The old adage that running will ruin your knees has long been debunked.
(If you need another example, here's one from last year.)
However, if you already have a 'bum' knee that's suffering from osteoarthritis, should running be avoided?
A new study in the journal of Clinical Rheumatology, led by Grace Low, tested 5,000 Americans. Within that group, 1,203 of them had OA (osteoarthritis) in at least one knee. Of that group, 138 were runners. (And yes, I know this isn't a big group. However, these results were both surprising and promising enough to likely elicit further research)
After 4y, the group returned to the lab for further testing and the results of the running group were contrary to what researchers expected.
They found 'little evidence to suggest that running is harmful in this cohort'. Even after adjusting for characteristics like BMI and age, runners remained 70% more likely to (not only avoid worsening) but see improvements in their symptoms.
Again, this is a small group within a proper sized testing cohort. Still, it's promising and will hopefully entice further directed research in this vein.
With over 30 million Americans suffering from OA, it's no surprise everyone is starving for evidence based research on how best to avoid & manage it. Delving further into this study is Alex Hutchinson.
Now the tough questions? As a sufferer of OA in my knees, will I lace up and start running? Yes, a little. However, I'll stick with my mountain bike & skis for a little longer.
The biggest key in my opinion, is to simply KEEP MOVING!