In general there are five types of<unk> , originally described by Muller in 1937 and improved by Blauth, Buck-Gramcko and Manske. - Type I: the<unk>  is small, normal components are present but undersized. Two muscles of the<unk> , the abductor pollicis brevis and opponens pollicis, are not fully developed ,. This type requires no surgical treatment in most cases. - Type II is characterized by a tight web space between the<unk>  and index finger which restricts movement, poor thenar muscles and an unstable middle joint of the<unk>  metacarpophalangeal joint. This unstable<unk>  is best treated with reconstruction of the mentioned structures. - Type III<unk> s are subclassified into two subtypes by Manske. Both involve a less developed first metacarpal and a nearly absent thenar musculature. Type III-A has a fairly stable carpometacarpal joint and type III-B does not. The function of the<unk>  is poor. Children with type III are the most difficult patients to treat because there is not one specific treatment for the hypoplastic<unk> . The limit between pollicization and reconstruction varies. Some surgeons have said that type IIIA is amenable to reconstruction and not type IIIB. Others say type IIIA is not suitable for reconstruction too. Based on the diagnosis the doctor has to decide what is needed to be done to obtain a more functional<unk> , i.e. reconstruction or pollicization. In this group careful attention should be paid to anomalous tendons coming from the forearm (extrinsic muscles, like an aberrant long<unk>  flexor – flexor pollicis longus). - Type IV is called a pouce flottant, floating<unk> . This<unk>  has a neurovascular bundle which connects it to the skin of the hand. There’s no evidence of thenar muscles and rarely functioning tendons. It has a few rudimentary bones. Children with type IV are difficult to reconstruct. This type is nearly always treated with an index finger pollicization to improve hand function. - Type V is no<unk>  at all and requires pollicization.
Thumb hypoplasia
Maxillary hypoplasia
Renal hypoplasia
Condylar hypoplasia
Radial aplasia
Hemifacial microsomia
Webbed neck
Ape hand deformity