Disproportionately large digit noted at birth or that develops within 1st 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 –
- Macrodactyly with plexiform form of NF and is often bilateral
- There may be osteochondral mass a/w skeletal enlargement
Type 3 –
- Osteocondral periarticular masses developing in infancy.
- No significant nerve involvement.
- Digits are nodular and stiff and other skeletal anomalies can be seen.
- Rare type
Type 4 –
- Rare
- All digit involved but less severe than type 1 & 2
- Intrinsic muscle hypertrophy or abnormal intrinsic anatomy
- 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
- Advanced bone age
- Abnormal digits and deviation
- 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 –
- Ollier disease
- Maffuci syndrome
- KTW syndrome
- 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 –
- Increased subcutaneous fat
- Enlarged tortuous digital nerve
- Skeletal overgrowth in all direction
- Palmar aspect is more affected than dorsal
- Distal finger is more affected than proximal
- Flexor sheath may be thickened
- Tendons are normal
Histology –
- Thickening of skin with decreased sweat gland density
- Abundant subcutaneous fat with increased fibrous stroma
- Fatty infiltration of the digital nerve with endoneural and perineural fibrosis and enlarged digital artery
- 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 –
- Limiting ongoing growth
- Reduce size of digit
- Correct deviation
- 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 –
- Terminalization
- Excision of middle phalanx
- 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.
- Barksy procedure – nail on palmar pedicle
Modified by Flatt – to include distal part of distal phalanx and shortened middle phalanx
- Tsuge procedure –
Nail on dorsal pedicle including dorsal cortex of distal phalnx (although dorsal pedicle is unreliable)
- 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
- Segmental osteotomies along the length of digit
- Excision/arthrodesis of MCP joint
- DIPJ arthrodesis
- Fujita described radial and ulnar neurovascular pedicle and excising each other to match other
- Thumb reduction –
- MCPJ arthrodesis
- 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 –
- Digital nerve stripping
- 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)
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