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What is Arthritis mutilans and explain in detail?
Arthritis mutilans is a rare medical condition involving severe inflammation damaging the joints of the hands and feet, and resulting in deformation and problems with moving the affected areas; it can also affect the spine. As an uncommon arthropathy, arthritis mutilans was originally described as affecting the hands, feet, fingers, and/or toes, but can refer in general to severe derangement of any joint damaged by arthropathy. First described in modern medical literature by Marie and Leri in 1913, in the hands, arthritis mutilans is also known as opera glass hand (la main en lorgnette in French), or chronic absorptive arthritis. Sometimes there is foot involvement in which toes shorten and on which painful calluses develop in a condition known as opera glass foot, or pied en lorgnette.

Signs and symptoms
For a person with arthritis mutilans in the hands, the fingers become shortened by arthritis, and the shortening may become severe enough that the hand looks paw-like, with the first deformity occurring at the interphalangeal and metacarpophalangeal joints. The excess skin from the shortening of the phalanx bones becomes folded transversely, as if retracted into one another like opera glasses, hence the description la main en lorgnette. As the condition worsens, luxation, phalangeal and metacarpal bone absorption, and skeletal architecture loss in the fingers occurs.

Cause
Arthritis mutilans occurs mainly in people who have pre-existing psoriatic arthritis, but can occur, if less often, in advanced rheumatoid arthritis; it can also occur independently