Serum metal ion levels following spinal deformity surgery: a case-control study of 182 individuals

The aim of this study is to evaluate the levels of chromium (Cr), cobalt (Co), and titanium (Ti) after instrumented fusion for scoliosis.

Serum samples were collected at median 2.24 (range 0.1-38.8) years after fusion surgery for scoliosis in 91 individuals, of which 71 had been treated with steel implants and 20 with titanium implants. 91 sex and age-matched non-surgically treated individuals with scoliosis were used as controls. Levels of Cr, Co, and Ti were measured.

In the 91 surgically treated individuals median levels of Cr were 0.54 µg/l vs 0 µg/l in the 91 controls, p < 0.001. Corresponding results for Co were 0.29 µg/l vs. 0.24 µg/l, p = 0.19, and for Ti were 0 µg/l vs. 0 µg/l, p < 0.001. In the individuals with steel implants and their corresponding controls median Cr levels were 0.63 µg/l vs. 0.00 µg/l, p < 0.001 and Co levels 0.27 µg/l vs. 0.23 µg/l, p = 0.36. No Ti was detected. In the individuals with titanium implants, median Cr levels were 0 µg/l vs. 0 µg/l in their corresponding controls, p = 0.38. Corresponding results for Co was 0.39 µg/l vs. 0.31 µg/l, p = 0.27 and for Ti 4.31 µg/l vs. 0 µg/l, p < 0.001. In the individuals with steel implants a negative correlation between implant time in situ and levels of Cr was found ([Formula: see text] = - 0.52, p < 0.001) but not with Co ([Formula: see text] = - 0.14, p = 0.23). Ti was not detected. In the individuals with titanium implants, there was no correlation between implant time in situ and levels of Cr ([Formula: see text] = 0.36, p = 0.12), Co ([Formula: see text] = - 0.12, p = 0.60) or Ti ([Formula: see text] = 0.22, p = 0.35).

The use of stainless steel and titanium implants in spinal fusion surgery is associated with elevated metal ion concentrations several years after surgery.