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Cubital tunnel syndrome is one of the most common compression neuropathies affecting the upper extremity. Physical exam findings include loss of sensation, muscle weakness, and clawing of the fingers. More severe cases also show irreversible muscle atrophy, hand contractures, and loss of function. There are several approaches to treating cubital tunnel syndrome. Here, a subcutaneous anterior transposition was performed on this patient. The patient’s ulnar nerve subluxed upon elbow flexion and extension upon physical examination, which was a primary indication for choosing this surgical approach over other techniques. This procedure not only decompresses the affected nerve but also transposes the nerve anterior to the medial epicondyle so as to relieve strain on the nerve upon the full range of motion of the elbow.
This is a case of a 42-year-old female presenting with numbness in the ring and small fingers for several months that is worst at night or when sitting in a chair. Over time the patient notes tenderness in the inside part of the elbow and altered hand dexterity and strength.
Cubital tunnel syndrome is the second most common compression neuropathy affecting the upper extremity after carpal tunnel syndrome.1 It affects approximately 1% of the general population in the US. However, information on the epidemiology of cubital tunnel syndrome is limited compared with that of carpal tunnel syndrome. Unlike carpal tunnel syndrome, active disease surveillance of cubital tunnel syndrome in the US is lacking, which has implications for establishing standard guidelines on its diagnosis and treatment.2 In addition to affecting the patient’s activities of daily living, cubital tunnel syndrome also carries an additional economic burden. In a study conducted by Juratli et al., nearly half of the workers with this condition received disability benefits before diagnosis.3
First-line treatment for cubital tunnel syndrome is typically nonoperative. When conservative treatment fails to relieve symptoms, however, surgical intervention is needed. There are a variety of different surgical procedures that can be performed. Here, an anterior subcutaneous ulnar nerve transposition is performed on this patient.
Physical exam findings will reveal decreased sensation in the ring and small fingers, and muscle weakness in the interossei of the hand. In more advanced cases, clawing of the ring and small fingers may also be evident upon inspection of the hand. Additionally, there are several tests that can be performed on the hand to help in the diagnosis of cubital tunnel syndrome. A positive Froment’s sign occurs when the patient’s interphalangeal joint of the thumb flexes when asked to pinch a flat object, such as a piece of paper. A positive Wartenberg’s sign will show persistent abduction of the fifth digit during attempted adduction of all digits. Lastly, provocative tests such as the Tinel sign, where slight percussion over the nerve elicits a tingling sensation, and reproduction of symptoms upon flexion of the elbow, can also be performed to support this diagnosis.
Patients with cubital tunnel syndrome experience a range of symptoms such as discomfort, muscle weakness, and numbness in the ring and small fingers. Patients may also report night symptoms such as awakening as a result of sleeping with their elbow in a flexed position. Early symptoms are primarily sensory with motor changes occurring later. In more severe cases, loss of function, hand contractures, and irreversible muscle atrophy may also be evident if the patient is left untreated.4
Nonoperative therapies such as pain relief, inflammation reduction, and rehabilitation work for patients 50% of the time.5 These include NSAIDs, corticosteroid injections, and nighttime extension splints, which have all shown efficacy. Other measures such as elbow pads, physical therapy, and avoidance of provocative activities can also relieve symptoms.
Surgical intervention is only considered when conservative treatments fail to treat the patient’s symptoms. There are a variety of different surgical procedures to treat cubital syndrome. Among these are open or endoscopic ulnar nerve decompression, ulnar nerve transposition, and medial epicondylectomy. Simple decompression and anterior transposition (subcutaneous or submuscular) are the most common surgical treatments for cubital tunnel syndrome. However, there is a lack of consensus on determining the best and optimal surgical treatment for cubital tunnel syndrome. Thus, the choice of procedure is often determined by a variety of different factors: the severity of nerve compression, nonspecific patient factors, and surgeon preference.1
As mentioned above, there is no standard approach to treating cubital tunnel syndrome surgically. However, in situ decompression such as a cubital tunnel release is generally considered the first surgical choice. However, when there is baseline ulnar nerve instability, then transposition may be better. In this case, it was evident upon physical examination that the patient’s ulnar nerve subluxed upon elbow flexion and extension. This key finding was the primary indication for performing an ulnar nerve transposition versus an in situ cubital tunnel release.
Before incision, patients are typically given either general or regional anesthesia and are injected with Marcaine with epinephrine to minimize bleeding and pain postoperatively. During blunt dissection to the level of the ulnar nerve and cubital tunnel, the medial antebrachial cutaneous nerve was first identified and protected throughout the procedure, as injury to this nerve is common with this approach. Crossing veins in the surgical field were cauterized to prevent hematoma formation and bruising postoperatively.
