Postoperative Wound Infections of the Spine

John M. Beiner, M.D., Jonathan Grauer, M.D., Brian K. Kwon, M.D., Alexander R. Vaccaro, M.D.


Neurosurg Focus. 2003;15(3) 

In This Article

Epidemiology and Risk Factors for Spinal Wound Infections

The rate of spinal wound infection in the literature ranges from 0.7 to 11.9%.[1,6,9,17,24] The type of surgery is perhaps the most significant variable affecting the rate of infection ( Table 1 ).[25]Simple lumbar discectomy carries a risk of infection of less than 1%[24] due to shorter operative times, less muscle trauma, and generally healthier patients than those requiring more extensive spinal procedures. There is some evidence that microdiscectomy may be associated with a higher risk of infection,[8] but this has not been substantiated by other published studies. When more extensive decompression is performed, without fusion, the risk of infection increases to 1.5 to 2%.[8,16,24] With the addition of fusion to the procedure, operative time is longer, blood loss is greater, and a separate operative site is usually required to harvest bone graft. The overall complication rate associated with a separate bone graft site itself is nearly 20%, some of which is related to infection. When instrumentation is used for lumbar fusions, the infection rate escalates to 3 to 6%.[8,12,24,25]

Other factors that predispose the patient to postoperative infection are extended prehospitilization, high blood loss (> 1000 ml), and prolonged operative time (> 3 hours).23 Although it is clear that in patients younger than 20 years of age infection rates are lower than those older than age 20 years, age alone does not seem to be an important predictor of postoperative wound infection.[2,12]

Malnourished patients are at extreme risk for postoperative infections of the spine. Protein and protein calorie malnutrition are associated with poor wound healing, increased postoperative infections, and immune suppression.[10] Assessment of the nutritional status of a patient should include measurement of albumin, prealbumin, and total lymphocyte counts. A serum albumin level lower than 3.5 g/dl and a total lymphocyte count lower than 1500 to 2000 cells/mm3 indicate malnourishment.[5,10] Because prealbumin levels more rapidly respond to the patient s nutrition, they may be used in the inpatient setting as a measure of successful ongoing nutritional replacement.

Staged spinal surgery is significantly associated with changes in a patient s nutritional status. Mandelbaum, et al.,[14] reported that 84% of patients undergoing staged anterior posterior spinal surgery became malnourished during their primary hospitalization; 27 of the 28 reported postoperative infections occurred in this malnourished group. In a different study, the authors compared same-day with staged anterior posterior spinal surgery.[4] Sixty-four percent of patients in the staged group and 77% of those in the same-day group experienced malnourishment after surgery. Hospital stay was longer and the infection rate higher in the staged-surgery group. The authors stressed that although many patients in both groups developed malnutrition, those requiring a second procedure suffered a greater number of complications. They recommended same-day anterior posterior surgery whenever possible.