Comparison of histological and morphometrical changes underlying subchondral bone abnormalities in inflammatory and...

Subchondral bone abnormalities (SBAs) on magnetic resonance imaging (MRI) are observed frequently and associated with disease course in various musculoskeletal disorders. This review aims to map the existing knowledge of their underlying histological features, and to identify needs for future research.

We conducted a systematic review following PRISMA guidelines until September 2017, including all studies correlating histological features to on MRI defined SBAs in patients with osteoarthritis (OA), rheumatoid arthritis (RA), spondyloarthritis (SpA) and degenerative disc disease (DDD). Two authors independently retrieved articles and assessed study quality.

A total of 21 studies (466 patients) correlated histological features to SBAs in OA (n = 13), RA (n = 3), ankylosing spondylitis (AS) (n = 1) and DDD (n = 4). Reported changes in OA were substitution of normal subchondral bone with fibrosis and necrosis, and increased bone remodeling. In contrast, in RA, AS or DDD fibrosis was not reported and SBAs correlated to an increase in inflammatory cell number. In DDD necrosis was observed. Similar to OA, increased bone remodeling was shown in RA and DDD. The risk of bias assessment showed a lack in described patient criteria, blinding and/or adequate topographic correlation in approximately half of studies. There was heterogeneity regarding the investigated histological features between the different disorders.

Current studies suggest that SBAs correlate to various histological features, including fibrosis, cell death, inflammation and bone remodeling. In the majority of studies most quality criteria were not met. Future studies should aim for high quality research, and consistency in investigated features between different disorders.