Professor Bartel's efforts are generally concerned with the mechanics of the musculo-skeletal system, with special emphasis on the analysis and design of bone-implant systems, including total-joint replacements. When natural joints become damaged due to disease, trauma, or normal wear and tear, the joint surfaces may be replaced with prosthetic components. In most prostheses, one articulating surface is metal; the other is polyethylene. The replacements must provide kinematic function and be able to transmit loads that reach several times body weight during the activities of daily living. The components are fixed to the bone using polymethylmethacrylate to fill the space between the bone and the device, or by bony ingrowth into a porous layer on the device. Ideally, the resulting structure should last the lifetime of the patient. Bartel's work at Cornell concerns the analysis of these composite structures, the development of design criteria for total joint replacements, and the optimal design of these systems. Stresses between the articulating surfaces are particularly important. Damage produces debris, which can migrate to surrounding soft tissue. When the body reacts to this debris, it releases agents that attack the bone-implant interface, and this may increase the risk of loosening and infection. These problems are especially challenging because the shape and material properties of bone change with the passage of time and with changes in loading conditions; interfaces, particularly those for cementless fixation, also evolve; and implant materials such as polyethylene degrade with time in the body. His group makes extensive use of numerical stress analysis and optimization techniques to study how the composite structure, its components, and its interfaces behave through time. This knowledge is then used to develop designs that extend the lifetime of the bone-implant system.

After studying mechanical engineering at the University of Illinois, Bartel taught engineering, mathematics, and physics at Black Hawk Junior College in Moline, Illinois, for two years before beginning doctoral studies in mechanics and hydraulics at the University of Iowa. He joined the Cornell faculty in 1969. Bartel was a Guggenheim fellow and visiting scientist in the Department of Orthopaedics at the Mayo Clinic, in Rochester, Minnesota, in 1976-77. In 1976 he was appointed visiting scientist at the Hospital for Special Surgery in New York City, the orthopaedic affiliate of Cornell University Medical College, and in 1977 he became director of the Cornell-Hospital for Special Surgery Program in Biomechanical Engineering. He now holds a joint appointment as a professor at the Cornell College of Engineering and as a senior scientist in the Department of Biomechanics of the Hospital for Special Surgery.