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Techniques in Hand & Upper Extremity Surgery:
doi: 10.1097/BTH.0000000000000030
Techniques

Endoscopic Ulnar Nerve Release and Transposition

Morse, Levi P. BMBS (Hons), BPhty*; McGuire, Duncan T. MBCHB, FC Ortho, MMed; Bain, Gregory I. MBBS, FRACS, FA (Ortho) A, PhD

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*Department of Orthopaedics and Trauma, Modbury Hospital

Department of Orthopaedics and Trauma, Modbury Hospital, Royal Adelaide Hospital

Department of Orthopaedics and Trauma, Discipline of Anatomy and Pathology, Modbury Hospital, Royal Adelaide Hospital, University of Adelaide, North Adelaide, SA

Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website, www.techhandsurg.com.

Conflicts of Interest and Source of Funding: The authors report no conflicts of interest and no source of funding.

Address correspondence and reprint requests to Gregory I. Bain, MBBS, FRACS, FA (Ortho) A, PhD, Department of Orthopaedics and Trauma, Discipline of Anatomy and Pathology, Modbury Hospital, Royal Adelaide Hospital, University of Adelaide, 196 Melbourne Street, North Adelaide, SA 5006. E-mail: greg@gregbain.com.au.

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Abstract

The most common site of ulnar nerve compression is within the cubital tunnel. Surgery has historically involved an open cubital tunnel release with or without transposition of the nerve. A comparative study has demonstrated that endoscopic decompression is as effective as open decompression and has the advantages of being less invasive, utilizing a smaller incision, producing less local symptoms, causing less vascular insult to the nerve, and resulting in faster recovery for the patient. Ulnar nerve transposition is indicated with symptomatic ulnar nerve instability or if the ulnar nerve is located in a “hostile bed” (eg, osteophytes, scarring, ganglions, etc.). Transposition has previously been performed as an open procedure. The authors describe a technique of endoscopic ulnar nerve release and transposition. Extra portals are used to allow retractors to be inserted, the medial intermuscular septum to be excised, cautery to be used, and a tape to control the position of the nerve. In our experience this minimally invasive technique provides good early outcomes. This report details the indications, contraindications, surgical technique, and rehabilitation of the endoscopic ulnar nerve release and transposition.

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HISTORICAL PERSPECTIVE

Ulnar nerve entrapment at the level of the elbow is the second most common entrapment neuropathy in the upper limb behind carpal tunnel syndrome.1,2 In 1958, Feindel and Stratford coined the term cubital tunnel syndrome to describe a compression neuropathy of the ulnar nerve around the elbow with no antecedent trauma. The common sites of ulnar nerve compression are the arcade of Struthers, the medial intermuscular septum (MIMS), the cubital tunnel (most common), the flexor carpi ulnaris (FCU) fascia, and the flexor-pronator aponeurosis. These potential sites of compression extend from an average of 8 cm proximal and 5 cm distal to the medial epicondyle.2

The areas of controversy have been open versus endoscopic cubital tunnel release; and simple release versus transposition of the ulnar nerve.3–7 Several endoscopic techniques for ulnar nerve release have been described. These include techniques by Hoffman (Storz), Cobb (Integra), Tsai (glass tubes), and Bain (Agee).2,8–10

The Hoffman and Siemionow9 technique utilizes a set of instruments originally developed for endoscopic facelift surgery. A tunnelling forceps is used to develop a subcutaneous endoscopic space, into which a hooded endoscope is introduced. The hood acts as a tent post to maintain the working endoscopic space, into which scissors and other instruments can be introduced. Cobb technique utilizes the Integra EndoRelease system that has a cannula specifically designed for cubital tunnel release. The ulnar nerve is protected under this cannula while the roof of the cubital tunnel is released.8 Tsai et al10 utilized glass tubes to house an endoscope and guide a meniscus knife. The senior author has published the technique utilizing the Agee Micro-Aire endoscopic carpal tunnel device, which has a pistol grip hand-piece with a trigger that activates a retractable cutting blade.2

An endoscopic decompression has been shown to be as effective as the open decompression. However, it has the advantages of minimally invasive surgery that includes utilizing a smaller incision, causing less vascular insult to the nerve and resulting in faster patient recovery.1,7 A prospective study comparing the outcomes of the 2 techniques reported better patient satisfaction with the endoscopic technique and a lower complication rate, including elbow pain, scar tenderness, and medial elbow paraesthesia.1

The options for the treatment of cubital tunnel syndrome include either in situ ulnar nerve release and, when indicated, transposition. As discussed, ulnar nerve release can be performed either open or endoscopically. Traditionally ulnar nerve transposition has been performed by an open technique; however, we propose that an endoscopic technique may be utilized.

