Metal levels in corrosion of spinal implants

Abstract

Corrosion affects spinal instrumentations and may cause local and systemic complications. Diagnosis of corrosion is difficult, and nowadays it is performed almost exclusively by the examination of retrieved instrumentations. We conducted this study to determine whether it is possible to detect corrosion by measuring metal levels on patients with posterior instrumented spinal fusion. Eleven asymptomatic patients, with radiological signs of corrosion of their stainless steel spinal instrumentations, were studied by performing determinations of nickel and chromium in serum and urine. Those levels were compared with the levels of 22 patients with the same kind of instrumentation but without evidence of corrosion and to a control group of 22 volunteers without any metallic implants. Statistical analysis of our results revealed that the patients with spinal implants without radiological signs of corrosion have increased levels of chromium in serum and urine (P < 0.001) compared to volunteers without implants. Corrosion significantly raised metal levels, including nickel and chromium in serum and urine when compared to patients with no radiological signs of corrosion and to volunteers without metallic implants (P < 0.001). Metal levels measured in serum have high sensibility and specificity (area under the ROC curve of 0.981). By combining the levels of nickel and chromium in serum we were able to identify all the cases of corrosion in our series of patients. The results of our study confirm that metal levels in serum and urine are useful in the diagnosis of corrosion of spinal implants and may be helpful in defining the role of corrosion in recently described clinical entities such as late operative site pain or late infection of spinal implants.

Prospective study on serum metal levels in patients with metal-on-metal lumbar disc arthroplasty

“…Kim et al [18] measured serum levels of nickel and chromium after posterior spinal arthrodesis using stainless steel implants and found that levels diminish rapidly with time but remained above normal levels after surgery suggesting that ion levels decrease as fusion occurred. A study by del Rio et al [19] described similarly elevated serum nickel and chromium levels in patients with instrumented spinal arthrodesis, noting the correlation between significantly higher metal ion levels and radiological signs of device corrosion. Rackham et al [21] determined that the number of metal connections/interfaces was positively correlated with serum chromium levels in a group of 30 patients undergoing posterior spinal arthrodesis.…”

“…Studies of metal ion levels in patients with spinal implants are less numerous. There have been only a few retrospective reports of metal ion levels in patients with stainless steel [18][19][20][21][22] and titanium [23,24] posterior spinal instrumentation. Less is known for metalon-metal total disc arthroplasty [25][26][27].…”

Metal ion release from fracture fixation devices: A potential marker of implant failure

“…In patients with spinal instrumentations, retrieved and characterized by signs of corrosion, even if without radiological symptoms, increased levels of chromium in serum and urine were present, compared with volunteers without implants 20…”

“…Higher Ni and Cr levels were found in subjects with corrosion of stainless steel posterior instrumented spinal fusion, in comparison with stable patients and controls 20…”

Urinary levels of nickel and chromium associated with dental restoration by nickel–chromium based alloys

“…For Ni-based restorative alloys, patients undergoing Ni–Cr replacement 1 year ago had a higher level of serum Ni than that of controls. 15 Other Ni-based implants have also demonstrated significantly increased Ni concentrations in body fluids after the implantation, such as hip prostheses, 29 cardiac device, 30 spinal instrumentation 31 and tungsten alloy. 32 …”