A Simulation Study Of Marrow Fat Effect On Bone

Nowadays research on osteoporosis has become one of the most popular topics. Osteoporosis is a systemic skeletal disease characterized by low bone mass and micro architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture. Bone fracture is the key problem of osteoporosis. Approximately 90 million(7.01% of the populace) osteoporotic suffers have been found in C hina. In order to understand the mechanism of osteoporotic fracture, huge of studies have focused on the key factors of fracture. Especially in recent 10 years, bone strength is more and more emphasized rather than bone mineral density because the latter cannot explain the osteoporotic fracture solely. However, bone marrow was assumed to be negligible on the aspect of bone mechanical behavior, where bone mass and bone mineral density were most studied. As a result, if the bone marrow, especially the marrow fat, plays a role in the bone mechanical properties is unknown yet.Marrow fat content was found increased in osteoporotic bone. However, the relationship between such change of bone marrow and bone strength is not clear yet. This study was proposed to investigate the effect of marrow fat on the bone biomechanical performance by computer simulations. Based on quantitative C T technology, the microarchitecture of L3 lumber spine was achieved as a series of image sequences. The structural information of trabecular bone was kept as a set of data, and it can be reconstructed by three-dimensional reconstruction. Then finite element models of trabecular bone with and without marrow fat can be built to study the effect of fat marrow on bone mechanics. In each simulation, the two models were kept under the same condit ion. Simulations under different conditions were conducted on both models to mimic the various loading conditions in vivo. By establishing fluid structure interaction equations, the theory of trabecular bone deformation and marrow flow were clear, and the simulations on simplified sample help to understand the stress distribution.This paper applied finite element analysis in bone biomechanics to figure out the stress and strain distribution and the effect of fat marrow on bone mechanics. Results showed that under the same preset strain, the cancellous bone with marrow fat had higher maximum stress in trabeculae. This means that to achieve the same deformation, the model with fat marrow need s larger extra loading and the marrow fat has effect on bone biomechanics, which cannot be ignored. In other words, the increase of marrow fat in osteoporotic suffers is kind of a self- protection to help them resist trabecular bone deformation. Further, trabeculae with higher Elastic modulus tend to sustain a higher maximum compressive stress when considering the marrow fat. As a conclusion, the marrow fat has effect on bone biomechanics, which cannot be ignored. Such effect in osteoporosis should be further investigated in deep.