Congenital Limb Deficiencies

Question 1

Classification

Answer 1

Swanson and colleagues classification:

1. failure of formation of parts (arrest of development)
2. failure of differentiation (separation of parts)
3. duplication
4. overgrowth
5. undergrowth (hypoplasia)
6. congenital constriction band syndrome
7. generalized skeletal deformities.

ISO/ISPO Classification: provides common language

• Transverse- limb has developed normally to a particular level beyond which no skeletal elements exist, although digital buds are present. Described by naming the segment in which the limb terminates and the describing the level within the segment beyond which no skeletal elements exist
• Longitudinal- reduction or absence of an element or elements occurs within the long axis of a limb. Normal skeletal elements may be present distal to the affected bones. Described by naming the bones affected in a proximal to distal sequence and stating whether each affected bone is totally or partially absent.

Question 2

Origin

Answer 2

limb buds appear at the end of the 4th week of embryonic development–arises from mesenchymal tissue

Next 3 weeks limb buds grow and differentiate into identifiable limb segments

Development of limb buds occurs in proximodistal sequence. UE development occurs before LE development

Mesenchymal tissue undergoes chondrification to become cartilage models of individual bones

End of 7th week = embryonic skeleton is present

Question 3

Causes of Congenital Limb Deficiencies

Answer 3

genetic, vascular, teratogenic, amniotic bands

For many children the exact cause is unknown–32% of cases the cause is unknown

Genetic link may be associated with few limb anomalies—most result from a sporadic genetic mutation

Many limb deficiencies may be associated with other congenital anomalies (VATER, holt-oram, fanconi, poland, thrombocytopenia- absent radius)
–theory that disruption of the blood supply in the subclavian artery during early embryonic development may be cause of congenital limb deficiencies

Teratogenic- thalidomide, contraceptives, irradiation

• account for only 4% of cases
• low maternal intake of riboflavin associated with transverse limb deficiencies
• must be present between week 3 and 7 of embryonic development to produce a limb deficiency

Question 4

Levels of limb deficiency

Answer 4

2-7 per 10,000 live births

upper limb 58% of cases, longitudinal deficiency of hand is most common presentation

20% affect more than 1 limb

Most transverse are unilateral- transverse below the elbow most common
- rudimentary finger vestiges–> nubbins

Proximal femoral focal deficiency (PFFD)

• complex le congenital limb deficiency
• absence or hypoplasia of the proximal femur with varying degrees of involvement of the acetabulum , femoral head, patella, tibia, and fibula
• can be unilateral or bilateral
• If unilateral, the contralateral limb may exhibit subtle deficiencies, such as hypoplasia of the femur that may not be recognized initially
• Clinical manifestations of PFFD: shortened thigh held in flexion, abduction, and ER. Hip/knee flexion contracture, severe LLD, with foot often at the level of the opposite knee
• may also have instability of the knee joint secondary to absent or deficient cruciate ligaments and 70-80% incidence of total longitudinal deficiency of the fibula
• 15% have bilateral involvement
• 1 in 50,000 births, usually of unknown origin

Question 5

Aitken Classification for PFFD

Answer 5

A- femoral head present, acetabulum normal, short femoral segment, bony connection between components of femur, femoral head in acetabulum, subtrochanteric varus angulation- often with pseudoarthrosis

B- femoral head present, acetabulum is adequate or moderately dysplastic, femoral segment short usually proximal bony tuft, no osseous connection between shaft and head, femoral head in acetabulum

C- femoral head absent or represented by ossicle, acetabulum is severely dysplastic, femoral segment short usually proximally tapered, may be osseous connect between shaft and proximal ossicle, no articular relationship btwn femur and acetabulum

D- absent femoral head, acetabulum absent, obturator foramen enlarged, pelvis squared in bilateral cases, short and deformed femoral segment, no relationship btwn femur and acetabulum