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The “bare spot” of the glenoid cavity has recently been described as
a constant reference point to quantify the amount of bone loss of the
inferior portion of the glenoid cavity. In shoulder surgery this spot
should help the surgeon determining the width of the inferior portion
of the glenoid cavity arthroscopically. The aim of this study was to
determine the localisation of the bare spot within the glenoid cavity
and to prove its usefulness in shoulder surgery by means of a
macroscopic study using embalmed glenohumeral joints (N=20; 12
left, 8 right). Each glenoid cavity was photographed and transferred to a customary AutoCAD software programme. The bare spot was
marked and the mean distances between the center of the bare spot
and the inferior (a), anterior (b1) and posterior (b2) inner margins of
the glenoid labrum as well as its relationship (c) to the mid-point of a
virtual circle formed by the inferior portion of the glenoid cavity were
measured (mean values for: a=9.70, b1=10.88, b2=13.71, c=3.2
mm). In most cases, the bare spot showed a significantly excentric
position within the inferior part of the glenoid cavity (p<0.05). Due to
the great variability of the shape of the glenoid cavity, an inferior
circle according to previous descriptions could be only observed in
half of the specimens. Following the results of our study the bare
spot seems to be an insecure landmark for the determination of the
center of the inferior portion of the glenoid cavity, although it has a
constant appearance and is probably expressed as the effect of
cartilaginous distribution due to dynamic shoulder activity.