Serum metal ion levels in adolescent idiopathic scoliosis (AIS) patients 25 years after treated with Harrington rod instrumentation or bracing

Introduction Surgical instrumentation in children with adolescent idiopathic scoliosis (AIS) is performed early in life and the implants are left in situ for the rest of the patient’s life. Concern has been raised regarding persistent elevated levels of serum metal ions, but only a few studies on the topic have been published. The aim of this study was to compare the levels of serum metal ions in patients with AIS treated with either Harrington rod instrumentation or bracing. Materials and methods AIS patients treated with Boston brace (BB) or posterior spinal fusion with Harrington rod instrumentation (HR) from 1983 to 1990 were requested to return to clinic. One hundred fifty-nine (73%) of 219 patients were available for follow-up of whom 115 agreed to have a blood draw. Results The proportion of patients who agreed to have a blood draw were similar in the BB (48 of 100, 48%) and HR (67 of 115, 60%, p = 0.085) groups. None of the surgical patients had their implants removed; mean age at follow-up (BB: 43.2 years vs HR: 43.5 years, p = 0.566) and mean length of follow-up (BB: 26.5 years vs HR: 24.5 years). Mean chromium serum levels were similar between the BB (2.7 nmol/L) and the HR (2.9 nmol/L, p = 0.827). Mean Cobalt serum levels were also similar between the BB (2.6 nmol/L) and the HR (2.8 nmol/L, p = 0.200). Conclusion Serum metal ions were similar in AIS patients treated with bracing or Harrington rod instrumentation 25 years after initiation of treatment.