Question

X-ray of a 5 year old child is shown in the image below. Bone mineral density is normal. Identify the condition.

[X-ray of knee joint showing subperiosteal haemorrhage, scorbutic zone (Trummerfeld zone), dense zone of provisional calcification (White line of Frankel), Ring epiphysis (Wimberger ring), and Pelken's spur]

• A. Rickets
• B. Scurvy
• C. Metaphyseal dysplasia
• D. Osteopetrosis

Hint:

Normal bone mineral density with subperiosteal haemorrhages and Frankel's white line on X-ray points to a vitamin deficiency affecting collagen.

Answer 1

The Correct Option is B

Step 1: Analyse the X-ray findings. The X-ray of the knee in this 5-year-old shows the following classic radiological signs:
- Subperiosteal haemorrhage: due to vitamin C deficiency impairing collagen synthesis
- Scorbutic (Trummerfeld) zone: radiolucent zone at the metaphysis representing the zone of poorly mineralised osteoid
- White line of Frankel: dense zone of provisional calcification at the metaphysis
- Wimberger ring: ring epiphysis with calcified periphery and radiolucent centre
- Pelken's spur: lateral cortical spur at the metaphysis

Step 2: Key differentiating point. The question states bone mineral density is normal. In rickets, there is generalised osteopenia and widened, frayed metaphyses due to accumulation of unmineralised osteoid (defective mineralisation). In scurvy, bone mineral density is preserved because the defect is in collagen synthesis, not mineralisation per se.

Step 3: Pathophysiology of scurvy. Vitamin C (ascorbic acid) is essential for hydroxylation of proline and lysine in collagen synthesis. Deficiency leads to abnormal collagen, causing subperiosteal haemorrhages (from fragile periosteal blood vessels), bleeding gums, and perifollicular haemorrhages. The unique X-ray signs (Frankel's line, Pelken's spur, Wimberger ring, Trummerfeld zone) are pathognomonic.

Step 4: Eliminate other options. Rickets shows cupping, fraying, widening of metaphysis with reduced bone density. Osteopetrosis shows uniformly dense bones (marble bone disease). Metaphyseal dysplasia shows sclerotic metaphyses without the specific scorbutic signs.