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We have developed a new finite element (FE) model of human right ear, including the accurate geometry of middle ear ossicles, external ear canal, tympanic cavity, and mastoid cavity. The FE model would be suitable to study the dynamic behaviors of pathological middle ear conditions, including changes of stapedial ligament stiffness, tensor tympani ligament (TTL), and tympanic membrane (TM) stiffness and thickness. Increasing stiffness of stapedial ligament has substantial effect on stapes footplate movement, especially at low frequencies, but less effect on umbo movement. Softer TTL will result in increasing umbo and stapes footplate displacement, especially at low frequencies (f1500 Hz. As (TM) thickness was increased, the umbo displacement was reduced, especially at very low frequencies (f

Disc degeneration and osteoporosis are two main factors affecting the elderly and impacting the quality of life. The aims of this study were to provide the information on mechanical changes resulting from disc degeneration and osteoporosis and further to understand their roles in segmental instability. The influences of disc degeneration and osteoporosis were investigated using a 3‐dimensional finite element model of an L3‐L4 two‐vertebral unit under compression, flexion, extension and torsion loading. The different levels of osteoporosis and disc degeneration were performed in the simulation model. From the results, we noted that disc degeneration had much more effect on the effective stress concentration on the articular facet and downward displacement under compression. Under compression, disc degeneration also had great influence on the forward displacement of the upper vertebra and disc bulging. Severe osteoporosis would significantly change the strain energy distribution in cancellous bone ...

The consensus of the normal magnitude of lumbosacral curve has not been achieved. The Cobb's angle cannot depict the whole contour of this curve. For practical applications, a clearer image of these curves and their aging changes should be further investigated. This study aimed to provide a more consolidate concept of normal lumbosacral curves for clinician through a computerized reconstruction method. Standing lateral radiographs of lumbosacral spine in 82 normal adults were used for reconstructing the sagittal lumbosacral curves. The geometric characteristics of these curves according to the gender and age groups were studied. Using standing lateral radiographs, reconstruction of the lumbosacral curves was performed through digitization, programming and computation. These curves and related parameters were normalized and averaged for analyzing the differences of gender and age. The most anteriorward and horizontal vertebrae usually occurred on the L4 and L3 in any gender and age groups. The sacral inclination angle did not change obviously with the increasing ages. A tendency of L1 shifting backward was noted in the age groups of 40 to 60 and above 60 years old. The sagittal lumbosacral curves can be easily reconstructed by digitizing lateral radiographs, The aging changes of lumbosacral curves could be qualitatively described as the flattening of lower lumbar curve and the rearward inclination of upper lumbar curve. The changes occurred obviously above 40 years old. Although individual variations existed, the aging changes and the geometric characteristics such as the most anteriorward or horizontal vertebrae could be used as an important guideline during therapy or surgical correction.

Neurosurgeons are required to perform craniotomies to remove brain tumors, hemangiomas, cerebral aneurysms, blood clots in the brain, or relieve internal pressure in the brain. After a craniotomy, the cranial flaps removed from the skull must be set back and fixed appropriately. However, due to the different sizes and shapes of cranial flaps and the various fixation methods, in certain clinical cases, the fixed cranial flaps might be loosened or in dented condition after surgery. This study thus developed a cranioplasty surgical-planning platform to integrate medical imaging technology, computer-aided engineering, and a high-performance computing simulation and visualization. This platform provides an efficient approach to evaluate the structural strength of cranial flaps before an operation. Surgeons can execute preoperative biomechanical simulations of cranial flaps under different fixation methods to achieve optimal fixation planning.