Q.Y.YEO1, A.T.C.LI1, C.A.NIRMAL1, J.C.C.LOW1, W.L.S.HO2
MOH Holdings Pte Ltd (MOHH)1, Tan Tock Seng Hospital2
Septic arthritis is an orthopaedic emergency with high morbidity and mortality. We set to determine (1) the risk factors associated with secondary surgery for septic arthritis of the native knee joint; (2) if serum inflammatory marker levels can predict the need for secondary surgery; and (3) if microbiology affect the need for secondary surgery.
This is a retrospective study reviewing all patients who underwent surgery for septic arthritis of the knee from Jan 2012 to Jun 2019 in a single institution. A total of 117 patients were recruited with 79 patients (67.5%) underwent one surgery and 38 patients (32.5%) underwent more than 1 surgery.
Patients with raised initial total white cell count of >20 x 109/L have an adjusted hazard ratio of 2.42 on the risk for secondary surgery, p= 0.03. A decline of CRP level of less than 20% within 24 hours from initial operation is a risk factor for secondary surgery and has an adjusted hazard ratio was 0.34, p= 0.004. Seventy-eight (84.8%) patients with positive bacterial growth in joint culture had gram positive infections and microbiology did not affect the risk of secondary surgery.
The risk factors for secondary surgery in patients with native knee joint septic arthritis are (1) raised initial total white cell count of >20 x 109/L, and (2) a less than 20% decline of CRP level within 24 hours from initial operation. These findings will guide clinicians to provide appropriate initial counselling and decision-making regarding secondary surgery for native knee joint septic arthritis.