Missing Link Between Inflammation and Joint Surgery?

A new multicenter research study has attempted to find or disprove that a link exists between inflammation, osteoarthritis and total joint surgery. Interestingly, they could not find it.

The study, “Prospective associations of C-reactive protein (CRP) levels and CRP genetic risk scores with risk of total knee and hip replacement for osteoarthritis in a diverse cohort,” appears in the August 2018 edition of Osteoarthritis and Cartilage.

A co-author on the work, Aladdin H. Shadyab, Ph.D., with the division of epidemiology at the University of San Diego School of Medicine told OTW, “Although osteoarthritis is usually considered a non-inflammatory condition, several studies have suggested that local and systemic inflammation might be involved in osteoarthritis; however, findings have been mixed.”

“Therefore, we conducted this study to examine the relationship between C-reactive protein, a marker of systemic inflammation, and severe knee or hip osteoarthritis as indicated by total knee or hip replacement, respectively.”

The authors first collected Hs[high sensitivity]-CRP and genotyping data from study participants to establish a baseline. They then constructed three CRP GRS [genetic risk scores]:

1. a 4-SNP GRS comprised of genetic variants representing variation in the CRP gene among European populations;
2. a multilocus 18-SNP GRS of genetic variants significantly associated with CRP levels in a meta-analysis of genome-wide association studies;
3. a 5-SNP GRS of genetic variants significantly associated with CRP levels among African American women.

The authors found, as Dr. Shadyab described to OTW, “Among white, African-American, and Hispanic women from a large, national study of postmenopausal women called the Women's Health Initiative, we observed that C-reactive protein levels in the blood and a score derived from genes associated with CRP levels did not predict risk of total knee or hip replacement for osteoarthritis.”

“Our findings do not support a role of low-grade systemic inflammation as indicated by C-reactive protein in the risk of total knee or hip replacement for osteoarthritis among women. Although we did not observe an association between C-reactive protein and risk of total knee or hip replacement for osteoarthritis, some studies have suggested that systemic inflammation may play a greater role early in the disease course than in end-stage osteoarthritis.”

“This may partly explain the lack of association in our study, since we examined only end-stage osteoarthritis as indicated by total joint replacement. Further research in diverse cohorts is needed to examine the relationship between C-reactive protein and osteoarthritis, particularly early in the disease.”