The Effects of Meniscal Sizing on the Knee Using Finite Element Methods
The knee, one of the most complex joints in the body, is also one of the most commonly injured joints in humans. Most injuries that occur in the knee either cause meniscal damage or are the function of a previously damaged meniscus, a complex tissue that has been historically underappreciated. Many techniques for the replacement of a damaged meniscus have been surgically explored. The most successful approach thus far has been meniscus allograft, the transplantation of a meniscus from a cadaver to a patient. This procedure has been performed over the last 25 years with inconsistent results. Meniscal sizing appears to be a major source of this inconsistency. The purpose of this dissertation is to study the effects of meniscal sizing on stresses in the knee joint using finite element methods. All research was conducted on the porcine based on its similarity to the human knee. MRI and CT scans recreated the geometry of the knee. CT images were used to construct the shapes of bones and soft tissues were modeled from MRI. The geometric model included the femur, tibia, and both menisci. For simplicity, the material model used was a linear isotropic material even though this model does not adequately model the function of biological tissues. The geometric model was imported as a STL file and meshed with tetrahedral elements. The tibia was fully constrained on its distal surface, the menisci were constrained both at the horn attachments and their periphery, and the femur was constrained by a spring element mimicking the behavior of the entire bone of the femur, muscle, tendon, and ligament attachments. A force of 465 Newtons, half of the body weight of the porcine, was applied to the femur. The meniscus was scaled in three dimensions – medial-lateral, anterior-posterior, and proximal-distal – to examine the effects of differently sized menisci. Results demonstrate that all three dimensions are statistically significant, with the medial-lateral dimension being most significant. Even very small changes in meniscal size demonstrated dramatic changes in stress levels.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:meniscus knee allograft finite element geometric model porcine
Date of Publication:01/01/2005