title: Osteopontin level in synovial fluid is associated with the severity of joint pain and cartilage degradation after anterior cruciate ligament rupture.
abstract: OBJECTIVE
  To explore the molecular function of Osteopontin (OPN) in the pathogenesis of human OA, we compared the expression levels of OPN in synovial fluid with clinical parameters such as arthroscopic observation of cartilage damage and joint pain after joint injury.
  
  
  METHODS
  Synovial fluid was obtained from patients who underwent anterior cruciate ligament (ACL) reconstruction surgery from 2009 through 2011 in our university hospital. The amounts of intact OPN (OPN Full) and it's N-terminal fragment (OPN N-half) in synovial fluid from each patient were quantified by ELISA and compared with clinical parameters such as severity of articular cartilage damage (TMDU cartilage score) and severity of joint pain (Visual Analogue Scale and Lysholm score).
  
  
  RESULTS
  Within a month after ACL rupture, both OPN Full and N-half levels in patient synovial fluid were positively correlated with the severity of joint pain. In contrast, patients with ACL injuries greater than one month ago felt less pain if they had higher amounts of OPN N-half in synovial fluid. OPN Full levels were positively correlated with articular cartilage damage in lateral tibial plateau.
  
  
  CONCLUSIONS
  Our data suggest that OPN Full and N-half have distinct functions in articular cartilage homeostasis and in human joint pain.
authors.affiliation: Department of Joint Surgery and Sports Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Yamaga
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Tsuji
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Miyatake
authors.forename: Jun
authors.initials: J
authors.lastname: Yamada
authors.forename: Kahaer
authors.initials: K
authors.lastname: Abula
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Ju
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sekiya
authors.forename: Takeshi
authors.initials: T
authors.lastname: Muneta
mesh_terms: D000293:Adolescent; D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D018771:Arthralgia / Q000209:etiology / Q000378:metabolism*; D001182:Arthroscopy; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000209:etiology / Q000378:metabolism*; D053495:Osteopontin / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013582:Synovial Fluid / Q000737:chemistry*
chemical_list: D053495:Osteopontin