My worst would have to be a broken shoulder.
I slipped on a damp rock when trying to step over it. Went over onto my side and hit my shoulder on the rock face next to it. At the time I thought it may have been a popped in/out dislocation which wasn't hurting and I didn't want to spoil the day for the rest of the guys. So I sat there and waited for them to come back and collect me on the way back to the car. 30 minutes of sitting alone before we got back to the car and one of the guys drove back to Swansea where I'd left my car. Being the plonker I am I deceided to drive home one handed, with my right hand tucked into the neck of my shirt. I drove straight to casualty after makig one of the worst phonecalls of my life, having to ask the wife (at least she was at the time!) to meet me in casualty. This was made all the worst as she hadn't wanted me to go with the guys in the first place and I got a massive "I told you so!".
After xrays and being prodded we found that a chunk of bone had broken away from the ball at the top of my right humerus. Unfortunately it happened to be the bit with a major tendon attached to it. So every time I tried to use my arm I was pulling the bone out of place! After 6 weeks of no right arm (it was almost totally immobile) things began to get better. Mind you, that was 6 or 7 ears ago and I still have pain in the shoulder every day and have difficulty raising the arm above shoulder height.
Oh, by the way, did I mention that the accident was around 100' underground while caving at Penwyltin the Swansea valley? It was a lot of fun getting myself out of the cave with only one arm