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Cubital tunnel syndrome is a condition that affects the ulnar nerve as it crosses the medial elbow through the retrocondylar groove. It is the second most common compressive neuropathy, causing tingling and numbness in the ring and small fingers. In advanced cases of symptomatic cubital tunnel syndrome, weakness, altered dexterity, and atrophy of the intrinsic muscles of the hand may develop.1 Cubital tunnel syndrome can be treated with either a cubital tunnel release or an ulnar transposition. In this case, the former is demonstrated on a cadaveric arm.
The ulnar nerve originates from the C8–T1 nerve roots, forming part of the medial cord of the brachial plexus. It descends down the arm medial to the brachial artery, up until the insertion point of the coracobrachialis muscle. It then pierces the medial intermuscular septum and enters the posterior compartment of the arm. It runs along the posteromedial aspect of the humerus, passing behind the medial epicondyle in the cubital tunnel. The roof of the cubital tunnel is formed by Osborne’s ligament and the flexor carpi ulnaris fascia. The floor of the tunnel is formed by the posterior and transverse bands of the medial collateral ligament and elbow joint capsule. The medial epicondyle and the olecranon process form the walls of the cubital tunnel. In the cubital tunnel, the ulnar nerve is palpable by hand. After passing through the cubital tunnel, the ulnar nerve enters the anterior compartment of the forearm between the two heads of flexor carpi ulnaris. It runs through the forearm between the flexor digitorum superficialis laterally and the flexor digitorum profundus medially. In the forearm, the ulnar nerve gives off several branches: muscular branches, palmar branches, dorsal branches, and articular branches. The ulnar nerve enters the palm of the hand via Guyon’s canal. In the hand, it gives off several additional branches including the superficial sensory branch, the deep motor branch, and additional articular branches.
Functionally, the ulnar nerve provides sensory innervation to the fifth digit, the medial half of the fourth digit, and the corresponding parts of the palm. Additionally, the ulnar nerve’s motor function controls the fine movements of the fingers via the intrinsic muscles of the hand.
Most commonly, there are three sites of ulnar nerve entrapment in the elbow that lead to cubital tunnel syndrome. Proximally, the ulnar nerve may become entrapped within the arcade of Struthers (the hiatus in the medial intermuscular septum). Moving distally, the ulnar nerve may also become entrapped between Osborne’s ligament and the medial collateral ligament. Most distally, the ulnar nerve may become entrapped in the aponeurosis between the two heads of flexor carpi ulnaris.
Surgically, there are two broad approaches to cubital tunnel syndrome. The first approach is to release the nerve where it lies in an in situ release (neuroplasty of ulnar nerve). The second approach is a transposition, which involves neurolysis of the ulnar nerve and transposition anteriorly. This surgical video and accompanying article only deal with the former approach: in situ release of the ulnar nerve. Several techniques fall under the category of in situ release of compressive ulnar neuropathy. These include the extensile-open, the mini-open, and the endoscopic techniques.2 The difference between the extensile-open and the mini-open techniques is limited to the length of the incision. In the extensile-open technique, an incision is made centered on the medial epicondyle of the elbow. The incision is made 6–8 cm proximally to the medial epicondyle to a distance 6–10 cm distally to the medial epicondyle. The mini-open technique uses the same incision line, but the incision can be made smaller both proximally and distally. The mini-open technique for cubital tunnel release is performed in this video and discussed below in more detail.
The third surgical technique under the category of in situ ulnar nerve release is the endoscopic technique.3 The potential advantages of an endoscopic cubital tunnel release over an open procedure to surgically treat cubital tunnel syndrome include smaller incision, less surgical pain, earlier recovery, minimized manipulation of the ulnar nerve, and reduced risk of nerve devascularization. Yet, several contraindications may exist that hinder the use of the endoscopic technique. Severe cubital valgus or elbow deformity, osteoarthritis of the elbow, or recurrent ulnar nerve compressions after previous surgeries are all contraindications for endoscopic cubital tunnel release. Additionally, if endoscopic release is performed and the ulnar nerve begins to sublux over the medial epicondyle, an incision may need to be made to perform a medial epicondylectomy or anterior nerve transposition.
Before the operation begins, the patient should be kept supine on the operating table. The operative limb is extended across a hand table. Standard preparation and draping of the limb should be performed, and a sterile tourniquet should be applied.
