SCIENTIFIC ARTICLE

Minimum 6-Year Follow-Up After Ulnar Nerve Decompression and Submuscular Transposition for Primary Entrapment Ryan M. Zimmerman, MD, Jesse B. Jupiter, MD, Juan González del Pino, MD, PhD

Purpose To retrospectively evaluate patients with 6-year minimum follow-up after submuscular transposition of the ulnar nerve for primary entrapment. Methods From 1992 to 2005, 142 patients were treated surgically for ulnar neuropathy at the elbow by 2 senior surgeons using a technique that preserved nerve vascularity. A total of 99 cases were eligible, and 82 elbows in 76 patients, average age 48 years, were followed for at least 6 years (average, 8.3 y). Thirty-two (42%) were male, and the dominant limb was involved in 49 (64%). The average duration of symptoms before surgery was 25 months. Clinical records were reviewed, and sensory (S0e2) and motor (M0e5) testing was performed. Dellon scores were determined, and visual analog scale and modified questionnaires from Novak et al and Kleinman and Bishop were completed. Preoperatively, 48 elbows were Dellon grade III, 33 were grade II, and one was grade I. Results There were clinically and statistically significant improvements in patient and surgeonreported data regardless of the preoperative disease severity. Visual analog scale questionnaires, sensory scale, and motor strength all improved, with at least antigravity strength in all subjects. Dellon scores also improved, and 38 elbows had normalized to Dellon 0. Of the 33 preoperative elbows that were grade III, 15 improved to grade II, 13 to grade I, and 5 normalized. Of the 48 preoperative elbows that were grade II, 16 improved to grade I and 32 normalized. Preoperative Dellon III elbows had more residual symptoms than grade II elbows. A total of 73 elbows (89%) had a good or excellent outcome. There were no reoperations or infections. Conclusions Submuscular transposition is a safe and durable option for primary ulnar neuropathy at the elbow. Overall, good or excellent results were achieved in 89% of patients with a low complication rate. (J Hand Surg Am. 2013;38(12):2398e2404. Copyright Ó 2013 by the American Society for Surgery of the Hand. All rights reserved.) Type of study/level of evidence Therapeutic IV. Key words Outcomes, transposition, ulnar neuropathy, vascularized.

U

second most common nerve compression syndrome in the upper extremity, with entrapment most often at the elbow.1,2 Numerous surgical techniques have LNAR NEUROPATHY IS THE

From the Hand and Upper Extremity Service, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA; and the Division of Hand Surgery, Department of Orthopedic Surgery, Santa Cristina University Hospital, Madrid, Spain. Received for publication October 21, 2012; accepted in revised form September 12, 2013. The authors acknowledge Dr. Kristin de Haseth and Dr. Hanah Fayaz for their efforts in data collection and manuscript preparation.

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Published by Elsevier, Inc. All rights reserved.

been described for patients whose symptoms prove refractory to conservative management, including in situ decompression3; subcutaneous,4 submuscular,5 or intramuscular anterior transpositions6; medial No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Ryan M. Zimmerman, MD, Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, WHT 535, Boston, MA 02114; e-mail: ryan. [email protected]. 0363-5023/13/38A12-0013$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2013.09.017

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TABLE 1.

Patient Self-Reported Outcome Instrument Administered at Follow-Up Visits*

Given your outcome, would you still choose to have this surgery?

Yes/no

How long did it take you to become better?

Number of months

Are you now taking medication for pain?

Yes/no

Were you off work for your ulnar nerve problem?

Yes/no/retired

Are you presently working?

Yes/no/retired

Did you change your job?

Yes/no

Was there an injury that caused you to have surgery?

Yes/no

Grade the result of your surgery from 0 (very bad) to 10 (very good)

0e10 13

*This questionnaire was based on items from the survey developed by Novak et al.

