Step Cut Ulnar Shortening Osteotomy for Ulnar Impaction Syndrome

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The step-cut ulnar shortening osteotomy for the treatment of ulnar impaction syndrome is a safe, reliable, and less expensive technique that uses a 7-hole 3.5-mm standard neutralization plate and a lag screw for fixation, thus avoiding the need for the special instrumentation that other ulnar shortening techniques require.

The extra-articular ulnar shortening osteotomy is a common and widely accepted procedure for the surgical treatment of ulnar impaction syndrome, or ulnocarpal abutment syndrome, which is characterized as a degenerative condition of the ulnar side of the wrist that is related to excessive load-bearing between structures of the ulnocarpal joint. Ulnar impaction syndrome is frequently associated with positive ulnar variance, which can be congenital or posttraumatic.

A variety of surgical techniques for this osteotomy, transverse or oblique, have been developed using special instrumentation (jigs, cutting guides, and shortening systems) and several fixation techniques. However, no method has demonstrated clinical superiority. The concept of the step-cut ulnar shortening osteotomy was designed to overcome the morbidity associated with suboptimal rotational control (nonunion or malunion) when performing a transverse or oblique osteotomy technique and to avoid the need for, and thus eliminate the cost of, special equipment.

The step-cut ulnar shortening osteotomy is performed freehand with its long arm oriented in the coronal plane and the short arms perpendicular to the long axis in the axial plane. Stable fixation is performed with a volar 3.5-mm standard neutralization plate and a lag screw. The osteotomy is designed using the 7-hole 3.5-mm standard neutralization plate as a template. The step-cut osteotomy provides larger contact surfaces and better rotational control than transverse or oblique osteotomies without the use of special equipment.

The goal of the osteotomy is to unload the ulnocarpal joint by shortening the ulna by only a few millimeters and not necessarily to reduce ulnar variance to neutral or negative. It is important to resect the same amount of bone at both proximal and distal ends of the osteotomized ulna.

We present the surgical technique of a step-cut ulnar shortening osteotomy for the treatment of ulnar impaction syndrome.