RESUMEN
OBJECTIVE: The purpose of this study was to evaluate the influence of a change in the meniscus cross sectional shape on its position and on the biomechanics of a knee joint. METHODS: One main finite element model of a left knee joint was created on the basis of MRI images. The model consisted of bones, articular cartilages, menisci and ligaments. Eight variants of this model with an increased or decreased meniscus height were then prepared. Nonlinear static analyses with a fixed flexion/extension movement for a compressive load of 1000 N were performed. The additional analyses for those models with a constrained medio-lateral relative bone translation allowed for an evaluation of the influence of this translation on a meniscus external shift. RESULTS: It was observed that a decrease in the meniscus height caused a decrease in the contact area, together with a decrease in the contact force between the flattened meniscus and the cartilage. For the models with an increased meniscus height, a maximal value of force acting on the meniscus in a medio-lateral direction was obtained. The results have shown that the meniscus external shift was approximately proportional to the meniscus slope angle, but that relationship was modified by a medio-lateral relative bone translation. It was found that the translation of the femur relative to the tibia may be dependent on the geometry of the menisci. CONCLUSIONS: The results have suggested that a change in the meniscus geometry in the cross sectional plane can considerably affect not only the meniscal external shift, but also the medio-lateral translation of the knee joint as well as the congruency of the knee joint.
Asunto(s)
Articulación de la Rodilla/anatomía & histología , Articulación de la Rodilla/fisiología , Meniscos Tibiales/anatomía & histología , Meniscos Tibiales/fisiología , Modelos Anatómicos , Adulto , Fenómenos Biomecánicos , Cartílago Articular/anatomía & histología , Cartílago Articular/diagnóstico por imagen , Cartílago Articular/fisiología , Femenino , Análisis de Elementos Finitos , Humanos , Imagenología Tridimensional , Articulación de la Rodilla/diagnóstico por imagen , Imagen por Resonancia Magnética , Meniscos Tibiales/diagnóstico por imagen , Modelos Biológicos , Estrés MecánicoRESUMEN
OBJECTIVE: Evaluation of the biomechanical interaction between meniscus and cartilage in medial compartment knee osteoarthritis. METHODS: The finite element method was used to simulate knee joint contact mechanics. Three knee models were created on the basis of knee geometry from the Open Knee project. We reduced the thickness of medial cartilages in the intact knee model by approximately 50% to obtain a medial knee osteoarthritis (OA) model. Two variants of medial knee OA model with congruent and incongruent contact surfaces were analysed to investigate the influence of congruency. A nonlinear static analysis for one compressive load case was performed. The focus of the study was the influence of cartilage degeneration on meniscal extrusion and the values of the contact forces and contact areas. RESULTS: In the model with incongruent contact surfaces, we observed maximal compressive stress on the tibial plateau. In this model, the value of medial meniscus external shift was 95.3% greater, while the contact area between the tibial cartilage and medial meniscus was 50% lower than in the congruent contact surfaces model. After the non-uniform reduction of cartilage thickness, the medial meniscus carried only 48.4% of load in the medial compartment in comparison to 71.2% in the healthy knee model. CONCLUSIONS: We have shown that the change in articular cartilage geometry may significantly reduce the role of meniscus in load transmission and the contact area between the meniscus and cartilage. Additionally, medial knee OA may increase the risk of meniscal extrusion in the medial compartment of the knee joint.
Asunto(s)
Cartílago Articular/patología , Articulación de la Rodilla/patología , Menisco/patología , Osteoartritis de la Rodilla/patología , Fenómenos Biomecánicos , Cartílago Articular/anatomía & histología , Análisis de Elementos Finitos , Humanos , Articulación de la Rodilla/anatomía & histología , Menisco/anatomía & histología , Modelos Anatómicos , Estrés Mecánico , Tibia/anatomía & histología , Tibia/patología , Soporte de PesoRESUMEN
We present a three dimensional finite element analysis of stress distribution and menisci deformation in the human knee joint. The study is based on the Open Knee model with the geometry of the lateral meniscus which shows some degenerative disorders. The nonlinear analysis of the knee joint under compressive axial load is performed. We present results for intact knee, knee with complete radial posterior meniscus root tear and knee with total meniscectomy of medial or lateral meniscus. We investigate how the meniscus shape in the cross sectional plane influences knee-joint mechanics by comparing the results for flat (degenerated) lateral and normal medial meniscus. Specifically, the deformation of the menisci in the coronal plane and the corresponding stress values in cartilages are studied. By analysing contact resultant force acting on the menisci in axial plane we have shown that restricted extrusion of the torn lateral meniscus can be attributed to small slope of its cross section in the coronal plane. Additionally, the change of the contact area and the resultant force acting on the menisci as the function of compressive load are investigated.