Dissection of the ulnar nerve was started posterior to the medial epicondyle where the nerve is more easily mobilized and identified. The ulnar nerve was mobilized by releasing its fascia first distally and then proximally with care not to injure surrounding vessels and nerves. The intermuscular septum was then identified and mobilized to prevent any undue tension on the ulnar nerve upon transposition.
The cubital tunnel was first closed before transposing the ulnar nerve in order to prevent subluxation or dislocation. In order to keep the ulnar nerve in an anteriorly subcutaneous transposed position, a mattress suture technique was used to attach the fascial sling to the anterior skin flap. Direct visualization and flexion of the elbow can confirm that the fascial sling is secure enough without compressing the ulnar nerve.
The wound was washed and closed with sutures in a layered fashion. Postoperatively, a sling was provided for protection and comfort. The patient was able to range the arm and resume activities of daily living immediately. However, it was advised to the patient that strenuous activity should be avoided for at least 2–6 weeks postoperatively until the wound is fully healed. After the sling is removed, physical therapy is generally advised to allow for the full range of motion of the elbow joint.
There are few complications associated with anterior transposition of the ulnar nerve. Among these are scar sensitivity, infection, and complex regional pain syndrome.6 These complications are due to the nature of the surgical technique itself; compared with a simple in situ decompression, ulnar nerve transposition requires a larger incision, more extensive dissection, greater manipulation of the nerve, and removal of the surrounding vasculature. Another common complication of this procedure is an injury to the posterior branch of the medial antebrachial cutaneous nerve, which can result in a painful neuroma, hyperesthesia, hyperalgesia around the medial elbow, and painful scarring.7
The best surgical technique for cubital tunnel syndrome is still under debate. Therefore, the choice of surgical procedure is largely up to surgeon preference. Simple decompression of the ulnar nerve is one of the more common and simple surgical approaches to cubital tunnel syndrome, and it can be done both openly or endoscopically. Medial epicondylectomy is a less common technique but is indicated when structural abnormalities of anatomy are evident.
Anterior transposition of the ulnar nerve is another common approach to treating cubital tunnel syndrome. Although the choice of procedure is largely up to surgeon preference, there is a general consensus amongst surgeons that anterior transposition is indicated when the patient shows subluxation of the nerve upon examination. Studies that have compared ulnar nerve transposition with in situ decompression have shown no statistical difference with regards to clinical outcomes. However, it should be noted that ulnar nerve transposition is associated with a higher number of complications due to the nature and extent of its dissection.
There are three types of ulnar nerve transposition: subcutaneous, intramuscular, and submuscular. Subcutaneous transposition was first introduced by Benjamin Curtis in 1898 and is considered one of the most common approaches to cubital tunnel syndrome.8 It is generally advised to do a subcutaneous transposition over the other two approaches whenever possible. However, if there are cases with excessive preoperative nerve instability or nerve irritability or sensitivity, an intramuscular or submuscular transposition may be the preferred method. Studies have shown similar clinical outcomes between submuscular and anterior transpositions. However, one advantage of the submuscular transposition is that the muscle offers an additional layer of protection over the ulnar nerve. This can be particularly useful for patients who have relatively little subcutaneous tissue.
Nothing to disclose.
The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.
