swan neck deformity /swän/ [D, zwaan + AS, hnecca, neck; L, deformis, misshapen] , 1. an abnormal condition of the finger characterized by flexion of the distal interphalangeal joint and hyperextension of the proximal interphalangeal joint. It is caused by a taut profundus tendon in the presence of a weakened distal interphalangeal joint and may be combined with a volar plate rupture. The condition is seen most often in rheumatoid arthritis. Also called zig-zag. 2. a structural abnormality of the kidney tubules associated with rickets. The kidney tubule connecting the glomerulus with the convoluted part of the tubule is narrowed into a configuration referred to as “swan neck.” There are also a thinning and atrophy of the distal tubule and a shortening of the convoluted part.
