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Anteromedial Elbow Arthroscopy Portals in Patients With Prior Ulnar Nerve Transposition or Subluxation
Anteromedial Elbow Arthroscopy Portals in Patients With Prior Ulnar Nerve Transposition or Subluxation Deenesh T. Sahajpal, M.D., F.R.C.S.C., Davide Blonna, M.D., and Shawn W. O’Driscoll, Ph.D., M.D.
Purpose: The purpose of this study was to document management strategies and complications relating to the use of anteromedial portals for elbow arthroscopy in a series of patients with subluxating or previously transposed ulnar nerves. Methods: A review of 913 elbow arthroscopies showed that 59 elbows with a subluxating or previously transposed ulnar nerve required anterior compartment arthroscopic surgery. The patients with subluxating nerves had proximal anteromedial portals established by reducing and holding the nerve behind the epicondyle with a thumb while establishing or entering the portal. In cases of prior nerve transposition, the following techniques were used if, by palpation, localization of the ulnar nerve was considered to be (1) unequivocal, (2) equivocal, or (3) impossible: In group 1 (unequivocal) the proximal anteromedial portal was established in the normal antegrade fashion. In group 2 (equivocal) a 1-cm incision was made at the planned proximal anteromedial portal site and blunt dissection down to the capsule was performed without identification of the nerve. In group 3 (impossible) a 2- to 4-cm skin incision was made and the nerve was identified before placement of the portal. Results: We found that 59 elbows in 56 patients had a subluxating ulnar nerve (31 elbows) or previous ulnar nerve transposition (28 elbows). The transposition had been subcutaneous in 21 and submuscular in 7. The proximal anteromedial portal was used in all but 3 cases (2 patients) of submuscular transposition that were early in the series. In those cases only 2 lateral portals were used for anterior compartment surgery. There were no operative ulnar nerve injuries related to the use of the proximal anteromedial portal. Conclusions: Neither elbow arthroscopy nor specifically the use of the proximal anteromedial portal is contraindicated in patients with prior transposition or subluxation of the ulnar nerve. The management of the nerve can be based on the degree of certainty with which the nerve can be localized by palpation in the region of the planned portal. Level of Evidence: Level IV, therapeutic case series.
T
he use of arthroscopy to treat various elbow disorders, including elbow stiffness, has increased in popularity in recent years. This is especially true for contracture release.1-4 This is a technically demanding
From the University of Florida (D.T.S.), Gainesville, Florida, U.S.A.; Mauriziano Hospital (D.B.), Turin, Italy; and Mayo Clinic (S.W.O.), Rochester, Minnesota, U.S.A. Presented at the Arthroscopy Association of North America Annual Meeting, San Diego, CA, April 30 –May 5, 2009. The authors report no conflict of interest. Received May 5, 2009; accepted December 22, 2009. Address correspondence and reprint requests to Shawn W. O’Driscoll, Ph.D., M.D., Mayo Clinic, 200 First St SW, Rochester, MN 55905, U.S.A. E-mail: [email protected] © 2010 by the Arthroscopy Association of North America 0749-8063/9268/$36.00 doi:10.1016/j.arthro.2009.12.029
procedure, and attention to detail is essential for a safe and reproducible arthroscopic procedure. The surgeon must have a clear understanding of the 3-dimensional anatomy of the elbow and, in particular, understand the relation of the arthroscopic portals to the neurovascular structures. Despite these recommendations, nerve injuries have been reported.5-12 Patients treated for elbow problems such as contracture have often had previous elbow procedures during which the ulnar nerve may have been transposed. In such circumstances the nerve may be at risk of direct or indirect injury from instruments in the anteromedial portals. Historically, the literature has included previous ulnar nerve transposition as a contraindication to elbow arthroscopy.13-17 More specifically, the contraindication has been thought to relate to the use of
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anteromedial portals.16-18 Some authors have even considered subluxation of the ulnar nerve to be a relative contraindication.17 Only recently has it been suggested in the literature that ulnar subluxation or prior ulnar transfer is not necessarily a contraindication to the use of anteromedial portals.3,4,14,19,20 The purpose of this study was to determine the safety of performing arthroscopic procedures in the anterior compartment of the elbow in patients in whom the ulnar nerve has previously been transposed or subluxated. We also wanted to document management strategies and offer recommendations for appropriate use of the anteromedial portals in such elbows. We hypothesized that the proximal anteromedial portal can safely be used in elbow arthroscopy with transposed or subluxating ulnar nerves if the proper choice of 3 possible strategies is used to determine the certainty with which the location of the ulnar nerve can be confirmed based on palpation.
lateral portal and, occasionally, a second retractor in the anteromedial portal. Cannulas were not used. Instead, fluid control was managed by use of a pulsed lavage system modified to and adapted to arthroscopy with pressure and flow of fluid under manual control of the assistant. Outflow was maintained by keeping the shaver open with the tubing detached so that fluid could fall freely to the floor. Suction was rarely used and never near nerves. At the end of the procedure, portals were closed with sutures, and whenever significant bony work or a capsulectomy was performed, drains were replaced anteriorly and posteriorly. The posterior drain was passed through the triceps with a trocar, and the anterior drain was inserted into the joint through the arthroscope sheath after placement of the arthroscope sheath in the proximal anterolateral portal. Local anesthesia was not injected into the joint, because prior experience has shown the potential to interfere with nerve evaluation postoperatively by temporary anesthetic effects.12
METHODS After internal review board approval, a series of patients who underwent elbow arthroscopy by a single surgeon during a 15-year period, from 1994 to 2008 inclusively, were reviewed. The inclusion criteria were (1) prior anterior transposition or subluxating ulnar nerve and (2) requirement for elbow arthroscopy that included an arthroscopic surgical procedure in the anterior aspect of the elbow necessitating the use of at least 2 anterior portals. Exclusion criteria included procedures involving only the posterior compartment or medial/lateral gutters. Technique of Elbow Arthroscopy The location of the patient’s ulnar nerve was determined preoperatively by history, physical examination, and review of previous operative records when available. Arthroscopy was performed with the patient in the lateral decubitus position with a tourniquet inflated. The arm rested on a custom-made arm holder. All patients underwent arthroscopic procedures involving both the anterior and posterior compartments of the elbow. Posterior compartment arthroscopy was performed first, through the posterolateral and posterior portals and, when necessary, additional portals in the soft spot and accessory portals for retractors. Anterior compartment arthroscopy was performed next, by use of 2 standard working portals, the anterolateral portal and the proximal anteromedial portal. In most cases a retractor was also used in the proximal antero-
Elbows With Subluxating Ulnar Nerve Subluxation of the nerve was defined as the nerve rolling up onto, or onto and over, the medial epicondyle during elbow flexion such that it could be felt to suddenly pass beneath a finger or thumb pressed against the epicondyle. The nerve was palpated with the arm relaxed at 90° and supported in the arm holder. The excursion of the nerve relative to the medial epicondyle was noted. The nerve was pushed anteriorly and posteriorly to fully understand its mobility relative to the medial epicondyle (Figs 1A and 1B). In addition, the elbow was flexed and extended during palpation of the nerve to determine whether there was dynamic subluxation. Once the nerve’s location had been satisfactorily established, it was reduced behind the epicondyle and held in position by the surgeon’s thumb to block anterior subluxation, and the proximal anteromedial portal was created. A No. 15 scalpel blade was used to incise the skin, without penetration into the subcutaneous tissue, 2 to 3 cm proximal and 1 cm anterior to the medial epicondyle. The posteriorly directed pressure was maintained on the nerve as a custom-made pointed, blunt switching stick was introduced into the joint anterior to the intermuscular septum (Fig 1C). Although some surgeons prefer to spread the skin with a hemostat, this technique was not used. The arthroscope sheath was then gently inserted into the joint over the switching stick.
