Review Question - QID 211908

The patient has a swan neck deformity of his right index finger most likely due to cerebral palsy. A central slip (structure labeled C) tenotomy can help correct this deformity.

A swan neck deformity is characterized by hyperextension of the PIP joint with concomitant flexion of the DIP joint. There are several causes of this deformity with the most common being a lax volar plate leading to intrinsic imbalance at the PIP joint (extensors > flexors). Swan neck deformities occur in cerebral palsy due to the volitional overpull of the extrinsic finger extensors and/or spasticity of the intrinsics. Treatment involves initial splinting to prevent PIP hyperextension. Operative management involves volar plate advancement with a central slip tenotomy (Fowler tenotomy) to correct this intrinsic imbalance.

Van Heest and House described a technique by securing the lateral band volarly with the volar plate or a slip of FDS tendon for treatment of swan neck deformity in cerebral palsy. The authors state that overactivity of the extrinsic and intrinsic muscle systems causes PIP joint hyperextension with dorsal subluxation of the lateral band. They cite that both the intrinsic and extrinsic pathophysiology is addressed by redirecting the conjoined lateral band volar to the axis of the PIP joint. The authors conclude that rerouting the lateral band volar to the PIP joint axis effectively rebalances the joint and is an effective surgical treatment for locking or progressive flexible swan neck deformities due to cerebral palsy.

Carlson and Carlson performed a review of swan neck deformity in patients with cerebral palsy. The authors noted that the deformity typically arises from hand intrinsic muscle spasticity or overpull of the digital extensors. They cite that intrinsic lengthening can be used to treat intrinsic muscle spasticity, whereas central slip tenotomy is employed when digital extensor overpull is the deforming force. The authors conclude that accurate diagnosis and application of the proper surgical technique are essential when treating swan neck deformity in patients with cerebral palsy.

Figure A reveals a clinical photograph of a patient with a swan-neck deformity. Figure B reveals an unlabeled figure of the extensor tendon anatomy of the digit. Illustration A is the labeled version of Figure C.

Incorrect Answers:
Answer 1: A refers to the terminal extensor tendon
Answer 2: B refers to the lateral band
Answer 4: D refers to the lateral slip of the common extensor tendon
Answer 5: E refers to the lumbrical tendon