Overgrowth

Macrodactyly

  • Congenital localized hamartomatous enlargement of skeletal and soft tissue components which gives rise to an abnormally large digit, which may reach grotesque proportions.
  • Involvement may be limited to single digit or involve hand and forearm
  • All the structures in the involved part are enlarged in true macrodactyly
  • Need to be distinguished from other forms of enlarged digits and other specialized tissue malformations such as
  1. Hemangiomas
  2. AV malformation
  3. Lymphedema
  4. Klippel trenaunay weber syndrome
  5. Olliers

Incidence

  • Rare, 0.9% of upper limb anomalies
  • M>F
  • 95% unilateral
  • IF>MF>thumb>RF>LF
  • Commonly involves multiple digits
  • Most are sporadic

Etiology

Three possible causes

  1. abnormal nerve supply – most likely
  2. abnormal blood supply
  3. abnormal humoral mechanisms

3 Types

Type I digital gigantism with lipofibromatous hamartoma of a peripheral nerve

Type II digital gigantism associated with neurofibromatosis

Type III hyperostotic digital gigantism

Classification

1)Static –enlarged at birth but grows in proportion to other digits

2)Progressive -Progressively disproportionate enlargement of involved areas with advancing age and often results angulation of the digit

Anatomic pathology

  • All structures in the finger enlarge
  • Phalangeal enlargement in both the longitudinal and transverse directions
  • Large increase in subcut fat and fibrous stroma
  • Skin thickens
  • Nerves thick and tortuous and fatty infiltration

Clinical features

  • convex sides grow quicker, so radial digits angulate ulnarly and ulnar digits radially
  • if 2 adjacent fingers involved, they grow away from each other
  • involved thumb abducts and hyperextends
  • Progressive growth stops with epiphyseal fusion
  • Sensation normal
  • Significant aesthetic and functional problem being unsightly and stiff
  • Nerves often enlarged and soft tissue hypertrophy prevents flexion
  • May develop carpal tunnel syndrome
  • KeliKan - used term nerve territory orientated hypertrophy (NTOM) to describe most common form ie the fingers supplied by the median or ulnar nerve only become involved
  • Marked soft tissue hypertrophy on palmar surface causes the distal IP joint to assume hyper extended position obstructing flexion. With age calcification of tendons and osteophytes -> knobby appearance.

Treatment

  • Surgical treatment difficult

1)Amputation

  1. recommended if only one digit involved

2)Epiphysiodesis

  1. performed on all 3 phalanges when digit reaches an estimated normal adult size (compare to father’s fingers)
  2. Rarely done on metacarpus unless this shows increased length.

3)Carpal tunnel release

  1. often need to be carried into forearm

4)Bulk reduction

  1. usually in two stages one half of a finger at one time
  2. Longitudinal incision n/v bundle identified and fat on that half of finger removed and the excess skin excised
  3. Narrow bone by burring down on the side of the finger
  4. Risk of skin necrosis

5)Nerve Stripping

  1. Branches are stripped except terminal ones (to reduce growth stimuli)
  2. Excision of hypertrophic digital nerve with or without direct end-end repair

6)Finger shortening

  1. Distal phalanx osteotomies with or without preservation of the nail

TsugeBarsky

7)Angulation Osteotomy

  1. Lateral closing wedge
  2. Usually distal metaphysis of the middle and proximal phalanges