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FIGURE 1. Elbows with subluxating ulnar nerve. (A) The nerve was pushed anteriorly and posteriorly to fully understand its mobility relative to the medial epicondyle. (B) Once the nerve location had been satisfactorily established, it was reduced behind the epicondyle and held in position by the surgeon’s thumb to block anterior subluxation while the proximal anteromedial portal was created. (C) The posteriorly directed pressure was maintained on the nerve as a custom-made pointed, blunt-tip switching stick was introduced into the joint anterior to the intermuscular septum. The arthroscope sheath was then gently inserted into the joint over the switching stick.
Elbows With Prior Ulnar Nerve Transposition Usually, the documentation of a prior ulnar nerve transposition is clear from operative records. Unfortunately, records are not always available and are sometimes unclear. If the nerve is known to be in the subcutaneous position, both the proximal anteromedial (preferred) and anteromedial (secondary) portals can be used according to the guideline described later. However, if the nerve is (or could be) submuscular or intramuscular, only the proximal anteromedial portal was used, because the anteromedial portal is more distal and may cross the path of the nerve. Definitions of Ulnar Nerve Localization Decision making and surgical approach to the proximal anteromedial portal were ultimately based on the physical examination in the clinic preoperatively and confirmed again intraoperatively. As defined later, the key determination is the ability to precisely localize the ulnar nerve by palpation in the region of the planned anteromedial portal. Ulnar nerve localization at the planned portal site was considered to be (1) unequivocal, (2) equivocal, or (3) impossible (Fig 1). In group 1 ulnar nerve localization at the planned portal site was considered to be unequivocal if the nerve was palpable along its entire course in the transposed position (or along its entire course with the exception of the very proximal or distal portions) and there was no tubular structure or ulnar paresthesia with palpation
behind the epicondyle. In most cases the transposed nerve was also mobile so that it could be rolled back and forth under the skin and/or the patient had localized paresthesia in the ulnar nerve distribution in the hand when the nerve was rolled with some compression (like “hitting the funny bone”). In group 2 ulnar nerve localization at the planned portal site was considered to be equivocal if the nerve was palpable along only part of its course or if palpation at the planned portal site showed neither a distinct nor mobile nerve nor localizing paresthesia or if there was a tubular structure behind the medial epicondyle, which might have been the nerve. Finally, in group 3 ulnar nerve localization at the planned portal site was considered to be impossible if the nerve was not palpable anywhere in that region. Most commonly, this occurred in obese patients, whose thick layer of adipose tissue obscured the nerve. Portal Placement Based on Ulnar Nerve Localization In group 1, in which ulnar nerve localization at the planned portal site was unequivocal, the proximal anteromedial portal was established in the normal antegrade fashion with the following technique. If the nerve was mobile, it was rolled back and forth several times to confirm the location. Then, with the nerve rolled posteriorly and held there by a finger, the prox-
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FIGURE 2. Transposed ulnar nerve. In group 1, in which ulnar nerve localization at the planned portal site was unequivocal, the proximal anteromedial portal was established in the normal antegrade fashion with the following precaution. If the nerve was mobile, it was rolled back and forth several times to confirm the feel of doing so. Then, with the nerve rolled posteriorly and held there by a finger, the proximal anteromedial portal was established anterior to the nerve. If the nerve was not mobile, the proximal anteromedial portal was placed either anterior or posterior to the nerve, whichever offered the greatest clearance from the nerve and best line of approach to the joint.
imal anteromedial portal was established anterior to the nerve (Fig 2). If the nerve was not mobile, the proximal anteromedial portal was placed either anterior or posterior to the nerve, whichever offered the greatest clearance from the nerve and best line of approach to the joint. This course was almost always anterior to the nerve. A blunt-tip, pointed 4-mm switching stick was then used to penetrate the capsule and enter the joint. The arthroscope sheath was then gently passed down over the switching stick into the joint. In group 2, in which ulnar nerve localization at the planned portal site was equivocal, a 1-cm incision was made in the skin at the planned site of the proximal anteromedial portal. The location was either anterior or posterior to the nerve, whichever offered the great-
est clearance from the nerve and best line of approach to the joint. Blunt dissection (spreading longitudinally in parallel with the nerve) was then used to dissect past the nerve to the joint capsule without identification of the nerve. A blunt-tip, pointed 4-mm switching stick was then used to penetrate the capsule and enter the joint. The arthroscope sheath was then gently passed down over the switching stick into the joint. Because the edge of the sheath could catch the nerve, the sheath was advanced slowly and without force while rotating it back and forth (around the switching stick). Finally, in group 3, in which ulnar nerve localization at the planned portal site was impossible, a 2- to 4-cm skin incision was made at the planned site of the proximal anteromedial portal. The ulnar nerve was identified and the best line of approach to the joint determined. After incising through the dermis, the surgeon used blunt dissection down to the deep fascia. Digital palpation was used to locate the nerve, and then only sufficient longitudinal blunt dissection was used to confirm that the palpable structure thought to be the nerve was, indeed, the nerve. Blunt dissection past the nerve was followed by passage of a blunt-tip, pointed 4-mm switching stick down to the capsule under direct visualization while protecting the nerve. After penetration of the capsule, the arthroscope sheath was then passed down over the switching stick into the joint. Methods of Portal Placement Tried During Early Years During the learning curve involving the first few cases, other methods were used before the current decision-making algorithm was derived. In group 2, in which ulnar nerve localization at the planned portal site was equivocal, 2 patients had the proximal anteromedial portal established in a retrograde manner by use of a switching stick and the inside-out technique. This was later abandoned based on the reasoning that if the ulnar nerve was stuck in scar tissue, the insideout technique would not necessarily prevent a significant blunt injury to the nerve (or conceivably even disruption). In 3 cases (2 patients) in group 3, in whom ulnar nerve localization at the planned portal site was impossible, 2 anterolateral portals (anterolateral and proximal anterolateral) were used without any anteromedial portal. In those cases the nerve had been transposed in a submuscular manner and was not palpable. They were early in the series, when standard teaching
ANTEROMEDIAL ELBOW ARTHROSCOPY PORTALS was that a transposed nerve was a contraindication to use of anteromedial portals. For subsequent cases such as this, we chose to explore the nerve through a 2- to 4-cm incision as described previously and then create a proximal anteromedial portal. Another method used early in the series was insertion of a plastic cannula in the proximal anteromedial portal. The reasoning was that moving instruments in and out of a cannula would lessen the risk of harm to the nearby transposed ulnar nerve during instrument exchange. This was only done twice, because the cannula seemed to be more a hindrance than a help. The senior author has developed rapid portal-switching techniques that are safe and effective and that obviate the use of cannulas. Specific Considerations With Submuscular Transpositions The term “submuscular transposition” has been used to mean any procedure involving placement of the nerve under the common flexor-pronator musculature adjacent to the median nerve. Because of the unpredictability of knowing exactly where the nerve might be, and the fact that it might be adjacent to the anterior capsule, the senior author considered prior submuscular transposition of the ulnar nerve to be a relative contraindication to anterior capsulectomy. RESULTS Elbows With Prior Ulnar Nerve Transposition Of the 913 elbow arthroscopies performed during the 15-year study period, 59 met the inclusion criteria of having a subluxating or previously transposed ulnar nerve and requiring therapeutic anterior compartment surgery involving at least 2 portals. Of these, 28 elbows (cases) in 26 patients with a prior ulnar nerve transposition underwent therapeutic arthroscopic surgery. Of these cases, 7 had a prior submuscular transposition and 21 had subcutaneous transposition. During this same 15-year period, no patients with a prior ulnar nerve transposition were considered ineligible for arthroscopic surgery and therefore had an open procedure, based on the nerve having been transposed. At the time of surgery, the mean age was 39 years (range, 12 to 76 years). There were 21 male patients. The diagnosis was a post-traumatic contracture in 15 cases, primary osteoarthritis in 6, inflammatory arthritis in 2, and post-traumatic plica and/or loose bodies in 5. The mean number of elbow surgeries before the index procedure was 2 (range, 1 to 4).
