Subperiosteal elevation of the ulnar nerve-Anatomical considerations and preliminary results.

Mobilisation of the ulnar nerve often leads to perineural scarring. About 30 years ago, B.F. Korosec, M.D., developed a novel surgical approach to the distal humerus combined with osteotomy of the olecranon, which avoids visualisation or direct manipulation of the ulnar nerve. The main advantage of his technique lies in subperiosteal elevation of the ulnar nerve together with all structures of the cubital tunnel. In the present study, anatomical dissections of distal humerus structures were performed in a cadaver to define individual steps of the technique introduced by Dr. Korosec. Ten phases of the procedure were identified. Ten patients (4 males and 6 females) with type 13-C and 13-B fractures of the distal humerus (AO/ASIF) were operated on. The patients showed no clinical signs of ulnar nerve injury before surgery. During the operation, the ulnar nerve was electrically stimulated at the axilla and compound muscle action potentials were continuously recorded from hypothenar muscles. Latency and amplitude of the potentials were monitored. Analysis of these data using the unpaired t-test for median values revealed no statistically significant differences between individual stages of the operation (p<0.00625). An amplitude decrease accompanied by a latency increase by more than 10% over the baseline value was found to indicate impending nerve damage. The novel approach to the distal humerus presented in this article is a safe procedure.