To begin an open, in situ ulnar nerve release, the patient’s elbow should be flexed slightly and the shoulder externally rotated, looking at the posteromedial aspect of the elbow behind the medial epicondyle. Before making the incision, it is important to examine the position of the ulnar nerve and to ensure that it lies stably behind the medial epicondyle. Examination of the ulnar nerve before making the incision allows the surgeon to determine if the ulnar nerve is subluxing over the medial epicondyle into the surgical field. A subluxing ulnar nerve preoperatively or postoperatively may be an indication for an ulnar nerve transposition as opposed to the in situ release. After careful examination of the ulnar nerve and determination of its stability behind the medial epicondyle, the incision can be made.
After the incision is made, the tissue should be dissected down to the level of the medial epicondyle to find the ulnar nerve. The ulnar nerve will be palpable before it is visible behind the medial epicondyle. Branches of the medial antebrachial cutaneous nerve may be found to be crossing the medial epicondyle and the ulnar nerve, and should be identified and retracted.
With the ulnar nerve palpated, it is sharply incised longitudinally behind the medial epicondyle. Once the ulnar nerve is clearly exposed, the decompression can begin. Proximally, Metzenbaum scissors can be used to carefully decompress the nerve. Distally, the Metzenbaum scissors can similarly be used to release the ulnar nerve distally through the cubital tunnel, under Osborne’s ligament, and through the aponeurosis of the two heads of flexor carpi ulnaris.
Once the ulnar nerve is released, the elbow joint is ranged in flexion and extension, and the ulnar nerve is observed. The nerve may roll or perch over the epicondyle, but it should not sublux or dislocate. Flexing and extending the elbow ensures the ulnar nerve’s stability after it has been released.
The wound is washed and closed in layers. A soft dressing is applied.
Use of the operative limb for activities of daily living is allowed immediately after surgery. However, strenuous activity is discouraged for a period of 2–4 weeks postoperatively until the surgical wound is healed and surgical site pain has resolved.
Several studies have reported on the outcomes of the cubital tunnel release procedure. Generally, regardless of the surgical treatment employed, release of the ulnar nerve at the elbow improves symptoms of pain, numbness, and tingling within and outside of the elbow. As discussed previously, cubital tunnel release can be performed with an in situ release or transposition. Bacle et al. reviewed 375 patients undergoing surgery for ulnar nerve entrapment. Regardless of surgical technique, 90% of patients were cured or showed improvement.4 Neither of the techniques aggravated symptoms, and the study concluded that surgery was effective in treating cubital tunnel syndrome. Transposition proved to be as effective as in situ decompression.
To some degree, however, transpositions were associated with more complications and slower recovery. Results from studies conducted by Bartels et al., Nabhan et al., and Caliandro et al. also support these findings.5–7 More specifically, research has compared results of the different techniques used for in situ ulnar nerve release. In a meta-analysis comparing results of 556 endoscopic versus 425 open cubital tunnel release procedures, Aldekhayel et al. concluded that the two methods of in situ cubital tunnel release produce similar outcomes, complication profiles, and reoperation rates.3 In both groups, approximately 80% of patients experience “good” or “excellent” results as defined by specific study criteria.
To date, the literature does not seem to agree on a superior method for repair of ulnar nerve entrapment. The choice of surgical technique to repair cubital tunnel syndrome remains in question and should be an individualized decision based on the surgeon’s discretion.
Nothing to disclose.
- Staples JR, Calfee R. Cubital tunnel syndrome: current concepts. J Am Acad Orthop Surg. 2017;25(10):e215-e224. doi:10.5435/JAAOS-D-15-00261.
- Novak CB, Mackinnon SE. Selection of operative procedures for cubital tunnel syndrome. Hand (N Y). 2009;4(1):50-54. doi:10.1007/s11552-008-9133-z.
- Aldekhayel S, Govshievich A, Lee J, Tahiri Y, Luc M. Endoscopic versus open cubital tunnel release: a systematic review and meta-analysis. Hand (N Y). 2016;11(1):36-44. doi:10.1177/1558944715616097.