- Yahya A, Malarkey AR, Eschbaugh RL, Bamberger HB. Trends in the Surgical Treatment for Cubital Tunnel Syndrome: A Survey of Members of the American Society for Surgery of the Hand. Hand (N Y). 2018;13(5):516-521. https://doi.org/10.1177/1558944717725377
- An TW, Evanoff BA, Boyer MI, Osei DA. The Prevalence of Cubital Tunnel Syndrome: A Cross-Sectional Study in a U.S. Metropolitan Cohort. J Bone Joint Surg Am. 2017;99(5):408-416. https://doi.org/10.2106/JBJS.15.01162
- Adkinson JM, Zhong L, Aliu O, Chung KC. Surgical Treatment of Cubital Tunnel Syndrome: Trends and the Influence of Patient and Surgeon Characteristics. J Hand Surg Am. 2015;40(9):1824-1831. https://doi.org/10.1016/j.jhsa.2015.05.009
- Palmer BA, Hughes TB. Cubital tunnel syndrome. J Hand Surg Am. 2010;35(1):153-163. https://doi.org/10.1016/j.jhsa.2009.11.004
- Andrews K, Rowland A, Pranjal A, Ebraheim N. Cubital tunnel syndrome: Anatomy, clinical presentation, and management. J Orthop. 2018;15(3):832-836. Published 2018 Aug 16. https://doi.org/10.1016/j.jor.2018.08.010
- Said J, Van Nest D, Foltz C, Ilyas AM. Ulnar Nerve In Situ Decompression versus Transposition for Idiopathic Cubital Tunnel Syndrome: An Updated Meta-Analysis. J Hand Microsurg. 2019;11(1):18-27. https://doi.org/10.1055/s-0038-1670928
- Kang HJ, Koh IH, Chun YM, Oh WT, Chung KH, Choi YR. Ulnar nerve stability-based surgery for cubital tunnel syndrome via a small incision: a comparison with classic anterior nerve transposition. J Orthop Surg Res. 2015;10:121. Published 2015 Aug 6. https://doi.org/10.1186/s13018-015-0267-8
- Carlton A, Khalid SI. Surgical Approaches and Their Outcomes in the Treatment of Cubital Tunnel Syndrome. Front Surg. 2018;5:48. Published 2018 Jul 26.https://doi.org/10.3389/fsurg.2018.00048
Cite this article
Phun J, Ilyas AM. Subcutaneous ulnar nerve transposition. J Med Insight. 2021;2021(296). doi:10.24296/jomi/296.
Table of Contents
- Identify Ulnar Nerve and Examine Movement
- Start Dissection Posterior to the Medial Epicondyle
- Mobilize Nerve Circumferentially
- Mobilize Nerve Distally and then Proximally
- Transpose Ulnar Nerve Anteriorly and Complete Dissection Posteriorly
- Release First Branch to the FCU if Necessary
- Complete Dissection Distally Between the Two Heads of the FCU
- Mark for Submuscular Transposition with Z-Lengthening
- Raise Posterior Limb to Form Fascial Sling
- Close Fascial Sling to Anterior Skin Flap Subcutaneous Tissue to Secure Ulnar Nerve
For an ulnar nerve transposition, the arm is prepped and draped in standard fashion; however, I typically employ a sterile tourniquet in case I need to take the dissection more proximally. I also typically use general or regional anesthesia while with just cubital tunnel releases I can often perform those with just a local anesthesia in a wide-awake hand-surgery fashion. The incision is marked out first beginning by identifying the medial epicondyle. The incision is then taken approximately 6 cm distally and 8 cm proximally with the incision centered over, or behind, the medial epicondyle. I typically place the incision straight with the arm in full extension and then check the position upon flexion. Once marked out, I'll inject the incision with Marcaine with epinephrine for postoperative pain relief and to minimize bleeding.
Once the incision has been injected, and the limb exsanguinated, and the tourniquet inflated the incision is placed.
Blunt dissection is then performed down to the level of the forearm fascia and the level of the ulnar nerve and cubital tunnel. The priority is to identify potential branches of the medial antebrachial cutaneous nerve that may be crossing the surgical field. Most classically the nerve travels just anterior and distal to the medial epicondyle. Typically proximal and posterior to the medial epicondyle should be free of the nerve; however, diligence still must be paid to confirm that the nerve is not crossing. Injury to this nerve is common with this approach. As I take my dissection deeper and more proximally, I liberally cauterize crossing veins as this area is rich with crossing vessels and prone to hematoma formation and bruising postoperatively.
Once down to the forearm fascia, the anterior flap is elevated until the medial antebrachial cutaneous nerve is identified so that it can be protected throughout the case as shown here. This also allows elevation and exposure of the flexor pronator mass origin.
Once fully exposed, the dissection of the ulnar nerve can be started. It's helpful to identify the ulnar nerve sitting behind the medial epicondyle and exam it prior to transposition to see how it looks and how it moves. In this patient, the ulnar nerve subluxes upon elbow flexion and extension. This was evident preoperatively as well and was the primary indication for performing an ulnar nerve transposition versus a in situ cubital tunnel release.
Next, dissection of the ulnar nerve is initiated. My advice is to begin this dissection posterior to the medial epicondyle where the nerve is easy to identify and relatively lax. The fascia is opened, and the nerve is exposed. Note the use of dissecting parallel to the nerve whenever possible to help mobilize it from the surrounding tissue, I minimize damage or injury to the nerve. The nerve itself is never directly handled at any point.
