title: Cartilage matrix changes in contralateral mobile knees in a rabbit model of osteoarthritis induced by immobilization.
abstract: BACKGROUND
  Many researches have investigated the changes associated with immobilization-induced osteoarthritis (OA). However, there are only few studies focusing on the effect of unilateral knee immobilization on cartilage matrix changes in the contralateral mobile knee. The aim of the present study was to investigate the influence of immobilization on the cartilage matrix in the contralateral mobile knees in a rabbit model of OA induced by immobilization.
  
  
  METHODS
  Right knees (experimental knees) of eighteen mature female rabbits were immobilized at an extension of 180° with orthopedic casting tape for 2, 4, or 8 weeks. Left knees (contralateral knees) of the immobilized rabbits were not subjected to immobilization. The knees of six non-immobilized rabbits were designated as control knees. Following immobilization, cartilage specimens from the medial femoral condyle underwent macroscopic, histological, immunohistochemical, and biochemical evaluations.
  
  
  RESULTS
  Roughness of cartilage surface was detected in the experimental knees at 2 weeks, and cartilage degeneration was further developed. In the contralateral knee, cartilage showed degenerative changes after 4 weeks. Safranin-O staining and glycosaminoglycan (GAG) contents were reduced in the experimental knees following immobilization and in the contralateral intact knees after 4 and 8 weeks. Type II collagen staining was gradually reduced, type I collagen accumulation was obviously detected in the upper and middle layers of cartilage in experimental knees after 8 weeks, and the collagen orientation was gradually disorganized in both knees at 4 and 8 weeks. For both experimental and contralateral knees, collagen contents were significantly decreased at 8 weeks, and Mankin and Osteoarthritis Research Society International (OARSI) scores increased over time.
  
  
  CONCLUSIONS
  OA developed in the contralateral intact knee with the progress of OA in the immobilized knee in a rabbit model of immobilization-induced OA.
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. huanfeng3@126.com.|Department of Orthopedics, No. 454 Hospital of People's Liberation Army, Nanjing, Jiangsu, China. huanfeng3@126.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. weibo85@hotmail.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. weibo85@hotmail.com.|Digital Medicine Institute, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. weibo85@hotmail.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Wei
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 806790675@qq.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 806790675@qq.com.|Digital Medicine Institute, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 806790675@qq.com.
authors.forename: Shuai
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 723670019@qq.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 723670019@qq.com.
authors.forename: Fengyong
authors.initials: F
authors.lastname: Mao
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 605712964@qq.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 605712964@qq.com.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 1522885798@qq.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 987752695@qq.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. yaoqingqiang@gmail.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. yaoqingqiang@gmail.com.|Digital Medicine Institute, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. yaoqingqiang@gmail.com.
authors.forename: Qingqiang
authors.initials: Q
authors.lastname: Yao
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 153068833@qq.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 153068833@qq.com.|Digital Medicine Institute, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. 153068833@qq.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Orthopedics, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. limingwang99@hotmail.com.|Cartilage Regeneration Center, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. limingwang99@hotmail.com.|Digital Medicine Institute, Nanjing Medical University, Nanjing, Jiangsu, 210006, China. limingwang99@hotmail.com.
authors.forename: Liming
authors.initials: L
authors.lastname: Wang
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000473:pathology*; D024042:Collagen Type I / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D004195:Disease Models, Animal; D018450:Disease Progression; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D007103:Immobilization; D007150:Immunohistochemistry; D007719:Knee Joint / Q000473:pathology*; D020370:Osteoarthritis, Knee / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D011817:Rabbits
chemical_list: D024042:Collagen Type I; D024043:Collagen Type II; D006025:Glycosaminoglycans