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Treatment Options for Cubital Tunnel Syndrome
Treatment Options for Cubital Tunnel Syndrome Brian J. Kelly, MD,* and Thomas B. Hughes, MD† Compression of the ulnar nerve can occur at multiple sites at the level of the elbow, and it is the second most common compressive neuropathy after carpal tunnel syndrome. At this time, the evidence does not suggest that there is a superior procedure for treatment of ulnar nerve decompression. It is largely dependent on surgeon preference and comfort level. In situ decompression is the simplest procedure, with the least disruption of the normal anatomy and similar results to the more extensive anterior transposition or medial epicondylectomy. The more recent use of endoscopic techniques may further minimize the postoperative recovery time and duration of pain symptoms beyond what is seen with in situ decompression. These procedures are commonly performed and well described in the literature, and the techniques for each procedure are summarized here. The authors suggest a surgical algorithm of in situ decompression as the primary option for ulnar nerve decompression with anterior transposition may best be reserved for revision cases refractory to in situ decompression or cases in which the ulnar nerve is found to subluxate anterior to the medial epicondyle when observed through a full range of motion after in situ decompression. Oper Tech Orthop 23:232-242 C 2013 Elsevier Inc. All rights reserved. KEYWORDS cubital tunnel, ulnar nerve compression, neurolysis
Background and Anatomical Considerations
C
ompression of the ulnar nerve has many causes and can occur at multiple anatomical sites (Fig. 1). The most common site of ulnar nerve compression is at the level of the elbow, and it is the second most common compressive neuropathy after carpal tunnel syndrome.1-4 The ulnar nerve originates from the medial cord of the brachial plexus and finds its origin from the C8 and T1 nerve roots. The course of the ulnar nerve is through the medial arm, posteromedial to the brachial artery, between the medial head of the triceps and the brachialis muscles. It courses through the anterior compartment proximally, pierces the medial intermuscular septum in the midbrachium, and crosses from the anterior compartment to the posterior compartment.3 The
*Department of Orthopaedic Surgery, Allegheny General Hospital, Pittsburgh, PA. †University of Pittsburgh School of Medicine, Orthopaedic Specialists, Pittsburgh, PA. Address reprint requests to Thomas B. Hughes, MD, University of Pittsburgh School of Medicine, Orthopaedic Specialists, UPMC, 9104 Babcock Blvd, Suite 5113, Pittsburgh, PA 15237. E-mail: [email protected], [email protected]
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1048-6666/13/$-see front matter & 2013 Elsevier Inc. All rights reserved. doi:http://dx.doi.org/10.1053/j.oto.2013.08.008
arcade of Struthers is found approximately 8 cm proximal to the medial epicondyle and consists of a band of fascia connecting the medial intermuscular septum to the medial head of the triceps. It is made up of the medial intermuscular septum, the internal brachial ligament, and the deep fascia of the medial head of the triceps5; the anatomy is somewhat controversial, but it represents a potential site of compression.3,5 Moving distally, the next potential site of compression is the medial epicondyle. Compression here can be resultant from medial epicondyle fracture callus or malunion, heterotopic ossification, osteophytes from osteoarthritis or rheumatoid arthritis, or cubitus varus or valgus deformity.3 The next potential site of compression is the cubital tunnel. This is defined by the arcuate ligament of Osbourne medially, the medial collateral ligament of the elbow laterally, the medial epicondyle anteriorly, and the olecranon and triceps tendon posteriorly.3,6 The arcuate ligament of Osborne is a thickened band between the humeral and ulnar heads of the flexor carpi ulnaris muscle. The final potential site of nerve compression in the elbow region is the deep flexor-pronator aponeurosis, which overlies the flexor carpi ulnaris muscle as the ulnar nerve passes from the superficial to the deep region between the humeral and ulnar heads of the muscle.3 The extrinsic blood supply to the ulnar nerve is also important in understanding the surgical techniques for
Treatment options for cubital tunnel syndrome
233 Ulnar nerve compression in the elbow region must be differentiated from ulnar nerve compression in the hand at the Guyon canal. Sensation to the dorsoulnar aspect of the hand would also be intact, but there may be hypesthesias of the palmar aspect of the hand.8 In advanced disease, there is more significant clawing of the small and ring fingers with compression at the hand, as the flexor digitorum profundus muscle is not affected by nerve compression at this site.8 Provocative clinical testing can be conducted to further help differentiate these potential sites of nerve compression. Compression of the ulnar nerve at the elbow is far more common than in the palm.
Figure 1 The course of the ulnar nerve around the elbow and the common sites of compression: the arcade of Struthers, the medial intermuscular septum, the fascia of the triceps as it attaches to the medial intermuscular septum, the cubital tunnel proper (the ligament of Osbourne), the flexor-pronator aponeurosis, and the flexor carpi ulnaris muscle.
decompression. There are 2 major vascular pedicles that supply the ulnar nerve in the elbow region (Fig. 2): the superior ulnar collateral artery (SUCA) proximally and the posterior ulnar recurrent artery (PURA) distally. The inferior ulnar collateral artery lies between both of them; it is variably present, representing a minor contribution to the extrinsic blood supply.7 The SUCA and inferior ulnar collateral artery are branches of the brachial artery, while the PURA is a branch of the ulnar artery.
Clinical Presentation Patients with ulnar nerve compression generally present with a combination of elbow pain and sensory and motor symptoms.8 Symptoms are usually worse with flexion. Numbness and paresthesias are usually the predominant early features, with pain being less common initially.3 Sensory complaints usually begin with intermittent paresthesias of the small and ring fingers. These symptoms are exacerbated by elbow flexion or pressure on the medial elbow, and they may awaken the patient from sleep.8 Symptoms of sensory fiber compression can progress to actual sensory loss, which is noted over the small finger, ulnar ring finger, the ulnar palm, and the dorsoulnar aspect of the hand.3,8 Symptoms of motor fiber compression are also generally progressive. Initially, patients complain of loss of fine motor control (eg, inability to fasten buttons or lift a coin from a flat surface).3,8 The symptoms may begin with intrinsic muscle weakness and progress to weakness, atrophy, or paralysis of both the intrinsic and extrinsic muscles innervated by the ulnar nerve. Sensory symptoms and intrinsic muscle weakness are likely involved before extrinsic muscle weakness because their fibers are more peripheral within the structure of the ulnar nerve.8 When there is weakness or paralysis of the intrinsic muscles but intact function of the flexor digitorum profundus muscle, evidence of clawing can be observed in the small and ring fingers. If the flexor digitorum profundus muscle is also affected, clawing is usually absent.3,8
Conservative Treatment Before surgical intervention, conservative treatment options should be attempted. Patients should be instructed to avoid prolonged elbow flexion or direct compression of the elbow as in resting it on a table or car door.3,8 At night, using an elbow splint with the elbow maintained in a semiflexed position of approximately 451-601 of flexion may be helpful.8 Physical therapy may also be attempted with nerve mobilization techniques.3,8 These nonoperative treatment options should be attempted for 4-6 weeks before any surgical planning.8 In the event that these conservative measures fail and the symptoms of ulnar nerve compression persist, proceeding with surgical planning is indicated. When patients have constant symptoms of ulnar nerve compression, or when muscle atrophy is noted clinically, surgical intervention without a full trial of nonoperative treatment is indicated.3 Constant numbness is frequently not appreciated by the patient, as they may only note the exacerbations of paresthesias. However, simple sensory testing in the office can frequently reveal that even when patients think their hand is functioning “normally,” they do have subjectively decreased ulnar sensation.
Surgical Considerations As stated previously, there are 5 major sites of ulnar nerve compression in the elbow region (Fig. 1): the medial intermuscular septum, the arcade of Struthers, the medial
Figure 2 The 2 major vascular pedicles that supply the ulnar nerve are the superior ulnar collateral artery (SUCA) proximally and the posterior ulnar recurrent artery (PURA) distally. The inferior ulnar collateral artery (IUCA) has a minor contribution and is variably present. The SUCA and the IUCA are branches of the brachial artery, while the PURA is a branch of the ulnar artery.
234 epicondyle, the cubital tunnel, and the deep flexor-pronator aponeurosis. The most common site of compression is at the cubital tunnel, but all sites of potential compression should be evaluated and released during the surgurical procedure. The surgical techniques for ulnar nerve decompression fall into 3 major categories: in situ decompression (open or endoscopic), decompression with nerve transposition, and medial epicondylectomy.
