Macrodactyly & Pediatric Trigger Digits

Pediatric Hand and Upper Extremity Conditions
Topics: Macrodactyly and Pediatric Trigger Digits

Macrodactyly

Essential Information
Macrodactyly is a rare condition of overgrowth in the hand.  Klein described the first case of macrodactyly in 1824.i

Etiology
  • In true macrodactyly, the enlarged portion of the hand is in the distribution of a major peripheral nerve, most commonly the median nerve. 
    • Nerves in the areas of enlargement were often abnormally bulky, tortuous and infiltrated by a high concentration of fat.
    • Histologically, the hypertrophied tissues appear like benign neurofibromas.
  • Most current explanations on the pathophysiology of macrodactyly involve the derangement of the peripheral nerves, particularly their sensory branches.
  • Other evidence exists for an aberrant localized growth hormone receptor.
Genetics
  • No genetic/hereditary predisposition
 
Incidence
  • Incidence estimated to be around 0.2 per 10 000 births.ii
  • It is three times more common for multiple digits to be involved than a solitary digit with a predilection for the radial side of the hand.
Clinical Evaluation:
History / Exam Findings
  • Tsuyuguchi et al., proposed several criteria for the clinical diagnosis of macrodactyly.
    • One, the condition must be present at birth or by 3 years of age
    • Secondly, the enlarged digit is both longer and wider than normal. 
  • Macrodactyly can affect both the phalanges and the metacarpals.
  • Temtamy and McKusick reserved the term true macrodactyly for only those conditions which also involve the bone.iii
  • Differential Diagnosis:
    • Fibrous dysplasia, lymphedema, arteriovenous malformations, enchondromatosis, and Proteus syndrome and other hamartomatous conditions. 
Imaging / Lab Studies
  • Comparison radiographs should be obtained regularly to document growth.
Classification Schemes
  • Upton classified the four subtypes of macrodactyly, each having its own characteristic histologic appearance.iv
    • Type I: Macrodactyly with nerve-oriented lipofibromatosis
    • Type II: Macrodactyly with neurofibromatosis (von Recklinghausen disease)
    • Type II: Macrodactyly with neurofibromatosis (von Recklinghausen disease)
    • Type III: Macrodactyly with hyperostosis
    • Type IV: Macrodactyly with hemihypertrophy
Treatment:
  • Treatment of macrodactyly is among the most challenging of all congenital hand anomalies and often necessitates fairly aggressive correction. 
    • A clinical case series by Tsuge et al., has even suggested that resection of an involved nerve in some cases can alter progressive growth of the affected digit.v
    • Physeal arrest should be performed when the digit reaches adult length.
  • Surgical treatment includes:
    • Soft tissue debulking
    • Nerve resection/stripping
    • Corrective and narrowing osteotomies
    • Arthrodesis
  • Additionally, the place of amputation for macrodactyly should not be overlooked and is an acceptable part of the treatment algorithm.
  • The goals of operative treatment of macrodactyly are to:
    • Control growth and reduce size
    • Maintain motion
    • Preserve protective sensation.
Outcomes:
  • Prognosis
    • The natural history of the condition is progressive growth until physeal closure.
    • Joints become progressively stiff as the enlarged tissues prevent flexion.
    • Carpal tunnel syndrome can develop as the enlarged nerve becomes compressed at the carpal tunnel.
    • In severely enlarged digits vascular insufficiency can occur.
  • Potential Complications
    • Complications are common
    • Despite surgery the digit can still continue to enlarge. 
    • Debulking procedures often result in loss of motion, nail bed deformities, and scarring. 
  • Other less common complications include loss of sensation and skin flap necrosis.


Pediatric Trigger Digits

Essential Information
Pediatric trigger thumb is a stenosing tenovaginitis of the flexor pollicis longus tendon. 
 
