Not every plane uses canopy splitters. Some planes eject the whole canopy and frame before seat ejection (see: Top Gun).
However, despite my last post, sometimes injury is “designed in”. I was in the process of deciding if I was going to make the Navy my career, and I asked about flying fighters. As I am 6’2" I wondered if they’d take me. They told me that yes, I was within the height limits, but, off the record, if I ever had to eject I would likely lose my knees! While the choice between potentially crippling injury and death is an easy choice, the choice between flying and risking it and not flying was harder. I ultimately chose the ground.
(At least they’d made improvements since the early days-I once sat in an F-86 cockpit, and I couldn’t even see the panel! My knees were up in my chin. It was like I was flying a kiddie car. I don’t think the canopy would have closed, either.)