Presence of Intra-Articular Mineralization May Lead to Worsening Pain in Knee OA

The presence of intra-articular (IA) mineralization may increase the likelihood of experiencing knee pain that is persistent and worsening, among patients with knee osteoarthritis (OA). Treatment focus on IA mineralization could possibly help alleviate pain and improve knee OA symptoms, according to study results published in Arthritis Rheumatology.

Investigators examined how the presence of IA mineralization, detected using computerized tomography (CT) scans, relates to the development of knee pain over time.

A longitudinal analysis of the Multicenter Osteoarthritis (MOST) study (ClinicalTrials.gov Identifier: NCT03033238) was conducted. Researchers categorized knee pain based on frequency and severity: frequent knee pain (FKP), intermittent or constant knee pain worsening, and pain severity worsening.

Knee imaging was conducted at baseline visit and pain assessments were completed every 8 months for a total of 2 years.

A total of 2093 patients (4168 knees) were included in the analysis. More than half of the study participants were women (57%) and mean patient age was 61 years.

Computerized tomography-detected mineralization was present among 13.3% of patients, anywhere in the joint. A total of 10.2% of knees had some form of IA mineralization (found in cartilage, meniscus, and/or capsule) on CT scans, while the prevalence on radiographs was 6%. 

The presence of IA mineralization in the joint was strongly associated with likelihood of developing FKP (odds ratio [OR], 1.71; 95% CI, 1.25-2.35), but no other types of pain.

In particular, mineralization in the cartilage increased the likelihood of experiencing FKP by 96% and frequent intermittent/constant pain by 83%, compared against patients with no cartilage mineralization. However, IA mineralization in the cartilage itself did not have a significant impact on the severity of pain (β, 0.17; 95% CI, -0.05 to 0.40).

Greater IA mineralization within any part of the knee was associated with increased odds for all pain outcomes (ORs ranged from 2.14-2.2).

The investigators noted it was unclear whether the location of IA mineralization among specific tissue types, (eg, cartilage, meniscus, capsule) was clinically relevant to the development of pain, though slight variations in the level of risk associated with each type of tissue were present.

Limitations of this study included reduced generalizability among patient cohorts. Additionally, fluctuations in pain occurring between study visits and subsequent development of mineralization were unable to be studied. Finally, specific crystal types were not assessed.

The study authors concluded, “These findings implicate calcium crystal deposition in changing pain patterns over time in knee OA. These insights also raise the potential for developing and testing therapies directed towards crystal deposition and downstream mediators to improve knee OA symptoms.”

Disclosure: One or more study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

This article originally appeared on Rheumatology Advisor