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Background: The optimal suture configuration for arthroscopic rotator cuff repairs is controversial. "Locked" suture configurations, which use a combination of simple and transverse suture loops, have demonstrated better fixation strength than have traditional simple and horizontal mattress techniques., Purpose: To compare traditional arthroscopic suture configurations to locked arthroscopic configurations in ability to resist gap formation under cyclic loading., Study Design: Controlled laboratory study., Methods: Crescent-shaped defects were created at the infraspinatus tendon insertion in 32 bovine shoulders. Four arthroscopic suture configurations were tested (8 specimens in each group): simple (group 1), horizontal mattress (group 2), locked mattress (group 3), and locked inverted mattress (group 4). A metal corkscrew suture anchor doubly loaded with No. 2 Fiberwire suture was used for the repairs. A cyclic loading protocol with application of forces from 10 to 180 N for a maximum of 2,500 cycles was used. The number of cycles required to form gaps of 5 mm and 10 mm was recorded., Results: The locked mattress configuration (group 3) outperformed all other groups in resisting 5-mm gap formation (P < .0001), requiring a mean of 628 cycles in comparison to 65, 193, and 197 cycles for groups 1, 2, and 4, respectively. Both locked configurations (groups 3 and 4) were superior to traditional simple and horizontal mattress configurations in resisting 10-mm gap formation., Conclusion: The locked mattress suturing technique (group 3) provided the most secure tendon fixation of all arthroscopic configurations tested., Clinical Relevance: The use of locked suture configurations for arthroscopic rotator cuff repairs may enhance tendon fixation and limit gap formation in the early postoperative period.

The purpose of this study was to compare subjects with subacromial impingement and subjects with normal shoulders with respect to muscle activity. Fifteen subjects in each group were studied by means of fine-wire electromyography. The middle deltoid and rotator cuff muscles were evaluated during isotonic scaption from 30 to 120 degrees. Overall, the impingement group demonstrated decreased mean muscle activity in comparison with the group of normal subjects. The magnitude of diminished activity was statistically significantly different (P < .05) during the 30- to 60-degrees arc for the infraspinatus, subscapularis, and middle deltoid muscles; in addition, the infraspinatus muscle demonstrated significantly depressed activity during the 60- to 90-degrees arc. In the impingement group, the supraspinatus and teres minor revealed a diminution of muscle function in comparison with shoulders in the normal group; the difference was not significant. This study demonstrates that muscle activity in subjects with impingement is most notably decreased in the first arc of motion. Also of clinical relevance is the fact that the inferior force vector (from the infraspinatus and subscapularis) is less functional in subjects with impingement than is the superior compressive vector (from the supraspinatus). Thus, humeral head depression during the critical first portion of elevation may be insufficient in people with subacromial impingement.

Thirteen overhand-throwing athletes who failed at least 3 months of physical therapy while restricted from throwing and who demonstrated a positive modified relocation test at 90 degrees, 110 degrees, and/or 120 degrees were clinically and arthroscopically examined. On arthroscopic examination, all patients demonstrated articular surface pathology. Eleven patients had fraying of the undersurface of the rotator cuff, and 10 patients had fraying of the posterosuperior labrum. With 90 degrees shoulder abduction, 8 patients had rotator cuff contact with the posterosuperior labrum. When the shoulder was abducted to 110 degrees, all patients demonstrated such contact. At 120 degrees of abduction, 12 patients revealed contact. The presence or absence of pain during the modified relocation test correlated with the presence or absence of cuff contact with the posterosuperior labrum 79% of the time. Six patients had a positive modified relocation test at all levels of abduction. These patients included 2 with SLAP lesions, 1 with a Bankart lesion, and 1 with a complete tear of the rotator cuff.

The purpose of this study was to compare the effect of increasing loads and doubling speed on the deltoid and rotator cuff muscles during isotonic scapular plane abduction (scaption) with neutral humeral rotation. These muscles were studied in 16 volunteers with asymptomatic shoulders with the use of fine wire electromyography. The addition of load to the arm during scaption caused an increase in electromyographic activity during the first 90 degrees of motion. Furthermore electromyographic activity decreased during the final 30 degrees of motion with each increase in load. Doubling the speed caused an increase in electromyographic activity during the first 60 degrees of motion while causing a decrease in activity in the final 60 degrees. This study demonstrates the response of the rotator cuff and deltoid muscles to varying loads and speeds during the most basic shoulder motion. With the data obtained in this study, rehabilitation exercises and experimental shoulder models can be refined to reflect this more physiologic situation.