3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1653
ORIGINAL RESEARCH
A Randomized Comparison of Proximal and Distal Ultrasound-Guided Adductor Canal Catheter Insertion Sites for Knee Arthroplasty Edward R. Mariano, MD, MAS, T. Edward Kim, MD, Michael J. Wagner, MD, Natasha Funck, MD, T. Kyle Harrison, MD, Tessa Walters, MD, Nicholas Giori, MD, PhD, Steven Woolson, MD, Toni Ganaway, BA, Steven K. Howard, MD Objectives—Proximal and distal (mid-thigh) ultrasound-guided continuous adductor canal block techniques have been described but not yet compared, and infusion benefits or side effects may be determined by catheter location. We hypothesized that proximal placement will result in faster onset of saphenous nerve anesthesia, without additional motor block, compared to a distal technique.
Received November 13, 2013, from the Departments of Anesthesiology, Perioperative and Pain Medicine (E.R.M., T.E.K., M.J.W., N.F., T.K.H., T.W., T.G., S.K.H.) and Orthopedic Surgery (N.G., S.W.), VA Palo Alto Health Care System, Palo Alto, California USA; and Stanford University School of Medicine, Stanford, California USA. Revision requested December 3, 2013. Revised manuscript accepted for publication December 18, 2013. We gratefully acknowledge the invaluable assistance of the entire operating and recovery room staff at the VA Palo Alto Health Care System, especially our regional anesthesia and acute pain medicine fellows, Brett Miller, MD, Justin Workman, MD, Genie Kim, MD, Jody Leng, MD, and Michael Rasmussen, MD. Dr Mariano has received unrestricted educational program funding paid to his institution fro m I-Flow/KimberlyClark (Lake Forest, CA) and B. Braun (Bethlehem, PA). These companies had no input into any aspect of the study design and implementation; data collection, analysis, and interpretation; or manuscript preparation. Address correspondence to Edward R. Mariano, MD, MAS, Anesthesiology and Perioperative Care Service, VA Palo Alto Health Care System, 3801 Miranda Ave, 112A, Palo Alto, CA 94304 USA. E-mail: [email protected] Abbreviations
IV, intravenous doi:10.7863/ultra.33.9.1653
Methods—Preoperatively, patients receiving an ultrasound-guided nonstimulating adductor canal catheter for knee arthroplasty were randomly assigned to either proximal or distal insertion. A local anesthetic bolus was administered via the catheter after successful placement. The primary outcome was the time to achieve complete sensory anesthesia in the saphenous nerve distribution. Secondary outcomes included procedural time, procedure-related pain and complications, postoperative pain, opioid consumption, and motor weakness. Results—Proximal insertion (n = 23) took a median (10th–90th percentiles) of 12.0 (3.0–21.0) minutes versus 6.0 (3.0–21.0) minutes for distal insertion (n = 21; P = .106) to anesthetize the medial calf. Only 10 of 25 (40%) and 10 of 24 (42%) patients in the proximal and distal groups, respectively, developed anesthesia at both the medial calf and top of the patella (P = .978). Bolus-induced motor weakness occurred in 19 of 25 (76%) and 16 of 24 (67%) patients in the proximal and distal groups (P = .529). Ten of 24 patients (42%) in the distal group required intravenous morphine postoperatively, compared to 2 of 24 (8%) in the proximal group (P = .008), but there were no differences in other secondary outcomes. Conclusions—Continuous adductor canal blocks can be performed reliably at both proximal and distal locations. The proximal approach may offer minor analgesic and logistic advantages without an increase in motor block. Key Words—continuous adductor canal block; knee arthroplasty; musculoskeletal ultrasound; perineural catheter; ultrasound-guided regional anesthesia
F
or major knee surgery, including total knee arthroplasty, a continuous adductor canal block with perineural catheter insertion may provide effective postoperative analgesia.1–4 In addition, an adductor canal block may preserve quadriceps strength to a greater extent than a femoral nerve block.3,5,6 Retrospective cohort studies suggest that this strength advantage may result in improved early ambulatory ability after total knee arthroplasty.7,8
©2014 by the American Institute of Ultrasound in Medicine | J Ultrasound Med 2014; 33:1653–1662 | 0278-4297 | www.aium.org
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1654
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
There is some controversy regarding the optimal location for adductor canal catheter placement. The mid-thigh catheter insertion site has been previously described,1–5,9 but this location is invariably within the planned sterile surgical field. Alternatively, a more proximal approach has been described,10 also referred to as the “selective femoral nerve block.” This technique targets the adductor canal at its entrance just distal to the apex of the femoral triangle and has been shown to spare the motor branches to the quadriceps in a cadaver study.10 A proximal technique offers the potential advantages of faster block onset from more cephalad spread, as described for femoral nerve catheters,11 and a catheter location further displaced from the surgical field but still runs the theoretical risk of quadriceps weakness if the main femoral nerve becomes anesthetized.12 To date, these two approaches have not been compared head to head; therefore, any potential infusion benefits or side effects attributable to catheter location remain unknown. We designed this study to test the hypothesis that proximal placement will result in faster onset of saphenous nerve anesthesia, without additional motor block, compared to a distal (mid-thigh) technique.
