 Flexion Therapeutics NASDAQ:FLXN may be one of the best-kept secrets in biotech. The company has a product that addresses a condition that affects a growing number of Americans. But FLXN stock started tumbling at the beginning of the year.Source: Shutterstock And despite positive news about its flagship drug, Zilretta, its struggling to reclaim its gains.Theres a reason for that. The economy cant fully heal without a vaccine for the novel coronavirus or effective antiviral treatments. We both know it, and investors are investing in biotech accordingly.InvestorPlace - Stock Market News, Stock Advice Trading Tips 10 Cybersecurity Stocks We Need Now More Than EverFortunately, it seems that the field is narrowing when it comes to viable vaccine candidates. And that means its a perfect time to take a look at a company thats managed to do some impressive things in the midst of a pandemic.Zilretta is Flexions flagship osteoarthritis drug. Prior to the lockdown measures that engulfed large parts of the country, sales of Zilretta were growing steadily. Revenue has dipped due to the pandemic. But a closer look shows that the company is seeding Zilretta into orthopedists offices even in the midst of those struggles.Flexion addresses a condition which is likely to see growing demand. The only real question for Flexion at this time is when will sales get back to normal? America is Only Getting OlderThere are two specific trends that are bullish for FLXN stock. The first is the inexorable aging of America. I always knew that the country was getting older, but I more or less accepted it at face value. But just doing a smidgen of research for this article, I was stunned at how old were getting.According to estimates from the U.S. Census Bureau, about 16 of the U.S. population was 65 years or older in 2018. The Census Bureau also predicts that by 2035, seniors will outnumber children.And the United Nations has its own prediction: that by 2050, one out of every five people in the United States will be age 65 or older.One reason for this is that Americans are able to live longer because of advances in science and medicine. Such as the way we can treat conditions that would have prevented early generations from having the freedom of movement they would have liked. Our Knees Are Likely to AcheThe second trend is that as America gets older, and heavier, there is a likelihood that individuals will develop osteoarthritis.Here is an excerpt from a journal article published by the National Center for Biotechnology Information NCBI:Osteoarthritis OA is the most common joint disorder in the United States. Symptomatic knee OA occurs in 10 men and 13 in women aged 60 years or older. The number of people affected with symptomatic OA is likely to increase due to the aging of the population and the obesity epidemic.The article went on to say that Pain from OA is a key symptom in the decision to seek medical care and is an important antecedent to disability.After tearing cartilage in my knee at the age of 24, Im learning to live with mild arthritis that will in all likelihood turn into osteoarthritis. Its real. And Flexion is on the forefront of that change. The Pipeline Is Temporarily CloggedCovid-19 vaccine candidates are moving at warp speed thanks to the U.S. governments Operation Warp Speed Program. However the pandemic is putting other clinical trials on hold. And that includes Flexions getting an expanded use label for Zilretta to treat a different condition, synovitis. In addition, Flexion has two other drug candidates that are being delayed.But all of that is secondary to the issue at hand. Flexions short- and medium-term fortunes are clearly tied to Zilretta. Is Now the Time to Buy FLXN Stock?There are worse options, particularly when several companies with Covid-19 vaccine candidates are penny stocks without a product on the market. Flexion has a proven winner in Zilretta and potentially more on the way.Flexion is not yet profitable. However, analysts are clearly bullish on the short-term prospects for FLXN stock. The company just released an overview on Zilrettas sales in the second quarter. After initial excitement, the stock has settled into a tight range. However, that may change after Flexion reports earnings on Aug. 4.Chris Markoch is a freelance financial copywriter who has been covering the market for over five years. He has been writing for InvestorPlace since 2019. As of this writing, Chris Markoch did not hold a position in any of the aforementioned securities. More From InvestorPlace Why Everyone Is Investing in 5G All WRONG Americas 1 Stock Picker Reveals His Next 1,000 Winner Revolutionary Tech Behind 5G Rollout Is Being Pioneered By This 1 Company Radical New Battery Could Dismantle Oil Markets The post OK Boomer, Flexion Stock Is Made For You appeared first on InvestorPlace. 