title: Joint haemorrhage partly accelerated immobilization-induced synovial adhesions and capsular shortening in rats.
abstract: OBJECTIVE
  To elucidate the effects of intra-articular haemorrhage on the joint capsule of immobilized knees in rats.
  
  
  METHODS
  The unilateral knee joints were immobilized using a plastic plate and screws. Sham operated rats had only screws inserted. A single injection of fresh autologous blood was given postoperatively into the knee joints of the immobilized blood injection (Im-B) and the Sham blood injection (Sm-B) groups. Normal saline was administered for the immobilized-saline injection (Im-S) group. Sagittal sections were prepared from the medial midcondylar region of the knee and assessed with histological, histomorphometric, and immunohistochemical methods. The range of motion (ROM) was measured, and the mechanical property of the capsule was assessed by scanning acoustic microscope.
  
  
  RESULTS
  Absorption of the injected blood was delayed and made severe adhesions in the Im-B group. The length of the synovial membrane in the Im-B group was significantly shorter than that of the other groups. The ROM was significantly restricted in the Im-B group compared with the other groups. The elasticity of the posterior capsule in the Im-B group was significantly lower than that in the Sm-B group. Iron deposition was observed in the Im-B and Sm-B groups. Strong immunoreactivities of CD68, TGF-β1, and α-SMA were observed in the adhesion area of the Im-B group. Joint immobilization with blood injection caused severe capsular adhesion and limited range of motion. Immunostaining related to fibrosis increased with joint haemorrhage.
  
  
  CONCLUSIONS
  Intra-articular haemorrhage with joint immobilization might be an accelerated risk factor for joint contracture. It is likely that leaving a haematoma inside an immobilized joint should be avoided.
authors.affiliation: Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Onoda
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hagiwara
authors.forename: Akira
authors.initials: A
authors.lastname: Ando
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Eiichi
authors.initials: E
authors.lastname: Chimoto
authors.forename: Hideaki
authors.initials: H
authors.lastname: Suda
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yabe
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Saijo
authors.forename: Eiji
authors.initials: E
authors.lastname: Itoi
mesh_terms: D000818:Animals; D003286:Contracture / Q000473:pathology*; D004195:Disease Models, Animal; D006395:Hemarthrosis / Q000503:physiopathology*; D007103:Immobilization; D017746:Joint Capsule / Q000473:pathology* / Q000601:surgery; D007719:Knee Joint / Q000473:pathology* / Q000601:surgery; D008297:Male; D008855:Microscopy, Electron, Scanning; D016059:Range of Motion, Articular; D051381:Rats; D017207:Rats, Sprague-Dawley; D000074402:Synovectomy; D013583:Synovial Membrane / Q000473:pathology*; D000267:Tissue Adhesions / Q000473:pathology*