2015 ISAKOS Biennial Congress ePoster #2310

A New Diagnostic Method for the Diagnosis of Multiple Directional Shoulder Instability

Kyoung-Jin Park, MD, PhD, Cheongju, Chungbuk KOREA, REPUBLIC OF
Hyun-Chul Shon, MD, Cheongju, Chungbuk KOREA, REPUBLIC OF
Byung-Ki Cho, MD, Cheongju, Chungbuk KOREA, REPUBLIC OF
Ji-Kang Park, MD, Cheongju, Chungbuk KOREA, REPUBLIC OF
Ho Seung Jeong, MD, Cheong-Ju KOREA, REPUBLIC OF
Chae-Ouk Lim, MD, Cheong-Ju KOREA, REPUBLIC OF

Department of Orthopaedic Surgery, College of Medicine, Chungbuk National University , Cheongju, Chungbuk, KOREA

FDA Status Not Applicable

Summary: For the clinical diagnosis of MDI, the Labro-capsular distance can easily and quickly be measured and used as an effective diagnostic method.

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Abstract:

Objective

We compared the differences in capsular volumes between the patient group of multidirectional shoulder instability and the control group. We tried to find a new diagnostic method which can be easily and quickly done and be used as an effective diagnosis tool.

Subjects & Methods: All patients who had been diagnosed with multidirectional instability of the shoulder(n = 43) after being assessed with shoulder MRA during 6 years from 2007 to 2012 were reviewed. A total of 43 patients without shoulder instability were also selected for the control group. The shoulder MRA of all groups were randomly mixed, and two orthopedic surgeon reviewers recorded the measures of capsular lengths and sizes. The MRI sequences included axial, sagittal, and coronal images from which the measures were obtained. First, the MRA axial images took measurements of capsular sizes. The maximum capsular distension was measured along the several specified axial images. A ratio (axial b/a) for the two groups was determined by dividing the distance from the anterior aspect of the lesser tuberosity to the posterior aspect of the humeral head, along the same line as the maximal posterior capsular measurement, by the distance from the anterior aspect of the lesser tuberosity to the most posterior aspect of the capsule. Secondly, the MRA sagittal images took measurements of the capsular sizes and distensions. The posterior capsular distension was measured on specific sagittal cuts, as well as the cut with the largest posterior fluid pocket. A ratio (sagittal b/a) for the two groups was determined by calculating the distances from the most posterior aspect of coracoid process through humeral head to the most posterior aspect of joint capsule (saggital b) and from the most posterior aspect of coracoid to the most posterior aspect of humeral head (saggital a), and by dividing the former by the latter. Additionally, from the sagittal cut with the largest amount of contrast material, the total cross-sectional area (CSA) of the capsular area and the humeral head area were obtained. A ratio (CSA b/a) of the two groups was determined by dividing the cross sectional area by the humeral head area. Finally, the MRA coronal images took measurements of capsular sizes and distensions. The maximum capsular distension was measured along the several specified coronal images. The distance was determined by measuring the length from the most convex point of glenoid inferior labrum to the lowest point of the capsule. This study named the above measured distance as ‘L-C distance’ (Labro-capsular distance)

Results

The following measurements of distances were increased in the patient group of multidirectional shoulder instability with the comparison to the control group: Axial b/a (average: 1.25) versus the control group (average: 1.06), (p<0.001); sagittal b/a (average: 1.25) versus the control group (average: 1.06), (p<0.001); CSA b/a (average: 2.04) versus the control group (average: 1.34), (p<0.001); and L-C distance (average: 18.83mm) versus the control group (average: 10.58mm),(p<0.001). If the L-C distance is greater than 15.51mm, it can be suspected of multidirectional shoulder instability due to the highest sensitivity and specificity.

Conclusion

For the clinical diagnosis of MDI, the L-C distance can easily and quickly be measured and used as an effective diagnostic method.