Practice Essentials
Ulnar clubhand is much less common than radial clubhand and is more appropriately referred to as ulnar deficiencies of the forearm. [1] Most cases are sporadic in occurrence, though genetic syndromes are associated with ulnar dysplasia. [2, 3]
Close to 70% of cases of ulnar clubhand are unilateral. A partial rather than complete absence of the ulna is common. Ulnar shortening with radial bowing and abnormal digits is the classic presentation of this condition, and digital anomalies can be found in close to 90% of cases with postaxial absence of ulnar rays. [4] The fourth and fifth metacarpals, as well as the capitate, lunate, triquetrum, hamate, and pisiform, are absent or deformed.
Synostosis with the humerus is possible when the ulna is present; radiohumeral synostosis can also be present. The radial head is dislocated in close to 50% of cases.
Radial bowing is produced by the tethering effect of the fibrocartilaginous ulnar anlage, which can also tether the carpus, producing limitation of wrist movement. The radiocarpal joint has a fixed ulnar deviation in these cases. In most cases, however, function is very good, and the carpus can be actively centralized. The presence of a thumb makes for a functional hand, unlike the case for radial clubhands.
In patients with ulnar clubhand, surgery is indicated for the following (see Treatment):
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Ulnar deviation
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Anlage
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Bowing of radius
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Forearm in less than useful rotation
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Radial head dislocation
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Unstable elbow
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Radiohumeral synostosis
Nonspecific contraindications for ulnar clubhand surgery are as follows:
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Presence of no or minimal functional deficit
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Any surgical risk factor due to associated syndromes
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Severely affected limb and poor neurologic function
Pathophysiology
Elliott et al studied 28 patients with posterior congenital dislocation of the radial head and proximal radioulnar fusion to help determine whether they are different clinical manifestations of the same primary developmental abnormality. [5] Of 28 patients studied, 16 had bilateral involvement (eight with posterior dislocation of the radial head only, five with posterior radial head dislocation with radioulnar fusion, and two with radioulnar fusion without dislocation). Nine patients had only left-side involvement, and three had only right-side involvement.
According to Elliott et al, the suggestion of a developmental relation between posterior dislocation of the radial head and proximal radioulnar fusion is supported by the fact that the two anomalies can occur in the same patient. [5] In addition, they noted that both anomalies can be seen in different patients with the same genetic diagnosis, a finding that further supports the notion that these defects are developmentally related.
Oberg et al described the rare combination of right radial and left ulnar deficiencies in two cases. [6] In one case, there was a history of two separate, distinct episodes of bleeding during early gestation. In the other , there was associated hematoma formation early in development. According to the authors, variation in longitudinal deficiencies is likely related to the timing and duration of an insult during early limb development, and in experimental models, teratogenic insults have been shown to induce ulnar deficiencies earlier in gestation than radial deficiencies.
Nygaard et al evaluated the pressure distribution in the wrist joints with ulnar shortening and lengthening and made the following findings [7] :
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Compressive forces in loaded wrists were distributed with 67% across the radiocarpal joint and 33% across the ulnocarpal joint
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Shortening the ulna by 3 mm increased load in the radius to 80%
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Lengthening the ulna by 1 mm increased its load to 55%
In addition, they noted that load share of the distal radioulnar joint was constant even when the ulna was shortened 3-4 mm. [7] They therefore suggested shortening the ulna by 3 mm, since the increased load in the related joints are constant within a range of –2 to –4 mm.
Etiology
Most cases of ulnar deficiency of the forearm are sporadic in occurrence, though genetic syndromes are associated with ulnar dysplasia.
Focal dermal hyperplasia, or Goltz syndrome (also known as Goltz-Gorlin syndrome), is an X-linked dominant condition that consists of ulnar dysplasia, long-bone defects, and split-hand or split-foot, with skin atrophy; anal, vulval, or lip papillomata; microphthalmia; iris coloboma; and mental retardation. [8, 9, 10, 11, 12] Split-hand and split-foot with ulnar dysplasia have an autosomal dominant inheritance. [13] An ulnar defect with mammary gland aplasia syndrome is associated with polydactyly or camptodactyly. [14]
