Retrospective study links SMA type 1 to higher hip instability prevalence in children

IntroductionHip instability is an important complication of spinal muscular atrophy (SMA), which leads to various functional impairments, including mobility challenges and difficulties with daily care. The primary objective of this study is to determine the prevalence and severity of hip instability in a cohort of SMA patients managed at a tertiary care center. The prevalence of scoliosis and its association with hip instability in children with SMA were also assessed.MethodsThis is a retrospective cross-sectional study including children with a genetic diagnosis of SMA and available hip x-rays, conducted between 2018 and 2023. Patients were grouped based on SMA type and motor status (non-sitters, sitters, or walkers). Relevant parameters were collected including hip subluxation/dislocation, presence of scoliosis, number of SMN2 copies and disease modifying therapies (DMTs) received.ResultsFifty-four children with types 1–3 SMA were included in this study. Hip dislocation/subluxation in both hips was most prevalent in type 1 SMA patients [Fisher's Exact Test (FET): p = 0.046]. There was no significant correlation between the presence of hip subluxation or dislocation and scoliosis, but patients with fewer SMN2 copies were more likely to have scoliosis (p = 0.023). Several factors, including gender, age, motor status and presence of scoliosis were analysed, but none showed a statistically significant association with hip abnormalities.DiscussionTo the best of our knowledge, this is the first study in the Middle East on hip instability and scoliosis in a cohort of children with SMA. Hip dislocation and/or subluxation is most common and most severe in type 1 SMA. The study's findings can aid the development of hip instability screening programs in SMA patients, enabling early intervention.