- Bacle G, Marteau E, Freslon M, et al. Cubital tunnel syndrome: comparative results of a multicenter study of 4 surgical techniques with a mean follow-up of 92 months. Orthop Traumatol Surg Res. 2014;100(4)(suppl):S205-S208. doi:10.1016/j.otsr.2014.03.009.
- Bartels RHMA, Verhagen WIM, van der Wilt GJ, Meulstee J, van Rossum LGM, Grotenhuis JA. Prospective randomized controlled study comparing simple decompression versus anterior subcutaneous transposition for idiopathic neuropathy of the ulnar nerve at the elbow: part 1. Neurosurgery. 2005;56(3):522-530. doi:10.1227/01.neu.0000154131.01167.03.
- Nabhan A, Ahlhelm F, Kelm J, Reith W, Schwerdtfeger K, Steudel WI. Simple decompression or subcutaneous anterior transposition of the ulnar nerve for cubital tunnel syndrome. J Hand Surg Br. 2005;30(5):521-524. doi:10.1016/j.jhsb.2005.05.011.
- Caliandro P, La Torre G, Padua R, Giannini F, Padua L. Treatment for ulnar neuropathy at the elbow. Cochrane Database Syst Rev. 2016;(11):CD006839. doi:10.1002/14651858.CD006839.pub4.
Cite this articleZachary Herman, Asif M. Ilyas, MD, FACS. Cubital tunnel release (cadaver). J Med Insight. 2021;2021(206.4). https://doi.org/10.24296/jomi/206.4
Table of Contents
- Release Proximal Nerve
- Release at Cubital Tunnel
- Release Distally
My name is Asif Ilyas. I'm a Professor of Orthopaedic Surgery and the Program Director of Hand Surgery at the Rothman Institute at Thomas Jefferson University in Philadelphia. Today we will be going over a cubital tunnel release procedure. Cubital tunnel syndrome is a very common compressive neuropathy of the upper extremity. It's the second most common compressive neuropathy after carpal tunnel syndrome, and fundamentally, it involves compression of the ulnar nerve as it traverses the cubital tunnel, which is behind the medial epicondyle of the elbow. When you have a symptomatic cubital tunnel syndrome, which you will notice is numbness and tingling in your small and part of your ring finger, and in advanced cases, you'll also develop some weakness, and altered dexterity, and even atrophy of the intrinsics of your hand.
There's 2 broad ways to approach cubital tunnel syndrome. Surgically, one is to do an in situ release where the nerve is released right where it lies - also known as a neuroplasty of the ulnar nerve - or the second broad way of treating this is with a transposition where you actually neurolyse the ulnar nerve and then transpose it anteriorly. Now within each of those broad categories, there's subcategories, so for this video, we will be looking at specifically a cubital tunnel release. So cubital tunnel release can also be further broken up into an extensile-open, a mini-open, and an endoscopic technique, and I'll be showing you the mini-open technique for decompressing the ulnar nerve in the cubital tunnel.
Okay, so now we're going be addressing ulnar neuropathy of the elbow, also known as cubital tunnel syndrome. You'll notice the arm is flexed slightly, externally rotated. I'm looking at the posteromedial - posteromedial aspect of the elbow. The ulnar nerve is going to be right behind the medial epicondyle, and it is palpable in the specimen here. Now to manage, surgically, ulnar neuropathy of the elbow, you have 2 ways you can approach this. You can do what is called an in situ cubital tunnel release or an ulnar nerve transposition with neurolysis. Either way, the incision is placed in this aspect of the elbow, behind the medial epicondyle.
So I'm going to mark out both incisions to kind of share - to discuss how we go about this. So if you're doing a - a ulnar nerve transposition, you bring the elbow straight. You feel the epicondyle here. The tendency is to bring the incision anterior to the epicondyle, but recognize that you'll be away from your nerve and also increase the odds of injury inadvertently to the branches of the medial antebrachial cutaneous nerve.
So with the elbow extended, I find it helpful to make a relatively straight incision. Behind the elbow, which is the path of the ulnar nerve. If I'm doing an ulnar nerve transposition, centered on the medial epicondyle, I'll - my incision will go anywhere from 6 to 8 cm distally, and similarly, about 6 to 8 cm, maybe 6 to 10 cm, proximally. Now, if I'm doing a cubital tunnel release, I can use the same incision; however, I can also make a smaller incision - what I refer to as the mini-open technique. And I'll use the same location on my incision, but I'll flex up the arm a little bit more to get a sense of where it is. And I place the incision directly - behind the medial epicondyle - like so. If I'm taking the transposition, I'll go the full length.
