Robotic-arm assisted TKA may offer benefit vs non-robotic assistance
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Use of a robotic arm during total knee arthroplasty indicated clinically important differences compared to TKA performed with non-robotic arm assistance, according to results of a study with 2-year minimum follow-up presented at the Orthopaedic Research Society Annual Meeting.
Laura Scholl, MS, presented the findings of Kenneth A. Gustke, MD, who used forgotten joint scores (FJS), Knee Society Function Scores (KS–FS) and Knee Society Knee Scores (KS-KS) to compare a consecutive series of the two TKA procedures.
Balance without realignment
Gustke reviewed 2-year follow-up data of 70 robotic-arm assisted TKAs (RA-TKA) and 70 non-robotic-arm assisted TKAs (NRA-TKA) that he performed.
“Both groups had the same total knee implant. It was a Triathlon [Stryker], and there were no differences in baseline characteristics with respect to age, gender and preoperative deformity,” Scholl, who is a Stryker employee, said.
Gustke found 50% of RA-TKA cases were able to be balanced with component realignment without a soft tissue release vs. 21.4% of the NRA-TKA cases. At 2-year follow-up, 78% of RA-TKA cases had a maximum flexion angle equal to or greater than 125° compared with 34% of NRA-TKA cases.
An improvement was seen in the median KS-KS in both the RA-TKA and NRA-TKA groups from preoperatively to 2 years postoperatively (41 to 100 and 39 to 99, respectively). Also, improvements occurred in KS-FS in both the RA-TKA and NRA-TKA groups (50 to 100 and 50 to 90, respectively). Neither of these improvements represented a statistically significant difference, which may be due to the high ceiling effect of this scoring system. However, the 10-point difference for the KS-FS is a minimal clinically important difference (MCID), according to Scholl.
Forgotten joint scores analyzed
Gustke also determined FJS results were better with RA-TKA, Scholl noted. The median FJS at 2 years for the RA-TKA group was 75.0 vs. 61.5 for the NRA-TKA group. This 13.5-point difference also represented a MCID. The normative FJS value for the knee joint in the general U.S. population is 75, according to research by Johannes M. Giesinger and colleagues.
“[Gustke] also looked at it from the perspective of what percentage of patients had over an 80 [FJS] because that has been represented as an excellent clinical outcome. He found that, for his robotic group, it was 42% vs. 31% [for his non-robotic group],” Scholl said.
Scholl noted that although Gustke’s comparison data did not have statistically significant differences, the improved flexion, ability to balance the knee arthroplasties with fewer soft tissue releases, and MCIDs in KS-FS and FJS demonstrated potential benefits of robotic-arm assistance over manual instrumentation.
Reference:
Blyth MNG, et al. Bone Joint Res. 2017;doi:10.1302/2046-3758.611.BJR-2017-0060.R1.
Giesinger JM, et al. J Arthroplasty. 2019;doi:10.1016/j.arth.2018.12.011
Gustke K, et al. Paper 521. Presented at: Orthopaedic Research Society Annual Meeting; Feb. 8-11, 2020; Phoenix.
Martimbianco AL, et al. Acta Ortop Bras. 2012;doi:10.1590/S1413-78522012000100007.
For more information:
Kenneth A. Gustke, MD, can be reached at Florida Orthopaedic Institute, 13020 Telecom Parkway W., Temple Terrace, FL 33637; email: kgustke@floridaortho.com.
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