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Defective mineralization: osteoid in adults (osteomalacia) vs physis in children (rickets). Etiologies: Vit D deficiency/resistance, phosphate deficiency (tumor‑induced, hereditary), renal tubular acidosis, CKD. Clinical: bone pain, proximal myopathy, waddling gait; in children—wrist/ankle widening, bowing, rachitic rosary, Harrison sulcus. Biochemical: Low Ca/PO4, High ALP, High PTH, Low 25‑OH Vit D (pattern varies in renal disease). Radiology: Looser’s zones; in rickets—widened physes with cupping/fraying, osteopenia. Treatment: Vitamin D and calcium; treat specific causes (phosphate, calcitriol, burosumab in XLH).
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Osteomalacia and rickets are metabolic bone disorders characterized by defective mineralization of osteoid. The underlying problem is inadequate deposition of calcium and phosphate into the bone matrix, resulting in soft and structurally weak bones.
The condition is termed rickets when it occurs in children with open growth plates, and osteomalacia when it occurs in adults after epiphyseal closure. Although both conditions share similar biochemical abnormalities, the skeletal manifestations differ because rickets affects the growing skeleton whereas osteomalacia affects mature bone.
Normal bone mineralization requires adequate calcium and phosphate levels along with appropriate vitamin D activity. Vitamin D promotes intestinal absorption of calcium and phosphate and supports mineral deposition in osteoid.
When vitamin D deficiency or phosphate deficiency occurs, osteoid formation continues but mineralization fails. As a result, the bone matrix remains soft and mechanically weak. This leads to skeletal deformities in children and bone pain with fractures in adults.
Multiple causes may lead to osteomalacia and rickets. The most common cause worldwide is vitamin D deficiency.
| Category | Examples |
|---|---|
| Vitamin D deficiency | Poor nutrition, lack of sunlight |
| Malabsorption | Celiac disease, inflammatory bowel disease |
| Renal disease | Renal osteodystrophy |
| Genetic disorders | Vitamin D–dependent rickets |
| Phosphate deficiency | X-linked hypophosphatemic rickets |
Clinical manifestations depend on the age of the patient and severity of mineralization defect.
Radiographic findings differ between rickets and osteomalacia because rickets involves abnormalities of the growth plate.
| Finding | Description |
|---|---|
| Metaphyseal cupping | Concave deformity of metaphysis |
| Metaphyseal fraying | Irregular metaphyseal margin |
| Widened growth plate | Due to impaired mineralization |
| Looser zones | Pseudofractures seen in osteomalacia |
Laboratory investigations help confirm the diagnosis and determine the underlying cause.
| Test | Typical Finding |
|---|---|
| Serum calcium | Low or normal |
| Serum phosphate | Low |
| Alkaline phosphatase | Elevated |
| Vitamin D levels | Low |
Treatment focuses on correcting the underlying metabolic abnormality and preventing skeletal deformities.
Orthopaedic treatment may be required for severe deformities. Surgical correction using osteotomy may be indicated in advanced cases with persistent deformity.
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