Extension of knee immobilization delays recovery of histological damages in the anterior cruciate ligament insertion and articular cartilage in rabbits

Abstract

[Purpose] To investigate the influence of knee immobilization period on recovery of histological damages in the anterior cruciate ligament (ACL) insertion and articular cartilage in rabbits. This knowledge is important for determining the appropriate rehabilitation approach for patients with ligament injuries, fracture, disuse atrophy, and degenerative joint disease. [Materials and Methods] Forty-eight male Japanese white rabbits were divided equally into the remobilization and control groups. The remobilization group had the right knee surgically immobilized, and was divided equally into four subgroups according to the duration of immobilization (1, 2, 4 and 8 weeks). After the immobilization was removed, the rabbits moved freely for 8 weeks. The control group underwent sham operation and followed the same time course as the remobilization group. The chondrocyte apoptosis rate and chondrocyte proliferation rate in the ACL insertion and articular cartilage were analyzed after remobilization. [Results] In the ACL insertion, the remobilization group had a higher chondrocyte apoptosis rate than the control group after 8 weeks of immobilization, and a lower chondrocyte proliferation rate than the control group after 4 and 8 weeks of immobilization. In the articular cartilage, the remobilization group had a lower chondrocyte proliferation rate than the control group after 8 weeks of immobilization. After 8 weeks of remobilization, the ACL insertion and articular cartilage are not completely recovered after 4 and 8 weeks of immobilization, respectively. [Conclusion] Our results suggest that 8 weeks of remobilization will result in recovery of the ACL insertion after 2 weeks of knee immobilization, and recovery of the articular cartilage after 4 weeks of knee immobilization. If 8 weeks of immobilization occurs, a remobilization duration of more than 8 weeks may be necessary.

Cartilage articulation exacerbates chondrocyte damage and death after impact injury

“…Complete immobilization of knee joints has been noted to be beneficial for up to 2 weeks post-surgery by decreasing rate of apoptosis and increasing rate of proliferation. 25 However, immobilization of longer than 2 weeks or shorter than 1 week has been noted to cause further damage within the joint by increasing rate of apoptosis, decreasing rate of proliferation, and decreasing glycosaminoglycan content. 26 Since the timeline of cartilage damage to PTOA is not fully understood, it is unclear if movement of an injured joint may further damage chondrocytes.…”

Mechanical Unloading of Engineered Human Meniscus Models Under Simulated Microgravity: A Transcriptomic Study

“…A plethora of in vitro and in vivo studies show joint cartilage atrophy after long-term mechanical unloading (i.e., joint immobilization) [15][16][17][18][19][20][21][22][23][24] . For example, in a case study involving ten healthy young individuals (4 males and 6 females), with no history of KOA requiring 6 to 8 weeks of non-weight bearing for injuries affecting the distal lower extremity, the axial mechanical unloading of the joint resulted in increased magnetic resonance imaging (MRI) parameters, T1rho and T2 relaxation times, of the knee articular cartilage that resembled signs of KOA.…”

Structure of the Knee Articular Cartilage After the Femur and Tibia Extra-Articular Injury

“…The changes within cells and cartilage matrix had the degenerative-dystrophic character. Though, Mutsuzaki et al showed that knee immobilization after anterior cruciate ligament insertion leads to chondrocyte apoptosis activation as well as to thinning of cartilage layers [21]. This is the first report about the effect of femur and tibia extra-articular injury on the structure of the knee articular cartilage.…”