Two-year RSA migration results of symmetrical and asymmetrical tibial components in total knee arthroplasty: a randomized controlled trial

Bone Joint J. 2021 May;103-B(5):855-863. doi: 10.1302/0301-620X.103B5.BJJ-2020-1575.R2.


Aims: The objective of this study was to compare the two-year migration pattern and clinical outcomes of a total knee arthroplasty (TKA) with an asymmetrical tibial design (Persona PS) and a well-proven TKA with a symmetrical tibial design (NexGen LPS).

Methods: A randomized controlled radiostereometric analysis (RSA) trial was conducted including 75 cemented posterior-stabilized TKAs. Implant migration was measured with RSA. Maximum total point motion (MTPM), translations, rotations, clinical outcomes, and patient-reported outcome measures (PROMs) were assessed at one week postoperatively and at three, six, 12, and 24 months postoperatively.

Results: A linear mixed-effect model using RSA data of 31 asymmetrical and 38 symmetrical TKAs did not show a difference in mean MTPM migration pattern of the tibial or femoral components. Mean tibial component MTPM at two years postoperative of the asymmetrical TKA design was 0.93 mm and 1.00 mm for the symmetrical design. For the femoral component these values were 1.04 mm and 1.14 mm, respectively. No significant differences were observed in other migration parameters or in clinical and PROM measurements.

Conclusion: The TKA design with an asymmetrical tibial component has comparable component migration with the proven TKA with a symmetrical tibial component. This suggests the risk of long-term aseptic loosening of the two designs is comparable. Cite this article: Bone Joint J 2021;103-B(5):855-863.

Keywords: Anatomical design; Asymmetrical design; Migration; Phased introduction; Radiostereometric analysis; Total knee arthroplasty.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Arthritis, Rheumatoid / surgery
  • Female
  • Foreign-Body Migration / diagnostic imaging*
  • Humans
  • Knee Prosthesis*
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / surgery
  • Patient Reported Outcome Measures
  • Prospective Studies
  • Prosthesis Design*
  • Prosthesis Failure
  • Radiostereometric Analysis*