Agian thanks for everyones input so far and I think you probably hit the spot that I wasn't conditione enough.
The problem is that I live in the Netherlands and although I recently did some weekend hikes in very beautifull areas I didn't know were there, mostly I don't like to hike in my country. This firstly is due to my country being as flat as a pancake, so I could strap on the pack and go walking, but this hardly is training for a hike in the mountains. Secondly I live in the most densely populated area of the Netherland (there are about 17k peolpe per sq. mile here) which means that all the paths in the area are paved and that makes for very uncomfortable wlaking. Basically I started untrained on my hike and indeed this is probably the main cause for my injury.
However I also posted this question on another forum and peolpe over there came with some good arguments for sturdier boots. Besides in the Alpine countries there are boot makers whom haven been making sturdy boots for about a century or two and many many people walk on these boots, which makes me wonder that there must be a good reason why most people that I see hiking in the mountains do so on boots?
One of the repliers on that other forum came with this quote:
"I just spent 20 days straight hiking the AT in the state of Maine, using Vasque Velocity trail running shoes (my wife used Brooks Cascadias). Our packs weighed about 20-25 lbs each.
We survived OK, but had to be very careful on steep declines and slippery roots, rocks, and bog logs. We both fell fairly often (almost every day).
I disagree that 50% of AT hikers use trail hikers. I would say maybe 20% (of the thru hikers I met in Maine). Boots provide a lot more safety and security on steep rocky declines. I summitted Katahdin with a thru hiker wearing good leather hiking boots, and he was much faster at descending than I was. I had to go extremely slowly and watch my footing, whereas he could just blast his way down, landing securely even when jumping several feet down from boulders.
For flat easy hiking (none of that in Maine!) trail runners are fine (with a light pack under 25 lbs).
For anything slippery, rocky, technical, or with a heavier pack, I will in the future use sturdy leather hiking boots.
I would add that its best to avoid Goretex boots/shoes in wet climates because they will get totally soaked and then take much longer (like three days) to dry out, compared to breatheable boots/shoes. And they tend to mold and smell to high heaven.
Again, trail runner shoes would be fine for hiking in easy areas although I think it's pretty easy to get over your head now and then, like I did on Katahdin. I would use them on certain sections of the PCT, which tend to be nicely graded for horses, but not on the grueling northern part of the AT."
This is almost the same thing that I experienced, so it made me wonder....
The way I look at sturdy boots is that since they lock your ankles your knees have to work harder and so are more prone to injuries, but someone came with the argument that since your ankles are more sipported in these sturdy boots they can't make move that much and that will help your knees from also not having to make extreme movements, that seems to make sense as well.....
Some people here have suggested strength training my muscles. For the last couple of years I regurarly go to the gym and so my legs get quite some training although for the last year or so I haven't trained my legs, but after I give my knees a bit more rest I'll start training my legs again.
Also people have advised orthodics or even a visit to the podiatrist. I already walk with superfeet, which are great and I sold hiking shoes and boots for a couple of years, so I think I bought the best shoes I could find for my feet. Further I am a bit sceptic about podiatrists, since this is not a protected title in NL and anybody can call him/herself podiatrist, but it porbably can't hurt going to see one.
There were also quite some advises for streching, but I'm also sceptis about this. Studies have shown that streching didn't do anything. In fact, these studie have shown that streching is actually more likely to cause injuries if it is done incorrectly. The only benificial thing these studies could find anout streching was that it was a retual peole did before doing there exercises and that the streching just put them in a sporting state-of-mind. (I can't refer to any source other than Mens Health). But I'm willing to try anything to keep me hiking so I'll try streching as well on my next hike.
Bottom line seems to be that I need to train more, particularly on rough ground, which is difficult in my area, but for the next hike in May I'll go with a friend and we have plans to do training hikes. I'll start working on my leg muscles and next time use trekking poles again. Ultimatly, I'm planning on moving to a country with mountains; anyone have a job for me abroad?
Thanx for everyones help so far, any more insights people like to share?