Comparison of characteristics of patients with and without calcium pyrophosphate dihydrate crystal deposition disease who underwent total knee replacement surgery for osteoarthritis

Objective: To compare characteristics of patients with severe osteoarthritis with and without calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. Study methods: Patients undergoing total knee replacement surgery participated in this study and completed questionnaires. Radiographs of the index knee (extended anteroposterior, lateral and skyline) were reviewed for the presence of chondrocalcinosis. Synovial fluids were obtained during surgery and analyzed under compensated polarized light microscopy. Results: The presence of CPPD crystals was identified in 52.9% of 102 patients. The use of both radiographs and synovial fluid analysis increased the identification of crystals. There was no difference in the following characteristics of the patients with and without CPPD crystals: age of pain onset, gender, difficulty in performing daily functions (including cooking, standing up from chairs, using restroom, going upstairs, and going shopping), history of previous joint inflammation, use of walking aids, and number and types of medications ever used. CPPD patients underwent knee arthroplasty at older age compared to non-CPPD patients (70.3 +/- 6.37 and 67.5 +/- 7.15 years old, respectively) (P= 0.037). All but one CPPD patients were unaware of the presence of crystals. Conclusion: High prevalence of CPPD crystals was found in patients undergoing total knee replacement surgery. All but one CPPD patients were unaware of calcium deposition in the index joints. Patients with these crystals experienced similar difficulties in performing daily activities and received similar treatment to patients without CPPD crystals. CPPD patients did not undergo knee arthroplasty at earlier age than non-CPPD patients. (C) 2006 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.