Dang Orthopedics uses computational modelling and mathematical simulation to study the biomechanics of surgery. Working in collaboration with researchers at the University of California, San Francisco and the New England Musculoskeletal Institute at the University of Connecticut Health Center, Dang Orthopedics is studying the biomechanics of the spine and shoulder through realistic mathematical representations of human anatomy.
When conservative therapies have failed to treat pain or weakness caused by mechanical deformation or inflammation of the nerve roots in the cervical spine (the neck), surgeons may turn to 'discectomy and fusion', where the disc between the affected vertebrae is removed and the spine is then stabilised using bone graft or metal plates and screws. Although this operation has excellent outcomes overall, accelerated arthritis in the rest of the spine is a potential future complication. Surgeons hypothesise that increased strain in the remaining motion segments of the spine after surgery contributes to the accelerated arthritis, but research has been difficult due to the inability to measure this change in strain in actual patients and the limitations of testing with anatomic specimens.
An accurate computational simulation of the stresses on the cervical spine following surgery was needed to determine the biomechanical consequences of discectomy and fusion. Dang Orthopedics developed a computational model of cervical spine fusion using Toyota's Total Human Model for Safety (THUMS) technology. Originally developed to simulate the effect of automotive accidents on the body, THUMS is one of the most sophisticated 'whole human' finite element models in use today, with more than 91,000 individual elements. Dang Orthopedics is the first orthopedic research lab in the United States to receive an academic licence for THUMS and to adapt the automotive engineering tool to general orthopedic research.
Once Dr Dang had the cervical spine model complete, he used LS-DYNA, an advanced multipurpose simulation tool, to isolate the biomechanical effects of single- and two-level cervical spine fusion. LS-DYNA was originally developed by the US Department of Energy and Lawrence Livermore National Laboratory for nuclear weapons development and certification.
Working with these sophisticated tools requires high-precision, scientific visualisation and a complex software development environment throughout the entire development process, from conception to post-simulation data analysis. The size and number of the models that needed to be loaded simultaneously, the computational burden, and the need to view the final results on multiple, high-resolution monitors meant that Dang Orthopedics needed a high-end, professional graphics solution for its systems. The choice was Nvidia professional graphics technology and Nvidia multi-display technology, the solution that provided the graphics horsepower, stability, and visual fidelity.
As a result of Dr Dang's research, surgeons have quantitative data on the biomechanical effects at the adjacent motion segments following cervical spine fusion for the first time. This information will guide future research in the area of multi-level artificial vertebral disc replacement and hopefully reduce the incidence and severity of post-surgical complications like accelerated arthritis.