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The indication for surgery was a contracture release in 23 cases and mechanical symptoms due to a snapping plica or loose bodies in 5. All of the patients had normal nerve function 3 days after surgery. At a mean follow-up of 20 months (range, 1 to 72 months), no patients showed neurologic symptoms. In 4 cases only a first postoperative evaluation 3 days after surgery was available for review. Each of these patients had normal nerve function right after surgery and at day 3 postoperatively. Normal nerve function was defined as full motor strength in the ulnar, median, and radial nerve distribution (extrinsic and intrinsic muscles); the ability to distinguish little touches at the tips of each of the 5 digits and in the first dorsal interosseous space with the eyes closed; and the subjective impression that the hand felt normal to the patient. During the arthroscopic procedure, the proximal anteromedial portal was used in 25 cases. In the remaining 3 cases, only 2 anterolateral portals were used. The details of the different techniques used to place the proximal anteromedial portal are reported in Fig 3. Two patients had a modification of the procedure early in the series when we were less confident as to how to manage the elbow after submuscular transposition of the nerve. In those 2 cases, 2 lateral portals were used with no medial portals, and in 1 case a partial anterior capsulectomy was performed in the other case of debridement. Elbows With Ulnar Nerve Subluxation Thirty-one elbows (cases) in thirty patients had ulnar nerve subluxation. The mean age was 30 years (range, 11 to 57 years). There were 26 male patients. The diagnosis was osteoarthritis in 9 cases, posttraumatic contracture in 5, post-traumatic plica associated with loose bodies or lateral epicondylitis in 4, loose bodies in 5, osteoid osteoma in 3, rheumatoid
FIGURE 3. Proximal anteromedial portal placement after ulnar nerve transposition.
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arthritis in 2, osteochondritis dissecans in 2, and posteromedial impingement in 1. Nine cases had had prior surgery not related to the ulnar nerve. Of these, 4 had open surgeries, 3 had arthroscopic surgeries, and 2 had both open and arthroscopic surgeries. Nineteen cases underwent an arthroscopic capsulectomy or capsulotomy. In all cases the proximal anteromedial portal was placed while the ulnar nerve was held in a reduced position. All of the patients were examined on the day of discharge and on day 3 or later postoperatively. The mean follow-up was 23 months (range, 1 to 108 months). Four patients did not return for later follow-up but had a normal neurologic examination after surgery and on day 3. No patients in this group had any direct operative injury to the ulnar nerve. In this group of patients with a subluxating ulnar nerve, a tardy ulnar neuropathy developed in 4 in the early postoperative period after a normal neurologic examination immediately after surgery. Each of these patients had a contracture release performed, followed by 3 days of continuous passive motion in the hospital with an indwelling continuous brachial plexus block anesthetic. After discontinuation of the block, the ulnar neuropathies were apparent on day 3 or day 4. Each patient showed both sensory and motor loss that was progressive and associated with progressive loss of motion in the elbow. They were treated by ulnar nerve decompression and subcutaneous transposition on days 4 to 8. One patient had recovered completely at 4 weeks’ follow-up, and one was almost normal (slight sensory impairment) at 4 months. One patient recovered completely within 2 years. One patient, during her last follow-up available (3 months), still had moderate ulnar weakness. Exploration of these ulnar nerves at the time of transposition failed to show any contusion or direct lesion to the nerve, including in the proximity of the proximal anteromedial portal. In all 4 cases compression of the ulnar nerve was observed at the cubital tunnel retinaculum. These patients had increases in extension, flexion, and total arc of motion. Preoperatively, extension was 43° (range, 40° to 45°), flexion was 118° (range, 110° to 125°), and the total arc of motion was 75° (range, 70° to 80°). Postoperatively, extension was 3° (range, 0° to 10°), flexion was 135° (range, 135° to 140°), and the total arc of motion was 132° (range, 125° to 140°). They gained a mean of 60° in the arc of motion (range, 55° to 70°), with flexion increasing from 118° to 138°, for a mean of 40° (range, 10° to 25°). None of them had undergone prophylactic ulnar nerve decompres-
sion at the time of contracture release. They were all managed by subcutaneous ulnar nerve transposition 4 to 8 days after the index surgery. An infection was diagnosed in 1 patient 3 weeks after an arthroscopic plica excision and open tennis elbow repair. Six months after irrigation and debridement, he was considered healed. Use of Second Anteromedial Portal The data presented previously all refer specifically to the use of the proximal anteromedial portal. It is preferred over the originally described anteromedial portal (located at the joint line), which penetrates the flexor-pronator tendon. The principal indication for the anteromedial portal is to place a second retractor into the anterior compartment of the elbow.21 A second anteromedial portal was used in 8 elbows. Of these 8 cases, 7 were patients with subluxating ulnar nerves. In only 1 patient with a prior transposition was the anteromedial portal used in addition to the proximal anteromedial portal. This patient was in group 1, in whom the nerve was able to be localized unequivocally throughout its course. Thus avoiding it during placement of a second portal was no more difficult than with the first portal. We considered the anteromedial portal (i.e., at the joint line) to be contraindicated in a patient with a submuscular transposition, because the nerve is obscured by the flexor-pronator origin, which must be penetrated to establish that portal. DISCUSSION Despite advances in elbow arthroscopy, there have been reports of neurologic injury of all 3 major nerves of the elbow.5-10 An important first step in safe elbow arthroscopy is to recognize the circumstances in which the risk of nerve injury is increased. The anatomic relation between portal sites and the nerves has been well documented.22-24 However, any condition that alters this normal relation theoretically increases the risk of nerve injury during portal placement or use. Although many authors have described previous ulnar nerve transposition as at least a relative contraindication to the use of anteromedial portals, there are no data in the literature documenting the risk of nerve injury in such circumstances.13-18 This study is the first that documents the safety of certain strategies permitting the use of the proximal anteromedial portal in a consecutive series of patients requiring therapeutic arthroscopic procedures in the anterior compart-
