title: Preliminary evaluation of a robotic apparatus for the analysis of passive glenohumeral joint kinematics.
abstract: BACKGROUND
  The shoulder has the greatest range of motion of any joint in the human body. This is due, in part, to the complex interplay between the glenohumeral (GH) joint and the scapulothoracic (ST) articulation. Currently, our ability to study shoulder kinematics is limited, because existing models isolate the GH joint and rely on manual manipulation to create motion, and have low reproducibility. Similarly, most established techniques track shoulder motion discontinuously with limited accuracy.
  
  
  METHODS
  To overcome these problems, we have designed a novel system in which the shoulder girdle is studied intact, incorporating both GH and ST motions. In this system, highly reproducible trajectories are created using a robotic actuator to control the intact shoulder girdle. High-speed cameras are employed to track retroreflective bone markers continuously.
  
  
  RESULTS
  We evaluated this automated system's capacity to reproducibly capture GH translation in intact and pathologic shoulder conditions. A pair of shoulders (left and right) were tested during forward elevation at baseline, with a winged scapula, and after creation of a full thickness supraspinatus tear.
  
  
  CONCLUSIONS
  The system detected differences in GH translations as small as 0.5 mm between different conditions. For each, three consecutive trials were performed and demonstrated high reproducibility and high precision.
authors.affiliation: Orthopaedic Department, University Hospital Basel, University of Basel, Basel, Switzerland.
authors.forename: Claudio
authors.initials: C
authors.lastname: Rosso
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Müller
authors.forename: Vahid
authors.initials: V
authors.lastname: Entezari
authors.forename: William A
authors.initials: WA
authors.lastname: Dow
authors.forename: Brett
authors.initials: B
authors.lastname: McKenzie
authors.forename: Stacey K
authors.initials: SK
authors.lastname: Stanton
authors.forename: Daniel
authors.initials: D
authors.lastname: Li
authors.forename: Andrea
authors.initials: A
authors.lastname: Cereatti
authors.forename: Arun J
authors.initials: AJ
authors.lastname: Ramappa
authors.forename: Joseph P
authors.initials: JP
authors.lastname: DeAngelis
authors.forename: Ara
authors.initials: A
authors.lastname: Nazarian
authors.forename: Ugo
authors.initials: U
authors.lastname: Della Croce
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D004867:Equipment Design; D006801:Humans; D010780:Photogrammetry / Q000295:instrumentation / Q000379:methods; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012371:Robotics / Q000295:instrumentation* / Q000379:methods; D017006:Rotator Cuff / Q000601:surgery; D000070636:Rotator Cuff Injuries; D012785:Shoulder Joint / Q000502:physiology* / Q000503:physiopathology