Cartilage mineralization is common in end-stage osteoarthritis

Contrary to earlier reports, mineralization of articular cartilage is a common event in end-stage osteoarthritis (OA) and is closely associated with disease progression. There is a significant correlation between clinical symptoms and the amount of mineralized cartilage.

Fuerst and coworkers examined synovial fluid and cartilage from 120 patients with knee OA who were undergoing total knee arthroplasty. Their investigation included radiography, digital-content radiography (DCR), histological assessment of cartilage, and electron microscopy.

All patients who underwent DCR had evidence of mineralization-which sometimes was missed by conventional radiography. Mineral deposits existed in 100% of articular cartilage and 62.5% of meniscal tissue. Other methods of evaluation were less sensitive; microscopy, for example, showed crystals in 60% of the patients examined. The extent of mineralization was directly correlated with the patient’s preoperative clinical condition but was unrelated to his or her age. The extent of mineralization increased with the extent of cartilage destruction, and the content consisted mainly of basic calcium phosphate (BCP) rather than calcium pyrophosphate dihydrate crystals.

The authors suggested that the finding of mineralization with BCP in all cartilage specimens from patients with OA may have a significant effect on diagnostic strategies, treatment concepts, and understanding of OA.