Future studies should investigate whether the relative proportions of these two FAP/CD90 fibroblasts subsets are an indicator of a phenotype of OA, as it could be hypothesised based on the findings in RA that a high proportion of FAP+CD90+ fibroblasts could result in a more inflammatory disease phenotype, while a high proportion of FAP+CD90− fibroblasts might be linked to a more cartilage-destructive disease phenotype. Here, FAP is linked to rheumatoid arthritis.