Optimal shoulder immobilization postures following surgical repair of rotator cuff tears: a simulation analysis.
This is an important article. It shows that the repair of rotator cuff tear gaps puts the repair under excess tension unless the arm is immobilized in substantial elevation.
The authors point out that there is a high incidence of retear following surgical repair of rotator cuff tears and that there is no consensus on the optimal position for postoperative shoulder immobilization.
They used a model of the shoulder to simulate postoperative immobilization of full thickness rotator cuff tears involving the supraspinatus only and the supraspinatus concomitantly with the infraspinatus or subscapularis. They sought immobilization postures that minimized the stresses in the repaired tendons and the angle of humerus elevation.
Rotator cuff tears were simulated by reducing the length of the involved tendons (introducing a tendon gap that represented the loss of tendon due to the tear itself and also tendon removal during surgery). Tear repair was simulated by assuming that the musculotendinous units were stretched, such that the tendon insertions on the humeral head were restored. In their model, any tension generated in the rotator cuff was assumed to be due to passive tension from stretching of the musculotendinous units.
They simulated a full-thickness supraspinatus tears, full-thickness supraspinatus and infraspinatus tears, and full-thickness supraspinatus and subscapularis tears. Tears of varying severity were simulated by introducing gap lengths of 0-20 mm in 5 mm increments. Their model then determined the position in which the stresses in the repaired tendons were minimized, the elevation of the humerus was minimized, the stresses in the uninjured tendons were maintained below 300 Ncm−2 to ensure integrity of these tendons, and the position of the humerus was within anatomical limits.
For isolated supraspinatus tears, the ideal elevation angle increased from 61° to 109° as tear length increased from 0 to 20 mm, while the required plane of elevation moved from 13° to 37° anterior to the coronal plane (i.e. close to the plane of the scapula).
For supraspinatus and infraspinatus tears, the ideal elevation angle increased from 61° to 106° as tear severity was increased. For gap lengths of 15 and 20 mm, the ideal plane of elevation was closer to the coronal plane.
For supraspinatus and subscapularis tears, the ideal plane of elevation moved from 28° to 77° anterior to the coronal plane as tear length increased from 0 to 15 mm, while the optimal elevation angle varied between 58° and 70° and the required internal rotation varied between 35° and 60°. The optimal postures were the same for gap lengths of 15 and 20 mm.
The stresses in the repaired tendons were reduced from 29% to 90%. by immobilization with the arm elevated from 58° to 109°, depending on the tear length and the muscles involved.
The authors point out that there is a high incidence of retear following surgical repair of rotator cuff tears and that there is no consensus on the optimal position for postoperative shoulder immobilization.
They used a model of the shoulder to simulate postoperative immobilization of full thickness rotator cuff tears involving the supraspinatus only and the supraspinatus concomitantly with the infraspinatus or subscapularis. They sought immobilization postures that minimized the stresses in the repaired tendons and the angle of humerus elevation.
Rotator cuff tears were simulated by reducing the length of the involved tendons (introducing a tendon gap that represented the loss of tendon due to the tear itself and also tendon removal during surgery). Tear repair was simulated by assuming that the musculotendinous units were stretched, such that the tendon insertions on the humeral head were restored. In their model, any tension generated in the rotator cuff was assumed to be due to passive tension from stretching of the musculotendinous units.
They simulated a full-thickness supraspinatus tears, full-thickness supraspinatus and infraspinatus tears, and full-thickness supraspinatus and subscapularis tears. Tears of varying severity were simulated by introducing gap lengths of 0-20 mm in 5 mm increments. Their model then determined the position in which the stresses in the repaired tendons were minimized, the elevation of the humerus was minimized, the stresses in the uninjured tendons were maintained below 300 Ncm−2 to ensure integrity of these tendons, and the position of the humerus was within anatomical limits.
Importantly their results showed that post-operative immobilization in a standard sling applied excessive loads to the repair.
For supraspinatus and infraspinatus tears, the ideal elevation angle increased from 61° to 106° as tear severity was increased. For gap lengths of 15 and 20 mm, the ideal plane of elevation was closer to the coronal plane.
For supraspinatus and subscapularis tears, the ideal plane of elevation moved from 28° to 77° anterior to the coronal plane as tear length increased from 0 to 15 mm, while the optimal elevation angle varied between 58° and 70° and the required internal rotation varied between 35° and 60°. The optimal postures were the same for gap lengths of 15 and 20 mm.
The stresses in the repaired tendons were reduced from 29% to 90%. by immobilization with the arm elevated from 58° to 109°, depending on the tear length and the muscles involved.
What is not examined in this model is (1) the effectiveness of immobilization in abduction on tendon repair loads in vivo (i.e. does the patient contract their cuff muscles when moving around - in fact do they use their cuff muscles to position the abduction device comfortably?), (2) what happens when the device is removed for hygiene or dressing?, (3) how long should the device be worn? and (4) what happens when the device is finally removed?
The bottom line, however, is that repairs of cuff tendon gaps result in increased tension on the repair, and, as we've shown previously, this tension is borne by a small number of sutures placing the repair at risk from suture tension overload.
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You may be interested in some of our most visited web pages including:shoulder arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'
