Introduction: Instrumentation loosening and metal corrosion are predisposal factors under investigation for late Postoperative infections.
Purpose of the study: To investigate the contribution of the instrumentation material (stainless steel versus titanium implants) and the mechanical loosening in the development of late postoperative spinal infection.
Patients and methods: The first group of patients involves 50 idiopathic scoliotic patients who were treated with first generation posterior stainless steel spinal segmental multihook instrumentation. The minimum post operative follow up was 4 years. Five patients presented with late infections 1 to 5 years post operatively. Removal of instrumentation was the effective solution to this problem. Common intraoperative findings were some degree of instrumentation loosening and corrosion. The second group involves 40 idiopathic scoliotic patients who were treated with newer generation posterior titanium spinal segmental multihook-multiscrew instrumentation system. More extensive use of pedicle screws was performed to the second group resulting in a more stable mechanical construct. Follow up ranged from 2 to 5 years. None of those patients presented late postoperative infection or any evidence of instrumentation loosening or failure.
Conclusion: We believe that newer multihook-multiscrew titanium spinal instrumentation systems have smaller incidence of late postoperative infections because they provide a more stable construct (pedicle screws) with fewer tendencies for micro motion or failure, and they may give the advantage of greater bone adhesion on the implant resulting in the production of thinner biofilm, thus decreasing the chances of infection.