title: Early acetabular cartilage degeneration in a rabbit model of developmental dysplasia of the hip.
abstract: BACKGROUND
  Mild developmental dysplasia of hip (DDH) causes high morbidity of osteoarthritis (OA) on adult. It is thought that change of collagen and proteoglycans in cartilage may be the direct reasons for osteoarthritis.
  
  
  OBJECTIVE
  To detect the changes of the expressions of type II collagen of acetabular cartilage in early DDH and to investigate the relevance between type II collagen and the degeneration mechanism of the acetabular cartilage.
  
  
  METHODS
  The rabbit model of DDH was successfully established by applying the method of knee extending and fixing with cylinder cast in which left lower extremity as experimental group and right one as control group, checking with X-ray after 5 weeks. The stains of H&E and toluidine blue were applied on the samples of acetabular cartilage to observe the morphological changes of chondrocytes and extracellular matrix (ECM). The immunohistochemical staining and Western-blot were employed to respectively qualify and quantitate the expression of type II collagen.
  
  
  RESULTS
  Pathohistology observing indicated the signs of retrogressive changes of acetabular cartilage in experimental group. Also, the positive stained cells in type II collagen in experimental group was higher based on immunohistochemiscal staining. The quantitative amounts of type II collagen by Western-blot in experimental group was higher significant difference existed between two groups (t = 2.18, P < 0.05).
  
  
  CONCLUSIONS
  The expression of type II collagen is correlated to a degeneration of acetabular cartilage and increase obviously in early DDH.
authors.affiliation: Department of Orthopedics, Nanjing Medical University Affiliated Suzhou Hospital (Suzhou Municipal Hospital) Suzhou 215002, China.
authors.forename: Xiangxin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, Nanjing Medical University Affiliated Suzhou Hospital (Suzhou Municipal Hospital) Suzhou 215002, China.
authors.forename: Qingxia
authors.initials: Q
authors.lastname: Meng
authors.affiliation: Department of Pediatric Orthopedics, Children's Hospital of Fudan University Shanghai 201102, China.
authors.forename: Ruixue
authors.initials: R
authors.lastname: Ma
authors.affiliation: Department of Orthopedics, Nanjing Medical University Affiliated Suzhou Hospital (Suzhou Municipal Hospital) Suzhou 215002, China.
authors.forename: Guangxiang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, Nanjing Medical University Affiliated Suzhou Hospital (Suzhou Municipal Hospital) Suzhou 215002, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Department of Orthopedics, Nanjing Medical University Affiliated Suzhou Hospital (Suzhou Municipal Hospital) Suzhou 215002, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Shen
keywords: Hip; bone disease; collagen; developmental; osteoarthritis