Etiology

  • The primary pathological process is a mismatch in size between the flexor tendon and the A1 pulley which causes obstruction to tendon gliding.
  • Although there is still some controversy, most authors now agree that the condition is developmental in nature. 
    • Numerous large prospective screening studies of neonates have demonstrated its absence at time of birth.vi
  • Histopathologic studies have demonstrated no degenerative or inflammatory changes.vii
Genetics
  • No known genetic etiology involved
Incidence
  • By one year of age, however, approximately 1 in 2,000 children will have trigger thumbs. 
  • One-third of patients will go on to demonstrate bilateral thumb involvement.
  • Patients typically present during the first 3 years of life.
Risk Factors
  • Increased in Trisomy 13
Clinical Evaluation:
History / Exam Findings
  • On the exam, patients typically present with either triggering or a fixed flexion contracture of the IP joint.
    • Can be associated with the formation of a secondary nodule, called “Notta’s node”,
    • Fibrosis develops within the flexor tendon from chronic friction against the A1 pulley.
  • Pain is very uncommon
Imaging / Lab Studies
  • No imaging studies are typically required
 
Treatment:
  •  Current treatment guidelines recommend observation for 6 to 12 months in the newly presenting trigger thumb.
    • Limited information exists regarding the role of splinting or formal therapy and stretching on the natural history of the symptomatic pediatric trigger thumb. 
  • Corticosteroid injections should NOT be used in the pediatric patient with trigger thumb
  • Surgical release is typically recommended for fixed flexion contractures or symptomatic and functionally limiting triggering in patients >18 months of age.
    • Dinham and Meggitt published a retrospective case series of 131 thumbs in 105 patients.viii
      • < 6 months = 30% spontaneous resolution
      • > 6 months = 12%
      • Baek et al. reported on the natural history of trigger thumb and found that in 71 thumbs in 53 patients, 63% achieved full IP joint extension at a mean age of 5 years.ix
Outcomes:
  • Prognosis
    • If not surgically treated it is postulated that resolution of pediatric trigger thumb occurs because as the child grows the Notta nodule gradually dilates the A1 pully, thereby reducing any constriction.
    • Surgery should be performed before the age of 4 years to prevent the rare residual deformity that may occur. 
  • Potential Complications
    • There have been sporadic reports of radial deviation and rotational deformity of the IP joint if the condition is left untreated.x

 

__________________________________________________


Macrodactyly
[i]  Wood VE: Macrodactyly, J Iowa Med Soc 59:922, 1969.
 
[ii] Lamb DW, Wynne-Davies R. Incidence and genetics. In: Buck-Gramcko D, ed. Congenital malformations of the hand and forearm. London: Churchill Livingstone; 1998:21–27. 
 
[iii] Temtamy S, McKusick V: The genetics of hand malformations, Birth Defects Orig Artic Ser 14:i, 1978.
 
[iv] Upton J: Congenital anomalies of the hand and forearm. In McCarthy JG, editor: Plastic surgery, vol 8, Philadelphia, 1990, Saunders, p 5279.
 
[v] Tsuge K, Ikuta Y: Macrodactyly and fibro-fatty proliferation of the median nerve, Hiroshima J Med Sci 22:83, 1973.

 

__________________________________________________

Pediatric Trigger Finger
[vi] Rodgers WB, Waters PM. Incidence of trigger digits in newborns. J Hand Surg Am. 1994;19:364–368. 
 
[vii] M.Waters P, Bae DS. Pediatric Hand and Upper Limb Surgery : A Practical Guide. Philadelphia, US: Wolters Kluwer Health; 2015.
 
[viii] Dinham JM, Meggitt BF. Trigger thumbs in children. A review of the natural history and indications for treatment in 105 patients. J Bone Joint Surg Br. 1974 Feb;56(1):153-5.
 
[ix] Baek GH, Kim JH, Chung MS, Kang SB, Lee YH, Gong HS. The natural history of pediatric trigger thumb.  J Bone Joint Surg Am. 2008 May;90(5):980-5.
 
[x] Herdem M, Bayram H, Togrul E, et al. Clinical analysis of the trigger thumb of childhood. Turk J Pediatr. 2003;45:237–239. 
 


 

Comments
Blog post currently doesn't have any comments.