Ulnar Nerve Decompression With Subcutaneous Transposition

Abstract

Background:

Medial-sided elbow injuries are becoming increasingly common among throwing athletes due to overuse and increased specialization at early ages. High valgus stress and repetitive elbow flexion/extension during throwing not only affects the ligaments and dynamic support of the elbow, but commonly affects the ulnar nerve.

Indications:

Management of cubital tunnel syndrome is initially rest, therapy, and functional training; however, if conservative measures do not appropriately address the ulnar neuropathy, surgical decompression with subcutaneous transposition is a reliable treatment option.

Technique Description:

An incision is created over the medial epicondyle. The medial antebrachial cutaneous nerve is identified and protected. The ulnar nerve is identified and tagged with a vessel loop to allow for appropriate handling of the nerve. Decompression of the ulnar nerve begins proximally by spreading the tissues superficial to the ulnar nerve and splitting the fascia overlying it. Then, dissection deep to the nerve is performed. A small strip of the medial intermuscular septum will be used as a sling to hold the nerve securely in the transposed position. This is released proximally and the distal attachment to the medial epicondyle is left in place. Decompression is then continued distally by releasing the superficial fascia over the flexor carpi ulnaris (FCU) and a portion of the deep FCU muscle belly and fascia. The nerve is decompressed circumferentially, while preserving penetrating branches to the FCU as able. Ultimately, the ulnar nerve is decompressed 10 cm proximal and 10 cm distal to the medial epicondyle. The intermuscular septum is then pulled over the nerve, checked for appropriate length, and sutured in place both posterior and anterior to the ulnar nerve.

Results:

Symptom improvement after decompression and transposition is high (>90%); however, performance outcomes in overhead and throwing athletes is variable, and return to previous or higher level of play ranges from 60% to 90%.

Discussion/Conclusion:

Ulnar nerve decompression and transposition can reliably address underlying symptoms, but results are mixed for return to sport outcomes in overhead and throwing athletes.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

In this video we will demonstrate our preferred technique for ulnar nerve decompression with subcutaneous transposition in a throwing athlete. We will begin with the discussion of some of the background literature, we will then present a pertinent case, discuss surgical options, and demonstrate the surgical technique. Afterward we will discuss tips and tricks, postoperative management, and patient outcomes and return-to-play results.

It is well known that medial-sided elbow injuries are on the rise in throwing athletes of all ages. ³ This is predominantly due to high valgus stress and repetitive flexion that the elbow experiences during the throwing motion.^3,5 As with most overuse injuries, the initial treatment of cubital tunnel syndrome is nonoperative in the form of rest, therapy, and functional training. However, when conservative measures fail, surgical decompression may be a viable treatment option.^3,4 Although the diagnosis for cubital tunnel syndrome is typically based on clinical symptoms, electromyography (EMG) testing can be helpful. Patients who demonstrate severe ulnar nerve dysfunction on an EMG examination or have substantial weakness and muscle atrophy should be considered as candidates for earlier surgical intervention.

This patient is a 17-year-old right hand–dominant high school pitcher who has already committed to a Division I college. Symptoms include right arm medial elbow pain and a snapping sensation around the medial elbow when throwing. This has resulted in numbness in the fourth and fifth digits. On examination he has full range of motion and strength. His ulnar nerve demonstrates substantial subluxation and instability during flexion. There is no evidence of any triceps snapping. His examination for the medial ulnar collateral ligament and flexor pronator are all negative.

The three primary surgical options for cubital tunnel syndrome include decompression alone, decompression with subcutaneous transposition, or decompression with submuscular transposition.^1-3,7 In the overhead or throwing athlete, decompression with subcutaneous transposition is the preferred surgical technique as this relieves tension placed on the nerve and minimizes the risk of recurrent instability.^1,5 It also allows preservation of the flexor pronator musculature which is critical for performance in the throwing athlete.^2,3

