Introduction Indications decompression and/or transposition of the ulnar nerve. Ulnar removal of loose bodies ORIF of the ulnar coronoid process ORIF of the medial humeral condyle and epicondyle debridement and reattachment of common flexor wad for medial epicondylitis Internervous plane Proximally between brachialis (musculocutaneous nerve) triceps (radial nerve) Distally between brachialis (musculocutaneous nerve) pronator teres (median nerve) Preparation Anesthesia general supraclavicular or infraclaviclar nerve block Position supine with arm flexed and supported by arm board over the patient Tourniquet applied to upper arm Approach Incision curved incision 8 to 10 cm long on the medial aspect of the elbow centered over the medial epicondyle Superficial dissection incise the fascia over the ulnar nerve starting proximally isolate nerve along the entire length of the incision expose the common flexor origin on the medial epicondyle develop brachialis and PT interval avoid the median nerve which enters PT near the midline if necessary can perform osteotomy of the medial epicondyle osteotomy is reflected distally ensure retained MCL ligament into osteotomy fragment develop brachialis and triceps interval Deep dissection incise capsule and medial collateral ligament Extension local abduction of forearm opens medial aspect of joint can dislocate laterally by dissecting off joint capsule and periosteum proximal anterior surface of distal fourth of humerus can be exposed by developing plane between brachialis and triceps distal limited by the branches of the median nerve Dangers Ulnar nerve is at risk during approach must be dissected out to ensure protection Median nerve aggressive traction on the osteotomy fragment can cause a traction injury to the median and anterior interosseous nerves