Subcutaneous Transposition of the Ulnar Nerve

The medial epicondyle may act as a fulcrum causing deformation of the ulnar nerve during elbow flexion. Furthermore, ulnar neuropathy can be potentiated by dynamic instability of the ulnar nerve around and over the medial epicondyle. Anterior transposition techniques were designed to eliminate traction on the nerve from the medial epicondyle or mechanical irritation in the presence of dynamic instability. Subcutaneous anterior transposition has been advocated as a less morbid alternative to deeper transposition techniques (i.e. intramuscular or submuscular) as it requires less dissection. Multiple techniques have been reported to maintain the nerve in its subcutaneous position after transposition, utilizing a fasciodermal sling from the flexor-pronator mass, an adipose flap, the medial intermuscular septum, or even Osborne’s ligament. Care must be taken with anterior transposition to avoid creation of new sites of compression, particularly at the medial intermuscular septum and the flexor carpi ulnaris fascia. Subcutaneous ulnar nerve transposition has been found to be comparable to in situ decompression as well as submuscular and intramuscular transposition techniques in several randomized trials and large outcomes series.