A majority of patients with thumb base osteoarthritis (OA) did not experience changes in thumb pain or MRI features over 2 years of follow-up, according to a study published in Arthritis Care & Research. However, researchers observed that patients with radiographic damage had changes in synovitis and bone marrow lesions (BMLs) on MRI that were associated with increased pain in the thumb base.
Investigators extracted data from patients with thumb base OA enrolled in an ongoing observational cohort (Hand Osteoarthritis in Secondary Care) who received care at a hospital in the Netherlands. The analysis included baseline and 2-year follow-up data. Baseline demographic and clinical characteristics were collected by a standardized questionnaire. At study visits, the thumb base was examined for pain upon palpation. The MRI images of the thumb joints were obtained at baseline and follow-up, and were scored using the Outcome Measures in Rheumatology thumb base OA MRI scoring system. Synovitis, BMLs, subchondral bone defects, cartilage space loss, and osteophytes were also scored. Logistic regression was performed to assess the relationship between baseline imaging features and clinical outcomes at follow-up, with models for the imaging features adjusted for radiographic damage.
The study included data from 165 patients (83.0% women; mean age at baseline, 60.7±8.3 years). At baseline, 93 (56.4%) patients reported frequent right thumb base pain in the past month, and 65 (39.4%) had pain on palpation. The MRI features of thumb base OA were highly prevalent at baseline, with 81.6% of patients presenting with synovitis or BMLs on at least 1 thumb base joint. At the 2-year follow-up visit, pain on palpitation had decreased or resolved in 19.4% of patients and increased or developed in 20% of them. The majority of patients had no change in MRI scores from baseline to follow-up.
Among patients who had synovitis or BML changes, just 1 joint was typically involved. Compared with patients with unchanged or decreased pain, those with increased pain were significantly more likely to have experienced increased synovitis (OR, 3.44; 95% CI, 1.28-9.3) and BMLs (OR, 5.1; 95% CI, 2.10-12.6).
Analyses were then stratified by the presence of baseline osteophytes. In patients without osteophytes at baseline, increased synovitis or BMLs predicted increased pain (OR, 4.3; 95% CI, 1.25-14.8). Among patients with osteophytes at baseline, an increase in inflammatory MRI features were stronger predictors of increased pain (OR, 11.0; 95% CI, 3.35-36.1). Investigators hypothesized that the large effect size was likely a result of interaction between synovitis and BML.
These data describe the 2-year course of pain and MRI features in patients with thumb base OA. While pain levels fluctuate over time, MRI features remained stable in a majority of study participants. Among patients who experienced increased pain, synovitis and BML also changed.
Study limitations included the small sample size and the use of analgesics, which may have led to an underestimation of patient pain.
“[W]hile radiographic damage may be the main determinant of pain in thumb base OA, this study shows that a change in inflammatory features in the thumb base may still have a relevant effect on pain,” the investigators wrote.
Disclosure: A study author declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
van Beest S, Kroon HM, Reijnierse M, Rosendaal FR, Kloppenburg M, Kroon FPB. Two-year changes in MRI-features and pain in thumb base osteoarthritis [published online June 17, 2020]. Arthritis Care Res (Hoboken). doi:10.1002/acr.24355