Next, once adequately exposed proximally and the nerve is then mobilized circumferentially, and then with the help of a hemostat, a Penrose drain is placed behind it. It's important to try to keep the veins, or venae comitantes, that follows the ulnar nerve with it to maintain its perfusion and minimize disvascularization of the nerve.
Next, the nerve is carefully mobilized by releasing its fascia distally and then proximally. Care is taken not to injure the nerve as well as to maintain its vascularity. Again, branches of the medial antebrachial cutaneous nerve need to be protected whenever encountered. Structures requiring release beyond Osborne's ligament in the cubital tunnel includes the fascia overlying the flexor pronator mass as well as the deep investing fascia between the 2 heads of FCU. More proximally, the arcade needs to be released at least 6 to 8 cm proximally.
With the nerve circumferentially mobilized, it can be carefully transposed anteriorly. During this process, multiple vessels may be identified posteriorly tethering the nerve, which can be cauterized.
In addition, often the first branch to the FCU tethers the nerve as well. If necessary, this can be carefully isolated and cauterized and sacrificed in order to have a tension-free transposition as demonstrated here.
As the nerve is further mobilized distally, in order to facilitate anterior transposition, deeper dissection will find the deep investing fascia enveloping the nerve between the 2 heads of FCU. This close-up view here demonstrates a deep investing fascia that will often tether the nerve distally, as the nerve is being transposed anteriorly. This also requires release in order to achieve a tension-free anterior transposition as demonstrated here.
Next before formally transposing the nerve anteriorly, one last structure needs to be taken down, and that is the intermuscular septum. It should be first carefully identified inserting into the medial epicondyle. Deep to it are vessels that need to be identified, and protected, and/or cauterized. My preference is to mobilize the intermuscular septum by cauterizing it at its insertion at the medial epicondyle while also simultaneously protecting the nerve during this process. Release of the distal end of the intermuscular septum is confirmed by both direct visualization as well as feel to make sure no aspect of the septum will cause any undo tension on the nerve upon transposition. The nerve is now ready to be formally anteriorly transposed.
Prior to proceeding with the transposition, and irrespective of which transposition I will be performing, I first close the cubital tunnel. I do this by closing the fascia between the flexor pronator mass origin and the triceps. I do this in order to prevent any unwanted subluxation, or redislocation, of the ulnar nerve back into the cubital tunnel. This is particularly important when performing a subcutaneous transposition. There are a number of transposition techniques available including: subcutaneous, intramuscular, or submuscular. My advice is to perform a subcutaneous transposition whenever possible. I reserve an intramuscular or a submuscular transposition in revision cases or in cases with excessive preoperative nerve instability, or nerve irritability or sensitivity.
In all cases, whether I'm performing a subcutaneous transposition, as in this case, or a submuscular, I mark out the limbs of a possible submuscular transposition with a Z-lengthening, as shown here. This allows me to be prepared to abort to a submuscular transposition if I find that the subcutaneous transposition is under too much tension. This often happens in larger patients with large flexor pronator mass origins.
Regardless, the limb for a subcutaneous transposition that I raise is only the posterior limb, as demonstrated here. That limb is carefully elevated while making sure to protect the nerve at all times. Here you can see the proximal limb mobilized to serve as a fascial sling to keep the ulnar nerve in position anteriorly.
Next, using a mattress suture technique, the fascial sling is then repaired to the anterior skin flap subcutaneous tissue and/or fascia to keep the ulnar nerve in an anteriorly subcutaneous transposed position. It is critical to confirm that the fascial sling is adequately secure to the anterior skin flap; however, not so secure and/or not too tight as to cause secondary compression upon the ulnar nerve. This is best confirmed by direct visualization as well as by ranging the elbow to make sure that the nerve can glide smoothly without any undo tension or constriction.
As shown here, the elbow is taken through a range of motion to confirm that the sling is secure and to make sure that there's no tension on the nerve at any point, and that the nerve can glide smoothly in its anteriorly transposed position.
Once satisfied with the transposition, the wound is then copiously washed and dried. The wound is then closed in a layered fashion with no deep sutures. The first layer is 3-0 Vicryl in the subcutaneous tissue, followed by a 4-0 Monocryl in the skin at the subcuticular level, and then a glue on the skin surface. Once the wound is closed, a soft dressing is applied. No splint is used. A sling is given for protection and comfort to be used as needed. The patient is allowed to range the arm immediately. The dressing can be removed within 2 days. Activities of daily living can be resumed immediately. I recommend avoiding strenuous activity with the arm for at least 2 to 6 weeks postoperatively until the wound fully heals. Thank you.