December 16, 2019
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Robotic-assisted UKA yielded excellent survivorship at 5 years

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Matthew Banger

Patients who underwent unicompartmental knee arthroplasty undertaken with robotic assistance experienced excellent mid-term survivorship compared with patients whose surgery was performed manually, according to results presented at a meeting.

“Generally, what has been shown in the other literature, as well as in this study, is that procedures using the robotic system have lower revision rates. A better overall survivorship is a result of both the procedure and the implant,” Matthew Banger, EngD, co-author of the study which won the EFORT Gold Orthopaedics Abstract Award, told Orthopedics Today. “This is indicating that the technology is having an impact not only on early pain scores, but also in mid-term survivorship.”

Manual vs. robotic

Banger and his colleagues randomly assigned 139 patients undergoing unicompartmental knee arthroplasty (UKA) to receive either the Oxford manual implant (Zimmer Biomet) or the Mako Restoris robotically assisted implant (Stryker). Researchers assessed outcomes using the American Knee Society Score, Oxford Knee Score, VAS for pain and stiffness, Forgotten Joint Score, complications and adverse events.

“The primary outcome of the study was looking at the implant accuracy with secondary outcomes looking at gait, functional ability and other clinical outcomes,” Banger said in his presentation.

At 5 years, patients had a rate of retention of 80% with no significant differences between the two groups. Survivorship analysis showed the robotic-assisted group had no reported revisions compared with a 3% revision rate in the manual group, Banger said.

“This was not shown to be significant between the two, but when reviewing reintervention, the requirement to have any kind of additional surgery was shown to actually be statistically significant between the two,” which was in favor of the robotic-assisted group, Banger said.

The manual group also had a significant increase in the rate of radiolucent lines compared with the robotic group, he said, noting this indicates some physiological difference in the underlying bone.

“We are going to follow [these patients] up to 10 years [to see] if there is a similar survivorship. We have already seen that there have been additional revisions after 5 years in the manual group,” Banger told Orthopedics Today. “Unfortunately, we are still seeing failures in the manual system, but … it has come with 97% survivorship, which is still good, but the robotic system is showing better mid-term survivorship.”

These study data are currently under review for publication, he noted.

Robotics in difficult surgeries

Banger and colleagues are also performing MHRA-approved off-label trials to determine whether robotic assisted surgery can be beneficial in surgeries that can be difficult to perform manually. They are looking at the outcomes of performing two UKAs in the same knee compared with total knee replacement, Banger said.

“The robotic system could potentially assist on more technically challenging procedures to enable them to become more routine as we have seen relatively good outcomes are part of this initial trial,” he said. – by Casey Tingle

Reference:

Banger MS, et al. Abstract 2461. Presented at: EFORT Annual Congress; June 5-7, 2019; Lisbon, Portugal.

For more information:

Matthew S. Banger, EngD, can be reached at University of Strathclyde, The Technology and Innovation Centre, 99 George St., Glasgow, G1 1RD, United Kingdom; email: matthew.banger@strath.ac.uk.

Disclosure: Banger reports the investigators received an institutional support grant from the Mako Surgical Corporation.