So we're going to proceed with a cubital tunnel release procedure through a mini-open technique. So here's my incision. We're going to get started. Luckily, besides the nerve itself, the ulnar nerve, there's not too many significant hazards, and one of the advantages of placing the incision somewhat posteriorly - I avoid branches of the medial antebrachial cutaneous nerve, which typically come across the epicondyle and just anterior to it. So I'm posterior to it, so I should be away from those hazards. I'm intentionally making my incision a little bit anterior to the epicondyle to not inadvertently injure the ulnar nerve. Now it's helpful to examine the nerve beforehand and make sure the ulnar nerve is stable, behind the epicondyle. That's important for a couple reasons. One, if it's unstable, it may have subluxed into your surgical field. And two, it helps in your decision-making of whether you do a transposition versus an in situ release. Our understanding of the evidence so far is that one has not been shown to be superior than the other with the current best evidence available to us. However, one of the reasons to do a primary transposition instead of an in situ release is a subluxing - a preoperatively or postoperatively subluxing.
I'm going to change retractors from a Gelpi to a Weitlaner, which I think will help with our visualization. Okay, so - there’s a couple ways to find the nerve quite easily. One is just directly behind the medial epicondyle, or two is behind the intermuscular septum. So here's the nerve, right there. It's very superficial. It's quite easy to find. Now I'm going to expose it a little bit better, but just to get a relationship of the epicondyle - ulnar nerve coming across it.
So, remember when you're doing a cubital tunnel release surgery - you're not neurolysing the nerve, you're not doing a transposition. You're doing a neuroplasty. There's a tendency, or a habit, with this surgery for people to do a neurolysis 360. What that does is 2 things. It creates 2 problems. Problem number 1 is it makes the nerve unstable. And number 2, it devascularizes the nerve. Think of a cubital tunnel release no different than a carpal tunnel release, where you're just releasing it where it lies. Now I changed my scissors to a Metz. And once I have it adequately exposed proximally, I'll just slide and make sure we have a great view of it above and below. I'll do a release right where it lies. So that's the easy part of the release - is the proximal part. So if you take a look now - you'll see the nerve - nicely - released - no more fascia. What I released was the arcade. Okay, so now - we're going to do the distal part of the release. I'll just give myself a little bit more skin.
Good. Once the nerve has been decompressed proximally, we can work our way distally. And the next thing you'll find - just to orient everyone, this is the medial epicondyle. This is the olecranon. This is the ulnar nerve. So, we're going to work our way distally. And typically, the path of the nerve across the cubital tunnel, or under Osborne's ligament, is the tightest. And that's where we're working now. And whenever I cut, I always make sure that I have the nerve in view. And again, I'm not doing a - neurolysis of the nerve, I'm doing a neuroplasty.
And I'm going to take this distal, and the question always comes up - how distal do you go? You go until you get to the 2 heads of FCU, the flexor carpi ulnaris, and you make sure that it is decompressed as it travels through. So here's a good view of that plane, just to show you. I'm going to grab a Freer for a second. So just to orient, everybody - so, you'll see the nerve deep, and you see the path of the nerve underneath it. You'll see the fascia of the FCU starting, and my retractors are above that fascia - the fascial plane. And the release that we like to do - is basically - at this level - right here. Let me see if I can put a retractor there to show that a little bit better. It's hard to do by myself here. Unfortunately, I should have had somebody. Just to show everyone the plane. That's the plane below. That's the plane above. And the release is like this. Gentle slide. And cut, and the nerve is free. And you want to visualize - going deep. Make sure it's adequately decompressed. There's often a deep investing fascia - you want to confirm that it is released.
Once adequately released, and satisfied that it's released, you range the elbow - flexion and extension - to make sure that the ulnar nerve does not sublux, or dislocate, over the medial epicondyle. A little bit of rolling and perching is typical, but you do not want it to sublux. And you'll see here in this case that the ulnar nerve is very stable. Once released, you'll see how it tends to pouch more and almost roll freely more, but it should not dislocate or sublux out.