Deep Phenotyping Gait Deficits in Orthopedic Manifestations of Pediatric Cancer Patients

Inclusion Criteria Cases: * Participant requiring orthopedic surgery due to a diagnosis of lower limb bone sarcoma, soft tissue sarcoma, or steroid-induced avascular necrosis (Appendix III) and will receive further additional treatment and/or follow-up care at St. Jude. * Participant is between the ages of ≥5 and ≤20 years old at the time of enrollment. Controls: * Participant is between the ages of ≥5 and ≤20 years old at the time of enrollment. * Participant (or their parent/legal guardian) considers themself healthy for their age. * Participant (or their parent/legal guardian) reports being able to participate in normal daily activities of life with respect to their age. Exclusion Criteria Cases: * Individuals with pre-existing genetic/congenital disorders affecting gait will be excluded e.g., cerebral palsy. * Individuals who are unable to follow age-appropriate instructions during the gait assessment. * Inability or unwillingness of research participant or legal guardian/representative to give written informed consent. * Individuals diagnosed with radiation-induced avascular necrosis. Controls: * Individuals who are unable to follow age-appropriate instructions during the gait assessment. * Individuals who self-report health conditions affecting gait and mobility. * Individuals who have the following conditions: diabetes mellitus due to impaired circulation, sensation and strength, malignant cancers, demyelinating inflammatory and degenerative neurological conditions, pregnancy, obesity (BMI \>40 kg/m2), severe cardiac or pulmonary disease affecting performance of daily activities, history of major surgery affecting gait and mobility, infections or inflammatory arthropathies, severe mobility impairment necessitating dependence on mobility aids for all ambulation. * Individual or legal guardian/representative is unable or unwilling to give written informed consent.