Biomechanical assessment of disease outcome in surgical intervention for medial meniscal posterior root tears: efficacy and considerations

Abstract

Background The adverse consequences of medial meniscus posterior root tear have become more and more familiar to surgeons, and the treatment strategies have become increasingly abundant. In this paper, the finite element gait analysis method was used to explore the differences in the biomechanical characteristics of the knee joint under different conditions. Methods The CT computed tomography images of the knee joint were collected, and the CT two-dimensional tomographic images were converted into three-dimensional models through the procedures of gray value adjustment and regional growth. A structure with bone, cartilage, and meniscus was constructed (i) a finite element model of the intact knee joint. Next (ii) the slight tear model, (iii) the severe tear model, (iv) the entire tear model, (v) partial meniscectomy model, and (vi) meniscus repair model were constructed on the basis of the intact knee joint model. Different models were developed and analyzed under normal gait loading conditions. Results Under the gait load, the contact mechanics, kinematics and contact area of the medial and lateral interarticular compartment of the slight tear model and the severe tear model were not significantly different from those of the intact knee joint, while the severe tear model was significantly higher than the intact knee joint in the comparison of the local stress of the posterior root of the meniscus, and the average stress and peak stress increased by 267.1% and 202.9%, respectively. In addition, by comparing the performance of the partial meniscectomy model with the intact knee joint model, it can be concluded that partial meniscectomy did not show an improvement in cartilage contact behavior, and the average stress in the medial compartment still increased by 19.9%. The average contact area of femur and tibial cartilage decreased by 40.7% and 17.7% respectively. Meniscus repair has excellently achieved the task of restoring the biomechanics of the medial meniscus, and it is worth noting that it has also paid a high cost to achieve this benign outcome. The average stress of the posterior root of meniscus and tibial plateau increased by 127.1% and 271.6% respectively compared with the intact model. Conclusions The biomechanics of the knee joint is not sensitive to the level of tear of the posterior root. The improvement of partial meniscectomy in relieving intra-articular overload is limited, and the risk factors for accelerating the progression of osteoarthritis still exist. Meniscus repair is recommended for patients with medial meniscus posterior root tear to restore the biomechanical properties of the meniscus.