epicondylectomy7,8; and endoscopic release.9 The senior authors (J.B.J. and J.G.P.) perform a modified submuscular transposition that preserves the extrinsic vascularity of the ulnar nerve. The purpose of this study was to evaluate retrospectively the long-term outcomes of this technique using patient- and physician-rated outcomes in patients with primary ulnar neuropathy at the elbow with a minimum 6-year follow-up. MATERIALS AND METHODS With institutional review board approval, all patients treated surgically from 1992 to 2005 for ulnar nerve compression at the elbow were offered enrollment in the study. A total of 142 cases were performed during the study period using the authors’ technique. Patients undergoing primary ulnar nerve decompression and submuscular transposition with a minimum follow-up of 6 years were eligible for the study (n ¼ 142). Exclusion criteria were revision cases (23), elbow deformity resulting from premature physeal closure (3), posttraumatic sequelae (9), inflammatory arthritis (3), and a systemic neurologic diagnosis (5). Thus, 99 eligible cases remained. Seventeen patients declined enrollment, could not be located, or did not return for follow-up. The final study cohort was composed of 82 of the 99 eligible cases (83%). All patients were treated by 2 senior hand surgeons at separate medical centers using a standardized technique of submuscular transposition. Patients were evaluated preoperatively and postoperatively at standard intervals (every 6 mo for the first 3 y, annually until year 6, every 2 y from years 6e10, and every 3 y afterward) by the treating surgeons. Disease severity was classified using the Dellon scale.3 We measured sensation for each patient using static 2-point discrimination (MacKinnonDellon Disk-Criminator; Neuroregen, LLC, Bel Air, J Hand Surg Am.

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MD) and the Yale Sensory Scale (S0e2)10 using a Wartenberg esthesiometer. The Yale Sensory Scale assigns a score of S0 to S2, corresponding to increasing sensibility; S0 indicates absent sensation, S1 decreased or abnormal sensation, and S2 intact sensation.11 Unless otherwise indicated, all reporting of sensation uses the Yale Sensory Scale. We graded motor strength clinically using the British Medical Research Council Scale (M0e5)12 and measured grip strength with a standard grip meter (Jamar Dynamometer; Lafeyette Instrument Company, IN). Abductor digiti minimi and the first dorsal interosseous were tested together via abduction. The first and third volar interossei were tested together via adduction. The first dorsal interosseous muscle was also tested separately using the Froment maneuver. Antigravity strength of the first dorsal and third volar interossei was tested with the forearm in neutral rotation. We also noted intrinsic atrophy, presence of clawing or a Wartenberg sign, and the results of the Froment and crossed-finger tests. Pain was evaluated using a visual analog scale (VAS) at rest and during activity. Pain frequency was also recorded from 0 (no pain) to 10 (constant pain, including pain at night). We also measured VAS patient satisfaction, modified Kleinman and Bishop postoperative scores,6,13 as well as an 8-item questionnaire based on that developed by Novak et al14 (Table 1). The modified Kleinman and Bishop rating system assesses the presence of residual symptoms, overall improvement, work status, grip strength, and sensibility. Possible scores range from 0 to 9. Patients scoring 8 to 9 were considered to have an excellent outcome, 5 to 7 a good outcome, 3 to 4 a fair one, and 0 to 2 a poor one.6,13 We assessed continuous variables using Student t test and compared ordinal values, such as Dellon grade, using chi-square analysis. The relationship between length of follow-up and improvement based Vol 38, December 2013

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FIGURE 1: Intraoperative photographs of the authors’ technique for submuscular transposition. All images are oriented with proximal on the right. A Careful dissection allows preservation of the extrinsic vascular supply to the ulnar nerve, including the superior ulnar collateral artery (SUCA) (asterisk) running along the ulnar nerve, as well as branches running from the SUCA to triceps fibers (open circle). B The anastomosis between the posterior ulnar recurrent artery (PURA) and SUCA around the medial epicondyle (asterisk) are visible. Some branches arising from these vessels run distally and proximally along the ulnar nerve. These are epineurial vessels, from which intraneural tributaries arise to perfuse the nerve fascicles. C After transposition, the central two-thirds of the flexor-pronator mass is reattached, and the nerve is checked for smooth gliding and absence of compression.

on Dellon grade was assessed using ordinal logistic regression analysis controlling for age, symptom duration, and preoperative Dellon grade. Surgical technique was a modification of the classic procedure published by Learmonth15 (Fig. 1). Under 2.5 loupe magnification and tourniquet control through a curvilinear incision over the medial epicondyle, the Scarpa fascia was opened and branches of the medial brachial cutaneous nerve were identified and protected 6 to 7 cm proximal to the medial epicondyle. All sites of potential compression of the ulnar nerve were inspected and released.16e18 Upon division of the arcade of Struthers, the ulnar nerve was identified and carefully dissected free, preserving the mesentery-like extrinsic vascular J Hand Surg Am.

