I am not a qualified accident investigator
A skewer snapping sounds more like a result than a cause. The skewer holds the wheel in place, and breaking is a consequence of some other event.
I would get an impartial person to inspect the bike closely, and document what they find. Don't fix anything though.
- front wheel spoke trueness and dents/bent spokes
- fork alignment, has it been bent.
- Brakes - do they tell you anything ?
I'd also get a very clear macro photograph of each end of the broken skewer to see if it shows anything, like "tide marks" or if its all one clean break.
Were there witnesses at all? Who called the ambulance? Did they see what happened? Are there any traffic cameras or "public safety" cameras in that spot ?
Looking at the photo, the skewer has clearly parted. At first I thought "that's a lot of skewer sticking out of the hub" then realised that the wheel is not in the fork, so the extra length visible is what would be passing through the fork dropouts on both sides.
The tip of the skewer is interesting - looking at the break I can see:
- Red lines show the edge of the thread, both the crest and valley
- Green line shows the metal that is inside the thread at one point on the circumference
- The inner Red circle is the core and is solid metal
We can see a clear delineation between the Blue shaded area and the part closer to the thread. I would guess that the Blue-shaded area is rusty, and the other part is cleaner - because it only recently gave way while the blue part was damaged for a while.
Estimating from the depth of thread visible, this parted in about the middle of the dropout, about exactly where the axle-tube ended.
So my guesses would be one or more of:
- QR was damaged by overtightening in the past - if anyone has used a tool other than their hands to close the QR, then this is too much.
- QR was very loose and the fork-dropout was pressing down on the QR, not being held by the axle.
- Approx 2/3 of the QR was already separated, and that last third gave way suddenly, dropping the fork clear off the end.
At that point the whole front wheel twisted sideways in the frame, bound-up against the fork and stopped suddenly. The rider still had momentum which continued and pushed you over the bars.
I would guess that you hit the ground face-first, and your hands/arms were scraped up from instinctively trying to protect your head. Presumably you were wearing a helmet which minimised the shock to the skull/brain and kept the impact from being even more severe. If you weren't wearing a helmet, you're amazingly lucky for not be more-injured.
Solutions
Obviously you need to heal first. Get a medical opinion of fitness before progressing - an injury on an injury is more than twice as bad.
You need a new helmet too. Dispose of the old one, don't keep it as a "spare"
Mechanically your bike needs a new quality skewer. However in your position some reluctance to use skewers is reasonable. For confidence reasons, I'd suggest replacing the hollow QR axle with a solid axle that uses ~15mm nuts on each side to secure the wheel.
A more-expensive solution is to replace the wheel/fork with one that uses a through-axle. These are essentially a large special bolt that replaces the axle and uses sealed bearings.
Proceedurally, a periodic once-over of the bike should show looseness before it becomes a problem. A monthly "M-Check" is a great idea, where you push/pull things, twist, spin, squeeze and shake to look for badness.
Don't let this event put you off riding. QRs are normally quite safe.
