[Role of radiology in the diagnosis of joint chondrocalcinosis. The so-called atypical symptomatic aspects].

In a preceding article, we described "pseudogout" which is the expression of an episode of acute synovitis related to microcrystals of dehydrated calcium pyrophosphate invading the joint. This brutal episode of inflammation, predominantly occurring in the knee joint, is the most spectacular, most frequent and most characteristic manifestation of articular chondrocalcinosis. We attempted to demonstrate the important role of radiographs in the diagnosis, discovering in many cases the microcrystal impregnation of cartilage and fibrocartilage. But articular chondrocalcinosis, as has been shown by a large number of clinical and radiological surveys, may present a wide range of atypical or misleading forms, much different from the classic pseudogout. Among the different clinical presentations, some have no particularly special radiographic expression, showing only the common chondrocalcinosis lesions seen during the acute episodes of microcrystal related synovitis. This is the case in different situations of inflammation, notably subacute arthritis, purely algic forms and exsudative forms (chronic hydarthrosis, haemarthrosis). Complete clinical latency is also observed in certain cases. But many cases of articular chondrocalcinosis involve manifest radiological lesions which often appear to be secondary. This may occur in chronic inflammatory forms of chondrocalcinosis which can simulate rheumatoid polyarthritis. Careful analysis of the symptomatology should help to avoid confusion, especially when the radiograph reveals only degenerative lesions which often cause destructive damages. In other cases, a perfectly characteristic articular chondrocalcinosis is associated with typical polyarticular lesions of osteoarthritis. These cases often have the particularity of involving joints usually spared by the common arthrosic disease, especially in the upper limbs. They are also remarkable due to the amount of lytic damage. The deep destructive damage to joints during chondrocalcinosis may produced a particularly striking picture. Such damage is seen in approximately one-third of the cases. The onset is marked by sudden renewal of former arthrosic-type pain and by the development of major functional incapacity. Often, the radiograph is the only examination capable of revealing the diagnosis. The extent of bone destruction varies greatly. Sometimes it is limited to subchondral bone but in other cases underlying bony structures are also involved leading to extensive damage to the epiphysis. The distribution of lytic lesions varies. Damage may occur in the knee, the coxofemoral and the shoulder joints. Surgery is often absolutely indicated. In a number of cases of chondrocalcinosis, especially those involving the knee and the shoulder, true intraarticular foreign bodies may be encountered, opaque calcified or ossified formations simulating osteochondromatosis, existing along with destructive damages.(ABSTRACT TRUNCATED AT 400 WORDS)