Does component placement affect short-term clinical outcome in robotic-arm assisted unicompartmental knee arthroplasty?

Bone Joint J. 2019 Apr;101-B(4):435-442. doi: 10.1302/0301-620X.101B4.BJJ-2018-0753.R1.


Aims: The purpose of this multicentre observational study was to investigate the association between intraoperative component positioning and soft-tissue balancing on short-term clinical outcomes in patients undergoing robotic-arm assisted unicompartmental knee arthroplasty (UKA).

Patients and methods: Between 2013 and 2016, 363 patients (395 knees) underwent robotic-arm assisted UKAs at two centres. Pre- and postoperatively, patients were administered Knee Injury and Osteoarthritis Score (KOOS) and Forgotten Joint Score-12 (FJS-12). Results were stratified as "good" and "bad" if KOOS/FJS-12 were more than or equal to 80. Intraoperative, post-implantation robotic data relative to CT-based components placement were collected and classified. Postoperative complications were recorded.

Results: Following exclusions and losses to follow-up, 334 medial robotic-arm assisted UKAs were assessed at a mean follow-up of 30.0 months (8.0 to 54.9). None of the measured parameters were associated with overall KOOS outcome. Correlations were described between specific KOOS subscales and intraoperative, post-implantation robotic data, and between FJS-12 and femoral component sagittal alignment. Three UKAs were revised, resulting in 99.0% survival at two years (95% confidence interval (CI) 97.9 to 100.0).

Conclusion: Although little correlation was found between intraoperative robotic data and overall clinical outcome, surgeons should consider information regarding 3D component placement and soft-tissue balancing to improve patient satisfaction. Reproducible and precise placement of components has been confirmed as essential for satisfactory clinical outcome. Cite this article: Bone Joint J 2019;101-B:435-442.

Keywords: Alignment; Clinical outcome; Robotic; Soft-tissue balancing; Unicompartmental knee arthroplasty.

Publication types

  • Multicenter Study
  • Observational Study

MeSH terms

  • Aged
  • Arthroplasty, Replacement, Knee / methods*
  • Equipment Design
  • Female
  • Femur / diagnostic imaging
  • Femur / surgery*
  • Follow-Up Studies
  • Humans
  • Imaging, Three-Dimensional
  • Knee Joint / diagnostic imaging
  • Knee Joint / surgery*
  • Knee Prosthesis*
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / diagnosis
  • Osteoarthritis, Knee / surgery*
  • Patient Satisfaction
  • Prospective Studies
  • Robotics / instrumentation*
  • Time Factors
  • Tomography, X-Ray Computed
  • Treatment Outcome