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layer. The vascular contributions from the superior ulnar collateral, posterior ulnar recurrent, and inferior ulnar collateral arteries, as well as their anastomoses about the medial epicondyle, were protected and mobilized just enough to allow tension-free transposition (Fig. 1).19e21 Typically, coagulation of several branches from the posterior ulnar recurrent artery was required for sufficient mobilization. At least 1 cm of the medial intermuscular septum was routinely excised to prevent kinking of the nerve after transposition. The flexor-pronator mass was incised deeply for 2 cm at its epicondylar attachment, and the musculofascial flap was elevated and slid distally to provide a vacant groove. The periosteal origin of the flexor carpi ulnaris was also released from the ulna, Vol 38, December 2013

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and the ulnar nerve was transposed anteriorly from the posterior condylar groove to the anterior surface of the medial epicondyle and brachialis. The central two thirds of the flexor-pronator mass was directly repaired using interrupted fascial stitches in 45 elbow flexion and forearm pronation and in 30 wrist flexion to reduce tension at the reattachment site. The elbow was then taken through a flexion-extension arc to ensure appropriate placement and absence of ulnar nerve subluxation. Plaster immobilization was continued for 2 weeks postoperatively, and therapy was initiated at the first postoperative visit. At the time of this report, 82 elbows in 76 patients had been observed for an average of 8.3  2.2 years (range, 6.0e16.1 y). For patients with bilateral procedures, separate measurements and questionnaires were made for each elbow. Thirty-two patients were male. Average age at surgery was 48  14 years. Sixteen were tobacco users. Forty-eight were employed, 15 were homemakers, 11 were retired, and 2 were students. The dominant limb was involved in 49, and average symptom duration before presentation was 25  45 months (median 14 mo; range, 1 mo to 33 y). Two-point discrimination testing preoperatively in 34 patients averaged 8.0  2.1 mm. Intrinsic atrophy was present in 12. Preoperative Dellon score was grade III in 33 patients, grade II in 48, and grade I in 1. Ipsilateral hand and elbow conditions included 15 carpal tunnel syndromes, 3 cervical radiculopathies, 3 basal joint osteoarthroses, 2 radiocapitellar osteoarthroses, 2 radial head replacements, 2 ulnar shortenings, 1 radiocarpal osteoarthritis, 1 de Quervain tenosynovitis, 1 SauvéKapandji procedure, 1 burn, and 1 elbow lateral collateral ligament injury. RESULTS Both subjective and objective data demonstrated significant improvement (Table 2). Postoperative VAS pain scores were higher in 2 elbows, 63 had no pain, and 13 had persistent pain. Visual analog scores across all dimensions improved significantly without difference based on preoperative Dellon grade. Sensory and motor functions also improved (Table 2). Postoperatively, all limbs had at least antigravity strength in the first dorsal and third volar interossei, and 64 had full strength in the abductor digiti minimi and first dorsal and first and third volar interossei. Grip strength at final follow-up was 29.1  12.2 kg on the operative side and 29.5  13.0 kg on the contralateral side, a statistically insignificant difference (P ¼ .590). J Hand Surg Am.

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TABLE 2. Preoperative and Postoperative Visual Analog Score (VAS) Pain Scores (at Rest, With Activity and Frequency), Sensibility, and Motor Strength Preoperative

Postoperative

P

VAS rest

5.3  2.8

1.0  1.8

< .001

VAS activity

6.5  2.5

1.5  2.5

< .001

VAS frequency

6.7  2.5

1.2  2.4

< .001

Sensation

1.0  0.4

1.8  0.4

< .001

Motor

3.8  0.6

4.7  0.5

< .001

Values are expressed as means  SD. Sensation is the mean Yale Sensory Score (0 to 2) at each time point. All measurements demonstrated significant improvements. There were no differences in VAS scores according to preoperative Dellon grade (P > .560 for all).

