Arthrogryposis multiplex congenita (AMC) refers to a rare disease spectrum characterized by the presence of joint contractures at birth in at least two different body areas. Causes are multiple. Amyoplasia and distal arthrogryposes are the most frequent causes. Phenotypes consist of muscle weakness and atrophy of variant severity and joint deformities. The impact on mobility, activities or daily living and participation is variable (Dai et al, 2018).~Mercuri et al. (Mercuri et al, 2002) have developed a semi-quantitative score to mesure fibro-adipous muscle infiltration on muscle MRI.~Correlations between fibro-adipous infiltration and muscular deficits have already been studied in other neuromusclar diseases such as Pompe disease (Figueroa-Bonaparte et al, 2016) or Duchenne muscular dystrophy (Brogan et al, 2018). These studies revealed good correlation between disease onset, muscle strength and the degree of muscle fibro-adipous infiltration, calculated using the Mercuri score. The authors concluded that muscular MRI can be used to follow the neuromuscular disease progression as it is correlated with muscle function.~Contrary to these progressive diseases, AMC is a congenital non progressive condition. It is therefore tempting to hypothesize that the muscular fibro-adipous infiltration in these patients could be of prognostic value for future capacities.~Our aim is to evaluate the fibro-adipous muscle infiltration in a thoroughly phenotyped cohort of adult patients with Amyoplasia and Distal Arthrogryposes using the Mercuri score, based on muscular MRI, in order to evaluate the correlation with deficiencies, activity limitations and social participation.
The aim is to evaluate the correlation of quantified fibro-adipous infiltration of muscles, using the MRI-based Mercuri score, with deficiencies, activity limitations and social participation in patients with arthrogryposis multiplex congenita.