The purpose of this study was to reveal the prevalence of the so-called inverted-pear glenoid with or without associated bony fragment. According to previous literature, a majority of the inverted-pear glenoid, which is defined as more than 25% to 27% defect of the glenoid width, is not associated with a bony fragment and, therefore, open bone grafting is indicated. However. Sugaya introduced arthroscopic bony reconstruction in patients with a large glenoid defect associated with a bony fragment and reported excellent outcomes. A consecutive series of 121 shoulders, including 97 males and 24 females with an average age of 24 years (range,13-54), were evaluated using 3DCT with the humeral head-eliminated preoperatively. Bone loss was determined as a ratio of defect width against the diameter of the assumed circle based on the inferior portion of each glenoid. The prevalence of the inverted-pear glenoid was investigated when the defect rate was set at more than 25% and more than 30% defect. There were 58 bony Bankarts and 55 erosions with an average defect rate of 21.6% (range,9.1-43.8) and 11.4% (range,2.7-27.8), respectively. Nine-teen glenoids (15.7%) were measured as more than 25% defect with an average defect rate of 30.2% (range,25.0-43.8). A bony fragment was confirmed in 18 out of 19 shoulders (94.7%) in this group. On the other hand,9 glenoids (7.4%) were measured as more than 30% defect with an average defect rate of 35.6% (range,30.6-43.8). A bony fragment was confirmed in all shoulders in this group. In conclusion, a majority of shoulders with a large glenoid defect are associated with a bony fragment as evaluated by 3DCT.
