Calcium crystal deposits in the knee joint may contribute to worsening arthritis despite a belief they are harmless, a US study warns.

Up until now, calcium crystal deposits in the knee were thought to be of no clinical consequence and just something that occurred with older age, the researchers said.

But using the CT scans of nearly 1700 patients, a team from the Boston University School of Medicine was able to detect a higher amount of deposits than previously revealed by regular X-ray imaging.

These improved scans allowed researchers to track an increased risk of cartilage damage from the deposits, including among knees that had not appeared damaged in earlier imaging.