Study of the effectiveness of the experimental model of immobilization contractures in rats

Abstract

Immobilization contractures are a common complication that can arise following prolonged immobilization of a joint or limb. They occur due to a combination of factors, including muscle atrophy, joint stiffness, and tissue adhesions. The aim of the study was to study the effectiveness of the experimental model of immobilization contractures in rats. The experimental study was conducted on 21 non-linear white male rats aged 6 months. We used 4-week plaster immobilization to evaluate the severity of changes in the knee joints of experimental rats. The immobilization and post-immobilization period in our study lasted 4 weeks each. Every week, the angles of extension and flexion, range of motion and severity of contracture were measured. During the period of immobilization, there was a progressive impairment of the function of the immobilized knee joints of all experimental animals. Thus, at the end of the 4th week of immobilization, the limits of flexion and extension on the immobilized limb gained high statistical significance in comparison with both the opposite intact limb and with 1st week of immobilization. In the post-immobilization period (from the 5th to the 8th week of the study), a progressive recovery of the studied indicators was observed. The indicators of extension and flexion of the limbs after immobilization were significantly differed from the initial values, but were also significantly better than the values at the end of the immobilization period. As for the range of motion, this indicator for both limbs was significantly higher than the values at 4th week of the study, but was also significantly lower than the initial values. Limitation of movements after immobilization was statistically significant both when compared with the opposite limb and when compared with baseline and 4th week of immobilization data. Experimental model of 4-weeks plaster immobilization of the knee joint allows to create a persistent pronounced limitation of movements and can be used for further study of various methods of prevention and treatment of immobilization contractures. Keywords: knee joint; immobilization contractures; experiment; rats.