title: Letter to the Editor: Response to Grivas et al.
authors.affiliation: Division of Orthopaedics, University of Missouri Kansas City, University of Kansas, Children's Mercy Hospital, 2401 Gillham Road, Kansas City, MO 64108, USA. Electronic address: rmschwend@cmh.edu.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Schwend
authors.affiliation: K2M Inc., 751 Miller Drive SE, Leesburg, VA 20175, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Schmidt
authors.affiliation: K2M Inc., 751 Miller Drive SE, Leesburg, VA 20175, USA.
authors.forename: Julie L
authors.initials: JL
authors.lastname: Reigrut
authors.affiliation: Department of Orthopaedics and Rehabilitation, University of Florida College of Medicine, University of Florida Orthopaedics and Sports Medicine Institute, FL 32611-2727, USA.
authors.forename: Laurel C
authors.initials: LC
authors.lastname: Blakemore
authors.affiliation: University of California, 6190 Cornerstone CT, Ste 212, San Diego, CA 92121, USA.
authors.forename: Behrooz A
authors.initials: BA
authors.lastname: Akbarnia