Characteristics of patients presenting with concomitant carpal tunnel syndrome at the initial diagnosis with rheumatoid arthritis.

OBJECTIVE: To investigate the clinical characteristics of patients who presented with concomitant carpal tunnel syndrome (CTS) at the initial diagnosis with rheumatoid arthritis (RA). METHODS: We analyzed patients with newly diagnosed RA at a single institution between 2012 and 2021. Patient demographic and laboratory data, the 2010 ACR/EULAR classification criteria, and the duration from the initial visit to RA diagnosis were compared between RA patients with concomitant CTS (RA with CTS group) and those without CTS (RA without CTS group). RESULTS: The study included 235 patients (157 females), of which 11 patients (4.7%) presented with CTS at the initial diagnosis with RA. In the RA with CTS group, the age was significantly higher (P = .033), all patients were female, and anti-cyclic citrullinated peptide antibody (ACPA) was negative, and the duration to RA diagnosis was longer than in the RA without CTS group. Among all RA with CTS patients, ultrasonography showed power Doppler signal-positive tenosynovitis in the carpal tunnel, which is not usually detected in idiopathic CTS. CONCLUSIONS: Patients with concomitant CTS at the initial diagnosis with RA were characterized by old age, female sex, and negative ACPA. Patients with symptoms of CTS should undergo ultrasonography for early diagnosis of RA.

A case of septic arthritis of the elbow joint in rheumatoid arthritis diagnosed by arthroscopic synovectomy.

We report a case of methicillin-resistant Staphylococcus aureus (MRSA) septic arthritis of the elbow detected by arthroscopic synovectomy in an 81-year-old woman with rheumatoid arthritis (RA) who was initially diagnosed with a rheumatoid arthritis flare-up. The patient was administered abatacept, an antirheumatic biological agent, as the synovial fluid culture was negative. Destruction of the joint progressed despite medication, and the patient underwent arthroscopic synovectomy. MRSA was detected in the culture of the synovium that was collected intraoperatively, and septic arthritis was diagnosed. The infection subsided with anti-MRSA antibiotics, but the patient continued to experience moderate pain and limited motion. In RA patients, it might be difficult to differentiate minor findings from infection. Arthroscopic synovectomy is one of the selectable procedures that should be actively considered when infection is suspected.

Rheumatoid Arthritis Onset from Shoulder Monoarthritis.

PURPOSE: To investigate the incidence and clinical characteristics of rheumatoid arthritis (RA) presenting with shoulder monoarthritis. PATIENTS AND METHODS: Our study included 113 patients (77 females; mean age, 63.0 ± 13.1 years) whom we newly diagnosed with RA in 2012-2016. We investigated cases with onset from shoulder monoarthritis. Specifically, we examined physical findings, blood test results, radiographic findings, magnetic resonance imaging (MRI) findings, and duration from initial visit to diagnosis. RA was diagnosed based on the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria. RESULTS: Overall, mean 2010 ACR/EULAR criteria score was 6.8 ± 1.8, and median duration to diagnosis was 3 days (interquartile range: 0-14). Two patients (1.8%) were identified as having RA with onset from shoulder monoarthritis. Both were late middle-aged women with MRI findings of rotator cuff tear and remarkable synovial proliferation. However, neither patient fulfilled the 2010 ACR/EULAR criteria. It took 85 and 98 days to make a definitive diagnosis, respectively. CONCLUSION: Early diagnosis is difficult when RA synovitis develops from shoulder monoarthritis, especially, in elderly patients who have a rotator cuff tear. In addition to MRI, culture-based and pathological examinations may be helpful for early diagnosis of RA.

Effect of a cathepsin K inhibitor on arthritis and bone mineral density in ovariectomized rats with collagen-induced arthritis.

OBJECTIVES: Cathepsin K is expressed by osteoclasts and synovial fibroblasts and degrades key components of bone and cartilage. Inhibition of cathepsin K protease activity may be beneficial for the prevention of bone erosion and cartilage degradation in rheumatoid arthritis (RA). The collagen-induced arthritis (CIA) rat model is well established for studying the pathology and treatment of RA. We investigated the effect of ONO-KK1-300-01, a cathepsin K inhibitor (CKI), on arthritis and bone mineral density (BMD) in rats with CIA. METHODS: Seven-month-old female Sprague Dawley rats were divided into 5 groups: rats without CIA (CNT); CIA rats that underwent ovariectomy (OVX) and were treated with CKI; CIA rats that underwent OVX and were treated with vehicle (Veh); CIA rats that underwent sham surgery and were treated with CKI; and CIA rats that underwent sham surgery and were treated with Veh. CKI was orally administered at a dose of 15 mg/kg, thus initiating collagen sensitization, until death at 4 weeks. We evaluated hind paw thickness and the arthritis score every week until death. Radiographs of the resected left foot were obtained with a soft X-ray apparatus. Destruction of bone and cartilage was classified and scored as previously described by Engelhardt et al. BMD was measured by bone densitometry at the halfway point between the distal metaphysis and the diaphysis of the resected right femur. We also performed histomorphometry of the proximal left tibia, histological evaluation of arthritis, and a bone strength test. RESULTS: CKI administration significantly reduced hind paw thickness and the arthritis score, and prevented a decrease in BMD. The radiographic score was significantly lower in the CKI group than in the Veh group. In the histomorphometric analysis, bone-resorption parameters were significantly lower in the CKI groups than in the Veh groups. CKI significantly inhibited synovial proliferation in the CIA rats. In the bone strength test, the ultimate stress was significantly higher in the CKI groups than in the Veh groups. CONCLUSION: Our findings indicate that cathepsin K inhibitors may inhibit systemic and local bone loss, ameliorate arthritis, and attenuate the decrease of bone strength in an animal model of arthritis.