Syndactyly in children

In short: syndactyly is the failure of separation of two or more fingers, present from birth. It is one of the most common congenital hand differences. Treatment is surgical and is performed in a paediatric hand surgery centre; the timing of surgery is not the same for everyone but depends on which digits are involved and on the type of fusion.

In short

The clinical distinction rests on two axes:

• simple or complex: in the simple form only skin and soft tissues are joined; in the complex form there is also a bony fusion between the phalanges. Complicated forms also exist, with supernumerary bones or markedly altered anatomy;
• complete or incomplete: in the complete form the union extends to the fingertips; in the incomplete form it stops earlier, at a variable level.

To these is added the clinically most relevant information: which digits are involved. Digits of very different length growing joined together — such as thumb and index, or ring and little finger — tend to deviate progressively with growth, and this influences when surgery is undertaken.

Symptoms and when to worry

Syndactyly is recognised at birth. In incomplete forms between digits of similar length, hand function may be substantially preserved and the child develops an effective grasp. In complete forms or between digits of different length, shared growth can lead to progressive deviation and functional limitation.

Signs prompting earlier assessment: increasing deviation of the digits, evident difficulty with grasp, hygiene problems or skin maceration between the digits, and any suspicion of forms associated with syndromes or anomalies elsewhere.

Diagnosis and imaging

Assessment is clinical: the digits involved, the level and type of fusion, the presence of separate or shared nails, joint mobility and grasp function are all defined. A hand X-ray distinguishes simple from complex forms, documenting bony fusions and supernumerary bones. In pictures with other clinical signs a genetic assessment may be indicated, and is proposed only when the overall picture justifies it.

Treatment

There is no conservative treatment that separates the digits: treatment of syndactyly is surgical. The operation involves separating the digits, reconstructing the web space (commissure) and covering the skin, which often requires skin grafts because the surface to be covered after separation exceeds the skin available.

Timing is individualised. A shared practical principle is to operate earlier on syndactyly between digits of very different length, because shared growth tends to produce progressive deviation, and later on the others. Syndactyly involving several adjacent spaces is generally addressed in more than one operation, so as not to compromise the blood supply to the digits. Quoting a single age valid for everyone would be a simplification: planning takes into account the digits involved, the type of fusion, skin condition and the child's general status.

This surgery is performed in paediatric hand surgery centres. Dr Priano provides the orthopaedic assessment, guidance for the family within the pathway and the follow-up, not the performance of the operation.

Follow-up and recovery

The postoperative course involves a protective dressing, a period of immobilisation and subsequently hand therapy and, in many cases, scar splinting or pressure therapy. Follow-up continues for years, throughout growth.

Two aspects should be known in advance: the scar may require dedicated treatment and can become hypertrophic, and web creep — distal migration of the reconstructed commissure during growth — is a known complication that in a proportion of cases makes revision surgery necessary. It is not an unexpected failure but an eventuality to be accounted for from the outset. See also the other congenital hand differences: clinodactyly, camptodactyly and congenital clasped thumb.