Effect of partial posterior root tear of medial meniscus on biomechanics of the knee joint during gait cycle
Xu Zhi1, Li Yuwan2, Jin Ying3, Liu Yi3
1Department of Orthopedics, Zhangjiagang Fifth People’s Hospital, Zhangjiagang 215600, Jiangsu Province, China; 2Department of Sports Medicine, Peking University Third Hospital, Institute of Sports Medicine of Peking University, Beijing Key Laboratory of Sports Injuries, Beijing 100191, China; 3Department of Orthopedics, Affiliated Hospital of Zunyi Medical University, Zunyi 563000, Guizhou Province, China
Abstract: BACKGROUND: At present, most of biomechanical studies on medial meniscus posterior root tearing to accelerate knee joint degeneration are limited to testing the complete tear model of the posterior root of the medial meniscus on the basis of static simulation design. However, the biomechanical behavior of medial meniscus posterior root tear in the full gait cycle is not clear.
OBJECTIVE: To compare the biomechanical differences between the normal knee joint model and the medial meniscus posterior root partial tear model in the complete gait cycle using dynamic finite element analysis method.
METHODS: Based on the CT scan data of the right knee joint of healthy adults, the finite element model of healthy knee joint including bone, meniscus and articular cartilage was established, and the posterior root tear model of medial meniscus of knee joint was further established on the basis of healthy model. The standard gait load of ISO was applied to the two models for simulation test. The differences of stress, displacement and contact area of the corresponding parts of the two models were compared.
RESULTS AND CONCLUSION: (1) Under the complete gait cycle, the stress distribution of the posterior root of the medial meniscus in the healthy model was uniform, while the pathological model showed stress concentration in the injured area. The maximum stress of the former appeared at the inner edge of the lateral meniscus at 30% time, with a value of 29.68 MPa. The latter maximum stress appeared at the inner edge of the lateral meniscus at 50% time, with a value of 30.34 MPa. (2) During the complete gait cycle, the stress distribution of tibial cartilage in healthy and pathological models was roughly the same. The maximum stress of the two models appeared at 50% and 20% around the gait, respectively, and the values were 5.11 MPa and 6.85 MPa, respectively. (3) The difference between the medial intercompartment group and the lateral intercompartment group was greater than that in the lateral intercompartment group. The average stress of the medial tibial plateau of the pathological model was 9.3% higher than that of the normal model, and the maximum value of 5.73 MPa appeared in the middle of the support phase. The peak contact area of femur and tibia appeared at 40% time, and the average contact area of femoral cartilage in each phase of the pathological model decreased by 14.6% compared with the normal model. (4) The results show that alterations in the biomechanical properties of the knee joint after a partial tear of the medial meniscus posterior root increase the risk of osteoarthritis.
Key words: medial meniscus posterior root tears, finite element analysis, biomechanics, gait cycle, knee joint