Chosen Solution

I know it is possible to replace the left hinge by taking the lcd display off from the frame but! and here is the big but. Would I be able to cut the left hinge and reconnect it to a new one where the hinge is not broken? In theory it should be possible but I just don’t have the guts to try it

You can replace either hinge after removing the display assembly following this guide MacBook Pro 15" Retina Display Early 2013 Display Assembly Replacement. The tricky part is the hinges are hollow with wires running through them. You need to disconnect the wires at the connectors within the lid. And NO! You can’t cut or alter the hinges or the wires! All you’ll do is damage the parts. Review this MacBook Pro Retina Display Teardown it will visually show you what’s involved. Here’s the parts: Retina MacBook Pro - Left Hinge & LVDS Cable, Apple P/N 818-2882Retina MacBook Pro - Right Hinge & Antenna/iSight Cable, Apple P/N 818-2882