Operative Setup The patient is positioned supine on the operating table with the operative extremity abducted onto a hand table. General anesthesia, regional anesthesia, and intravenous sedation with local anesthesia are the options for these procedures, the latter likely being insufficient for epicondylectomy or deep transpositions. An upper arm pneumatic tourniquet is utilized before positioning the extremity. With the operative extremity abducted, the shoulder is externally rotated and a bump is placed beneath the lateral aspect of the elbow to help with shoulder external rotation and mild valgus stress on the elbow, facilitating the approach to the ulnar nerve (Fig. 3). The patient is sterilely prepared and draped according to the preference of the operating surgeon. The primary surgeon sits medial to the abducted extremity in the axilla of the patient, while the assisting surgeon sits lateral to the abducted extremity to assist with retraction and exposure.
In Situ Decompression An incision is made posterior to the medial epicondyle, along the course of the ulnar nerve, through the dermis only. The length of the incision depends on the surgeon’s experience and preference. While the nerve must be decompressed over a region of approximately 12-15 cm, the skin incision required for this may only be 2-3 cm (Fig. 4A). However, when initially performing the procedure, an
Figure 3 The operative extremity abducted with the shoulder externally rotated. A bump of towels is placed beneath the lateral aspect of the elbow to help with shoulder external rotation and to provide a mild valgus stress. (Color version of figure is available online.)
B.J. Kelly and T.B. Hughes incision of 6-10 cm centered over the ulnar nerve in the cubital tunnel should be used.3 With more experience, an incision of 2-3 cm can be used. Through the small incision, deep dissection is performed by using scissors to bluntly spread through the subcutaneous fat and loosen the connective tissue to the level of the deep fascia overlying the ulnar nerve (Fig. 4B). Care is taken to identify and protect any branches of the medial antebrachial cutaneous nerve (MABC). There are usually between 1 and 3 branches of this nerve within 6 cm proximally and distally from the medial epicondyle (Fig. 5).9,10 On palpation, the ulnar nerve can be found running in its bed posterior to the medial epicondyle. It is not uncommon to find the dissection has drifted posteriorly, palpating the edge of the triceps instead of the nerve. However, the nerve is always just posterior to the epicondyle, and maintaining the dissection in this region would facilitate the entire procedure. The arcuate ligament of Osbourne is carefully punctured using blunt-tipped scissors. The decompression is performed by using dissecting scissors to spread beneath the fascia, superficial to the nerve, to develop a plane; the fascia is then lifted using forceps and incised longitudinally along the course of the nerve. Typically, only the cubital tunnel proper can be visualized through this small incision. The large end of an army-navy retractor is then placed at the proximal edge of the incision (Fig. 4C). Blunt dissection is carried out with wide spreads of the tips of the scissors to lift the subcutaneous tissues from the fascia. This also lifts any branches of the MABC with the subcutaneous fat, limiting the amount of dissection around these sensory nerves, hopefully limiting postoperative MABC symptoms. There may be some fascial bands that extend superficially from the fascia to the dermis. These may require cutting with the tips of the scissors. Care must be taken here to avoid cutting a sensory nerve or any proximal veins. Coagulation of any veins should be done with bipolar cautery before cutting them. The decompression is carried out proximally to the medial intermuscular septum and arcade of Struthers. With traction and the larger end of the army-navy retractor, the dissection can be carried at least 10-12 cm proximal to the medial epicondyle (Fig. 4C). Longer-handled, tenotomytype scissors may be beneficial here as a large part of the dissection is performed under the skin. Once the proximal dissection is completed, the army-navy retractor is placed distally (Fig. 4D), and the release performed through the distal portion of the arcuate ligament of Osbourne. The superficial fascia between the 2 heads of the Flexor Carpi Ulnaris (FCU) is released, the muscle fibers are gently separated bluntly, and then the deep fascia is released to the level where the humeral and ulnar heads unite. The nerve is retained in its bed of surrounding connective tissue, and no circumferential dissection is required. This is thought to help preserve as much extrinsic blood flow to the nerve as possible.7 It also limits nerve subluxation with elbow range of motion. The elbow is then taken through a complete range of motion to ensure that the nerve does not subluxate or snap over the medial epicondyle. Frequently, the nerve moves medially with elbow flexion, riding up
Treatment options for cubital tunnel syndrome
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Figure 4 (A) A medial incision is made posterior to the medial epicondyle. The line drawn on the skin represents the course of the ulnar nerve. The incision is located directly over the cubital tunnel.(B) The subcutaneous tissues are elevated from the underlying fascia. In this image, the ulnar nerve can be visualized within the cubital tunnel (U), but it has not yet been released. The large end of the army-navy retractor is inserted to its fullest extent and the subcutaneous tissues are lifted from the fascia to this point. The nerve is released to this point proximally (PR). A small branch of the MABC is identified. The army-navy retractor is repositioned deep to these branches and they are preserved.(C) The Cubital tunnel is released revealing the underlying ulnar nerve (U). The army-navy retractor protects all the subcutaneous tissues, including any MABC branches, and is superficial to the fascia (n) that is to be released. Through this approach, the fascia can be divided proximally to the arcade of Struthers.(D) The army-navy retractor is placed distally. The tip of the retractor can be visualized under the skin, marked by the tip of the scissors. By lifting the soft tissues, the nerve can be directly visualized and released distally to the point marked DR. (U, ulnar nerve; M, medial epicondyle O-tip of olecranon, P-proximal, D-distal, DR-distal extent of release, PR-proximal extent of release, MABC-medial antebrachial cutaneous nerve, n-fascia.) (Color version of figure is available online.)
along the edge of the medial epicondyle (Fig. 6). However, if it does not subluxate, the authors prefer to leave it in situ. If it does subluxate, the authors prefer to transpose the nerve at this point (refer to the section “Anterior Transposition” given later), although some surgeons do not feel it is necessary even in these cases.11 Closure can be done according to surgeon preference, but care must be taken not to create an additional source of potential nerve compression. For this reason, only the skin is closed without closing any deeper layers. A sterile soft dressing is applied without any splint immobilization, and elbow range of motion is encouraged.
Endoscopic Decompression Endoscopic decompression applies the principles of in situ decompression but through a smaller incision than is typically
used for open decompressions. It has the additional benefit of enhanced lighting and magnification through the endoscope. The patient is positioned, prepared, and draped as for the open procedures; a tourniquet is also used. It is important to place the elbow in a semiflexed position because if there is too much flexion the endoscopic instrumentation can bind up in the canal. An incision of 1.5-4 cm is made over the cubital tunnel posterior to the medial epicondyle; patients with more subcutaneous necessitate a larger incision.12 A longer incision is also recommended if a surgeon is unfamiliar with the procedure for the first few cases. The incision is taken through skin with a scalpel. The dissection is continued using scissors to spread through the subcutaneous fat and loosen the connective tissue while care is taken to avoid the branches of the MABC.9 The initial dissection is carried out to the level of the deep fascia. Long, blunt dissecting scissors are then used to develop the potential space between the adipose tissue and deep fascia proximal and distal to the incision to facilitate the
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Figure 5 The average distance from the proximal crossing branch of the MABC to the medial epicondyle is 1.8 cm (A), and the average distance from the medial epicondyle to the distal crossing branch of the MABC is 3.1 cm (B).
endoscopic exposure (Fig. 7). The superficial dissection is performed 10-14 cm both proximal and distal to the medial epicondyle.12 After the superficial dissection is completed, the ulnar nerve is identified by palpation or direct visualization. The arcuate ligament of Osbourne overlying the nerve is incised with blunttipped scissors. The cubital tunnel must be opened sufficiently to allow insertion of the endoscopic instrumentation, approximately 2 cm usually. A blunt spatula is inserted into the potential space between the ulnar nerve and the overlying deep fascia (Fig. 8); it is used to develop this space approximately 10 cm both proximal and distal to the medial epicondyle.12 The spatula should advance this distance with minimal resistance. After removing the spatula, the endoscopic cannula with a blunt-tipped trocar is inserted into this space to nearly the same distance; the attached retractor is inserted into the potential space between the deep fascia and subcutaneous fat
Figure 6 Following release, the elbow is fully flexed. The nerve may move medially, as shown here, and ride up along the medial epicondyle. If it does not sublux, it is not transposed (refer to video). (U, ulnar nerve; M, medial epicondyle; P, proximal.) (Color version of figure is available online.)
