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· DOS Abstracts
Metal-on-metal wear in Children with Growth Rod
Instrumentation (GR) in Early Onset Scoliosis
Simon Toftgaard Skov, Jan Hendrik Duedal Rölfing, Haisheng Li, Ebbe Stender
Hansen, Cody Bünger
Orthopaedic Research Lab., Århus Universitetshospital
Background:
Wear and corrosion of metal implants are of great concern espe-
cially in MoM hip implants. Evidence of MoM wear in spinal implants in children
is sparse.
Purpose / Aim of Study:
To determine metal ion levels in children with cobalt-
chromium/titanium GR undergoing interval lengthening.
Materials and Methods:
Cross-sectional study in 34 patients including 8 chil-
dren prior to surgery, median age 11.0 (range 3.3-15.8) were included during
1.7 years. Standardized venous blood samples were collected at median 2.6 (0-
10) years post index surgery. Contamination-free consensus guidelines were
followed. Blinded analysis was performed for serum chromium(Cr), cobalt(Co),
molybdenum(Mo), titanium(Ti), aluminium(Al), vanadium(V) using high- reso-
lution mass spectrometry at a certified laboratory.
Findings / Results:
The Cr levels at index were median 1.9 ppb (0.5-10) vs.
1.1 ppb (0.5-80) during elongation, p=0.46. Cr levels exceeded the 7 ppb
warning threshold given by MHRA
(www.gov.uk) in 8 out of 34 children be-
tween 2.4-3.4 years post index surgery. All 8 Cr levels returned below thresh-
old within the following year, despite presence of metal debris in most operated
patients. Co levels increased from median 0.2 (0-0.4) ppb to 0.5 (0-2.6) ppb,
p<0.0001. The median Ti levels at index was below the detection limit of 1 ppb
(max 3.4) vs. 10.6 ppb (1.1-48.4) during elongation, p<0.001. Al, Mo, V levels
did not differ.
Conclusions:
8 patients had transient Cr levels above the warning threshold.
All returned below threshold within the next year. The children with elevated ion
levels did not differ clinically from the remaining group. Minimizing and moni-
toring iatrogenic metal ion exposure in these children is important due to the
increased risk of genotoxicity and mutagenicity. This study could not confirm an
increased risk.
No conflicts of interest reported
47.