"Smart" instrument addresses the largest unsolved problem in hip replacement surgery
BOSTON, Oct. 18, 2011 /PRNewswire-USNewswire/ -- A "smart" surgical instrument, the HipSextant™ Navigation System, was used commercially for the first time on Monday, October 17, at a New York hospital. The system is designed to assist surgeons in placing the artificial implant's cup—the hip socket component—into the pelvis with greater precision during hip replacement surgery.
Studies have shown that cup malposition occurs in 50-80% of hip surgeries performed with traditional techniques. It is one of the leading reasons for hip revision surgery—the surgery required to repair a hip implant that has loosened or dislocated. Among Medicare patients alone, hip revision surgery costs more than $500 million each year.
"Improper positioning of the cup is the largest unsolved problem in hip replacement surgery," says Stephen Murphy, MD, the orthopedic surgeon who invented the HipSextant Navigation System. "The challenge for surgeons is, if you don't know exactly where the pelvis is in space, you can't possibly know exactly how to align the implant." The Navigation System, which can be adjusted for a specific patient, solves the problem. Once the three legs of the instrument dock onto the pelvis, a direction indicator points in the direction that the surgeon has designated as the desired orientation of the artificial cup. Surgical Planning Associates, Inc., has received Class II FDA clearance for the system as a patient-specific manual navigation instrument.
Winshih Chang, MD, an orthopedic surgeon with training in biomedical engineering, used the new system to perform hip replacement surgery on a 74-year-old man at Putnam Hospital Center in Carmel, New York. "It is a simple, elegant and reproducible way to approach placement of the implant cup," said Dr. Chang. "In using the device, I was impressed by the thought and planning that went into its development."
Dr. Chang will use the HipSextant Navigation System again soon. "I have another patient on the schedule and will use it for that case," he said. "I believe the device represents a significant improvement in patient care."
Traditional computerized navigation systems also can lead to better cup positioning. However, during the past decade, many surgeons have turned away from these systems, mainly because they are expensive, complex and time-consuming to use. "Surgeons have essentially voted on the issue by abandoning the use of computerized surgical navigation systems whenever simpler solutions are available," says Dr. Murphy, who is past-president of the International Society for Computer Assisted Orthopedic Surgery. "Our goal was to incorporate patient-specific information into an instrument that is simple to use and that fits naturally into the normal sequence of the surgery, rather than disrupt that sequence."
The HipSextant Navigation System uses a low-dose CT study of the patient, which is uploaded to the product website, where a 3D model of the patient's hip is created. The software also predicts the precise way the instrument will dock on that particular patient. The surgeon downloads and opens the 3D plan, using software that runs on any desktop or laptop computer, and can then adjust the plan to input the desired cup orientation. This determines the exact settings on the instrument.
The new technology has been proven to be significantly more accurate, not only compared to traditional surgery techniques, but also when compared to established computer-assisted surgery methods. Jens Kowal, a Ph.D. in biomedical computing, collaborated with Dr. Murphy on the software and website for the instrument, which is reusable and can be adjusted for use with all patients.
The number of joint replacement surgeries performed in the U.S., including hip replacements, is projected to grow steadily during the coming decade or two. Factors for this growth include the desire by baby boomers to maintain active lifestyles.
Dr. Murphy, an orthopedic surgeon at New England Baptist Hospital in Boston, Massachusetts, and an Associate Professor at Tufts University School of Medicine, has invented surgical methods, instruments and implants to improve hip surgery for more than 25 years, since his medical student days. Among his numerous patents is a minimally invasive surgery technique called the superior capsulotomy. The surgery technique allows most patients to safely return directly home just a day after a hip replacement.
If their implants are placed correctly, those patients may well avoid the need for hip revision surgery. "Revision surgery is complex and costly, not only to society but especially to the patient," Dr. Murphy notes. "Improving outcomes in the simplest way possible is what this work is all about."
For more information, please visit www.hipsextant.com.
SOURCE Surgical Planning Associates, Inc.