There are limited publications detailing endoscopic ulnar nerve transposition. Konishiike et al11 reported on a mini-open approach with endoscopic-assistance using glass tubes. Seventeen of the 20 patients had a good or excellent outcome, and all ulnar nerves remained anteriorly transposed. The use of glass tubes has fallen out of favor after reports of breaking in situ. Another small series has demonstrated favorable outcomes from an endoscopic-assisted release and mini-open transposition under carbon dioxide insufflation.12 However, carbon dioxide insufflation equipment is required. This paper describes a truly endoscopic procedure for cubital tunnel release and transposition.

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INDICATIONS/CONTRAINDICATIONS

Typically patients with cubital tunnel syndrome will present with numbness or paraesthesia in the hand, along with a burning pain around the medial epicondyle. Symptoms may be worse at night. As the disease progresses, the patient may develop weakness or clumsiness of the hand. Patients with instability of the ulnar nerve may report a snapping sensation over the medial side of the elbow, with or without the typical sensory or motor changes. Clinical examination may elicit reduced sensation in the ulnar nerve distribution and atrophy of the first dorsal interosseous muscle. If significant ulnar nerve instability is present, ranging the elbow while palpating the ulnar nerve over the cubital tunnel will demonstrate subluxation or dislocation of the nerve. Other clinical tests that can help with the diagnosis include Tinel sign over the ulnar nerve in the cubital tunnel, Froment sign, and Wartenberg sign.

Plain radiographs of the elbow can define the bony architecture and may help identify masses, erosions, arthritis, and previous trauma. Electrodiagnostic studies can be useful in detailing the severity of the compression and confirming the level of the compromise. Dynamic sonography is useful to document the presence of ulnar nerve instability. It is also the modality of choice to differentiate between snapping due to ulnar nerve dislocation versus the “snapping triceps syndrome,” in which the medial head of the triceps snaps over the medial epicondyle.

Nonoperative management for cubital tunnel syndrome includes activity modification and splinting.5 Limiting prolonged elbow flexion through sleep modification and splints can be effective. Rigid splints to prevent elbow flexion are more effective, but poorly tolerated by patients. For milder cases, splints are usually only worn at night.

The indication for ulnar nerve decompression is cubital tunnel syndrome that has failed nonoperative treatment. A trial of conservative management for several months is necessary before determining its success. However, if patients have progressive clinical findings of atrophy or reduced sensory discrimination and positive electrodiagnostic studies, conservative treatment is considered a failure. Our preference is to perform an endoscopic decompression.

Indications for transposition of the ulnar nerve in addition to decompression include subluxation or dislocation of the nerve, and any condition where the bed of the ulnar nerve behind the medial epicondyle is considered “hostile,” such as the presence of osteophytes, multiple ganglions, excessive scarring, or internal fixation. An unstable nerve can be identified on clinical examination. In contentious cases, dynamic ultrasound may be useful. Patients in whom a previous release has failed should also be considered for a transposition. At present we utilize the endoscopic ulnar nerve transposition for those patients in which transposition of the nerve is indicated.

Contraindications to the use of an endoscopic ulnar nerve release and/or transposition versus an open procedure are usually the complicated cases. This would include revision surgery, masses or space-occupying lesions; severe, long-standing elbow contractures requiring release; and prior surgery or trauma with a scarred and adherent nerve. A surgeon’s inexperience with arthroscopy/endoscopy should be considered a relative contraindication for endoscopic release. In these circumstances it is safer and easier to perform the surgery as an open procedure.

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SURGICAL TECHNIQUE—ENDOSCOPIC CUBITAL TUNNEL RELEASE

Set Up

Under general anesthesia with a pneumatic tourniquet, the patient is positioned supine with the operative arm in 90 degrees of shoulder abduction on a standard hand table. The upper extremity is draped to allow full mobility of the arm, and the surgeon flexes the elbow and externally rotates the shoulder to visualize the cubital tunnel area. A bump is placed under the elbow to elevate the arm (Fig. 1). No irrigation is required as this is a dry endoscopic technique. The Storz instrumentation is used for the ulnar nerve release and subsequent transposition (Fig. 2). The method of endoscopic ulnar nerve release we perform is similar to that reported by Hoffman and Siemionow,9 however, the ulnar nerve transposition is an extension of his work.

