TEAM EFFORT Nurses and techs with joint replacement experience help ensure procedures go as smoothly and efficiently as possible.

Interested in starting a joint arthroplasty program, but aren't sure where to begin? You might want to first consider unicompartmental knee replacements, which are less invasive than total knees and often performed on younger, healthier patients. Plus, replacing only the diseased portion of the knee is now easier than ever thanks to patient-specific implants, improved instrumentation and robot-assisted navigation. In fact, adding partial knees could be the perfect way to test the outpatient joint replacement waters without getting in over your head.

Docs who do partial knees
To add unicompartmental knee procedures, you'll need to start with finding the right surgeons for the job. That can be tough, because most residency programs don't teach partial replacements and not many surgeons currently perform them.

"Surgeons aren't typically exposed to the required techniques," says Craig J. Della Valle, MD, a joint replacement specialist at Midwest Orthopaedics at Rush and a professor of orthopedic surgery at Rush University Medical Center in Chicago. "And while some surgeons believe in the idea of partial knee replacements, others think you should just go ahead and replace the entire joint."

The procedure is minimally invasive, which makes it a good fit for a variety of patients, says Dr. Della Valle, but they must meet a few requirements. Specifically, patients should have arthritis in only one compartment of the knee and their posterior cruciate ligament must be intact. Patients should also be relatively healthy with few to no comorbidities and a BMI in a healthy range.

JOINT EFFORT Implant manufacturers and makers of robotic-assisted navigation systems are trying to make the procedures accessible to more facilities.

"It's interesting, because partial knee replacement is a good operation for a young, active person with unicompartmental disease, since it gets them up and moving pretty quickly," says Gary Levengood, MD, an orthopedic surgeon at Sports Medicine South in Lawrenceville, Ga., who notes the life expectancy of a partial knee is 20 years. "But it's also good for patients in their 70s or 80s who have unicompartmental disease, because older patients who get the operation to reduce pain in the knee bounce back quicker than they would after undergoing a total joint replacement."

Don't underestimate the importance of having staffers who are familiar with orthopedic procedures, preferably joint replacements, says Dr. Levengood. Since uni knee cases move quickly and involve several intricate steps, it's good to have an experienced OR team that can anticipate what the surgeon needs next and ensure that the room runs efficiently.

Clear Benefits: Why Adding Partial Knees Makes Sense

STARTING POINT Surgeons can get a feel for total knee arthroplasty by first replacing only a portion of the joint.

Although partial knees represent only 6% of all primary knee replacements performed today, an increasing number of surgeons who operate on uni knee patients are looking to discharge them on the day of surgery, says Craig J. Della Valle, MD, a joint replacement physician at Midwest Orthopaedics at Rush and a professor of orthopedic surgery at Rush University Medical Center in Chicago. "Many surgeons like myself who want to start doing joint replacements on an outpatient basis start by doing partial knees in the surgery center setting," says Dr. Della Valle.

The procedure is minimally invasive, because patients ideally suited for the surgery present with cartilage degeneration in only one compartment of the knee, typically on the joint's lateral or medial side, says Dr. Della Valle. Instead of replacing the entire joint, the surgeon removes only the diseased cartilage and bone, while preserving the ligaments that help support the joint. The surgeon then places an implant to take the place of the removed anatomy.

For outpatient facilities, the big draws of uni knees are that they require less equipment than total knees and they offer significant profit potential. Profit margins as high as 40% on uni knee procedures performed in an ASC are not uncommon, says Gary Levengood, MD, an orthopedic surgeon at Sports Medicine South in Lawrenceville, Ga.

It's a great option for your patients, too. Dr. Levengood says patients tend to recover quicker, are more satisfied with the surgery and have a more natural movement in their joint compared with patients who undergo a total knee replacement.

— Kendal Gapinski

OUTPATIENT OPTION An increasing number of surgeons who perform partial knee replacements want to do them in the ambulatory setting.

Selecting the implant system
Once you have the right surgeons, staff and patients, you're going to need to stock the right uni knee system. You have plenty of options. From standard off-the-shelf implant systems to advances in robotic-assisted navigation, manufacturers are trying to make the procedure more accessible to more facilities. Here are some factors to consider when deciding which implants to buy.

