principles

Last reviewed 01/2018

The principles of pollicisation can be set out in a stepwise manner:

• skin flaps are designed; a standard technique entails a midline dorsal cut along the index finger proximal phalanx connected to an extension along the digital crease and for exposure, down onto the thenar eminence
• dorsal skin flaps are raised
• the dorsal veins are identified and protected with dissection proximally to allow transposition
• the extensor tendon is demarcated and the lateral bands are divided proximally
• the index finger metacarpal is divided at the level of physis; the rest of the proximal index finger metacarpal shaft is removed but with preservation of intrinsic muscles
• palmar flaps are raised
• the neurovascular bundles are identified in the palm and dissected back; a small amount of fat is ideally preserved around them to protect the small venae comitantes; interfascicular nerve dissection may be necessary to permit adequate mobilisation of the digit
• the flexor tendons are dissected proximally with release of the A1 pulley to allow transposition
• the metacarpal head is either sutured or K wired into extension to prevent hyperextension of the pollicised digit with use
• the digit is transposed and secured with K wires through the index finger metacarpal head in an optimal functional position, typically:
  • 120-140 degrees of pronation
  • 40 degrees of palmar abduction
  • length adjusted so that the tip of the new thumb aligns with the middle finger proximal interphalangeal joint
• extrinsic tendons are shortened as required, typically by imbrication; more relevant to the extensors than the flexors
• intrinsic muscles are reattached to transposed metacarpal
• skin is sutured

Typically this results in the following rearrangement of structures: