Svoboda realized something else about the cadets: The Army takes lots of blood samples from all recruits beginning when they sign up. The samples are mostly for HIV testing. Since 1985, all Army blood samples have been saved in a repository at the Walter Reed Army Institute of Research in Silver Spring, Md. To date, more than 50 million specimens have been collected and stored.

These are important considerations when researchers use patients to study a disease. The more information available (like regular blood samples), and the more similar the study population in lifestyle, the more scientists can trust study results.

Finding cadets who had torn an ACL was easy; Svoboda used a group already signed up for a clinical trail that compared repair techniques for the surgery. He then found uninjured controls matched for age, sex, height and weight in the Silver Spring repository.

Svoboda analyzed serum samples for four biomarkers that would show whether cartilage – the squishy material that lines all joints – had been formed or broken down. He and his colleagues found changes over time in the ACL group in all of the biomarkers measured.

“No one has ever looked at biomarkers like this so it’s an early study to test the possibility that markers of cartilage turnover may predict people at risk of ACL injuries, and thus osteoarthritis,” says Svoboda. Right now, he says, the study is generating many questions, which he hopes to answer with additional research.

Indeed, this was the first study to follow changes using biomarkers for cartilage turnover in patients who’ve sustained an ACL injury. In 2010, Svoboda won an Arthritis Foundation Young Investigators Award for the work from the OA Biomarker Global Initiative.