Macrodactyly

Disproportionately large digit noted at birth or that develops within 1^st year of life.

Both soft tissue and skeletal elements are enlarged

(Other descriptive terms that are used – megalodactyly, gigantism, macrodystrophia, lipomatosa, macrodactylia fibrolipomatosis)

 

It is uncommon – incidence – 0.9%

Most cases are sporadic. No evidence of inheritance.

Most common form – isolated anomaly with lipofibromatosis of proximal nerve.

It can occur in association with other anomalies

 

Flatt’s classification

Type 1 – gigantism and lipofibromatosis

Type 2 – gigantism and neurofibromatosis

Type 3 – gigantism and digital hyperostosis

Type 4 – gigantism and hemihypertrophy

[Fat-Nerve-Bone-Limb]

Most common is- Type 1.

 

Type 1 –

Macrodactyly a/w enlarged nerve infiltrated with fat within digits and extending proximally through carpal tunnel

Type 2 –

1. Macrodactyly with plexiform form of NF and is often bilateral
2. There may be osteochondral mass a/w skeletal enlargement

Type 3 –

1. Osteocondral periarticular masses developing in infancy.
2. No significant nerve involvement.
3. Digits are nodular and stiff and other skeletal anomalies can be seen.
4. Rare type

Type 4 –

1. Rare
2. All digit involved but less severe than type 1 & 2
3. Intrinsic muscle hypertrophy or abnormal intrinsic anatomy
4. Deformity present with flexion contracture, ulnar deviation and adducted thumb deformity.

 

[Bilateral involvement – type 2]

[No nerve involvement – type 3]

[Intrinsic muscle involvement – type 4]

[Contracture – type 4]

 

Macrodactyly a/w lipofibromatosis –

Noted at birth or within 3 yrs

Growth of affected digits is disproportionate – progressive macrodactyly

Growth may be in consistent proportion with rest of hand – static macrodactyly

Usually unilateral

May affect more than one digit

Multiple digit involvement is 2-3 times more common than single digit involvement.

Most common affected finger – Index (a/w long finger or thumb)

Radial digits deviated radially

Ulnar digits deviates ulnarly

If two digits involved then they deviate divergent.

Enlarged thumb are typically – abducted and extended.

Osseous growth and deviation stops after physeal closure, but soft tissue continues to enlarge.

Radiograph – enlarged skeleton with

1. Advanced bone age
2. Abnormal digits and deviation
3. Osteoarthritic changes

Soft tissue swelling may be present – signifying underling nerve fatty infiltration.

Compression neuropathy may result

Thickening of flexor sheath – may result in trigger finger

Syndactyly seen in – 10% cases.

 

Macrodactyly a/w neurofibromatosis –

Shows typical skin features of NF 1 (Café-au-lit spots, multiple neurofibroma, peducalated skin tumors and ocular lesions)

 

Hyperosteotic macrodactyly –

Rare

Nodular enlargement of digit and profound loss of motion secondary to periarticular osteochondral mass formation

Radiology confirms diagnosis – showing periarticular osteochondral masses.

 

Macrodactyly can be part of a broader gigantism –

Segmental gigantism – affecting only a part of one limb

Hemihypertrophy – affecting one side of body (a/w NF or KTS)

 

Other syndromes a/w digital enlargement –

1. Ollier disease
2. Maffuci syndrome
3. KTW syndrome
4. Proteus syndrome

 

Pathophysiology

Not known

Possible explanation – nerve territory oriented macrodactyly

Abnormal nerve supply leading to unimpeded growth (most cases occur in single digit or in a region supplied by a single nerve)

Other theories – an increase in blood supply and/or an abnormal humoral mechanism stimulating growth.

