Comparable clinical outcome and implant longevity after CT- or MRI-based patient-specific instruments for total knee arthroplasty: a 2-year follow-up of a RCT

Elke Thijs, Dieuwertje Theeuwen, Bert Boonen, Emil van Haaren, Roel Hendrickx, Rein Vos, Rob Borghans, Nanne Kort, Martijn G M Schotanus*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


PURPOSE: Patient-specific instruments (PSI) are already widespread used in total knee arthroplasty (TKA). Either computed tomography (CT) scans or magnetic resonance imaging (MRI) scans are used pre-operatively to create jigs to guide resection during surgery. This study is a sequel of previous work that showed significantly more radiological outliers for posterior slope when CT-based guides were used. The aim of this study was to assess differences in revision rate and clinical outcome between the two groups at 2-year follow-up.

METHODS: At the 2-year follow-up, 124 patients were analysed in this prospective, randomised single-blind study. A survival analysis with revision of the TKA as endpoint was performed. Patients fulfilled four patient-reported outcome measurements (PROMs). Scores on the questionnaires were compared between both groups at the different follow-up visits.

RESULTS: At final follow-up, there was no significant difference in the survival rates of the CT- and MRI-based PSI surgery. Postoperatively, the PROMs significantly improved within each group compared with the pre-operative values. There were no significant differences for the PROMs between both groups at the 2-years follow-up.

CONCLUSIONS: Although previous results showed more outliers regarding posterior slope for CT-based PSIs, no difference in revision rate or the outcome of PROMs was found at 2-year follow-up. Further research to determine what the influence is of radiological outliers on implant survival and clinical outcomes is necessary.


Original languageEnglish
Pages (from-to)1821-1826
Number of pages6
JournalKnee Surgery Sports Traumatology Arthroscopy
Issue number6
Early online date3 Jul 2019
Publication statusPublished - Jun 2020


  • Patients-specific instruments
  • Total knee arthroplasty
  • Total knee replacement
  • Magnetic resonance imaging
  • Computed tomography
  • Clinical outcome
  • Survival
  • Revision rate
  • MRI
  • CT
  • PSI
  • TKA
  • AXIS

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