Abstract:

BACKGROUND: Because in vitro specimen of knee joint cannot simulate real movement of knee joint, and in vivo movement test cannot obtain movement information of bone structure, so accurate stability data of knee joint is not obtain which causes further study on early diagnosis and prevention measures of knee injury is unable.
OBJECTIVE: To study in vivo stability of the 6 degrees of freedom knee kinematics in patients with anterior cruciate ligament (ACL) injury under 134 N anterior loading by using three-dimensional (3D) reconstruction, two-dimensional (2D)/3D image registration and image processing technology.
METHODS: Totally 8 volunteers with unilateral ACL rupture and contralateral normal knee, CT (3D) images and 2D orthogonal images of the knee at 0°, 30°, 60°, and 90° under 134 N anterior loading were captured. These orthogonal images were used to recreate the in vivo knee positions at each of the targeted flexion angles by the method of 2D/3D registration. Comparison between the motion data of the mirror imaging uninjured knee and the injured knee was to get the 6 degrees of freedom kinematic difference of the intact and ACL deficient knee.
RESULTS AND CONCLUSION: After ACL injury, tibia antelocation were all increased. Tibia antelocation was minimal at 0°, maximal at 30°, gradually decreased at 60° and 90° and all the differences in each angle have statistical significance (P=0.000). The ACL injury knee has increased internal tibial rotation and internal tibial shift than intact knee (P=0.000). It is indicated that in vivo stability analysis of knee joint under static loading can achieve by the method of 2D/3D registration technique, and the ACL injured knee has increased tibia antelocation, internal tibial rotation and internal tibial shift.