 

Macroscopic finding –

1. Increased subcutaneous fat
2. Enlarged tortuous digital nerve
3. Skeletal overgrowth in all direction
4. Palmar aspect is more affected than dorsal
5. Distal finger is more affected than proximal
6. Flexor sheath may be thickened
7. Tendons are normal

 

Histology –

1. Thickening of skin with decreased sweat gland density
2. Abundant subcutaneous fat with increased fibrous stroma
3. Fatty infiltration of the digital nerve with endoneural and perineural fibrosis and enlarged digital artery
4. Bone – wide medullary canal, irregular trabeculae and thickening of periosteum

 

Management

Aim – functional and aesthetic improvement

Counseling –

Inability to establish normal digit

Need for multiple surgeries

 

Surgical procedure aimed at –

1. Limiting ongoing growth
2. Reduce size of digit
3. Correct deviation
4. Amputation

 

Limiting digital growth –

Most reliable method is – Epiphysiodesis

(Other options includes – digital nerve stripping, digital nerve resection, digital artery ligation, compression bandage)

 

Epiphysiodesis –

Can be achieved by –

• Burring or drilling
• Resection of epiphyseal plate
• Physeal stapling in larger bones

Timing of epiphysiodesis –

It is done when the digit reaches the length of the corresponding digit in parent of same gender.

Digital deviation may be corrected in the same setting by a closed wedge resection.

(Hemiepiphysiodesis is another way to manage progressive deviation, but it is not as reliable as corrective osteotomy)

Percutaneous K-wire is required for post-op stabilization following physeal resection, more so if corrective osteotomy was also done.

Complications –

Joint stiffness

Excessive bone formation at the site of physis

Secondary angulation, in case of incomplete phseal destruction

Physeal arrest do not reduces – soft tissue growth and transverse (appositional) growth of the bone.

 

Reducing the digits/ soft tissue debulking –

Usually one side of the digits is debulked at a time (with 3 month interval)

Approach through – midlateral incision or Brunner’s incision

Skin flaps are elevated –> neurovascular bundle is isolated –> excess fat and skin is resected.

 

Skeletal reduction –

Can be achieved by either –

• Narrowing or
• Shortening

Narrowing –

Burring the side of bone or

Performing longitudinal osteotomy. (longitudinal osteotomy is limited by the attachment of flexor sheath)

 

Shortening –

1. Terminalization
2. Excision of middle phalanx
3. Corrective osteotomy (in case of deviated digit – trapezoid osteotmy rather than wedge osteotomy)

 

Terminalization 

It is the simplest procedure.

Many procedures aims at preserving nail while shortening the digit.

1. Barksy procedure – nail on palmar pedicle

Modified by Flatt – to include distal part of distal phalanx and shortened middle phalanx

2. Tsuge procedure –

Nail on dorsal pedicle including dorsal cortex of distal phalnx (although dorsal pedicle is unreliable)

3. Nail island flap – by Rosennberg

Nail raised as islanded flap based on digital neurovascular pedicle – achieved greater transposition proximally and hence greater shortening can be achieved

4. Segmental osteotomies along the length of digit
5. Excision/arthrodesis of MCP joint
6. DIPJ arthrodesis
7. Fujita described radial and ulnar neurovascular pedicle and excising each other to match other
8. Thumb reduction –
   1. MCPJ arthrodesis
   2. Millesi procedure

 

Amputation –

It is the ultimate reduction procedure

Option for single digit or showing progressive uncontrollable growth

Ray amputation/transmetacarpal amputation with digit transposition

Digit transfer from foot or pollicization to create thumb

Amputation is a difficult decision to make for parents, but can save multiple stage surgery to save a deformed digit with limited function

 

Summary of treatment of macrodactyly –

Limitation of growth –

1. Digital nerve stripping
2. Epiphysiodesis

Digit reduction –

Soft tissue reduction – debulking

Skeletal reduction – terminalization

Methods of terminalization –

Repositioning of the nail unit on a shortened skeleton

• • • Palmar pedicle (Barsky procedure)
    • Dorsal pedicle (Tsuge procedure)
    • Nail island flap

Resection of the distal portion of the nail and pulp (Tsuge, Hoshi, Fujita, Bartelli)

Correction of deviation – Closing wedge osteotomy (combined with epiphysiodesis as required)

Thumb macrodactyly –

Metacarpophalangeal arthrodesis

Millesi procedure

Amputation – Ray amputation (with transposition of the digit for central ray amputation)