Abstract
Although several studies highlight the advantages of robotic arm-assisted total knee
arthroplasty (RA-TKA), few investigate its intraoperative outcome. Therefore, the
purpose of this study was to analyze the RA-TKA's ability to assist with intraoperative
correction of: (1) flexion and (2) extension gaps, as well as its ability to (3) accurately
predict implant sizes. Additionally, in this RA-TKA cohort, length of stay, complications,
and readmissions were assessed. A total of 335 patients who underwent RA-TKA were
included. The robotic software virtually measured the intraoperative prebone cut extension
and flexion gaps. Differences in medial versus lateral prebone cut extension and flexion
gaps were calculated. A total of 155 patients (46%) had an extension gap difference
of between –2 and 2 mm (mean, –0.3 mm), while 119 patients (36%) had a flexion gap
difference of between –2 and 2 mm (mean, –0.6 mm). Postbone cut differences in medial
versus lateral flexion and extension gaps were measured. Balanced knees were considered
to have a medial and lateral flexion gap difference within 2 mm. The robot-predicted
implant size was also compared with the final implant size. Additionally, lengths
of stay, complications, and readmissions were assessed. All patients achieved a postbone
cut extension gap difference between –1 and 1 mm (mean, –0.1 mm). A total of 332 patients
(99%) achieved a postbone cut flexion gap difference of between –2 and 2 mm (mean,
0 mm). For 98% of prostheses, the robotic software predicted within 1 implant size
the actual tibial or femoral implant size used.
The mean length of stay was found to be 2 days. No patients suffered from superficial
skin infection, pin site infections or fractures, soft tissue damage, and no robotic
cases were converted to manual TKA due to intraoperative complications. A total of
8 patients (2.2%) were readmitted; however, none were directly related to robotic
use. The robotic software and use of a preoperative computed tomography (CT) substantially
helped with intraoperative planning and accurate prediction of implant sizes. Therefore,
based on the results of this study, the RA-TKA device does, in fact, provide considerable
intraoperative assistance.
Keywords
total knee arthroplasty - robotic TKA - intraoperative planning - outcomes
