PTCohortJournal of rehabilitation medicine2026

Relative fat mass predicts symptomatic knee osteoarthritis in older adults with metabolic syndrome: a longitudinal cohort study.

Lei Huang, Yuhui Wang, Yuhao Chen and 8 others

PMID 42693778

WHAT IT FOUND

In Chinese adults with metabolic syndrome, higher relative fat mass was associated with new symptomatic knee osteoarthritis during follow-up.

It identified risk better than BMI, but the paper describes the gain as modest and meant for screening, not diagnosis.

Key findings

01Among 3,301 participants with metabolic syndrome, new symptomatic knee osteoarthritis was reported in 21% of the lowest relative fat mass quartile and 37% of the highest quartile.

02In the fully adjusted model, the hazard ratio for new symptomatic knee osteoarthritis was 1.50 for the highest relative fat mass quartile compared with the lowest quartile.

03In screening accuracy analysis, relative fat mass had an area under the curve of 0.587 for new symptomatic knee osteoarthritis, compared with 0.532 for BMI.

STILL TO COME

How it was doneWhat they foundWhat it means for PTs

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What it does not show

The study is observational, and the authors noted residual confounding, so it cannot show that relative fat mass changes knee osteoarthritis risk. Symptomatic knee osteoarthritis was defined from self-reported physician diagnosis and pain location, and the authors noted potential measurement error. Only 3,301 of the 17,705 baseline participants remained after exclusions for missing data or absence of metabolic syndrome. The authors noted lack of longitudinal relative fat mass data and limited generalizability beyond Chinese older adults with metabolic syndrome. The rural versus urban interaction had borderline significance, and the authors said it should be interpreted with caution.

Declared interests

The authors declared no conflicts of interest. The research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

The easy way to misread this

Do not use relative fat mass to diagnose knee osteoarthritis in an individual patient. The paper describes the advantage over BMI as modest and says it should not be overinterpreted for individual-level diagnosis.

Read it on PubMed →