It is a deformity in which the middle joint of the finger cannot be straightened. It usually occurs after trauma. The flattening of the finger is achieved by a highly complex mechanism. A tendon leading to the midline on the finger mainly smoothes the lower and middle nodes (proximal and middle phalanx) of the finger, while tendons from both sides of the finger straighten the end node (distal phalanx). The tendon located in the middle of the button marrow deformity was injured at the proximal phalanx close to the middle joint.
Due to its typical appearance, it is easily diagnosed. It is a complication seen in rheumatic diseases besides traumas.
