Which statement is true regarding the inclination angle and scapular notching?

• A. 155 cut angles led to greater scapular notching
• B. 135 cut angles led to greater scapular notching
• C. 150 cut angles led to greater scapular notching
• D. 165 cut angles led to greater scapular notching

Answer: (A)

The key idea is how the glenosphere’s inclination angle changes the clearance between the humeral component and the inferior scapular neck, which drives scapular notching. Scapular notching happens when the humeral cup contacts the inferior scapular neck during shoulder adduction, causing bone erosion over time. The inclination angle of the glenosphere dictates how far the rim sits relative to the scapular neck in that motion path. At an angle around 155 degrees, the rim alignment places the humeral cup closest to the scapular neck during the adduction arc, increasing the likelihood and amount of repetitive contact. That repeated impingement leads to greater notching compared with other tested angles. If the angle is smaller or larger, the geometry shifts so that contact with the scapular neck during motion is reduced, resulting in less notching.