Mid-term migration of the Triathlon versus Duracon total knee systems
A randomized RSA study concentrating especially on continuous migrationActa Orthop. 2016 Jun;87(3):262-7
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60 patients with knee osteoarthritis and scheduled for total knee arthroplasty were randomized to receive either a newer-generation Triathlon total knee system, or older-generation Duracon total knee system. The purpose of this study was to compare tibial component stability between groups at short- and mid-term follow-up. Three-dimensional translation and rotation of the component were assessed using radiostereometric analysis. After 5 years, significant difference between groups was only observed in varus-valgus rotation.
Was the allocation sequence adequately generated?
Was allocation adequately concealed?
Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?
Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?
Blinding Patients: Was knowledge of the allocated interventions adequately prevented?
Was loss to follow-up (missing outcome data) infrequent?
Are reports of the study free of suggestion of selective outcome reporting?
Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?
Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?
Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?
Yes = 1
Uncertain = 0.5
Not Relevant = 0
No = 0
The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.
Inclusion / Exclusion
Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65
The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.
Why was this study needed now?
The evolution of prostheses for total knee arthroplasty is continuously ongoing. Newer-generation implants are typically released and phased into clinical practice, ultimately replacing routine use of earlier-generation implants over many years. Within this process, careful consideration of long-term outcome of new implants is crucial to ensure patients are not experiencing worse stability and survivorship compared to older implants with proven track records.
What was the principal research question?
In total knee arthroplasty, was there any significant difference in radiostereometrically-assessed micromotion of the tibial component between the Triathlon and Duracon cemented knee systems over 5-year follow-up?
What were the important findings?
- No significant differences between the Duracon and Triathlon groups were observed after 5 years in medial-lateral translation (-0.34+/-1.26 vs. -0.33+/-0.46mm; p=1.0), caudal-cranial translation (-0.5+/-0.51 vs. 0.1+/-0.27mm; p=0.2), or posterior-anterior translation (-0.33+/-1.22 vs. 0.18+/-0.59; p=0.1).
- Overall, mean MTPM after 5 years did not significantly differ between the Duracon group (1.10+/-1.21) and the Triathlon group (0.66+/-0.38)
- No significant differences between the Duracon and Triathlon groups were observed after 5 years in anterior-posterior tilt (0.10+/-0.38 vs. -0.9+/-0.31deg; p=0.1) or internal-external rotation (-0.19+/-0.64 vs. -0.09+/-0.31deg; p=0.5). A significant difference was observed between groups in varus-valgus rotation of the component after 5 years, with 0.18deg (+/-0.48) varus rotation in the Duracon group versus 0.09deg (+/-0.28) valgus rotation in the Triathlon group.
- Continuous migration of the tibial component between years 1 and 2 was observed in 7/24 patients of the Duracon group and 5/26 patients of the Triathlon group.
- Continuous migration of the tibial component between years 2 and 5 was observed in 6/21 patients of the Duracon group and 3/21 patients of the Triathlon group (p=0.2).
What should I remember most?
In total knee arthroplasty, 5-year maximum total point motion of the tibial component did not significantly differ between patients treated with a Triathlon or Duracon prosthesis. A similar number of patients between groups throughout follow-up demonstrated MTPM values exceeding the thresholds set by the current study as indicative of continuous migration.
How will this affect the care of my patients?
The results of this study suggest that the newer-generation Triathlon total knee system has a similar mid-term migration profile to that of the predecessor-generation Duracon total knee system. Continued follow-up is necessary to determine if the migration profiles of these two systems remain similar into the long-term.
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