Changes of articular cartilage after immobilization in a rat knee contracture model

Abstract

ABSTRACT:The objective was to determine the changes of articular cartilage of the knee joint during immobilization in a rat model. The knee joints of adult male rats were immobilized at 1508 of flexion using an internal fixator for 3 days, and 1, 2, 4, 8, and 16 weeks. The articular cartilage from the medial midcondylar region of the knee was obtained, divided into three areas (non-contact area, transitional area, contact area), and in each area, a degree of degeneration was evaluated by gross observation, histomorphometric grading, and measurements of thickness and number of chondrocytes. Elasticity of the articular cartilage was estimated by measuring the sound speed with use of scanning acoustic microscopy. Degeneration of the articular cartilage was mainly observed in the contact and transitional areas. Matrix staining intensity by safranin-O and number of chondrocytes were decreased in these two areas. The thickness of the articular cartilage in the noncontact and contact areas was unchanged, but it was increased in the transitional area. Decrease in sound speed was observed in the transitional area of both the femoral and tibial cartilage, indicating the softening of the articular cartilage. The changes of articular cartilage became obvious as early as 1 week after immobilization. These changes may be due to a lack of mechanical stress or a lack of joint fluid circulation during immobilization. Although we do not know the reversibility of these changes of articular cartilage, early mobilization is preferable to avoid these cartilage changes. ß

Resistance exercise recovers the structure of cartilage and synovial membrane of the ankle joint of rats after sciatic compression

“…Other authors found a reduction in cellular density 24,36,37 . According to Whiting and Zernicke 2 , prolonged physical exercise in animals can produce hypertrophy of the chondrocytes and an increase in their number.…”

“…Trudel, Jabi, Uhthoff 36 also found no change in thickness, although the articular cartilage did become irregular in the analyzed locations. Hagiwara, Ando, Chimoto, Saijo, Ohmori-Matsuda, Itoi 37 noted that the thickness of the articular cartilage of the knee increased in the transition region, which may have been related to the lack of use of the limb and decreased lubrication of the joint. Roos and Dahlberg 22 recorded an increase in the thickness of the knee cartilage after cardio and strengthening exercises.…”

“…Physical exercise has been seen as an important tool in maintaining the integrity of the cartilage, preventing degeneration and maintaining its biomechanical properties 49 . Compressive force, or shear force at the joint, can be produced by exercise, which leads to cartilage regeneration 37 and exerts a chondroprotective effect 50 . Hornberger and Farrar 18 subjected animals to resistance exercise by climbing stairs once every three days for eight weeks, with increasing load, and described an animal model that simulates the training parameters and physiological adaptations observed in humans.…”

Intra-articular Injection of Hyaluronan Diminishes Loss of Chondrocytes in a Rat Immobilized-Knee Model

“…The reported area of cartilage degeneration was mainly divided into three areas as follows; a non-contact area (Hall 1963;Kiviranta et al 1987;Säämänen et al 1987), a contact area (Evans et al 1960;Sood 1971), and both areas (Akeson et al 1980;Trudel et al 2005). We decided to choose three areas on each condyle to precisely evaluate the degenerative changes of the articular cartilage after immobilization, because the area between contact and non-contact area showed quite characteristic changes in our model (Hagiwara et al 2008). Our immobilization model showed severe changes in the articular cartilage; atrophic changes in the contact area, hypertrophic changes in the transitional area, and loss of safranin O staining intensity without any structural changes in the non-contact area.…”

“…By our gross observations, we chose 3 areas (noncontact area, transitional area, and contact area) from the articular surface of the femur and tibia as previously described (Hagiwara et al 2008) (Fig. 2).…”