Materials and Methods This study was approved by the Institutional Review Board of Stanford University and the Veterans Affairs Research and Development Committee of the VA Palo Alto Health Care System and prospectively registered at http://www.clinicaltrials.gov (NCT01459523). Adults (>18 years old) scheduled for unilateral knee arthroplasty with an adductor canal perineural catheter planned for postoperative analgesia were considered for inclusion. Patients unable to understand the study protocol or care for the infusion pump/catheter system or with any known contraindication to study medications or regional anesthesia, insulin-dependent diabetes mellitus, neuropathy of any etiology in the affected extremity, hepatic or renal failure, any additional surgical site outside the limb intended for catheter placement, chronic opioid use or active illicit substance abuse, pregnancy, or an inability to communicate with the investigators and hospital staff were excluded. Protocol After providing written informed consent, patients were randomly assigned to one of two treatment groups, proximal (selective femoral) or distal (mid-thigh), using sealed envelopes containing group assignments based on a computergenerated randomization sequence (http://www. randomizer.org). All procedures were performed by an
1654
attending regional anesthesiologist experienced in both placement techniques or by a regional anesthesiology and acute pain medicine fellow directly supervised by the attending anesthesiologist. Patients and the research assistant performing assessments were blinded to group assignment. Each patient’s ability to perform a straight leg raise in the supine position, defined as raising the heel off the bed at least 6 in (15 cm) with the leg extended and hip flexed,13 on the surgical and nonsurgical side was assessed at baseline. After peripheral intravenous (IV) catheter insertion and positioning, standard noninvasive monitors and oxygen via a face mask or nasal cannulas were applied. Patients received IV midazolam and fentanyl titrated to their comfort but maintaining verbal responsiveness. The planned procedural area was sterilely cleansed with chlorhexidine gluconate and isopropyl alcohol (ChloraPrep One-Step; CareFusion, Leawood, KS), and a clear fenestrated sterile drape was applied. The ultrasound machine (M-Turbo HFL38; SonoSite, Inc, Bothell, WA) with a 13–6-MHz linear array ultrasound transducer placed in a sterile sleeve was prepared for use. Proximal Technique Patients randomized to the proximal group underwent perineural catheter insertion using a slight modification of a method described previously.10 After the femoral nerve was identified in the short axis near the inguinal crease, the ultrasound transducer was moved caudally beyond the apex of the femoral triangle and distal to the bifurcation of the femoral artery, where the medial border of the sartorius muscle first covers the superficial femoral artery at the entry to the adductor canal (Figure 1). A local anesthetic (1% lidocaine) skin wheal was raised 1 cm lateral to the transducer, and the same local anesthetic solution was deposited along the planned trajectory of the catheter placement needle. An uninsulated, 8.9-cm, 17-gauge Tuohy-tip needle (Arrow FlexTip Plus; Teleflex Medical, Research Triangle Park, NC) was inserted through the skin wheal and directed in-plane beneath the transducer in a medial direction toward the target nerve until the needle tip passed through the sartorius muscle and entered the adductor canal lateral to the target nerve and superficial femoral artery. An initial injection of 5 mL (5% dextrose in water) was made via the placement needle, and then a 19-gauge flexible epidural-type catheter (Arrow FlexTip Plus) was inserted through the length of the needle and advanced 1 to 3 cm beyond the needle tip posterior to the nerve under direct ultrasound visualization with an assistant stabilizing the transducer (Figure 2). Once the catheter was placed, the needle was withdrawn over the catheter while inserting
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1655
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
additional catheter length into the sartorius muscle and overlying subcutaneous tissue layer, and the catheter tip position was assessed by injecting 0.5 mL of air via the catheter under ultrasound imaging.14 After negative aspiration for blood, 15 mL of an anesthetic solution (2% mepivacaine with epinephrine, 2.5 μg/mL) was injected incrementally via the catheter. Distal Technique Patients randomized to the distal technique underwent adductor canal perineural catheter insertion using a method
Figure 1. Unembalmed cadaver dissection illustrating the course of the saphenous nerve and the sites of perineural catheter insertion for this study. X indicates sartorius muscle (displaced medially to expose the saphenous nerve); asterisk, saphenous nerve; white arrow, approximate catheter insertion site for the proximal group; and black arrow, approximate catheter insertion site for the distal (mid-thigh) group.
