title: Early-stage hip involvement in patients with ankylosing spondylitis: A Chinese study based on magnetic resonance imaging.
abstract: OBJECTIVE
  To evaluate the clinical characteristics and identify potential factors of the early-stage hip involvement in patients with ankylosing spondylitis (AS) based on the magnetic resonance imaging (MRI).
  
  
  METHODS
  A cross-sectional retrospective study of 655 consecutive patients was performed. Patients with hip pain or limited hip function but lacking definitive evidence of hip involvement on radiography underwent hip MRI. Based on the results of the imaging tests, the patients were classified into three categories: (1) no hip involvement; (2) early-stage hip involvement according to MRI but not radiography; (3) advanced-stage hip involvement according to a Bath Ankylosing Spondylitis Radiology Index-hip score ≥2.
  
  
  RESULTS
  One hundred and sixty-eight patients had early-stage hip involvement and 103 patients had advanced-stage hip involvement. Multivariate logistic regression analysis indicated that younger age at onset, worse BASMI score, and more active inflammation in the sacroiliac joints were associated with the occurrence of early-stage hip involvement.
  
  
  CONCLUSIONS
  Negative plain radiography results cannot be used to rule out hip involvement. MRI was superior to radiography for the detection of early-stage hip involvement. Susceptible AS patients with symptoms or risk factors for hip involvement should undergo hip MRI to test for lesions in the early stage.
authors.affiliation: a Department of Rheumatology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China and.
authors.forename: Dongying
authors.initials: D
authors.lastname: Chen
authors.affiliation: b Department of Hematology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China.
authors.forename: Shiwen
authors.initials: S
authors.lastname: Yuan
authors.affiliation: a Department of Rheumatology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China and.
authors.forename: Zhongping
authors.initials: Z
authors.lastname: Zhan
authors.affiliation: a Department of Rheumatology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China and.
authors.forename: Youjun
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: a Department of Rheumatology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China and.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.affiliation: a Department of Rheumatology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China and.
authors.forename: Liuqin
authors.initials: L
authors.lastname: Liang
authors.affiliation: a Department of Rheumatology , The First Affiliated Hospital of Sun Yat-sen University , Guangzhou , China and.
authors.forename: Xiuyan
authors.initials: X
authors.lastname: Yang
mesh_terms: D000328:Adult; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging*; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging* / Q000473:pathology
keywords: Ankylosing spondylitis; Early stage; Hip involvement; Magnetic resonance imaging