Congenital Anomalies Flashcards
At what age of development does the limb bud appear? When are digital rays evident?
Streeter divided human embryonic development into 23 stages. Limb development and differentiation are rapid
processes that occur between the third and eighth postovulatory weeks. The limb bud, called Wolff’s crest, is well
defined at day 30. It is a ventral swelling mesoderm covered by a thick layer of ectoderm, called the apical ectodermal
ridge (AER). By day 41 digital rays are present, and by day 48 joint interzones are evident histologically. Usually by the
time the expectant mother is sure that she is pregnant, most of the upper limb differentiation has been completed.
What does syndactyly mean? Is it the most common congenital anomaly?
Syndactyly (Greek: syn = together, dactyly = finger) is commonly used to describe webbed digits and is the second most
common congenital anomaly. The most common are duplications, particularly preaxial or thumb duplications in the Asian
population and postaxial or ulnar duplications in African-American and Native-American populations. The incidence of
duplications varies according to the population but overall occurs in 3.8:1000 to 12:1000 live births.
Syndactyly (Greek: syn = together, dactyly = finger) is commonly used to describe webbed digits and is the second most
common congenital anomaly. The most common are duplications, particularly preaxial or thumb duplications in the Asian
population and postaxial or ulnar duplications in African-American and Native-American populations. The incidence of
duplications varies according to the population but overall occurs in 3.8:1000 to 12:1000 live births.
Syndactyly (Greek: syn = together, dactyly = finger) is commonly used to describe webbed digits and is the second most
common congenital anomaly. The most common are duplications, particularly preaxial or thumb duplications in the Asian
population and postaxial or ulnar duplications in African-American and Native-American populations. The incidence of
duplications varies according to the population but overall occurs in 3.8:1000 to 12:1000 live births.
What are the principles of syndactyly correction?
** Use of full-thickness flaps for commissure reconstruction
** Zigzag incisions on the palmar surface
** Use of full-thickness skin grafts
** Equal division of flaps between each partner digit
** Meticulous, atraumatic technique
** Adequate postoperative immobilization
** Staged release of the radial and ulnar sides of a digit; release of both sides during one procedure may compromise
the vascular supply to the digit
When operating on young children, it is important to work under general anesthesia and to use a pneumatic tourniquet
and absorbable 6-0 or 5-0 chromic suture material.
What are the most common problems after syndactyly correction?
Infection, graft or flap maceration, and graft loss are almost always related to the child’s activity and/or inadequate
immobilization. Surgeons with children of their own do not hesitate to protect operated limbs in a long arm cast
extending well proximal to the elbow flexed at 90°. Single residents without children do not always appreciate the
problems that most parents encounter with controlling active young children. Early problems also may occur after
children wet their casts or dressings in bathtubs or swimming pools.
Long-term problems include recurrence of the webbing or “web creep,” which is related to scar contracture at the
base of the commissure or along the incision lines. Zigzag incisions are intended to reduce this potential contracture.
Skin grafts often are hyperpigmented and, if harvested within the hair-bearing escutcheon, may become hirsute during
adolescence. Inadequate correction of the first
What is the most important web space in the hand?
The thumb–index or first web space is unquestionably the most important. Of all techniques described for correction of
congenital hand anomalies, release of the first web space is the most significant functionally and aesthetically. In a pure
analysis, a “basic hand” has three components: a mobile digit or thumb on the radial side, a first web space, and a post
or digit on the opposite side of the hand.
What is the best method for surgical release of the first web space?
The surgeon must learn to use one or two methods well. For minimal to moderate contractures, the four-flap Z-plasty
provides the greatest release and maintains the best concavity between the thumb and index metaphalangeal (MP)
joints. A single Z-plasty and the five-flap Z-plasty, also called the “jumping man,” are good alternatives. Many varieties
of dorsal rotational flaps from the thumb or index metacarpal regions have been described with the use of skin grafts.
These techniques are not preferred because they leave a conspicuous skin graft in a visible position of the hand. These
local flaps are indicated in complex problems such as the Apert hand.For severe contractures, soft tissue is often needed. Free tissue transfers in infants or young children often
are cumbersome and technically difficult. Distally based forearm (radial artery or dorsal interosseous artery)
fasciocutaneous flaps have been described for children with arthrogryposis, windblown hands, and hypoplastic thumbs
with tight contractures and are advised for use by experienced surgeons.
What contributes to thumb–index contracture
Tight skin is the most obvious etiology, but tight investing fascias of the first dorsal interosseous and adductor pollicis
muscles almost always are found and must be excised. Often a tight band is present between the two muscles.
Occasionally, a tight thumb carpometacarpal (CMC) joint may be found; it usually is suspected on physical examination.
How is syndactyly clinically classified?
The level of webbing between digits is complete if it extends to the fingertip and incomplete with a more proximal
termination. A simple syndactyly refers to soft tissue connections between adjacent digits, whereas complex refers to
bone or cartilaginous unions. Complicated refers to abnormal duplicated skeletal parts within the interdigital space
(Fig. 118-1). The most common pattern is bilateral simple, incomplete syndactyly of the long and ring fingers. Many
such patients have a simple syndactyly involving toes 2 and 3 on one or both feet.
Do children need more surgery after syndactyly repair?
There is always a chance that contractures will require future correction. The literature cites a secondary operation rate
of approximately 10%. The incidence is much higher in complex and complicated cases and in cases with postoperative
complications. There is a direct relationship between carefully planned and executed surgery and a low complication
rate. Children and adults with central complex polysyndactyly invariably need secondary corrections. This variety is the
most difficult to treat.
Geneticists and pediatricians use the terms malformation, deformation, and
disruption. What do they mean?
The dysmorphology approach to congenital anomalies divides defects into one of three sequences, which are defined as
problems that lead to a cascade of events:
** In a malformation sequence, poor formation of tissue within the fetus initiates the chain of defects, which may
range from minimal to severe. All gradations of radial dysplasia, ranging from absence of the thenar muscles
to complete absence of the radius resulting in the club hand posture, are examples. Occurrence rate is in the
5% range. Radial dysplasias also are associated with malformation in other organ systems, such as the VATER
association (vertebral anomalies, anal atresia, tracheoesophageal fistula, renal anomalies, and radial dysplasia) and
Holt-Oram syndrome (radial dysplasia and congenital heart disease).
** The deformation sequence involves no intrinsic problem with the fetus or embryo; instead, abnormal external
mechanical or structural forces cause secondary distortion or deformation. Tethering or constriction of limb parts
by anular bands in the constriction ring syndrome is a prime example. The occurrence rate is very low.
** In the disruption sequence, the normal fetus or embryo is subjected to tissue breakdown or injury, which may be
vascular, infectious, mechanical, or metabolic in origin. The hand deformities associated with maternal ingestion of
thalidomide or alcohol are good examples.
