Secondary patellar resurfacing helps most when done more than 2.5 years after the primary knee

Design

Retrospective single-centre arthroplasty register study

Population

182 patients undergoing secondary patellar resurfacing after TKA

Primary outcome

Oxford Knee Score, EQ-5D and satisfaction at 1 and 2 years

Effect

OKS +6.8 (4.7 to 8.9) at 1 year, +8.1 at 2 years; 85.7% satisfied at 2 years

This UK single-centre register study, published 1 September in the Bone & Joint Journal, followed 182 patients who had secondary patellar resurfacing after a primary knee replacement without resurfacing, between 2006 and 2022.

Oxford Knee Score improved by 6.8 points at one year and 8.1 at two years, and EQ-5D by about 0.17–0.19. Satisfaction was 79.7% at one year and 85.7% at two. Patients satisfied with their original knee were far more likely to be satisfied after resurfacing (OR 10.4), and each extra year between the primary and the resurfacing raised the odds of satisfaction. A 2.5-year interval was the best cut-off. No re-revisions were needed over a median of ten years.

For anterior knee pain after an unresurfaced knee, this gives surgeons a realistic expectation: a moderate improvement for most, and better odds when the knee was once good and some time has passed.

• Expect a moderate gain in Oxford Knee Score (about 7–8 points) after secondary patellar resurfacing.
• Patients who were happy with their original knee are much more likely to benefit.
• Outcomes were better when resurfacing was done more than 2.5 years after the primary.
• Exclude other causes of pain, such as component malrotation or infection, before offering it.

Why it matters

Helps separate the patient likely to benefit from the one whose dissatisfaction has another cause.

Don't overread it

Single-centre retrospective data with no comparison group.

The statistics, in plain English

The odds ratio of 10.4 for prior satisfaction has a very wide confidence interval (3.1 to 34.9), so the direction is clear but the exact size is not.

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