Authors: Pamela Mehta, MS III, Stephen B. Schnall M.D., Charalampos Zalavras, M.D., Ph.D., Samer Alnajjar M.D.
Title: Septic Arthritis of the Upper Extremity: Shoulder, Elbow, and Wrist- An Epidemiological Survey
Purpose: To evaluate the presence of patient co-morbid conditions, the mechanism of development of the infection, the role of joint aspirate findings, and the microbiology of septic arthritis of the upper extremity.
Methods: A retrospective review of all patients admitted to our institution's musculoskeletal infection ward during the last ten years identified the patient cohort. Patients with a clinical diagnosis of an upper extremity septic joint were identified and their charts reviewed. Information recorded for each patient included demographic data, co-morbid conditions, history of trauma to the joint, joint aspirate findings, organism cultured, and treatment protocol.
Results: 52 patients (43 male and 9 female) with septic upper extremities were identified. 20 patients had a septic shoulder, 22 patients had a septic elbow and 10 patients had a septic wrist. The age of the patients ranged from 19 to 72 years with a mean age of 44.3 years. 12 patients (23%) had a history of trauma to the affected joint. 17 patients (33%) were found to have co-morbidities. A careful examination of the joint aspirate data revealed that 76% of patients had a WBC count greater than 50,000/mm3. However, 95% of our patients had greater than 80% PMNs and all patients had greater than 70% PMNs. 24 of the 52 patients (46%) had no growth at 48 hours due to empirical antibiotics that were started in the Emergency Department. However, of the organisms cultured, Staphylococcus aureus was most prevalent (16 of 52 patients, 31%). Only 2 patients (4%) grew a gram-negative organism.
Discussion: The current study identifies epidemiological and diagnostic features of septic upper extremity arthritis, such as patient co-morbid conditions, history of trauma to the joint, joint aspirate white blood cell count and differential, and organisms cultured. A clinical diagnosis of an upper extremity septic joint can be made from physical exam, but our study identifies more tangible patterns prevalent to this patient population and assists in future guidelines for diagnostic protocols.
Significance: The joint aspirate WBC differential is a very important diagnostic feature of septic upper extremity arthritis, and a high proportion of PMNs in the joint aspirate is a more sensitive finding than the absolute WBC count.