title: Metal concentrations in the serum and hair of patients with titanium alloy spinal implants.
abstract: METHODS
  A retrospective study of serum and hair metal concentrations in patients with titanium alloy spinal implants was performed.
  
  
  OBJECTIVE
  To determine the incidence and possible causes of abnormal metal concentrations.
  
  
  BACKGROUND
  Several studies have demonstrated that metal debris are present in the tissues surrounding titanium alloy spinal implants. However, few studies suggest that metals dissolve, circulate in the body fluid, and accumulate in remote organs.
  
  
  METHODS
  Titanium, aluminum, and vanadium concentrations in serum and hair were measured after surgery in 46 patients with titanium alloy spinal implants (12 patients in the implant failure group and 34 patients in the no implant failure group) and 20 patients without spinal implants (control group). All the subjects were examined again 1 year after the first examination or implant removal.
  
  
  RESULTS
  Of the 46 patients with titanium alloy spinal implants, 16 patients (34.8%) exhibited abnormal serum metal concentrations and 11 patients (23.9%) exhibited abnormal hair metal concentrations. In the control group, three patients (15%) exhibited only abnormal serum and metal aluminum concentrations at the first examination. In both of the two patients who exhibited abnormal serum titanium concentrations and then had their spinal implants removed, the serum and hair titanium levels decreased to beneath the reference value limit in 1 year after the removal. Comparison of the implant failure and no implant failure groups showed no significant differences in the incidence of abnormal serum concentrations of titanium, aluminum, or both metals. Therefore, serum metal concentrations did not seem to be a useful indicator of hardware loosening or implant failure.
  
  
  CONCLUSIONS
  Approximately one third of patients with titanium alloy spinal implants exhibited abnormal serum or hair metal concentrations at a mean time of mean 5.1 years after surgery. Titanium or aluminum may travel to distant organs after dissolution of metals from the spinal implants.
authors.affiliation: Department of Orthopaedic Surgery, Mie University Faculty of Medicine, Tsu, Mie, Japan. ykasai@clin.medic.mie-u.ac.jp
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kasai
authors.forename: Ryu
authors.initials: R
authors.lastname: Iida
authors.forename: Atsumasa
authors.initials: A
authors.lastname: Uchida
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000497:Alloys / Q000032:analysis; D000535:Aluminum / Q000097:blood; D002648:Child; D005260:Female; D006197:Hair / Q000378:metabolism*; D006801:Humans; D016268:Internal Fixators; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000097:blood* / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation*; D014025:Titanium / Q000097:blood*; D014639:Vanadium / Q000097:blood
chemical_list: D000497:Alloys; D014639:Vanadium; C031462:titanium alloy (TiAl6V4); D000535:Aluminum; D014025:Titanium