described previously.4 After the saphenous nerve was identified in the short axis, deep to the sartorius muscle and lateral to the superficial femoral artery and approximately halfway between the anterior superior iliac spine and the patella, catheter insertion proceeded stepwise in a similar manner as in the proximal group. The perineural catheter was advanced 1 to 3 cm beyond the needle tip posterior to the nerve under direct ultrasound visualization with an assistant stabilizing the transducer (Figure 3). Catheter placement was confirmed and injectate delivered in the same manner as in the proximal group. Figure 2. Short-axis image of the saphenous nerve in the adductor canal during proximal placement of a perineural catheter. A indicates superficial femoral artery; N, saphenous nerve; S, sartorius muscle; asterisk, distal end of the needle; and arrowheads, distal end of the catheter.
Figure 3. Short-axis image of the saphenous nerve in the adductor canal during distal (mid-thigh) placement of a perineural catheter. Abbreviations and symbols are as in Figure 2.
J Ultrasound Med 2014; 33:1653–1662
1655
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1656
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
All catheters were tunneled subcutaneously per protocol in a cephalad and lateral direction toward the anterior
superior iliac spine using the placement needle and its stylet, as described previously (Figure 4).15 The catheter
Figure 4. Subcutaneous tunneling technique. A, The stylet is inserted into the same entry hole from which the catheter emerges. B, The stylet is advanced subcutaneously in a cephalad and lateral direction toward the anterior superior iliac spine. C, The placement needle is inserted over the tip of the stylet. D, The placement needle is advanced along the same subcutaneous track using the stylet as a guide. E, The proximal end of the catheter is inserted into the tip of the placement needle after the stylet is removed. F, The placement needle is withdrawn after the catheter emerges from the hub, and the catheter is pulled until the remaining catheter loop is buried within the subcutaneous layer.
1656
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1657
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
was secured with clear occlusive dressings and an anchoring device (StatLock; Bard Medical, Covington, GA), and the catheter insertion site was covered with a blanket to obscure the catheter location before assessment by the research assistant to maintain blinding. If a catheter was not placed successfully per protocol (within 30 minutes), the patient was removed from the study but was still eligible to receive a nerve block or perineural catheter placed by the patient’s regional anesthesiologist using any technique at his or her discretion. Primary Outcome The onset time (minutes) for complete sensory anesthesia was the primary outcome and was measured after completion of the mepivacaine bolus. Sensory assessments were performed using pinprick sensation (0, no change from baseline; 1, diminished pinprick sensation; 2, no pinprick sensation)16,17 in the medial calf proximal to the medial malleolus and the top of the patella by a blinded research assistant every 3 minutes for up to 30 minutes, with a score of 2 in the medial calf distribution considered complete sensory anesthesia of the saphenous nerve. Patients without anesthetic onset at 30 minutes were considered to have had unsuccessful catheter placements and were withdrawn from further study; catheters were retained and reassessed postoperatively for possible replacement. Secondary Outcomes During the procedure, the following measurements were recorded: catheter placement time (minutes) beginning when the ultrasound transducer first touched the patient’s skin and ending when the placement needle was removed after catheter insertion, number of needle passes (each withdrawal of the placement needle >1 cm plus redirection counting as an additional pass), amount of IV fentanyl (micrograms) administered, and number of vascular punctures. Immediately after catheter insertion, patients were asked to rate their procedure-related discomfort on a numeric rating scale of 0 to 10 (0, no discomfort; 10, worst discomfort imaginable). Motor assessments of the quadriceps were performed by voluntary leg extension against resistance with the patient in the supine position and the hip passively flexed (0, no change from baseline; 1, diminished active contraction; 2, no active contraction) by a blinded research assistant every 3 minutes for up to 30 minutes, with a score of 2 considered a complete motor block. All patients received general anesthesia, although the intraoperative anesthetic technique was not standardized. At the conclusion of surgery, all patients received periarticular injections of 0.2% ropivacaine (150 mL) and
