Background Hand osteoarthritis (OA) hallmarks on radiographs like osteophytes (OP) and joint space narrowing (JSN) are signs of “late” damage, indicating an already long-lasting disease process. As therapies should be targeted at stopping or slowing the disease process, measures of an earlier stage of the disease process of OA are warranted.
We showed in ultrasonography studies that synovitis is associated with radiographic progression after two years. MRI is able to visualize synovitis and additionally bone marrow lesions (BMLs), giving information about processes in the subchondral bone. Currently, the meaning of these features in progression in hand OA is still unclear.
Objectives Therefore, we aimed to assess whether BMLs and synovitis are associated with radiographic progression after a relatively short follow-up (FU) of two years.
Methods Data were used of the HOSTAS (Hand OSTeoArthritis in Secondary care) study, which includes consecutive patients diagnosed by their treating rheumatologist with primary hand OA. This analysis concerned patients who received a contrast-enhanced MRI at baseline (BL) of the right hand DIP 2-5 and PIP 2-5 joints.
Radiographs were made at BL and after two years and scored paired in known order, blinded for patient characteristics, according to the Kellgren-Lawrence (KL) method (0-4) and the OARSI atlas (OP (0-3) and JSN (0-3)). Radiographic progression was defined as an increase in score of at least 1 after two years.
MRIs were scored following the Oslo hand OA score for synovitis (0-3) and BMLs (0-3). Due to few observations grades 2 and 3 were merged. Reliability of the scoring was good.
ORs with 95% CIs were calculated using generalised estimating equations (GEE) to associate MRI features at BL with radiographic progression at FU on joint level, adjusting for age, sex, BMI and patient effect. Joints with KL score 4 or OARSI scores 3 at BL were excluded, as they could not further progress.
Results MRIs on baseline were made in 106 patients, of which 88 patients (82% women, mean age 59 years, median BMI 27 kg/m2) had FU radiographs available. 703 joints were involved in the current analyses: 331 had a KL BL-score of 0, 190 of 1, 111 of 2, 43 of 3 and 28 of 4. After two years, 78 (11%) joints in 46 (52%) patients had progressed.
GEE showed independent associations for synovitis and KL progression. The association was also found for BMLs independent of synovitis, but only in grades 2 and 3 (table 1). KL BL-scores were not significantly associated with KL progression. Comparable results were found when analyses were done for OP or JSN progression instead of KL. Since JSN at BL showed a significant association with JSN progression, analyses were adjusted for BL JSN scores.
Conclusions In hand OA patients, synovitis on MRI shows an independent association with radiographic progression after two years. BMLs at BL also associate with progression, but only when these are strongly present (i.e. grade 2/3). These findings indicate that synovitis and BMLs are an important part of the disease process. These MRI features could also serve as a biomarker identifying joints prone to develop OA or progress in the disease in an earlier stage.
Disclosure of Interest None declared