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Scientific Articles:
Tomoyuki Mochizuki, Hiroyuki Sugaya, Mari Uomizu, Kazuhiko Maeda, Keisuke Matsuki, Ichiro Sekiya, Takeshi Muneta, and Keiichi Akita
Humeral Insertion of the Supraspinatus and Infraspinatus. New Anatomical Findings Regarding the Footprint of the Rotator Cuff
J Bone Joint Surg Am 2008; 90: 962-969 [Abstract] [Full text] [PDF]
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[Read Letter to the Editor] Dr. Mochizuki and colleagues respond to Dr. Park
Tomoyuki Mochizuki, MD, Hiroyuki Sugaya, Keiich Akita   (6 November 2008)
[Read Letter to the Editor] Humeral Insertion of the Supraspinatus and Infraspinatus
Maxwell C Park   (19 August 2008)

Dr. Mochizuki and colleagues respond to Dr. Park 6 November 2008
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Tomoyuki Mochizuki, MD,
Research Associate
Section of Orthopaedic Surgery, Division of Cartilage Regeneration, Tokyo Med. and Dent. Univ.,
Hiroyuki Sugaya, Keiich Akita

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Re: Dr. Mochizuki and colleagues respond to Dr. Park

mochizuki.orj{at}tmd.ac.jp Tomoyuki Mochizuki, MD, et al.

We thank Dr. Park for his letter and comments and we appreciate the opportunity to clarify a number of facts described in our paper.

Regarding the border between the supraspinatus and infraspinatus muscles, Dr. Park states that several studies have observed that the oblique fibers of both the supraspinatus and infraspinatus fuse or interdigitate as they converge onto the greater tuberosity (1-4). In our study, we removed the overlying coracohumeral ligament and the loose connective tissues, which enabled us to detect a distinct border between the supraspinatus and infraspinatus and to separate them by precisely tracing the anterior margin of the superior tendinous portion of the infraspinatus. We did not observe interdigitated fibers between the supraspinatus and infraspinatus. We discussed in our paper that these observations which differ from previous reports were attributable to the differences in dissection methods. Recently,we have reconfirmed the validity of our findings by examining histological sections around the insertion of the supraspinatus and infraspinatus. We will report these histological findings in another paper.

Regarding the insertion area of the supraspinatus, Dr. Park proposed that the insertion area of the supraspinatus designated by us represents an anterior supraspinatus-"only" insertion area. This is not correct. We represented the entire area of the supraspinatus insertion. Roh et al reported that the supraspinatus muscle is composed of anterior and posterior muscle bellies (4). We also recognized and described these two separable structures of the supraspinatus in our paper as follows: the supraspinatus tendon was composed of two portions-- the anterior half was long and thick, and the posterior half was short and thin (Fig. 3, C); most of the muscle fibers of the supraspinatus, especially those of its superficial layer, ran anterolaterally toward the anterior tendinous portion, while the rest of the fibers from the deep layer ran laterally toward the medial margin of the highest impression margin on the greater tuberosity (Figs. 1; 2, A; and 3, A).

Most of the supraspinatus muscle fibers which run anterolaterally and converge at the anterior tendinous portion [which correspond to the anterior supraspinatus described by Roh et al.(4)] were inserted into the anterior part of the triangular footprint of the supraspinatus, and the rest of the muscle fibers corresponding to the posterior infraspinatus by Roh et al.(4) were inserted into the medial margin of the triangular shaped footprint of the supraspinatus.

References

1. Clark JM, Harryman II DT. Tendons, ligaments, and capsule of the rotator cuff. Gross and microscopic anatomy. J Bone Joint Surg 1992;74A:713-25.

2. Miller SL, Gladstone JN, Cleeman E, et al. Anatomy of the posterior rotator interval: implications for cuff mobilization. Clin Orthop 2003;408:152-6.

3. Minagawa H, Itoi E, Konno N, et al. Humeral Attachment of the Supraspinatus and Infraspinatus Tendons: An Anatomic Study. Arthroscopy 1998;14:302-6.

4. Roh MS, Wang VM, April EW, et al. Anterior and posterior musculotendinous anatomy of the supraspinatus. J Shoulder Elbow Surg 2000;9:436-40.
Humeral Insertion of the Supraspinatus and Infraspinatus 19 August 2008
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Maxwell C Park,
MD
Southern California Permanente Medical Group, Woodland Hills, CA

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Re: Humeral Insertion of the Supraspinatus and Infraspinatus

mcp16{at}columbia.edu Maxwell C Park

To the Editor;

I read with interest the study by Mochizuki et al, “Humeral Insertion of the Supraspinatus and Infraspinatus: New Anatomical Findings Regarding the Footprint of the Rotator Cuff”.This study attempts to redefine the characterization of how the supraspinatus and infraspinatus insert onto the greater tuberosity. This has obvious implications when attempting to repair a torn rotator cuff tendon involving these muscles.

Several studies have observed how the oblique fibers from both supraspinatus and infraspinatus “fuse” or “interdigitate” as they converge onto the greater tuberosity(1-4). I agree that Figures 5 and 6 may show the supraspinatus insertion area, but perhaps this should be qualified as an anterior supraspinatus-"only" insertion area; this does not account for the fact that the supraspinatus and infraspinatus interdigitate and obligatorily share insertion site area on the greater tuberosity. At a minimum, this is what is clinically observed; to characterize the insertions as discrete and separate may not be helpful.

The authors should be commended for delineating the supraspinatus anatomy. The qualification described above should be pointed out, however, as the description of a discrete triangular insertion area for the supraspinatus does not account for the aspect of the tendon that is shared with the infraspinatus on the greater tuberosity. This has been observed in the references cited(1-4), and should be a reminder to surgeons as they attempt to restore normal anatomy during rotator cuff repair.

The author did not receive any outside funding or grants in support of his research for or preparation of this work. Neither he nor a member of his immediate family received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the author, or a member of his immediate family, is affiliated or associated.

1. Clark JM, Harryman II DT. Tendons, ligaments, and capsule of the rotator cuff. Gross and microscopic anatomy. J Bone Joint Surg 1992;74A:713-25. 2. Miller SL, Gladstone JN, Cleeman E, et al. Anatomy of the posterior rotator interval: implications for cuff mobilization. Clin Orthop 2003;408:152-6. 3. Minagawa H, Itoi E, Konno N, et al. Humeral Attachment of the Supraspinatus and Infraspinatus Tendons: An Anatomic Study. Arthroscopy 1998;14:302-6. 4. Roh MS, Wang VM, April EW, et al. Anterior and posterior musculotendinous anatomy of the supraspinatus. J Shoulder Elbow Surg 2000;9:436-40.