That picked my interest so I dug deeper. The author cites p.252 of Brockman's "What is your dangerous idea?", which is an essay by Prof. Timothy Taylor called "The Human Brain is a Cultural Artifact". Sadly, even though its topic is indeed human brains and pelvises, the essay says nothing of the sort. So Prof. Davies made up the claim, or misattributed the citation and didn't check it.
http://oregonstate.edu/ua/ncs/archives/2012/apr/knee-injurie...
https://www.eurekalert.org/pub_releases/2016-03/uotm-waw0318...
https://www.google.com/url?sa=t&source=web&rct=j&url=http://...
4-6x is a huge difference (assuming that's accurate) so it's unlikely all of that could be behavioural. However, high heel shoes and hand-bags are known to cause lots of posture-related issues.
In Australia, young women also tend to play different sports. For example, Netball, which is notoriously strenuous on knees and ankles.
I also have serious health problems that cause belly bloat. As I get that under control, it has an impact on my hips and that always causes me knee discomfort (especially at night, trying to find a comfortable sleep position) during the time that the entire leg structure realigns. So my firsthand experience suggests that hip structure significantly impacts the knees.
Why would this evolve if there wasn't an equally strong survival pressure to having a smaller pelvis?
It doesn't even need to be knee problems, just not being able to run as fast might do.