What is the most common cause of hammer toe?

• A. Extensor substitution
• B. Dorsal contracture
• C. Flexor stabilization
• D. Tendon imbalance

Answer: (C)

Hammer toe arises when the toe’s tendons are out of balance and the flexor tendons become the dominant force, stabilizing the toe in a flexed position at the proximal interphalangeal joint. This flexor stabilization pulls the PIP joint into flexion and maintains the toe that way, while the extensor mechanism and intrinsic muscles can’t fully counteract it. That pattern—toe flexion at the PIP due to persistent flexor pull—is the hallmark of the deformity, making flexor stabilization the most common cause. Patterns driven by extensor overactivity or dorsal tightness would produce different deformities, and tendon imbalance is a broader description that doesn’t specifically capture the usual mechanism as clearly.