Congenital syndactyly, also known as “webbed fingers”, is a congenital connection of two or more fingers, and is one of the most common congenital malformations of the hand, with half of the children having bilateral syndactyly and about 10% having a family history of syndactyly. In the case of the family history of syndactyly, the middle and ring fingers are often joined, and there are 2 or 3 toes joined.
Syndactyly is a disorder of partial differentiation of the limb. The outline of the fingers begins to appear at the end of the upper limb bud at the 4th week of life, and the fingers are clearly differentiated at the 8th week. At 7 to 8 weeks of life, the embryo is slightly injured, causing a partial arrest of finger differentiation and impaired differentiation of the palmar plate. Most are autosomal dominant.
Typing.
(1) Structural typing according to the syndactyly tissue
(1) Simple syndactyly: only the skin and connective tissue of adjacent fingers are connected, and the skin between the fingers is of different widths, and the X-ray shows clear boundaries between the syndactyly, so it is also called soft tissue syndactyly.
②Complex syndactyly: In addition to continuous skin and soft tissue connection between two or more fingers, there is also fusion between finger bones, or neurovascular and muscular tendon connection, so it is also called bony syndactyly.
(2) Classification according to the degree of juxtaposition
①Complete syndactyly: from the base of adjacent fingers to the tip of the finger is completely connected.
(2) Incomplete syndactyly: only part of the tissues of the adjacent fingers are connected.
③Composite syndactyly: the syndactyly is combined with other deformities, such as acral syndactyly, short syndactyly, split syndactyly, multifidus syndactyly, and annular sulcus syndactyly, etc.
Clinical manifestations.
The clinical manifestations of syndactyly are various, in the form of either cutaneous soft tissue syndactyly or bony syndactyly with bones fused together. It is often manifested as a two-finger syndactyly, but there are also three-finger or four-finger syndactyly, or even five-finger syndactyly. Ring finger syndactyly is the most common (50%), followed by ring little finger (30%), show middle finger (15%), thumb and show finger syndactyly is rare (5%), about half of the children have bilateral syndactyly.
Treatment.
The goal of surgical correction of congenital syndactyly is to establish a satisfactory finger web shape and to avoid secondary flexion contracture of the fingers. Since infants and young children have difficulties in flap design and implantation and postoperative fixation due to the short fingers, the following principles are generally followed for specific surgery.
1. Timing of surgery The timing of treatment for syndactyly should be based on the form and degree of syndactyly, the general health condition of the child, the safety of anesthesia and the parents’ requirements. The development of the child’s fingers is accelerated after early surgery, and the residual deformity is obvious after later surgery.
(1) For those syndactyly with joints not at the same level, affecting the flexion and extension of the fingers, and those with fused terminal phalanges, which will affect the development and function of the fingers if not separated in time, surgery can be performed at 18 months of age.
(2) For syndactyly that does not cause developmental deformity, surgery can be performed at the age of 3-4 years.
(3) Multiple fingers should be operated in stages to prevent vascular malformation and necrosis of the separated fingers.
(2) Thorough finger splitting The finger splitting procedure should be performed to completely separate the fingers from each other to the normal finger web base. If the flippers are not completely separated, the fingers will still be partially joined. A normal finger web should have a sloping skin fold of considerable width and length, covering 1/3-1/2 of the length of the proximal phalanges.
In a normal adult, the finger webs are sloped from the distal dorsal side of the metacarpal head to the metacarpal side and are attached to the metacarpal skin at the transverse palmar finger line. There are many finger flippers reconstruction methods, but the rectangular flap method is more physiological and has good results.
4. Serrated incision and skin grafting The skin between the split fingers should be made into a serrated incision, avoid making a straight incision, otherwise, a straight scar contracture of the skin will be formed. When designing the serrated flap, the site of the flap should be designed according to different situations, and usually the flap should cover the joint area as much as possible. The trauma after the merging and splitting of fingers should not be closed forcibly under tension, but need to be transplanted with full-thickness skin flaps to avoid causing increased scar widening or local skin necrosis, or even total finger necrosis.
5, the end finger bone fusion of the parallel fingers In separating the end joint, it is necessary to cut a skin flap and a subcutaneous tissue fascial flap locally in the finger belly at the same time, and stagger each other, covering the two bony exposed traumas respectively, pay attention to their blood circulation; then implant the skin on the subcutaneous tissue flap, the pressure packing force should not be too large, so as to avoid excessive pressure causing necrosis of the fascial flap. The end bone exposure needs to be covered by local flap, and if there is soft tissue covering around it, it can also be repaired by skin grafting.