Ulnar deviation

For ulnar deviation as a type of hand movement, see Ulnar deviation under Anatomical terms of location.

Ulnar deviation, also known as ulnar drift, is a hand deformity in which the swelling of the metacarpophalangeal joints (the big knuckles at the base of the fingers) causes the fingers to become displaced, tending towards the little finger. Its name comes from the displacement toward the ulna (as opposed to radial deviation, in which fingers are displaced toward the radius). Ulnar deviation is likely to be a characteristic of rheumatoid arthritis, more than of osteoarthritis. Consideration should also be given to Pigmented Villonodular Synovitis, in the setting of ulnar deviation and metacarpophalangeal synovitis.