title: Bone mass and quality in patients with juvenile idiopathic arthritis: longitudinal evaluation of bone-mass determinants by using dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, and quantitative ultrasonography.
abstract: BACKGROUND
  Our objective was to evaluate longitudinally the main bone-mass and quality predictors in young juvenile idiopathic arthritis (JIA) patients by using lumbar spine dual-energy X-ray absorptiometry (DXA) scan, radius peripheral quantitative computed tomography (pQCT), and phalangeal quantitative ultrasonography (QUS) at the same time.
  
  
  METHODS
  In total, 245 patients (172 females, 73 males; median age, 15.6 years: 148 oligoarticular, 55 polyarticular, 20 systemic, and 22 enthesitis-related-arthritis (ERA) onset) entered the study. Of these, 166 patients were evaluated longitudinally. Data were compared with two age- and sex-matched control groups.
  
  
  RESULTS
  In comparison with controls, JIA patients, but not with ERA, had a reduced spine bone-mineral apparent density (BMAD) standard deviation score (P < 0.001) and musculoskeletal deficits, with significantly lower levels of trabecular bone mineral density (TrabBMD) (P < 0.0001), muscle cross-sectional area (CSA) (P < 0.005), and density-weighted polar section modulus (SSIp) (P < 0.05). In contrast, JIA showed fat CSA significantly higher than controls (P < 0.0001). Finally, JIA patients had a significant reduced amplitude-dependent speed of sound (AD-SoS) (P < 0.001), and QUS z score (P < 0.005).
  
  
  CONCLUSIONS
  JIA patients have a low bone mass that, after a first increase due to the therapy, does not reach the normal condition over time. The pronounced bone deficits in JIA are greater than would be expected because of reduction in muscle cross-sectional area. Thus, bone alterations in JIA likely represent a mixed defect of bone accrual and lower muscle forces.
authors.forename: Stefano
authors.initials: S
authors.lastname: Stagi
authors.forename: Loredana
authors.initials: L
authors.lastname: Cavalli
authors.forename: Carla
authors.initials: C
authors.lastname: Signorini
authors.forename: Federico
authors.initials: F
authors.lastname: Bertini
authors.forename: Marco Matucci
authors.initials: MM
authors.lastname: Cerinic
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Brandi
authors.forename: Fernanda
authors.initials: F
authors.lastname: Falcini
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D001171:Arthritis, Juvenile / Q000000981:diagnostic imaging*; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D055815:Young Adult