The Difference of Surgical Site Infection According to the Methods of Lumbar Fusion Surgery

Study Design: Retrospective analysis. Objective: To compare the rates and types of a surgical site infection according to the surgical options in spine surgeries. Summary of Background Data: Scant literatures exist on the difference of surgical site infection according to the surgical methods. We presumed that the incidence of infection after posterior lumbar interbody fusion (PLIF) was higher than posterior or posterolateral fusion (PF, PLF) due to several reasons. Methods: A retrospective analysis was made on the patients who received instrumented spinal fusion surgeries from 2000 to 2009. The differences of surgical site infection rates and characteristics were compared between the patients who received PF or PLF (group I) and PLIF (group II). In addition, the infection rate according to the graft options and number of cages was compared in group II. Results: A significant difference (P = 0.003) of infection rate between group I (0.3%, 3 cases out of 974) and group II (1.37%, 29 cases out of 2110) was observed. In group I, 67% of infections were wound infections and 33% were osteomyelitis. In group II, 23% were wound infections, 73% were osteomyelitis, and 4% were osteomyelitis combined with wound infection. Significant increase of infection rate was observed in the single cage group (P = 0.001) and mainly local bone grafted group (P = 0.030). Conclusions: The infection rate of PLIF was higher than that of PF or PLF. Considering the increased infection rate in local bone grafted group and 52% of the infection cases after interbody fusion was osteomyelitis around interbody space, contaminated local bones and interbody space were suspected as major routes of contamination. The higher infection rate in single cage group than that of double cage group was attributed to vulnerability of remained avascular disk materials to infection.