**Question:** Which of the following is not a sign of active rickets?

A. Delayed bone age maturation
B. Increased bone density
C. Increased bone deformities
D. Reduced bone deformities

**Core Concept:** Rickets is a skeletal disorder in children caused by vitamin D deficiency or impaired calcium absorption, leading to impaired bone mineralization. Active rickets refers to the stage when bone deformities are present.

**Why the Correct Answer is Right:** Reduced bone deformities indicates a less severe stage of rickets, such as the recovery phase after treatment has started. It is not a characteristic sign of active rickets.

**Why Each Wrong Option is Incorrect:**

A. Delayed bone age maturation (Herthel-Davis sign): This sign is present in rickets due to impaired growth plate development, indicating that the bone age is older than the chronological age. Delayed bone age maturation is a characteristic sign of active rickets, making option A incorrect.

B. Increased bone density (osteopenia): Rickets leads to decreased bone mineralization, resulting in osteopenia. This sign is not specific to active rickets and could be present in other conditions.

C. Increased bone deformities: This sign is a characteristic feature of active rickets, with ongoing abnormal bone mineralization leading to deformities.

D. Reduced bone deformities: As mentioned earlier, reduced bone deformities indicate a less severe stage of rickets and is not a sign of active rickets.

**Clinical Pearl:** Active rickets should prompt a thorough evaluation for its underlying cause such as vitamin D deficiency or hypophosphatemic rickets. Treatment typically includes vitamin D supplementation and phosphorus correction to prevent further bone deformities and improve bone mineralization.