reduced from a volume percentage of seven down to 0.03.”

So as reduced carbide content reduces toughness, but gives more flexibility (less fractures), it also increases wear, and the rate of release of cobalt and chromium ions into the surrounding bone and tissue – leading to osteolysis, tissue and bone damage, bone resorption and many metabolic problems at higher levels.

So it seems safe to assume (may I?) that the Smith & Nephew Cobalt Chrome THR that I have has heat treated Cobalt Chrome – hence the cobalt chrome damage to my hip tissues and bone.

Note the earlier reference:

Co [i.e. Cobalt; my note] was toxic to osteoblast-like cell lines and inhibited the production of type-I collagen, osteocalcin and alkaline phosphatase

So cobalt is toxic to the very cells that produce new bone….

Here’s what Smith & Nephew have to say about OXINIUM:

What is the OXINIUM material?

OXINIUM oxidized zirconium is a metallic alloy with a ceramic surface that provides wear resistance without brittleness.

OXINIUM material combines the best of both metal and ceramics.

It is a metal, with excellent fracture toughness like cobalt chrome, (my underlining) but it has a ceramic surface that offers outstanding wear resistance.3

OXINIUM Profile
OXINIUM Profile

The ceramic is an enhanced surface that is part of the metal substrate rather than an external coating, making it very durable.

Zirconium: a biocompatible metallic element in the same family as titanium.

Zirconia: a ceramic compound, wear-resistant but brittle.

Zr-2.5Nb: a metallic alloy of zirconium, with niobium and oxygen for increased strength.

Quality Control for OXINIUM Components

Extensive research and development indicated four critical control points to ensure a consistent quality product, as follows:

  • Raw materials inspection
  • Pre-oxidization surface preparation
  • Oxidization process
  • Post-oxidization surface burnishing

All components undergo inspection to ensure that the ceramic oxide is uniform and the correct thickness. A non-destructive laser measurement technique provides a means for 100% quality assurance inspection of components.

References
3. M. Long, L. Riester, and G. Hunter, “Nano-hardness measurements of oxidized Zr-2.5Nb and various orthopaedic materials”, Trans. Soc. Biomaterials, 21, 1998, p. 528.

Wear in Total Joint Arthroplasty

Wear of polyethylene components has often been reported in TJA to be a primary cause of complications and failure. Retrieval analyses and published articles support that a high percentage of inserts and patellas develop a significant wear pattern clinically.
In THA, the reduction in friction and wear with the OXINIUM bearing coupling is significant because aseptic loosening is a leading cause of implant failure, and wear debris is the leading cause of aseptic loosening. While virtually all advanced bearing couplings produce nearly immeasurable wear, metal-on-metal couplings produce cobalt and chromium ions. Ceramic couplings risk fracture.

With OXINIUM femoral heads, low wear reduces the chances of aseptic loosening and may extend the life of the joint. The OXINIUM material may offer extended joint life through reduced wear and friction.

Oxidized Zirconium

OXINIUM Hip Implants

When choosing a hip implant, you may expect trade-offs with current bearing options:
  • Fracture (ceramic-on-ceramic)
  • Metal sensitivity (metal-on-metal)
  • More wear and osteolysis (cobalt chrome-on-polyethylene)

Only the OXINIUM-on-XLPE advanced bearing system delivers peak performance without compromise, making it ideal for your patients.If you’re tired of the trade-offs, rethink your options and you will find the answer is black and white.

Fracture

Method of producing OXINIUM heads

OXINIUM heads on XLPE liners: no fracture, chipping or squeaking The ceramic surface of OXINIUM heads is not a coating, so it cannot chip or flake. The original metal surface is transformed into a ceramic through thermal processing, providing you with the only unbreakable ceramic on the market that is not a coating.1,2,3

The ceramic surface of OXINIUM heads is integral with the metal alloy which allows OXINIUM heads to provide ceramic wear performance without the risk of fracture.2,4,5 Whether it is fracture, chipping or squeaking that you are concerned about, OXINIUM heads on XLPE liners address all of these concerns.

