Here's a story about Bu's patellar luxation and how having pet insurance with Healthy Paws helped pay for the surgery. It seems that a day at the park aggrevated Bu's patellar luxation.
What makes this significant is that Healthy Paws is one of several companies that now cover hereditary and/or congenital conditions.
Some companies catagorize patellar (kneecap) luxation as either hereditary or congenital and don't cover it. This brings up once again the importance of getting a policy that does cover hereditary/congenital conditions and preferably from a company that offers more than token coverage. With most companies, the policy must have been effective before the hereditary/congenital problem was diagnosed.