ANTEROMEDIAL ELBOW ARTHROSCOPY PORTALS ment of the elbow after prior ulnar nerve transposition. A similar strategy was successfully and safely used in patients with subluxating ulnar nerves. The strategy that was used to avoid injuring a transposed or subluxating ulnar nerve in this series of patients was rather simple. It was based entirely on the degree of certainty with which the nerve could be identified and localized before placement of the proximal anteromedial portal. If the location of the transposed ulnar nerve was unequivocal, we made a portal about 1 cm away from the nerve and avoided the nerve. If the location of the nerve was equivocal (i.e., we were fairly confident but not certain), we made the skin incision for the portal about 1 cm away from the nerve and then bluntly dissected down to the capsule, passing the nerve without identifying it. A pointed, blunt-tip switching stick was passed down the same path and used to penetrate the joint capsule. Over the switching stick, the arthroscope sheath was gently passed into the joint. Finally, if localization of the nerve was impossible, we made a 2- to 4-cm incision and identified the nerve before establishing the portal (otherwise as for the equivocal nerve). During the same 15-year period, 402 elbows underwent open capsular releases. However, in none of these cases was the decision to perform open surgery instead of arthroscopic surgery influenced by whether the ulnar nerve had been transposed previously or subluxated. Although we tried other techniques early in the series, this strategic approach became standard and reproducible with time. Before conceiving of this approach based on localizing the nerve, we tried using only 2 anterolateral portals in 3 cases (2 patients). However, we abandoned this technique because it limited our ability to achieve the goals of surgery. We also used an inside-out technique in 2 cases but abandoned that as well. Our concern was that if the nerve was embedded in scar tissue, it might not displace away from the switching stick being passed from inside out. That would potentially expose the nerve to risk of injury as well. We thought that gentle blunt dissection from outside in would be a safer way to pass by the nerve. Because we used the inside-out technique only twice, its safety cannot be derived from our data. Subluxation or dislocation of the ulnar nerve proved to be straightforward to manage. We simply reduced and held it behind the epicondyle while establishing or re-entering the anteromedial portals. We did not use magnetic resonance imaging and intraoperative ultrasound in any of the patients. Nor-
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mal nerves can be localized reliably with these techniques, but we were uncertain as to their reliability for the transposed nerve in the setting of anatomic distortion and scarring from prior surgery and possibly trauma. In addition, magnetic resonance imaging is performed with the elbow extended, whereas elbow arthroscopy is performed at about 90° of flexion. This change in position could theoretically alter anatomic relations around the nerve. Intraoperative ultrasound would probably be helpful but would be more cumbersome, time-consuming, and expensive than the approach used in our patients. It also requires an experienced operator, which many surgeons are not. Our recommendation for use of the proximal anteromedial portal applies to elbows in which the nerve has been transposed into either the subcutaneous or submuscular position. However, the traditional anteromedial portal (at the level of the joint) is probably unsafe in patients with submuscular transposition. In addition, the safety of arthroscopic capsulectomy after submuscular transposition is uncertain. Although the senior author has extensive experience with arthroscopic capsulectomy including arthroscopic nerve dissection, a transposed nerve may be scarred to surrounding structures and difficult to dissect free of them. This is in contrast to a native undissected nerve (such as the radial nerve, which also lies adjacent to the anterior capsule of the elbow). Thus, if the ulnar nerve is scarred to the anterior capsule, the nerve might be at greater risk of being damaged during arthroscopic capsulectomy. Until more experience is documented, such cases should be considered individually based on the experience of the surgeon. A limitation of this study is that 4 patients in the subluxation group had follow-up of only 3 days. Because ulnar nerve subluxation could possibly be a risk factor for tardy ulnar neuropathy postoperatively, it is possible that tardy ulnar neuropathy may have developed in those patients without our knowledge. If so, this would have increased the statistical likelihood of this being a risk factor for this complication. Tardy ulnar neuropathy after contracture release has been reported by Huffmann et al.25 The 4 patients in our series were typical of those affected by this complication, with a significant gain in motion, particularly flexion. In addition, this is a retrospective study in which the categorization of ulnar nerve location was applied retroactively. In other words, in the early part of the series, the algorithm itself had not been formulated and thus the categorization of patients was based on retrofitting their data to the algorithm presented.
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The proximal anteromedial portal can be used in a manner that is safe for patients who have had transposition of the ulnar nerve or whose nerve subluxates. Modifications to standard techniques are necessary, based on the certainty with which the ulnar nerve can be localized by palpation in the region of the planned portal. We conclude that neither elbow arthroscopy nor specifically the use of the proximal anteromedial portal is contraindicated in patients with prior transposition or subluxation of the ulnar nerve. The management of the nerve can be based on the degree of certainty with which the nerve can be localized by palpation in the region of the planned portal. Acknowledgment: The authors appreciate the input and assistance of John Eric Gee, M.D., in the preparation of this work.
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22. 23. 24. 25.