The patient is positioned supine with the arm out on an armboard. A medial-based incision is created, centered over the medial epicondyle. Sharp dissection is carried out through the skin and electrocautery is used to dissect through the subcutaneous tissues down to the fascia. Once the fascia is reached, Metzenbaum scissors are used to elevate the tissue off the fascia and a Ray-Tec sponge can be used to bluntly dissect this plane and create a window for the surgical dissection and the transposition. When using this approach, the median antebrachial cutaneous nerve can be identified in the subcutaneous tissues at the distal and anterior aspect of the incision. It is left within these subcutaneous tissues and protected throughout the entirety of the case. The ulnar nerve is identified by palpation and here you can see it subluxating over the medial epicondyle. It is most easily located just proximal to the medial epicondyle, using careful dissection with scissors. Once the nerve is identified in one location, circumferential dissection is performed so that a vessel loop can be passed around the nerve. The vessel loop is tied to then allow for appropriate handling and control of the nerve throughout the case. Decompression of the ulnar nerve begins proximally by spreading the tissues superficial to the ulnar nerve and splitting the fascia overlying it. An index finger can be used to retract the nerve posteriorly and protect it during the anterior dissection. Ultimately, the nerve is decompressed for a total of 10 cm proximal to the medial epicondyle to allow adequate mobilization during the transposition. Once the superficial dissection is completed, dissection deep to the nerve is performed so that the nerve is circumferentially free and can be fully mobilized. The length of the decompression can be measured using the scissors and a ruler. Attention is then turned to the medial intermuscular septum. A small strip of the medial intermuscular septum will be used as a sling to hold the nerve in position anteriorly. Far proximal, the medial intermuscular septum is cut and then tagged with an Allis clamp. Careful dissection is performed while it is retracted distally. It is left attached to the medial epicondyle distally. The slip of medial intermuscular septum is then passed around the nerve and checked for appropriate length. Attention is then turned to the distal decompression. Initially, the superficial fascia over the flexor carpi ulnaris (FCU) is released. Deep to this, the FCU muscle is spread and released. The nerve is decompressed circumferentially, and great care is taken to protect and preserve any penetrating branches to the FCU. If any of these small motor branches continue to tether the nerve during transposition, then they can be selectively released and sacrificed. The deep fascia of the FCU is also split distally. This dissection is carried out for a total of 10 cm distal to the medial epicondyle so that the ulnar nerve, in total, is decompressed for 20 cm. That is, 10 cm proximal and 10 cm distal. The length of the distal decompression is measured in the same way.

Now that the nerve is fully decompressed, it is gently positioned anterior to the medial epicondyle. The arm is taken through an arc of flexion and extension to ensure that the nerve rests comfortably in this position without a tendency to subluxate posteriorly. The intermuscular septum is then pulled over the nerve and sutured posterior to it. This posterior suture will serve as the anchor for the sling, and it will prevent posterior subluxation of the nerve to keep it from flipping back into the cubital tunnel. After being secured posteriorly, it is then sutured down anteriorly. This is done in such a way that there is plenty of laxity in the sling so that it does not compress the nerve excessively. After the sutures are passed, a small instrument can be placed underneath the sling to ensure that it is not overtensioned and that there is plenty of space between the sling and the nerves so that the nerve can move freely without getting bound or kinked. Once again, mobility of the nerve is assessed, and the arm is taken through an arc of flexion and extension to ensure that there are no areas of compression or kinking of the nerve.

During surgery it is critical to remember to handle the ulnar nerve with great care to minimize the risk of development of a postoperative neuritis. Also, it is helpful to decompress the nerve for 10 cm proximal and 10 cm distal, for a total distance of 20 cm of decompression to minimize the chance of any abnormal bending or kinking of the nerve. Finally, it is important to preserve any branches of the FCU that can be preserved and ensure that the sling created with the intermuscular septum is created in a loose but secure fashion.

Postoperatively, patients are placed in a surgical dressing with a compressive sleeve. A sling is provided but can be weaned out of as tolerated. Elbow range of motion begins as soon as comfortable with the goal of achieving full range of motion by 2 to 3 weeks. Once full motion is obtained, and surgical incisions are healed, strength training begins and is progressed as tolerated. Functional therapy and return to throwing begin around 6 weeks, with a goal of getting athletes back to sport around 12 weeks postoperative.

Overall, ulnar nerve decompression with subcutaneous transposition demonstrates relatively high rates of success with greater than 90% of patients experiencing symptom improvement. ⁶ Return-to-play rates have been quite variable and have been reported as anywhere from 60% to 90%; however, return to same level of play rates are somewhat lower. ⁴ Ultimately, ulnar nerve decompression and transposition reliably addresses underlying symptoms but results can be mixed when it comes to return to sports, particularly for overhead athletes and throwers.