title: Effects of asymptomatic rotator cuff pathology on in vivo shoulder motion and clinical outcomes.
abstract: BACKGROUND
  The incidence of asymptomatic rotator cuff tears has been reported to range from 15% to 39%, but the influence of asymptomatic rotator cuff pathology on shoulder function is not well understood. This study assessed the effects of asymptomatic rotator cuff pathology on shoulder kinematics, strength, and patient-reported outcomes.
  
  
  METHODS
  A clinical ultrasound examination was performed in 46 asymptomatic volunteers (age: 60.3 ± 7.5 years) with normal shoulder function to document the condition of their rotator cuff. The ultrasound imaging identified the participants as healthy (n = 14) or pathologic (n = 32). Shoulder motion was measured with a biplane x-ray imaging system, strength was assessed with a Biodex (Biodex Medical Systems, Inc., Shirley, NY, USA), and patient-reported outcomes were assessed using the Western Ontario Rotator Cuff Index and visual analog scale pain scores.
  
  
  RESULTS
  Compared with healthy volunteers, those with rotator cuff pathology had significantly less abduction (P = .050) and elevation (P = .041) strength, their humerus was positioned more inferiorly on the glenoid (P = .018), and the glenohumeral contact path length was longer (P = .007). No significant differences were detected in the Western Ontario Rotator Cuff Index, visual analog scale, range of motion, or acromiohumeral distance.
  
  
  CONCLUSIONS
  The differences observed between the healthy volunteers and those with asymptomatic rotator cuff pathology lend insight into the changes in joint mechanics, shoulder strength, and conventional clinical outcomes associated with the early stages of rotator cuff pathology. Furthermore, these findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology.
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, MI, USA. Electronic address: tbaumer1@hfhs.org.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Baumer
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Jack
authors.initials: J
authors.lastname: Dischler
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Veronica
authors.initials: V
authors.lastname: Mende
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Zauel
authors.affiliation: Department of Radiology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Marnix
authors.initials: M
authors.lastname: van Holsbeeck
authors.affiliation: Department of Radiology, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Siegal
authors.affiliation: Department of Public Health Sciences, Henry Ford Health System, Detroit, MI, USA.
authors.forename: George
authors.initials: G
authors.lastname: Divine
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Vasilios
authors.initials: V
authors.lastname: Moutzouros
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, MI, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bey
mesh_terms: D000328:Adult; D000368:Aged; D058070:Asymptomatic Diseases; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D015994:Incidence; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000070636:Rotator Cuff Injuries / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D012785:Shoulder Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography; D014481:United States / Q000453:epidemiology
keywords: Shoulder; asymptomatic; biomechanics; clinical outcomes; motion analysis; rotator cuff