Abstract
Introduction and Aims: Elevated chromium ion levels can be detected in serum following spinal arthrodesis with stainless steel. Comparing characteristics of spinal implants with chromium levels has not been done extensively before. The aim of our study was to compare an extensive range of implant characteristics with chromium levels.
Methods: Cross-sectional study of 30 patients (26 females and 4 males) who underwent posterior instrumented spinal arthrodesis using Isola implants including cables for adolescent scoliosis between 1998 and 2002. Patients who had postoperative complications and implants removed were excluded. Serum levels of chromium were analysed between October 2006 and June 2007. Post-operative radiography was used to measure rod length and count hooks, screws, cross-connectors and cables. Surface areas of each component of the implant was estimated and totalled. Metal-on-metal interfaces were calculated. Ethics approval was obtained from the WCH Research Ethics Committee.
Results: Both total surface area and total rod length were correlated with serum chromium levels (p = 0.04 and 0.05 respectively). This is the first study to identify a characteristic of spinal implants, other than the late signs of corrosion identified by radiographs, which has significance for serum chromium levels. None of our patients had signs of corrosion, pseudoarthrosis or rod breakage on radiological examination. Compared to raised serum chromium levels, the number of metal-onmetal interfaces approached significance (p = 0.09). Individual numbers of screws, hooks, cables or cross-connectors were not significantly associated with chromium levels.
Conclusions: Total rod length may contribute to elevated chromium levels in patients with stainless steel Isola spinal implants and warrants further investigation.
The abstracts were prepared by David AF Morgan. Correspondence should be addressed to him at davidafmorgan@aoa.org.au
Declaration of interest: a
