Let’s look at alignment. Neutral mechanical axis alignment. Customized knees are like doing all the navigation pre-op. You don’t need to do any planning. It’s already computer-planned for you. Customized knees are 1.8 times more likely to be within 3 degrees (Ivie, et al., JOA, 2014; Levengood, et al., J Knee Surgery, 2017).
Better fit. Significantly less underhang, and no overhang (Schroeder, J Knee Surgery, 2018).
No lift-off in early to mid-flexion (Zeller, et al., JOA, 2016). We know this is an indicator of mid-flexion instability.
Data on 740 patients from 11 centers showed improved walking time, timed up and go, and timed up and down stairs. When we take this data and combine it into the ALF [Aggregated Locomoter Function] score, we see that custom knee outperforms off-the-shelf components as well, which is a validated measure (O’Conner, ICJR Pan Pacific 2016).
Better fit translates into higher patient satisfaction. A 70 patient study using the Knee Injury and Osteoarthritis Outcomes Score reported higher patient satisfaction (Katthagen, et al., ICJR WAC 2015). Again, 70 patients, so we do need bigger numbers, but this is really strong data.
Finally, another study, this time 360 patients with custom implants—92% satisfaction at 1 year, 90% at 2 years (Tait, et al., ICJR Pan Pacific 2016).
Fascinating data from Dr. Dan Dunaway’s practice in Ohio. Forty-seven of his patients received an off-the-shelf first knee and then he did their second knee with a customized implant. Here are the outcomes in these bilateral patients. Improved KOOS Jr. and Forgotten Joint Scores for the customized implant. When he asked his patients which knee felt more normal, 70%, serving as their own control, favored the custom knee. Overall, 72% of them favored the custom knee compared to 6% favoring the off-the-shelf and the rest were neutral.
Finally, about the cost. Three studies show that custom knees can drive savings for both hospitals and insurance providers. If you’re in a bundle and looking at the economic implant, this is another reason to consider custom knees (O’Connor, et al., AHDB, 2018; Buch, et al., Culler, et al., Arthroplasty Today, 2017).
There is no debate. Custom made total knees produce superior function and patient satisfaction. Patients as their own controls feel the difference and favor their custom total knees. And there is a growing body of evidence for increasing patient satisfaction, while lowering the economic burden of total knees.
Dr. Lewallen: I can always count on Seth (the founder and organizer of CCJR) to give me a curmudgeon talk. He counts on me to be opposed and hostile, so I’ll try to do that.
We keep hearing about the high rates of dissatisfaction with total knee arthroplasty. The theory—which is completely unproven—is that this is due to compromises in implant design, size and shape options. It’s all about the hardware, right? If we could just optimize this a little more, then we’d reach nirvana.
First of all, bad outcomes compared to what? Primary total hip? Ok, maybe a little. Internal fixation of plateau fractures? My total knees look pretty good compared to my plateau fractures. Lumbar fusion for back pain? Anybody else think that’s a superior procedure? Limb salvage for malignant tumors? Pancreatic cancer?
It’s really the expectations you set and we’ve been complicit on moving the dial and creating really unreasonable expectations for many of our patients. Part of the problem is the rapid recovery thing, the minimally invasive procedures, outpatient, marketing hype.
“Come see me and we’ll have you bowling in 3 days.” I think it’s the wrong message for many of patients and it really sets them up for failure.
