Cubital tunnel syndrome: anterior transposition as a logical approach to complete nerve decompression.

In it's native position, deep to Osborne's ligament, within the retrocondylar groove of the elbow, the ulnar nerve courses with a significant lever distance posterior to the elbow axis of rotation. In this position, flexion of the elbow places longitudinal traction and local compression forces on the nerve. This biomechanical consideration, as well as variations in anatomy, may potentially contribute to a decrease in the nerve's microcirculation and partial pressure of oxygen, leading to cubital tunnel syndrome. Anterior transposition of the ulnar nerve at the elbow for cubital tunnel syndrome will eliminate natural as well as pathological traction and compression forces; the procedure relieves the nerve of potential microcirculation compromise. Risks of mobilizing the nerve for transposition, however, include iatrogenic ischemia from segmental separation of the nerve from its mesentery-like extrinsic blood supply. Intrinsic interstitial "step-ladder" vessels within the substance of the ulnar nerve allow it to be separated from its extrinsic circulation safely, making anterior transposition a logical and reasonable choice for cubital tunnel syndrome requiring operative intervention.