title: Diagnostic accuracy of ultrasound, conventional radiography and synovial fluid analysis in the diagnosis of calcium pyrophosphate dihydrate crystal deposition disease.
abstract: OBJECTIVE
  To assess the diagnostic performance of ultrasound (US), x-rays, and microscopic analysis of synovial fluid (SF) for calcium pyrophosphate dihydrate crystal deposition disease (CPPD) using histology as a reference standard.
  
  
  METHODS
  We enrolled consecutive patients with osteoarthritis waiting to undergo knee replacement surgery. Each patient underwent US of the knee, focusing on menisci and the hyaline cartilage, the day before surgery. During surgery, SF, menisci and condyles were retrieved and examined microscopically. For the meniscus and cartilage microscopic analysis, 8 samples were collected from each specimen and knee radiographs, performed up to 3 months before surgery, were also assessed. A dichotomous score was given for the presence/absence of CPP for each method. Microscopic findings of the specimens were considered the reference standard. All the procedures followed were in accordance with the ethical standards of the local responsible committee.
  
  
  RESULTS
  42 patients (14 males) were enrolled. All patients underwent US, 34 had eligible radiographs and 32 had SF analysis. 25 patients (59.5%) were positive for CPP at US, 15 (44.1%) at X-ray and 14 (43.7%) at SF. Sensitivity and specificity values were 96% and 87% for US, 75% and 93% for radiography and 77% and 100% for SF respectively. There were no statistically significant differences between the diagnostic performance across single tests.
  
  
  CONCLUSIONS
  US proved to be at least as accurate as SF analysis for the diagnosis of CPPD. US, which is feasible and harmless, could be considered the first exam of choice for CPPD diagnosis.
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy. gf.filippou@gmail.com.
authors.forename: Georgios
authors.initials: G
authors.lastname: Filippou
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Adinolfi
authors.affiliation: Academic Unit of Clinical Rheumatology and Research Laboratory, Dipartimento di Medicina Interna, University of Genova, Italy.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Cimmino
authors.affiliation: Epidemiology Unit, Italian Society for Rheumatology, Milano, Italy.
authors.forename: Carlo A
authors.initials: CA
authors.lastname: Scirè
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Orthopaedics Section, University of Siena, Italy.
authors.forename: Serafino
authors.initials: S
authors.lastname: Carta
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Sauro
authors.initials: S
authors.lastname: Lorenzini
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Santoro
authors.affiliation: Servizio di Radiologia, IRCCS Policlinico San Donato, San Donato Milanese; and Dipartimento di Scienze Biomediche per la Salute, Università degli Studi di Milano, Italy.
authors.forename: Luca M
authors.initials: LM
authors.lastname: Sconfienza
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Bertoldi
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Picerno
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Di Sabatino
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Orthopaedics Section, University of Siena, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ferrata
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Galeazzi
authors.affiliation: Department of Medicine, Surgery and Neurosciences, Rheumatology Section, University of Siena, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Frediani
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002131:Calcium Pyrophosphate / Q000032:analysis*; D002805:Chondrocalcinosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003460:Crystallization; D005260:Female; D006801:Humans; D008297:Male; D011859:Radiography; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000737:chemistry*; D014463:Ultrasonography
chemical_list: D002131:Calcium Pyrophosphate