The Effects of Syphilis Infection on Total Knee Arthroplasty Outcomes: A Retrospective Cohort Study

<b>Objective:</b> This study investigated the impact of recent syphilis infection on postoperative outcomes following total knee arthroplasty (TKA). We hypothesized that patients with a documented history of syphilis infection would experience a higher rate of postoperative complications compared to those without such a history. <b>Methods:</b> We conducted a retrospective cohort analysis using a national insurance claims database. Our study population included 237,360 patients who underwent primary TKA between 2005 and 2024. Patients were classified into two groups based on the presence (+Syph) or absence (-Syph) of a syphilis diagnosis within one year prior to the TKA. We evaluated the rates of several postoperative complications at 30 days postsurgery, including infection, hematologic issues, and cardiac events. Statistical analyses between groups was performed using chi-squared tests and Fisher's exact tests. Routine demographic data such as age, sex, race, and comorbidities were also analyzed. <b>Results:</b> Among the 237,360 TKA patients, we identified 71 with a history of syphilis within one year of their surgery. The +Syph group exhibited significantly higher rates of periprosthetic infection (4.23% vs. 0.81%, <i>p</i> = 0.001), need for manipulation under anesthesia (MUA) at four months (7.04% vs. 2.82%, <i>p</i> = 0.032), deep venous thrombosis (4.23% vs. 1.27%, <i>p</i> = 0.026), periprosthetic fracture (2.82% vs. 0.23%, <i>p</i> < 0.001), and pneumonia (2.82% vs. 0.62%, <i>p</i> = 0.019) within 30 days postTKA. No significant differences were observed in 30-day mortality, deep or superficial surgical site infections, wound dehiscence, blood loss anemia, or transfusion requirements. Additionally, rates of acute renal failure, pulmonary embolism, and cardiac events did not differ significantly between groups. Demographically, patients in the syphilis cohort had a higher prevalence of smoking and diabetes preoperatively within one year of their surgical date. <b>Conclusions:</b> A documented syphilis diagnosis within one year of TKA significantly affects postoperative outcomes, increasing the rates of prosthetic joint infection, MUA, deep venous thrombosis, periprosthetic fracture, and pneumonia. These findings underscore the need for heightened vigilance in the pre- and postoperative management of patients with a history of syphilis infection undergoing TKA. Further research is warranted to explore the relationship between prior syphilis infection and TKA outcomes, as well as to develop strategies to mitigate this increased risk.