Congenital longitudinal deficiency of the ulna, Ulnar clubhand
Ulnar hemimelia is a congenital ulnar deficiency of the forearm characterized by complete or partial absence of the ulna bone. Incidence is estimated at 1/100,000-150,000 live births, with a male to female ratio of 3:2. Ulnar hemimelia is unilateral in approximately 70% of cases, tends to be right-sided, and is usually incomplete and nonsyndromic. Most patients have some shortening of the forearm. The position of the hand tends to drift to the ulnar-side of the wrist. The extension of the elbow is generally limited to about 90 degrees. In severe cases, the elbow is held at about 160 degrees of flexion. Ulnar hemimelia may present with other skeletal anomalies (absence or hyperplasia of the radial digits, thumb duplication, or syndactyly) or as part of a syndrome (Poland anomaly, Goltz-Gorlin syndrome, Schinzel syndrome, Klippel-Feil syndrome or Cornelia de Lange syndrome; see these terms). Ulnar deficiency is also one of the manifestations of the femur-fibula-ulna syndrome (see this term). The etiology of ulnar hemimelia remains unknown. The deformity is believed to develop between the 4th and 7th week of gestation. Most of the reported cases are sporadic but a few familial cases have been described. Diagnosis is based on clinical examination and X-rays. Further tests may be required in case of additional anomalies. The differential diagnosis should include a short ulna, dyschondrogenesis, Madelung deformity, Nievergelt syndrome and embryofetopathy due to maternal diabetes mellitus (see these terms). Treatment depends on the severity of the condition and the associated skeletal anomalies or syndromes. Passive stretching exercises may allow extension of the wrist and elbow to a normal position. Corrective casting and splinting may also be used. In severe cases, surgical therapy aimed at ulnar lengthening (surgical excision, osteotomy, or plastic surgery) is necessary. Occupational and physical therapy is mandatory. Patients with ulnar hemimelia may have limited motion, function and strength, but in general, the limb and hand are functional. In case of syndromic presentation, prognosis depends on the nature of the associated anomalies.