Reduction in patient outcomes but implant-derived preservation of function following total knee arthroplasty: longitudinal follow-up of a randomized controlled trial

David F. Hamilton*, Richard Burnett, James T. Patton, Gavin J. MacPherson, A. H.R.W. Simpson, Colin R. Howie, Paul Gaston

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
1 Downloads (Pure)


AIMS: There are comparatively few randomized studies evaluating knee arthroplasty prostheses, and fewer still that report longer-term functional outcomes. The aim of this study was to evaluate mid-term outcomes of an existing implant trial cohort to document changing patient function over time following total knee arthroplasty using longitudinal analytical techniques and to determine whether implant design chosen at time of surgery influenced these outcomes.

METHODS: A mid-term follow-up of the remaining 125 patients from a randomized cohort of total knee arthroplasty patients (initially comprising 212 recruited patients), comparing modern (Triathlon) and traditional (Kinemax) prostheses was undertaken. Functional outcomes were assessed with the Oxford Knee Score (OKS), knee range of movement, pain numerical rating scales, lower limb power output, timed functional assessment battery, and satisfaction survey. Data were linked to earlier assessment timepoints, and analyzed by repeated measures analysis of variance (ANOVA) mixed models, incorporating longitudinal change over all assessment timepoints.

RESULTS: The mean follow-up of the 125 patients was 8.12 years (7.3 to 9.4). There was a reduction in all assessment parameters relative to earlier assessments. Longitudinal models highlight changes over time in all parameters and demonstrate large effect sizes. Significant between-group differences were seen in measures of knee flexion (medium-effect size), lower limb power output (large-effect size), and report of worst daily pain experienced (large-effect size) favouring the Triathlon group. No longitudinal between-group differences were observed in mean OKS, average daily pain report, or timed performance test. Satisfaction with outcome in surviving patients at eight years was 90.5% (57/63) in the Triathlon group and 82.8% (48/58) in the Kinemax group, with no statistical difference between groups (p = 0.321).

CONCLUSION: At a mean 8.12 years, this mid-term follow-up of a randomized controlled trial cohort highlights a general reduction in measures of patient function with patient age and follow-up duration, and a comparative preservation of function based on implant received at time of surgery. Cite this article: Bone Joint J 2020;102-B(4):434-441.

Original languageEnglish
Pages (from-to)434-441
Number of pages8
JournalBone and Joint Journal
Volume102 B
Issue number4
Early online date31 Mar 2020
Publication statusPublished - 1 Apr 2020


  • aged
  • aged, 80 and over
  • arthroplasty, replacement, knee/instrumentation
  • double-blind method
  • female
  • follow-up studies
  • humans
  • knee joint/physiopathology
  • knee prosthesis
  • lower extremity/physiopathology
  • male
  • middle aged
  • osteoarthritis, knee/physiopathology
  • pain, postoperative/etiology
  • patient satisfaction
  • postoperative period
  • prosthesis design
  • prosthesis failure/etiology
  • range of motion, articular
  • reoperation/statistics & numerical data
  • severity of Illness index

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine


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