B.J. Kelly and T.B. Hughes
Figure 7 Long, blunt dissecting scissors are used to develop the potential space between the adipose tissue and deep fascia proximal and distal to the incision to facilitate the endoscopic exposure. This is carried out to a distance of approximately 10-14 cm both proximal and distal to the medial epicondyle. (Color version of figure is available online.)
and elevated to a level sufficient for good visualization of the deep fascia.12 The endoscope is initially placed between the cannula and the retractor to ensure that there are no superficial nerves in the way. The endoscope is then inserted into the cannula and turned inferiorly to identify the ulnar nerve through the slots in the cannula along its entire course. After the nerve is clearly identified, the deep fascia is divided with the endoscopic blade passed along the superior slot of the cannula (Fig. 9). This technique is carried out distally to the level of the fibrous raphe between the humeral and ulnar heads of the FCU; it is then carried out proximally to the level of the ligament of Struthers.12 If at any point resistance is encountered, the
Figure 8 A blunt spatula is inserted into the potential space between the ulnar nerve and the overlying deep fascia to develop this space to a level of approximately 10 cm both proximal and distal to the medial epicondyle. (Color version of figure is available online.)
Treatment options for cubital tunnel syndrome
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Figure 9 The endoscope is inserted into the cannula and turned inferiorly to identify the ulnar nerve through the slots in the cannula along its entire course. After the nerve is clearly identified, the deep fascia is divided with the endoscopic blade passed along the superior slot of the cannula. This technique is carried out distally to the level of the fibrous raphe between the humeral and ulnar heads of the FCU; it is then carried out proximally to the level of the ligament of Struthers. (Color version of figure is available online.)
cannula should be removed, the spatula reinserted, and the steps followed sequentially again. Once the release is complete, the cannula is removed. The retractor and endoscope are reinserted to confirm the completeness of release. The tourniquet is released and the same direct visualization is used to confirm adequate hemostasis; bipolar electrocautery may be used if necessary. The skin is closed and dressed as for in situ decompression. Multiple variations of this technique have recently been described in the literature, but the basic principles are the same. Blunt dissection to lift the superficial tissue and MABC branches from the underlying fascia is followed by blunt dissection between the ulnar nerve and the deep fascia. Once the fascia over the nerve is dissected free, both superficial and deep, the nerve is decompressed by incising the deep fascia. A well-described alternative technique is using long-handled tenotomy scissors to release the nerve through similar endoscopic speculum instrumentation (Fig. 10).13 In yet another technique, a retractor is used to lift the superficial tissues as a glass tube is placed beneath the deep fascia overlying the ulnar nerve; a specially designed knife is then used to incise the deep fascia along the more superficial surface of the glass tube.14 The instrumentation that is used for each step varies for each manufacturer’s technique and product line, and the surgeon should become familiar with the instrumentation used by their practice or hospital.
the initial complications of elbow instability from resecting too much of the epicondyle and disrupting the musculoligamentous complex of the medial elbow. The initial incision is 9-13 cm, and it is made just anterior to the cubital tunnel. The dissection and ulnar nerve decompression are conducted as in the in situ decompression. Once the ulnar nerve is decompressed, the medial epicondyle is exposed subperiosteally. The flexor-pronator muscular origin is left intact on the periosteal sleeve. A portion of the flexor-pronator origin may be incised and reflected distally as needed as long as some cuff
Medial Epicondylectomy
Figure 10 The illuminated speculum and endoscope are inserted into the space superficial space created above the deep fascia. Longhandled tenotomy scissors are used to release the deep fascia overlying the nerve. (Color version of figure is available online.)
Medial epicondylectomy was originally described by King and Morgan in 1950,3,15-17 and it has since been refined because of
B.J. Kelly and T.B. Hughes
238 remains on the periosteal sleeve for eventual repair.16 It is important to maintain flaps of periosteum both anteriorly and posteriorly to facilitate closure (Fig. 11A). With the medial epicondyle fully exposed, an osteotome is used to score along the metaphyseal-diaphyseal junction to identify the limit of the resection. In the earlier descriptions of this procedure, the medial margin of the trochlea was used as a guide for the bony resection15,16; however, complications related to overresection and resultant elbow instability were common. It is now common practice to identify the origin of the anterior bundle of the medial collateral ligament as part of the exposure of the medial epicondyle. It is important not to disrupt this primary stabilizer of the elbow joint during the epicondylectomy.18,19 To avoid this structure, an oblique osteotomy between the coronal and sagittal planes of the epicondyle is done using a small osteotome (Fig. 11B).19 This creates a flat surface for the
nerve to glide on while preventing destabilization of the elbow. Rongeurs or rasps are used to smooth the surface of the cut bone. The elbow is then taken through a full range of motion to ensure that there are no remaining bony prominences for the nerve to catch on or snap over. The fascia and periosteum can be repaired over the remaining epicondyle using nonabsorbable suture (Fig. 11C). If a portion of the flexor-pronator mass was taken down, it is repaired to the cuff of its origin using absorbable suture. The skin is closed as in in situ decompression and a soft dressing is applied. As there was disruption of the bony architecture, the elbow is often splinted at 901 for 1-2 weeks postoperatively before allowing full elbow range of motion; this period should last no longer than 2 weeks to prevent postoperative elbow stiffness.
Figure 11 (A) Anterior and posterior flaps are elevated by subperiosteal dissection to fully expose the medial epicondyle. Electrocautery can be used to mark out the planned osteotomy. (B) In order to avoid disrupting origin of the anterior bundle of the MCL, a small osteotome is used to create an oblique osteotomy between the coronal and sagittal planes of the epicondyle. This creates a flat surface for the nerve to glide on while preventing destabilization of the elbow. (C) The fascia and periosteum is repaired over the remaining epicondyle using nonabsorbable suture. If a portion of the flexor-pronator mass was included in the exposure, it is also included in this repair.
Treatment options for cubital tunnel syndrome
Anterior Transposition An incision is made as in in situ decompression; however, it is carried to a longer distance of 3-10 cm proximally in line with the medial intramuscular septum and 3-10 cm distally in line with the FCU fascia between its 2 heads. The length of the incision depends on the surgeon’s preference, the type of transposition to be performed, and ability to obtain adequate exposure. A longer incision is required if an intramuscular or submuscular transposition is to be performed (submuscular transposition generally requires the longest incision of all the possible procedures). If a longer incision is required, it is performed at an angle of approximately 1201, with the apex posteriorly between the medial epicondyle and the olecranon.20 The exposure and decompression are performed as described in the in situ decompression section. The nerve is then mobilized with its accompanying blood vessels from proximal to distal; particular care is taken to preserve the SUCA and PURA (Fig. 2).7 Moving distally, the ligament of Osbourne is divided and, it is done at the expense of small articular branches of the nerve, if present. All motor branches to the ulnar head of the FCU are spared. To facilitate transposition, these motor branches may need to be dissected extensively into the muscle to have adequate length to transpose the ulnar nerve.21,22 If necessary, subperiosteal mobilization of the FCU muscle belly from the olecranon process can be performed. Once the nerve is adequately mobilized, it is transposed, as described in the following section, depending on the desired final location for the nerve.
Subcutaneous Transposition The medial intermuscular septum is identified and excised from the proximal extent of the decompression to the level of the medial epicondyle to prevent compression of the ulnar nerve as it crosses the edge of the septum.10 The nerve is
239 transposed anterior to the medial epicondyle to its new position. A small sling can be created approximately at the level of the medial epicondyle to prevent the nerve from returning to its original posterior position. A 1.5-cm wide and 2-cm long strip of fascia from the flexor-pronator mass is elevated, keeping it attached medially (Fig. 12A). It is sewn using absorbable suture to the undersurface of the dermis.21,23,24 Care is taken to sew it to a more posterior portion of the dermis so that the sling does not cover and compress the nerve, but rather sits posterior to the nerve, preventing subluxation of the nerve back into the cubital tunnel (Fig. 12B). The skin is closed as in in situ decompression according to surgeon preference. A sterile soft dressing is applied without any splint immobilization, and elbow range of motion is encouraged.
Intramuscular Transposition If the surgeon wishes to place the nerve within the muscle, the release and transposition are performed as described previously. The fibrous aponeurosis between the flexor digitorum superficialis muscle of the ring finger and the FCU is released, as is proximal border of the pronator teres fascia. The excision of these structures allows the nerve to be transposed anteriorly without any kinks.10,20 The nerve is moved to its anterior position, and the position of the nerve on the underlying flexor-pronator musculature is noted; the position can be marked out using a marking pen. The nerve is temporarily replaced posterior to the medial epicondyle while its new course is prepared. The flexorpronator fascia is incised along the new anterior course of the ulnar nerve, and a trough of 5-10 mm in depth is fashioned in the flexor-pronator musculature. The fibrous septa separating the individual flexor-pronator muscles are excised to ensure a soft, well-vascularized bed for the new course of the nerve.10,20 The nerve is then moved anteriorly again into the newly created bed (Fig. 13A). The forearm is
Figure 12 (A) A small sling can be created approximately at the level of the medial epicondyle to prevent the nerve from returning to its original posterior position. A 1.5 cm wide and 2 cm long strip of fascia from the flexor-pronator mass is elevated, keeping it attached medially. (B) The strip of fascia is attached with absorbable suture to the undersurface of the dermis. Care is taken to sew it to a more posterior portion of the dermis so that the sling does not cover and compress the nerve, but rather sits posterior to the nerve, preventing subluxation of the nerve back into the cubital tunnel.