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Endoscopic Exposure

A 3 cm longitudinal incision is made between the medial epicondyle and olecranon (Fig. 1). Blunt dissection is performed to the level of the cubital retinaculum, the fibers of which run perpendicular to those of the aponeurosis of FCU. Tunnelling forceps are introduced to create and expand an endoscopic working space between the forearm fascia and the subcutaneous tissue for approximately 10 cm distally and proximally (Fig. 3). The hooded endoscope can also be used to elevate the subcutaneous tissues and acts as a tent pole to maintain the endoscopic working space (Fig. 4). Once the subcutaneous working space has been created, the cubital retinaculum directly over the palpable ulnar nerve is incised, to expose the ulnar nerve.

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Endoscopic Release

The hooded endoscope is advanced into the endoscopic space and the forearm fascia overlying the FCU muscle divided with Metzenbaum scissors for approximately 10 cm (Fig. 5). The ulnar nerve is identified and the soft tissues superficial to it are released, including the fibrous raphe between the 2 heads of the FCU, the deep fibrous layer of the FCU, and any other fibrous bands that constrict the nerve (Fig. 6). All of the motor branches are identified and protected (see Video, Supplemental Digital Content 1, http://links.lww.com/BTH/A39 that demonstrates the endoscopic technique for distal ulnar nerve release). The hooded endoscope is introduced proximally in the same manner and the ulnar nerve released (Fig. 7).

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Surgical Technique—Endoscopic Transposition

The transposition is performed if the nerve is unstable or if there is a hostile bed (see Video, Supplemental Digital Content 2, http://links.lww.com/BTH/A40 that demonstrates a subluxating ulnar nerve). An anterior subcutaneous pocket has been created with the tunnelling forceps anterior to the medial epicondyle. However, the subcutaneous tissue anterior to the MIMS has adherent subcutaneous fascia that requires controlled dissection and perforator vessels that require cauterization.

The MIMS is located just anterior to the ulnar verve, and is a common cause of failure of open ulnar nerve transposition, as its sharp edge can impinge on the nerve. We have utilized an extra proximal portal to allow a Langenbeck retractor to be introduced to protect the ulnar nerve posteriorly and allow better visualization of the MIMS (Fig. 8). The MIMS is isolated by reflecting the adjacent soft tissues with blunt dissection. An artery clip is introduced through the anterior portal and attached to the distal edge of the MIMS to allow it to be retracted, and its base is incised so that it can be removed (Fig. 9 and Video, Supplemental Digital Content 3, http://links.lww.com/BTH/A41 that demonstrates the use of an artery clip for MIMS excision). There are sizable vessels close by that need to be protected.

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We have used a nylon tape that is passed around the released ulnar nerve, and then fed through an extra anterior portal (Fig. 10). With light traction on the tape, the ulnar nerve will be withdrawn from its bed, allowing magnified endoscopic visualization of the underlying loose areolar tissue that connects the ulnar nerve to its bed and the adjacent motor branches and vessels. The loose areolar is divided with Metzenbaum scissors mobilizing the ulnar nerve, aiming to preserve the vessels and prevent ischemia of the nerve (see Video, Supplemental Digital Content 4, http://links.lww.com/BTH/A42). There are often vessels at the level of the medial epicondyle that require cauterization. The loose areolar tissue that tethers the motor branches to the ulnar nerve and to the FCU can also be released, to provide greater ulnar nerve mobilization (see Video, Supplemental Digital Content 5, http://links.lww.com/BTH/A43).

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Once the ulnar nerve has been mobilized it is transposed anterior to the medial epicondyle. The surgeon may choose to repair the incised deep fascia over the proximal forearm to prevent muscular herniation. This can be performed endoscopically with barbed sutures, which do not require ligation (see Video, Supplemental Digital Content 6, http://links.lww.com/BTH/A44 that demonstrates the use of endoscopic suturing in a cadaver model). Suturing the entire length of released fascia must not be performed, as it will pinch the nerve.

