Orthopaedic Surgery - Syndactyly

Basics

Syndactyly is a congenital condition characterized by:

Webbing or fusion of adjacent fingers or toes.

It is usually evident:

At birth.

Synonym

Another term is:

Webbed digits.

Classification

Syndactyly can be classified according to:

The tissues involved

and

The extent of fusion.

Simple Syndactyly

Simple syndactyly involves fusion of:

Skin and soft tissue only

without underlying:

Bony fusion.

Complex Syndactyly

Complex syndactyly includes abnormalities involving:

Bone

Joint

or other deeper structures.

The adjacent bones may be partially or completely:

Fused.

Complete Syndactyly

Complete syndactyly extends along essentially the:

Entire length of the involved digits

to the:

Fingertips.

Incomplete Syndactyly

Incomplete syndactyly involves only a:

Portion of the digit length

with separation present distally or proximally.

Fenestrated Syndactyly

Fenestrated syndactyly describes digits that are:

Separated proximally

but remain joined:

Distally.

Epidemiology

Syndactyly is one of the more common congenital:

Hand abnormalities.

Incidence

It occurs in approximately:

1 in 2,000 live births.

Bilateral Involvement

Approximately:

50% of cases

involve both:

Hands or feet.

Sex and Population

Historical studies have reported syndactyly more frequently in:

Males

and in:

White populations.

Risk Factors

The presence of other congenital abnormalities may increase the likelihood that syndactyly is part of a:

Recognizable syndrome.

Genetics

Most cases are:

Sporadic.

Approximately:

10–40%

have been reported to show a:

Familial pattern.

Sporadic Cases

Historical series suggest that up to approximately:

80%

of cases occur without an obvious:

Family history.

Inheritance

Familial syndactyly can demonstrate:

Autosomal dominant inheritance

in some families, although inheritance depends on the specific:

Syndrome or genetic subtype.

Etiology

Syndactyly results from failure of normal:

Separation of adjacent digits

during embryologic development.

Embryology

Finger and toe separation normally occurs during approximately the:

Sixth to eighth weeks of gestation.

Failure of programmed tissue separation during this period produces:

Persistent webbing.

Cause

In most isolated cases, the precise cause is:

Unknown.

Isolated Versus Syndromic Disease

Syndactyly may occur:

As an isolated congenital abnormality

or as part of a:

Genetic or congenital syndrome.

Most cases are:

Isolated.

Associated Conditions

Conditions associated with syndactyly include:

Apert syndrome

Poland syndrome

Congenital constriction band syndrome

and selected other:

Genetic disorders.

Apert Syndrome

Apert syndrome is characterized by:

Craniosynostosis

and severe:

Complex syndactyly

of the hands and feet.

It has historically been termed:

Acrocephalosyndactyly.

Poland Syndrome

Poland syndrome may include:

Absence or hypoplasia of the pectoralis major muscle

with ipsilateral:

Upper-extremity abnormalities

including:

Syndactyly or brachydactyly.

Congenital Constriction Band Syndrome

Amniotic or congenital constriction bands may produce:

Syndactyly

Distal swelling

Digital deformity

or even:

Amputation.

Neurofibromatosis

Some historical reports describe a slightly increased occurrence of syndactyly with:

Neurofibromatosis

although this is not among its major defining features.

Diagnosis

Diagnosis is usually made by:

Physical examination at birth.

Imaging helps determine whether the condition is:

Simple or complex.

Signs and Symptoms

Syndactyly itself is generally:

Painless.

Functional limitation depends on:

Which digits are involved

and the degree of:

Soft-tissue or bony fusion.

Physical Examination

The examination should assess:

Extent of webbing

Digit length

Joint motion

Independent movement

Nail development

and associated:

Congenital abnormalities.

Joint Motion

Evaluate both:

Active

and

Passive range of motion

at each joint of the involved digits.

Independent Digital Movement

Ask the patient, when developmentally able, to move the two involved digits:

Separately.

Independent motion suggests that major:

Bony fusion

or extensive tendon interconnection is less likely.

Skin Availability

The amount of available skin between the digits is important for planning:

Surgical reconstruction.

A deficiency of local skin may increase the need for:

Skin grafting.

Nail Examination

Inspect the nails for:

Separate nail plates

or

Nail fusion.

Joined nails may suggest more extensive:

Distal skeletal involvement.

Rotational and Angular Deformity

The surgeon should assess for:

Rotation

Angular deformity

and unequal:

Digit length.

These findings may complicate:

Reconstruction.

Imaging

Plain Radiographs

Radiographs are useful for distinguishing:

Simple syndactyly

from

Complex syndactyly.

Radiographic Findings

Imaging can identify:

Bony fusion

Abnormal phalanges

Joint abnormalities

and differences in:

Digit length or alignment.

Vascular Imaging

In difficult complex cases, evaluation of the:

Digital vascular anatomy

may occasionally be required.

MRA or Angiography

MR angiography or conventional angiography may help define:

Neurovascular branching patterns

when standard anatomy is uncertain.

Distal Vascular Bifurcation

If the shared digital artery divides:

Very distally

separation may threaten the blood supply to one of the:

Digits.

This can limit how completely the digits can be:

Separated.

Pathological Findings

Syndactyly may be associated with:

Insufficient skin

between the involved digits.

Fascial Abnormalities

There may be abnormal connections between:

Fascial planes.

Tendon Interconnections

The:

Flexor

and

Extensor tendons

may have abnormal cross-connections between:

Adjacent digits.

Bone and Joint Abnormalities

Complex cases may demonstrate:

Fused phalanges

Abnormal joints

Delta phalanx

or other congenital:

Skeletal abnormalities.

Differential Diagnosis

The major diagnostic distinction is between:

Simple

and

Complex syndactyly.

