Background Potential input of inflammation induced by calcium pyrophosphate crystals into further progression of osteoarthritis (OA) have been widely speculated , but casual association between OA progression and calcium pyrophosphate deposition disease (CPPD) development remains unclear.
Objectives To compare radiographic progression of knee osteoarthritis between patients with different clinical types of CPPD and patients with OA.
Methods Preliminary data from 2-year prospective study of 120 pts are presented. 76 pts had CPPD (33 m, 43 f) (I group), 44 – knee OA (13 m, 31 f) (II group). Mean age of pts was 60.8±10.7 years in the I group and 62.0±9.4 years in the II group. According to EULAR terminology CPPD patients were grouped into 3 clinical arms: chronic arthritis (n=43), acute arthritis (n=7) and OA with CPPD (n=26). CPPD was diagnosed based on McCarty criteria, OA diagnosis fulfilled ACR criteria. X-ray of the knee joints was performed in all pts in anterior-posterior and lateral projections. Using radiographs of the knees we assessed joint space narrowing, osteophytes, presence of osteosclerosis and cysts in the tibiofemoral (medial and lateral) and patellofemoral compartments. Kellgren and Lawrence (KL) score (0-4) was also determined. Progression was defined as an increase in ≥1 in the radiographic features assessed or total KL score in either knee during follow-up. Routinely were also measured and calculated: body mass index (BMI), WOMAC, self-assessment questionnaire the Lequesne survey, HAQ and pain on VAS. Serum levels of hsCRP were also performed
Results At baseline pts were comparable by age, BMI, number of affected joints, radiographic stage of knee osteoarthritis, pain level, Womac, Lequesne and HAQ scores. Radiographic progression was observed in 30 (39%) pts in I group and in 10 (22%) pts of the II group (p=0.06). Among pts with different CPPD types radiographic progression was registered in 23 (46%) pts with chronic or acute arthritis and in 7 (27%) with OA with CPPD (p=0.10). Radiographic progression rate in OA with CPPD pts was similar to that in pts with OA (p=0.69), but in pts with chronic or acute arthritis in CPPD this rate was higher than in pts with OA (p=0.018).
Mean serum hsCRP level in pts with CPPD and OA was similar (3.98±2.1 mg/l vs 2.52±1.33 mg/l, correspondingly) (p=0.78). Serum hsCRP levels in pts with acute or chronic arthritis in CPPD was higher than in pts with OA (12.32±8,01 mg/l vs 2.52±1.33 mg/l, correspondingly) (p=0.002) and in pts with OA and CPPD (12.32±8.01 mg/l vs 2.16±1.32 mg/l, correspondingly) (p=0.003). Knee replacement surgery was required in 5 (6%) pts with CPPD and in 4 (9%) – with OA (p=0.61).
Conclusions Rate of radiographic progression of knee osteoarthritis is comparable between pts with OA and CPPD. Although in pts with acute or chronic arthritis in CPPD radiographic progression of knee osteoarthritis was more significant if compared to OA or OA with CPPD. The potential cause for this discrepancy may be chronic inflammation induced by CPP crystals
Liu YZ, Jackson AP, Cosgrove SD. Contribution of calcium-containing crystals to cartilage degradation and synovial inflammation in osteoarthritis. Osteoarthritis Cartilage. 2009;17(10):1333-40.
Disclosure of Interest None declared