Prospective study with an echography of the 2 knees and radiography of the 2 knees (front and profile) for each patient. If found calcification on ultrasound further examination with ultrasound wrists, hips and shoulders.

Osteo-articular echography is currently recognized as an important development among rheumatologists.

Chondrocalcinosis, which can promote joint inflammation and cartilage degeneration, is highly prevalent in elderly subjects.

Osteo-articular echography is currently reconized as an important development among rheumatologists and can efficiently use to detect Chondrocalcinosis.

The aim of this study is to find a correlation between radiography and echography in detecting CPPD crystal deposition, on a sample of patients and more important with a new generation of ultrasound with a probe superficial performance.

166 patients will be enrolled in this trial and an echography and a radiography of the 2 knees (front and profile) will be done for each patient.

Ih the echography show a calcification, further exams with wrists, hips shoulders echographies will be conducted.

In case of liquid epanchement, analysis of the liquid will be carried in order to eliminate the differential diagnostic including septic arthritis

Inclusion Criteria:

• patient> 70 years
• articular pathology of the knee
• consent signed

Exclusion Criteria:

• Not covered by social security