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The effect of diamond like carbon coating on fretting corrosion and wear at the modular head-stem junction of metal on metal total hip replacements

Anna Panagiotidou1, 2*, Jayantilal M. Meswania1*, Osman Khabab1*, Alister Hart1, 3, John Skinner1, 3*, Fares Haddad2* and Gordon Blunn1*
  • 1 UCL, Institute of Orthopaedics, United Kingdom
  • 2 University College Hospital, United Kingdom
  • 3 Royal National Orthopaedic Hospital, United Kingdom

Introduction: Large head metal-on-metal retrieval studies have indicated that a significant amount of metal wear is directly attributable to the modular head-neck interface. Recent reports about the wear at this interface from metal on plastic THRs have been published. Release of metal ions and debris from this junction is attributed to mechanically assisted crevice corrosion (MACC). Galvanic coupling between cobalt chrome and titanium alloys may also contribute to metal ion release at this junction. Diamond-like carbon (DLC) is a very promising thin coating in this context because it is extremely hard, chemically inert, non-conducting and wear resistant. The aim of this study is to investigate if a coating of DLC on the surface of the male taper can reduce MACC of the cobalt chrome female taper.  

Methods: Neck tapers were manufactured to a single specification (average Rz=16.01µm, Ra=3.98µm). Three Ti-6Al-4V alloy tapers were coated with DLC by plasma enhanced chemical vapour deposition. These tapers were assembled using a standard impaction force of 4kN in accordance with ASTM F1875-98.  3 non-coated tapers were similarly impacted.  The surface profile of both female and male tapers were measured using a Talyrond 365 roundness machine with 180 traces 2O apart in order to provide a baseline volumetric measurement of the taper surface.   The tapers were enclosed in individual chambers orientated at head/neck angle of 1350. Components were immersed in 10% bovine calf serum diluted with Phosphate Buffered Saline (PBS) solution with pH 7.4 200C±10C. The femoral heads of the 6 assembly’s were cyclically loaded between 300N to 2.3kN using a sinusoidal wave-form at 1 Hz. Measurement of fretting current during for both coated and uncoated combinations was carried out during long-term cyclic loading for10 million cycles. After 10 million cycles the tapers were disassembled by sectioning through the centre of the head using a diamond saw thus preventing damage during disassembly. Light microscopy and scanning electron microscopy (SEM) of the component surfaces allowed assessment of surface deformation, crevice and pitting corrosion post in-vitro simulation. Statistical comparison of the mean fretting currents was made using a Mann Whitney U test.

Results: The fretting currents for the all components reduced upon cyclic loading.  The mean fretting current for the DLC components remain low between 2 and 10 million cycles, whereas the current for the non-coated components increased after 3 million cycles and remained significantly (p=<0.05) higher throughout the reminder of the test (figure 1). At 10 million cycles the fretting current was over 2 times lower for DLC coated components. Examination of the titanium male tapers after the 10 million-cycle wear test showed that DCL remained intact. The female tapers adjacent to the DLC visually showed less damage that those adjacent to non-coated titanium tapers (figure 2). Analysis of the surface profiles of the female tapers showed that there were greater amounts of imprinting seen adjacent to the non-coated titanium spigots. There was also a much larger build up of corrosion deposits on these female tapers.

Conclusion: In this study we have shown that DLC coating of Ti-6Al-4V alloy neck tapers show a reduction in the fretting current compared to non-coated tapers  indicating a greater resistance to MACC.  This was confirmed by the specimens after a 10 million cyclic test which showed greater MACC on the   female taper adjacent to the  non coated titanium alloy spigots.

Keywords: corrosion, Implant, wear

Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.

Presentation Type: General Session Oral

Topic: Biomaterials in musculoskeletal orthopeadics and tissues

Citation: Panagiotidou A, Meswania JM, Khabab O, Hart A, Skinner J, Haddad F and Blunn G (2016). The effect of diamond like carbon coating on fretting corrosion and wear at the modular head-stem junction of metal on metal total hip replacements. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01094

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Received: 27 Mar 2016; Published Online: 30 Mar 2016.

* Correspondence:
Dr. Anna Panagiotidou, UCL, Institute of Orthopaedics, London, United Kingdom, panagiotidou@btinternet.com
Dr. Jayantilal M Meswania, UCL, Institute of Orthopaedics, London, United Kingdom, j.meswania@ucl.ac.uk
Dr. Osman Khabab, UCL, Institute of Orthopaedics, London, United Kingdom, k.z.osman@googlemail.com
Dr. John Skinner, UCL, Institute of Orthopaedics, London, United Kingdom, john.skinner@ucl.ac.uk
Dr. Fares Haddad, University College Hospital, London, United Kingdom, fsh@fareshaddad.net
Dr. Gordon Blunn, UCL, Institute of Orthopaedics, London, United Kingdom, g.blunn@ucl.ac.uk