Swan neck deformity due to chronic radial collateral ligament injury of the little finger proximal interphalangeal joint.

We present seven cases of a relatively rare swan neck deformity resulting from chronic radial collateral ligament (RCL) injury of the proximal interphalangeal (PIP) joint in the little finger. All patients were middle-aged women (mean 51 years old, range 42-55), and the duration between the initial injury and surgery was 20 years (range 5-40). The chief complaint was painful snapping of the PIP joint. All patients had hyperextension and ulnar deviation of the PIP joint with mobile swan neck deformities that had not improved with conservative treatment. Radiographs revealed osteoarthritis and ulnar deviation of the PIP joints in all cases. We describe a method for reconstruction of both the palmar plate and the RCL of the affected PIP joint using a distally-based ulnar slip of flexor superficialis tendon. The prevention of PIP joint hyperextension was critical for successful resolution of symptoms; the aim of RCL augmentation was to prevent the recurrence of the deformity. LEVEL OF EVIDENCE: IV.