They define calcium pyrophosphate deposition (CPPD) as an umbrella term for all instances of calcium pyrophosphate crystal occurrence. Chondrocalcinosis is defined as cartilage calcification and stress that it is not always due to calcium pyrophosphate deposition. Radiograogic chondrocalcinosis is neither sensitive nor specific for diagnosis of calcium pyrophosphate deposition.
Four clinical presentations can be associated with calcium pyrophosphate deposition:
- Asymptomatic CPPD: May be isolated chondrocalcinosis or associated with osteoarthritis. Often an incidental finding during imaging for another indication.
- Osteoarthritis with CPPD: CPPD in a joint that also shows changes of osteoarthritis. The knees are typically involved, although the distribution may be atypical for osteoarthritis elsewhere (e.g., radiocarpal or midcarpal, glenohumeral, hindfoot or midfoot). Cyst and osteophyte formation tends to be more prominent than in osteoarthritis without CPPD. Patients may have chronic symptoms and/or acute attacks of crystal-induced inflammation. In contrast to osteoarthritis without CPPD, there may be more inflammatory symptoms and signs.
- Acute CPP crystal arthritis: Acute-onset, self-limiting synovitis with CPPD (formerly known as pseudogout). Patients typically present with severe, rapid-onset joint pain, tenderness, swelling, and overlying erythema. The symptoms peak within 6–24 hours. May coexist with a septic joint.
- Chronic CPP crystal inflammatory arthritis: Chronic inflammatory oligoarthritis or polyarthritis associated with CPPD. Patients have occasional systemic upset with elevation of CRP and ESR and superimposed flares with characteristics of crystal inflammation (see above). Differential considerations include rheumatoid arthritis and other chronic inflammatory joint diseases in older adults.
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