Biconcave Glenoids Show Three Differently Orientated Posterior Erosion Patterns
These authors assessed glenoid morphology and evaluated the influence of acromial orientation in posterior glenoid erosion patterns in 68 patients (average age 64, 49 males, 19 females) planned to have reverse total shoulder arthroplasty.
Using a reference 90 degrees as straight posterior and 0 degrees as straight superior, the average direction of glenoid erosion was 85.9 degrees with a large standard deviation of 22 degrees.
The eroded part of the glenoid averaged 52% (±12%) of the glenoid surface.
Glenoid version was 73±7° (90° was used to describe a glenoid with no version)
Premorbid glenoid retroversion averaged 81±8°)
Glenoid inclination averaged 85.4° (± 6.6°)
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39 were classified as posterior central erosion (87°). These had the greatest depth of erosion (7mm)
12 as posterior inferior (116 degrees) and
17 as posterior superior (62 degrees)
No significant differences between the observed erosion patterns or any relevant correlations were found with respect to the orientation of the acromion.
Comment: This is a detailed analysis of the glenoid pathoanatomy found in a series of biconcave glenoids. The authors point out that the glenoid erosion in a biconcave glenoid is not always straight posterior. Therefore, "posterior augments" may not always fit the pattern of bone loss.