B.J. Kelly and T.B. Hughes
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Figure 13 (A) The flexor-pronator fascia is incised along the new anterior course of the ulnar nerve, and a trough of 5-10 mm in depth is fashioned in the flexor-pronator musculature. The fibrous septa separating the individual flexorpronator muscles are excised to ensure a soft, well-vascularized bed for the new course of the nerve. The nerve is then moved anteriorly again into the newly created bed. (B) The forearm is placed into a fully pronated position with the elbow flexed to 901, and the flexor-pronator fascia is repaired over the nerve using absorbable suture. (Color version of figure is available online.)
placed into a fully pronated position with the elbow flexed to 901, and the flexor-pronator fascia is repaired over the nerve using absorbable suture (Fig. 13B). Fractional lengthening of the fascia is usually necessary to prevent additional compression of the nerve.20 The elbow is taken through a full range of motion to demonstrate free excursion of the nerve throughout its new course and within the intramuscular tunnel. The skin is closed according to surgeon preference, and a sterile soft dressing is applied. Early range of motion is encouraged, but strengthening is delayed for 6 weeks.
Submuscular Transposition Once the ulnar nerve is circumferentially released as described previously, the flexor-pronator mass is identified and incised 1-2 cm distal to the medial epicondyle. The incision is carried out in a step-cut fashion, which allows for fractional lengthening of the muscle after the nerve is transposed beneath it.25 Once the muscle is incised and reflected distally, the ulnar collateral ligament, median nerve, and brachial artery are identified and protected. The ulnar nerve is transposed anteriorly beneath the reflected flexor-pronator mass into a position parallel and just ulnar to the median nerve. The reflected muscle is then repaired over the transposed nerve with fractional lengthening to prevent an additional source of possible nerve compression.25 The skin is closed according to surgeon preference. A sterile soft dressing is applied without any splint immobilization, and elbow range of motion is encouraged.
Summary and Evidence The choice of which of these procedures to perform is often based on surgeon preference, but there is a large amount of
research that has been done to compare these various techniques. Many studies have been done comparing simple in situ decompression of the ulnar nerve with the more complex procedures. A meta-analysis of randomized controlled trials and observational studies also compared in situ decompression with anterior transposition (subcutaneous or submuscular).26 There was no significant difference in outcomes; however, they did note a trend toward improved clinical outcomes with anterior transposition. No significant difference in clinical outcomes was found when they performed a subanalysis of subcutaneous and submuscular transposition. Baek et al27 compared medial epicondylectomy with anterior subcutaneous transposition, and there was found to be no significant difference in subjective outcomes or objective clinical findings; both procedures had high rates of patient satisfaction and good objective results. In a recent retrospective review comparing in situ decompression, medial epicondylectomy, and anterior subcutaneous transposition, they found that all 3 treatment options had overall good outcomes.28 However, they did find that the percentage of good and excellent results for anterior transposition was significantly lower than that of in situ decompression or medial epicondylectomy. The preoperative symptoms were slightly worse in this group, though, and the power of the study does not allow definitive conclusions. A retrospective review comparing submuscular and subcutaneous anterior transposition of the ulnar nerve found no significant difference in sensory, motor, or subjective recovery between both the procedures.29 They did find that patients with symptoms that had been present for more than 6 months had a worse prognosis. Overall, it is difficult to draw firm conclusions from the existing data. Randomized controlled trials are difficult to perform in this patient population, and such a trial would likely have to retain 200 patients per treatment arm to achieve statistical power.26
Treatment options for cubital tunnel syndrome A recent prospective case-control study compared subjective patient outcomes of open and endoscopic decompression and found that they were equivalent; they also found that more complications were reported with open decompression.30 Another study comparing open and endoscopic decompression again found good subjective and objective outcomes in the long term that were not significantly different; however, they found that there was a statistically significant decrease in the duration of postoperative pain and the time to return to work with endoscopic decompression.31 As endoscopic techniques improve and the procedure becomes more widely adopted, the decreased pain and recovery time may convince more surgeons to use it as their first-line surgical option. These data suggest a surgical algorithm of in situ decompression as the primary option for ulnar nerve decompression. It necessitates the least soft tissue dissection and least potential disruption of the blood supply to the nerve. Anecdotally, since changing to in situ decompression from subcutaneous transposition, the authors have found a significantly quicker recovery with fewer complaints of MABC symptoms and chronic medial elbow pain. Anterior transposition may best be reserved for revision cases refractory to in situ decompression or cases in which the ulnar nerve is found to subluxate anterior to the medial epicondyle when observed through a full range of motion after in situ decompression. Goldfarb et al,32 in a case series of 69 extremities for which in situ decompression was carried out, found that only 5 extremities had persistent or recurrent symptoms. All 5 of these extremities experienced resolution of symptoms with subsequent anterior transposition of the nerve. This supports the use of anterior transposition as the treatment option for refractory cases. It is also the author’s primary choice in patients who have symptomatic ulnar nerve subluxation preoperatively. There are those who note that some amount of nerve subluxation can be found within a normal population, so the choice of anterior transposition because subluxation is seen intraoperatively may not be necessary.11 More evidence is needed to discern whether anterior transposition truly makes a significant clinical difference when nerve subluxation is present. Currently, the evidence does not suggest that there is a superior procedure for treatment of ulnar nerve decompression. It is largely dependent on surgeon preference and comfort level. In situ decompression is a simpler procedure, with less disruption to the normal anatomy and has similar results to the more extensive transposition and epicondylectomy. For this reason, the authors prefer this method as their procedure of choice for cubital tunnel syndrome. The use of a smaller incision may improve results and make the technique more similar to endoscopic decompression. The use of endoscopic techniques may further minimize the postoperative recovery time and duration of pain symptoms beyond what is seen with in situ decompression.
Appendix A. Supplementary data Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1053/j.oto.2013. 08.008.
