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The Bone & Joint Journal
Vol. 99-B, Issue 10 | Pages 1304 - 1312
1 Oct 2017
Langton DJ Sidaginamale RP Joyce TJ Meek RD Bowsher JG Deehan D Nargol AVF Holland JP

Aims

We sought to determine whether cobalt-chromium alloy (CoCr) femoral stem tapers (trunnions) wear more than titanium (Ti) alloy stem tapers (trunnions) when used in a large diameter (LD) metal-on-metal (MoM) hip arthroplasty system.

Patients and Methods

We performed explant analysis using validated methodology to determine the volumetric material loss at the taper surfaces of explanted LD CoCr MoM hip arthroplasties used with either a Ti alloy (n = 28) or CoCr femoral stem (n = 21). Only 12/14 taper constructs with a rough male taper surface and a nominal included angle close to 5.666° were included. Multiple regression modelling was undertaken using taper angle, taper roughness, bearing diameter (horizontal lever arm) as independent variables. Material loss was mapped using a coordinate measuring machine, profilometry and scanning electron microscopy.


Bone & Joint Research
Vol. 3, Issue 3 | Pages 60 - 68
1 Mar 2014
Langton DJ Sidaginamale RP Holland JP Deehan D Joyce TJ Nargol AVF Meek RD Lord JK

Objectives

Wear debris released from bearing surfaces has been shown to provoke negative immune responses in the recipient. Excessive wear has been linked to early failure of prostheses. Analysis using coordinate measuring machines (CMMs) can provide estimates of total volumetric material loss of explanted prostheses and can help to understand device failure. The accuracy of volumetric testing has been debated, with some investigators stating that only protocols involving hundreds of thousands of measurement points are sufficient. We looked to examine this assumption and to apply the findings to the clinical arena.

Methods

We examined the effects on the calculated material loss from a ceramic femoral head when different CMM scanning parameters were used. Calculated wear volumes were compared with gold standard gravimetric tests in a blinded study.