Splaying and cupping of the metaphysis is seen in –
**Core Concept**
Splaying and cupping of the metaphysis refer to the widening and concavity of the metaphyseal region adjacent to the growth plate in long bones. This phenomenon is a characteristic feature of rickets, a disease caused by vitamin D deficiency.
**Why the Correct Answer is Right**
In rickets, the defective mineralization of the bone matrix leads to an imbalance between bone resorption and bone formation. As a result, the metaphyseal region becomes widened and concave due to the accumulation of unmineralized osteoid tissue. This process is mediated by the reduced activity of alkaline phosphatase, an enzyme essential for bone mineralization. The growth plate's cartilaginous matrix also undergoes changes, leading to an abnormal growth pattern.
**Why Each Wrong Option is Incorrect**
* **Option A:** Rickets is not primarily associated with increased bone resorption, which is more characteristic of osteoporosis.
* **Option B:** Splaying and cupping of the metaphysis are not typical features of osteomalacia, a condition that affects adults and is also caused by vitamin D deficiency, but it primarily affects the diaphysis and cortical bone.
* **Option C:** Caffey's disease, also known as infantile cortical hyperostosis, presents with inflammation of the periosteum and is not associated with metaphyseal changes.
**Clinical Pearl / High-Yield Fact**
Rickets is a classic example of a disease that affects bone growth and development, highlighting the importance of adequate calcium and vitamin D levels in children.
**Correct Answer: A. Rickets.**