In idiopathic scoliosis, the major indication for spinal fusion is a progressive curve with Cobb angle greater than how many degrees?

• A. 25°
• B. 35°
• C. 40°
• D. 50°

Answer: (C)

In idiopathic scoliosis, the decision to fuse the spine centers on progression of the curve and how large the Cobb angle is. The Cobb angle measures how curved the spine is, and if a major curve is getting worse over time, bracing can slow progression but often cannot stop it once the curve reaches a substantial size in a growing child. About 40 degrees is a common practical threshold at which surgeons consider spinal fusion to halt further progression and achieve lasting realignment and balance. The goal is to prevent the curve from getting larger and compromising function or appearance as the patient grows. Decisions also depend on skeletal maturity and how fast the curve is progressing, but the 40-degree mark is the standard indication cited here.