Imperial College London
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Dr Pramod K. Puthumanapully

Central Faculty, Advancement

Head of Development Faculty of Medicine
 
 
 
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Contact

 

+44 (0)20 7594 3299p.puthumanapully Website

 
 
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Location

 

AdvancementFaculty BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Puthumanapully:2013:10.1302/1358-992X.95BSUPP_34.ISTA2013-288,
author = {Puthumanapully, PK and Stewart, M and Browne, M and Dickinson, A},
doi = {10.1302/1358-992X.95BSUPP_34.ISTA2013-288},
journal = {Orthopaedic Proceedings},
pages = {288--288},
title = {Modular Junction Testing of Large Diameter Metal on Metal Hip Replacements: A Pilot Study},
url = {http://dx.doi.org/10.1302/1358-992X.95BSUPP_34.ISTA2013-288},
volume = {95-B},
year = {2013}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - IntroductionFatigue and wear at the head/stem modular junction of large diameter total hip replacements can be exacerbated as a result of the increase in frictional torque. In vivo, a ?toggling,? anterior-posterior (A-P) movement of the head taper on the trunnion may facilitate corrosion in the presence of physiological fluids, leading to increased metal ion release. Clinically, metal ion release has been linked to the formation of pseudo tumours and tissue necrosis [1].AimsIn this investigation, a large diameter metal on metal THR was tested on a rig designed to recreate the toggling motion at the head/stem junction. Post-test analyses are conducted to look for evidence of mechanical and corrosive damage.Methods and MaterialsA 58 mm diameter metal head (12/14 taper) was assembled onto a sectioned Freeman stem affixed to custom designed rig that enabled both, axial loads and a frictional torque (for the AP toggle load) about the rotation of the femoral head to be applied as shown in Figure 1. A linear variable differential transformer (LVDT), which had a minimum resolution of 0.5 microns, was positioned in contact with the neck directly under the modular head to track A-P movements at the junction. An axial load of 150N with toggle loads varying between 100 (± 50N) and 200N (± 50N) at 1 Hz were run on 4 taper assemblies, 2 dry and 2 wet (incorporating a physiological fluid at the junction) between 400,000 and 600,000 cycles. Movement at the junction was recorded, followed by visual inspection and RedLux? surface profile analysis of the taper and trunnion.Results and ConclusionThe LVDT could successfully record movement at the junction. Initially (?1000 cycles), the movement at the junction was found to be variable and between 5?10 microns, which can be attributed to the taper ?bedding-in? on to the trunnion. The movement was then found to steadily increase before stabilising. The dry tapers recorded motion ranging between 5?15 microns, and between 10?2
AU  - Puthumanapully,PK
AU  - Stewart,M
AU  - Browne,M
AU  - Dickinson,A
DO  - 10.1302/1358-992X.95BSUPP_34.ISTA2013-288
EP  - 288
PY  - 2013///
SN  - 1358-992X
SP  - 288
TI  - Modular Junction Testing of Large Diameter Metal on Metal Hip Replacements: A Pilot Study
T2  - Orthopaedic Proceedings
UR  - http://dx.doi.org/10.1302/1358-992X.95BSUPP_34.ISTA2013-288
UR  - https://online.boneandjoint.org.uk/doi/abs/10.1302/1358-992X.95BSUPP_34.ISTA2013-288
VL  - 95-B
ER  -
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