# Associations between hyperuricemia and ultrasound-detected knee synovial abnormalities in middle-aged and older population: a cross-sectional study

## TL;DR

This study finds a link between high uric acid levels and knee synovial issues in older adults, suggesting a possible role in their development.

## Contribution

The study is the first to show a dose-response relationship between serum urate levels and ultrasound-detected knee synovial abnormalities in a general population.

## Key findings

- Hyperuricemia is associated with increased prevalence of knee synovial abnormalities, hypertrophy, and effusion.
- Higher serum urate levels correlate with greater likelihood of bilateral synovial abnormalities.
- No significant association was found between hyperuricemia and Power Doppler signal in synovium.

## Abstract

Knee synovial abnormalities, potentially treatment targets for knee pain and osteoarthritis, are common in middle-aged and older population, but its etiology remains unclear. We examined the associations between hyperuricemia and knee synovial abnormalities detected by ultrasound in a general population sample.

Participants aged ≥ 50 years were from a community-based observational study. Hyperuricemia was defined as serum urate (SU) level > 416 µmol/L in men and > 357 µmol/L in women. Ultrasound of both knees was performed to determine the presence of synovial abnormalities, i.e., synovial hypertrophy, effusion, or Power Doppler signal (PDS). We examined the relation of hyperuricemia to prevalence of knee synovial abnormalities and its laterality, and the dose-response relationships between SU levels and the prevalence of knee synovial abnormalities.

In total, 3,405 participants were included in the analysis. Hyperuricemia was associated with higher prevalence of knee synovial abnormality (adjusted odds ratio [aOR] = 1.21, 95% confidence interval [CI]: 1.02 to 1.43), synovial hypertrophy (aOR = 1.33, 95% CI: 1.05 to 1.68), and effusion (aOR = 1.21, 95% CI: 1.02 to 1.44), respectively. There were dose-response relationships between SU levels and synovial abnormalities. Additionally, the hyperuricemia was more associated with prevalence of bilateral than with that of unilateral knee synovial abnormality, synovial hypertrophy, or effusion; however, no significant association was observed between hyperuricemia and PDS.

In this population-based study we found that hyperuricemia was associated with higher prevalence of knee synovial abnormality, synovial hypertrophy and effusion, suggesting that hyperuricemia may play a role in pathogenesis of knee synovial abnormalities.

The online version contains supplementary material available at 10.1186/s13018-024-04708-w.