How single-use instruments facilitate jump from inpatient to outpatient total knee arthroplasty

Spinal Tech

A 2016 study published in the Journal of Bone and Joint Surgery predicts total knee arthroplasties will witness a 673 percent boost by 2030. 

In 2026, Sg2 analysts predict 52 percent of all primary knee replacements will occur in an outpatient setting, whether in a hospital outpatient department or ambulatory surgery center. Advancements in perioperative anesthesia and postoperative patient care have yielded reduced lengths of stay as well as decreased complications for TKA patients, according to Sg2 research. 


Driven by such a significant projected boost of total knee procedures, surgeons are seeking innovative technology and techniques to save time, limit processing costs and enhance accuracy when performing these procedures as they transition to same-day surgery and outpatient settings.


Tyler Goldberg, MD, of Austin-based Texas Orthopedics, Sports & Rehabilitation Associates, and Coleman Fowble, MD, of Columbia, S.C.-based Midlands Orthopaedics & Neurosurgery, specifically prefer TKA technology adaptable to the outpatient setting and decided to leverage Medacta's MyKnee Patient Specific Instrumentation in conjunction with Efficiency single-use instrumentation.


When used with Medacta's Efficiency single-use instruments, Medacta's MyKnee patient-matched cutting block technology facilitates implantation of the Medacta GMK Sphere Total Knee Implant System during outpatient or same-day surgical procedures. The combination of these single-use instrument platforms has successfully reduced operative setup and breakdown times, instrument processing costs and time, storage space and weight. Terminally sterile, the platforms also reduce the need for a bulky sterilization unit on the premises.


Drs. Goldberg and Fowble discuss their experience performing TKAs in the outpatient setting with MyKnee PSI and Efficiency single-use instruments in conjunction with the Medacta GMK Sphere Total Knee Implant System. The GMK Sphere is a sagittally stable total knee implant system designed to reduce paradoxical motion and mid-flexion instability, potentially improving patient satisfaction post-operatively.


Question: Why and when did you start using the Medacta platform for total knee arthroplasty procedures? Do you perform the procedure inpatient same-day or outpatient?


Dr. Tyler Goldberg: I started looking at utilizing the MyKnee patient-matched platform in December 2008. At that time, I was performing computer-assisted TKA. With computer-assisted orthopedic surgery, I was able to achieve great accuracy, but at additional expense of time, disposables and complexity to each case. Therefore, I was interested in finding a solution that would bring surgeons the accuracy of computer-assisted orthopedic surgery, but at conventional technique speed. To me, this required removing the computer from the OR and performing all the computer work (planning) prior to the operation.


Medacta then put together a work group with me, Rob Greenhow, MD, and Craig Loucks, MD, both from Denver, and other surgeons in Europe to create what has become the MyKnee platform. I started utilizing the technique in my own patients in April 2010 and use it now for essentially 100 percent of my TKAs. I perform the procedure in both inpatient and outpatient settings.


Dr. Coleman Fowble: I started using the MyKnee platform a year ago this month. I switched because I was having similar results with the knee I was using as reported in the literature, which is only about a 75 percent to 80 percent excellent outcome. I moved over to this technology because I wanted to see if the Medacta MyKnee and Efficiency systems used with the GMK Sphere system would produce superior patient outcomes in terms of function and satisfaction.


In 2013, our group started doing outpatient joints in our surgery center. So, the appeal of this disposable system from a cost standpoint gave me the best of both worlds.


Q: How steep would you say the learning curve is for surgeons using Medacta MyKnee patient matched technology in conjunction with Efficiency singe-use instruments to implant the Medacta GMK Sphere? What is the best way for a surgeon to tackle learning this procedure?


TG: The learning curve for patient-matched technology in my opinion deals with two specific areas. First, is trusting the technology — will the instrument achieve the pre-planned result it was designed for? This natural "mistrust" of the instrumentation will cause the surgeon to do multiple checks and re-checks in their initial procedures to ensure accuracy of the TKA implantation.


Second, is the simple act of registering, or placing, the instrument to the bone. The Medacta MyKnee technique provides pre-fabricated models of the knee so the surgeon can trial the cutting guides prior to registering to the actual bone. Fortunately, both of these areas are learned concurrently and usually require five to 10 cases before trust and comfort with the technique exists. The Medacta Efficiency instrumentation performs remarkably similar to traditional metal instrumentation and has an even shorter learning curve.


The best way for a surgeon to learn the technique is to be methodical. A visit to a reference center to see the technology in another surgeon's hands followed by performing the procedure in a cadaver lab will provide the necessary tools for the surgeon to begin on their journey with the technique.


CF: The incentive of using the equipment is the same, the learning curve has to do with the comfort level with the cutting guides, and it takes a while to get used to especially if you use the CT-produced cutting guides. I like the CT better because you're referencing on bone instead of articular cartilage.


To make this technique reproducible, one should shadow a surgeon to see how the cutting guides are anchored to the bone. Next, you can go to a lab and do the surgery on a cadaver.


Q: Do these instruments facilitate performance of same-day TKA? Why?


CF: Yes. What you're doing is eliminating a lot of the costs of sterilization, and not only from the physical cost of sterilization but the labor costs of getting trays ready; the time component of money and physical cost of sterilization as well. Additionally, there is no cost for storage of the equipment.


