This is a very nice article of five common congenital hand conditions. The online journal includes three informative videos of surgeries with tips.
Syndactyly is a common congenital hand anomaly, occurring in approximately one in every 2000 to 3000 live births. Syndactyly can be inherited in an autosomal dominant manner, with variable expression or reduced penetrance. It may also occur sporadically.
Syndactyly is classified as
- complete when the fingers are fused all the way to the tip, including the nail folds
- incomplete when the nail folds are not involved
- simple when the fingers are fused by a skin bridge
- complex when the bones are fused together
Syndactyly between the middle and ring fingers is most common, occurring in 57% of the cases, followed by the ring and little fingers, which occurs in 27% of the cases.
Constriction Ring Syndrome
Constriction ring syndrome is a rare condition with a reported incidence ranging from one in 1200 to one in 15,000 births. The index, middle, and ring fingers are frequently affected, whereas the thumb is occasionally involved. Deformities usually occur in multiple extremities and are most predominant in the distal parts.
Constriction ring syndrome is a condition in which the limbs or digits of the fetus become entangled with strands of the embryonic membrane. This entanglement can create problems which include amputation, acrosyndactyly, and lymphedema.
The part of the finger distal to the constriction ring is often hypoplastic or absent, whereas the proximal part is intact.
- Mild constriction ring is often asymptomatic.
- Moderate constriction ring causes lymphedema distal to the ring.
- Severe constriction ring blocks circulation of the arterial and venous system and causes nerve palsy resulting from nerve compression.
The incidence of duplicated thumb (preaxial polydactyly) is approximately one in 3000 live births. It is most commonly found in Asians (2.2 in 1000). The incidence in other groups: Native Americans (0.25 in 1000), African Americans (0.08 in 1000), and Caucasians (0.08 in 1000).
The majority of duplicated thumb cases are sporadic and unilateral, and do not require genetic consultation. It is possible that triphalangeal thumb is associated with an autosomal dominant inheritance pattern.
Wassel Classification--Types I to VII based on level of duplications:
I : bifid distal phalanx (DP)(bone under the finger nail)
II: duplicated DP
III: bifid proximal phalanx (PP) (digit bone nearest the palm)
IV: most common type with duplication of proximal phalanx which rest on broad metacarpal
V: bifid metacarpal (MC) (bone in palm)
VI: duplicated MC
Hypoplastic thumb can be present in isolation or in combination with any radial deficiency. After duplicated thumb, hypoplastic thumb is the second most frequently encountered thumb anomaly. Bilateral thumb involvement occurs in approximately 60% of children with thumb hypoplasia.
The Blauth-Buck-Gramcko classification is widely used to describe the hypoplastic thumb and is based on web space narrowing, hypoplasia of musculoskeletal components, joint instability, and abnormalities of extrinsic tendons.
Hypoplastic thumbs are associated with systemic syndromes such as Holt-Oram syndrome; the vertebral, anal, tracheal, esophageal, phalangeal, and renal (VATER) anomalies; or Fanconi anemia in 18 to 43 percent of the patients. The entire affected upper extremity should be examined to determine the extent of the deficiency over the radial side of the limb.
Trigger thumb in children is characterized by flexion at the interphalangeal joint and rarely presents with snapping as in adults. In most cases, a nodule or thickening of the A1 pulley is palpable.
Controversy remains as to whether the trigger thumb found in children is a congenital disorder or acquired after birth.
A prospective investigation of 1166 neonates showed no trigger thumb at birth, but two cases were observed at a 1-year follow-up. Several other studies have also supported the opinion that childhood trigger thumb is an acquired rather than congenital condition. However, cases of trigger thumb associated with trisomy 13 (Patau syndrome), fraternal twins, and families with generational occurrence indicate that there may be a heritable component in certain patient populations.
This article and the companion videos are worth your time.
Treatment of Common Congenital Hand Conditions; Oda, Takashi; Pushman, Allison G.; Chung, Kevin C.; Plastic & Reconstructive Surgery. 126(3):121e-133e, September 2010.