Try this test. Getting out of your chair rising on single leg.
Basically there is research to say that if you can do 16+ on each leg you will be in a low risk category for knee and hip problems. If you can do 22+ you reduce the risk even more.
I could do 7 on each leg (it's hard ). Great exercise to practice at work though ?
This video came from www.mickhughes.physio
I couldn't link to the blog post unfortunately - you'll have to go there and search it.