title: Development and evaluation of a novel low-cost sensor-based knee flexion angle measurement system.
abstract: BACKGROUND
  Knee injuries form a large part of musculoskeletal trauma in sporting activities and the rehabilitation can require a long period, for both the patients and the specialists, to restore healthy condition. A reliable, portable, and low-cost system that could allow quick, simple, and effective measurement of knee flexion angles would greatly improve the evaluation of the rehabilitation process and the subsequent planning procedure, with meaningful reduction of recovery time and cost.
  
  
  METHODS
  A novel tool for nonstop measurements of knee flexion angles based on the adoption of an elastic sensor embedded in an easy-to-realize wearable kneepad has been proposed. We fully characterized this tool in terms of accuracy, repeatability, and reliability of measure, and validated it against the gold-standard Vicon.
  
  
  RESULTS
  Our tool demonstrated good reproducibility and repeatability among testers (mean range of measures=5.82° ± 1.93°) and high accuracy (root mean square error<1.28°), together with good reliability (intraclass correlation coefficient between 0.80 and 0.91).
  
  
  CONCLUSIONS
  The proposed tool demonstrates good performance, is portable, cheap, easy to use, and allows automatic measurements, so as to be a valuable system for accurate nonstop measurement of knee angles.
  
  
  CONCLUSIONS
  Our sensor-based measurement system is suitable for the evaluation of the rehabilitation course after knee traumas, because it furnishes a low-cost but accurate monitor of knee flexion movements, during an amount of time as long as desired.
authors.affiliation: Department of Electronic Engineering, University "Tor Vergata", Via del Politecnico 1, 00133, Rome, Italy. Electronic address: saggio@uniroma2.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Saggio
authors.affiliation: Department of Electronic Engineering, University "Tor Vergata", Via del Politecnico 1, 00133, Rome, Italy.
authors.forename: Lucia R
authors.initials: LR
authors.lastname: Quitadamo
authors.affiliation: Department of Electronic Engineering, University "Tor Vergata", Via del Politecnico 1, 00133, Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Albero
mesh_terms: D000328:Adult; D053587:Arthrometry, Articular / Q000191:economics / Q000295:instrumentation*; D001915:Braces; D017097:Electric Impedance; D004867:Equipment Design; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results
keywords: Stretch sensor; knee motion; knee rehabilitation; reliability; repeatability