Histopathological Changes of Joint Capsule after Joint Immobility Compared with Aging in Rats

Abstract

Abstract. [Purpose] We examined the histopathological changes in the joint capsule that occurred due to long-term immobilization of the joint, and compared them with those seen in aged rats.[Subjects] A total of 26 male Wistar rats were used in this study.[Methods] The right knee joints of the experimental group rats were immobilized for periods of 2, 4, 8, 16, or 32 weeks, and three 13-week-old "adult" rats and three 70-week-old "aged" rats were used as control groups. At the end of each immobilization period, the right knee joints of the rats were used as samples for histological examination.[Results] We observed histopathological changes in the joint capsules occurring due to joint immobilization. Increase in the thickness of the joint capsule had occurred by 4 weeks of immobilization and developed with prolongation of the immobilization period. An increase in the thickness was also observed in the joint capsule of aged rats. Further, the areas of elastic fibers in aged rats and those immobilized for 32 weeks were decreased compared to adult rats.[Conclusion] The joint capsules after immobility and aging showed similar changes, suggesting that some kind of identical mechanism causes the two conditions.

Histopathological Changes in Knee Joint Components after Spinal Cord Injury in Rats

“…This finding resembles the change observed in joint immobility after CI reported by Watanabe et al 1) . We suggest that decrease in synovial perfusion and abnormal muscle contraction arising from loss of load on the cartilage may be possible causes of this change.…”

“…In a previous study of the histopathological changes in fatty synovial membrane after 2-week knee joint immobilization in rats, adipose cells were atrophied 1) . In the present study, atrophy and the fibrosis of the adipose cells were observed in the fat pad around the synovial membrane, in particular under the patellar ligament region in the SCI-2w group.…”

“…Joint immobility may be caused by cast immobilization (CI), external fixation, or after neurological paralysis. Variable and somewhat controversial morphological alterations in the knee joint components resulting from immobilization have been described, and the changes include, increased thickness and decreased area of elastic fibers of the joint capsule 1) , increased surface irregularity [2][3][4] , increased or decreased or unchanged thickness of cartilage [5][6][7][8] , decreased synovial intima length 9) , augmentation of levels of type I c o l l a g e n i n t h e s y n o v i a l i n t i m a 1 0 ) , s y n o v i o c y t e proliferation 11,12) and decreased cross-sectional areas of myocytes 13) .…”

“…Several studies have described the histopathological changes in joint components after CI 1,[9][10][11][12]14) . Previous reports on the effect of immobilization of the hindlimb after spinal cord injury (SCI) have mainly focused on its n e u r o l o g i c a l c o n s e q u e n c e s a n d w e r e b a s e d o n morphometric studies such as evaluation of the range of motion 15) or muscle fiber diameter 16) of the hindlimb.…”

Histopathological Changes in Surrounding Tissue of the Sciatic Nerve after Spinal Cord Injury in Rats

“…Several studies have described pathological changes in muscle, connective tissue, and joint components after cast or splint immobilization [7][8][9][10][11][12] . Previous reports on the effect of immobilization of the hindlimb after SCI mainly focused on the neurological consequences and were based on morphometric studies, such as evaluation of the range of motion 13) or muscle fiber diameter 14) of the hindlimb.…”