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References 1. Karatas A, Apaydin N, Aysun U, et al: Regional anatomic structures of the elbow that may potentially compress the ulnar nerve. J Shoulder Elbow Surg 18:627-631, 2009 2. Iba K, Wada T, Aoki M, et al: The relationship between the pressure adjacent to the ulnar nerve and the disease causing cubital tunnel syndrome. J Shoulder Elbow Surg 17:585-588, 2008 3. Palmer BA, Hughes TB: Cubital tunnel syndrome. J Hand Surg 35A:153-163, 2010 4. Elhassan B, Steinmann SP: Entrapment neuropathy of the ulnar nerve. J Am Acad Orthop Surg 15:672-681, 2007 5. von Schroeder HP, Scheker LR: Redefining the “Arcade of Struthers”. J Hand Surg 28A:1018-1021, 2003 6. James J, Sutton LG, Werner FW, et al: Morphology of the cubital tunnel: An anatomical and biomechanical study with implications for treatment of ulnar nerve compression. J Hand Surg 36A:1988-1995, 2011 7. Prevel CD, Matloub HS, Ye Z, et al: The extrinsic blood supply of the ulnar nerve at the elbow: An anatomic study. J Hand Surg 18A:433-438, 1993 8. Spinner RJ: Nerve entrapment syndromes. In: Morrey BF, Sanchez-Sotelo J (eds): The Elbow and Its Disorders, (4th ed) Philadelphia, PA, Saunders, 1099-1105, 2009 9. Lowe JB, Maggi SP, Mackinnon SE: The position of crossing branches of the medial antebrachial cutaneous nerve during cubital tunnel surgery in humans. Plast Reconstr Surg 114:692-696, 2004 10. Kleinman WB, Bishop AT: Anterior intramuscular transposition of the ulnar nerve. J Hand Surg 14A:972-979, 1989 11. Heithoff SJ, Hughes TB, Palmer BA: Cubital tunnel syndrome: Ulnar nerve subluxation. J Hand Surg 35A:1556-1557, 2010 12. Cobb TK: Endoscopic cubital tunnel release. J Hand Surg 35A:1690-1697, 2010 13. Hoffmann R, Lubahn J: Endoscopic cubital tunnel release using the Hoffmann technique. J Hand Surg 38A:1234-1239, 2013 14. Tsai TM, Chen IC, Majd ME, et al: Cubital tunnel release with endoscopic assistance: Results of a new technique. J Hand Surg 24A:21-29, 1999 15. King T, Morgan FP: The treatment of ulnar neuritis: Mobilization of the ulnar nerve at the elbow by removal of the medial epicondyle and adjacent bone. Aust N Z J Surg 20:33-42, 1950 16. Craven PR, Green DP: Cubital tunnel syndrome. J Bone Joint Surg 62A:986-989, 1980 17. Froimson AI, Anouchi YS, Seitz WH, et al: Ulnar nerve decompression with medial epicondylectomy for neuropathy at the elbow. Clin Orthop Relat Res 265:200-206, 1991 18. Amako M, Nemoto K, Kawaguchi M, et al: Comparison between partial and minimal medial epicondylectomy combined with decompression for the treatment of cubital tunnel syndrome. J Hand Surg 25A:1043-1050, 2000 19. Osei DA, Padegimas EM, Calfee RP, et al: Outcomes following modified oblique medial epicondylectomy for treatment of cubital tunnel syndrome. J Hand Surg 38A:336-343, 2013 20. Henry M: Modified intramuscular transposition of the ulnar nerve. J Hand Surg 31A:1535-1542, 2006 21. Pribyl CR, Robinson B: Use of the medial intermuscular septum as a fascial sling during anterior transposition of the ulnar nerve. J Hand Surg 23A:500-504, 1998 22. Glowacki KA, Weiss AP: Anterior intramuscular transposition of the ulnar nerve for cubital tunnel syndrome. J Shoulder Elbow Surg 6:89-96, 1997 23. Eaton RG, Crowe JF, Parkes JC III: Anterior transposition of the ulnar nerve using a non-compressing fasciodermal sling. J Bone Joint Surg 62A:820-825, 1980 24. Black BT, Barron OA, Townsend PF, et al: Stabilized subcutaneous ulnar nerve transposition with immediate range of motion. J Bone Joint Surg 82A:1544-1551, 2000 25. Nouhan R, Kleinert JM: Ulnar nerve decompression by transposing the nerve and z-lengthening the flexor-pronator mass: Clinical outcome. J Hand Surg 22A:127-131, 1997 26. Macadam SA, Gandhi R, Bezuhly M, et al: Simple decompression versus anterior subcutaneous and submuscular transposition of the ulnar nerve
242 for cubital tunnel syndrome: A meta-analysis. J Hand Surg 33A:1314-1324, 2008 27. Baek GH, Kwon BC, Chung MS, et al: Comparative study between minimal medial epicondylectomy and anterior subcutaneous transposition of the ulnar nerve for cubital tunnel syndrome. J Shoulder Elbow Surg 15:609-613, 2006 28. Mitsionis GI, Manoudis GN, Paschos NK, et al: Comparative study of surgical treatment of ulnar nerve compression at the elbow. J Shoulder Elbow Surg 19:513-519, 2010 29. Charles YP, Coulet B, Rouzaud JC, et al: Comparative clinical outcomes of submuscular and subcutaneous transposition of the
B.J. Kelly and T.B. Hughes ulnar nerve for cubital tunnel syndrome. J Hand Surg 34A:866-874, 2009 30. Watts AC, Bain GI: Patient-rated outcome of ulnar nerve decompression: A comparison of endoscopic and open in situ decompression. J Hand Surg 34A:1492-1498, 2009 31. Dϋtzmann S, Martin KD, Sobottka S, et al: Open vs retractor-endoscopic in situ decompression of the ulnar nerve in cubital tunnel syndrome: A retrospective cohort study. Neurosurgery 72:605-616, 2013 32. Goldfarb CA, Sutter MM, Martens EJ, et al: Incidence of re-operation and subjective outcome following in situ decompression of the ulnar nerve at the cubital tunnel. J Hand Surg Eur 34:379-383, 2009
Background and Anatomical Considerations
C
ompression of the ulnar nerve has many causes and can occur at multiple anatomical sites (Fig. 1). The most common site of ulnar nerve compression is at the level of the elbow, and it is the second most common compressive neuropathy after carpal tunnel syndrome.1-4 The ulnar nerve originates from the medial cord of the brachial plexus and finds its origin from the C8 and T1 nerve roots. The course of the ulnar nerve is through the medial arm, posteromedial to the brachial artery, between the medial head of the triceps and the brachialis muscles. It courses through the anterior compartment proximally, pierces the medial intermuscular septum in the midbrachium, and crosses from the anterior compartment to the posterior compartment.3 The
*Department of Orthopaedic Surgery, Allegheny General Hospital, Pittsburgh, PA. †University of Pittsburgh School of Medicine, Orthopaedic Specialists, Pittsburgh, PA. Address reprint requests to Thomas B. Hughes, MD, University of Pittsburgh School of Medicine, Orthopaedic Specialists, UPMC, 9104 Babcock Blvd, Suite 5113, Pittsburgh, PA 15237. E-mail: [email protected], [email protected]
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arcade of Struthers is found approximately 8 cm proximal to the medial epicondyle and consists of a band of fascia connecting the medial intermuscular septum to the medial head of the triceps. It is made up of the medial intermuscular septum, the internal brachial ligament, and the deep fascia of the medial head of the triceps5; the anatomy is somewhat controversial, but it represents a potential site of compression.3,5 Moving distally, the next potential site of compression is the medial epicondyle. Compression here can be resultant from medial epicondyle fracture callus or malunion, heterotopic ossification, osteophytes from osteoarthritis or rheumatoid arthritis, or cubitus varus or valgus deformity.3 The next potential site of compression is the cubital tunnel. This is defined by the arcuate ligament of Osbourne medially, the medial collateral ligament of the elbow laterally, the medial epicondyle anteriorly, and the olecranon and triceps tendon posteriorly.3,6 The arcuate ligament of Osborne is a thickened band between the humeral and ulnar heads of the flexor carpi ulnaris muscle. The final potential site of nerve compression in the elbow region is the deep flexor-pronator aponeurosis, which overlies the flexor carpi ulnaris muscle as the ulnar nerve passes from the superficial to the deep region between the humeral and ulnar heads of the muscle.3 The extrinsic blood supply to the ulnar nerve is also important in understanding the surgical techniques for
Treatment options for cubital tunnel syndrome
233 Ulnar nerve compression in the elbow region must be differentiated from ulnar nerve compression in the hand at the Guyon canal. Sensation to the dorsoulnar aspect of the hand would also be intact, but there may be hypesthesias of the palmar aspect of the hand.8 In advanced disease, there is more significant clawing of the small and ring fingers with compression at the hand, as the flexor digitorum profundus muscle is not affected by nerve compression at this site.8 Provocative clinical testing can be conducted to further help differentiate these potential sites of nerve compression. Compression of the ulnar nerve at the elbow is far more common than in the palm.
Figure 1 The course of the ulnar nerve around the elbow and the common sites of compression: the arcade of Struthers, the medial intermuscular septum, the fascia of the triceps as it attaches to the medial intermuscular septum, the cubital tunnel proper (the ligament of Osbourne), the flexor-pronator aponeurosis, and the flexor carpi ulnaris muscle.
decompression. There are 2 major vascular pedicles that supply the ulnar nerve in the elbow region (Fig. 2): the superior ulnar collateral artery (SUCA) proximally and the posterior ulnar recurrent artery (PURA) distally. The inferior ulnar collateral artery lies between both of them; it is variably present, representing a minor contribution to the extrinsic blood supply.7 The SUCA and inferior ulnar collateral artery are branches of the brachial artery, while the PURA is a branch of the ulnar artery.