When separated according to disease severity, Dellon II elbows had better postoperative sensibility (P ¼ .020) and motor function (P ¼ .010) than Dellon III elbows. Grade II elbow sensibility improved from 1.0  0.2 to 1.9  0.3, and motor improved from 4.1  0.3 to 4.9  0.4. Grade III elbow sensibility improved from 0.8  0.4 to 1.7  0.5, and motor improved from 3.3  0.7 to 4.6  0.6. Symptoms were less frequent and less severe postoperatively. Preoperatively, Tinel sign was positive in 63 elbows, and 55 elbows had positive flexion tests. Postoperatively, tingling, numbness, and clumsiness were constant in only 1 arm, and weakness was constant in 4, all of which were preoperatively Dellon grade III. Tinel sign and elbow flexion tests were positive in 9 and 11 elbows, respectively. Atrophy of the ulnar-innervated intrinsic muscles was noted in 23 hands preoperatively and decreased to 9. Froment and Wartenberg signs were each positive preoperatively in 26 hands. The Froment sign resolved in 9 hands, and the Wartenberg sign resolved in 15 hands. Half of intrinsic clawing (11 of 22) resolved. Those with persistent clawing all had Dellon III disease preoperatively. Of the 23 abnormal cross-finger tests at presentation, 12 resolved. Ten of 11 that persisted were preoperative grade III. At presentation, 33 elbows were Dellon grade III and 48 were Dellon grade II. One elbow was Dellon grade I. At final follow-up, 38 elbows had normalized; 29 were grade I and 15 were grade II. Improvements were statistically significant for the cohort as a whole and for each group (P < .001). Forty-five elbows improved by 2 Dellon grades, and 32 improved by 1. Although the gross change in Dellon grade did not differ based on disease severity Vol 38, December 2013

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(P ¼ .820), elbows with grade II preoperative neuropathy had a lower final Dellon grade than elbows with grade III disease preoperatively (P < .001). Using ordinal logistic regression analysis, follow-up duration was associated with degree of improvement based on Dellon grade when age, symptom duration, and preoperative Dellon grade were controlled for (P ¼ .050). Unfortunately, the time point at which improvement stabilized could not be determined. Kleinman and Bishop postoperative score averaged 7.4  1.8, with excellent outcomes in 53 elbows and good outcomes in 20, representing 89% of subjects with good or excellent results. Scores were better in Dellon grade II elbows compared with Dellon grade III, 8.0  1.3 and 6.7  2.1, respectively (P < .001). Good or excellent results were obtained in 46 of 48 grade II elbows (96%) and 28 of 33 grade III elbows (85%). Mean VAS patient satisfaction score was 8.6  1.9, with no difference based on disease severity (P ¼ .960). Of 82 subjects, 77 (94%) indicated they would again choose to undergo ulnar nerve transposition, knowing their outcomes. Only 3 patients still required pain medication. There were no infections, ruptures of the repaired flexor-pronator mass, elbow contractures, or reoperations for recurrent or persistent neuropathy. DISCUSSION The optimal surgical treatment for ulnar neuropathy at the elbow remains controversial. Macadam et al22 compared simple decompression and subcutaneous and submuscular transpositions in a recent metaanalysis consisting of 906 cases. They found a trend toward improved outcomes with transposition compared with in situ decompression, and the authors concluded that pooled evidence supported transposition. The required follow-up for inclusion in their analysis was 6 months, and the single largest study included had 12-month follow-up.23 Although the necessary length of follow-up is unknown, we found that follow-up duration was positively associated with clinical improvement. McKee et al24 noted motor improvement 3 to 4 years postoperatively after posttraumatic neurolysis and transposition, which implies that multi-year follow-up may be useful. Zlowodzki et al25 performed a meta-analysis of 4 randomized, controlled trials comparing nerve conduction velocities and clinical outcome scores for patients after in situ decompression versus transposition. They found no significant differences in patients without inciting trauma or prior elbow surgery, and thus thought that the simpler procedure of J Hand Surg Am.

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decompression was sufficient. Bartels et al23 analyzed 27 years of literature and found differences based on preoperative disease severity. When all patients were considered together, simple decompression was preferred. However, patients with severe neuropathy did best with anterior transposition. In a similar metaanalysis, Mowlavi et al26 concluded that for moderate entrapment, submuscular transposition provided optimal pain relief, strength, and patient satisfaction, with the lowest rate of recurrence. A more recent but smaller prospective randomized controlled trial comparing neurolysis in situ and submuscular transposition found equivalent symptomatic improvement but more complications with transposition.27 Brauer and Graham28 performed a decision analysis that yielded neurolysis in situ as the preferred technique. A recent retrospective analysis of 113 patients treated over 10 years with average follow-up of 13 months found 75% good or excellent outcomes but inferior results with anterior transposition compared with simple decompression or medial epicondylectomy.29 Proponents of the Learmonth-type technique have obtained 80% to 95% excellent results and patient satisfaction in 5 series composed of 213 cases.27,30e33 Davis and Bulluss30 found that one third of their patients improved by 1 Dellon grade and another third improved by 2 grades. Similarly, we found that slightly over half of our elbows improved by 2 grades. Patients with preoperative Dellon III disease had more residual symptoms than those with preoperative Dellon II disease. Patients with more severe neuropathy could thus be counseled to expect improvement but perhaps not complete symptom resolution. In another 6 series composed of 272 elbows with moderate to severe entrapment observed for a mean of 55 months, good or excellent results were obtained in 80% to 97% of cases.13,14,34e37 Submuscular transposition has fared well even in high-demand patients. Fitzgerald et al32 reported on 20 young, active military personnel, noting improvement of the preoperative Disabilities of the Arm, Shoulder, and Hand questionnaire score of 33 to 6 postoperatively. All but 1 patient (95%) returned to full duty. Although the literature is replete with discussions of cubital tunnel syndrome in general, there are relatively few reports of submuscular transposition with particular attention to vascular preservation or with long follow-up. We found significant improvements in both surgeon and patient-reported outcomes with 89% good or excellent outcomes. Our technique is similar to that described by Messina and Messina.19 In their series, 30 patients were observed for 36 months, with 90% good or excellent results and no Vol 38, December 2013

