Each year, millions of Americans experience shoulder pain, and one of the most common causes is a rotator cuff tear. This injury occurs when a tendon that connects muscle to bone around the shoulder joint becomes damaged, frayed or completely torn due to repetitive use or sudden trauma. In some cases, nonsurgical treatment can be effective for a full-thickness tear. When conservative treatment is insufficient, arthroscopic rotator cuff repair may be a reliable alternative.
A Respected Shoulder Surgeon at the Forefront of Emerging Treatment Techniques
Christopher C. Schmidt, MD, a board-certified orthopedic shoulder surgeon who practices in Pittsburgh, Pennsylvania, is currently involved in both clinical and mechanical research studies involving arthroscopic rotator cuff tear repair. A leader in his field, Dr. Schmidt serves as Director of the Shoulder and Elbow Fellowship in the Department of Orthopaedic Surgery at the University of Pittsburgh Medical Center (UPMC), where he works with current fellows to train future shoulder surgeons.
Dr. Schmidt performs extensive research in collaboration with a multidisciplinary team of orthopedic surgeons, bioengineers and mechanical engineers, fellows and residents. His biomechanical investigations are conducted through the orthopedic engineering laboratory at UPMC.
The Importance of Locating the Rotator Cable During Arthroscopic Rotator Cuff Repair
Recently, Dr. Schmidt participated in an important study to help his peers develop a reliable method of locating the rotator cable from the bursal side during arthroscopic rotator cuff repair. The location of the rotator cable is significant because it influences suture placement for a stronger rotator cuff repair. Through this study, Dr. Schmidt and his team found that by using the anterior myotendinous junction of the distal supraspinatus muscle as a reference, a surgeon can reliably place sutures medial to the rotator cable to improve repair strength. The abstract of this study is reproduced below.
Location of the Rotator Cable
Zink TR, Davidson AJ, Papadopoulos DV, Schmidt CC
Shoulder and Elbow Laboratory, Department of Orthopaedic Surgery, University Pittsburgh Medical Center
Introduction: The rotator cable (RC) is a semilunar band of collagen fibers within the rotator cuff that is believed to be an important mechanical structure stress shielding the lateral crescent tissue1 (Fig.1a). During rotator cuff repairs, positioning sutures medial to the cable increases pull-out strength, which could result in lowering the re-tear rate2. Further, the RC is reported to act as a suspension bridge preventing pseudoparalysis following a massive tear1. Yet, the RC cannot be located from the bursal side during repair.
The purpose of this anatomic study is to develop a reliable method to locate the rotator cable from the bursal side and determine the presence of a RC avulsion.
Methods: Fifteen fresh-frozen cadaveric specimens (average age 76 ± 18) were dissected down to the level of the rotator cuff and capsuloligamentous tissues. Five cadavers had a rotator cuff tear. The humeral head was cut at the anatomic neck to visualize the RC from the articular surface; the RC was outlined with 2.0 silk suture on a straight needle (Fig.1b). The osteotomy was anatomically reduced and fixed with screws.
The medial-to-lateral rotator cable location was determined by using a reference line that bisected the distal supraspinatus muscle (SS)3. Three distances were measured along the reference line: (A) Myotendinous junction (MTJ)-to-lateral SS insertion, (B) MTJ-to-medial RC, and C) medial RC-to-lateral RC (Fig.2a). The anterior-to-posterior base (APB) of the RC was measured from the upper borders of the subscapularis to the teres minor muscles (Fig.2b).
The ratio of the distance B to A was calculated. Comparison between the groups was performed using the unpaired student t-test.
Results: The rotator cable was visible in 14 specimens from the articular side, while it was not visible from the bursal surface in any of the specimens.
The measurements are summarized in the table. The distances (B, APB) between the intact and tear group did not significantly differ (p > 0.05).
Further, a tear exposing > 47 mm of the greater tuberosity in an anterior-to-posterior direction strongly suggests that RC is ruptured from its anterior, posterior, or both insertions (Fig. 3b,3c).
Conclusion: This study identified that the average distance from medial edge of the RC to the distal SS MTJ was 8.1 ± 5.3 mm (Fig. 3a). In intact rotator cuff tendons, the RC was found on a line that bisects the SS muscle at 30% of its tendon length.
Clinical Relevance: Using the anterior myotendinous junction of the SS as a reference, surgeons can now reliably place sutures medial to the RC to improve repair strength. Exposure of > 47 mm of the greater tuberosity could have implications in defining a massive rotator cuff tear4.
References:1.Burkhart SS, Esch JC, Jolson RS. Arthroscopy. 1993;9(6):611-6. 2.Wieser K, et al. Knee Surg Sports Traumatol Arthrosc 2013;21(7):1587-1592. 3.Mochizuki T, et al. JBJS 2008;90:962-9. 4.Schumaier A,et al. JSES 2020;29(4): 674-68.
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