lease of post-traumatic elbow contracture. Arthroscopy 1999;15:784-787. Hahn M, Grossman JA. Ulnar nerve laceration as a result of elbow arthroscopy. J Hand Surg Br 1998;23:109. Dumonski ML, Arciero RA, Mazzocca AD. Ulnar nerve palsy after elbow arthroscopy. Arthroscopy 2006;22:577.e1-577.e3. Available online at www.arthroscopyjournal.org. Kelly E. Avoiding nerve injury in elbow arthroscopy. Ed 1. Rosemont, IL: American Academy of Orthopaedic Surgeons, 2007. Kelly E, Morrey B, O’Driscoll S. Complications of elbow arthroscopy. J Bone Joint Surg Am 2001;83:25-34. Baker CL Jr, Jones GL. Arthroscopy of the elbow. Am J Sports Med 1999;27:251-264. Gramstad GD, Galatz LM. Management of elbow osteoarthritis. J Bone Joint Surg Am 2006;88:421-430. Dodson CC, Nho SJ, Williams RJ III, Altchek DW. Elbow arthroscopy. J Am Acad Orthop Surg 2008;16:574-585. Rosenberg BM, Loebenberg MI. Elbow arthroscopy. Bull NYU Hosp Jt Dis 2007;65:43-50. Baker CL Jr. Arthroscopic management of lateral humeral epicondylitis (tennis elbow). New York: Springer Science & Business, 2001. Cain E. Elbow arthroscopy in throwing athlete. In: McGinty J, ed. Operative arthroscopy. Philadelphia: Lippincott Williams & Wilkins, 2003;697-706. Abboud JA, Ricchetti ET, Tjoumakaris F, Ramsey ML. Elbow arthroscopy: Basic setup and portal placement. J Am Acad Orthop Surg 2006;14:312-318. Steinmann SP, Elhassan B. Elbow arthroscopy after ulnar nerve transposition. In: Yamaguchi K, King G, McKee M, O’Driscoll S, eds. Advanced reconstruction elbow. Ed 1. Rosemont, IL: American Academy of Orthopaedic Surgeons, 2007; 93-96. O’Driscoll SW. Arthroscopic osteocapsular arthroplasty. In: Yamaguchi K, King G, McKee M, O’Driscoll S, eds. Advanced reconstruction elbow. Ed 1. Rosemont, IL: American Academy of Orthopaedic Surgeons, 2007;59-68. Field LD, Altchek DW, Warren RF, O’Brien SJ, Skyhar MJ, Wickiewicz TL. Arthroscopic anatomy of the lateral elbow: A comparison of three portals. Arthroscopy 1994;10:602-607. Lynch G, Meyers J, Whipple T, Caspari R. Neurovascular anatomy and elbow arthroscopy: Inherent risks. Arthroscopy 1986;2:191-197. Stothers K, Day B, Regan WR. Arthroscopy of the elbow: Anatomy, portal sites, and a description of the proximal lateral portal. Arthroscopy 1995;11:449-457. Huffmann GR, O’Driscoll SW. Delayed onset of ulnar neuropathy after arthroscopic elbow contracture release. Presented at the Annual Meeting of the Arthroscopy Association of North America, Hollywood, FL, May 2006.
Purpose: The purpose of this study was to document management strategies and complications relating to the use of anteromedial portals for elbow arthroscopy in a series of patients with subluxating or previously transposed ulnar nerves. Methods: A review of 913 elbow arthroscopies showed that 59 elbows with a subluxating or previously transposed ulnar nerve required anterior compartment arthroscopic surgery. The patients with subluxating nerves had proximal anteromedial portals established by reducing and holding the nerve behind the epicondyle with a thumb while establishing or entering the portal. In cases of prior nerve transposition, the following techniques were used if, by palpation, localization of the ulnar nerve was considered to be (1) unequivocal, (2) equivocal, or (3) impossible: In group 1 (unequivocal) the proximal anteromedial portal was established in the normal antegrade fashion. In group 2 (equivocal) a 1-cm incision was made at the planned proximal anteromedial portal site and blunt dissection down to the capsule was performed without identification of the nerve. In group 3 (impossible) a 2- to 4-cm skin incision was made and the nerve was identified before placement of the portal. Results: We found that 59 elbows in 56 patients had a subluxating ulnar nerve (31 elbows) or previous ulnar nerve transposition (28 elbows). The transposition had been subcutaneous in 21 and submuscular in 7. The proximal anteromedial portal was used in all but 3 cases (2 patients) of submuscular transposition that were early in the series. In those cases only 2 lateral portals were used for anterior compartment surgery. There were no operative ulnar nerve injuries related to the use of the proximal anteromedial portal. Conclusions: Neither elbow arthroscopy nor specifically the use of the proximal anteromedial portal is contraindicated in patients with prior transposition or subluxation of the ulnar nerve. The management of the nerve can be based on the degree of certainty with which the nerve can be localized by palpation in the region of the planned portal. Level of Evidence: Level IV, therapeutic case series.
T
he use of arthroscopy to treat various elbow disorders, including elbow stiffness, has increased in popularity in recent years. This is especially true for contracture release.1-4 This is a technically demanding
From the University of Florida (D.T.S.), Gainesville, Florida, U.S.A.; Mauriziano Hospital (D.B.), Turin, Italy; and Mayo Clinic (S.W.O.), Rochester, Minnesota, U.S.A. Presented at the Arthroscopy Association of North America Annual Meeting, San Diego, CA, April 30 –May 5, 2009. The authors report no conflict of interest. Received May 5, 2009; accepted December 22, 2009. Address correspondence and reprint requests to Shawn W. O’Driscoll, Ph.D., M.D., Mayo Clinic, 200 First St SW, Rochester, MN 55905, U.S.A. E-mail: [email protected] © 2010 by the Arthroscopy Association of North America 0749-8063/9268/$36.00 doi:10.1016/j.arthro.2009.12.029
procedure, and attention to detail is essential for a safe and reproducible arthroscopic procedure. The surgeon must have a clear understanding of the 3-dimensional anatomy of the elbow and, in particular, understand the relation of the arthroscopic portals to the neurovascular structures. Despite these recommendations, nerve injuries have been reported.5-12 Patients treated for elbow problems such as contracture have often had previous elbow procedures during which the ulnar nerve may have been transposed. In such circumstances the nerve may be at risk of direct or indirect injury from instruments in the anteromedial portals. Historically, the literature has included previous ulnar nerve transposition as a contraindication to elbow arthroscopy.13-17 More specifically, the contraindication has been thought to relate to the use of
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anteromedial portals.16-18 Some authors have even considered subluxation of the ulnar nerve to be a relative contraindication.17 Only recently has it been suggested in the literature that ulnar subluxation or prior ulnar transfer is not necessarily a contraindication to the use of anteromedial portals.3,4,14,19,20 The purpose of this study was to determine the safety of performing arthroscopic procedures in the anterior compartment of the elbow in patients in whom the ulnar nerve has previously been transposed or subluxated. We also wanted to document management strategies and offer recommendations for appropriate use of the anteromedial portals in such elbows. We hypothesized that the proximal anteromedial portal can safely be used in elbow arthroscopy with transposed or subluxating ulnar nerves if the proper choice of 3 possible strategies is used to determine the certainty with which the location of the ulnar nerve can be confirmed based on palpation.
