Glenoid version angle

The glenoid version angle can be determined by either the Friedman method or the scapular blade method. Glenoid version is important in the preoperative assessment for shoulder arthroplasty and can also be useful in the diagnosis of glenoid dysplasia and causes of recurrent glenohumeral instability. 

Measurement

Glenoid version is measured on axial CT or MR scans. Numerous methods have been proposed ⁵. Friedman method has been shown to have better inter-reader reliability and is more user-friendly as scapular and glenoid morphology is less important ^1,3. 

Friedman / scapular line method

A line perpendicular to the Friedman/scapular line is drawn at the level of the glenoid representing neutral glenoid version. Another line is drawn between the anterior and posterior margins of the glenoid and the angle between this line and the neutral glenoid version can be calculated ^1,2,5. 

Scapular body/blade method

This method is the same as the Friedman method but instead of the Friedman/scapular line, the long axis of the scapular blade is used (which, depending on morphology, may or may not intersect the central glenoid fossa) ^3,5. 

Interpretation

The Friedman and scapular body/blade methods are not interchangeable with significant differences in the glenoid version angle calculated in the same shoulder ³.

Different values of normal have been published:

• 0° ± 4° anteversion/retroversion ²

• 4-7° retroversion ⁴