Aims We developed a novel unicompartmental pressure sensor to measure intraoperative medial compartment pressureduring robotic arm-assisted unicompartmental knee arthroplasty (UKA) and conventional jig-based UKA in order to assess the effect and impact of soft-tissue balance. Methods This retrospective study evaluated 80 patients who underwent medial compartment UKA at our institution between November 2022 and June 2023, including 40 patients in conventional jig-based (mobile bearing) UKA and 40 patients in robotic arm-assisted (fixed bearing) UKA. After intraoperative soft-tissue balancing, the medial compartment pressure at 10°, 45°, and 90° of knee flexion was measured using a new unicompartmental pressure sensor. The knee range of motion (ROM), Numerical Rating Scale, and American Knee Society scores were recorded at three months and one year of follow-up. Results Conventional jig-based UKA did not achieve consistent medial compartment pressures at 10°, 45°, and 90° of knee flexion (p 0.999, respectively). In addition, robotic arm-assisted UKA showed better outcome scores and ROM at three months, but no significant clinical differences at the one-year follow-up. Conclusion Intraoperative pressure measurements using the novel unicompartmental pressure sensor showed that robotic arm-assisted UKA was able to achieve more consistent pressure in the medial compartment than conventional jig-based UKA, which may improve early postoperative rehabilitation. Cite this article: Bone Joint J 2026;108-B(3):302–309.
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