In the Berserk manga, given the enormous amount of chapters dealing with Guts' over-sized sword, the Dragonslayer, I didn't try finding a pic that clearly shows the sword hanging slantingly along his dorsum. Neither did I notice the following issue before completing all the available episodes.
I'm intrigued by how exactly Guts was always able to wield Dragonslayer without at first having any difficulty from the hooks holding it, unhinges it to be more precise to say. If we assume having his arm fully stretched upward and trying to displace Dragonslayer from its stationary position, then prima facie the distance between his grip (not of sword's) and shoulders cannot be greater than or equal to the length of the blade of the Dragonslayer.
It is this impracticability that made me to request here, a picture of Guts along with the Dragonslayer featuring his dorsum without any cape, so as to understand the truth. While a picture will speak the answer by itself, a context around it or without the picture itself may help too.
Edit: On a side note, these pictures of Guts somewhat shows the hinge which holds off Guts' sword. But I can't fathom how then he could use the sword instantly when the sword needs to be unhooked every time to slay the enemy.
(Click image to enlarge it)