Clinical Presentation Patients with ulnar nerve compression generally present with a combination of elbow pain and sensory and motor symptoms.8 Symptoms are usually worse with flexion. Numbness and paresthesias are usually the predominant early features, with pain being less common initially.3 Sensory complaints usually begin with intermittent paresthesias of the small and ring fingers. These symptoms are exacerbated by elbow flexion or pressure on the medial elbow, and they may awaken the patient from sleep.8 Symptoms of sensory fiber compression can progress to actual sensory loss, which is noted over the small finger, ulnar ring finger, the ulnar palm, and the dorsoulnar aspect of the hand.3,8 Symptoms of motor fiber compression are also generally progressive. Initially, patients complain of loss of fine motor control (eg, inability to fasten buttons or lift a coin from a flat surface).3,8 The symptoms may begin with intrinsic muscle weakness and progress to weakness, atrophy, or paralysis of both the intrinsic and extrinsic muscles innervated by the ulnar nerve. Sensory symptoms and intrinsic muscle weakness are likely involved before extrinsic muscle weakness because their fibers are more peripheral within the structure of the ulnar nerve.8 When there is weakness or paralysis of the intrinsic muscles but intact function of the flexor digitorum profundus muscle, evidence of clawing can be observed in the small and ring fingers. If the flexor digitorum profundus muscle is also affected, clawing is usually absent.3,8
Conservative Treatment Before surgical intervention, conservative treatment options should be attempted. Patients should be instructed to avoid prolonged elbow flexion or direct compression of the elbow as in resting it on a table or car door.3,8 At night, using an elbow splint with the elbow maintained in a semiflexed position of approximately 451-601 of flexion may be helpful.8 Physical therapy may also be attempted with nerve mobilization techniques.3,8 These nonoperative treatment options should be attempted for 4-6 weeks before any surgical planning.8 In the event that these conservative measures fail and the symptoms of ulnar nerve compression persist, proceeding with surgical planning is indicated. When patients have constant symptoms of ulnar nerve compression, or when muscle atrophy is noted clinically, surgical intervention without a full trial of nonoperative treatment is indicated.3 Constant numbness is frequently not appreciated by the patient, as they may only note the exacerbations of paresthesias. However, simple sensory testing in the office can frequently reveal that even when patients think their hand is functioning “normally,” they do have subjectively decreased ulnar sensation.
Surgical Considerations As stated previously, there are 5 major sites of ulnar nerve compression in the elbow region (Fig. 1): the medial intermuscular septum, the arcade of Struthers, the medial
Figure 2 The 2 major vascular pedicles that supply the ulnar nerve are the superior ulnar collateral artery (SUCA) proximally and the posterior ulnar recurrent artery (PURA) distally. The inferior ulnar collateral artery (IUCA) has a minor contribution and is variably present. The SUCA and the IUCA are branches of the brachial artery, while the PURA is a branch of the ulnar artery.
234 epicondyle, the cubital tunnel, and the deep flexor-pronator aponeurosis. The most common site of compression is at the cubital tunnel, but all sites of potential compression should be evaluated and released during the surgurical procedure. The surgical techniques for ulnar nerve decompression fall into 3 major categories: in situ decompression (open or endoscopic), decompression with nerve transposition, and medial epicondylectomy.
Operative Setup The patient is positioned supine on the operating table with the operative extremity abducted onto a hand table. General anesthesia, regional anesthesia, and intravenous sedation with local anesthesia are the options for these procedures, the latter likely being insufficient for epicondylectomy or deep transpositions. An upper arm pneumatic tourniquet is utilized before positioning the extremity. With the operative extremity abducted, the shoulder is externally rotated and a bump is placed beneath the lateral aspect of the elbow to help with shoulder external rotation and mild valgus stress on the elbow, facilitating the approach to the ulnar nerve (Fig. 3). The patient is sterilely prepared and draped according to the preference of the operating surgeon. The primary surgeon sits medial to the abducted extremity in the axilla of the patient, while the assisting surgeon sits lateral to the abducted extremity to assist with retraction and exposure.
In Situ Decompression An incision is made posterior to the medial epicondyle, along the course of the ulnar nerve, through the dermis only. The length of the incision depends on the surgeon’s experience and preference. While the nerve must be decompressed over a region of approximately 12-15 cm, the skin incision required for this may only be 2-3 cm (Fig. 4A). However, when initially performing the procedure, an
Figure 3 The operative extremity abducted with the shoulder externally rotated. A bump of towels is placed beneath the lateral aspect of the elbow to help with shoulder external rotation and to provide a mild valgus stress. (Color version of figure is available online.)
B.J. Kelly and T.B. Hughes incision of 6-10 cm centered over the ulnar nerve in the cubital tunnel should be used.3 With more experience, an incision of 2-3 cm can be used. Through the small incision, deep dissection is performed by using scissors to bluntly spread through the subcutaneous fat and loosen the connective tissue to the level of the deep fascia overlying the ulnar nerve (Fig. 4B). Care is taken to identify and protect any branches of the medial antebrachial cutaneous nerve (MABC). There are usually between 1 and 3 branches of this nerve within 6 cm proximally and distally from the medial epicondyle (Fig. 5).9,10 On palpation, the ulnar nerve can be found running in its bed posterior to the medial epicondyle. It is not uncommon to find the dissection has drifted posteriorly, palpating the edge of the triceps instead of the nerve. However, the nerve is always just posterior to the epicondyle, and maintaining the dissection in this region would facilitate the entire procedure. The arcuate ligament of Osbourne is carefully punctured using blunt-tipped scissors. The decompression is performed by using dissecting scissors to spread beneath the fascia, superficial to the nerve, to develop a plane; the fascia is then lifted using forceps and incised longitudinally along the course of the nerve. Typically, only the cubital tunnel proper can be visualized through this small incision. The large end of an army-navy retractor is then placed at the proximal edge of the incision (Fig. 4C). Blunt dissection is carried out with wide spreads of the tips of the scissors to lift the subcutaneous tissues from the fascia. This also lifts any branches of the MABC with the subcutaneous fat, limiting the amount of dissection around these sensory nerves, hopefully limiting postoperative MABC symptoms. There may be some fascial bands that extend superficially from the fascia to the dermis. These may require cutting with the tips of the scissors. Care must be taken here to avoid cutting a sensory nerve or any proximal veins. Coagulation of any veins should be done with bipolar cautery before cutting them. The decompression is carried out proximally to the medial intermuscular septum and arcade of Struthers. With traction and the larger end of the army-navy retractor, the dissection can be carried at least 10-12 cm proximal to the medial epicondyle (Fig. 4C). Longer-handled, tenotomytype scissors may be beneficial here as a large part of the dissection is performed under the skin. Once the proximal dissection is completed, the army-navy retractor is placed distally (Fig. 4D), and the release performed through the distal portion of the arcuate ligament of Osbourne. The superficial fascia between the 2 heads of the Flexor Carpi Ulnaris (FCU) is released, the muscle fibers are gently separated bluntly, and then the deep fascia is released to the level where the humeral and ulnar heads unite. The nerve is retained in its bed of surrounding connective tissue, and no circumferential dissection is required. This is thought to help preserve as much extrinsic blood flow to the nerve as possible.7 It also limits nerve subluxation with elbow range of motion. The elbow is then taken through a complete range of motion to ensure that the nerve does not subluxate or snap over the medial epicondyle. Frequently, the nerve moves medially with elbow flexion, riding up
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Figure 4 (A) A medial incision is made posterior to the medial epicondyle. The line drawn on the skin represents the course of the ulnar nerve. The incision is located directly over the cubital tunnel.(B) The subcutaneous tissues are elevated from the underlying fascia. In this image, the ulnar nerve can be visualized within the cubital tunnel (U), but it has not yet been released. The large end of the army-navy retractor is inserted to its fullest extent and the subcutaneous tissues are lifted from the fascia to this point. The nerve is released to this point proximally (PR). A small branch of the MABC is identified. The army-navy retractor is repositioned deep to these branches and they are preserved.(C) The Cubital tunnel is released revealing the underlying ulnar nerve (U). The army-navy retractor protects all the subcutaneous tissues, including any MABC branches, and is superficial to the fascia (n) that is to be released. Through this approach, the fascia can be divided proximally to the arcade of Struthers.(D) The army-navy retractor is placed distally. The tip of the retractor can be visualized under the skin, marked by the tip of the scissors. By lifting the soft tissues, the nerve can be directly visualized and released distally to the point marked DR. (U, ulnar nerve; M, medial epicondyle O-tip of olecranon, P-proximal, D-distal, DR-distal extent of release, PR-proximal extent of release, MABC-medial antebrachial cutaneous nerve, n-fascia.) (Color version of figure is available online.)
along the edge of the medial epicondyle (Fig. 6). However, if it does not subluxate, the authors prefer to leave it in situ. If it does subluxate, the authors prefer to transpose the nerve at this point (refer to the section “Anterior Transposition” given later), although some surgeons do not feel it is necessary even in these cases.11 Closure can be done according to surgeon preference, but care must be taken not to create an additional source of potential nerve compression. For this reason, only the skin is closed without closing any deeper layers. A sterile soft dressing is applied without any splint immobilization, and elbow range of motion is encouraged.
