1 Departments of Orthopaedic Surgery (A.G.G., T.F.N.), Physical Therapy (K.W.), Physical Medicine and Rehabilitation (M.E.W.), and Neurosurgery (P.D.K.), and the James R. Gage Center for Gait and Motion Analysis (T.F.N, M.H.S.), Gillette Children's Specialty Healthcare St. Paul, Minnesota.