Reviewed by Madison Hof, SPT
Introduction
Though conventional Total Knee Arthroplasty (TKA) procedures have yielding good long-term results in the past, robotic-assisted TKA was introduced to improve implantation alignments, particularly in younger patients. These alignment improvements were studied in this randomized controlled trial to determine if robotic-assisted TKA results demonstrate improved long-term outcome scores or implant survivorship. A large randomized, controlled trial was conducted using patients who received either robotic-assisted or conventional TKA procedures and have reached long-term (10-year minimum) follow-ups to determine if robotic-assisted TKA is superior. Terms for determination include (1) functional results based on Knee Society, WOMAC and UCLA Activity scores, (2) radiographic parameters, (3) Kaplan-Meier survivorship, and (4) complications specific to robotic-assistance, including pin tract infection, peroneal nerve palsy, pin-site fracture, or patellar complications.
Patients and Methods
1406 eligible patients were selected from one performing surgeon with surgery dates ranging from January 2002 to February 2008. 700 patients (750 knees) received robotic-assisted TKA and 706 patients (766 knees) received conventional TKA. 674 patients from the robotic-assisted TKA group and 674 patients from the conventional TKA group were available to be evaluated for clinical, radiographic, and CT scans at follow-up at an average of 13 (+/-5) years post-op. The robotic assisted TKA group consisted of 542 women and 132 men with an age range between 49 to 65 years old. The conventional TKA group consisted of 530 women and 144 men with an age range between 46 to 65 years old.
Patients from both groups were ambulatory using either crutches or a walker on the second postoperative day and were all discharged to home. Medical advice was given to all to use their assisted devices for 4 to 6 weeks and a cane thereafter as needed to prevent falls. Postoperative follow-up examinations were performed at 3 months, 1 year, and every 2 to 3 years thereafter.
Results
Functional Outcomes
It was found that there was no difference in clinical outcome measure at the most recent follow-up for those who received robotic-assisted TKAs compared to those who received conventional TKAs. Mean total Knee Society knee scores, residual pain levels, WOMAC scores, ROM, and mean UCLA activity scores showed no difference in outcomes.
Radiographic Outcomes
According to radiographic parameters measures, including limb alignment, component alignment, and aseptic loosening, there was no difference in outcomes found between groups. The rotational alignment of the femoral component from the transepicondylar axis or tibial component also showed no difference.
Component Survivorship
Both groups showed the same percentage of implant survivorship (98%) at 15 years after the operation.
Complications
The frequency of complications yielded no difference between groups. Four knees in each group acquired a superficial infection and were treated with intravenous antibiotics for 2 weeks. There were no reports of deep infection, pin site fracture, pin tract infection, patellar dislocation, patellar fracture, supracondylar fracture or peroneal nerve palsy in either group.
Discussion
It was found in this randomized controlled trial that there was no difference in outcome scores, mean implant or limb alignment, survivorship, or complications between individuals who received a robotic-assisted TKA versus individuals who received a conventional TKA at an average 10 year follow up. However, a small reduction in the proportion of knees aligned more than 3 degrees away from neutral using robotic-assisted methods was found. Meaning, there were less knees in robotic-assisted TKA that were misaligned from neutral more than 3 degrees. This demonstrates that the overall knee positioning in robotic-assisted TKA achieved more precise neutral mechanical axis alignment than conventional TKA.
Limitations of the study include having no morbidly obese patients evaluated, which is a group who may benefit more from robotic assisted procedures given the difficulties associated with identifying landmarks with a conventional TKA procedure. This study also included a population of predominantly women with low body weight and good preoperative ROM which these factors could limit the applicability of this study to other patients.
Reference
Kin YH, Yoon SH, Park JW. Does Robotic-assisted TKA Result in Better Outcome Scores or Long-Term Survivorship Than Conventional TKA? A Randomized, Controlled Trial. Clinical Orthopaedics and Related Research. 2020;478(2):266-275. Doi:https://doi.org/10.1097/corr.0000000000000916