P69
METALLOSIS AND CHRONIC KIDNEY DISEASE: CONSIDERATIONS FOR A
NEPHROLOGIST
Balasubramaniam G*, Khang S*, Lusty P#, Greer S#, Almond M*
*Department of Renal Medicine, Southend General Hospital
#
Department of Orthopaedics, Southend General Hospital
INTRODUCTION: Most metal hip replacements nowadays are made up of chromium and cobolt
alloys. Corrosion usually leads to high levels of these trace elements in blood which is primarily
excreted through the kidneys and can cause tubular damage. Metallosis is a complication that is
characterised by a localised inflammation and fibrosis, with very high circulating levels of chromium
and cobolt. Patients with renal failure are felt to be at risk of accumulation with subsequent systemic
and toxicity. Furthermore, patients with high circulating levels may be at risk of chronic kidney
disease. Much is known about this condition in the orthopaedic community but there is not much
experience reported in the renal literature.
METHODS: We report a case of metallosis in a haemodialysis patient after hip replacement. We
then looked at all the patients who had a metal on metal joint replacement at out centre and undertook
a cross-sectional survey of their metal levels and renal function. Whole blood assays of chromium and
cobolt were done at a reference laboratory at varying time after the joint replacement.
RESULTS
Case Report
We report a 36-year old male who developed bilateral avascular necrosis of both hips after prolonged
periods of high dose steroids following transplantation. His transplant eventually failed and he was
back on dialysis. He initially had a left hip replacement, followed by a right hip replacement. Both his
hip replacements were complicated by ongoing pain and inflammation, requiring local steroid
injections and multiple revisions. Histology from one revision surgery showed changes consistent
with metallosis. Serum levels of cobolt and chromium were not elevated above the expert advisory
recommendation for metallosis.
Cross-sectional study
There were 52 patients (29 M) from our centre who had metal on metal joint prosthesis from 1/1/4 to
1/5/12. The mean age at surgery was 56 (range 38 – 91), and the mean egfr was 90mls/min/1.73m2
(range 49-135). 24 patients had CKD 4, 1 had CKD 3. 45 patients had a Chromium and Cobolt level
measured at one point after surgery. One patient had high levels as they had a double metal on metal
prosthesis. Of the remaining 44 patient; average blood chromium and cobolt levels were 58.0nmol/l
(range 10.7 – 223) and 47.1nmol/l (range 3.1-368) respectively. Average follow-up was 36 months;
mean egfr at follow up was 90mls/min/1.73m2 (range 40-130). The handful of patients with higher
than recommended levels in their blood did not have worse kidney function at follow-up.
CONCLUSION: Our case suggests that haemodialysis patients may be protected from high
chromium and cobolt levels by removal from dialysis. Most patients in our cross sectional survey had
good kidney function at the time of surgery, and the levels of chromium and cobolt after surgery were
below the expert advisory recommendation for metallosis (chromium 134nmol/l and cobolt
119nmol/l). Kidney function was preserved at three years suggesting that these levels of chromium
and cobolt do not pose a risk for worsening kidney function in the medium term follow-up.
Unfortunately, our survey did not consist of many patients with moderate to severe kidney disease and
we cannot comment whether this may pose a risk for higher levels of metals in the blood and
predispose to toxicity.