Question

Progression of congenital scoliosis is least likely in which of the following vertebral anomalies:

• A. Fully segmented hemivertebra
• B. Wedge vertebra
• C. Block vertebra
• D. Unilateral unsegmented bar with hemivertebra

Hint:

No growth plates means no uneven growth; the fully fused block vertebra stays put.

Answer 1

The Correct Option is C

Step 1: Understand the principle. In congenital scoliosis the curve gets worse only when the two sides of the spine grow at different rates. The risk of progression depends on how much asymmetric growth potential the anomaly leaves behind.

Step 2: Rank the anomalies by growth imbalance. A unilateral unsegmented bar combined with a contralateral hemivertebra is the worst: one side cannot grow at all while the other side has an extra growing wedge, giving the maximum imbalance and the fastest progression.

Step 3: Look at the next worst. A fully segmented hemivertebra has open growth plates on both sides of the extra wedge, so it keeps adding length on one side and produces a steadily progressive curve. A wedge vertebra has an intermediate, lower progression risk.

Step 4: Identify the safest. A block vertebra is two or more vertebrae fully fused together. There are no active growth plates between them and the fusion is symmetric, so there is essentially no asymmetric growth. This anomaly is the least likely to progress.

Step 5: The question asks for the lowest progression risk, so the answer is Block vertebra (option C).