Please cite this article in press as: Lund B, et al. Reactive arthritis in relation to internal derangements of the temporomandibular joint: a case control study. Br J Oral Maxillofac Surg (2015), http://dx.doi.org/10.1016/j.bjoms.2015.04.008 ARTICLE IN PRESS YBJOM-4498; No. of Pages 6 British Journal of Oral and Maxillofacial Surgery xxx (2015) xxx–xxx Available online at www.sciencedirect.com Reactive arthritis in relation to internal derangements of the temporomandibular joint: a case control study Bodil Lund a,b,∗ , Anders Holmlund a,b , Bengt Wretlind c , Shah Jalal c , Annika Rosén a,d a Division of Oral and Maxillofacial Surgery, Department of Dental Medicine, Karolinska Institutet, Stockholm, Sweden b Department of Oral and Maxillofacial Surgery, Karolinska University Hospital, Stockholm, Sweden c Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Sweden d Division of Oral and Maxillofacial Surgery, Department of Clinical Dentistry, University of Bergen, Norway Accepted 9 April 2015 Abstract The aim of this study was to find out if reactive arthritis was involved in the aetiology of chronic closed lock of the temporomandibular joint (TMJ) by looking for bacterial antigens in the synovial membrane of the TMJ, and by studying the antibody serology and carriage of human leucocyte antigen (HLA) B27 in patients with chronic closed lock. Patients with reciprocal clicking and healthy subjects acted as controls. We studied a total of 43 consecutive patients, 15 with chronic closed lock, 13 with reciprocal clicking, and 15 healthy controls with no internal derangements of the TMJ. Venous blood samples were collected from all subjects for measurement of concentrations of HLA tissue antigen and serology against Chlamydia trachomatis, Yersinia enterocolitica, Salmonella spp., Campylobacter jejuni, and Mycoplasma pneumoniae. Samples of synovial tissue from patients with closed lock and reciprocal clicking were obtained during discectomy and divided into two pieces, the first of which was tested by strand displacement amplification for the presence of C trachomatis, and the second of which was analysed for the presence of species-specific bacterial DNA using 16s rRNA pan-polymerase chain reaction (PCR). There were no significant differences between the groups in the incidence of antibodies against M pneumoniae, Salmonella spp. or Y enterocolitica. No patient had antibodies towards C trachomatis or C jejuni. We found no bacterial DNA in the synovial fluid from any patient. The HLA B27 antigen was present in 2/15 subjects in both the closed lock and control groups, and none in the reciprocal clicking group. In conclusion, reactive arthritis does not seem to be the mechanism of internal derangement of the TMJ. © 2015 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons. Keywords: Temporomandibular joint; Internal derangement; Reactive arthritis; Chronic closed lock; Reciprocal clicking; Chlamydia trachomatis Introduction Internal derangements of the temporomandibular joint (TMJ) are common, with a prevalence of about 20% and a strik- ing, as yet unexplained, female predominance. They usually cause only minor symptoms that need either no treatment or conservative treatment for a limited time. In a few patients ∗ Corresponding author at: Department of Oral and Maxillofacial Surgery, Karolinska University Hospital, S-141 86 Stockholm, Sweden. Tel.: +46 0 8 58583950; fax: +46 0 8 58583522. E-mail address: bodil.lund@ki.se (B. Lund). the symptoms may be so serious that operation is indicated. From a clinical and tissue point of view, two variants of inter- nal derangement have been identified. 1,2 The first variant is called reciprocal clicking, which is a painful clicking or catching of the TMJ caused by a hypermobile disc with a callus in the posterior part of the disc. 3 This variant shows no sign of degenerative disease, and synovial inflammation (if present) is slight. 4 From a research perspective this group of patients may serve as an excellent control group when patients with degenerative or chronic inflammatory joint dis- ease are being studied. The second variant is chronic closed lock, which presents as impaired painful mobility of the TMJ. http://dx.doi.org/10.1016/j.bjoms.2015.04.008 0266-4356/© 2015 Published by Elsevier Ltd. on behalf of The British Association of Oral and Maxillofacial Surgeons.