Predictive gap-balancing reduces the extent of soft-tissue adjustment required after bony resection in robot-assisted total knee arthroplasty: a comparison with simulated measured resection

Alexander D. Orsi*, Edgar A. Wakelin, Christopher Plaskos, Sanjeev Gupta, James A. Sullivan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
46 Downloads (Pure)

Abstract

Background: To understand the extent and frequency of soft-tissue adjustment required to achieve mediolateral (ML) balance in measured resection (MR) vs gap-balancing (GB) total knee arthroplasty, this study compared ML balance and joint laxity throughout flexion between the 2 techniques. The precision of predictive GB in achieving ML balance and laxity was also assessed. Methods: Two surgeons performed 95 robot-assisted GB total knee arthroplasties with predictive balancing, limiting tibial varus to 3° and adjusting femoral positioning to optimize balance. A robotic ligament tensioner measured joint laxity. Planned MR (pMR) was simulated by applying neutral tibial and femoral coronal resections and 3° of external femoral rotation. ML balance, laxity, component alignment, and resection depths were compared between planned GB (pGB) and pMR. ML balance and laxity were compared between pGB and final GB (fGB). Results: The proportion of knees with >2 mm of ML imbalance in flexion or extension ranged from 3% to 18% for pGB vs 50% to 53% for pMR (P <.001). Rates of ML imbalance >3 mm ranged from 0% to 9% for pGB and 30% to 38% for MR (P <.001). The mean pMR laxity was 1.9 mm tighter medially and 1.1 mm tighter laterally than pGB throughout flexion. The mean fGB laxity was greater than the mean pGB laxity by 0.5 mm medially and 1.2 mm laterally (P <.001). Conclusion: MR led to tighter joints than GB, with ML gap imbalances >3 mm in 30% of knees. GB planning improved ML balance throughout flexion but increased femoral posterior rotation variability and bone resection compared to MR. fGB laxity was likely not clinically significantly different than pGB.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalArthroplasty Today
Volume16
DOIs
Publication statusPublished - Aug 2022

Bibliographical note

Copyright the Publisher 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Computer-assisted
  • Gap balancing
  • Laxity
  • Measured resection
  • Robotic-assisted
  • Total knee arthroplasty

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