7 Points About Personalized Partial Knee Replacements in Surgery Centers

Patient-specific partial knee replacements can provide the same orthopedic benefits as traditional replacements while improving patient comfort and saving surgery centers money and time, according to Jong Lee, senior vice president of marketing and business strategy for ConforMIS.

According to Mr. Lee, patient-specific knee replacements like those made at ConforMIS are designed to fit the anatomy of each individual patient, meaning the shape, size and fit of the implant are based on the articulating curvatures of the knee. Since 2008, most major implant manufacturers, including Smith & Nephew, Zimmer and Johnson & Johnson, have been introducing personalized instruments into the market.

According to Mr. Lee, the orthopedic industry as a whole is moving toward personalized implants. Since 2008, most major instrument manufacturers, including Smith & Nephew, Zimmer and Johnson & Johnson, — have been trying to introduce personalized instruments into the market. Mr. Lee and Joseph Burkhardt, MDDO, of Battle Creek, Mich., discuss seven facts about personalized partial knee replacements in the outpatient setting and why it may be particularly well-suited to surgery centers.

1. Inventory is drastically reduced. Dr. Burkhardt says customized partial knee replacements benefit the ASC by reducing inventory through custom-made implants. "Normally we have to maintain six different sizes, as well as implants for the right and left knee," he says. "The determination of the size is made intra-operatively, so you can end up with an entire roomful of implants that need to be stacked and categorized and maintained for each case you do."

He says the center recognizes a huge savings in both time and cost by using custom implants because the implant arrives in a single pre-sterilized package that's shipped overnight to the center. According to Mr. Lee, the custom-made ConforMIS implants are delivered in advanced of the surgery with implants and disposable instrumentation. He says this method is ideal for surgery centers, which may not have the same "back- up" instrumentation inventory as a hospital.

2. The ASC saves money on sterile processing. Dr. Burkhardt adds that the surgery center saves on sterile processing because the custom-made implants arrive pre-sterilized at the center. "There's only one instrument set, which is the large bone set we use, so there are no implant sets that need to go through sterile processing," he says.  

3. Patients experience less swelling and bleeding.
Patients experience less swelling with the custom-made partial knee replacement because the implant uses a resurfacing femur instead of a geometric-cut femur. The surgeon makes very minimal cuts on the femur because the custom-made implant fits the exact contour of the patient's bone. "When you're using an off-the-shelf implant, you have to have a geometric cut to match your size, so by the nature of the implant not being custom, it requires bone resections to actually get the cut," Dr. Burkhardt says.

Mr. Lee says the custom-made implant also helps the patient avoid bleeding from the rod placed to align the femoral component of the traditional implant. "In some systems, there is a step you do to align the femoral component, where you identify the middle point of the femur and you drill a hole into it and put a lengthy rod up into the femoral canal and the bone narrow canal," Mr. Lee says. "That's a potential source of bleeding and pain, and we avoid all that."

4. Patients must be willing to undergo a CT scan.
While most candidates for a unicompartmental or partial knee replacement are candidates for custom patient-specific implants, one potential limitation is the patient's willingness to undergo a CT scan, Dr. Burkhardt says. "If patients are not interested in undergoing a CT scan to construct the implant, that's the only limit you can really have," Dr. Burkhardt says. He says patients with previous knee implants or replacements may also not qualify for the CT scan, as the metal in the knee can interfere with the quality of the scan.

He says this limitation also applies to patients who don't want to wait the 5-6 weeks required to produce the custom patient-specific implant. "If they say they want to have the procedure done sooner, they'll have to do the traditional procedure," he says.

5. Anesthesiologists must be skilled in regional blocks. Dr. Burkhardt says the surgeon needs to work very closely with the anesthesia department to manage post-operative pain after a partial knee replacement. "They need to have skilled individuals that are very good with regional blocks," he says. Dr. Burkhardt says he has found that the best pain control results from a femoral nerve block.

Don't assume your anesthesiologists are experts in regional blocks if you aren't sure. Sit down with your anesthesia director and discuss which anesthesiologists are appropriate to work on this type of surgery. Then set up a meeting between the surgeon and the anesthesiologist to discuss how the anesthesiologist will manage the patient's pain, as well as his or her expectations for the patient's recovery.

6. Staff needs to be well-versed in handling PKR patients
. The operating room staff and recovery room staff must also be trained in how to handle PKR patients, Dr. Burkhardt says. "The OR crew needs to be familiar with the procedure so the operative time is not prolonged," Dr. Burkhardt says. For example, the OR crew might try minimizing time under anesthesia to assist in the patient's recovery.

The recovery room staff, on the other hand, needs to be very focused on the goal of post-operative recovery and mobility training. The staff needs to be able to teach patients how to utilize their walkers, get in and out of the bathroom and get up and downstairs. "It's not very complicated, but it needs to be thought out — the patient needs to be educated before they leave the center," he says.

7. Certain patients are not appropriate for PKRs.
While most knee replacement candidates are good candidates for PKRs, certain patients are not appropriate for the surgery in an ambulatory setting, Dr. Burkhardt says. These patients include those with extreme osteoporosis, patients with morbid obesity or patients with deficient anterior cruciate ligaments.

Mr. Lee says total knee replacement has been shown to be a good procedure, studies have shown that many active patients prefer partial knee replacements. He says a good number of knee replacement patients are actually under 65. "I believe around 40 percent of all knee replacement surgeries are done on people under the age of 65," he says. "That's a surprising amount."

Related Articles on Orthopedic and Spine-Driven Surgery Centers:
7 Trends Affecting the Future of Pain Management in Surgery Centers
Key Concepts for Transitioning Spine Surgery to ASCs
Business Strategies for Spine in Outpatient Surgery Centers

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