Endoscopic Decompression Endoscopic decompression applies the principles of in situ decompression but through a smaller incision than is typically
used for open decompressions. It has the additional benefit of enhanced lighting and magnification through the endoscope. The patient is positioned, prepared, and draped as for the open procedures; a tourniquet is also used. It is important to place the elbow in a semiflexed position because if there is too much flexion the endoscopic instrumentation can bind up in the canal. An incision of 1.5-4 cm is made over the cubital tunnel posterior to the medial epicondyle; patients with more subcutaneous necessitate a larger incision.12 A longer incision is also recommended if a surgeon is unfamiliar with the procedure for the first few cases. The incision is taken through skin with a scalpel. The dissection is continued using scissors to spread through the subcutaneous fat and loosen the connective tissue while care is taken to avoid the branches of the MABC.9 The initial dissection is carried out to the level of the deep fascia. Long, blunt dissecting scissors are then used to develop the potential space between the adipose tissue and deep fascia proximal and distal to the incision to facilitate the
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Figure 5 The average distance from the proximal crossing branch of the MABC to the medial epicondyle is 1.8 cm (A), and the average distance from the medial epicondyle to the distal crossing branch of the MABC is 3.1 cm (B).
endoscopic exposure (Fig. 7). The superficial dissection is performed 10-14 cm both proximal and distal to the medial epicondyle.12 After the superficial dissection is completed, the ulnar nerve is identified by palpation or direct visualization. The arcuate ligament of Osbourne overlying the nerve is incised with blunttipped scissors. The cubital tunnel must be opened sufficiently to allow insertion of the endoscopic instrumentation, approximately 2 cm usually. A blunt spatula is inserted into the potential space between the ulnar nerve and the overlying deep fascia (Fig. 8); it is used to develop this space approximately 10 cm both proximal and distal to the medial epicondyle.12 The spatula should advance this distance with minimal resistance. After removing the spatula, the endoscopic cannula with a blunt-tipped trocar is inserted into this space to nearly the same distance; the attached retractor is inserted into the potential space between the deep fascia and subcutaneous fat
Figure 6 Following release, the elbow is fully flexed. The nerve may move medially, as shown here, and ride up along the medial epicondyle. If it does not sublux, it is not transposed (refer to video). (U, ulnar nerve; M, medial epicondyle; P, proximal.) (Color version of figure is available online.)
B.J. Kelly and T.B. Hughes
Figure 7 Long, blunt dissecting scissors are used to develop the potential space between the adipose tissue and deep fascia proximal and distal to the incision to facilitate the endoscopic exposure. This is carried out to a distance of approximately 10-14 cm both proximal and distal to the medial epicondyle. (Color version of figure is available online.)
and elevated to a level sufficient for good visualization of the deep fascia.12 The endoscope is initially placed between the cannula and the retractor to ensure that there are no superficial nerves in the way. The endoscope is then inserted into the cannula and turned inferiorly to identify the ulnar nerve through the slots in the cannula along its entire course. After the nerve is clearly identified, the deep fascia is divided with the endoscopic blade passed along the superior slot of the cannula (Fig. 9). This technique is carried out distally to the level of the fibrous raphe between the humeral and ulnar heads of the FCU; it is then carried out proximally to the level of the ligament of Struthers.12 If at any point resistance is encountered, the
Figure 8 A blunt spatula is inserted into the potential space between the ulnar nerve and the overlying deep fascia to develop this space to a level of approximately 10 cm both proximal and distal to the medial epicondyle. (Color version of figure is available online.)
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Figure 9 The endoscope is inserted into the cannula and turned inferiorly to identify the ulnar nerve through the slots in the cannula along its entire course. After the nerve is clearly identified, the deep fascia is divided with the endoscopic blade passed along the superior slot of the cannula. This technique is carried out distally to the level of the fibrous raphe between the humeral and ulnar heads of the FCU; it is then carried out proximally to the level of the ligament of Struthers. (Color version of figure is available online.)
cannula should be removed, the spatula reinserted, and the steps followed sequentially again. Once the release is complete, the cannula is removed. The retractor and endoscope are reinserted to confirm the completeness of release. The tourniquet is released and the same direct visualization is used to confirm adequate hemostasis; bipolar electrocautery may be used if necessary. The skin is closed and dressed as for in situ decompression. Multiple variations of this technique have recently been described in the literature, but the basic principles are the same. Blunt dissection to lift the superficial tissue and MABC branches from the underlying fascia is followed by blunt dissection between the ulnar nerve and the deep fascia. Once the fascia over the nerve is dissected free, both superficial and deep, the nerve is decompressed by incising the deep fascia. A well-described alternative technique is using long-handled tenotomy scissors to release the nerve through similar endoscopic speculum instrumentation (Fig. 10).13 In yet another technique, a retractor is used to lift the superficial tissues as a glass tube is placed beneath the deep fascia overlying the ulnar nerve; a specially designed knife is then used to incise the deep fascia along the more superficial surface of the glass tube.14 The instrumentation that is used for each step varies for each manufacturer’s technique and product line, and the surgeon should become familiar with the instrumentation used by their practice or hospital.
the initial complications of elbow instability from resecting too much of the epicondyle and disrupting the musculoligamentous complex of the medial elbow. The initial incision is 9-13 cm, and it is made just anterior to the cubital tunnel. The dissection and ulnar nerve decompression are conducted as in the in situ decompression. Once the ulnar nerve is decompressed, the medial epicondyle is exposed subperiosteally. The flexor-pronator muscular origin is left intact on the periosteal sleeve. A portion of the flexor-pronator origin may be incised and reflected distally as needed as long as some cuff
Medial Epicondylectomy
Figure 10 The illuminated speculum and endoscope are inserted into the space superficial space created above the deep fascia. Longhandled tenotomy scissors are used to release the deep fascia overlying the nerve. (Color version of figure is available online.)
Medial epicondylectomy was originally described by King and Morgan in 1950,3,15-17 and it has since been refined because of
B.J. Kelly and T.B. Hughes
238 remains on the periosteal sleeve for eventual repair.16 It is important to maintain flaps of periosteum both anteriorly and posteriorly to facilitate closure (Fig. 11A). With the medial epicondyle fully exposed, an osteotome is used to score along the metaphyseal-diaphyseal junction to identify the limit of the resection. In the earlier descriptions of this procedure, the medial margin of the trochlea was used as a guide for the bony resection15,16; however, complications related to overresection and resultant elbow instability were common. It is now common practice to identify the origin of the anterior bundle of the medial collateral ligament as part of the exposure of the medial epicondyle. It is important not to disrupt this primary stabilizer of the elbow joint during the epicondylectomy.18,19 To avoid this structure, an oblique osteotomy between the coronal and sagittal planes of the epicondyle is done using a small osteotome (Fig. 11B).19 This creates a flat surface for the
nerve to glide on while preventing destabilization of the elbow. Rongeurs or rasps are used to smooth the surface of the cut bone. The elbow is then taken through a full range of motion to ensure that there are no remaining bony prominences for the nerve to catch on or snap over. The fascia and periosteum can be repaired over the remaining epicondyle using nonabsorbable suture (Fig. 11C). If a portion of the flexor-pronator mass was taken down, it is repaired to the cuff of its origin using absorbable suture. The skin is closed as in in situ decompression and a soft dressing is applied. As there was disruption of the bony architecture, the elbow is often splinted at 901 for 1-2 weeks postoperatively before allowing full elbow range of motion; this period should last no longer than 2 weeks to prevent postoperative elbow stiffness.
Figure 11 (A) Anterior and posterior flaps are elevated by subperiosteal dissection to fully expose the medial epicondyle. Electrocautery can be used to mark out the planned osteotomy. (B) In order to avoid disrupting origin of the anterior bundle of the MCL, a small osteotome is used to create an oblique osteotomy between the coronal and sagittal planes of the epicondyle. This creates a flat surface for the nerve to glide on while preventing destabilization of the elbow. (C) The fascia and periosteum is repaired over the remaining epicondyle using nonabsorbable suture. If a portion of the flexor-pronator mass was included in the exposure, it is also included in this repair.
Treatment options for cubital tunnel syndrome
Anterior Transposition An incision is made as in in situ decompression; however, it is carried to a longer distance of 3-10 cm proximally in line with the medial intramuscular septum and 3-10 cm distally in line with the FCU fascia between its 2 heads. The length of the incision depends on the surgeon’s preference, the type of transposition to be performed, and ability to obtain adequate exposure. A longer incision is required if an intramuscular or submuscular transposition is to be performed (submuscular transposition generally requires the longest incision of all the possible procedures). If a longer incision is required, it is performed at an angle of approximately 1201, with the apex posteriorly between the medial epicondyle and the olecranon.20 The exposure and decompression are performed as described in the in situ decompression section. The nerve is then mobilized with its accompanying blood vessels from proximal to distal; particular care is taken to preserve the SUCA and PURA (Fig. 2).7 Moving distally, the ligament of Osbourne is divided and, it is done at the expense of small articular branches of the nerve, if present. All motor branches to the ulnar head of the FCU are spared. To facilitate transposition, these motor branches may need to be dissected extensively into the muscle to have adequate length to transpose the ulnar nerve.21,22 If necessary, subperiosteal mobilization of the FCU muscle belly from the olecranon process can be performed. Once the nerve is adequately mobilized, it is transposed, as described in the following section, depending on the desired final location for the nerve.
