Defining Treatment Outcomes and Genetic Architecture in Idiopathic Toe Walking*

Toe walking is a very common diagnosis in children with a prevalence of 5% -24%. Persistent toe walking in children over 3 years of age often results in parental concern, provoking multiple medical visits, and a range of interventions. Additionally, toe walking has both social implications and concerns for increased foot and ankle pain in those with contracture. Idiopathic toe walking (ITW) is a diagnosis of exclusion and affirming the diagnosis, ascertaining if intervention is indicated, and determining the optimal timing and intervention strategy are not well defined in the literature. As a family history of toe walking is reported in many children with ITW, there is a strong possibility that a subset of children may have a genetic cause for the condition which may impact the clinical course and outcome of treatment. Several approaches to intervention have been suggested to address toe-walking including: observation, therapy, casting, botulinum toxin A as well as surgery to lengthen the gastroc-soleus complex at the level of the calf or Achilles tendon. The purpose of this multi-center study is to examine a well-defined cohort of children with ITW utilizing a combination of quantitative measurement tools, parent reported outcomes, and whole genome sequencing to promote an evidence-based approach to orthopaedic management of this population. One hundred and eighty children who meet the inclusion/exclusion criteria for this study will be recruited from 8 participating SHC sites (POR, NCA, SLC, CHI, PHL, SPO, GRN, LEX) and treated with either serial casting or surgery. Children will be assessed 3 times over 1 year (Baseline, 6-months and 1-year post intervention). A series of screening as well as delineated inclusion/exclusion criteria will be used to ensure the diagnosis of ITW. Clinical assessments, radiographs and 3-D gait analysis utilizing electromyography and a multi-segment foot model will be used to determine if there are differences in the range of motion, gait kinematics and kinetics, motor synergies and foot contact patterns following casting or surgery. Whole genome sequencing will be used to determine if there is a genetic basis for ITW can be identified. Analysis will focus on 1) comparing and contrasting the short and long-term outcomes following non-operative (casting) and surgical intervention to determine if one approach is more efficacious, 2) identify potential genetic determinants for ITWp and 3) identify the factors that mediate and moderate intervention efficacy. The knowledge gained from this study will promote development of an evidence-based and personalized approach to the management of ITW.