I
|
Narrow, small (near normal)
Minimal underdevelopment
Stable
Mild intrinsic hypoplasia
|
IIA
|
Narrow, small
Adduction contracture
Uniaxial Ulnar Collateral ligament (UCL) Metacarpophalangeal (MP) joint
instability Poorly developed thenar muscles
|
IIB |
2A plus bi-axial/global MP joint instability and/or
extrinsic anomalies |
IIC |
2B plus inadequate Carpometacarpal (CMC)
joint |
IIIA
|
Aplasia proximal 1/3 thumb MC (absent CMC joint)
Severe underdevelopment
Unstable
Extensive intrinsic and extrinsic musculotendinous deficiencies
|
IIIB
|
3A with aplasia proximal 2/3 thumb
Metacarpal (absent CMC joint)
|
IV |
Absent Metacarpal (Pouce flottant) |
V |
Absent thumb |