Subcutaneous Transposition The medial intermuscular septum is identified and excised from the proximal extent of the decompression to the level of the medial epicondyle to prevent compression of the ulnar nerve as it crosses the edge of the septum.10 The nerve is
239 transposed anterior to the medial epicondyle to its new position. A small sling can be created approximately at the level of the medial epicondyle to prevent the nerve from returning to its original posterior position. A 1.5-cm wide and 2-cm long strip of fascia from the flexor-pronator mass is elevated, keeping it attached medially (Fig. 12A). It is sewn using absorbable suture to the undersurface of the dermis.21,23,24 Care is taken to sew it to a more posterior portion of the dermis so that the sling does not cover and compress the nerve, but rather sits posterior to the nerve, preventing subluxation of the nerve back into the cubital tunnel (Fig. 12B). The skin is closed as in in situ decompression according to surgeon preference. A sterile soft dressing is applied without any splint immobilization, and elbow range of motion is encouraged.
Intramuscular Transposition If the surgeon wishes to place the nerve within the muscle, the release and transposition are performed as described previously. The fibrous aponeurosis between the flexor digitorum superficialis muscle of the ring finger and the FCU is released, as is proximal border of the pronator teres fascia. The excision of these structures allows the nerve to be transposed anteriorly without any kinks.10,20 The nerve is moved to its anterior position, and the position of the nerve on the underlying flexor-pronator musculature is noted; the position can be marked out using a marking pen. The nerve is temporarily replaced posterior to the medial epicondyle while its new course is prepared. The flexorpronator fascia is incised along the new anterior course of the ulnar nerve, and a trough of 5-10 mm in depth is fashioned in the flexor-pronator musculature. The fibrous septa separating the individual flexor-pronator muscles are excised to ensure a soft, well-vascularized bed for the new course of the nerve.10,20 The nerve is then moved anteriorly again into the newly created bed (Fig. 13A). The forearm is
Figure 12 (A) A small sling can be created approximately at the level of the medial epicondyle to prevent the nerve from returning to its original posterior position. A 1.5 cm wide and 2 cm long strip of fascia from the flexor-pronator mass is elevated, keeping it attached medially. (B) The strip of fascia is attached with absorbable suture to the undersurface of the dermis. Care is taken to sew it to a more posterior portion of the dermis so that the sling does not cover and compress the nerve, but rather sits posterior to the nerve, preventing subluxation of the nerve back into the cubital tunnel.
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Figure 13 (A) The flexor-pronator fascia is incised along the new anterior course of the ulnar nerve, and a trough of 5-10 mm in depth is fashioned in the flexor-pronator musculature. The fibrous septa separating the individual flexorpronator muscles are excised to ensure a soft, well-vascularized bed for the new course of the nerve. The nerve is then moved anteriorly again into the newly created bed. (B) The forearm is placed into a fully pronated position with the elbow flexed to 901, and the flexor-pronator fascia is repaired over the nerve using absorbable suture. (Color version of figure is available online.)
placed into a fully pronated position with the elbow flexed to 901, and the flexor-pronator fascia is repaired over the nerve using absorbable suture (Fig. 13B). Fractional lengthening of the fascia is usually necessary to prevent additional compression of the nerve.20 The elbow is taken through a full range of motion to demonstrate free excursion of the nerve throughout its new course and within the intramuscular tunnel. The skin is closed according to surgeon preference, and a sterile soft dressing is applied. Early range of motion is encouraged, but strengthening is delayed for 6 weeks.
Submuscular Transposition Once the ulnar nerve is circumferentially released as described previously, the flexor-pronator mass is identified and incised 1-2 cm distal to the medial epicondyle. The incision is carried out in a step-cut fashion, which allows for fractional lengthening of the muscle after the nerve is transposed beneath it.25 Once the muscle is incised and reflected distally, the ulnar collateral ligament, median nerve, and brachial artery are identified and protected. The ulnar nerve is transposed anteriorly beneath the reflected flexor-pronator mass into a position parallel and just ulnar to the median nerve. The reflected muscle is then repaired over the transposed nerve with fractional lengthening to prevent an additional source of possible nerve compression.25 The skin is closed according to surgeon preference. A sterile soft dressing is applied without any splint immobilization, and elbow range of motion is encouraged.
Summary and Evidence The choice of which of these procedures to perform is often based on surgeon preference, but there is a large amount of
research that has been done to compare these various techniques. Many studies have been done comparing simple in situ decompression of the ulnar nerve with the more complex procedures. A meta-analysis of randomized controlled trials and observational studies also compared in situ decompression with anterior transposition (subcutaneous or submuscular).26 There was no significant difference in outcomes; however, they did note a trend toward improved clinical outcomes with anterior transposition. No significant difference in clinical outcomes was found when they performed a subanalysis of subcutaneous and submuscular transposition. Baek et al27 compared medial epicondylectomy with anterior subcutaneous transposition, and there was found to be no significant difference in subjective outcomes or objective clinical findings; both procedures had high rates of patient satisfaction and good objective results. In a recent retrospective review comparing in situ decompression, medial epicondylectomy, and anterior subcutaneous transposition, they found that all 3 treatment options had overall good outcomes.28 However, they did find that the percentage of good and excellent results for anterior transposition was significantly lower than that of in situ decompression or medial epicondylectomy. The preoperative symptoms were slightly worse in this group, though, and the power of the study does not allow definitive conclusions. A retrospective review comparing submuscular and subcutaneous anterior transposition of the ulnar nerve found no significant difference in sensory, motor, or subjective recovery between both the procedures.29 They did find that patients with symptoms that had been present for more than 6 months had a worse prognosis. Overall, it is difficult to draw firm conclusions from the existing data. Randomized controlled trials are difficult to perform in this patient population, and such a trial would likely have to retain 200 patients per treatment arm to achieve statistical power.26
Treatment options for cubital tunnel syndrome A recent prospective case-control study compared subjective patient outcomes of open and endoscopic decompression and found that they were equivalent; they also found that more complications were reported with open decompression.30 Another study comparing open and endoscopic decompression again found good subjective and objective outcomes in the long term that were not significantly different; however, they found that there was a statistically significant decrease in the duration of postoperative pain and the time to return to work with endoscopic decompression.31 As endoscopic techniques improve and the procedure becomes more widely adopted, the decreased pain and recovery time may convince more surgeons to use it as their first-line surgical option. These data suggest a surgical algorithm of in situ decompression as the primary option for ulnar nerve decompression. It necessitates the least soft tissue dissection and least potential disruption of the blood supply to the nerve. Anecdotally, since changing to in situ decompression from subcutaneous transposition, the authors have found a significantly quicker recovery with fewer complaints of MABC symptoms and chronic medial elbow pain. Anterior transposition may best be reserved for revision cases refractory to in situ decompression or cases in which the ulnar nerve is found to subluxate anterior to the medial epicondyle when observed through a full range of motion after in situ decompression. Goldfarb et al,32 in a case series of 69 extremities for which in situ decompression was carried out, found that only 5 extremities had persistent or recurrent symptoms. All 5 of these extremities experienced resolution of symptoms with subsequent anterior transposition of the nerve. This supports the use of anterior transposition as the treatment option for refractory cases. It is also the author’s primary choice in patients who have symptomatic ulnar nerve subluxation preoperatively. There are those who note that some amount of nerve subluxation can be found within a normal population, so the choice of anterior transposition because subluxation is seen intraoperatively may not be necessary.11 More evidence is needed to discern whether anterior transposition truly makes a significant clinical difference when nerve subluxation is present. Currently, the evidence does not suggest that there is a superior procedure for treatment of ulnar nerve decompression. It is largely dependent on surgeon preference and comfort level. In situ decompression is a simpler procedure, with less disruption to the normal anatomy and has similar results to the more extensive transposition and epicondylectomy. For this reason, the authors prefer this method as their procedure of choice for cubital tunnel syndrome. The use of a smaller incision may improve results and make the technique more similar to endoscopic decompression. The use of endoscopic techniques may further minimize the postoperative recovery time and duration of pain symptoms beyond what is seen with in situ decompression.
Appendix A. Supplementary data Supplementary data associated with this article can be found in the online version at http://dx.doi.org/10.1053/j.oto.2013. 08.008.
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