Head Taper Corrosion Causing Head Bottoming Out and Consecutive Gross Stem Taper Failure in Total Hip Arthroplasty

Content Provider	Scilit
Author	Morlock, Michael M. Dickinson, Emilie C. Günther, Klaus-Peter Bünte, Dennis Polster, Valerie
Copyright Year	2018
Description	Journal: The Journal of Arthroplasty Taper corrosion in Total Hip Arthroplasty for bearings with metal heads against polyethylene has developed from an anecdotal observation to a clinical problem. Increased taper wear and even gross taper failure have been reported for one particular design. It is hypothesized that corrosion of the female head taper results in taper widening, allowing the CoCr head to turn on the stem and wear down the softer titanium alloy by abrasive wear, ultimately causing failure. The purpose of this study was to investigate the time course of this process and the general role of taper dimensions and material in this problem. Retrieved CoCr-alloy heads (n=30, LFIT, Stryker) and TMZF stems (n=10, Accolade I, Stryker) were available for analysis. Taper material loss was determined using 3D-coordinate measurements and scanning. The pristine tip clearance between head and stem was analytically determined. The influence of taper material and taper size on taper deformation and micromotion was investigated using a Finite Element Model. Material loss at the head taper increased with time in situ up to a volume of 20.8 mm³ (p<0.001). A mean linear material loss above 76 μm at the head taper was analytically confirmed to result in bottoming out, which was observed in 12 heads. The FE calculations showed significantly larger deformations and micromotions for a small 11/13 TMZF taper combined with a distinctly different micromotion pattern compared to other materials and taper designs. A 11/13 TMZF taper design with 36mm head diameters bears a higher risk for corrosion than larger tapers made from stiffer materials. Failures of this combination are not restricted to the head sizes included in the recall. Patients with this implant combination should be closely monitored.
Related Links	https://tore.tuhh.de/bitstream/11420/1872/1/morlock_mm_2018_head_taper_corrosion__accepted.pdf http://www.arthroplastyjournal.org/article/S0883540318306600/pdf
Ending Page	3590
Page Count	10
Starting Page	3581
ISSN	08835403
e-ISSN	15328406
DOI	10.1016/j.arth.2018.07.017
Journal	The Journal of Arthroplasty
Issue Number	11
Volume Number	33
Language	English
Publisher	Elsevier BV
Publisher Date	2018-11-01
Access Restriction	Open
Subject Keyword	Journal: The Journal of Arthroplasty Taper Corrosion Gross Taper Failure Head Size
Content Type	Text
Resource Type	Article
Subject	Orthopedics and Sports Medicine