Contact between the glenoid and the humeral head in abduction, external rotation, and horizontal extension: a new concept of glenoid track.
To date, no anatomic or biomechanical studies have been conducted to clarify what size of a Hill-Sachs lesion needs to be treated. Nine fresh-frozen cadaveric shoulders were tested in a custom device. With the arm in maximum external rotation, horizontal extension, and 0 degrees, 30 degrees, and 60 degrees of abduction, the location of the entire rim of the glenoid was marked on the humeral head using a Kirschner wire. The distance from the contact area to the footprint of the rotator cuff with the arm in 60 degrees of abduction was measured by a digital caliper. With an increase in arm elevation, the glenoid contact shifted from the inferomedial to the superolateral portion of the posterior aspect of the humeral head, creating a zone of contact (glenoid track). The medial margin of the glenoid track was located 18.4 +/- 2.5 mm medial from the footprint, which was equivalent to 84% +/- 14% of the glenoid width. A Hill-Sachs lesion has a risk of engagement and dislocation if it extends medially over the medial margin of the glenoid track.
Yamamoto
Nobuyuki
N
Division of Orthopedic Surgery, Department of Neuro and Locomotor Science, Akita University School of Medicine, Akita, Japan.
Itoi
Eiji
E
Abe
Hidekazu
H
Minagawa
Hiroshi
H
Seki
Nobutoshi
N
Shimada
Yoichi
Y
Okada
Kyoji
K
D000368:Aged; D002102:Cadaver; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000033:anatomy & histology* / Q000502:physiology*; D014057:Tomography, X-Ray Computed