Unilateral versus bilateral total knee arthroplasty: A registry study on survival and risk factors

Bertrand Boyer, Barbara Bordini, Dalila Caputo, Thomas Neri, Susanna Stea, Aldo Toni

Research output: Contribution to journalArticlepeer-review


BACKGROUND: Bilateral cases, representing at least 25% of total knee arthroplasties (TKA), could convey a statistical bias linked to dependency. Registries allow exploring this issue, susceptible to question surgeon validated protocols. Do bilateral total knee arthroplasties behave differently than unilateral knees in terms of implant survival?

HYPOTHESIS: Bilateral TKA have a better survival than unilateral TKA.

PATIENTS AND METHODS: A number of 14,652 bilateral and 27,440 unilateral TKAs were compared. Influencing factors were tested with hazard ratios applied on bilateral knees.

RESULTS: Bilateral knees had a better survival (p<0.001). Delay between first and second side surgeries had an influence on survival of the first knee: if below a year, the first knee survival was superior to the second knee; more than three years between both arthroplasties significantly decreased the survival of the first implant. If the first knee was revised, the hazard ratio for revision of the second implant was 3.5.

DISCUSSION: Series should include separate evaluations of bilateral cases, because they have a better survival than unilateral knees. A long delay between both knee replacements could impact both implant survivals. Level of Evidence III, Cohort Comparative Study.

Original languageEnglish
Pages (from-to)627-631
Number of pages5
JournalOrthopaedics and Traumatology: Surgery and Research
Issue number4
Early online dateApr 23 2019
Publication statusPublished - Jun 2019


  • Bilateral vs unilateral
  • Registry
  • Survival
  • Total knee arthroplasty


Dive into the research topics of 'Unilateral versus bilateral total knee arthroplasty: A registry study on survival and risk factors'. Together they form a unique fingerprint.

Cite this