Clinodactyly

Clinodactyly has been defined as angular deformity of the fingers in a radio-ulnar or coronal plane. It is a rare congenital condition, usually presenting in the fifth finger (little finger) or second finger (Catel Manzke Syndrome). The deformation usually occurs in the middle phalanx because it presents a triangular morphology at the distal interphalangeal joint., causing the angulation of the fingers.

Clinodactyly usually occurs because the middle phalanx of the little finger does not grow normally during development at a prenatal stage. In addition, it may be caused by an abnormal gene that is passed from parent to child (Mendelian inheritance or genetic inheritance). It is a minor birth defect, 1-3% of healthy babies have this defect.

In certain cases of clinodactyly, it is sometimes referred to as brachydactyly type A3

Usually it occurs in both hands and in certain cases it presents with a dysfunction of the affected finger.

Epidemiology

Clinodactyly as a genetic disease presents with a hereditary pattern, however, other causes cause the appearance of this minor defect in youth and even in adulthood. It usually appears on the fifth finger. Based on studies in different populations, it is assumed that clinodactyly occurs more frequently along with other syndromes. It has been seen that it is a congenital defect that occurs before childbirth or after. Studies show that clinodactyly is most frequently reported bilaterally. Within the Japanese population, clinodactyly occurs in 21% of children. It also occurs in 1% of normal live births. Studies carried out in the Guatemalan population, clinodactyly in newborns occurred in 2.09%, along with other congenital defects, clinodactyly also occurred in 1.53% in female newborns. According to a study carried out in China by Dr. F. J. Tsai, it is assumed that 4% of the population presents clinodactyly.

It is more frequent in boys than in girls, and it also occurs much more frequently in children with a family history of the disease. Likewise, clinodactyly is the most frequent post-surgery complication, however, its presence is rare. more of an aesthetic problem than a functional one.

Clinodactyly is associated with a number of congenital defects, which is why 60% of newborns with Down syndrome present a lack of development in the second phalanx of the fifth finger of the hand. With the use of studies non-invasive complementary tests of excess to the fetus, the second trimester ultrasound is the most indicated, since it shows hypoplasia and clinodactyly present in the fifth finger.

Clinodactyly occurs in the index finger with the formation of an accessory bone, in the metacarpophalangeal joint, which gives rise to a radial deviation of said finger. Likewise, in type I orofaciodigital syndrome, it presents skeletal abnormalities such as clinodactyly (47.4%), syndactyly (49.6%), preaxial (19.3%) or postaxial (3.7%) polydactyly and low height (7%).

Genetics

Clinodactyly can present a hereditary pattern, it is related to an autosomal recessive genetic alteration, as well as variable genetic expression and incomplete penetrance (incomplete expression of a dominant character), known as familial clinodactyly.

Being autosomal recessive, it presents the following characteristics:

• It appears in a single generation (horizontal tolerance)
• Both sexes are equally affected.
• The carrier couple has a 25% chance of having affected offspring.
• Frequent in parental consanguinity.

Studies reveal that the cause of clinodactyly is generally related to Catel Manzke syndrome, because the TGDS segment (13q32.1) is responsible for the appearance of this congenital defect.

Clinodactyly occurs much more frequently in patients with Pierre Robin Syndrome, characterized by an unusually small jaw (micrognathia), retraction of the tongue (glossoptosis), and cleft palate.

In addition, clinodactyly may be associated with severe cases of Down Syndrome, Apert Syndrome, Rubinstein-Taybi Syndrome, Klinefelter Syndrome and Edwards Syndrome, as well as being common in Fetal Alcohol Syndrome.

In addition, it is associated with other syndromes such as:

• Proximal segment partial trisomnia
• Mieller Dieker Syndrome
• Aarskog syndrome
• Pfeiffer syndrome
• Saethre-Chotzen Syndrome
• Seckel syndrome
• Silver-Russell Syndrome
• Syndrome Lange

Genetic causes

The etiology of clinodactyly is unknown, however, it can vary genetically. In addition, clinodactyly is one of the fetal markers of the second trimester, so the presence of this deviation on ultrasound may indicate a congenital anomaly present in the fetus, such as Down Syndrome, this sign being useful for its diagnosis.

Congenital clinodactyly present in different ways, such as:

• Clinodactilias isolated: is presented as a loss of parallelism between the interfalangic joints, without being associated with other growth plate anomalies. The consequences on development are few and surgical intervention is not necessary.

• Clinodactilia due to a delta phalange: There is the presence of a trapezoid phalange which has an epiphysis in the form of “C”. The epiphysis that presents the additional phalange grows at less speed, which causes angular deformity.

Other causes

Clinodactyly, in addition to being autosomal recessive, can also present or be acquired through fractures, trauma to the upper limb (hand), playing sports such as Pelotari, chronic juvenile polyarthritis or frostbite.

Diagnosis

Clinodactyly may not be very evident in the first weeks of gestation, however, the diagnosis is made at birth based on clinical evaluation, as well as identifying characteristic physical findings that confirm the presence of clinodactyly in newborns born.

In addition, through a physical examination it is important and very useful to diagnose the presence of this condition. It can also be diagnosed through genetic counseling, through which a geneticist can help detect a familial clinodactyly and also rule out other associated abnormalities and syndromes that may affect the functioning of the upper limbs, that is, the hand.

During the physical examination, specialists have managed to diagnose using a ratio, which is the length of the middle phalanx of the 5th finger/length of the middle phalanx of the 4th finger, with the study some researchers have determined an average value of the proportion for healthy fetuses and those with Down syndrome of 0.85 and 0.59 (p=0.04), respectively. When using a cutoff ratio of 0.7, the sensitivity for fetal Down syndrome was 75%, with a false positive rate of 18%.

Treatment

Clinodactyly is a minor congenital defect, so it does not need to be treated urgently, except when this defect causes discomfort or affects the normal functioning of the upper limb, in which case the hand.

Treatment for clinodactyly can be of two types: observation and non-surgical. However, if the clinodactyly presents severe deformities, the best treatment will include surgery. The technically demanding. The most frequently performed procedures for the correction of angular deformities seen in clinodactyly are: bar removal, corrective osteotomies, and growth plate removal.Surgical procedures often have With good prognoses, the chances of clinodactyly recurring are rare.

Surgical intervention is as follows:

• Reaxation Osteotomies
• Cuneiform osteotomy of subtraction. Extraction of the additional bone part in order to return the finger to normal position. It is recommended in the older child or adolescent.
• Opening cuneiform osteotomy. Reserved to young children. Surgical intervention on the opposite side of deformity. This simple non- grafting technique allows for consolidation within normal early childhood periods (3-5 years).
• Interventions of "despifisiodesis". It consists of a progressive remodeling of deformity thanks to growth. It targets only the early diagnosed delta phalanges.