Ulnar dysplasia also known as ulnar longitudinal deficiency, ulnar club hand or ulnar aplasia/hypoplasia is a rare
congenital malformation
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can r ...
which consists of an underdeveloped or missing
ulnae bone, causing an ulnar deviation of the entire wrist. The muscles and nerves in the hand may be missing or unbalanced. In severe cases, ulnar digits (e.g. ring and pinky finger) may be missing. Sometimes,
radial dysplasia
Radial dysplasia, also known as radial club hand or radial longitudinal deficiency, is a congenital difference occurring in a longitudinal direction resulting in radial deviation of the wrist and shortening of the forearm. It can occur in different ...
occurs alongside this malformation. This condition occurs in 1 in 100,000 live births. Sometimes, other orthopedic problems occur alongside this malformation, such as
scoliosis
Scoliosis is a condition in which a person's spine has a sideways curve. The curve is usually "S"- or "C"-shaped over three dimensions. In some, the degree of curve is stable, while in others, it increases over time. Mild scoliosis does not t ...
.
Types
There are four types of ulnar dysplasia:
Type 1: The mildest type of ulnar dysplasia. The ulnae is slightly shorter than average and there is a barely noticeable wrist deviation
Type 2: The ulnae is moderately-severely smaller than normal. The
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
is deviated and so is the hand
Type 3: The ulnae is completely missing. The
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
is even more deviated, causing a severe ulnar deviation of the hand.
Type 4: The most severe type of ulnar dysplasia, the ulnae is completely missing, and the wrist is severely deviated. The elbow bones are fused together, so the elbow has
reduced mobility
See also
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Radial dysplasia
Radial dysplasia, also known as radial club hand or radial longitudinal deficiency, is a congenital difference occurring in a longitudinal direction resulting in radial deviation of the wrist and shortening of the forearm. It can occur in different ...
*
Ulnar nerve entrapment
Ulnar nerve entrapment is a condition where the ulnar nerve becomes physically trapped or pinched, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point from ...
References
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Genetic diseases and disorders