title: Density, structure, and strength of the distal radius in patients with psoriatic arthritis: the role of inflammation and cardiovascular risk factors.
abstract: We investigated the densitometric and microstructural features of the distal radius in psoriatic arthritis (PsA) patients using high-resolution peripheral quantitative computed tomography. PsA patients have unique bone microstructural deficits, manifested as lower cortical bone density and higher cortical porosity, which are associated with a propensity to bone fragility.
  
  
  BACKGROUND
  The aim of this study was to investigate the densitometric, geometric, microstructural, and biomechanical features of the distal radius in psoriatic arthritis (PsA) patients.
  
  
  METHODS
  This study cohort consisted of 53 PsA patients (24 males and 29 females), with an average age of 53.1 years and 53 gender- and age-matched controls. Areal bone mineral density (aBMD) of the hip, lumbar spine, and ultradistal radius was measured by dual-energy X-ray absorptiometry. High-resolution peripheral quantitative computed tomography (HR-pQCT) was performed at the distal radius to obtain measures of volumetric BMD (vBMD), microstructure, and derived biomechanical indices.
  
  
  RESULTS
  There were no significant between-group differences in aBMD at the femoral neck, total hip, and ultradistal radius, while aBMD at the lumbar spine was significantly higher in patients. The only indices indicating compromised bone quality in PsA patients were related to cortical bone quality. Cortical vBMD were -3.8% significantly lower, while cortical pore volume, porosity index, and pore diameter were 108, 79.5, and 8.6%, respectively, significantly higher in patients. Cortical stress was marginally lower (-1.3%, p = 0.077) in patients with stress significantly more unevenly distributed (4.9%, p = 0.035). Endocortical perimeter and cortical pore volume were significantly higher in patients with vertebral fracture. Deficits in cortical bone quality were associated with indices of disease activity/severity and were more prominent in patients with type 2 diabetes mellitus or hypertension.
  
  
  CONCLUSIONS
  There is an intertwined relationship between chronic inflammation, cardiovascular risk factors, and bone loss in PsA. PsA patients seem to have unique bone microstructural deficits which are associated with a propensity to bone fragility.
authors.affiliation: Department of Medicine & Therapeutics, The Chinese University of Hong Kong, 9/F Clinical Sciences Building, Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, N.T., Hong Kong, SAR, China.
authors.forename: T Y
authors.initials: TY
authors.lastname: Zhu
authors.forename: J F
authors.initials: JF
authors.lastname: Griffith
authors.forename: L
authors.initials: L
authors.lastname: Qin
authors.forename: V W Y
authors.initials: VW
authors.lastname: Hung
authors.forename: T-N
authors.initials: TN
authors.lastname: Fong
authors.forename: S-K
authors.initials: SK
authors.lastname: Au
authors.forename: A W
authors.initials: AW
authors.lastname: Kwok
authors.forename: P-C
authors.initials: PC
authors.lastname: Leung
authors.forename: E K
authors.initials: EK
authors.lastname: Li
authors.forename: L-S
authors.initials: LS
authors.lastname: Tam
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000328:Adult; D015535:Arthritis, Psoriatic / Q000150:complications / Q000503:physiopathology*; D015519:Bone Density / Q000502:physiology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000503:physiopathology; D005260:Female; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000209:etiology* / Q000503:physiopathology; D058866:Osteoporotic Fractures / Q000209:etiology / Q000503:physiopathology; D011884:Radius / Q000503:physiopathology*; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000379:methods