title: Alterations of bone geometry, density, microarchitecture, and biomechanical properties in systemic lupus erythematosus on long-term glucocorticoid: a case-control study using HR-pQCT.
abstract: Compared to controls, HR-pQCT at distal radius of SLE patients on chronic glucocorticoid (SLE/GC) revealed reduced bone area, vBMD, deteriorated microarchitecture, and unevenly distributed stresses limited to cortical bone. Despite similar trabecular quality, whole bone strength decreased in patients. These alterations may partly explain high fracture rates in SLE/GC.
  
  
  BACKGROUND
  To assess bone geometric, densitometric, microarchitectural, and biomechanical properties in patients with systemic lupus erythematosus (SLE) on long-term glucocorticoid (GC) (SLE/GC) as compared with healthy controls.
  
  
  METHODS
  A total of 180 female SLE patients and 180 healthy controls were in this cross-sectional study to assess areal bone mineral density (aBMD) by dual-energy X-ray absorptiometry. High-resolution peripheral quantitative computed tomography (HR-pQCT) and microfinite element analysis (μFEA) was performed at distal radius.
  
  
  RESULTS
  In addition to significantly lower aBMD at femoral neck, total hip and lumbar spine, cortical area, average volumetric BMD (vBMD) and cortical vBMD also significantly reduced by 5.3, 5.7, to 1.9 % in SLE patients, respectively. Deteriorations of cortical microarchitecture were pronounced in patients, with 6.3 % reduction in cortical thickness and 13.6 % higher in cortical porosity. Local stresses were more unevenly distributed through cortical bone in patients. SLE/GC patients had decreased whole bone stiffness, estimated failure load, and apparent modulus. Parameters related to trabecular bone density and microarchitecture were comparable between patients and controls.
  
  
  CONCLUSIONS
  In SLE/GC patients, despite a reduction in bone area, vBMD and deteriorated microarchitecture and unevenly distributed stresses limited to the cortical compartment, whole bone strength decreased. HR-pQCT and μFEA were promising in elucidating the potential underlying pathophysiology of bone loss and propensity to fracture in SLE/GC and provide us additional information about alterations of bone quality which might better predict fracture risk beyond aBMD in SLE/GC.
authors.affiliation: Department of Medicine & Therapeutics, The Chinese University of Hong Kong, 9/F, Clinical Science Building, Prince of Wales Hospital, 30-32 Ngan Shing Street, Shatin, N.T., Hong Kong.
authors.forename: X L
authors.initials: XL
authors.lastname: Tang
authors.forename: L
authors.initials: L
authors.lastname: Qin
authors.forename: A W
authors.initials: AW
authors.lastname: Kwok
authors.forename: T Y
authors.initials: TY
authors.lastname: Zhu
authors.forename: E W
authors.initials: EW
authors.lastname: Kun
authors.forename: V W
authors.initials: VW
authors.lastname: Hung
authors.forename: J F
authors.initials: JF
authors.lastname: Griffith
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; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D016022:Case-Control Studies; D004334:Drug Administration Schedule; D005260:Female; D020342:Finite Element Analysis; D005938:Glucocorticoids / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications* / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000503:physiopathology; D008875:Middle Aged; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D011239:Prednisolone / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D011884:Radius / Q000000981:diagnostic imaging / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D005938:Glucocorticoids; D011239:Prednisolone