Primary total knee arthroplasty in patients under 55 years of age: is the mid-term revision rate worrying?

Introduction: The indications for total knee arthroplasty (TKA) are expanding to include younger and more active patients. Several recent studies have warned of a higher revision rate and lower patient satisfaction in younger patients. The aim of this study was to assess the survival of TKAs in patients under the age of 55 and to determine the risk factors for revision and complications.

Hypothesis: The hypothesis was that TKA survival in patients under 55 years of age is greater than 90% at 10 years.

Materials and methods: This work was a single-center retrospective study. All patients under 55 years of age with first-line TKA between 2006 and 2016 were included. The survival rate was calculated with TKA failure as the primary outcome, which was defined as revision surgery regardless of cause. The Kaplan‒Meier method was used to meet the primary objective.

Results: A total of 168 patients (median age 52 years) with 193 TKAs were included. The mean follow-up was 7.9 years, and 24 cases of failure were identified. The 10-year survival rate was 86.6% (95% CI [81.1-92.2]). The mean time to failure was 4.1 years. Mechanical loosening and infection were the main causes of failure. Body mass index (BMI) appeared to increase the risk of revision (p < 0.01). TKAs with a third condyle were less strongly associated with the risk of revision and complications (p < 0.05), as was the presence of a tibial keel (p < 0.05). TKAs with posttraumatic gonarthrosis (p = 0.066), osteonecrosis (p < 0.05) and sequelae of septic arthritis (p < 0.05) appeared to be the most at risk of revision.

Conclusion: This hypothesis has not been verified, and TKA in patients under 55 years of age appears to have a higher revision rate than in the general population. The indication for TKA in these patients remains a reliable option, but certain risk factors must be considered.

Level of evidence: IV; retrospective study.