Robotic arm-assisted UKA improves tibial component alignment: a pilot study.
The alignment of the components of unicompartmental knee arthroplasty (UKA) reportedly influences outcomes and durability. A novel robotic arm technology has been developed with the expectation that it could improve the accuracy of bone preparation in UKA. During the study period, we compared the postoperative radiographic alignment of the tibial component with the preoperatively planned position in 31 knees in 31 consecutive patients undergoing UKA using robotic arm-assisted bone preparation and in 27 consecutive patients who underwent unilateral UKA using conventional manual instrumentation to determine the error of bone preparation and variance with each technique. Radiographically, the root mean square error of the posterior tibial slope was 3.1 degrees when using manual techniques compared with 1.9 degrees when using robotic arm assistance for bone preparation. In addition, the variance using manual instruments was 2.6 times greater than the robotically guided procedures. In the coronal plane, the average error was 2.7 degrees +/- 2.1 degrees more varus of the tibial component relative to the mechanical axis of the tibia using manual instruments compared with 0.2 degrees +/- 1.8 degrees with robotic technology, and the varus/valgus root mean square error was 3.4 degrees manually compared with 1.8 degrees robotically. Further study will be necessary to determine whether a reduction in alignment errors of these magnitudes will ultimately influence implant function or survival.


METHODS
Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
Lonner
Jess H
JH
Booth Bartolozzi Balderston Orthopaedics, Pennsylvania Hospital, 800 Spruce Street, Philadelphia, PA 19107, USA. lonnerj@pahosp.com
John
Thomas K
TK
Conditt
Michael A
MA
D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D010865:Pilot Projects; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies; D011859:Radiography; D012371:Robotics; D025321:Surgery, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D013977:Tibia / Q000000981:diagnostic imaging / Q000601:surgery*