lateral portal and, occasionally, a second retractor in the anteromedial portal. Cannulas were not used. Instead, fluid control was managed by use of a pulsed lavage system modified to and adapted to arthroscopy with pressure and flow of fluid under manual control of the assistant. Outflow was maintained by keeping the shaver open with the tubing detached so that fluid could fall freely to the floor. Suction was rarely used and never near nerves. At the end of the procedure, portals were closed with sutures, and whenever significant bony work or a capsulectomy was performed, drains were replaced anteriorly and posteriorly. The posterior drain was passed through the triceps with a trocar, and the anterior drain was inserted into the joint through the arthroscope sheath after placement of the arthroscope sheath in the proximal anterolateral portal. Local anesthesia was not injected into the joint, because prior experience has shown the potential to interfere with nerve evaluation postoperatively by temporary anesthetic effects.12
METHODS After internal review board approval, a series of patients who underwent elbow arthroscopy by a single surgeon during a 15-year period, from 1994 to 2008 inclusively, were reviewed. The inclusion criteria were (1) prior anterior transposition or subluxating ulnar nerve and (2) requirement for elbow arthroscopy that included an arthroscopic surgical procedure in the anterior aspect of the elbow necessitating the use of at least 2 anterior portals. Exclusion criteria included procedures involving only the posterior compartment or medial/lateral gutters. Technique of Elbow Arthroscopy The location of the patient’s ulnar nerve was determined preoperatively by history, physical examination, and review of previous operative records when available. Arthroscopy was performed with the patient in the lateral decubitus position with a tourniquet inflated. The arm rested on a custom-made arm holder. All patients underwent arthroscopic procedures involving both the anterior and posterior compartments of the elbow. Posterior compartment arthroscopy was performed first, through the posterolateral and posterior portals and, when necessary, additional portals in the soft spot and accessory portals for retractors. Anterior compartment arthroscopy was performed next, by use of 2 standard working portals, the anterolateral portal and the proximal anteromedial portal. In most cases a retractor was also used in the proximal antero-
Elbows With Subluxating Ulnar Nerve Subluxation of the nerve was defined as the nerve rolling up onto, or onto and over, the medial epicondyle during elbow flexion such that it could be felt to suddenly pass beneath a finger or thumb pressed against the epicondyle. The nerve was palpated with the arm relaxed at 90° and supported in the arm holder. The excursion of the nerve relative to the medial epicondyle was noted. The nerve was pushed anteriorly and posteriorly to fully understand its mobility relative to the medial epicondyle (Figs 1A and 1B). In addition, the elbow was flexed and extended during palpation of the nerve to determine whether there was dynamic subluxation. Once the nerve’s location had been satisfactorily established, it was reduced behind the epicondyle and held in position by the surgeon’s thumb to block anterior subluxation, and the proximal anteromedial portal was created. A No. 15 scalpel blade was used to incise the skin, without penetration into the subcutaneous tissue, 2 to 3 cm proximal and 1 cm anterior to the medial epicondyle. The posteriorly directed pressure was maintained on the nerve as a custom-made pointed, blunt switching stick was introduced into the joint anterior to the intermuscular septum (Fig 1C). Although some surgeons prefer to spread the skin with a hemostat, this technique was not used. The arthroscope sheath was then gently inserted into the joint over the switching stick.
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FIGURE 1. Elbows with subluxating ulnar nerve. (A) The nerve was pushed anteriorly and posteriorly to fully understand its mobility relative to the medial epicondyle. (B) Once the nerve location had been satisfactorily established, it was reduced behind the epicondyle and held in position by the surgeon’s thumb to block anterior subluxation while the proximal anteromedial portal was created. (C) The posteriorly directed pressure was maintained on the nerve as a custom-made pointed, blunt-tip switching stick was introduced into the joint anterior to the intermuscular septum. The arthroscope sheath was then gently inserted into the joint over the switching stick.
Elbows With Prior Ulnar Nerve Transposition Usually, the documentation of a prior ulnar nerve transposition is clear from operative records. Unfortunately, records are not always available and are sometimes unclear. If the nerve is known to be in the subcutaneous position, both the proximal anteromedial (preferred) and anteromedial (secondary) portals can be used according to the guideline described later. However, if the nerve is (or could be) submuscular or intramuscular, only the proximal anteromedial portal was used, because the anteromedial portal is more distal and may cross the path of the nerve. Definitions of Ulnar Nerve Localization Decision making and surgical approach to the proximal anteromedial portal were ultimately based on the physical examination in the clinic preoperatively and confirmed again intraoperatively. As defined later, the key determination is the ability to precisely localize the ulnar nerve by palpation in the region of the planned anteromedial portal. Ulnar nerve localization at the planned portal site was considered to be (1) unequivocal, (2) equivocal, or (3) impossible (Fig 1). In group 1 ulnar nerve localization at the planned portal site was considered to be unequivocal if the nerve was palpable along its entire course in the transposed position (or along its entire course with the exception of the very proximal or distal portions) and there was no tubular structure or ulnar paresthesia with palpation
behind the epicondyle. In most cases the transposed nerve was also mobile so that it could be rolled back and forth under the skin and/or the patient had localized paresthesia in the ulnar nerve distribution in the hand when the nerve was rolled with some compression (like “hitting the funny bone”). In group 2 ulnar nerve localization at the planned portal site was considered to be equivocal if the nerve was palpable along only part of its course or if palpation at the planned portal site showed neither a distinct nor mobile nerve nor localizing paresthesia or if there was a tubular structure behind the medial epicondyle, which might have been the nerve. Finally, in group 3 ulnar nerve localization at the planned portal site was considered to be impossible if the nerve was not palpable anywhere in that region. Most commonly, this occurred in obese patients, whose thick layer of adipose tissue obscured the nerve. Portal Placement Based on Ulnar Nerve Localization In group 1, in which ulnar nerve localization at the planned portal site was unequivocal, the proximal anteromedial portal was established in the normal antegrade fashion with the following technique. If the nerve was mobile, it was rolled back and forth several times to confirm the location. Then, with the nerve rolled posteriorly and held there by a finger, the prox-
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FIGURE 2. Transposed ulnar nerve. In group 1, in which ulnar nerve localization at the planned portal site was unequivocal, the proximal anteromedial portal was established in the normal antegrade fashion with the following precaution. If the nerve was mobile, it was rolled back and forth several times to confirm the feel of doing so. Then, with the nerve rolled posteriorly and held there by a finger, the proximal anteromedial portal was established anterior to the nerve. If the nerve was not mobile, the proximal anteromedial portal was placed either anterior or posterior to the nerve, whichever offered the greatest clearance from the nerve and best line of approach to the joint.