• Stock options. In recent years, several off-the-shelf unicompartmental systems have upgraded their instruments and cutting guides, says Dr. Della Valle. The latest uni systems also tout new drill guides that allow for more precise implant alignment, fewer instruments for improved case efficiency and smaller, better tools that let surgeons balance flexion and extension gaps to restore the knee's normal ligament tension. Additionally, several systems now boast more-forgiving designs, says Dr. Della Valle, so surgeons can insert implants with a few degrees of misalignment and patients may still have good outcomes.
• Fixed or mobile? Implant designs vary, but one important distinction is whether the implant is fixed-bearing or mobile-bearing, says Dr. Della Valle. Mobile-bearing implants feature a polyethylene insert that can rotate a few degrees in the tibial tray. These tend to be more technically challenging to implant, but the wear rate is very low. Fixed-bearing implants have the polyethylene component in place and tend to be easier to manipulate, though they typically have a higher rate of wear. "Both styles of implants have excellent results," says Dr. Della Valle. "The decision of which one to use typically comes down to surgeon familiarity. They get comfortable with a certain implant or technique in their residency and tend to stick with that."
• Reprocessing needs. One factor that can impact your choice of unicompartmental knee systems is the size and capacity of your facility, says Dr. Levengood. While partial replacements require less instrumentation than total joints, your surgeons may still need several large trays of power tools and instruments to implant conventional off-the-shelf systems. Smaller, more streamlined facilities might be better served with patient-specific implant systems that include single instrument trays, cutting guides and the implants needed for individual patients, says Dr. Levengood. For patient-specific systems patients must get a pre-op CT scan, which the implant manufacturer uses to create a customized implant and cutting jig. The manufacturer sends the jig, implant and tools for the procedure to the facility in a single box.
  

  Patient-specific implant systems help to control your supply inventories. "You don't have to use the standard heavy instrumentation, which means you don't have to sterilize all those tools," says Dr. Levengood. "If you're trying to boost turnover times and move cases through more efficiently, reprocessing numerous trays of complex instruments can be a hassle." With patient-specific systems, everything the surgeon needs arrives pre-sterilized and is disposable, which makes setting up cases and cleaning rooms between cases a lot simpler.

• Patient-specific components. In addition to patient-specific implants, some manufacturers offer patient-specific cutting guides. Patients undergo a pre-op MRI or CT scan, which manufacturers use to design a custom, disposable cutting jig that guides the surgeon's cuts in the bones of the joint to improve the fit of an off-the-shelf implant. Though studies haven't definitively shown that patient-specific implants and cutting jigs perform better than conventional surgery, they can reduce blood loss and minimize the amount of bone removed, which ultimately reduces post-op pain and improves outcomes, says Dr. Levengood.
• Robotic assistance. Robotic-assisted unicompartmental knee replacement is another option to help boost a surgeon's accuracy. Surgeons use a handheld navigational device that shows a 3D intraoperative map of the patient's anatomy. This map lets the surgeon know exactly where he needs to make cuts to precisely fit the uni implant, says Dr. Della Valle. The goal with robotic-assisted systems is better post-op joint alignment, although studies haven't proven that this translates to improved patient outcomes. "Can you get a better cut with a robot? Probably," says Dr. Levengood. "Does it matter? Probably not. We're talking micrometers."

While novice surgeons may benefit from the increased accuracy, robotic systems may slow experienced surgeons down. "The problem with robots is that they're cumbersome, they're expensive and we don't yet know about the long-term benefit of using the technology," says Dr. Levengood.

Assess surgeon preferences
"Some surgeons believe in patient-specific systems and robots, and some don't," says Dr. Della Valle. "Many of us have gotten sensitive about value, and these technologies cost more money. Plus, it's been hard to show that they improve durability of the implant and how the patient feels after surgery."

Ultimately, the type of uni system that ends up on your shelves will depend on surgeon preference, says Dr. Della Valle. Your best bet is to have a frank conversation with your surgeons to find out which system they prefer, and to work with them to determine if it will help achieve good patient outcomes without breaking the bank. OSM