Ulnar longitudinal deficiency
Ulnar deficiencies are rare congenital malformations in which there is a longitudinal failure of the formation along the post-axial border of the upper extremity.
The most common form of ulnar deficiency is a partial deficiency of the ulna and ulnar to digits.
It is commonly referred to as the ulnar club hand. Other terms are ulnar dysmelia, paraxial ulnar hemimelia, and congenital absence of the ulna.
The cause of ulnar deficiency is unknown.
Usually, ulnar deficiency occurs sporadically.
Associated musculoskeletal anomalies include proximal femoral focal deficiency, fibular deficiency, phocomelia, scoliosis, spina bifida, mandibular defect, and absence of patella.
Children with ulnar deficiency have hypoplasia of the entire upper extremity.
Elbow is malformed or fused i.e. radiohumeral synostosis in a majority of cases.
Ulna may be partially or completely absent and a cartilage ulnar anlage may be present.
Hand and carpus are always affected – 90% missing digit, 70% thumb abnormality, and 30% syndactyly.
Unilateral ulnar deficiency is more common than bilateral deficiency.
Radiographs are required to determine the extent of the deficiency.
Radiographs of both the upper extremity and spine should be taken.
Magnetic resonance imaging will aid in identifying the cartilage anlage.
The most important functional gains are achieved by operating on the hands rather than forearm or wrist.
In the hand, syndactyly release and first web contracture release are first stage operation.
Early stretching and splinting of the ulnar deviated wrist is advised when the wrist deviated more than 30 degrees.
Surgical release of the ulnar anlage is advised when there is a deviation of more than 30 degrees and there is evidence of progression of the deformity.
Forearm surgeries are deferred till adolescent age when the instability can be assessed properly and one bone forearm is an option.
Elbow surgeries include osteotomy through the synostosis and radial head excision.
The long term consequences are a progressive ulnar deviation of wrist, deformity and functional limitation of the hand.