Flexes the PIP joint without interfering with the MCP joint. Distal phalanx is free to allow functional use of the finger pad. Lateral springs can be worn on the radial or ulnar side of the digit. Springs can be bent to adjust tension. For size, on corresponding finger of unaffected hand, measure the distance from middle of proximal phalanx to just proximal to DIP joint on dorsal surface, as shown. When oedema is present, the next larger size may be necessary.