It might be worthwhile to consider seatbelt policy as a cause of injuries in these instances. I'm just SLF, but I notice on domestic U.S. flights that carriers tend to leave the seatbelt sign on for most of the climb phase, during even light turbulence, and for the entire descent. The result? Lines of people at the bathroom when the seatbelt light goes off and therefore out of their seats in more vulnerable positions.
When I fly ANA to Japan, I notice they take the seatbelt sign off after takeoff and it generally stays off even when turbulence gets rather noticeable. So, lines rarely form at the toilets and more people are likely to be seated and at least have the chance to be buckled up should a sudden bad bump come along.
I realize long flight time permits toilet visits to be more spread out, but the more judicious use of the seatbelt sign is still a point to consider.