A BETTER FIT Are patient-specific instruments and implants that match the orientation, size and dimensions of the patient's own knee the future of total knee replacement?

Patients who get their knees replaced after enduring years of discomfort should expect to feel like their younger selves again, right? Not necessarily. About one-fourth of knee arthroplasty patients are dissatisfied with the surgery's results, according to Richard G. Buch, MD, an orthopedic surgeon at The Dallas (Texas) Limb Restoration Center. "Often, their pain may be less," he says, "but function-wise the joint doesn't feel like their own knee."

In an effort to reduce the unnatural sensation some patients experience, more surgeons are using advanced imaging and 3D printing to develop customized instrumentation and implants that better fit an individual patient's anatomy. Here's how the technology can improve your OR efficiency and joint replacement outcomes.

A cleaner cut
There are 2 main types of patient-specific total knee systems on the market, says Dr. Buch:

• customized cutting blocks that guide the surgeon while he shapes the patient's knee to fit the manufacturer's off-the-shelf implant; and
• patient-specific implants designed to mimic the patient's unique knee structure.

While a surgeon using standard templates and jigs usually relies on anatomic landmarks to make the cuts in the patient's tibia and femur, patient-specific cutting guides take the guesswork out of the procedure and precisely dictate where to cut the bone for a better implant fit.

The process typically starts with the patient getting a pre-op CT or MRI scan, which is then sent to the implant manufacturer, who draws up a preliminary plan for surgery. The surgeon then logs into a secure system to view the plan and make adjustments as needed. The manufacturer uses the plan to print a disposable cutting block, which is sent to the facility before the case. "In the OR we just open up the box and pin the guides to the femur and tibia to help guide the cuts," says Lee E. Rubin, MD, FAAOS, assistant professor of orthopedic surgery at Warren Alpert Medical School of Brown University in Providence, R.I.

CUSTOMIZED IMPLANTS Using a patient's pre-op CT scans, manufacturers can create an exact duplicate of the patient's knee for the replacement, instead of relying just on conventional measurements.

By pre-planning the cuts, you can save time in the OR and get a more precise alignment in the joint. Plus, some experts believe that you can lower the risk of infection and blood loss, since you're not inserting metal rods inside the bones to guide the incisions as you would with standard instrumentation.

However, Paul A. Manner, MD, FRCSC, joint replacement professor at the University of Washington in Seattle, notes that studies backing up many of these claims are still lacking. "There's no real evidence that customized cutting blocks make a difference in terms of outcomes," he says.

Plus, Dr. Rubin says there are more upfront costs tacked onto the procedure when using the patient-specific instrumentation, thanks to the addition of the CT scan or MRI imaging, as well as the higher price tag for the guides themselves. While you can save time in the OR, surgeons may also have to put in additional legwork before the procedure.

The cutting blocks can be used for nearly any patient undergoing a total knee replacement, but many surgeons are trying to figure out which ones are best served by the technology. "That's the question that everyone is trying to answer," says Dr. Rubin. "If you're going to spend the money on the process and the time it takes to review the plans, it's best for patients with an unusual anatomy or patients with severe deformities."

E-MAIL ENGAGEMENT
Web-Based Plan Keeps Total Joint Patients on Track

DAILY UPDATES The Wellbe interactive fills in information gaps throughout the entire episode of care.

Keeping hip and knee replacement patients engaged is one of the keys to outpatient total joint success. It's also challenging, considering that the entire journey, from pre-op planning to rehab, takes months. You can't be with patients every day, but a Web-based interactive care plan that explains what to expect before, during, and after surgery can.

Wellbe (wellbe.me) is one such Web-based plan. Patients have the chance to get acquainted with the program the day surgery is scheduled. They then periodically receive "care cards" via e-mail. One of the first cards introduces the nurse navigator, who also works to keep the patient informed. The care cards are timed to arrive at appropriate intervals, which is also a plus, says Kate Gillespie, MBA, assistant vice president of the Orthopedic Service Line and administrator of the Joint Replacement Institute at Virtua Health in Marlton, N.J., which began a pilot program with Wellbe last December.

Wellbe is provided to all hip and knee replacement patients at Virtua Joint Replacement Institute at no cost. Patients can access the platform via PC, tablet or smartphone. They gradually learn about anesthesia, what to expect on the day of surgery, what forms they need to fill out, how to make sure their homes are properly prepared for post-op rehab and all the other information that used to have to be packed into a 45-minute discussion with the nurse navigator or classes at the hospital.

The nurse navigator, meanwhile, can use the program to keep track of whether patients are opening the care cards, to make sure that they're reading them and to respond to patient questions. As surgery gets closer, patients receive reminders about arrival times and about not eating or drinking after midnight the night before. There's also a financial component to let patients know how their insurance checks out. The care cards continue to arrive in the weeks after surgery with reminders about exercises and medication, as well as which symptoms are to be expected and which might warrant extra attention.

Some leaders at Virtua wondered how many patients would be technologically sophisticated enough to use the program, but only about 1 in 10 have been unwilling or unable to embrace the technology. "A lot of patients have grandkids and are using Facebook and FaceTime to be able to connect with them," says Ms. Gillespie. "So, they get it."

— Jim Burger

One step further
Dr. Buch says 3D-printed patient-specific implants designed to uniquely fit a patient's anatomy are generating a lot of buzz. Like the cutting blocks, customized implants require patients to undergo a pre-op CT scan. The implant manufacturer then uses the scan and special computer software to design the unique implant and customized cutting blocks. The implant is then created using 3D-printing technology. It arrives at your facility in a single box along with all of the instrumentation your surgeon needs for that patient's case. The entire process takes roughly 6 weeks.

Dr. Buch initially focused on younger, healthy patients when he began using the technology, but has since seen the advantage of using it in an increasing number of patients. His research compared standard off-the-shelf implant systems with patient-specific options. Patients who received the customized implants had better outcomes, recovered more quickly and did not require blood transfusions, and their recovery time to walk without aids was about 4 weeks, roughly half as long as the patients who received standard implants.

Dr. Manner notes that the kits often work well for facilities performing a low volume of total knees, especially smaller ASCs or those just starting out with total joints, and eliminate the need to buy several trays of the expensive tools used in arthroplasty.

Dr. Buch says the technology does cost a couple hundred dollars more than standard implants, in addition to the extra cost of the pre-op imaging. "But, if you factor in the cost of a longer hospital stay and the lack of reprocessing, you could be saving money in the long run," he says. Dr. Manner suggests looking at potential cost savings versus the additional upfront costs. He also notes that some surgeons may not like the lack of flexibility offered in these options.

Increasing patients' post-op comfort outweighs any potential challenges, says Dr. Buch. "One guy went skydiving after getting his new knee," he adds. "Sometimes patients go back to thinking it's their normal knee too soon." OSM