Serum Titanium Levels Remain Elevated 6 Years and Beyond From Spinal Instrumentation in Children.

BACKGROUND

Paediatric spinal implants are known to cause circulating metal ions. A previous prospective study by the authors demonstrated elevated chromium, cobalt, nickel, and especially persistence of titanium serum levels at a median of 5.4 times baseline level.

METHODS

A continuation of prospective study of children undergoing spinal deformity surgery with repeated testing for circulating metal ions including preoperative levels as controls. Thirty-four of 56 participants returned beyond 6 years from surgery for testing for circulating metal ions using high-resolution inductively coupled plasma mass spectrometry. Linear mixed effects models adjusting for repeated measurements over time were used to analyse titanium, chromium, cobalt, and nickel serum levels.

RESULTS

Median titanium levels at 6 years decreased significantly to 0.46 times that of 2-year levels (95% CI: 0.32-0.67, P <0.001); however, they remained 2.40 times higher compared with the presurgery control levels (95% CI: 1.47-3.92, P <0.001). In comparison, median chromium levels at 6 years were significantly increased from 2 years (1.45 times) but were not significantly different to baseline (1.13 times). Cobalt levels at 6 years remained significantly higher than baseline (1.32 times), but also decreased significantly compared with 2-year levels (0.76 times). Nickel levels at 6 years did not differ significantly from baseline or from 2-year levels.

CONCLUSIONS

Titanium remains raised at beyond 6 years from spinal instrumentation in children. The effects on a person's health through deposition in solid organs including the brain or on the offspring of persons with spinal instrumentation remains unclear. Curiously, chromium levels increased at 6-year sampling in "all titanium" constructs which may be explained by metallurgical irregularities.

LEVEL OF EVIDENCE: Level II.