imal anteromedial portal was established anterior to the nerve (Fig 2). If the nerve was not mobile, the proximal anteromedial portal was placed either anterior or posterior to the nerve, whichever offered the greatest clearance from the nerve and best line of approach to the joint. This course was almost always anterior to the nerve. A blunt-tip, pointed 4-mm switching stick was then used to penetrate the capsule and enter the joint. The arthroscope sheath was then gently passed down over the switching stick into the joint. In group 2, in which ulnar nerve localization at the planned portal site was equivocal, a 1-cm incision was made in the skin at the planned site of the proximal anteromedial portal. The location was either anterior or posterior to the nerve, whichever offered the great-
est clearance from the nerve and best line of approach to the joint. Blunt dissection (spreading longitudinally in parallel with the nerve) was then used to dissect past the nerve to the joint capsule without identification of the nerve. A blunt-tip, pointed 4-mm switching stick was then used to penetrate the capsule and enter the joint. The arthroscope sheath was then gently passed down over the switching stick into the joint. Because the edge of the sheath could catch the nerve, the sheath was advanced slowly and without force while rotating it back and forth (around the switching stick). Finally, in group 3, in which ulnar nerve localization at the planned portal site was impossible, a 2- to 4-cm skin incision was made at the planned site of the proximal anteromedial portal. The ulnar nerve was identified and the best line of approach to the joint determined. After incising through the dermis, the surgeon used blunt dissection down to the deep fascia. Digital palpation was used to locate the nerve, and then only sufficient longitudinal blunt dissection was used to confirm that the palpable structure thought to be the nerve was, indeed, the nerve. Blunt dissection past the nerve was followed by passage of a blunt-tip, pointed 4-mm switching stick down to the capsule under direct visualization while protecting the nerve. After penetration of the capsule, the arthroscope sheath was then passed down over the switching stick into the joint. Methods of Portal Placement Tried During Early Years During the learning curve involving the first few cases, other methods were used before the current decision-making algorithm was derived. In group 2, in which ulnar nerve localization at the planned portal site was equivocal, 2 patients had the proximal anteromedial portal established in a retrograde manner by use of a switching stick and the inside-out technique. This was later abandoned based on the reasoning that if the ulnar nerve was stuck in scar tissue, the insideout technique would not necessarily prevent a significant blunt injury to the nerve (or conceivably even disruption). In 3 cases (2 patients) in group 3, in whom ulnar nerve localization at the planned portal site was impossible, 2 anterolateral portals (anterolateral and proximal anterolateral) were used without any anteromedial portal. In those cases the nerve had been transposed in a submuscular manner and was not palpable. They were early in the series, when standard teaching
ANTEROMEDIAL ELBOW ARTHROSCOPY PORTALS was that a transposed nerve was a contraindication to use of anteromedial portals. For subsequent cases such as this, we chose to explore the nerve through a 2- to 4-cm incision as described previously and then create a proximal anteromedial portal. Another method used early in the series was insertion of a plastic cannula in the proximal anteromedial portal. The reasoning was that moving instruments in and out of a cannula would lessen the risk of harm to the nearby transposed ulnar nerve during instrument exchange. This was only done twice, because the cannula seemed to be more a hindrance than a help. The senior author has developed rapid portal-switching techniques that are safe and effective and that obviate the use of cannulas. Specific Considerations With Submuscular Transpositions The term “submuscular transposition” has been used to mean any procedure involving placement of the nerve under the common flexor-pronator musculature adjacent to the median nerve. Because of the unpredictability of knowing exactly where the nerve might be, and the fact that it might be adjacent to the anterior capsule, the senior author considered prior submuscular transposition of the ulnar nerve to be a relative contraindication to anterior capsulectomy. RESULTS Elbows With Prior Ulnar Nerve Transposition Of the 913 elbow arthroscopies performed during the 15-year study period, 59 met the inclusion criteria of having a subluxating or previously transposed ulnar nerve and requiring therapeutic anterior compartment surgery involving at least 2 portals. Of these, 28 elbows (cases) in 26 patients with a prior ulnar nerve transposition underwent therapeutic arthroscopic surgery. Of these cases, 7 had a prior submuscular transposition and 21 had subcutaneous transposition. During this same 15-year period, no patients with a prior ulnar nerve transposition were considered ineligible for arthroscopic surgery and therefore had an open procedure, based on the nerve having been transposed. At the time of surgery, the mean age was 39 years (range, 12 to 76 years). There were 21 male patients. The diagnosis was a post-traumatic contracture in 15 cases, primary osteoarthritis in 6, inflammatory arthritis in 2, and post-traumatic plica and/or loose bodies in 5. The mean number of elbow surgeries before the index procedure was 2 (range, 1 to 4).
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The indication for surgery was a contracture release in 23 cases and mechanical symptoms due to a snapping plica or loose bodies in 5. All of the patients had normal nerve function 3 days after surgery. At a mean follow-up of 20 months (range, 1 to 72 months), no patients showed neurologic symptoms. In 4 cases only a first postoperative evaluation 3 days after surgery was available for review. Each of these patients had normal nerve function right after surgery and at day 3 postoperatively. Normal nerve function was defined as full motor strength in the ulnar, median, and radial nerve distribution (extrinsic and intrinsic muscles); the ability to distinguish little touches at the tips of each of the 5 digits and in the first dorsal interosseous space with the eyes closed; and the subjective impression that the hand felt normal to the patient. During the arthroscopic procedure, the proximal anteromedial portal was used in 25 cases. In the remaining 3 cases, only 2 anterolateral portals were used. The details of the different techniques used to place the proximal anteromedial portal are reported in Fig 3. Two patients had a modification of the procedure early in the series when we were less confident as to how to manage the elbow after submuscular transposition of the nerve. In those 2 cases, 2 lateral portals were used with no medial portals, and in 1 case a partial anterior capsulectomy was performed in the other case of debridement. Elbows With Ulnar Nerve Subluxation Thirty-one elbows (cases) in thirty patients had ulnar nerve subluxation. The mean age was 30 years (range, 11 to 57 years). There were 26 male patients. The diagnosis was osteoarthritis in 9 cases, posttraumatic contracture in 5, post-traumatic plica associated with loose bodies or lateral epicondylitis in 4, loose bodies in 5, osteoid osteoma in 3, rheumatoid
FIGURE 3. Proximal anteromedial portal placement after ulnar nerve transposition.
