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PEEK (Polyether-ether-ketone) Based Cervical Total Disc Arthroplasty: Contact Stress and Lubrication Analysis.

Xin H, Shepherd D, Dearn K - Open Biomed Eng J (2012)

Bottom Line: The NuNec(®) cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint.The peak contact stress and the minimum film thickness between the bearing surfaces were then determined, as the radial clearance or lubricant was varied.The obtained results show that under 150 N loading, the peak contact stress was in the range 5.9 - 32.1 MPa, well below the yield and fatigue strength of PEEK; the calculated minimum film thickness ranged from 0 to 0.042 µm and the corresponding lambda ratio range was from 0 to 0.052.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.

ABSTRACT
This paper presents a theoretical analysis of the maximum contact stress and the lubrication regimes for PEEK (Polyether-ether-ketone) based self-mating cervical total disc arthroplasty. The NuNec(®) cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint. A non-adhesion Hertzian contact model and elastohydrodynamic lubrication theory were used to predict the maximum contact stress and the minimum film thickness, respectively. The peak contact stress and the minimum film thickness between the bearing surfaces were then determined, as the radial clearance or lubricant was varied. The obtained results show that under 150 N loading, the peak contact stress was in the range 5.9 - 32.1 MPa, well below the yield and fatigue strength of PEEK; the calculated minimum film thickness ranged from 0 to 0.042 µm and the corresponding lambda ratio range was from 0 to 0.052. This indicates that the PEEK based cervical disc arthroplasty will operate under a boundary lubrication regime, within the natural angular velocity range of the cervical spine.

No MeSH data available.


Related in: MedlinePlus

a) Variation of minimum film thickness with angularvelocity; b) Variation of Lambda ratio with angular velocity. Eachfigure is plotted for a cervical disc arthroplasty at a radial clearancevalue of 0.7 mm, under 150 N load, using two different lubricantsbovine serum and interstitial fluid.
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Figure 5: a) Variation of minimum film thickness with angularvelocity; b) Variation of Lambda ratio with angular velocity. Eachfigure is plotted for a cervical disc arthroplasty at a radial clearancevalue of 0.7 mm, under 150 N load, using two different lubricantsbovine serum and interstitial fluid.

Mentions: Fig. (5a & b) show the variation of minimum film thickness and lambda ratio, respectively, when different lubricants are employed. The minimum film thickness can be enhanced by incorporating a more viscous lubricant; the lambda ratio can be increased in a similar manner. In spite of this, the lubrication regime is still boundary lubrication, regardless of the lubricant used.


PEEK (Polyether-ether-ketone) Based Cervical Total Disc Arthroplasty: Contact Stress and Lubrication Analysis.

Xin H, Shepherd D, Dearn K - Open Biomed Eng J (2012)

a) Variation of minimum film thickness with angularvelocity; b) Variation of Lambda ratio with angular velocity. Eachfigure is plotted for a cervical disc arthroplasty at a radial clearancevalue of 0.7 mm, under 150 N load, using two different lubricantsbovine serum and interstitial fluid.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3367298&req=5

Figure 5: a) Variation of minimum film thickness with angularvelocity; b) Variation of Lambda ratio with angular velocity. Eachfigure is plotted for a cervical disc arthroplasty at a radial clearancevalue of 0.7 mm, under 150 N load, using two different lubricantsbovine serum and interstitial fluid.
Mentions: Fig. (5a & b) show the variation of minimum film thickness and lambda ratio, respectively, when different lubricants are employed. The minimum film thickness can be enhanced by incorporating a more viscous lubricant; the lambda ratio can be increased in a similar manner. In spite of this, the lubrication regime is still boundary lubrication, regardless of the lubricant used.

Bottom Line: The NuNec(®) cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint.The peak contact stress and the minimum film thickness between the bearing surfaces were then determined, as the radial clearance or lubricant was varied.The obtained results show that under 150 N loading, the peak contact stress was in the range 5.9 - 32.1 MPa, well below the yield and fatigue strength of PEEK; the calculated minimum film thickness ranged from 0 to 0.042 µm and the corresponding lambda ratio range was from 0 to 0.052.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.

ABSTRACT
This paper presents a theoretical analysis of the maximum contact stress and the lubrication regimes for PEEK (Polyether-ether-ketone) based self-mating cervical total disc arthroplasty. The NuNec(®) cervical disc arthroplasty system was chosen as the study object, which was then analytically modelled as a ball on socket joint. A non-adhesion Hertzian contact model and elastohydrodynamic lubrication theory were used to predict the maximum contact stress and the minimum film thickness, respectively. The peak contact stress and the minimum film thickness between the bearing surfaces were then determined, as the radial clearance or lubricant was varied. The obtained results show that under 150 N loading, the peak contact stress was in the range 5.9 - 32.1 MPa, well below the yield and fatigue strength of PEEK; the calculated minimum film thickness ranged from 0 to 0.042 µm and the corresponding lambda ratio range was from 0 to 0.052. This indicates that the PEEK based cervical disc arthroplasty will operate under a boundary lubrication regime, within the natural angular velocity range of the cervical spine.

No MeSH data available.


Related in: MedlinePlus