The effects of immobilization duration on joint contracture formation after anterior cruciate ligament reconstruction in rats

• Published in: Clinical biomechanics (Bristol) 2023-03, Vol.103, p.105926-105926, Article 105926
• Main Authors: Kaneguchi, Akinori, Ozawa, Junya, Yamaoka, Kaoru
• Format: Article
• Language: English
• Subjects: ACL reconstruction; Animals; Anterior Cruciate Ligament Injuries - surgery; Anterior Cruciate Ligament Reconstruction; Arthrofibrosis; Contracture; Immobilization; Inflammation; Joint contracture; Joint immobilization; Knee Joint - surgery; Range of Motion, Articular; Rats
• ISSN: 0268-0033; 1879-1271
• DOI: 10.1016/j.clinbiomech.2023.105926

Both myogenic and arthrogenic factors contribute to contracture formation after anterior cruciate ligament reconstruction surgery. However, effects of immobilization duration on myogenic and arthrogenic contractures after surgery are unknown. We examined the effects of immobilization duration on contracture formation. Rats were divided into groups according to treatment received: untreated control, knee immobilization, anterior cruciate ligament reconstruction, and anterior cruciate ligament reconstruction plus immobilization. Extension range of motion before and after myotomy as well as histomorphological knee changes were assessed two or four weeks after experiment commencement. Range of motion before myotomy mainly represents contractures due to myogenic factors. Range of motion after myotomy represents arthrogenic factors. Range of motion before and after myotomy was decreased in the immobilization, reconstruction, and reconstruction plus immobilization groups at both timepoints. In the reconstruction plus immobilization group, range of motion before and after myotomy was significantly smaller than in the immobilization and reconstruction groups. Shortening and thickening of the posterior joint capsule was induced in the immobilization and reconstruction groups. In the reconstruction plus immobilization group, capsule shortening was facilitated via adhesion formation, as compared to the immobilization and reconstruction groups. Our results indicate that immobilization after anterior cruciate ligament reconstruction surgery facilitates contracture formation via exacerbation of both myogenic and arthrogenic contractures within two weeks. Capsule shortening would be one of the main mechanisms for severe arthrogenic contracture observed in the reconstruction plus immobilization group. Periods of joint immobilization after surgery should be minimized to reduce contracture. •Joint contracture develops after anterior cruciate ligament reconstruction surgery.•Effects of immobilization duration on contractures after surgery are unknown•Two weeks of immobilization facilitated formation of joint contracture•Four weeks of immobilization further developed joint contractures•Periods of immobilization after surgery should be minimized to reduce contracture