Paper of the Week: Risk Factors for Surgical Site Infection in Orthopaedic Oncology

Alex J. Anatone, MD, Nicholas C. Danford, MD, Eugene S. Jang, MS, MD, Anne Smartt, MD, Matthew Konigsberg, MD, Wakenda K. Tyler, MD

Journal of the American Academy of Orthopaedic Surgeons, Volume 28, Issue 20, 2020.
doi: 10.5435/JAAOS-D-19-00582

Summary by: Serge Tzeuton, BS

A common surgical complication is surgical site infection (SSI). This can be of particular concern to orthopedic oncologists, who often have to remove sizeable tumors. The risk factors for SSI specific to orthopedic oncology have yet to be extensively studied. This study aimed to find those specific risk factors in order to aid in the treatment decision-making process.

Anatone et al., at the Hospital of Special Surgery, performed a retrospective single-institution review of all procedures done by three orthopedic oncologists between January 2012 and January 2018. The patient population  included procedures where the preoperative diagnosis was that of a malignant or possibly malignant neoplasm of the bone or soft tissues in the extremities, spine, pelvis, or chest wall.

Several patient-related and procedure-related variables were recorded. For each variable, a univariate analysis was performed with respect to the likelihood of happening in the SSI group vs the non-SSI group. Subsequently, a multiple logistic regression was constructed using the statistically significant variables to determine predictors of SSI. Finally, subgroup analysis assessed whether preoperative chemotherapy or radiation were associated with increased risk of SSI.

Of the 2,124 procedures found via the search parameters, 624 patients undergoing 757 procedures met inclusion criteria. Seventy procedures developed SSI (9.2%). Univariate analysis identified malignancy (62.9% malignant versus 31.7%, p< 0.001), smoking history (30.0% versus 19.7%, p = 0.041), and ASA Score (1 [8.6%], 2 [48.6%], 3 [38.6%], 4 [4.3%] in SSI versus 1 [21.5%], 2 [52.5%], 3 [24.7%], 4 [1.2%] in non-SSI, p = 0.002) to be the patient-specific risk factors significantly associated with SSI. Similarly, longer surgery duration (190.23 minutes versus 107.24 minutes,  p< 0.001), higher estimated blood loss (1,237.26 mL versus 192.72 mL, p< 0.001), higher blood transfusion volume (576.43 mL versus 105.68 mL, p<0.001), preoperative chemotherapy (34.3% versus 12.8%, p< 0.001), and preoperative radiation (17.1% versus 5.5%, p< 0.001) were among the many procedure-specific risk factors associated with SSI. However, subgroup analysis showed that those who underwent preoperative chemotherapy or radiation were not more likely to develop SSI.

Surgeons cannot meaningful change most patient-specific risk factors identified by this study, but they can try to mitigate some procedure-related risk factors when aiming to prevent SSI. When deciding treatment options, orthopedic oncologists should take into consideration expected blood loss, blood transfusion requirements, and overall surgical duration when weighing the risk of SSI.  Of note, the study did not report how long patients were followed or differentiate between superficial and deep wound infections.