Personal, non-commercial use only. The Journal of Rheumatology. Copyright © 2004. All rights reserved. Jay, et al: Lubricating ability of synovial fluid 557 From the Section of Emergency Medicine, Department of Medicine, Brown University School of Medicine; Department of Engineering, Brown University, Providence; and Department of Biomedical Sciences, University of Rhode Island, Kingston, Rhode Island, USA. Supported by a National Institute on Aging Grant K08AG01008 (to GDJ), the McCutchen Foundation, and the University Emergency Medicine Foundation. G.D. Jay, MD, PhD; J. Zack, MD; K. Robinson, BS; F. Trespalacios BA; C-J. Cha, PhD, Section of Emergency Medicine, Department of Medicine, Brown University Medical School; K.A. Elsaid, MS; C.O. Chichester, PhD, Department of Biomedical Sciences, University of Rhode Island. Address reprint requests to Dr. G. Jay, Department of Emergency Medicine, Rhode Island Hospital, 593 Eddy Street, Providence, RI 02903. E-mail: gregory_jay_MD@brown.edu Submitted May 12, 2003; revision accepted August 5, 2003. Arthritis after joint injury involving a fracture extending into the synovial cavity is a well appreciated phenomenon 1,2 . Longitudinal studies support this observation, as well as a greater risk of knee osteoarthritis (OA) following fibula fracture and ligamentous and meniscal injuries 3 . Subclinical and repetitive trauma also lead to early OA 4 . It is generally unknown if acute but mild forms of trauma could also lead to degenerative joint disease. We wished to determine if emergency department (ED) patients diagnosed with knee joint synovitis show evidence of synovial fluid (SF) and articular cartilage deterioration. Emergency department management of weight bearing joint effusions is focused on determining the likelihood of fracture based on physical and radiographic findings, and the presence of infection or crystal induced synovitis 5 . Joint aspiration is also performed for patient comfort 6 . Suspicion of occult fracture in the traumatized knee joint that is radi- ographically negative prompts a diagnostic arthrocentesis 7,8 . In the absence of a history of trauma, aspirated SF is also examined for nucleated cells 9 , where counts exceeding 50,000/high powered field (hpf) may indicate a high proba- bility of infection 10 . SF is present to provide lubrication of apposed and pres- Lubricating Ability of Aspirated Synovial Fluid from Emergency Department Patients with Knee Joint Synovitis GREGORY D. JAY, KHALED A. ELSAID, JEFFREY ZACK, KRISTINE ROBINSON, FLOR TRESPALACIOS, CHUNG-JA CHA, and CLINTON O. CHICHESTER ABSTRACT. Objective. To determine if joint effusions encountered in the emergency department (ED) requiring arthrocentesis possess normal lubricating ability or evidence cartilage degeneration. Chondroprotection of articulating joint surfaces is provided by lubricin, a mucinous glycoprotein that is a product of megakaryocyte-stimulating factor gene (GenBank U70136) expression. Loss of synovial fluid’s (SF) lubricating ability has been implicated in the pathogenesis of degenerative joint disease. Methods. A retrospective ED observational study from May 1, 1999, to October 1, 2000, of adult and pediatric patients presenting with radiographically negative knee joint complaints and clinical evidence of joint effusion. Knee joints were aspirated by the emergency physician and the synovial fluid tested for lubricating ability and collagen type II degeneration. Lubricating ability was assayed in vitro in an arthrotripsometer oscillating latex apposed to polished glass under a load of 0.35 × 10 6 N/m 2 . Results were reported as the coefficient of friction (μ) relative to that of a 0.9% NaCl control; negative Δ μ value indicates lubrication. Comparisons of Δ μ were made to normal SF and aspirates from patients with osteoarthritis (OA) and rheumatoid arthritis. Collagen type II fragments were measured by a novel sandwich ELISA. Results. Synovial fluid aliquots (n = 57) lubricated poorly with Δ μ = –0.045 (95% confidence interval = –0.006, –0.083) compared to normal SF with Δ μ = –0.095 (95% CI = –0.088, –0.101). Only 20.6% of knee joint aspirates possessed normal lubricating ability. An association exists between nucleated cell count and Δ μ described by a logarithmic function. Collagen type II fragments were present in aspirates at a concentration of 0.636 μg/ml (95% CI 0.495–0.777 μg/ml), signifi- cantly higher than 0.173 μg/ml (95% CI 0.154–0.193 μg/ml) in the OA comparison group. Conclusion. Knee joints with synovitis, commonly encountered in the ED, are frequently nonlubri- cated bearings and display catabolism of collagen type II. This may play a role in acute cartilage destruction ultimately resulting in posttraumatic OA. (J Rheumatol 2004;31:557–64) Key Indexing Terms: JOINT LUBRICATION LUBRICIN SUPERFICIAL ZONE PROTEIN MEGAKARYOCYTE-STIMULATING FACTOR TRAUMATIC SYNOVITIS Personal, non-commercial use only. The Journal of Rheumatology Copyright © 2004. All rights reserved. www.jrheum.org Downloaded on October 1, 2021 from