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