Correlation of digital nerves to skin surface creases. Small finger ulnar digital nerve courses obliquely across hand under line drawn from small finger ulnar palmar crease (4) to intersection point of Kaplan cardinal line (1) and one parallel to the ulnar border of ring finger (2). Similarly, index radial digital nerve courses obliquely across hand under line drawn from index finger radial palmar digital crease (4) to intersection point of Kaplan cardinal line (1) and one parallel to radial border of middle finger (3). (Redrawn from Calandruccio JH, Hecox SE: Reoperative Dupuytren’s contracture. In Duncan SFM, editor: Reoperative hand surgery, New York, 2012, Springer Science+Business Media LLC.)