Purpose

To evaluate the risk of post-operative infection after intra-articular steroid injection at the time of knee arthroscopy at a single institution high-volume sports medicine practice.

Methods

The electronic medical record at this institution was queried for all patients who underwent knee arthroscopy from November 2011 to April 2019. Patients who underwent more complex procedures, such as ligament reconstruction, meniscus repair, or open procedures were excluded. These patients’ medical records were then queried for current procedural terminology and international classification of disease codes indicating post-operative infection. Individual chart review was performed on this group of patients to determine if a true postoperative infection occurred within 6 months of the index arthroscopy. Patients were then categorized into “intra-operative steroid injection” versus “no steroid” based on surgeon preference.

Results

A total of 6,889 patients were identified, including 2,416 (35.1%) who were given intra-articular steroid at the time of knee arthroscopy. Post-operative infection occurred in 10 patients (0.15%) at a mean of 18 days (range: 9 to 42 days), 7 who received intra-operative steroid injection (0.29%) and 3 who did not (0.067%), p = 0.040. The relative risk of infection for those who received intra-operative steroid injection was 4.32 times higher than those who did not, with a number needed to harm of 448. There were no significant differences in age, body mass index, smoking status, or the prevalence of diabetes between those who got infected and those who did not.

Conclusions

Knee infection following arthroscopic surgery is rare. Intra-operative steroid injection during arthroscopic knee surgery is associated with a 4.3-fold increased risk of subsequent knee infection. While the overall risk remains low, the use of intra-operative steroids is expected to result in one additional knee infection for every 448.4 arthroscopic procedures performed.