Total Knee Arthroplasty (TKA): when do the risks of TKA overcome the benefits?

The upshot

If I am under 65, is a total knee replacement more likely to fail than it would be in an older person?

In this large national registry analysis, total knee replacements done for osteoarthritis in people under 65 failed about twice as often over the long term as those done in older patients, with the youngest patients faring worst. The operation still works, but younger people should weigh the higher long-term revision risk.

DescriptiveRead paper

Primary study45,488 ParticipantsModerate evidence

Key points

Among 45,488 knee replacements, 15-year survival was 78.7% under age 50, 89.4% at age 50-65, and 94.8% at age 66-79.
Compared with the 66-79 group, the risk of failure was 3.1 times higher under 50 and 1.8 times higher at 50-65.
The share of knee replacements done in people under 65 nearly doubled over 2000-2019, from 13.5% to 24.8%.
Aseptic loosening (the implant loosening without infection) was the leading reason for revision in every age group.
The authors suggest joint-preserving options may delay surgery in selected younger patients.

How it was conducted

Design: Analysis of the Italian Regional Register of Orthopaedic Prosthetic Implants (RIPO), 63 hospitals in Emilia-Romagna, 2000-2019, with about 98% capture
Participants: 45,488 primary total knee replacements for primary osteoarthritis in patients under 80 (11,388 men, 27,846 women)
Groups: Three age groups: under 50, 50-65, and 66-79 years
Primary outcome: Implant revision (insert, femoral, or tibial component), analyzed with Kaplan-Meier survival, log-rank test, and Cox regression

What they found

15-year implant survival: 78.7% (95% CI 66.6-87.2) under 50, 89.4% (95% CI 88.2-90.4) at 50-65, and 94.8% (95% CI 94.5-95.2) at 66-79.
10-year survival: 86.2% (95% CI 80.6-90.4) under 50, 92.1% (95% CI 91.4-92.8) at 50-65, 95.7% (95% CI 95.4-95.9) at 66-79.
Relative risk of failure versus the 66-79 group was 3.1 (95% CI 2.2-4.3) for under 50 and 1.8 (95% CI 1.6-2.0) for 50-65.
Failure rates: 35/349 (10.0%) under 50, 569/9342 (6.1%) at 50-65, and 1231/35797 (3.4%) at 66-79.
Age significantly influenced revision rate (P < 0.0001); the share of patients under 65 rose from 13.5% to 24.8% over 2000-2019 (P < 0.0001).
Aseptic loosening was the leading revision cause (48.6%, 40.6%, 39.9% across age groups), with septic loosening second (14.3%, 21.4%, 24.8%).

Limitations

No clinical or function scores were recorded, so dissatisfied patients who did not undergo revision were not captured.
Revision was the only failure endpoint, which may understate the true rate of poor outcomes.
Data come from a single Italian region, which may limit how well results apply elsewhere.
As registry data, the analysis cannot prove that age itself causes the higher failure risk.

Why it matters

For patients: If you are under 65 and considering a knee replacement, be aware the implant is more likely to need a redo over your lifetime, so discuss timing and alternatives with your surgeon.
For clinicians: Counsel younger osteoarthritis patients on the roughly two-fold higher long-term revision risk and consider joint-preserving options before proceeding to total knee replacement.
For readers: A large registry shows that the rising use of knee replacement in middle-aged adults carries a meaningfully higher long-term revision burden than in older patients.

Source

doi:10.1177/19476035231164733

Read the original paper

Clinically assessing this area? See the knee special tests.