Septic Arthritis of the Wrist: Incidence, Risk Factors, and Predictors of Infection.

Septic arthritis of the wrist can result in permanent damage to the joint, making timely diagnosis crucial to initiate empiric antibiotics and surgical intervention. Although septic arthritis is routinely included in the differential diagnosis of atraumatic wrist pain, the incidence is unknown. Unlike large joints, there is no consensus on cell count values considered pathognomonic for wrist septic arthritis. The goal of this retrospective study was to determine the incidence of wrist septic arthritis and to identify the clinical, serum, and joint fluid values that predict infection. The records of patients who presented to a single urban hospital with a swollen, painful wrist without trauma during a 10-year period were reviewed. For patients who had a joint fluid analysis, the records were examined for history as well as demographic and laboratory data. Joint fluid analysis consisted of cell count, Gram stain, and cultures. Of 892 patients who met the inclusion criteria, 1.5% had wrist septic arthritis. Variables associated with septic arthritis included serum white blood cell count above 11,000/µL, core temperature above 100.4°F within 24 hours of aspiration, history of intravenous drug abuse, and smoking. No joint cell count analysis predicted septic arthritis, although patients with septic wrists had an elevated joint white blood cell count above 97,000/µL. Wrist septic arthritis is uncommon; however, objective factors can help identify patients at risk. Because joint cell count analysis cannot reliably predict a septic wrist, priority for joint aspirations with limited fluid should be given instead to Gram stain, culture, and crystal analysis. [Orthopedics. 2017; 40(3):e526-e531.].