title: Progression of articular cartilage degeneration after application of muscle stretch.
abstract: The aim of study was to evaluate the progression of the ankle articular cartilage alterations after a post-immobilization muscle stretching. Twenty-nine Wistar rats were separated into five groups: C--control, S--stretched, SR--stretch recovery, IS--immobilized and stretched, and ISR--immobilized stretched recovery. The immobilization was maintained for 4 weeks and the left ankle was then stretched manually through a full dorsal flexion for 10 times for 60 s with a 30 s interval between each 60 s period, 7 days/week for 3 weeks. The recovery period was of 7 weeks. At the end of the experiment, the left ankles were removed, processed in paraffin, and stained in hematoxylin-eosin and safranin O. Two blinded observers evaluated the articular cartilage using the Mankin grading system (cellularity, chondrocyte cloning, and proteoglycan content) through light microscopy, and performed the morphometry (cellularity, total thickness, non-calcified thickness, and calcified thickness measures). Both the Mankin grading system and the morphometric analysis showed that the ISR group presented the most increased cellularity among the groups. The IS and SR groups showed the highest proteoglycan loss, and the ISR group showed the same content of proteoglycan observed in the C group. No significant differences were found in the chondrocyte cloning, the total cartilage thickness, the non-calcified cartilage thickness, and the calcified cartilage thickness among the groups. The results suggest that the cartilage can recover the proteoglycan loss caused by immobilization and stretching, probably because of the increased chondrocyte density. Therefore, the ankle articular cartilage responded as to repair the metabolic deficits.
authors.affiliation: Department of Physiotherapy, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
authors.forename: Carolina Náglio Kalil
authors.initials: CN
authors.lastname: Dias
authors.forename: Adriana Frias
authors.initials: AF
authors.lastname: Renner
authors.forename: Anderson Amaro
authors.initials: AA
authors.lastname: dos Santos
authors.forename: Fernando Augusto
authors.initials: FA
authors.lastname: Vasilceac
authors.forename: Stela Márcia
authors.initials: SM
authors.lastname: Mattiello
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000473:pathology*; D019902:Chondrocytes / Q000473:pathology; D002999:Clone Cells; D018450:Disease Progression; D007103:Immobilization; D052580:Muscle Stretching Exercises; D010619:Phenazines / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013194:Staining and Labeling; D013977:Tibia / Q000473:pathology
chemical_list: D010619:Phenazines; C009195:safranine T