Normal joint range of motion in children with Down syndrome.

Down syndrome (DS) is one of the most common chromosomal conditions that results in intellectual disability. Children with DS have many different inflammatory and noninflammatory conditions that can affect joint mobility leading to arthralgia and altered joint range of motion (ROM), and it is important to have normal reference values for comparison to determine the degree of impairment. The objective of this study was to establish normative joint ROM values, using a standardized measurement approach, for upper and lower joints of healthy children of both genders with DS. This study evaluated joint ROM in healthy males and females with DS who had no previous musculoskeletal pathology. Younger males have more ROM than females at the same age and both genders lose ROM with age but continue to have increased ROM in the ankles compared to children without DS. This study establishes optimal estimates of joint ROM in children with DS, and this information should be helpful to clinicians when assessment requires evaluation of joint ROM to know if evaluation falls within the normal ROM. This reference should be helpful to track joint disease progression over time or as part of a musculoskeletal screen for abnormal joint ROM in children with DS.

Down Syndrome-Associated Arthritis (DA): Diagnostic and Management Challenges.

Down syndrome (DS) is one of the most common birth defects in the United States, the most common genomic disorder of intellectual disability, and results from trisomy 21. This chromosome disorder causes an extensive, heterogenous phenotype that results in a broad presentation of symptoms that includes atlantoaxial instability, congenital heart defects, muscle hypotonia, hypothyroidism, hematologic disorders, recurrent infections, and autoimmune diseases. The autoimmune diseases are caused by immune system dysregulation that results in increased pro-inflammatory cytokines, along with other innate and adaptive immune system dysregulation. This is the likely cause of the increased risk of inflammatory arthritis or Down syndrome-associated arthritis (DA) seen in individuals with DS. Most individuals with DA present with polyarticular (five or more joints with arthritis at presentation of disease), rheumatoid factor and anti-nuclear antibody negative disease that is aggressive with bone and joint damage at presentation. There is notable delay in diagnosis of DA as there are no formal guidelines on screening or monitoring for inflammatory arthritis in individuals with DS. Once diagnosed, and despite aggressive therapy with disease modifying antirheumatic drugs, disease burden is high for those with DA. Therapy can also be challenging for those with DA as many require second and third-line disease modifying therapies. Many also struggle with medication toxicity and ineffectiveness that further causes challenges with management and outcomes. The purpose of this current review is to provide an up-to-date summary of the literature related to DA in children and adolescents with focus on presentation, diagnosis, and management considerations, along with current barriers that inhibit optimal care.