title: Influence of Knee Immobilization on Chondrocyte Apoptosis and Histological Features of the Anterior Cruciate Ligament Insertion and Articular Cartilage in Rabbits.
abstract: This study examined the influence of immobilization on chondrocyte apoptosis and histological features of the anterior cruciate ligament (ACL) insertion and knee articular cartilage in rabbits. Forty-eight male Japanese white rabbits were assigned to an immobilization (n= 24) or sham (n= 24) group. Rabbits in the immobilization group underwent complete unilateral surgical knee immobilization and rabbits in the sham group underwent a sham surgery. The average thickness of the glycosaminoglycan (GAG) stained red area by safranin O staining, the chondrocyte apoptosis rate and the chondrocyte proliferation rate in the cartilage layer in the ACL insertion and the articular cartilage of the medial tibial condyle were measured at one, two, four and eight weeks in six animals from each group. In the ACL insertion, the chondrocyte apoptosis rate was higher in the immobilization group than in the sham group at two and eight weeks after surgery (p< 0.05). The chondrocyte proliferation rate gradually decreased from two weeks to eight weeks in the immobilization group. The GAG layer was thinner in the immobilization group than in the sham group at two, four and eight weeks after surgery (p< 0.05). In the articular cartilage, the chondrocyte apoptosis rate in the immobilization group was higher than in the sham group at four and eight weeks after surgery (p< 0.05). The GAG layer was significantly thinner in the immobilization group than that in the sham group at four and eight weeks after surgery (p< 0.05). Knee immobilization significantly increased chondrocyte apoptosis at two and eight weeks after surgery in the ACL insertion and at four and eight weeks after surgery in the articular cartilage of the medial tibial condyle, and decreased GAG layer thickness from two to eight weeks after surgery in the ACL insertion and from four to eight weeks after surgery in the articular cartilage.
authors.affiliation: Department of Orthopaedic Surgery, Ibaraki Prefectural University of Health Sciences, 4669-2 Ami, Inashiki-gun, Ibaraki 300-0394, Japan. mutsuzaki@ipu.ac.jp.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Mutsuzaki
authors.affiliation: Department of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Ibaraki 300-0393, Japan. hiromi.nakajima.vmd@vc.ibaraki.ac.jp.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakajima
authors.affiliation: Department of Rehabilitation Medicine, Ibaraki Prefectural University of Health Sciences, 4669-2 Ami, Inashiki-gun, Ibaraki 300-0394, Japan. wadano@ipu.ac.jp.
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Wadano
authors.affiliation: Department of Agriculture, Ibaraki University, 3-21-1 Chuo, Ami, Ibaraki 300-0393, Japan. 15a112g@vc.ibaraki.ac.jp.
authors.forename: Syogo
authors.initials: S
authors.lastname: Furuhata
authors.affiliation: Department of Orthopaedic Surgery, Tsukuba Gakuen Hospital, 2573-1 Kamiyokoba, Tsukuba, Ibaraki 305-0854, Japan. sakane-m@tsukuba-seikei.jp.
authors.forename: Masataka
authors.initials: M
authors.lastname: Sakane
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000473:pathology* / Q000601:surgery; D017209:Apoptosis; D002358:Cartilage, Articular / Q000473:pathology* / Q000601:surgery; D019902:Chondrocytes / Q000473:pathology*; D006025:Glycosaminoglycans / Q000378:metabolism; D007103:Immobilization; D020287:In Situ Nick-End Labeling; D007719:Knee Joint / Q000473:pathology*; D008297:Male; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011817:Rabbits; D013194:Staining and Labeling; D013977:Tibia / Q000473:pathology
chemical_list: D006025:Glycosaminoglycans; D018809:Proliferating Cell Nuclear Antigen
keywords: anterior cruciate ligament insertion; articular cartilage; chondrocyte apoptosis; glycosaminoglycan; immobilization