- Discussion:
- heterogeneous group of intrinsic
dysplasias characterized by x-ray changes in the metaphyses
of the short and long tubular bones (epiphyses remains normal);
- defect appears to lie in proliferative &
hypertrophic zones of physis;
-
hypercalcemia is common;
-
diff dx:
- many pts will initially thought to have a
hypophosphatemic vit D-resistant rickets,
which can lead to the innappropriate administration of Vit D;
-
associated disorders:
- metaphyseal chondrodysplasia may be associated w/ neutropenia, lymphopenia, immune deficiency,
pancreatic exocrine insufficiency, hirschsprung's disease, and intestinal malabsorption;
- Clinical Presentation:
- condition is first recognized in early childhood when children present with
a waddling gait, exaggerated lumbar lordosis,
genu varum, and short stature;
- additional features include:
- mental retardation;
- joint contractures;
- exophthalmic eyes;
- Histology:
- defect appears to lie in proliferative &
hypertrophic zones of physis;
- light microscopy reveals cell clusters or nests rather than normal columnization;
- zone of provisional calcification narrows with irregular vascular invasion, resulting in islands
of unmineralized cartilage extending into the metaphysis;
- Radiographs:
- radiographic appearance of an enlarged metaphysis & widened cupped physis is similar to
rickets;
-
coxa vara occurs without an associated bowed femur;
- it is treated w/ valgus intertrochanteric osteotomy when progressive;
- genu varum may be severe in the Schmid type.
- Schmid type:
- this disorder may arise from defective type X collagen, which is typically found in the hypertrophic zone of the physis;
- patients show mild short sature, leg pains, bowed legs, increased lordosis, and waddling gait;
-
upper extremity:
- mild wrist swelling;
-
flexion contractures of the elbows;
-
lower extremities
- more significantly involved than upper extremities;
- varus deformities of the knees and ankles are prestent, with bowing visible in both the thigh and the leg;
-
genu varum may be severe in the Schmid type;
- surgical correction should be delayed until it is determined that spontaneous correction will not occur.
- Metaphyseal Dysplasia (Pyle's Disease)
- autosomal recessive disorder which manifests at a variable age;
- mild clinical symptoms and signs, including joint pain muscular weakness;
- scoliosis, genu valgum deformity, dental / malocclusion and bone fragility;
- marked expansion of the metaphyseal segments of tubular leads to an "Erlenmeyer flask" appearance,
esp in the distal femur and proximal tibia and fibula;
A constitutively active mutant PTH-PTHrP receptor in Jansen type metaphyseal chondrodysplasia.
E Schipani et al.
Science. Vol 268. 1995. p 98-100.
