title: Coexistence of fibrotic and chondrogenic process in the capsule of idiopathic frozen shoulders.
abstract: OBJECTIVE
  To analyze changes in the capsule from idiopathic frozen shoulders and clarify their etiology.
  
  
  METHODS
  Samples (the rotator interval capsule, middle glenohumeral ligament (MGHL), and inferior glenohumeral ligament (IGHL)) were collected from 12 idiopathic frozen shoulders with severe stiffness and 18 shoulders with rotator cuff tears as a control. The number of cells was counted and the tissue elasticity of the samples was calculated by scanning acoustic microscopy (SAM). The amount of glycosaminoglycan content was assessed by alcian blue staining. Gene and protein expressions related to fibrosis, inflammation, and chondrogenesis were analyzed by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC). Furthermore, the total genes of the two groups were compared by DNA microarray analysis.
  
  
  RESULTS
  The number of cells was significantly higher and the capsular tissue was significantly stiffer in idiopathic frozen shoulders compared with shoulders with rotator cuff tears. Staining intensity of alcian blue was significantly stronger in idiopathic frozen shoulders. Gene expressions related to fibrosis, inflammation, and chondrogenesis were significantly higher in idiopathic frozen shoulders compared with shoulders with rotator cuff tears assessed by both qPCR and DNA microarray analysis.
  
  
  CONCLUSIONS
  In addition to fibrosis and inflammation, which used to be considered the main pathology of frozen shoulders, chondrogenesis is likely to have a critical role in pathogenesis of idiopathic frozen shoulders.
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. hagi@med.tohoku.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Hagiwara
authors.forename: A
authors.initials: A
authors.lastname: Ando
authors.forename: Y
authors.initials: Y
authors.lastname: Onoda
authors.forename: T
authors.initials: T
authors.lastname: Takemura
authors.forename: T
authors.initials: T
authors.lastname: Minowa
authors.forename: N
authors.initials: N
authors.lastname: Hanagata
authors.forename: M
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: E
authors.initials: E
authors.lastname: Chimoto
authors.forename: H
authors.initials: H
authors.lastname: Suda
authors.forename: N
authors.initials: N
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Sugaya
authors.forename: Y
authors.initials: Y
authors.lastname: Saijo
authors.forename: E
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000328:Adult; D002062:Bursitis / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D020219:Chondrogenesis / Q000502:physiology*; D004548:Elasticity; D005260:Female; D005355:Fibrosis; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D017746:Joint Capsule / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D017006:Rotator Cuff / Q000473:pathology; D000070636:Rotator Cuff Injuries; D012785:Shoulder Joint / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology