title: Mechanical properties of the anterior cruciate ligament chronically relaxed by elevation of the tibial insertion.
abstract: The effects of stress deprivation on the mechanical properties of the anterior cruciate ligament were studied in a canine model. Fifty-eight mature mongrel dogs were divided into two groups. In the relaxed group (n = 30), the tibial insertion of the anterior cruciate ligament in each right knee was surgically elevated proximally 3 mm from the tibia; the elevation was anatomically reduced in the sham group (n = 28). In order to obtain control data, the left knee in each dog was left untreated. A femur-anterior cruciate ligament-tibia complex was excised from each knee for biomechanical tests at 6 or 12 weeks after surgery. To simplify data analysis, the treat/nontreat ratio (the ratio of the data obtained from the treated knee to that from the nontreated knee) was used. The cross-sectional area of the ligament increased significantly in both groups; the area in the relaxed group (average treat/nontreat ratio = 1.37) was significantly larger than that in the sham group (1.16) at 6 weeks but not at 12 weeks. The treat/nontreat ratio of tensile strength in the relaxed group significantly decreased to 0.67 and 0.58 at 6 and 12 weeks, respectively; in the sham group, it significantly decreased to 0.79 at 6 weeks but subsequently increased to 0.87 at 12 weeks. Only at 12 weeks was a significant difference observed between the two groups. This study demonstrated that, in the anterior cruciate ligament, stress deprivation results in a rapid increase in the cross-sectional area, although this effect disappears by 12 weeks, and in a decrease in mechanical strength, although a relatively long period of more than 6 weeks is required for the deterioration.
authors.affiliation: Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Keira
authors.forename: K
authors.initials: K
authors.lastname: Yasuda
authors.forename: K
authors.initials: K
authors.lastname: Kaneda
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000502:physiology*; D001696:Biomechanical Phenomena; D003094:Collagen / Q000502:physiology; D004285:Dogs; D004867:Equipment Design; D013977:Tibia / Q000502:physiology*; D013997:Time Factors
chemical_list: D003094:Collagen