J Oral Maxillofac Surg 60:623-628, 2002 Are High-Resolution Ultrasonographic Signs of Disc Displacement Valid? Ru ¨diger Emshoff, MD, DMD,* Siegfried Jank, MD, DMD,† Ansgar Rudisch, MD,‡ and Gerd Bodner, MD,§ Purpose: The study goal was to define the positive predictive value (PPV) for the diagnosis of disc displacement of the temporomandibular joint (TMJ) with the use of high-resolution ultrasonography (HR-US). Materials and Methods: TheHR-USreportsfor29patientsaged19to62yearswhohadaprospective clinical diagnosis of TMJ internal derangement were correlated with magnetic resonance results. Results: For the prospective HR-US interpretation, the PPV for disc displacement was 97% at the closed-mouth position and 88% at the maximum-mouth opening position. Conclusion: The PPV for the HR-US diagnosis of disc displacement is high. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:623-628, 2002 An temporomandibular joint (TMJ) internal derange- mentisoneofthemostcommontemporomandibular disorders. The term refers to clinical criteria that are used to classify TMJ disorders but generally is used to denote an abnormal positional relationship of the articular disc to the mandibular condyle and the ar- ticular eminence. These disorders have been associ- ated with characteristic clinical findings such as pain, joint sounds, and irregular or deviating jaw func- tion. 1-4 High-resolution ultrasonography (HR-US) imaging has been advocated for diagnosis 5-7 ; however, to the best knowledge of the authors, its reliability in the diagnosis of disc displacement has not been critically studied. Some HR-US signs attributed to disc displace- menthavebeendescribedasinsensitivebutrelatively specific. 6 However, specifity is independent of disor- der prevalence, and even a poor test may have high specifity for uncommon abnormalities (many true- negative results are associated with high specifity, even if most of the positive results of the test are false-positive). 8 To address this issue, this study was designed to enable determination of the positive pre- dictive value (PPV) of HR-US imaging for the detec- tion of disc displacements, with magnetic resonance imaging (MRI) as the standard of reference. The PPV, which represents how often an HR-US diagnosis of discdisplacementispredictiveofanMRIabnormality, reflects the true usefulness of HR-US imaging in this diagnosis. Materials and Methods From July 2000 through October 2000, 29 patients with symptoms of TMJ internal derangement were referred for MRI of the TMJ. There were 23 women and 6 men (age range, 19 to 62 years; mean age, 29 years). HR-US was performed immediately after MRI. The findings at US and MRI in these 29 patients (58 TMJs) were analyzed. All sonograms were obtained and interpreted pro- spectively by radiologist 1 (G.B.). The sonograms were performed with a real-time 12-MHz linear-array scanner on an HDI 5000 (Advanced Technology Lab- oratories,Bothell,WA).ThestaticHR-USinvestigation usedlongitudinaltotransversescansperformedatthe closed-mouth and maximum mouth opening posi- tions as described previously. 2 Each subject received an individual nonferromagnetic intermaxillary device *Associate Professor, Department of Oral and Maxillofacial Sur- gery, University of Innsbruck, Innsbruck, Austria. †Resident, Department of Oral and Maxillofacial Surgery, Uni- versity of Innsbruck, Innsbruck, Austria. ‡Consultant, Department of Radiology, University of Innsbruck, Innsbruck, Austria. §Associate Professor, Department of Radiology, University of Innsbruck, Innsbruck, Austria. Address correspondence and reprint requests to Dr Emshoff: Ho ¨henstraße5,A-6020Innsbruck,Austria;e-mail:Ruediger_Emshoff@ hotmail.com © 2002 American Association of Oral and Maxillofacial Surgeons 0278-2391/02/6006-0004$35.00/0 doi:10.1053/joms.2002.33105 623