PROJECT SUMMARY/ABSTRACTOver 40000 children in the US are hospitalized for musculoskeletal deformities each year. Abnormal and oftendiminished skeletal growth is the root cause of many of these conditions. For years periosteal resection hasbeen shown to accelerate longitudinal bone growth. Previous attempts to surgically exploit this phenomenonas a growth accelerating therapeutic modality have produced variable results that have not justified theprocedures surgical morbidity and has been a major barrier to widespread clinical use. Recently we havedeveloped technology capable of performing these procedures non-invasively. However the currenttechnology lacks the necessary targeting and imaging capabilities to measure and ensure proper energydelivery at the bone surface. Furthermore the exact portion of the periosteum that must be injured toaccelerate growth is unclear. Thus in the first aim we will determine the component of the periosteum injuredduring open surgical periosteal resection responsible for physeal growth acceleration and in the second aim wewill integrate targeting capabilities into our system to allow precise placement of energy on the periosteum tominimize adjacent soft tissue injury. At the completion of the proposed work we will have furthered our goal ofdeveloping a simple non-invasive method to modulate skeletal growth.