Improved Accuracy of Component Positioning with Robotic-Assisted Unicompartmental Knee Arthroplasty: Data from a Prospective, Randomized Controlled Study.
BACKGROUND
Higher revision rates have been reported in patients who have undergone unicompartmental knee arthroplasty compared with patients who have undergone total knee arthroplasty, with poor component positioning identified as a factor in implant failure. A robotic-assisted surgical procedure has been proposed as a method of improving the accuracy of component implantation in arthroplasty. The aim of this prospective, randomized, single-blinded, controlled trial was to evaluate the accuracy of component positioning in unicompartmental knee arthroplasty comparing robotic-assisted and conventional implantation techniques.


METHODS
One hundred and thirty-nine patients were randomly assigned to treatment with either a robotic-assisted surgical procedure using the MAKO Robotic Interactive Orthopaedic Arm (RIO) system or a conventional surgical procedure using the Oxford Phase-3 unicompartmental knee replacement with traditional instrumentation. A postoperative computed tomographic scan was performed at three months to assess the accuracy of the axial, coronal, and sagittal component positioning.


RESULTS
Data were available for 120 patients, sixty-two who had undergone robotic-assisted unicompartmental knee arthroplasty and fifty-eight who had undergone conventional unicompartmental knee arthroplasty. Intraobserver agreement was good for all measured component parameters. The accuracy of component positioning was improved with the use of the robotic-assisted surgical procedure, with lower root mean square errors and significantly lower median errors in all component parameters (p < 0.01). The proportion of patients with component implantation within 2° of the target position was significantly greater in the group who underwent robotic-assisted unicompartmental knee arthroplasty compared with the group who underwent conventional unicompartmental knee arthroscopy with regard to the femoral component sagittal position (57% compared with 26%, p = 0.0008), femoral component coronal position (70% compared with 28%, p = 0.0001), femoral component axial position (53% compared with 31%, p = 0.0163), tibial component sagittal position (80% compared with 22%, p = 0.0001), and tibial component axial position (48% compared with 19%, p = 0.0009).


CONCLUSIONS
Robotic-assisted surgical procedures with the use of the MAKO RIO lead to improved accuracy of implant positioning compared with conventional unicompartmental knee arthroplasty surgical techniques.


METHODS
Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
Department of Orthopaedics, Glasgow Royal Infirmary, Glasgow, United Kingdom drstuartbell@gmail.com.
Stuart W
SW
Bell
Department of Orthopaedics, Glasgow Royal Infirmary, Glasgow, United Kingdom.
Iain
I
Anthony
Department of Orthopaedics, Glasgow Royal Infirmary, Glasgow, United Kingdom.
Bryn
B
Jones
Department of Orthopaedics, Glasgow Royal Infirmary, Glasgow, United Kingdom.
Angus
A
MacLean
Department of Orthopaedics, Glasgow Royal Infirmary, Glasgow, United Kingdom Biomedical Engineering Department, University of Strathclyde, Glasgow, United Kingdom.
Philip
P
Rowe
Department of Orthopaedics, Glasgow Royal Infirmary, Glasgow, United Kingdom.
Mark
M
Blyth
D019645:Arthroplasty, Replacement, Knee / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D058996:Quality Improvement; D065287:Robotic Surgical Procedures; D016037:Single-Blind Method