Congenital Abnormalities ✅ Flashcards
What are the categories of congenital limb defects?
- Reduction defects
- Duplication defects
- Dysplasia (malformation)
What are the types of reduction defects?
- Entire limb (amelia)
- Part of limb (meromelia)
What happens in duplication defects?
There are extra limb elements
What is the most common duplication defects?
Extra digits (polydactyly)
Give 2 examples of limb dysplasia?
- Fusion of digits (syndactyly)
- Excessive growth of parts of the limb (gigantism)
What processes can limb defects be broadly attributed to?
- Developmental arrest (failure to form)
- Failure of differentiation
- Duplication
- Overgrowth (hyperplasia)
- Undergrowth (hypoplasia)
- Focal defects
- General skeletal abnormalities
Give an example of a focal defect causing limb defects
Amniotic fluid band syndrome
Give an example of a general skeletal abnormality causing limb defects
Osteogenesis imperfecta
What is true of most limb defects?
They have multifactorial aetiologies with a combination of genetic and environmental factors (but either may predominate)
Give an example of a limb malformation where genetic causes predominante?
Polydactyly or ectrodactyly (absence of fingers or toes)
How does postaxial hand polydactyly differ between black and white children?
In black children it is commonly an isolated disorder, and is autosomal dominant.
In white children it is usually syndromic, and is autosomal recessive
What causes DDH?
Not clear, but usually multifactorial
What are the risk factors for DDH?
- Female gender
- Family history
- Oligohydramnios
- Breech position
- Presence of other congenital abnormalities, e.g. neuromuscular disorders
Describe the hip joint in normal development
The head of the femur is smooth and rounded, and the acetabulum is cup-shaped
Describe the hip joint in DDH
There may be abnormalities of the shape of the head of the femur, acetabulum, or surrounding structures, meaning the acetabulum and femur may not be in close contact
What might happen to the hip in DDH?
Depending on degree of abnormality, may be subluxed or dislocated
What is talipes equinovarus?
A complex abnormality where;
- The entire foot is inverted and supinated
- The forefoot adducted
- The heel is rotated inwards and in plantar flexion
- The affected foot is shorter, and the calf muscles thinner than normal
Can the position of the foot be corrected with passive manipulation in talipes equinovarus?
No, it is fixed and cannot be corrected completely
Is talipes equinovarus unilateral or bilateral?
Often bilateral
What gender is talipes equinovarus more common in?
Males (2:1)
Its talipes equinovarus familial?
Can be, but usually idiopathic
What might talipes equinovarus be secondary to?
- Oligohydraminos
- Malformation syndrome
- Neuromuscular disorder such as spina bifida
What is used to treat talipes equinovarus?
The Ponseti method
What is the Ponstei method?
Manipulative technique involving serial casting
What is the advantage of the Ponseti method?
It usually avoids the need for invasive surgery
What does talipes equinovarus need to be differentiated from?
- Positional talipes
- Vertical talus
How is talipes equinovarus differentiated from positional talipes?
In positional talipes:
- The foot is of normal size
- Deformity is mild and can be corrected with passive manipulation
What are the features of vertical talus?
Foot is stiff and rocker-bottom in shape
What is talipes equinovarus often associated with?
Other malformations
What are the environmental causes of limb defects?
- Drug teratogens
- Amniotic tissue/constricted uterus
At what time are developing foetuses particularly vulnerable to drugs causing limb defects?
4-8 weeks gestation
What drug teratogens may lead to limb defects?
- Thalidomide
- Any drug which influences general cell metabolism or cell proliferation
- Warfarin
- Phenytoin
- Valproic acid
- Acetazolamide
How does thalidomide cause limb defects?
It disrupts cell adhesion receptors and inhibits angiogenesis
What limb defects are associated with thalidomide exposure?
- Amelia and phocomelia
- Minor deformities, e.g. thumb hypoplasia, syndactyly between index finger and thumb
Give an example of a drug that influences cell metabolism/proliferation
Triethylene melamine (chemotherapy alkylating agent)
What does limb growth in uterus require?
Physical space
When might space in utero be restricted leading to limb deformities?
- Constricted uterine environment, e.g. bicornuate uterus
- Intrauterine compression, e.g. multiple pregnancy
What is an amniotic band?
When fibrous amniotic tissue detatches and wraps around the developing limb
What can the consequence of an amniotic band be?
It can prevent growth or development of a limb or part of a limb
What is the prevalence of amniotic band syndrome?
Affects up to 1 in 1200 live births
What is amniotic band syndrome associated with?
Increased risk of other abnormalities, e.g. cleft lip and palate, talipes equinovarus
What might cause congenital structural defects of the spine?
Failure of vertebrae formation, separation, or fusion
What are the types of spinal abnormality?
- Scoliosis
- Kyphosis
- Lordosis
What is scoliosis?
Where the spine develops to the left or right
What is kyphosis?
When the spine has a convex overcurvature
What is lordosis?
When the spine sways backwards
What does the involvement of the vertebra growth plate influence?
The growth potential
Differences in progression and deformity
What is the most common developmental spine condition?
Congenital scoliosis
What causes congenital scoliosis?
The aetiology is not fully known, but failure of sclerotome segmentation results in vertebrae that are abnormally connected on one side, causing asymmetrical growth rates.
There may also be disruption of the normal shape of the vertebra, causing a wedge shape, which can cause asymmetrical growth.
Is congenital scoliosis the same thing as idiopathic scoliosis?
No
What are the categories of presentation of idiopathic scoliosis?
- Early onset (under 5 years)
- Late onset
What is the most common presentation of idiopathic scoliosis?
Late-onset, mainly in girls 10-14 years of age during their pubertal growth spurt
Is secondary scoliosis common?
Yes
What can cause secondary scoliosis?
- Disorders that result in neuromuscular imbalance
- Disorders of bone or cartilage
- Leg length discrepancy
Give 3 examples of disorders that result in neuromuscular imbalance
- Cerebral palsy
- Muscular dystrophy
- Polio
Give 2 examples of disorders of bone or cartilage that may lead to scoliosis?
- Neurofibromatosis
- Marfan’s syndrome
What should be done if a child has a congenital vertebral abnormality?
Other systems should be investigated to exclude syndrome characteristics, e.g. VACTERL association
What is arthrogyposis?
The collective term for a number of conditions associated with joint contractures at birth
What can result in joint contractures at birth?
Factors that inhibit normal joint development or movement (intrinsic or extrinsic)
Give 2 examples of extrinsic factors that may cause joint contractures?
- Oligohydraminos
- Viral infections
What intrinsic factors might cause joint contractures?
Underlying genetic/molecular abnormalities leading to connective tissue, muscle, or neurological abnormalities
What categories can arthrogryposis be divided into?
- Amyoplasia
- Distal
- Syndromic
What is amyoplasia?
Muscle weakness and multiple severe joint contractures
What is distal arthrogryposis?
Contractures affecting hands and feet
What is syndromic arthrogryposis?
Associated with congenital neurological or muscle disease
