Performance of myotonometer in the assessment of skin involvement in systemic sclerosis

Objectives A clinically practical tool to assess skin biomechanical properties rapidly and accurately is still lacking. Our aim was to examine the intra- and inter-observer reproducibility of a myotonometer for objective skin property assessment in systemic sclerosis (SSc), comparing it with the modified Rodnan skin score (mRSS), and distinguishing patients from healthy controls. Method Thirty-four patients (21 limited and 13 diffuse SSc), and 31 age and gender-matched healthy controls were enrolled. Skin tone and stiffness were measured at four different anatomical sites (the forearm, hand, leg, and foot) using a myotonometer. The correlation between the mRSS and skin properties was assessed. Also, hand functionality was evaluated for possible correlations between the variables. The differences in skin properties between dcSSc and lcSSc patients, and healthy controls were assessed using variance analysis. Results Intra- and inter-examiner reproducibility were excellent (ICC = 0.70 to 0.98) for tone and stiffness except for non-dominant hand tone, which showed good reliability (ICC = 0.64 to 0.74). Stiffness and tone values of the hands, forearms, and feet significantly correlated with mRSS total score ( r = 0.40 to 0.71, p < 0.05). Additionally, tone and stiffness of the hands and forearms moderately correlated with hand function ( p < 0.05). Tone and stiffness values increased in patients with dcSSc compared to healthy controls, or patients with lcSSc, at the hands, forearms, and legs ( p < 0.05). Conclusions Our findings emphasize the potential utility of the myotonometer for assessing skin properties and differentiating SSc patients from controls, demonstrating its promise as a valuable clinical evaluation tool in this context. Key Points • The myotonometer displayed excellent intra- and inter-examiner reproducibility for assessing skin properties. • Skin tone and stiffness parameters well correlated with the mRSS scores. • The myotonometer can distinguish patients with diffuse cutaneous SSc from healthy controls.