The nerve must be assessed proximally and distally to ensure that there is no tethering, especially as it traverses the areas of the MIMS and the FCU (Fig. 11 and Video, Supplemental Digital Content 7, http://links.lww.com/BTH/A45 that demonstrates the transposed ulnar nerve). It is important to prevent the nerve reducing back behind the medial epicondyle. We rasp the medial epicondyle to encourage it to heal to the subcutaneous tissue. Sutures are placed from the subcutaneous fat to the medial epicondyle, whereas light traction on the nylon tape keeps the nerve transposed (Fig. 12). Before ligating the sutures we deflate the tourniquet, cauterize any bleeding vessels under endoscopic vision, infiltrate the soft tissues with local anesthetic, and irrigate the cavity with normal saline. The portals are sutured. A dressing is applied and the arm is placed into a sling with the elbow at 90 degrees of flexion.

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Complications

Complications can relate to the ulnar nerve or to the local elbow tissues. Ulnar nerve pain and paraesthesia can be due to ulnar nerve entrapment, ischemia, or irritation at the level of the MIMS or between the FCU heads. Persistent ulnar nerve instability could occur if the nerve passes behind the medial epicondyle. Cutaneous nerve injuries as part of the surgical exposure can produce forearm paraesthesia.

The most common reported complication associated with endoscopic ulnar nerve release is hematoma formation. As such, the authors recommend deflating the tourniquet to obtain hemostasis before closure. Wound dehiscence has also been reported, more commonly associated with the use of Steri-Strips (3M Nexcare, MN) for closure.8

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Rehabilitation

The sling is maintained for 10 days after transposition to ensure the subcutaneous tissue heals to the medial epicondyle. During this period the patient is encouraged to begin gentle active ROM of the elbow. After 10 days full mobilization is allowed. Return to light work is allowed from 10 days, however, return to moderate or heavy manual labor is delayed for 6 or 12 weeks, respectively.

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RESULTS

We have performed this operation on 11 cases over 3 years. Patients were all males with an average age of 52 years (range, 18 to 78 y). There have been no major complications, including no reoperations, infections, nerve injuries, or recurrent ulnar nerve instability. It has been our experience that this operation improves the snapping in those patients with an unstable nerve, and removes the aching pain over the medial elbow and forearm. However, the patients with significant preoperative nerve involvement (eg, McGowen grade 3 ulnar nerve involvement), often have persistent paraesthesia and muscle wasting in the hand, despite their surgery.

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REFERENCES

1. Watts AC, Bain GI.Patient-rated outcomes of ulnar nerve decompression: a comparison of endoscopic and open in situ decompression.J Hand Surg Am.2009;34:1492–1498.

2. Bain GI, Bajhau A.Endoscopic release of the ulnar nerve at the elbow using the Agee device: a cadaveric study.Arthroscopy.2005;21:691–695.

3. Zlowodzki M, Chan S, Bhandari M, et al..Anterior transposition compared with simple decompression for treatment of cubital tunnel syndrome. A meta-analysis of randomized, controlled trials.J Bone Joint Surg Am.2007;89:2591–2598.

4. Macadam SA, Gandhi R, Bezuhly M, et al..Simple decompression versus anterior subcutaneous and submuscular transposition of the ulnar nerve for cubital tunnel syndrome: a meta-analysis.J Hand Surg Am.2008;33:1314, e1–12.

5. Gellman H.Compression of the ulnar nerve at the elbow: cubital tunnel syndrome.Instr Course Lect.2008;57:187–197.

6. Ahcan U, Zorman P.Endoscopic decompression of the ulnar nerve at the elbow.J Hand Surg Am.2007;32:1171–1176.

7. Cobb TK, Tyler J, Sterbank P, et al..Efficiency of endoscopic cubital tunnel release.Hand.2008;3:191.

8. Cobb TK.Endoscopic cubital tunnel release.J Hand Surg Am.2010;35:1690–1697.

9. Hoffmann R, Siemionow M.The endoscopic management of cubital tunnel syndrome.J Hand Surg Br.2006;31:23–29.

10. Tsai TM, Bonczar M, Tsuruta T, et al..A new operative technique: cubital tunnel decompression with endoscopic assistance.Hand Clin.1995;11:71–80.

11. Konishiike T, Nishida K, Ozawa M, et al..Anterior transposition of the ulnar nerve with endoscopic assistance.J Hand Surg Eur.2011;36:126–129.

12. Jiang S, Xu W, Shen Y, et al..Endoscopy-assisted cubital tunnel release under carbon dioxide insufflation and anterior transposition.Ann Plast Surg.2012;68:62–66.

Keywords:

ulnar nerve; endoscopic; transposition; minimally invasive; endoscopy

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