title: A new screening method for multidirectional shoulder instability on magnetic resonance arthrography: labro-capsular distance.
abstract: OBJECTIVE
  To compare the capsular dimension as measured on magnetic resonance arthrography (MRA) between patients with multidirectional instability (MDI) of the shoulder and control subjects without instability. Ultimately, we aimed to develop an easy and reliable new screening method to assess MDI of the shoulder using MRA.
  
  
  METHODS
  MRA images of patients with MDI of the shoulder (n = 25) during a 6-year period (February 2010 to May 2015) were retrospectively reviewed. A control group (n = 26) without instability was also identified. The capsular area was measured using a new screening method we termed labro-capsular (LC) distance. MRA images of the two groups were randomly mixed, and two orthopedic surgeon reviewers recorded anterior, posterior, and inferior LC distance measurements on axial and coronal images using a mid-glenoid cut.
  
  
  RESULTS
  The inferior LC distance increased significantly in the patient group versus control group (P < 0.001), but there were no statistically significant differences in the anterior (P = 0.1165) and posterior (P = 0.5229) LC distances. An inferior LC distance >16.88 mm is most suggestive of MDI of the shoulder because of its high sensitivity (76 %) and specificity (96 %).
  
  
  CONCLUSIONS
  The inferior LC distance can be easily and quickly measured and used as an effective clinical screening method for atraumatic MDI of the shoulder.
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Chungbuk National University, 62, Gaesin-Dong, Cheongju, Chungbuk, 360-711, Republic of Korea.
authors.forename: Chae-Ouk
authors.initials: CO
authors.lastname: Lim
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Chungbuk National University, 62, Gaesin-Dong, Cheongju, Chungbuk, 360-711, Republic of Korea. oslion@chungbuk.ac.kr.
authors.forename: Kyoung-Jin
authors.initials: KJ
authors.lastname: Park
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Chungbuk National University, 62, Gaesin-Dong, Cheongju, Chungbuk, 360-711, Republic of Korea.
authors.forename: Byung-Ki
authors.initials: BK
authors.lastname: Cho
authors.affiliation: Department of Orthopaedic Surgery, College of Medicine, Chungbuk National University, 62, Gaesin-Dong, Cheongju, Chungbuk, 360-711, Republic of Korea.
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Kim
authors.affiliation: Department of Diagnostic Radiology, College of Medicine, Catholic Kwandong University, Incheon, Republic of Korea.
authors.forename: Kyung-Ah
authors.initials: KA
authors.lastname: Chun
mesh_terms: D000293:Adolescent; D000328:Adult; D001175:Arthrography; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D055815:Young Adult
keywords: Capsular redundancy; Labro-capsular distance; Magnetic resonance arthrography; Multidirectional shoulder instability