I got told it was more for trauma or vaginal bleeding, but best to call the unit and see what they advise. I fell onto my bump a lot with my first and never had to have another injection as they were only little falls
I asked about my three year old climbing all over me and banging into me and they said basically if it really hurt and it was bothering me, I'd need to go in for anti-d
I got told to go in if I've had a bump or fall. I'd always ring up and check for sure but if it was a hard knee I'd think they'd say yes.