Radial Club Hand -

General

occurs in between 1 in 30,000 & 1 in 100,000 live births
underdevelopment, or aplasia, of the radius is universally associated with thumb hypoplasia, or absence, & hypoplasia or absence of the radial aspect of the carpus
severity of the radial deficiency determines the extent of the associated deficiencies of the thumb, digits, ulna, & elbow
spectrum of anatomic deficiency can range from mild radial deviation of the wrist & minimal thumb hypoplasia, to complete absence of the thumb & radius; camptodactyly of the index, long, & ring fingers; foreshortening of the ulna; & a stiff elbow

Type	Description
I	~ulna variance is positive as a result of the foreshortened distal radius ~minor foreshortening of the radius & a prominent distal ulna ~Although there is mild radial deviation of the wrist throughout life, problems with radioulnar incongruity such as triangular fibrocartilage tears, ulnocarpal impaction syndrome, & distal radioulnar joint pain or loss of motion, usually do not occur
II	~both the proximal & distal radial physes have deficient growth, with more radial shortening & ulnar bowing ~limited proximal & distal radial physeal growth. As a consequence, the wrist is more radially deviated, & the ulna bows. The thumb hypoplasia is usually more significant, with more deficiency of the radial carpus
III	~absence of the distal two-thirds of the radius ~wrist more severely deviated, & the hand has limited mechanical support ~ulna is thickened & bowed ~associated thumb & finger abnormalities of hypoplasia & camptodactyly are more common & severe
IV	*most common ~radius is completely absent ~ulna bowing is marked ~thumb is usually absent ~index, long, & even ring fingers are often involved ~elbow may have limited range of motion ~marked limitation of hand, wrist, & forearm function

Bayne & Klug Classification

Unknown
Postulated that injury to the apical ectodermal ridge during upper limb development is the cause. Factors such as intrauterine compression, an inflammatory process, vascular insult, maternal drug exposure (thalidomide, insulin), & irradiation have all been raised as possible etiologic causes
No known genetic cause except when associated with other congenital abnormalities

severity of the soft tissue loss parallels the skeletal deficiency
preaxial muscles arise from the lateral epicondyle, & are normally innervated by the radial nerve
- radial wrist extensors & brachioradialis are absent or deficient
- pronator–flexor muscle mass is affected when its skeletal insertion sites are absent or hypoplastic
neurovascular structures will be affected
- posterior interosseous & sensory branches of the radial nerve will be absent in a severe deformity
- radial artery is usually absent
- ulnar nerve & artery are usually present & unaffected
- median nerve is usually present & serves as a neural supply to the hand with the ulnar nerve

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