Kirner's deformity
Medical condition
From Wikipedia, the free encyclopedia
Kirner's deformity, also known as dystelephangy, is an uncommon genetic hand malformation which is characterized by a radial and volar curvature of the distal phalange of the fifth (pinky) finger. It is merely cosmetic and doesn't affect hand function.[2]
| Kirner's deformity | |
|---|---|
| Other names | Dystelephangy, Congenital bilateral metadiaphyseal acrodysplasia of the little finger[1] |
 | |
| This trait is often hereditary, and is thought to be inherited in an autosomal dominant manner with reduced penetrance | |
| Specialty | Medical genetics |
| Symptoms | Radial and volar curvature of the distal phalange of the fifth finger. |
| Complications | None |
| Types | There are congenital, early-onset, and acquired forms. |
| Causes | Autosomal dominant inheritance |
| Prevention | None |
| Treatment | Usually, none is required, surgery is done due to cosmetic reasons |
| Prognosis | Good |
| Frequency | Uncommon, about 1 in 400-600 people are thought to have this deformity |
| Deaths | Deaths are not involved with the deformity, since it isn't deadly. |
Etymology
This condition is considered to be a type of isolated brachydactyly.[3]
A.R. Thomas et al. described it as a "dystrophy of the fifth finger".[4]
History
This difference was first discovered in 1927 by Kirner et al., when he described a 13-year-old girl with the characteristic radial and volar curvature of the fifth finger's distal phalanx bone.[5]
Signs and symptoms
This anomaly is characterized by the painless curvature and "bulbing" of the distal end of the little finger.[6] The time of onset varies among people, but the two most common ages of onset are birth and adolescence, although there can be cases where one is already born with a Kirner's deformity that worsens as one grows older (progressive).[7]
Rarely, multiple fingers (which may or may not include the little finger) may be affected with Kirner's deformity; this is known as polytopic dystelephalangy, and cases like this typically have a strong genetic link.[8]
Other isolated congenital deformities of the hand can occur alongside this deformity; one such instance is the family described by Erduran et al., which presented both camptodactyly and Kirner's deformity.[9]
Radiological findings
The following list comprises the radiological findings associated with Kirner's deformity that have been described in medical literature:[7][10][11]
- Diaphyseal shortening
- Diaphyseal curvature
- Epiphyseal curvature
- Sclerosing of the diaphyses
- Agenesis of the little finger's flexor digitorum superficialis tendon
- Abnormal cartilage placement of the diaphyses and the flexor tendon
- Radiolucent nidus in the little finger's distal tuft
- L-shaped physis
Causes
This deformity is caused by a widening of the epiphyseal plate of the fifth finger's distal phalange.[12] Another proposed cause involves the abnormal insertion of the flexor digitorum profundus in the volar area of the fifth finger's distal phalange.[13] It is thought to be an autosomal dominant trait with reduced penetrance.[14]
Diagnosis
This condition can be diagnosed by physical examination and radiographic imaging, including X-rays, magnetic resonance imaging, etc.[citation needed]
Differential diagnosis
This condition can be confused with other malformations (congenital and acquired) of the hand, these include:
- Camptodactyly[15][16]
- Clinodactyly[17][16]
- Mallet finger[18]
- Fracture[19]
- Brachydactyly type A3 (also known as brachymesophalangy type V)[20]
Epidemiology
This hand difference is estimated to be present in 0.15%-0.25% of the world population.[21]
It is more common in women than in men;[12] physical examination performed on people from a selected region in southern England by David and Burwood et al. found 18 individuals from 9 families with Kirner's deformity. Of these 18 individuals, 6 were men and 12 were women.[22]