Septic arthritis (SA) of the native knee joint is rare but difficult to manage. Open or arthroscopic debridement is currently the most widely used approach. The problem is that there is a 71% and 50% chance of requiring revision surgery, respectively. Patients with recurrent sepsis may require arthrodesis or amputation, which would result in severe functional loss. Therefore, there is an urgent need to find more effective surgical procedures. Investigators developed a two-stage exchange with low-dose antibiotics for the treatment of SA and evaluated its efficacy.

Septic arthritis (SA) of the native knee joint is a rare but highly disabling disease. Epidemiologic studies have documented an incidence of 0.9 per 100,000. The treatment is challenging and the ideal treatment strategy is not well established. Over the past decades, open or arthroscopic debridement with systemic antibiotic therapy is the most widely used approach. However, a recent study has shown that these two methods have a failure rate as high as 50%-71%. Patients with recurrent sepsis may require arthrodesis or amputation, which would result in severe functional loss. Therefore, there is an urgent need to find more effective surgical procedures.

A few reports proposed two-stage exchange to address SA and showed satisfying clinical outcomes. Orthopedic surgeons removed the infected soft and bone tissue during the first operation and then implant antibiotic-loaded bone cement spacer. Once the infection had been addressed, a new prosthesis was inserted in a second operation. This approach could greatly boost the success rate to over 95%. However, the issue is that high-dose antibiotics bone cement may cause life-threatening complications such as acute kidney injury and drug-induced immune hemolytic anemia. Therefore, investigators developed a two-stage exchange with low-dose antibiotics for the treatment of SA.

Investigators summarized and analyzed the treatment processes and performed laboratory, imaging, and functional evaluations after treatment. The purpose was to introduce a new treatment regimen for SA and evaluate the technical points of the regimen, and prognosis over medium-term follow-ups.

Inclusion Criteria:

• Diagnosed with SA based on one or more of the following: clinical presentations (fever, joint pain, restricted mobility, swelling and redness, and/or a discharging sinus communicating with the joint); elevated inflammation markers; evidence of infection on images; purulence in the joint, and positive frozen section or cultures
• Without infections at other sites
• Without venous thrombosis of the lower limbs
• American society of Anesthesiologists (ASA) physical status classification was either 1 or 2
• With complete data for the main indicators (routine blood test results, C-reactive protein level, erythrocyte sedimentation rate, X-ray and/or MRI scans of the surgical site, and the Knee Society Function scores).

Exclusion Criteria:

• Patients (<60 yrs) without progression to advanced osteoarthritis
• In poor general condition who could not tolerate surgery