New LPS-FLEX Knee Prosthesis

The Insall Scott Kelly Institute for Orthopaedics and Sports Medicine at Beth Israel Medical Center consists of a team of world-renowned orthopedic surgeons including John N. Insall, M.D., Director of the Institute and designer of the Total Condylar Knee Prosthesis which became the first widely used knee implant over 25 years ago. Since then, Dr. Insall and his colleagues have designed many successful variations of the implant. There are over 250, 000 total knee replacements performed annually in the United States and this number doubles when you consider worldwide procedures. Dr. Insall’s designs have been instrumental in the global success of total knee replacement. 

Recently, Dr. Insall and his associate, Giles R. Scuderi, MD, in association with Zimmer engineers, developed an innovative version called the LPS-Flex Knee Prosthesis, which allows the patient’s knee to obtain a normal range of motion. Current knee implants allow no more than 125 degrees of flexion, while the new LPS-Flex Knee provides as much as 160 degrees of flexion. 

Dr. Insall comments, "Current implants are not suitable for patients requiring full motion or whose lifestyle requires full flexion. With an increasing number of active baby boomers considering total knee replacement, this may be the appropriate implant. It is our belief that only this type of prosthesis can successfully replicate normal knee motion. Redesigning the femoral and tibial components along with an improved cam mechanism accomplished the greater range of motion with the LPS-Flex Knee Prosthesis: the unique cam mechanism helps drive the knee into deeper flexion" 

Dr. Scuderi, Associate Chief of Adult Knee Reconstruction at Beth Israel Medical Center says, "While this prosthesis is designed for normal knee motion, it is important to realize that the pre-operative knee flexion will influence the final outcome. Therefore, this implant may not be useful in all patients. But, in developing this knee prosthesis we have also modified our surgical technique to create a flexion-friendly environment for our flexion-friendly prosthesis. This new surgical technique has beneficial implications for all our patients."

The procedure takes about an hour and a half and is performed under an epidural anesthetic. Following the operation, the patients participate in a supervised rehabilitation program, which is specially designed to regain greater flexion. A team of physicians, nurses and therapists guide the patient through their recovery. Most patients are discharged from the hospital in five days and are then followed in the office as an outpatient.