Osteoarthritis of the knee is a common condition in humans and in their canine companions. An estimated 20% of dogs older than a year and 12% of people between 25 and 74 will develop the condition.
The causes and mechanisms are not well understood, however age and weight are considered major risk factors.
Injuries also lead to developing the disease. In fact one of the most common of all sports injuries in humans as well as dogs – a tear of the anterior cruciate ligament — is the leading cause of post traumatic osteoarthritis.
The mystery is why many, but not all, dogs and people with ACL injuries develop post traumatic osteoarthritis, medically referred to as PTOA. Now, a study of dogs at Cornell University’s veterinary school, published this month in Scientific Reports, offers clues to the potential for developing PTOA.
Researchers led by Dr. Heidi Reesink, assistant professor in equine health at Cornell, found that changes in the production of lubricin, a joint lubricating protein, could be a precursor to developing joint disease.
Lubricin is critical to smooth joint functioning. “We know that if a person or animal doesn’t make that protein, they will develop devastating joint disease affecting all the major weight-bearing joints,” says Reesink.
The prevailing view among veterinarians and physicians is that lubricin production declines after injury, leading to the development of PTOA. “The dogma in this field has been that lubricin decreases in joint disease,” Reesink said.
But the study found that in canine patients with a knee ligament tear lubricin increased and it was correlated with the development of osteoarthritis.
“This indicates that the presence of increased lubricin might actually be a biomarker for predicting future osteoarthritis,” said Reesink. “We also saw increased lubricin in dogs months to years after they injured their ACLs, suggesting that lubricin might be an indicator of ongoing joint instability.”
Increased lubricin could serve as a tipoff to clinicians to intervene with early treatments to ward off or slow the development of osteoarthritis, not just in dogs, but in people, too.