Yusuke Kawano1, Noboru Matsumura2, Akihiko Murai3, Mitsunori Tada3, Morio Matsumoto1, Masaya Nakamura1, Takeo Nagura4. 1. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan. 2. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan. Electronic address: noboru18@gmail.com. 3. Digital Human Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan. 4. Department of Clinical Biomechanics, Keio University School of Medicine, Tokyo, Japan.
Abstract
PURPOSE: To evaluate the distance and position of humeral head translation during glenohumeral motion and to investigate the function of the rotator cuff in glenohumeral translation. METHODS: Using 9 cadavers, glenohumeral translation during passive pendulum motion was tracked by an optical motion capture system. Tension was applied to 5 compartments of the rotator cuff muscles, and 7 different conditions of rotator cuff dysfunction were sequentially simulated. Three-dimensional glenohumeral structure was reconstructed from the computed tomography images of the specimens, and the distance and position of glenohumeral translation were compared among the conditions. RESULTS: The average radius of glenohumeral translation was 10.6 ± 4.3 mm when static loading was applied to all rotator cuff muscles. The radius increased significantly in the models without traction force on the supraspinatus and total subscapularis tendons (P = .030). The position of the translation center did not change in the mediolateral direction (P = .587) and in the anteroposterior direction (P = .138), but it moved significantly superiorly in the models without supraspinatus and infraspinatus loading (P = .011) and in those without supraspinatus, infraspinatus, and teres minor loading (P < .001). CONCLUSIONS: The distance and position of humeral head translation during glenohumeral motion changed with rotator cuff deficiency. The present study indicated that the subscapularis plays an important role in maintaining the central position of the humeral head, and that the infraspinatus acts as a major depressor of the humeral head during shoulder motion. CLINICAL RELEVANCE: The results of this study suggest that extension of a tear into the subscapularis should be avoided to maintain the centering function of the glenohumeral joint in cases with rotator cuff tear.
PURPOSE: To evaluate the distance and position of humeral head translation during glenohumeral motion and to investigate the function of the rotator cuff in glenohumeral translation. METHODS: Using 9 cadavers, glenohumeral translation during passive pendulum motion was tracked by an optical motion capture system. Tension was applied to 5 compartments of the rotator cuff muscles, and 7 different conditions of rotator cuff dysfunction were sequentially simulated. Three-dimensional glenohumeral structure was reconstructed from the computed tomography images of the specimens, and the distance and position of glenohumeral translation were compared among the conditions. RESULTS: The average radius of glenohumeral translation was 10.6 ± 4.3 mm when static loading was applied to all rotator cuff muscles. The radius increased significantly in the models without traction force on the supraspinatus and total subscapularis tendons (P = .030). The position of the translation center did not change in the mediolateral direction (P = .587) and in the anteroposterior direction (P = .138), but it moved significantly superiorly in the models without supraspinatus and infraspinatus loading (P = .011) and in those without supraspinatus, infraspinatus, and teres minor loading (P < .001). CONCLUSIONS: The distance and position of humeral head translation during glenohumeral motion changed with rotator cuff deficiency. The present study indicated that the subscapularis plays an important role in maintaining the central position of the humeral head, and that the infraspinatus acts as a major depressor of the humeral head during shoulder motion. CLINICAL RELEVANCE: The results of this study suggest that extension of a tear into the subscapularis should be avoided to maintain the centering function of the glenohumeral joint in cases with rotator cuff tear.
Authors: Stefan Bauer; Taro Okamoto; Stephanie M Babic; Jonathon C Coward; Charline M P L Coron; William G Blakeney Journal: EFORT Open Rev Date: 2022-03-17