Feasibility of a fascial flap to avoid anterior transposition of unstable Ulnar nerve: A cadaver study.

Background: Compression of the ulnar nerve at the elbow is the second most frequent site of nerve compression in the upper limb. Upon release, anteposition of the nerve may be necessary to avoid dislocation of the latter when unstable. Numerous techniques are described in the literature (subcutaneous transposition, intramuscular transposition, subfascial transposition, medial epicondylectomy …), none of which is without complications. Based on Han's work, the authors propose a technique of covering the ulnar nerve with epicondylar fascial flap, avoiding transposition, but ensuring good stability of the ulnar nerve. Methods: As part of the SICM (Italian Society of Hand Surgery) cadaver dissection course (ICLO, Verona, Italy) the authors dissected 36 elbows, of which 20 presented subluxation of the ulnar nerve after its decompression. The fascial flap was therefore made on these 20 elbows, coming from 14 different donors (9 men, 5 women) with an average age of 78 years. The diameter of the ulnar nerve was then measured (at the level of the passage in the cubital canal), the diameter of the newly formed canal, the difference between the two previous measurements (residual space in the flexed elbow canal), and it was verified whether the ulnar nerve was unstable once covered by the flap. Results: The mean diameter of the ulnar nerve was 5.1 mm (range 4-6), while the mean diameter of the neo-canal was 10.1 mm (range 8-11) in elbow extension and 8.9 mm (range 7-10) in elbow flexion. The remaining space in the flexed elbow canal was 3.8 mm (range 3-5).In none of the 20 cases the ulnar nerve was dislocated after having made the fascial flap. Conlusions: In light of the results obtained, the authors think that the use of the epicondylar fascial flap may be a solution to keep in mind to avoid dislocation of the ulnar nerve when it becomes unstable following its decompression. This work obviously needs clinical confirmation on living patients. Level of evidence: V.