Other congenital conditions that may resemble or accompany digital fusion include:

Constriction band syndrome

Symbrachydactyly

and syndromic:

Hand malformations.

Treatment

Treatment depends on:

Digits involved

Severity

Functional limitation

Growth asymmetry

and whether the syndactyly is:

Simple or complex.

General Measures

Not every syndactyly requires:

Surgery.

Mild Webbing

Minor incomplete webbing that causes little functional or cosmetic concern may be managed with:

Observation.

Goals of Release

Surgical separation may improve:

Finger independence

Grasp

Pinch

Digit growth

and

Cosmetic appearance.

Border Digits

Syndactyly involving digits of substantially different lengths can lead to:

Growth tethering

and secondary:

Angular deformity.

This is particularly important for:

Thumb-index

and

Ring-small finger syndactyly.

Timing of Surgery

Timing depends on which digits are involved and the complexity of:

The deformity.

Border-Digit Syndactyly

For border digits, release is often performed after approximately:

6 months of age

because unequal digit lengths may produce progressive:

Growth distortion.

Central-Digit Syndactyly

For central digits, surgery is commonly delayed until approximately:

12 months of age

or later when there is less urgency related to:

Growth imbalance.

Complex Cases

Complex syndactyly may require earlier or staged treatment depending on:

Bone fusion

Nail abnormalities

Digit length discrepancy

and

Vascular anatomy.

Physical Therapy

Formal therapy is usually:

Not required before surgery.

Postoperative Therapy

Hand therapy may be useful for:

Scar management

Web-space splinting

and

Range-of-motion exercises.

Surgery

The operative technique depends on:

Extent of webbing

Skin availability

Bony involvement

and

Vascular anatomy.

Web-Space Reconstruction

A properly shaped commissure or web space must be created to reproduce the normal:

Interdigital cleft.

Dorsal Flap

For simple syndactyly, a broad:

Dorsal commissural flap

is commonly used.

The flap is designed with a wider:

Proximal base

to preserve:

Blood supply.

Zigzag Incisions

Interdigitating:

Z-plasty or zigzag skin incisions

are frequently used along the digits.

These reduce the risk of:

Linear scar contracture.

Skin Grafting

After separation, there is often insufficient local skin to cover both digits completely.

Therefore:

Full-thickness skin grafting

may be necessary.

Graft Donor Sites

Potential donor sites include:

Groin

Wrist crease

or other areas providing suitable:

Full-thickness skin.

Graft-Free Techniques

Some modern techniques use local flaps designed to minimize or eliminate the need for:

Skin grafts

in selected simple cases.

Complex Syndactyly

When bones are fused, surgical treatment may require:

Bony separation

in addition to:

Soft-tissue reconstruction.

Tendon and Ligament Reconstruction

Abnormal:

Tendon

Ligament

or

Joint structures

may also need to be:

Reconstructed.

Neurovascular Considerations

Each separated digit must retain an adequate:

Digital artery

and intact:

Digital nerve supply.

Staged Release

When three adjacent digits are joined, separation is often performed in:

Stages.

This helps preserve at least one intact:

Neurovascular bundle

on each side of a digit during healing.

Postoperative Dressing

Postoperative dressing is a critical part of:

Treatment.

Immobilization

The hand and arm may be immobilized in a:

Bulky protective dressing

with or without an:

Above-elbow cast.

Duration of Dressing

The initial protective dressing is commonly maintained for approximately:

2–3 weeks

depending on:

Wound healing

and surgeon preference.

Follow-Up

Patients require follow-up to assess:

Wound healing

Skin graft survival

Digit perfusion

and

Web-space shape.

Long-Term Follow-Up

As the child grows, monitoring should continue for:

Scar contracture

Web creep

Angular deformity

and recurrent:

Syndactyly appearance.

Prognosis

The prognosis after appropriate treatment is generally:

Good.

Cosmetic Outcome

Minor differences in:

Finger width

Nail shape

Skin appearance

or

Web depth

may remain after reconstruction.

Functional Outcome

Most children achieve useful:

Independent finger motion

and improved:

Hand function.

Complications

Potential complications include:

Stiffness

Wound dehiscence

Scar contracture

Partial web recurrence

and rare:

Vascular compromise.

Web Creep

One of the more common long-term complications is:

Web creep.

This refers to gradual distal migration of the reconstructed:

Web space

as the child grows.

Scar Contracture

Linear or hypertrophic scars can produce:

Contracture

and restrict:

Finger motion.

Wound Dehiscence

Separation of the surgical wound can occur, particularly when:

Skin tension

is excessive.

Digital Stiffness

Complex reconstruction may occasionally result in loss of:

Joint motion.

Circulatory Compromise

Damage to shared digital vessels can cause:

Ischemia

and in severe cases:

Loss of the digit.

This complication is:

Rare.

Prevention of Vascular Injury

Risk can be reduced by carefully preserving at least one:

Collateral digital vascular supply

and avoiding simultaneous release on both sides of a digit when this would endanger:

Perfusion.

Patient Monitoring

Children should be monitored throughout growth for:

Web creep

Scar contracture

Joint stiffness

Digit angulation

and evolving:

Functional limitation.

Key Principle

Syndactyly is a congenital failure of separation of adjacent digits during approximately the sixth to eighth weeks of embryonic development.

It may be:

Simple or complex

and

Complete or incomplete.

Most cases are isolated, although syndactyly may occur with conditions such as:

Apert syndrome, Poland syndrome, or congenital constriction band syndrome.

Surgical release is performed when the deformity affects:

Function, growth, or appearance, with earlier treatment often preferred for border digits because unequal digit lengths may cause progressive:

Angular deformity.

Successful reconstruction requires careful management of:

Skin coverage, neurovascular anatomy, web-space formation, and postoperative scar control.