To The Editor:
I read with great interest the article "Anatomy and Histological
Characteristics of the Spinoglenoid Ligament" (80-A: 1622-1625,
Nov. 1998), by Cummins et al. In the section on clinical relevance,
the authors emphasized that the spinoglenoid ligament may cause
suprascapular nerve entrapment, particularly during overhead athletic
activities.
In our study1, my colleagues and I found that 61 percent (fourteen)
of twenty-three shoulders had a spinoglenoid ligament and, during
cross-body adduction and internal rotation of the glenohumeral joint,
the suprascapular nerve was stretched underneath the spinoglenoid
ligament. Furthermore, we demonstrated that fibrils of the spinoglenoid
ligament interact with the posterior aspect of the capsule. However,
neither this entrapment mechanism nor the interaction with the posterior
aspect of the capsule was mentioned in the study by Cummins et al.
I would be interested in their comments about this issue.
Mehmet Demirhan, M.D.
Department of Orthopaedics and Traumatology,
Istanbul School of Medicine,
34390 Topkapi, Istanbul, Turkey
Dr. Cummins, Dr. Anderson, Dr. Bowen,
Dr. Nuber, and Dr. Roth reply:
In our anatomical study, we identified the spinoglenoid ligament
in ninety (80 percent) of the 112 shoulder specimens. In addition,
three specimens were evaluated histologically. On both gross and
histological inspection, the spinoglenoid ligament originated on
the spine of the scapula and had its major insertion into the periosteum
of the glenoid neck. We agree with the findings of Demirhan et al.1
that the spinoglenoid ligament sends superficial fibers that blend into
the posterior aspect of the capsule. These findings were also reported
by Plancher et al.2 in an abstract presented at the Annual Meeting
of the American Shoulder and Elbow Surgeons in 1997.
Our study was not designed to assess the dynamic relationship
of the spinoglenoid ligament, the suprascapular nerve, and the posterior
part of the shoulder capsule. We thought that the actual physical
dissection of the surrounding tissues in our study may have altered
the relationship of the suprascapular nerve to the spinoglenoid
ligament with the arm in various positions. In addition, we thought
that the use of cadaveric specimens did not accurately reflect the
dynamic relationship that occurs during active shoulder motion.
We believe that the question regarding the relative movement and
tensioning of the ligament and nerve would be best answered with
a dynamic, biomechanical experiment.
We hope that our response to Dr. Demirhan's questions better
clarifies the morphological features of the spinoglenoid ligament.
Craig A. Cummins, M.D.
Kyle Anderson, M.D.
Mark Bowen, M.D.
Gordon Nuber, M.D.
Sanford I. Roth, M.D.
Corresponding author: Craig A. Cummins, M.D.,
Department of Orthopaedic Surgery,
Northwestern University Medical School,
645 North Michigan Avenue, Suite 1058B,
Chicago, Illinois 60611