Dual mobility implants in total hip arthroplasty are designed to increase the functional head size, thus decreasing the potential for dislocation. Modular dual mobility (MDM) implants incorporate a metal liner (e.g. cobalt-chromium alloy) in a metal shell (e.g. titanium alloy), raising concern for mechanically assisted crevice corrosion at the modular liner-shell connection. We sought to examine fretting and corrosion on MDM liners, to analyze the corrosion products, and to examine histologically the periprosthetic tissues. A total of 60 retrieved liners were subjectively scored for fretting and corrosion. The corrosion products from the three most severely corroded implants were removed from the implant surface, imaged using scanning electron microscopy, and analyzed using Fourier-transform infrared spectroscopy.Aims
Methods
There are limited published data detailing the volumetric material loss from tapers of conventional metal-on-polyethylene (MoP) total hip arthroplasties (THAs). Our aim was to address this by comparing the taper wear rates measured in an explanted cohort of the widely used Exeter THA with those measured in a group of metal-on-metal (MoM) THAs. We examined an existing retrieval database to identify all Exeter V40 and Universal MoP THAs. Volumetric wear analysis of the taper surfaces was conducted using previously validated methodology. These values were compared with those obtained from a series of MoM THAs using non-parametric statistical methodology. A number of patient and device variables were accounted for using multiple regression modelling.Aims
Patients and Methods
To present a surgically relevant update of trunnionosis. Systematic review performed April 2017.Aims
Materials and Methods
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. 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.Aims
Patients and Methods
The inherent challenges of total hip replacement
(THR) in children include the choice of implant for the often atypical
anatomical morphology, its fixation to an immature growing skeleton
and the bearing surface employed to achieve a successful long-term
result. We report the medium-term results of 52 consecutive uncemented
THRs undertaken in
35 paediatric patients with juvenile idiopathic arthritis. The mean
age at the time of surgery was 14.4 years (10 to 16). The median
follow-up was 10.5 years (6 to 15). During the study period 13 THRs
underwent revision surgery. With revision as an endpoint, subgroup
analysis revealed 100% survival of the 23 ceramic-on-ceramic THRs
and 55% (16 of 29) of the metal- or ceramic-on-polyethylene. This
resulted in 94% (95% CI 77.8 to 98.4) survivorship of the femoral
component and 62% (95% CI 41.0 to 78.0) of the acetabular component.
Revision of the acetabular component for wear and osteolysis were
the most common reasons for failure accounting for 11 of the 13
revisions. The success seen in patients with a ceramic-on-ceramic articulation
seems to indicate that this implant strategy has the potential to
make a major difference to the long-term outcome in this difficult
group of patients.
