Swan Neck Deformity

Straight Middle Joint, Bent Tip

PIPJ hyperextension + DIPJ flexion: the reverse of boutonnière. Multiple causes: volar plate laxity at PIPJ, FDS rupture, intrinsic muscle spasticity, mallet finger (secondary: extensor imbalance), RA (most common cause of bilateral swan neck). Named for the graceful curve resembling a swan's neck.

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