OXINIUM heads do not fracture | Ceramic heads can fracture

References

  1. Hunter, G., Dickinson, J., Herb, B., et al. (2005). Creation of oxidized zirconium orthopaedic implants. J. ATSM Int., 2 (7).
  2. Sheth, N., Lementowski, P., Hunter, G., Garino, J. (2008). Clinical Applications of Oxidized Zirconium. J. Surgical Orthopaedic Advances, 17(1).
  3. Hunter, G. (2001) Adhesion testing of oxidized zirconium. Trans. 27th Ann. Mtg. Soc. Biomaterials, Society for Biomaterials, Minneapolis, MN, 540.
  4. Hobbs, L., Rosen, V., Mangin, S., et al. (2005). Oxidation microstructures and interfaces in the oxidized zirconium knee. J. Appl. Ceram. Tech., (2), 221-246.
  5. Sprague, J., Salehi, A. Tsai S., et al., Mechanical behavior of zirconia, alumina, and oxidized zirconium modular heads. In ISTA 2003, vol. 2, edited by S. Brown, I. C Clarke, A. Gustafson, International Society for Technology in Arthroplasty, Birmingham, AL, 2004.
  6. Hallab, N. (2004). Lympohocyte transformation testing for quantifying metal-implant-related hypersensitivity responses. Dermatitis, 15 (2), 82-92.
  7. Kovacs, P., Davidson J., Chemical and electrochemical aspects of the biocompatibility of titanium and its alloys. In American Society for Testing and Materials: Medical Applications of Titanium and Its Alloys, pp. 163-178, edited by S. A. Brown, J.E. Lemons, ASTM STP 1272, American Society for Testing and Materials, West Conshohocken, PA 1996.
  8. Hallab, N., Merritt, K., Jacobs, J. (2001). Metal sensitivity in patients with orthopaedic implants. Journ. Bone Joint Surg., 83 (A), 428-436.
  9. M arek, M., Pawar, V., Tsai. S., et al. (2006). Galvanic corrosion evaluation of Zr-2.5Nb coupled with orthopaedic alloys. In Medical Device Materials, 3, (pp. 195-201). Materials Park, OH: R. Venugopalan, M. Wu, ASM International Edition.
  10. N asser, S., Mott, M., Wooley, P. (2006). A prospective comparison of ceramic and oxinium TKA components in metal hypersensitivity patients. Proceedings of the Annual Meeting of the American Academy of orthopaedic Surgeons, (pp. 194) San Diego, CA.
  11. Lhotka, C., Szekerea, T., Steffan, T., Zhubar, K., and Zweymuller, K. 2003). Four year study of cobalt and chromium blood levels in patients managed with two different metal on metal total hip replacements. J. Ortho Research, 21 (2), 189-195.

Metal Allergies

OXINIUM heads on XLPE liners: a hypoallergenic

Patients have drastically different tolerances to metal ions. Nickel allergy has been demonstrated in up to 20% of patients with well-functioning implants and up to 55% of patients with poorly functioning implants.

Metal sensitivity skin rash reaction to an orthopaedic implant

OXINIUM material has no detectable nickel content. Compared to the traditional metal used in hip implants, the zirconium and niobium contained in OXINIUM material are more biocompatible. This makes OXINIUM heads an appropriate choice for patients with metal sensitivities.7,8,9,10,11 Whether it’s metal sensitivity or metal ions you are concerned about, OXINIUM heads on XLPE liners address both of these issues.

Osteolysis

OXINIUM heads on XLPE liners: lower risk of osteolysis

Wear debris from roughened CoCr on XLPE | Wear debris from roughened OXINIUM on XLPE

Smith & Nephew XLPE acetabular liners produce less wear particles than other cross-linked polyethylenes.12,13,14 When combined with OXINIUM heads, wear debris is further reduced in comparison with standard CoCr heads.

Simulator results utilizing the active high demand patient profile demonstrate that OXINIUM heads outperform CoCr heads on XLPE. OXINIUM heads minimize the material-related risks associated with other advanced bearings, while meeting the requirements of active patients. Whether it is the demands of active patients or prosthesis longevity that you are concerned about, OXINIUM heads on XLPE liners are a great choice.

References

3 Hunter, G. (2001) Adhesion testing of oxidized zirconium. Trans. 27th Ann. Mtg. Soc. Biomaterials, Society for Biomaterials, Minneapolis, MN, 540.

12 Good, V., Ries, M., Barrack, Rl, et al. (2003). Reduced wear with oxidized zirconium femoral heads. J. Bone Joint Surg., 85 (A suppl 4) 105-110.

13 Ries, M., Scott, M., Jani, S. (2001). Relationship between gravimetric wear and particles generation in hip simulators: conventional compared with cross-linked polyethylene. J. Bone Joint Surg. Am., 83, S116-122.

14 Scott, M., Morrison, M., Mishra, S., Jani, S. (2002). A method to quantify wear particle volume using atomic force microscopy. ORS Transactions, 27, 132.

15 Smith & Nephew. (2008). Smith & Nephew (Internal Report). Parikh, et. al.

16 M .G. Li, Z.K. Zhou, D.J. Wood, S.M. Rohrl, J.L. Loppolo, and B. Nivbrandt. (2006) Low wear with high-cross linked polyethylene especially in combination with Oxinium heads. A RSA evaluation. Trans. Orthop. Res. Soc., 31, 643.

 

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