Higher medial-to-lateral sBMD tied to OA knee pain presence, progression

A higher ratio of medial-to-lateral subchondral bone mineral density (sBMD) appears predictive of the presence and progression of knee pain in people with osteoarthritis (OA), suggests a study.

Some 594 participants (mean age 64.1 years, 50.5 percent male) were included in the analysis. Of the 1,137 knees assessed, 31.6 percent presented with higher pain at baseline, and 37.4 percent had pain progression during follow-up.

Higher medial sBMD (odds ratio [OR], 1.50, 95 percent confidence interval [CI], 1.25‒1.81; p<0.001) and medial-to-lateral sBMD ratio (OR, 1.29, 95 percent CI, 1.11‒1.49; p=0.001) significantly correlated with the progression of knee pain.

The medial-to-lateral sBMD ratio also showed a significant association with the presence of knee pain (OR, 1.21, 95 percent CI, 1.05‒1.40; p=0.01).

These findings suggest “that relative subchondral bone distribution may better capture biomechanical loading imbalance related to symptomatic OA than absolute sBMD alone,” the investigators said.

This study recruited participants from the Osteoarthritis Initiative. The investigators measured tibial sBMD at medial and lateral compartments using dual-energy x-ray absorptiometry at 30 or 36 months (baseline), with reassessment at 48 months. They assessed knee pain using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain subscale through month 108.

Baseline knee pain was characterized as low/no or high (pain score <5 vs ≥5). Pain progression was defined as an increase in WOMAC pain score of ≥2 in at least three of the six follow-up visits.

Finally, the investigators explored the relationship between sBMD and knee pain using logistic regression with generalized estimating equations, accounting for within-participant correlation between knees.