Reduction of postoperative spinal infections based on an etiologic protocol

Acute postoperative spinal infections are serious complications. We saw a sudden increase in the infection rate in our unit during a 6-month period. This led us to construct an assessment protocol combining risk factors into a mnemonic we named the "Nine Ps Protocol" (patient-related factors, personnel, place, preoperative length of stay, procedure, prosthetics, prophylaxis, packed red blood cells, and pus cultures). We reviewed 102 consecutive patients having spine surgery in three sequential 6 month periods: Group A included 34 patients before the outbreak of infection and Group B included 26 patients during the outbreak of infection. We prospectively applied the protocol in 26 patients (Group C) after the outbreak. After the implementation of the protocol the infection rate dropped from 16.7% (Group B) to 3.6% (Group C). Increased risk factors for postoperative infection included advanced age, posterior instrumented fusion, high allogenic blood transfusion rates, and suboptimal sheet and dressing changing conditions. We propose the Nine Ps Protocol as a useful clinical tool for the etiologic assessment and prevention of spinal infections.