Congenital triphalangism of the 1st finger of the hand: causes, symptoms, diagnosis, treatment

Congenital trephalangeism of the first finger of the hand is a developmental defect, in which the thumb (like the rest of the fingers of the hand) has three phalanges.

ICD-10 code

• Q74.0 Congenital trephalangeism of the first finger.

Symptoms and Diagnosis of Congenital Three-phalanx I of the Finger Brush

The main features that allow differentiating different forms of this defect: the longitudinal dimensions of the first metacarpal bone and the location of its epiphyseal growth zone; the size and shape of the additional phalanx: the longitudinal dimensions of the first ray of the hand: the size of the first interstitial space: the state of the muscles of thenar, the function of the brush. On the basis of these criteria, the following variants of congenital tri-phalanism of the first finger of the hand are distinguished: a simple form (brachimezophalangeal, pseudo-triphalangism, dolichophalangeal) and a complex form (in combination with hypoplasia of the first ray or with radial polydactyly).

In X-ray examination, pseudotrophans is characterized by the presence of an enlarged epiphysis of the distal phalanx of a trapezoidal or rectangular shape simulating an additional phalange of the 1st finger. Clinically, the ulnar clinodactyly at the level of the interphalangeal joint of the thumb, the function of the brush is preserved. The brachimezophalangeal form is characterized by the presence of an additional phalanx whose dimensions are less than or equal to the distal phalange; its shape depending on the degree of severity of the defect may be triangular, trapezoidal or rectangular; the dimensions of the first ray of the brush are close to normal or significantly enlarged. The muscles of the elevation of the thumb are normal, but they can be hypoplastic. The two-sided hand grip function is retained or sharply limited. The dolichophalangeal form of congenital triphalangism of the first finger of the hand is manifested by an increase in the longitudinal dimensions of the first ray of the hand; the dimensions of the additional phalanx are greater than the dimensions of the distal phalanx (it has a rectangular shape): a significant narrowing of the first interstitial space; pronounced hypoplasia of the muscles thenar, the function of bilateral grasp of the hand is absent or sharply limited.

Treatment of congenital trephalangeism of the first finger

The technique of the operation depends on the shape of the three-phalanx. The age of the child, the size of the additional phalanx and the first ray as a whole relative to the age norm, as well as the degree of underdevelopment of the thenar muscles .

In the presence of an average phalanx of triangular shape in children under 2 years old it is removed and the capsular-ligamentous apparatus of the joint is reconstructed. In children older than 2 years, and also when the additional phalanx has a trapezoidal or rectangular shape, the best result is a wedge resection of the phalanx with simultaneous elimination of one of the interphalangeal joints.

In cases of pseudothelophangia, the corrective osteotomy of the epiphysis of the primary phalanx of the first finger is performed by wedge resection. With a fraction-hophalangeal form, the operation of choice is considered to be the pollicization of the thumb of the hand. When a brachime mesophalangeal form of three-phalanx and hypoplasia of the first ray is combined, the thumb is placed in the position of the opposition with simultaneous resection of one of the interphalangeal joints. With dolichophalangeal form with hypoplasia, the phalanx of the thumb and retained opposition perform a resection of the interphalangeal joint, at the level of which deformation was noted. With hypoplasia of the entire first ray and the muscles of the thenar, a pollicization operation is performed, which (if necessary) is combined with resection of one of the interphalangeal joints or with the elimination of the flexion contracture of the thumb. When combining three-phalanx with radial polydactyly, simultaneously with the removal of additional segments, resect the most hypoplastic interphalangeal joint (with brachimezoph-langal form) or a pollicization operation (with dolichophalangeal form).

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