The demand for orthopedic joint replacement implants, which has never been greater, is fueling innovations in biomaterials and design to meet the ever-rising expectations of the younger and more active patients avidly seeking these surgeries. New Jersey Institute of Technology alumnus Robert C. Cohen ’83, ’84, ’87, who been involved in creating advanced materials and breakthrough designs to meet the clinical requirements of hip and knee orthopedic implants for the past 30 years, is one of the field’s cutting-edge developers.
"People are living longer, are active longer, and are employed longer. Implants are increasingly integral to quality of life by relieving pain and allowing people to return to work, among other important activities,” Cohen notes. “In the 1980s – the early days of implant technology – the idea was to permit basic functioning, such as getting out of bed or into a car. Today people are returning to tennis and golf. They want back everything they had in life with the relief of joint pain."
In his latest venture, Cohen has added a novel material onto a hip implant, while using intraoperative robotic assistance for bone preparation and implant placement. The concept, he explains, is to allow the implant to be placed into the patient’s bone in a position that best matches the individual’s need to ensure proper joint motion. Once accurately secured, the implant provides for both initial stability and longer-term biologic fixation.
The implant has a porous metal exterior surface pattern that can only be made by a new class of manufacturing called “additive manufacturing.” It is produced by a process known as “direct metal laser sintering” in which a laser is programmed to consolidate titanium alloy powder in a configuration that engineers create with a computer model. The resulting structure is fully solid internally with an external surface porous enough for new bone to grow into. Cohen’s company, Pipeline Orthopedics, based in Cedar Knolls, NJ, was the first in the United States to receive an FDA hip or knee implant approval to use this laser manufacturing process.
With an evolutionary implant in development, Cohen sought out the optimal surgical technique to position the implant in a way that would maximize the potential for joint motion restoration. His company entered into a strategic alliance with Mako Surgical Corp. of Ft Lauderdale, Fla., which provided the use of a robot in the operating room. The haptic, or tactile feedback technology, robot is programmed to the patient’s CT scan prior to surgery. During the procedure, the robotic arm holds the preparation instruments and ensures accurate and precise placement of the implant according to the patient’s specific anatomy.
The combination of additive laser sintering manufacturing to make implants in configurations not before possible and the use of a robot for implantation has given rise to new product development projects. This direction is deemed by many in the medical device industry to be the future of orthopedics.
Cohen’s company, Pipeline Orthopedics, was acquired by the robotic company Mako Surgical last October. Two months later, the New Jersey orthopedic giant, Stryker Corp, acquired Mako Surgical for $1.65 billion. Cohen is now the general manager of Stryker’s robotic and advanced implant business unit, newly named Stryker Mako.
The evolution of Cohen’s technology-based prosthetic devices is a distinctly New Jersey story in which NJIT faculty and students play an important role. Cohen, a graduate of NJIT’s Newark College of Engineering (NCE), credits the college for his beginnings in the medical device business.
"I was very fortunate to have a professor my senior year who was involved in developing medical devices,” he notes, recounting his work with Michael Pappas '59, '64, emeritus professor of mechanical engineering, on the designs for knee, hip and shoulder implants produced by a company Pappas co-founded. That company came up with innovations such as the famed New Jersey Low Contact Stress Knee, still marketed by Depuy as the LCS Knee. Cohen employs many NJIT graduates and has hired student interns for many years. He maintains a close connection with the college, where he now serves as the chairman of the NCE's Board of Visitors and vice president of the Alumni Association.
"In the world of medical device technology, we are living in exciting times. Technology is evolving at a fast pace. We have the power to quickly adapt robotics, additive manufacturing, and new materials to greatly benefit orthopedic patients like never before,” Cohen says. “We must use all the resources at our disposal. NJIT and academic research play a principal role here. Engineers like me in industry know that partnering with the college allows us to stay at the forefront of innovation."