Surgical site infections (SSIs) are a frequent complication of surgery and an important cause of postoperative morbidity. Infections that occur after spine fusion surgeries with permanent metal implants are particularly distressing for the patient. The impact of the size of the operating room (OR) as a likely risk factor for SSIs has not been studied much. A retrospective review was undertaken to examine the effect of the size of the OR on the risk of SSI in patients who underwent lumbar fusion surgery. 

This single institution study included 2523 patients who underwent 1- to 3-level open lumbar spine fusion between 2010 and 2016. Patients were excluded from the study if they had infection at the time of study entry, were younger than 18 years, had lumbar fusions that involved greater than 3 levels and underwent a staged anterior/posterior procedure if they were not done in the same OR. The ORs were grouped into two - large (Group A) and small (Group B) - based on the room volume. An OR was designated as small if it was below the mean OR size and large if it was greater than the mean OR size. There were eight small ORs and nine large ORs. Patients were also grouped into two based on OR size. 

Sixty-three (2.5%) patients developed SSIs; 46 (73%) in the larger OR group vs 17 (27%) in the smaller OR group. The rate of SSIs was 3.02% in larger ORs vs 1.81% in smaller ORs (P = 0.072). The size of the OR (group A vs group B) was also not found to be a significant predictor on bivariate or multivariate logistic regression analysis (p = .075 and p = .079); though, the trend in p values indicates some clinical association. Many other significant risk factors were also identified in this study such as BMI >30, smoking, more than one underlying comorbid conditions and more number of levels decompressed on bivariate and multivariate analysis. Topical vancomycin was found to significantly decrease rate of infection in both analyses.

Although the size of the OR (large OR vs small OR) was not found to be a significant predictor of SSIs, the study did observe a trend toward significance in the data, which is suggestive of a clinical association. The researchers suggest further analysis by prospective studies of the OR size on the infection rate and OR environmental risk factors.

Salmons HI, et al. Int J Spine Surg. 2019 Oct; 13(5): 423–428.