Dynamic stabilization: a nidus for infection?

Dynamic stabilization offers an adjunct to fusion with motion preservation. In comparison, standard instrumented fusion (if) consists of titanium screws and rods/plates, which do not allow for motion at the level of the fusion. The reported infection rate following a standard if ranges from 0.2% to 7%.

a retrospective chart review of 142 patients who underwent posterior lumbar stabilization procedures was conducted. Ten patients received dynamic stabilization and 132 patients had a standard if. Rates of infection, requiring hardware removal, were compared between the aforementioned groups.

Of the 132 patients undergoing posterior if, three developed a deep wound infection requiring removal of hardware (2.3%). Of the 10 patients undergoing dynamic stabilization, three developed a deep wound infection (30%) with 2 requiring removal of hardware (20%), secondary to persistent deep wound infection or osteomyelitis at the pedicle screw sites. There was a significantly increased risk of deep wound infection (p < 0.0001) with the use of dynamic stabilization compared to standard if.

Our series demonstrates that the infection rate in patients undergoing dynamic stabilization is higher than the infection rate for instrumented fusion without a significant difference in comorbidity scores. We postulate that the polycarbonate urethane spacer acts as a medium for bacteria, whereas the titanium screws and rods are smooth, solid, and inert, resulting in a lower risk of infection.