In a new study, engineers at the Massachusetts Institute of Technology (MIT) have found that high-impact exercise may worsen cartilage damage in the earlier stages of arthritis. By studying the molecular properties of cartilage, MIT engineers have discovered how the early stages of arthritis can make the tissue more susceptible to damage from physical activities, such as jumping or running.
The MIT research team aimed to investigate how the molecular structure of glycosaminoglycans (GAGs), which are the highly charged molecules that comprise aggrecans in cartilage, generate stiffening over a wide range of activity, from sitting to running to jumping at a high speed. The engineers developed a new, sensitive type of atomic force microscopy (AFM), which allowed them to measure how aggrecan reacts at the nanoscale to very high loading rates.
With this system, researchers compared normal cartilage and cartilage treated with an enzyme that destroys GAG chains, which mimics the initial stages of osteoarthritis. The research team found that when normal cartilage was exposed to very high loading rates, it was able to absorb fluid and stiffen normally. Fluid did leak out rapidly in GAG-depleted tissue, however.
The study's findings may help researchers develop tests to diagnose arthritis in patients earlier who may be at high risk for the condition and can also aid engineers in designing replacement cartilage. The results also suggest that athletes who have endured a traumatic knee injury should be cautious when returning to play following surgery.
The researchers are presently working to identify potential drugs that may halt the loss of aggrecan and design tissue scaffolds that could be implanted into patients in need of cartilage-replacement surgery. The findings of the study were published in a paper in the Biophysical Journal.
[Source: Biophysical Journal]