Congenital Anomaly Classification

1.  Failure of Formation

 

A Transverse Failure

 

Congenital Amputation

Phocomelia

 

B Axial / Longitudinal Failure

 

Radial Club Hand

Ulnar Club Hand

Cleft Hand / Foot

 

2.  Failure of Separation

 

Syndactyly 

Apert's Syndrome

 

3.  Duplication

 

Polydactyly

- pre axial (tibia & radius)

- post axial (fibula & ulna)

 

4. Overgrowth

 

Hemihypertrophy

Macrodactyly - commonest of these

 

5.  Undergrowth

 

Hypoplastic thumb - commonest of these

Hypoplastic hand & digits

 

6.  Congenital constriction bands

 

7.   Miscellaneous 

 

Congenital Trigger Digits

Camptodactylty

Kirner's Deformity

Delta Phalanx

Dyschondriostosis 

Madelung's Deformity

 

Terminology 

 

Amelia

- complete absence of limb

 

Phocomelia

- seal or flipper limb

- terminal portion attached to trunk

- intercalary defect

- deformed hand with only 3-4 digits

 

Hemimelia 

 

Absence of major portion of limb

- Radial / Ulnar / Tibial / Fibula

 

Complete

- entire distal 1/2 of limb absent

 

Incomplete

- greater portion of distal 1/2 of limb absent

 

Paraxial

- preaxial or postaxial portion of distal 1/2 of limb absent

- preaxial: thumb / radial, tibia

- postaxial: little finger / ulna, fibula

 

Terminal

- no unaffected parts distal

 

Transverse

- defect extends transversely

- complete absence of some part distal to some point on the upper extremity

- common levels are: fingers, upper third forearm, midcarpal

- 98% unilateral

- aetiology unknown except for thalidomide

 

Intercalary

- middle portion of limb deficient

- proximal & distal portions present

- can be transverse or paraxial 

- ie fibula hemimelia may have lesser toes present

 

Acrosyndactyly

- fusion of fingers distally with proximal fenestrations

 

Brachysyndactyly

- shortening of syndactyl digit

 

Aetiology

 

Normal development

- limb buds develop at 4/52

- apical ectodermal ridge controls underlying mesoderm

- limb segments develop in proximal to distal sequence

- skeletal elements formed as cartilaginous models

- models ossify

- clefts form & develop joints

- embryonic skeleton well formed at 7/52

- sonic hedgehog gene important

 

Abnormal Development

 

50% unknown

- genetic factors - Trisomy 21 / 18 / 13

- environmental factors - thalidomide / warfarin / dilantin well established

- combination

 

May cause

- arrest of development of embryonic limb

- destruction of structures already formed

 

Must occur between 4th and 7th week