title: Gait symmetry and regularity in transfemoral amputees assessed by trunk accelerations.
abstract: BACKGROUND
  The aim of this study was to evaluate a method based on a single accelerometer for the assessment of gait symmetry and regularity in subjects wearing lower limb prostheses.
  
  
  METHODS
  Ten transfemoral amputees and ten healthy control subjects were studied. For the purpose of this study, subjects wore a triaxial accelerometer on their thorax, and foot insoles. Subjects were asked to walk straight ahead for 70 m at their natural speed, and at a lower and faster speed. Indices of step and stride regularity (Ad1 and Ad2, respectively) were obtained by the autocorrelation coefficients computed from the three acceleration components. Step and stride durations were calculated from the plantar pressure data and were used to compute two reference indices (SI1 and SI2) for step and stride regularity.
  
  
  RESULTS
  Regression analysis showed that both Ad1 well correlates with SI1 (R2 up to 0.74), and Ad2 well correlates with SI2 (R2 up to 0.52). A ROC analysis showed that Ad1 and Ad2 has generally a good sensitivity and specificity in classifying amputee's walking trial, as having a normal or a pathologic step or stride regularity as defined by means of the reference indices SI1 and SI2. In particular, the antero-posterior component of Ad1 and the vertical component of Ad2 had a sensitivity of 90.6% and 87.2%, and a specificity of 92.3% and 81.8%, respectively.
  
  
  CONCLUSIONS
  The use of a simple accelerometer, whose components can be analyzed by the autocorrelation function method, is adequate for the assessment of gait symmetry and regularity in transfemoral amputees.
authors.affiliation: Department of Electronics, Computer Science and Systems, University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tura
authors.forename: Michele
authors.initials: M
authors.lastname: Raggi
authors.forename: Laura
authors.initials: L
authors.lastname: Rocchi
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Cutti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Chiari
mesh_terms: D000054:Acceleration; D000674:Amputees / Q000534:rehabilitation*; D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation* / Q000379:methods; D012372:ROC Curve; D012046:Rehabilitation / Q000295:instrumentation*; D012680:Sensitivity and Specificity