We have encountered patients who developed large joint fluid collections with massive elevations in chromium (Cr) and cobalt (Co) concentrations following metal-on-metal (MoM) hip arthroplasties. In some cases, retrieval analysis determined that these ion concentrations could not be explained simply by the wear rates of the components. We hypothesized that these effects may be associated with aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). We examined the influence of the ALVAL grade on synovial fluid Co and Cr concentrations following adjustment for patient and device variables, including volumetric wear rates. Initially restricting the analysis to include only patients with one MoM hip resurfacing device, we performed multiple regression analyses of prospectively collected data. We then repeated the same statistical approach using results from a larger cohort with different MoM designs, including total hip arthroplasties.Objectives
Patients 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
We wished to investigate the influence of metal debris exposure
on the subsequent immune response and resulting soft-tissue injury
following metal-on-metal (MoM) hip arthroplasty. Some reports have
suggested that debris generated from the head-neck taper junction
is more destructive than equivalent doses from metal bearing surfaces. We investigated the influence of the source and volume of metal
debris on chromium (Cr) and cobalt (Co) concentrations in corresponding
blood and hip synovial fluid samples and the observed agglomerated
particle sizes in excised tissues using multiple regression analysis
of prospectively collected data. A total of 199 explanted MoM hips
(177 patients; 132 hips female) were analysed to determine rates
of volumetric wear at the bearing surfaces and taper junctions. Aims
Patients and Methods
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. 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. Objectives
Methods
The aims of this piece of work were to: 1) record the background
concentrations of blood chromium (Cr) and cobalt (Co) concentrations
in a large group of subjects; 2) to compare blood/serum Cr and Co
concentrations with retrieved metal-on-metal (MoM) hip resurfacings;
3) to examine the distribution of Co and Cr in the serum and whole
blood of patients with MoM hip arthroplasties; and 4) to further
understand the partitioning of metal ions between the serum and
whole blood fractions. A total of 3042 blood samples donated to the local transfusion
centre were analysed to record Co and Cr concentrations. Also, 91
hip resurfacing devices from patients who had given pre-revision
blood/serum samples for metal ion analysis underwent volumetric
wear assessment using a coordinate measuring machine. Linear regression analysis
was carried out and receiver operating characteristic curves were
constructed to assess the reliability of metal ions to identify
abnormally wearing implants. The relationship between serum and
whole blood concentrations of Cr and Co in 1048 patients was analysed
using Bland-Altman charts. This relationship was further investigated
in an Objectives
Methods
To evaluate the complications following percutaneous balloon kyphoplasty and assess the advantage of introducing eggshell technique. We performed 138 Balloon kyphoplasty procedures in 85 patients during august 2007 to march 2010. Data was collected and analyzed in all these cases. Gender distribution was 60 females and 25 males. Age distribution was 33 to 85 years, with an average age of 67.4 years. Indications of surgery were vertebral fractures due to osteoporosis in 81% of the procedures, trauma in 13% and malignancy in 6%. The most common vertebral levels of the kyphoplasty were at T12 in 32 procedures (23%) and L1 in 28 procedures (20%). Eggshell technique was introduced in 2009 where technical problems were encountered during cementing process. All patients had reduced pain levels, which was assessed by visual analog score. The average length of hospital stay was 2.5 days. Complications were 9 (6.5%) cement leaks (all within one cm from the vertebral body) in procedures performed before the introduction of eggshell technique and no cement leak following the introduction of eggshell technique, 5 (3.6%) fresh fractures, 2 (1.4%) intra-operative fractures and 1 (0.73%) rupture of balloon. There were no complications of cord compression, motor deficit, infection, allergy to cement or pulmonary embolism noted. 30-day mortality rate was zero.Purpose
Methods and Results
To elucidate the efficacy of carrying out additional vertebral biopsy procedure during percutaneous balloon kyphoplasty as a tool in determining malignant etiology. We performed 138 percutaneous balloon kyphoplasty procedures in 85 patients during august 2007 to march 2010. Gender distribution was 25 males and 60 females. Age distribution was 33 to 85 years, with an average age of 67.4 years. The senior surgeon attempted vertebral biopsy during percutaneous balloon kyphoplasty procedure only when there was a clinical/operative suspicion of malignancy. We did not routinely biopsy all vertebrae, as this would mean additional procedure adding to the cost and operating time. In 42 procedures vertebral biopsy was attempted, of which 5 samples were reported as insufficient specimen. 37 biopsies (88%) were successfully analyzed. 3 biopsies (8.1%) were positive for malignancy. There were no complications encountered in the cases where additional biopsy procedure was carried out.Purpose
Methods and Results
