title: Ultrasound evaluation of the subacromial space in healthy subjects performing three different positions of shoulder abduction in both loaded and unloaded conditions.
abstract: BACKGROUND
  Subacromial space (SS) narrowing may result in unsafe contact of rotator cuff tendons and bursa with the acromion, possibly promoting rotator cuff pathologies and pain. We measured SS in asymptomatic subjects after three movements employed for shoulder muscles' training.
  
  
  METHODS
  Twenty-five males (age 24±5years; stature 175±8 cm; body mass 74±12 kg) underwent SS ultrasound evaluation while executing with (WL) and without (NL) 4-kg load: 90° shoulder abduction (SA) without humerus rotation (90°neutral); 90° SA maximal humeral external rotation (90°er); maximum SA (above 90°) during upright row (UR). For inter-operator reliability analysis, a subset of 12 subjects was assessed by two operators.
  
  
  RESULTS
  Intra/inter-operator reliability coefficients were high (ICC>0.87; standard error of measurement range: 0.23-0.51 mm; minimum detectable change range: 0.61-1.79 mm). ANOVA revealed significant differences between loads (p = 0.003, η2= 0.37) and angles (p < 0.001, η2= 0.72), and interaction (p = 0.004, η2= 0.45). Normalized SS values WL were higher at 90°ervs. 90°neutraland UR (p < 0.001 for both). Differences in NL were found between 90°neutraland both 90°er(p = 0.002) and UR (p = 0.009).
  
  
  CONCLUSIONS
  When holding a 4-kg load, SS is larger at 90°erthan at 90°neutraland UR shoulder abduction positions. In unloaded condition, SS at 90°neutralis reduced compared to 90°erand UR.
authors: Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milan, Italy. Electronic address: stefano.longo@unimi.it.
authors: Stefano
authors: S
authors: Longo
authors: Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milan, Italy; Unit of Orthopaedic Surgery and Traumatology, IRCCS Policlinico San Donato, Piazza Malan 1, 20097 San Donato Milanese, Italy.
authors: Alberto
authors: A
authors: Corradi
authors: Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milan, Italy.
authors: Giovanni
authors: G
authors: Michielon
authors: Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milan, Italy; Unit of Radiology, IRCCS Policlinico San Donato, Piazza Malan 1, 20097 San Donato Milanese, Italy.
authors: Francesco
authors: F
authors: Sardanelli
authors: Department of Biomedical Sciences for Health, Università degli Studi di Milano, Via Mangiagalli 31, 20133 Milan, Italy; Unit of Diagnostic and Interventional Radiology, IRCCS Istituto Ortopedico Galeazzi, Via Riccardo Galeazzi 4, 20161 Milano, Italy.
authors: Luca Maria
authors: LM
authors: Sconfienza
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D012399:Rotation; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000502:physiology*; D014463:Ultrasonography / Q000379:methods*
keywords: Lateral rise; Subacromial space; Ultrasound; Upright row