A study published by Cell Press April 2nd in the Biophysical Journal shows how the nanoscale biomechanical properties of cartilage at joints change at the earliest stages of osteoarthritis, making the tissue more prone to damage during fast physical activities. The findings could improve early detection of the disease as well as tissue engineering strategies to repair damaged cartilage in patients. Osteoarthritis is the most common joint disorder, affecting about one-third of older adults, and currently there is no cure for osteoarthritis.
"Our techniques enable detection of the earliest loss of mechanical function associated with daily activities involving high loading rates, such as running and jumping," says senior study author Alan Grodzinsky of the Massachusetts Institute of Technology. "The findings can also be used to evaluate replacement tissue to ensure that it can survive these daily activities."
Osteoarthritis is a painful condition marked by the deterioration of cartilage—firm, rubbery tissue that cushions bones and prevents them from rubbing together. At the earliest stages of the disease, cartilage loses molecules called glycosaminoglycans (GAGs), which reduces the ability of the tissue to resist impact caused by physical activity. But until now, little was known about how GAG loss affects the functioning of cartilage across a wide spectrum of activities, from walking to running and jumping.
Together, the findings show how GAG depletion at the earliest disease stages could affect the nanoscale properties of cartilage, reducing the ability of this tissue to withstand high-rate activities. "We discovered that GAG-depleted tissue is most vulnerable to high rates of loading and not just the magnitude of the load," Grodzinsky says. "This finding suggests that people with early degradation of cartilage, even before such changes would be felt as pain, should be careful of dynamic activities such as running or jumping."