How Important Is the Anterior Rotator Cuff Cable?: Commentary on an article by Mena M. Mesiha, MD, et al.: “The Biomechanical Relevance of Anterior Rotator Cuff Cable Tears in a Cadaveric Shoulder Model”

第一作者：Xavier A. Duralde

2013-11-20 　　我要说

There is a growing body of clinical evidence that indicates that patients can maintain relatively normal shoulder function despite a tear in the rotator cuff. This has been proven with magnetic resonance imaging studies of asymptomatic patients¹ as well as clinical studies revealing unsuspected disruptions following rotator cuff repair². Indeed, clinical series in which only partial rotator cuff repairs were performed have yielded good results despite the fact that there was a known deficiency in the rotator cuff following surgery^3,4. In all of these scenarios, patients are often minimally symptomatic and maintain good shoulder function with minimal pain. There is poor correlation between cuff tear size and the degree of either pain or functional restrictions noted by the patient. This would tend to indicate that there are factors intrinsic to different types of cuff tears that lead to varying degrees of symptoms.

Burkhart et al. were the first to propose a theoretical basis for this phenomenon with the “suspension bridge” model⁵. They postulated that, if intact portions of the cuff anteriorly and posteriorly can “couple” in a balanced fashion, a physiologic force vector is created and the shoulder will function better than shoulders in which this balance is not achieved. Their anatomic studies emphasized the importance of the rotator cuff cable and crescent as a means of transferring force from the rotator cuff to the greater tuberosity despite a loss of integrity in the cuff. However, until now, no biomechanical study had been performed to verify the importance of the anterior rotator cuff cable. This paper, “The Biomechanical Relevance of Anterior Rotator Cuff Cable Tears in a Cadaveric Shoulder Model,” demonstrates the biomechanical support for the “suspension bridge” model and the critical importance of the anterior rotator cuff cable. In this study, Dr. Mesiha and colleagues compared equivalently sized laboratory-created rotator cuff tears in matched cadaver shoulders. In half of the cadavers, the anterior rotator cuff cable (the most anterior 8 to 12 mm of the supraspinatus tendon just posterior to the bicipital groove) was included in the tear and, in the other half, the cable was left intact. Specimens were cyclically loaded and were tested for gap distance, stiffness, and regional strain of the supraspinatus. In the specimens without an intact anterior rotator cuff cable, gap formation was greater, stiffness was less, and regional strains were increased in magnitude and altered in distribution compared with the specimens with an intact cable. These findings indicate that the force of the supraspinatus muscle is more normally transmitted to the greater tuberosity if the anterior cable is intact.

It is fortunate that the majority of rotator cuff tears identified at the time of surgery originate posterior to the rotator cuff cable⁶, and this may explain why many rotator cuff tears are minimally symptomatic. From a clinical standpoint, it is critical for surgeons to understand the importance of this most anterior 8 to 12-mm slip of the supraspinatus tendon.

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