Speaker: Prof. Edmund Y. S. Chao

Orthopaedic Biomechanics Laboratory

Johns Hopkins University

Abstract:

Renaissance is the term used to signify the rediscovery and utilization of old culture, inventions, principles and techniques. It is also a universal meditation for artistic and technological innovation. Musculoskeletal biomechanics has a parallel development history with that of CAD/CAM and the latter was initiated in the 1960’s and expanded exponentially in the 1990’s to establish today’s CAE (Computer-Aided Engineering) allowing seamless integration of analysis packages, interactive simulation software, image rendering, robot and tooling station, and animation. Musculoskeletal biomechanics started its extensive investigations in the 1960’s although the original concept of applying the engineering mechanics principles to study human movement can be traced back to the time of antiquity. A full expansion of its scope to incorporate different branches of mechanics on all connective tissues took place in the 1980’s and 1990’s.  Existing theories of mechanics and their appropriate extensions were applied. While breaking new grounds in the basic understanding of the structure and function of connective tissues, biomechanicians were also able to challenge the tradition fields of applied mechanics by introducing new theories and classes of problems. Among these, the inverse dynamics problems, the biphasic theory of fluid/solid interaction, the regeneration and remodeling hypotheses of connective tissue under biomechanical environment, and the uniqueness of finite angular displacement in articular joints are only a few examples. The evolutions in both fields can be regarded as a “Neo-Renaissance” in computer-aided engineering analysis and simulation.

Biomechanical modeling and analysis at the organ and system level are still limited by the anatomic complexity and the lack of the basic understanding of its control mechanism. Motivated by the recent advances in MCAD and simulation technology, the concept of Virtual Interactive Musculoskeletal System (VIMS), a subset of the grand vision of “Virtual Human”, was developed. “Virtual” model and environment can be combined with the “real” pathology and deformity to form a “hybrid reality” for biomechanical analyses to study the bone and joint deformity and degeneration processes, their functional effects, and the associated treatment rationales. VIMS applications included research, education and clinical patient care. Such technology underscores the critical importance of preoperative planning, prosthetic device design and application, and the optimal execution of the reconstructive surgery. The human musculoskeletal joint structure and geometry can be obtained from CT and MRI, while the kinematic and loading data are measured experimentally. The true 3D surface or solid models of human bone, joint, ligament, musculature, and the reconstructive devices with realistic anatomic features, accurate shape, size and material properties provide the ideal tools for basic science research, medical education, skill training. VIMS-Model is to create biomechanical models to facilitate the required analyses.  Biomechanics-based treatment planning using the computational capability of the VIMS software (the VIMS-Tool) for surgical execution monitoring should improve clinical outcome in patient care.  The Virtual Interactive Musculoskeletal System can be used to conduct static, dynamic and fatigue testing while allowing results to be visualized together with the model.  Combined with the environmental and loading conditions, a Virtual Testing Laboratory (VIMS-Lab) can be created on computer work stations to allow repeated testing of implant devices and surgical reconstruction options under unlimited functional and clinical scenario as an ultimate application in orthopaedic surgery and rehabilitation.

The robust modeling library and analysis toolbox combined with the graphic presentation and animation capabilities, surgical planning can be customized and optimized. To execute the operative or therapeutic plan, a new field of computer-aided orthopaedic surgery, the CAOS, has emerged. Relying on image or marker-based navigation system, skeleton tracking, bone bed preparation, implant positioning can all be performed safely and efficiently with precision. Added by archived generic models, individual patient’s CT scan, parametric scaling and image merging techniques, surgical or therapeutic interventions can be implemented under a hybrid reality environment. Similar technology can also be used to facilitate effective and safe rehabilitation, a spin-off bioengineering technology, CAR (Computer-Aided Rehabilitation). The use of VIMS and CAOS/CAR technologies will undoubtedly re-discover the eminent importance of biomechanics not only for the fundamental understanding of musculoskeletal system function, but also for direct patient care for treatment outcome quality control while achieving cost containment. Can VIMS revolutionize orthopaedic surgery and hehabilitation the same way CAD/CAM did for engineering? To answer this question will require fully appreciation and equal support of the vision “Physiome” – a true Renaissance in utilizing engineering analysis to understand human physiology in a relevant and cost-effective manner!

Brief Biography:

Edmund Y. S. Chao received his BS degree in Agricultural Engineering from the National Taiwan University in 1960 and the MS degree in Agricultural Engineering with a minor in Mechanical Engineering from the Virginia Polytechnic Institute in 1964.  After that, he worked as a senior engineer at the Research and Technical Center of Deere & Company in Moline, Illinois from 1964-1968.  He then entered the University of Iowa and pursued his PhD in Applied Mechanics from 1968-1971.  He remained there as an Assistant Professor in the Department of Mechanics and Hydraulics for one year and moved to the Mayo Clinic and created its first Biomechanics Laboratory while serving as a Consultant in Orthopaedics and Professor of Bioengineering from 1972-1992.  In 1993, he joined the Johns Hopkins University as a Professor of Orthopaedic Surgery and started a new biomechanics research program and has been the Vice Chair of Research in the Department.  He also holds adjunct appointments in the Departments of Biomedical Engineering and Mechanical Engineering at Hopkins.  His primary interest is to develop virtual human musculoskeletal simulation models for dynamic analysis of their internal forces, joint pressure distribution, ligament tension, and the state of stress and strain in the bone in response to activities.  He has also worked in the fields of bone fracture and/or defect repair augmentation, and the reconstruction of segmental bone and joint defects after resection of bone tumor or in joint replacement revision surgery with massive bone defect.  He has trained many physicians, scientists and engineers to utilize the knowledge of biomechanics and biomaterials to enrich their teaching, medical practice and research career.  He was able to apply engineering principles and technologies to benefit several other medical and dental subspecialties in their teaching, research and patient care.  He serves as a role model for those with an engineering education and training who wish to pursue a rewarding career in a clinical department and being accepted as a colleague by his medical peers.