P28. Are serum ion levels elevated in pediatric patients with spinal implants versus controls

BACKGROUND CONTEXT Titanium (Ti) is thought to be among the most biocompatible metals. However, some authors have shown elevated serum Ti levels in children with spinal implants. Using state-of-the-art assay tools, we assessed serum ion levels in three groups of pediatric patients: 1) those with Ti growing spine devices, 2) those with Ti instrumentation for fusion, 3) control patients with extremity implants. PURPOSE We sought to determine the serum Ti, cobalt (Co) and chromium (Cr) levels in pediatric patients with growing spinal instrumentation compared to controls with implants placed for fracture treatment. We also examined human tissue biopsies adjacent to instrumentation for the presence of metal debris and macrophage activity. STUDY DESIGN/SETTING Prospective multicenter study. PATIENT SAMPLE N/A OUTCOME MEASURES N/A METHODS Pediatric patients undergoing growing rod or fusion surgery or other extremity implant removal (control group) had serum Ti, Co and Cr ion levels drawn at the time of surgery. Intraoperative waste tissue specimens were analyzed for the presence of metallic debris. Fifty patients had at least one set of labs (12 growing devices, 13 fusions, and 25 controls with limb implants). Growing spine devices included two magnetically controlled, five rib-based, and five traditional growing rods. Thirty-one patients had labs drawn on two occasions for validation purposes. RESULTS Serum Ti levels were significantly elevated in patients with growing spine devices at 3.1 ng/ml vs 1.1 ng/mL in those with extremity implants (p=0.007). Co level in the growing spine device group was 0.63 ng/mL, while in the control group it was 0.27 ng/mL (p=0.023). Cr levels in patients with growing spine devices was 1.18 ng/mL while in the control group it was 0.27 ng/mL (p=0.008) (Table 1). On matched pairs analysis, patients who had labs drawn before and after spine instrumentation had a statistically significant increase in Ti levels (0.91 ng/mL vs 3.3 ng/mL, respectively; p=0.02) (magnetic rods =1; Fusion =9). Tissue biopsies adjacent to Ti implants showed macrophage activity and presence of metal debris. CONCLUSIONS Serum Ti, Co and Cr levels were elevated in patients with indwelling metal implants, especially those with growing spine devices in place. Implantation of spinal fusion rods resulted in an increase in serum Ti levels. Although serum ion levels are elevated in children with metal implants, the clinical significance remains to be determined but is concerning in small patients with long periods of exposure to the devices. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Titanium (Ti) is thought to be among the most biocompatible metals. However, some authors have shown elevated serum Ti levels in children with spinal implants. Using state-of-the-art assay tools, we assessed serum ion levels in three groups of pediatric patients: 1) those with Ti growing spine devices, 2) those with Ti instrumentation for fusion, 3) control patients with extremity implants. We sought to determine the serum Ti, cobalt (Co) and chromium (Cr) levels in pediatric patients with growing spinal instrumentation compared to controls with implants placed for fracture treatment. We also examined human tissue biopsies adjacent to instrumentation for the presence of metal debris and macrophage activity. Prospective multicenter study. N/A N/A Pediatric patients undergoing growing rod or fusion surgery or other extremity implant removal (control group) had serum Ti, Co and Cr ion levels drawn at the time of surgery. Intraoperative waste tissue specimens were analyzed for the presence of metallic debris. Fifty patients had at least one set of labs (12 growing devices, 13 fusions, and 25 controls with limb implants). Growing spine devices included two magnetically controlled, five rib-based, and five traditional growing rods. Thirty-one patients had labs drawn on two occasions for validation purposes. Serum Ti levels were significantly elevated in patients with growing spine devices at 3.1 ng/ml vs 1.1 ng/mL in those with extremity implants (p=0.007). Co level in the growing spine device group was 0.63 ng/mL, while in the control group it was 0.27 ng/mL (p=0.023). Cr levels in patients with growing spine devices was 1.18 ng/mL while in the control group it was 0.27 ng/mL (p=0.008) (Table 1). On matched pairs analysis, patients who had labs drawn before and after spine instrumentation had a statistically significant increase in Ti levels (0.91 ng/mL vs 3.3 ng/mL, respectively; p=0.02) (magnetic rods =1; Fusion =9). Tissue biopsies adjacent to Ti implants showed macrophage activity and presence of metal debris. Serum Ti, Co and Cr levels were elevated in patients with indwelling metal implants, especially those with growing spine devices in place. Implantation of spinal fusion rods resulted in an increase in serum Ti levels. Although serum ion levels are elevated in children with metal implants, the clinical significance remains to be determined but is concerning in small patients with long periods of exposure to the devices.