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FIGURE 2: Blood supply to the ulnar nerve at the elbow. SUCA, superior ulnar collateral artery; IUCA, inferior ulnar collateral artery; PURA: posterior ulnar recurrent artery. [Messina A, Messina JC. Transposition of the ulnar nerve and its vascular bundle for the entrapment syndrome at the elbow. J Hand Surg Eur Vol. 1995;20(5):638e648.19 Copyright Ó 1995 by the Journal of Hand Surgery European Volume. Reprinted by permission of Sage.]

incidences of reoperation, results similar to our own. The similarity emphasizes that the positive early results of submuscular transposition are maintained long-term. We suggest that the durability of this procedure may result from preserving the nerve’s vascularity and providing an ideal biomechanical location. Previous work has shown benefit in preserving the vascular pedicle. There are normally 3 vascular tributaries to ulnar nerve: the superior ulnar collateral, posterior ulnar recurrent, and inferior ulnar collateral arteries (Fig. 2). Asami et al38 found improved nerve conduction velocity and clinical outcomes in patients who underwent transposition with vascular preservation compared with those without. Conversely, Maki et al39 mobilized long distances of rabbit sciatic and tibial nerves without their vascular pedicles and found that sufficient blood supply was maintained. Using a primate model, Ogata et al40 found that anterior transposition (but not in situ release or J Hand Surg Am.

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medial epicondylectomy) of the ulnar nerve resulted in a temporary regional decrease in blood flow for approximately 3 days. Although the importance of maintaining the extrinsic vascularity of the ulnar nerve during submuscular transposition is not clear, based on our favorable results and clinical experience, we recommend preserving it. Anterior submuscular transposition offers mechanical advantages, because the anatomic location of the ulnar nerve posterior to the elbow’s center of rotation exposes it to traction and compression.16 During progressive elbow flexion, the nerve is subjected to traction41 and the cross-section areas of the cubital tunnel and nerve itself decrease 30% to 40%.42 Intraneural pressure of the ulnar nerve within the cubital tunnel increases with progressive elbow flexion.42 Indeed, the nerve elongates and moves within and proximal to the cubital tunnel to accommodate mechanical forces.41,43 Such mechanisms are required, because nerve elongation as low as 15% impairs intraneural microcirculation.41 Mechanically, the optimal course for the ulnar nerve traverses the isometric center of the elbow, which is consistent with its location after submuscular transposition.35,41 Lee et al44 encountered healthy axons and minimal perineural scarring after submuscular ulnar nerve transposition in rats. Their results were worse after subcutaneous transposition. Submuscular transposition is also appealing because it is definitive. The reoperation rate for continued ulnar neuropathy after in situ decompression is 7%, and recalcitrant symptoms typically resolve after transposition.45 This reoperation rate is not trivial. However, high reoperation rates after in situ decompression compared with transposition may represent a source of bias, because persistent symptoms after in situ release can be treated by a larger transposition surgery, whereas few options remain for refractory symptoms after a submuscular transposition. For these reasons, we advocate submuscular rather than subcutaneous transposition or in situ decompression. There are several important limitations to our study. It is retrospective and reports the experience of 2 surgeons, who may have introduced bias by evaluating the outcomes of their own patients. Another weakness is the lack of a comparison group that underwent submuscular transposition without vascular preservation. The outcomes of patients who declined to participate or were lost to follow-up are unknown. Although the surgical management of primary ulnar neuropathy at the elbow remains controversial, this report demonstrates that submuscular transposition of the ulnar nerve with vascular preservation can be a safe and effective long-term treatment option. Vol 38, December 2013

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