Study detects differences in patient-reported outcomes for robotic vs manual TKA
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Mixed differences in patient-reported outcomes were seen for patients after total knee arthroplasty performed with robotics vs. without robotics, according to published results.
Jonathan H. Shaw, MD, Jason J. Davis, MD, and colleagues reviewed 1,160 consecutive patients in the prospective Michigan Arthroplasty Registry Collaborative Quality Initiative database who underwent robotic (Mako, Stryker; n=260) or manual (n=900) TKA from December 2017 to October 2019. The goal of the study was to determine whether patients who underwent robotic-assisted TKA showed higher rates of early and intermediate postoperative improvement in minimal clinically important differences (MCIDs) for patient-reported outcomes compared with patients who underwent manual TKA.
“Exclusion criteria I want to emphasize is that any patient who did not have an early outcome was excluded from our database. Early outcomes were defined 2 to 6 weeks postoperative and intermediate outcomes were defined as 4 to 8 months postoperatively. We defined our MCID as one-half the standard deviation of the preoperative scores,” Shaw said at the American Association of Hip and Knee Surgeons Annual Meeting, where he presented the results.
MCID achievement
Primary outcome measures used included the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and patient reported outcomes measurement information system – global health (PROMIS-GH) scales, which include PROMIS physical health (PH) and mental health (MH) scales.
“When it comes to PROMIS physical health, you do see the similar trending increases in postoperative scores like you do with KOOS JR scores,” Shaw told Orthopedics Today, but noted this trend did not hold true regarding the PROMIS-MH scale score.
“Multivariate analysis showed similar short-term and intermediate MCID achievement in these patient-reported outcome systems and there are some interesting findings in the low preoperative performers vs. high preoperative performers that should be included in future studies when looking at these patient-reported outcome systems,” he said at the meeting.
Investigators saw a statistically significant improvement in MCID achievement for the early KOOS JR scores that favored manual TKA. However, when it came to the multivariate analysis, this did not hold true.
“There was a significant improvement in mean scores for PROMIS mental health in robotic total knees compared with manual total knees, but the MCID achievement did not show any significance,” Shaw said.
The single-surgeon subanalysis demonstrated PROMIS-PH MCID achievement that favored robotic-assisted TKA in the early postoperative period, which, Shaw said, shows how confounders from the multi-surgeon database used may cause skewing of the data. Therefore, a large single-surgeon database may be necessary to control for these confounders, he said.
Controlling for variabilities
Shaw told Orthopedics Today results of this study reflect some of the variabilities that need to be controlled for in future research to provide a good conclusion. This is especially the case with early reported outcomes that may indicate a subtle difference between the manual and robotic TKA cohorts, he said.
“If you have these differences ... it is probably going to be subtle and, if that is the case, then any type of confounders that you can find that would skew the data, can skew it one way or the other. So, you may have to have a pure study that controls for that,” Shaw said.
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Reference:
- Shaw JH, et al. Paper 22. Presented at: American Association of Hip and Knee Surgeons Annual Meeting; Nov. 5-8, 2020; Dallas (hybrid meeting).
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For more information:
- Jonathan H. Shaw, MD, can be reached at Henry Ford Hospital, 2799 W. Grand Blvd., Detroit, MI 48202; email: jshaw5@hfhs.org.
Perspective
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This study is yet another in the rising number of studies evaluating robotic- assisted TKA. The strengths of this study are its prospective nature, as well as highlighting MCID between the groups.
That being said, the study found a significant difference at one timepoint on one patient-reported outcome favoring robotics of all those studied. This, honestly, does not surprise me at this time.
Robotic-assisted surgery will certainly have a place in the future of TKA. I do think that outcomes presently lag a bit behind the technology. It takes years to setup well-structured randomized control trials and then more time to execute midterm length studies. More importantly, I do not think that robotic-assisted surgery in and of itself is what is going to be the paradigm shift in our ability to improve on TKA. I think it is the ability to passively collect structured data intraoperatively that will change our patients lives. Big improvements will come after years of these structured data being compared with individual patient profiles, as well as outcomes, and then the use of robotics to hit prescribed intraoperative goals.
As this study reports, the present state of robotic-assisted TKA is equivocal or slightly improved at best, but I do think the future is bright.
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