title: Subacromial volume and rotator cuff tears: Does an association exist?
abstract: BACKGROUND
  Rotator cuff pathology occurs commonly and its cause is likely multifocal in origin. The development and progression of rotator cuff injury, especially in relation to extrinsic shoulder compression, remain unclear. Traditionally, certain acromial morphologies have been thought to contribute to rotator cuff injury by physically decreasing the subacromial space. The relationship between subacromial space volume and rotator cuff tears (RCT) has, however, never been experimentally confirmed. In this study, we retrospectively compared a control patient population to patients with partial or complete RCTs in an attempt to quantify the relationship between subacromial volume and tear type.
  
  
  METHODS
  We retrospectively identified a total of 46 eligible patients who each had shoulder magnetic resonance imaging (MRI) performed from January to December of 2008. These patients were stratified into control, partial RCT, and full-thickness RCT groups. Subacromial volume was estimated for each patient by averaging five sequential MRI measurements of subacromial cross-sectional areas. These volumes were compared between control and experimental groups using the Student's t-test.
  
  
  RESULTS
  With the numbers available, there was no statistically significant difference in subacromial volume measured between: the control group and patients diagnosed partial RCT (P > 0.339), the control group and patients with complete RCTs (P > 0.431).
  
  
  CONCLUSIONS
  We conclude that subacromial volumes cannot be reliably used to predict RCT type.
authors.affiliation: Department of Orthopedic Surgery, University of Southern California, Los Angeles, California, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Yi
authors.affiliation: Department of Orthopedic Surgery, University of Southern California, Los Angeles, California, USA.
authors.forename: Ioannis A
authors.initials: IA
authors.lastname: Avramis
authors.affiliation: Department of Orthopedic Surgery, University of Southern California, Los Angeles, California, USA.
authors.forename: Evan H
authors.initials: EH
authors.lastname: Argintar
authors.affiliation: Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: White
authors.affiliation: Department of Orthopedic Surgery, University of Southern California, Los Angeles, California, USA.
authors.forename: Diego C
authors.initials: DC
authors.lastname: Villacis
authors.affiliation: Department of Orthopedic Surgery, University of Southern California, Los Angeles, California, USA.
authors.forename: George F Rick
authors.initials: GF
authors.lastname: Hatch Iii
keywords: Magnetic resonance imaging; Shoulder; magnetic resonance imaging; rotator cuff; rotator cuff tear; subacromial volume