Simulations Of The Osteoarthritis On The Edge Of Lumbar Vertebra

The incidence of osteoarthritis(OA) is so high that the disease attracts a great deal of researcher. At present, most of the researchs on the pathogeny and the pathogenesis of osteoarthritis are from the point of physiology, biochemistry and biomechanics. but it is not reported at home and overseas studying osteoarthritis through using bone functional adaptability theory.Lumbar vertebrae is the foremost bearing force articulation, and it is the position which occurs osteoarthritis most easily. Many factors cause the osteoarthritis on the flat roof of the lumbar centrum, but the intervertebral discs degeneration is the dominative one. In the edge condition, the load on the flat roof of the lumbar centrum deviating from mid to medial results in stress concentration at the medial of the roof of the lumbar centrum. To release this condition, osteoarthritis occurs so as to make the articulation re-stable. In this paper, according to the physiological forming progress of osteoarthritis on the medial edge of the flat roof of the lumbar centrum which is caused by intervertebral discs degeneration, the simulation of osteoarthritis is made on computer from the point of view on biomechanics and physiology through using the bone functional adaptability theory combined with the finite element method.we adopt the force analysis method of lumbar vertebrae put forward by Pawel Kurowski. when a person of a 60 kilograms of weights is standing on one foot, the load and it's distribution on the flat roof of the lumbar centrum , under healthy and degenerated discs condition, are respectively get. Then, according the physiological forming progress and the shape of the spur, we adopt the hypothesis the that was proposed by Liu Baiqi that the pressure distribution on the spur matches the equation: ,in which, "a" is a constant which is related with the shape of the spur and the peak value of the stress on the flat roof of the lumbar centrum, and "b" is the level distance from a point on the spur to the medial edge of the flat roof, the unit is mm.First, we simulated the interior structure and the exterior shape of the lumbar centrum, using a finite two-dimensional element model which takes the shape of a rectangular plate as the initial model form. In the simulation, we take linear bone remodeling velocity equations as the manipulative equation. According to the simulative result of the part, we draw some conclusions as follows: We can simulate the structure of the lumbar vertebrae, through taking linear bone remodeling velocity equation as the manipulative equation, and the simulative structure of the lumbar vertebrae is very similar with the actual structure.Then, we take the simulative structure as the initial model, applying the load when the intervertebral disc is slightly degenerated and moderately degenerated . The load distribution on the spur matches the equation: .So, we simulate the osteoarthritis on the edge of the flat roof of the lumbar vertebrae, by taking linear bone remodeling velocity equations as the manipulative equation.Finally, according to the simulative result of the part, we draw some conclusions as follows:The osteoarthritis can be simulated through using bone self-optimizing theory combined with the finite element method.With the severity of the discs degeneration, the height, width and area of the spur increase.The increase of osteoarthritis is not unlimited, when the spur increase to some extent, the stress concentration is released. The bone structure adapt itself to the loading condition, which makes the Lumbar vertebrae joint reach a new stable condition.Under the intervertebral discs degeneration condition, the abnormal load which is much bigger than the normal occurs more easily. We only consider the normal load in this paper. In the farther study, the abnormal load will be considered. The height, width and area of the spur perhaps increase more ,because of the action of the abnormal load.