Calcium crystal deposits linked to worsening knee osteoarthritis, study finds

Knee osteoarthritis (OA) is the most common form of arthritis, affecting approximately 600 million people worldwide and 34 million people in the U.S. There are no treatments available that prevent its progression to date. Recommended pharmacological treatments for symptoms have either small-to moderate effects or short-term effects, often with side effects, and lifestyle behaviors such as exercise and weight loss are under-utilized.

Historically, intra-articular mineralization (IAM) or calcium crystal deposits in the joint, were thought to be of no clinical consequence, and perhaps just something that happens with older age. However, using computed tomography (CT), researchers at Boston University Chobanian & Avedisian School of Medicine have found that calcium crystal deposits in the knee can contribute to worsening of joint damage. The researchers are the first to use computerized x-ray imaging which has a markedly higher sensitivity for detection of mineralization than radiography (x-rays) to confirm for IAM in the knee.

The cartilage damage is most likely to occur in the same locations where the crystals are deposited, suggesting a localized effect. We have also showed that these crystals can contribute to knee pain in another recently published paper. Taken together, these findings highlight the important role of calcium crystals to structural damage and symptoms in knee osteoarthritis."

Tuhina Neogi, MD, PhD, corresponding author, professor of medicine, Boston University Chobanian & Avedisian School of Medicine 

Participants from the Multicenter Osteoarthritis (MOST) Study-;an NIH-funded longitudinal study of community-dwelling adults-;were evaluated for the association of IAM based on its location within the knee: anywhere in the knee, in a specific compartment of the knee (medial or lateral), and in specific sub-regions of the knee on CT at baseline with cartilage worsening on MRI over two years.

The researchers found that by using CT technology they were able to detect a higher amount of deposits than previously found by plain radiographs. With this improved detection, they found an increased risk of cartilage damage on follow-up, including among knees without damage to begin with, supporting a pathogenic role for calcium crystal deposition within the joint.

"Our findings suggest potential localized, tissue-specific effects of IA mineralization on cartilage pathology in knee OA," explains Jean Liew, MD, MS, assistant professor of medicine at the school and first author of the paper. "Now that this has been identified, we can begin to focus on identifying ways to prevent these crystal deposits from occurring to hopefully relieve pain and limit progression of joint damage in osteoarthritis," added Neogi, who also is chief of rheumatology at Boston Medical Center.

This is the third paper in a series of studies on this topic from the MOST Study, which is a large cohort study that is entering its 20^th year and was recently awarded a U19 grant for $46 million for the next phase of research regarding causes and consequences of osteoarthritis.

This study appears online in the journal Arthritis & Rheumatology.

This work was supported by NIH P30 AR072571. Jean Liew was supported by the Rheumatology Research Foundation Investigator Award. Tuhina Neogi was supported by NIH K24 AR070892, R01 AG066010, R01 AG066914, R01 NS12419. The MOST Study was supported by U01-AG-18820, U01-AG-18832, U01-AG-18947, U01-AG-19079, and U19 AG076471.