title: Outcome analysis after helmet therapy using 3D photogrammetry in patients with deformational plagiocephaly: the role of root mean square.
abstract: Deformational plagiocephaly (DP) is a multifactorial non-synostotic cranial deformity with a reported incidence as high as 1 in 7 infants in North America. Treatment options have focused on non-operative interventions including head repositioning and the use of an orthotic helmet device. Previous studies have used linear and two dimensional outcome measures to assess changes in cranial symmetry after helmet therapy. Our objective was to demonstrate improvement in head shape after treatment with a cranial molding helmet by using Root Mean Square (RMS), a measure unique to 3D photogrammetry, which takes into account both changes in volume and shape over time. Three dimensional photographs were obtained before and after molding helmet treatment in 40 infants (4-10 months old) with deformational plagiocephaly. Anatomical reference planes and measurements were recorded using the 3dMD Vultus(®) analysis software. RMS was used to quantify symmetry by superimposing left and right quadrants and calculating the mean value of aggregate distances between surfaces. Over 95% of the patients demonstrated an improvement in symmetry with helmet therapy. Furthermore, when the sample of infants was divided into two treatment subgroups, a statistically significant correlation was found between the age at the beginning of treatment and the change in the RMS value. When helmet therapy was started before 7 months of age a greater improvement in symmetry was seen. This work represents application of the technique of RMS analysis to demonstrate the efficacy of treatment of deformational plagiocephaly with a cranial molding helmet.
authors.affiliation: The Hospital for Sick Children, Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada.
authors.forename: Mahsa Bidgoli
authors.initials: MB
authors.lastname: Moghaddam
authors.affiliation: The Hospital for Sick Children, Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada.
authors.forename: Trevor M
authors.initials: TM
authors.lastname: Brown
authors.affiliation: The Hospital for Sick Children, Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada.
authors.forename: April
authors.initials: A
authors.lastname: Clausen
authors.affiliation: The Hospital for Sick Children, Center for Orthotics and Medical Devices, Children's Orthotics Clinic, 555 University Ave, Toronto, ON M5G 1X8, Canada.
authors.forename: Trevor
authors.initials: T
authors.lastname: DaSilva
authors.affiliation: The Hospital for Sick Children, Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada.
authors.forename: Emily
authors.initials: E
authors.lastname: Ho
authors.affiliation: The Hospital for Sick Children, Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Toronto, 555 University Ave, Toronto, ON M5G 1X8, Canada. Electronic address: christopher.forrest@sickkids.ca.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Forrest
mesh_terms: D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007223:Infant; D008297:Male; D055641:Mathematical Concepts; D009989:Orthotic Devices; D010780:Photogrammetry; D059041:Plagiocephaly / Q000473:pathology* / Q000628:therapy*; D012189:Retrospective Studies; D012886:Skull / Q000473:pathology; D016896:Treatment Outcome
keywords: Cranial molding orthosis; Deformational plagiocephaly; Molding helmet; Photogrammetry; Root mean square; Three dimensional imaging