This research study is looking at risk factors for developing Thoracic Insufficiency in children with Larsen's Syndrome. We are looking for children ages 6-18 who have been diagnosed with Larsen's Syndrome. Participants will be asked to undergo a physical exam, X-Rays, an MRI, and a Pulmonary Function Test. If interested, please contact Nirupa Galagedera (galagedern@email.chop.edu or 215-590-1943) or Carina Lott (lottc@email.chop.edu or 267-426-0287).