Amstutz developed a classification scheme for patients with congenital proximal femoral focal deficiency (PFFD). This can help predict the clinical course and determine the optimum type and timing for intervention.
Parameters:
(1) appearance of the femur
(2) ossification in the femur and capital femoral epiphysis
(3) acetabulum and pelvis
(4) deformity
NOTE: Since the scheme defines deficiencies in the proximal femur, some part of the femur is present, which distinguishes it from congenital absence of the femur.
Parameter |
Type I |
Type II |
Type III |
appearance of the femur |
short with considerable bowing; sclerosis of the medial femoral cortex; often a laterally positioned beak |
subtrochanteric pseudoarthrosis with persisting defect |
early X-rays show proximal bulbous ossification to femoral shaft |
ossification of proximal femur and capital femoral epiphysis |
ossification of the capital femoral epiphysis may be delayed; lesser trochanter may fail to ossify |
delayed and irregular; ossification of capital femoral epiphysis shows marked delay |
ossification of capital femoral epiphysis markedly delayed; see subtypes below |
acetabulum and pelvis |
present; femoral head is well centered |
present |
present |
deformity |
stable with nonprogressive coxa varus |
progressive varus |
varus may or may not progress |
Subtypes for Type I:
(1) Type 1B: progressive hip dysplasia with early onset arthritis
(2) Type 1A: absence of progressive hip dysplasia
Subtypes of Type III:
(1) Type 3A: complete ossification without varus deformity
(2) Type 3B: delayed ossification with varus progression
(3) Type 3C: spotty ossification with wide neck defect
(4) Type 3D: absent ossification with wide cervical pseudoarthrosis
|
Type IV |
Type V |
femur |
early X-rays show proximal end of femoral shaft tapers sharply to a point; capital femoral epiphysis present but appears separate; persisting pseudoarthrosis |
distal parts only |
ossification of proximal femur and capital femoral epiphysis |
delayed ossification of the capital femoral epiphysis |
delayed ossification of bony parts present; capital femoral epiphysis absent |
acetabulum and pelvis |
present but dysplastic |
acetabulum absent; pelvis abnormal |
deformity |
contractures with proximal migration of distal elements |
unstable hip; positive Trendelenberg; severe stunting |
where:
• "capital" refers to the head of the femur
• The hallmarks of the Type V include an iliac projection just above the usual acetabular anatomical site and a spherical obturator foramen. If bilateral the pelvis is square or box-like.
Specialty: Surgery, orthopedic, Genetics, Pedatrics
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