Introduction: Osteoarthritis (OA) and haemophilic arthropathy (HA) are clinically similar, but pathologically distinct conditions which result in joint pain and loss of function. Distinguishing their disease mechanisms is therefore a key step in the development of curative therapy, as opposed to current symptomatic treatments. A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) 4 is a metzincin‐family member proteoglycan with known local involvement in OA pathogenesis.Aim: To investigate the potential differences and discriminatory potential of ADAMTS‐4 between OA and HA patients.Methods: We determined ADAMTS‐4 plasma concentrations by ELISA in patients with HA and OA. This pilot cross‐sectional study included N = 40 male participants equally divided across four subgroups: haemophilia patients with severe or mild HA and control subjects with severe or mild/no OA.Results: Our study showed a striking elevation in plasma ADAMTS‐4 expression levels in HA patients as compared to OA, as well as an increase in patients with severe as compared to mild HA. By performing the binomial logistical analysis and fitting the receiver–operator curve (ROC) (cut‐off probability .5), ADAMTS‐4 had a sensitivity of 95% and specificity of 50% in discriminating between HA and OA among our study participants.Conclusion: Uncovering the marked differences in plasma levels of ADAMTS‐4 in patients with HA versus OA potentially sheds new light on the mechanisms of HA pathogenesis and could foster more research into the roles ADAMTS‐4 and other matrix metalloproteinases (MMPs) play in HA versus OA.

Objectives: This study aims to assess the impact of a Tai Chi exercise program (TCEP) on pain, spinal flexibility, muscle strength, stability and balance, functional status, and quality of life (QoL) among home-dwelling patients with osteoarthritis (OA) or inflammatory arthritis (iA). Patients and methods: Between October 2018 and April 2019, a total of 28 participants (4 males, 24 females; median age: 62 years; range, 34 to 79 years) who completed the training program participating in at least 18 sessions were included. The TCEP consisted of 50 sessions for 60 min twice a week. The average attendance rate was high (78%, 39 sessions). Results: Chest mobility (breathing index, p<0.001), sagittal mobility of cervical (p<0.001), thoracic (p=0.009), and lumbar spine (Schober’s test, p<0.001) improved significantly in participants with OA and iA. The improvement in functional status was significant only in participants with OA (Lequesne index, p=0.014). Although the change in Lequesne index was statistically significant, the median value remained in the range of severe disability and the change did not reach the minimal clinically important difference. Although the trends were positive, the changes in pain (Visual Analog Scale pain, p=0.599), stability and balance (functional reach test, p=0.341), muscular strength (wall sit test, p=0.069), and health-related QoL (15D, p=0.065) were non-significant in participants with OA and iA. Conclusion: Our study results suggest that a 25-week TCEP is safe and can improve chest and spinal mobility in home-dwelling individuals with OA or iA.