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arthritis in 2, osteochondritis dissecans in 2, and posteromedial impingement in 1. Nine cases had had prior surgery not related to the ulnar nerve. Of these, 4 had open surgeries, 3 had arthroscopic surgeries, and 2 had both open and arthroscopic surgeries. Nineteen cases underwent an arthroscopic capsulectomy or capsulotomy. In all cases the proximal anteromedial portal was placed while the ulnar nerve was held in a reduced position. All of the patients were examined on the day of discharge and on day 3 or later postoperatively. The mean follow-up was 23 months (range, 1 to 108 months). Four patients did not return for later follow-up but had a normal neurologic examination after surgery and on day 3. No patients in this group had any direct operative injury to the ulnar nerve. In this group of patients with a subluxating ulnar nerve, a tardy ulnar neuropathy developed in 4 in the early postoperative period after a normal neurologic examination immediately after surgery. Each of these patients had a contracture release performed, followed by 3 days of continuous passive motion in the hospital with an indwelling continuous brachial plexus block anesthetic. After discontinuation of the block, the ulnar neuropathies were apparent on day 3 or day 4. Each patient showed both sensory and motor loss that was progressive and associated with progressive loss of motion in the elbow. They were treated by ulnar nerve decompression and subcutaneous transposition on days 4 to 8. One patient had recovered completely at 4 weeks’ follow-up, and one was almost normal (slight sensory impairment) at 4 months. One patient recovered completely within 2 years. One patient, during her last follow-up available (3 months), still had moderate ulnar weakness. Exploration of these ulnar nerves at the time of transposition failed to show any contusion or direct lesion to the nerve, including in the proximity of the proximal anteromedial portal. In all 4 cases compression of the ulnar nerve was observed at the cubital tunnel retinaculum. These patients had increases in extension, flexion, and total arc of motion. Preoperatively, extension was 43° (range, 40° to 45°), flexion was 118° (range, 110° to 125°), and the total arc of motion was 75° (range, 70° to 80°). Postoperatively, extension was 3° (range, 0° to 10°), flexion was 135° (range, 135° to 140°), and the total arc of motion was 132° (range, 125° to 140°). They gained a mean of 60° in the arc of motion (range, 55° to 70°), with flexion increasing from 118° to 138°, for a mean of 40° (range, 10° to 25°). None of them had undergone prophylactic ulnar nerve decompres-
sion at the time of contracture release. They were all managed by subcutaneous ulnar nerve transposition 4 to 8 days after the index surgery. An infection was diagnosed in 1 patient 3 weeks after an arthroscopic plica excision and open tennis elbow repair. Six months after irrigation and debridement, he was considered healed. Use of Second Anteromedial Portal The data presented previously all refer specifically to the use of the proximal anteromedial portal. It is preferred over the originally described anteromedial portal (located at the joint line), which penetrates the flexor-pronator tendon. The principal indication for the anteromedial portal is to place a second retractor into the anterior compartment of the elbow.21 A second anteromedial portal was used in 8 elbows. Of these 8 cases, 7 were patients with subluxating ulnar nerves. In only 1 patient with a prior transposition was the anteromedial portal used in addition to the proximal anteromedial portal. This patient was in group 1, in whom the nerve was able to be localized unequivocally throughout its course. Thus avoiding it during placement of a second portal was no more difficult than with the first portal. We considered the anteromedial portal (i.e., at the joint line) to be contraindicated in a patient with a submuscular transposition, because the nerve is obscured by the flexor-pronator origin, which must be penetrated to establish that portal. DISCUSSION Despite advances in elbow arthroscopy, there have been reports of neurologic injury of all 3 major nerves of the elbow.5-10 An important first step in safe elbow arthroscopy is to recognize the circumstances in which the risk of nerve injury is increased. The anatomic relation between portal sites and the nerves has been well documented.22-24 However, any condition that alters this normal relation theoretically increases the risk of nerve injury during portal placement or use. Although many authors have described previous ulnar nerve transposition as at least a relative contraindication to the use of anteromedial portals, there are no data in the literature documenting the risk of nerve injury in such circumstances.13-18 This study is the first that documents the safety of certain strategies permitting the use of the proximal anteromedial portal in a consecutive series of patients requiring therapeutic arthroscopic procedures in the anterior compart-
ANTEROMEDIAL ELBOW ARTHROSCOPY PORTALS ment of the elbow after prior ulnar nerve transposition. A similar strategy was successfully and safely used in patients with subluxating ulnar nerves. The strategy that was used to avoid injuring a transposed or subluxating ulnar nerve in this series of patients was rather simple. It was based entirely on the degree of certainty with which the nerve could be identified and localized before placement of the proximal anteromedial portal. If the location of the transposed ulnar nerve was unequivocal, we made a portal about 1 cm away from the nerve and avoided the nerve. If the location of the nerve was equivocal (i.e., we were fairly confident but not certain), we made the skin incision for the portal about 1 cm away from the nerve and then bluntly dissected down to the capsule, passing the nerve without identifying it. A pointed, blunt-tip switching stick was passed down the same path and used to penetrate the joint capsule. Over the switching stick, the arthroscope sheath was gently passed into the joint. Finally, if localization of the nerve was impossible, we made a 2- to 4-cm incision and identified the nerve before establishing the portal (otherwise as for the equivocal nerve). During the same 15-year period, 402 elbows underwent open capsular releases. However, in none of these cases was the decision to perform open surgery instead of arthroscopic surgery influenced by whether the ulnar nerve had been transposed previously or subluxated. Although we tried other techniques early in the series, this strategic approach became standard and reproducible with time. Before conceiving of this approach based on localizing the nerve, we tried using only 2 anterolateral portals in 3 cases (2 patients). However, we abandoned this technique because it limited our ability to achieve the goals of surgery. We also used an inside-out technique in 2 cases but abandoned that as well. Our concern was that if the nerve was embedded in scar tissue, it might not displace away from the switching stick being passed from inside out. That would potentially expose the nerve to risk of injury as well. We thought that gentle blunt dissection from outside in would be a safer way to pass by the nerve. Because we used the inside-out technique only twice, its safety cannot be derived from our data. Subluxation or dislocation of the ulnar nerve proved to be straightforward to manage. We simply reduced and held it behind the epicondyle while establishing or re-entering the anteromedial portals. We did not use magnetic resonance imaging and intraoperative ultrasound in any of the patients. Nor-
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mal nerves can be localized reliably with these techniques, but we were uncertain as to their reliability for the transposed nerve in the setting of anatomic distortion and scarring from prior surgery and possibly trauma. In addition, magnetic resonance imaging is performed with the elbow extended, whereas elbow arthroscopy is performed at about 90° of flexion. This change in position could theoretically alter anatomic relations around the nerve. Intraoperative ultrasound would probably be helpful but would be more cumbersome, time-consuming, and expensive than the approach used in our patients. It also requires an experienced operator, which many surgeons are not. Our recommendation for use of the proximal anteromedial portal applies to elbows in which the nerve has been transposed into either the subcutaneous or submuscular position. However, the traditional anteromedial portal (at the level of the joint) is probably unsafe in patients with submuscular transposition. In addition, the safety of arthroscopic capsulectomy after submuscular transposition is uncertain. Although the senior author has extensive experience with arthroscopic capsulectomy including arthroscopic nerve dissection, a transposed nerve may be scarred to surrounding structures and difficult to dissect free of them. This is in contrast to a native undissected nerve (such as the radial nerve, which also lies adjacent to the anterior capsule of the elbow). Thus, if the ulnar nerve is scarred to the anterior capsule, the nerve might be at greater risk of being damaged during arthroscopic capsulectomy. Until more experience is documented, such cases should be considered individually based on the experience of the surgeon. A limitation of this study is that 4 patients in the subluxation group had follow-up of only 3 days. Because ulnar nerve subluxation could possibly be a risk factor for tardy ulnar neuropathy postoperatively, it is possible that tardy ulnar neuropathy may have developed in those patients without our knowledge. If so, this would have increased the statistical likelihood of this being a risk factor for this complication. Tardy ulnar neuropathy after contracture release has been reported by Huffmann et al.25 The 4 patients in our series were typical of those affected by this complication, with a significant gain in motion, particularly flexion. In addition, this is a retrospective study in which the categorization of ulnar nerve location was applied retroactively. In other words, in the early part of the series, the algorithm itself had not been formulated and thus the categorization of patients was based on retrofitting their data to the algorithm presented.
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The proximal anteromedial portal can be used in a manner that is safe for patients who have had transposition of the ulnar nerve or whose nerve subluxates. Modifications to standard techniques are necessary, based on the certainty with which the ulnar nerve can be localized by palpation in the region of the planned portal. We conclude that neither elbow arthroscopy nor specifically the use of the proximal anteromedial portal is contraindicated in patients with prior transposition or subluxation of the ulnar nerve. The management of the nerve can be based on the degree of certainty with which the nerve can be localized by palpation in the region of the planned portal. Acknowledgment: The authors appreciate the input and assistance of John Eric Gee, M.D., in the preparation of this work.
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