title: Design and manufacture of a novel system to simulate the biomechanics of basic and pitching shoulder motion.
abstract: OBJECTIVE
  Cadaveric models of the shoulder evaluate discrete motion segments using the glenohumeral joint in isolation over a defined trajectory. The aim of this study was to design, manufacture and validate a robotic system to accurately create three-dimensional movement of the upper body and capture it using high-speed motion cameras.
  
  
  METHODS
  In particular, we intended to use the robotic system to simulate the normal throwing motion in an intact cadaver. The robotic system consists of a lower frame (to move the torso) and an upper frame (to move an arm) using seven actuators. The actuators accurately reproduced planned trajectories. The marker setup used for motion capture was able to determine the six degrees of freedom of all involved joints during the planned motion of the end effector.
  
  
  RESULTS
  The testing system demonstrated high precision and accuracy based on the expected versus observed displacements of individual axes. The maximum coefficient of variation for displacement of unloaded axes was less than 0.5% for all axes. The expected and observed actual displacements had a high level of correlation with coefficients of determination of 1.0 for all axes.
  
  
  CONCLUSIONS
  Given that this system can accurately simulate and track simple and complex motion, there is a new opportunity to study kinematics of the shoulder under normal and pathological conditions in a cadaveric shoulder model.
authors.affiliation: Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, USA.
authors.forename: V
authors.initials: V
authors.lastname: Entezari
authors.forename: B L
authors.initials: BL
authors.lastname: Trechsel
authors.forename: W A
authors.initials: WA
authors.lastname: Dow
authors.forename: S K
authors.initials: SK
authors.lastname: Stanton
authors.forename: C
authors.initials: C
authors.lastname: Rosso
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: B
authors.initials: B
authors.lastname: McKenzie
authors.forename: V
authors.initials: V
authors.lastname: Vartanians
authors.forename: A
authors.initials: A
authors.lastname: Cereatti
authors.forename: U
authors.initials: U
authors.lastname: Della Croce
authors.forename: J P
authors.initials: JP
authors.lastname: Deangelis
authors.forename: A J
authors.initials: AJ
authors.lastname: Ramappa
authors.forename: A
authors.initials: A
authors.lastname: Nazarian
keywords: Motion analysis; Pitching; Range of motion; Shoulder; Shoulder biomechanics; Shoulder kinematics