Evaluation of Inferior Capsular Laxity in Patients with Atraumatic Multidirectional Shoulder Instability with Magnetic Resonance Arthrography
- Author:
Kyoung Jin PARK
1
;
Ho Seung JEONG
;
Ji Kang PARK
;
Jung Kwon CHA
;
Sang Woo KANG
Author Information
- Publication Type:Original Article
- Keywords: Multidirectional shoulder instability; MDI; Magnetic resonance arthrography; MRA; Capsular redundancy; Inferior instability
- MeSH: Arthrography; Female; Humans; Male; Mass Screening; Methods; Orthopedics; Retrospective Studies; Sensitivity and Specificity; Shoulder
- From:Korean Journal of Radiology 2019;20(6):931-938
- CountryRepublic of Korea
- Language:English
- Abstract: OBJECTIVE: To compare inferior capsular redundancy by using magnetic resonance arthrography (MRA) images in patients with multidirectional instability (MDI) of the shoulder and control subjects without instability and thereby develop a screening method to identify the presence of shoulder MDI. MATERIALS AND METHODS: The MRA images of patients with MDI of the shoulder (n = 65, 57 men, 8 women; mean age, 24.5 years; age range, 18–42 years) treated over an eight-year period were retrospectively reviewed; a control group (n = 65, 57 men, 8 women; mean age, 27.4 years; age range, 18–45 years) without instability was also selected. The inferior capsular redundancy was measured using a new method we named the glenocapsular (GC) ratio method. MRA images of both groups were randomly mixed together, and two orthopedic surgeon reviewers measured the cross-sectional areas (CSAs) and sagittal capsule-head ratios on oblique sagittal images, as well as the axial capsule-head ratios on axial images and GC ratios on oblique coronal images. RESULTS: The CSAs and GC ratios were significantly higher in patients than in controls (both, p < 0.001); however, the sagittal capsule-head ratios and axial capsule-head ratios were not significantly different (p = 0.317, p = 0.053, respectively). In addition, GC ratios determined the presence of MDI more sensitively and specifically than did CSAs. A GC ratio of > 1.42 was found to be most suggestive of MDI of the shoulder, owing to its high sensitivity (92.3%) and specificity (89.2%). CONCLUSION: GC ratio can be easily measured and used to accurately screen for MDI of the shoulder.
