title: A new methodology for assessment of pectus excavatum correction after bar removal in Nuss procedure: Preliminary study.
abstract: OBJECTIVE
  The objective is to present a new methodology to assess quantitatively the impact of bar removal on the anterior chest wall, among patients with pectus excavatum who have undergone the Nuss procedure, and present a preliminary study using this methodology.
  
  
  METHODS
  We propose to acquire, for each patient, the surface of the anterior chest wall using a three-dimensional laser scanner at subsequent time points (short term: before and after surgery; long term: follow-up visit, 6months, and 12months after surgery). After surfaces postprocessing, the changes are assessed by overlapping and measuring the distances between surfaces. In this preliminary study, three time points were acquired and two assessments were performed: before vs after bar removal (early) and before vs 2-8weeks after bar removal (interim). In 21 patients, the signed distances and volumes between surfaces were computed and the data analysis was performed.
  
  
  RESULTS
  This methodology revealed useful for monitoring changes in the anterior chest wall. On average, the mean, maximum, and volume variations, in the early assessment, were -0.1±0.1cm, -0.6±0.2cm, and 47.8±22.2cm3, respectively; and, in the interim assessment, were -0.5±0.2cm, -1.3±0.4cm, and 122.1±47.3cm3, respectively (p<0.05). Data analysis revealed that the time the bar was in situ was inversely and significantly correlated with postretraction and was a relevant predictor of its decrease following surgery (p<0.05). Additionally, gender and age suggested influencing the outcome.
  
  
  CONCLUSIONS
  This methodology is novel, objective and safe, helping on follow-up of pectus excavatum patients. Moreover, the preliminary study suggests that the time the bar was in situ may be the main determinant of the anterior chest wall retraction following bar removal. Further studies should continue to corroborate and reinforce the preliminary findings, by increasing the sample size and performing long-term assessments.
  
  
  METHODS
  III.
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT, Government Associate Laboratory, Braga/Guimarães, Portugal. Electronic address: joaofonseca@med.uminho.pt.
authors.forename: João
authors.initials: J
authors.lastname: Gomes-Fonseca
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT, Government Associate Laboratory, Braga/Guimarães, Portugal; DIGARC-Technology School, Polytechnic Institute of Cávado and Ave, Barcelos, Portugal.
authors.forename: João L
authors.initials: JL
authors.lastname: Vilaça
authors.affiliation: Department of Pediatric Surgery, Centro Hospitalar de São João, Porto, Portugal; Department of Pediatrics, Faculty of Medicine, University of Porto, Porto, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Henriques-Coelho
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT, Government Associate Laboratory, Braga/Guimarães, Portugal; Department of Orthopedics, Hospital de Braga, Braga, Portugal.
authors.forename: Bruno
authors.initials: B
authors.lastname: Direito-Santos
authors.affiliation: Department of Mechanical Engineering, School of Engineering, University of Minho, Guimarães, Portugal.
authors.forename: António C M
authors.initials: ACM
authors.lastname: Pinho
authors.affiliation: Department of Industrial Electronics, School of Engineering, University of Minho, Guimarães, Portugal.
authors.forename: Jaime C
authors.initials: JC
authors.lastname: Fonseca
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's-PT, Government Associate Laboratory, Braga/Guimarães, Portugal; Department of Pediatric Surgery, Hospital de Braga, Braga, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Correia-Pinto
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D020878:Device Removal; D005260:Female; D005500:Follow-Up Studies; D005660:Funnel Chest / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D007834:Lasers; D008297:Male; D019637:Orthopedic Procedures / Q000295:instrumentation; D035441:Thoracic Wall / Q000000981:diagnostic imaging* / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult
keywords: 3D surface analysis; 3D surface scanning; Nuss procedure; Pectus excavatum; Postretraction