There is a safety aspect in an outpatient facility where you want to minimize the risk, so a separate disposable tray is used for each patient. There is more risk of something being reused than brand new.


TG: I have found MyKnee and Efficiency almost invaluable in my ambulatory surgery center to perform my outpatient TKAs. Our surgery center is not designed to sterilize the large, heavy instrumentation sets required to perform these procedures. Additionally, we do not have the space to store the sets for the surgery.


Having pre-packaged, pre-sterilized instrumentation available for these cases allows me to perform these procedures in this setting which I would otherwise not be able to. In addition, the weight of the sets cannot be overlooked. A traditional metal instrument set weighs 74.5 lbs. In contrast, the equivalent MyKnee, Efficiency weighs 5.5 lbs. — a delta of 69 lbs.! This cannot be overlooked in an ASC setting where light, nimble equipment facilitates the day.


Q: Would you recommend the instruments for their accuracy and efficiency?


CF: Yes, very rarely do I have to make a re-cut. Sometimes in patients who have significant varus deformity, I will not use the custom cutting guide; I will use the standard varus-valgus cutting block and not cut as much varus. However, I use the custom cutting guide to mount the pins and then place the standard valgus/varus cutting guide on the pins.


I've never had to re-cut a femur, but have had to re-cut a tibia a few times.


TG: I routinely recommend the technique for both accuracy and efficiency. From my own personal data, I actually improved my alignment with this technique compared to my previous computer-assisted orthopedic surgery experience. My alignment results for my MyKnee patient-matched procedures were 94 percent compared to 92 percent with computer-assisted orthopedic surgery.


My efficiency with my procedures has come not from my own operative times, but from room set-up and turnover times at the end of the case. Recently, we performed a study in which we timed the opening and closing of a room for a TKA procedure utilizing both Efficiency and standard instrumentation. We found a savings of 15 minutes in set-up and 10 minutes in take-down per case — a significant savings of 25 minutes per case!


Q: How many procedures have you performed with the platform?


TG: I began using the MyKnee platform in April 2010. Unbelievably, I have not changed from this technique in seven years. I perform roughly 300 TKAs per year, totaling about 2,000 cases. I began using the Efficiency single-use instruments in May 2013. My first experience was sporadic due to the prototype nature of the initial instruments. Steadily, as production has improved and increased so has my use of the instruments.


I currently use Efficiency instruments in approximately 50 percent of my cases totaling over 500 cases in the last four years. As stated previously, my comfort with the instruments has grown to now I consider them my "standard."


CF: I've performed probably a little over 100 procedures with the MyKnee Efficiency platform. There is a learning curve getting used to removing the articular cartilage to anchor the feet on the cutting guides. Now, I can do this almost as quickly as my previous technique. It can be done off an MRI as well. The instruments are well thought out with some things having multiple uses to limit the number of pieces and operative steps.


Q: Have your patients expressed satisfaction with the GMK Sphere TKA system? Would you say the implant system's inherent stability lends to accelerated postoperative ambulation and discharge?


CF: So far the patients have been happy. I've found that they don't seem to swell as much. With the Medacta system, you don't have to enter the canal of the distal femur and so there's less swelling and they rehab faster. You can see the tibia rotating with the trials mimicking a human knee more naturally.


TG: My heritage for TKA has been to use a PCL substituting "deep dish" implant. As such, I have always been comfortable with releasing the PCL and relying on the design of the implant for the kinematics of the knee. What I noticed very quickly after beginning with the GMK Sphere system was that my patients who would have done well with the deep dish, did exceptionally well with the Sphere. Their range of motion was greater to a point where I noticed patients would routinely kneel and squat, something I did not have before.


I did not change my technique, but only my implant to achieve these results. I believe this is a testament to the inherent stability of the knee. I also believe patients experience less mid-flexion instability with the Sphere and consequently are able to navigate stairs and low-seated chairs more confidently.


I believe these early outcomes derive more from good perioperative protocols for pain control, mobilization and patient education. I routinely perform TKA on an outpatient basis, which is more of victory for my perioperative care than for the actual implant.


Q: Have you found a financial advantage in using the products together? By leveraging the platform, have you also seen reductions in OR time, room turnover time and processing costs?


TG: We recently looked at 100 cases using the MyKnee Efficiency technique versus traditional technique utilizing a Sphere implant. We accounted for several variables to model the potential economic benefit including:


1. Reduced infection risk
2. Operating room time efficiencies
3. Absence of use of the Central Sterilizing Department
4. Loaner tray utilization
5. Cost of the products


Our economic modeling projected a $1,189.10 per case savings when using the MyKnee Efficiency products. As stated previously, we further found a 25 minute per case improvement in case time. Additionally, the Efficiency instruments come pre-sterilized so the CSD is eliminated, which accounted for $700 per case considering the time and number of trays processed.


CF: Yes, [I've seen] some direct and some indirect cost savings. I think at firstyou're not going to see reduction in OR time because of the learning curve. Now, I'm doing the procedure as fast as my previous technique and there is little turnover time because there are no trays to clean up other than a general instrument tray; the rest is disposable.


This article was sponsored by Medacta.


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