Ulnar Nerve Subluxation in the Overhead Athlete: Predicted Loss of Force Following Submuscular Versus Modified Subcutaneous Ulnar Nerve Transposition.

Purpose: Cubital tunnel syndrome and ulnar nerve subluxation are common issues for the overhead athlete and can be a considerable hindrance to their athletic performance. With the care of elite athletes in mind, there must be a balance between the relief of symptoms and preservation of capabilities. We quantified compromise of the flexor-pronator mass following modified subcutaneous versus submuscular ulnar nerve transposition. Methods: Eight cadaveric upper-extremity specimens were studied to determine the amount of muscle compromise following modified subcutaneous and submuscular ulnar nerve transposition. The muscles of the flexor-pronator mass were then identified, including the flexor carpi ulnaris, flexor digitorum superficialis, flexor carpi radialis, and pronator teres. The muscles of the flexor-pronator mass were dissected along their length, and a line was marked where the ulnar nerve would cross the muscle during transposition. Each muscle of the flexor-pronator mass was excised from the forearm. The volume of each muscle was estimated by the technique of volume displacement using a graduated cylinder. Results: There was a significant difference in the loss of muscle volume between the two techniques. This translates to the potential loss of force from the flexor-pronator mass. Submuscular transpositions resulted in 4.67× more muscle volume loss than the modified subcutaneous approach. Conclusions: When the ulnar nerve needs to be transposed, subcutaneous or modified subcutaneous ulnar nerve transposition results in less damage to the flexor-pronator mass. Clinical relevance: These findings aid in surgical decision making in the overhead athlete in order to preserve muscle volume and force of the flexor-pronator mass.