Modification of the Zancolli Lasso Procedure for Simultaneous Correction of Wartenberg's Sign

Ulnar nerve injury initiates an imbalance between the intrinsic muscles and extrinsic extensors of the ring and small fingers, which leads to the characteristic hyperextension of the metacarpophalangeal (MP) joints and flexion of the proximal interphalangeal joints of these 2 digits-commonly referred to as the ulnar claw hand. In addition to these changes in the static posture of the hand, ulnar nerve palsy severely impairs grasp due to deficient active MP joint flexion. In most cases, motor balance can be restored by preventing MP joint hyperextension and augmenting MP joint flexion using the Zancolli lasso procedure (ZLP). Ulnar neuropathy can cause a second motor imbalance between the ulnar intrinsics and the extensor digit minimi leading to an abduction deformity of the small finger known as Wartenberg's sign. The inability to adduct the small finger can be a great source of frustration to patients. Using a cadaveric biomechanical model, we have developed a simple modification of the Zancolli lasso procedure that simultaneously corrects claw deformity and Wartenberg's sign and we report its efficacy in 2 clinical cases.