In the VIP system, which pair of legs overhang the glenoid surface?

• A. Anterior-Superior & Posterior-Inferior
• B. Posterior-Superior & Anterior-Inferior
• C. Anterior-Inferior & Posterior-Inferior
• D. Anterior-Superior & Anterior-Inferior

Answer: (D)

The design principle here is securing the glenoid component by maximizing purchase where the bone is strongest and where the rim supports most of the load. In the VIP system, the two fixation legs extend beyond the glenoid surface on the anterior side, with one positioned at the superior edge and the other at the inferior edge. This anterior overhang provides solid cortical bone contact, helps resist the shear and tilting forces from the humeral head, and helps distribute load more evenly across the glenoid rim. It also preserves the posterior rim and reduces the risk of posterior impingement or instability that might occur with a posteriorly placed or misaligned leg set. So the pair that overhangs the glenoid surface are the anterior-superior and anterior-inferior legs.