J Ultrasound Med 2014; 33:1653–1662
epinephrine (2.5 μg/mL) with ketorolac (30 mg) divided equally within the posterior capsule, retinacular layer, and subcutaneous tissue per institutional protocol.18,19 The amount of IV opioid (eg, micrograms of fentanyl or milligrams of morphine) administered intraoperatively and in the postanesthesia care unit was recorded. Each perineural catheter was attached to a portable infusion device (ON-Q C-bloc with ONDEMAND; I-Flow Corporation, Lake Forest, CA) set to deliver an infusion of 0.2% ropivacaine (basal rate of 6 mL/h; patient-controlled bolus of 5 mL; and lockout interval of 30 minutes). Patients were prescribed scheduled oxycodone, acetaminophen, and diclofenac plus additional oral oxycodone and IV morphine for breakthrough postoperative pain inadequately treated with the perineural ropivacaine infusion and bolus. None of the patients were prescribed IV opioid patient-controlled analgesia, per our institutional clinical analgesic protocol.7 On postoperative day 1, patients were evaluated in person by a blinded research assistant to collect information regarding average and worst postsurgical pain (numeric rating scale of 0–10), opioids consumed (milligrams of oxycodone and/or IV morphine), number of sleep disturbances, satisfaction with pain control using a Likert scale (0, not at all satisfied; 10, extremely satisfied), leakage of fluid from the catheter site, ability to perform the straight leg raise, and a subjective rating of numbness (0, normal sensation; 10, completely insensate). After completion of study-related procedures, clinical regional anesthesiology and perioperative analgesia staff continued to follow all patients daily for the duration of their perineural infusions. Sample Size Estimate The onset time for complete sensory anesthesia in the distribution of the target nerve was the primary outcome. Using published onset times for ultrasound-guided femoral perineural catheters by a short-axis, in-plane technique with a through-the-catheter bolus of mepivacaine,11 2-sided type I error protection of .05, and power of 80%, 21 patients in each treatment arm were required to detect a difference between treatment group means of 5 minutes, which was considered relevant to our clinical practice and would clearly demonstrate an advantage of one catheter insertion location over the other. We enrolled 25 patients per group to account for unanticipated patient dropout or protocol violations. Statistical Analysis Statistical analysis was performed with NCSS-PASS statistical software (NCSS, Kaysville, UT) by an investigator blinded to study group identity. Normality of distribution
1657
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1658
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
was determined for all scale variables. For normally distributed data, single comparisons were performed using the Student t test; for continuous data in distributions other than normal, the Mann-Whitney U test was used. The z test or Barnard exact test (n < 5 in any field) were used for comparisons of categorical data. Intent to treat was applied for all analyses, and 2-sided P < .05 was considered statistically significant for the primary outcome. Statistically significant findings for secondary outcomes should be interpreted as suggestive, requiring confirmation in a prospective trial before being considered definitive.20
Results Seventy-seven patients were assessed for eligibility; 17 patients did not meet the criteria for enrollment; 2 declined to participate; 1 was interested but not enrolled due to cancellation of surgery; and 7 were not enrolled because of time constraints. Fifty patients were enrolled and randomly assigned to one of the two study groups. Demographic and morphometric characteristics were similar between groups (Table 1). At baseline, 92% (23 of 25) and 83% (20 of 24) patients in the proximal and distal groups, respectively, were able to perform a straight leg raise (P = .528). Median (10th–90th percentiles) for elevation of the heel on the surgical side during the straight leg raise before surgery was 46 (28–48) cm for the proximal group (n = 23) versus 48 (31–48) cm for the distal group (n = 20; P = .556). All patients in the proximal group (n = 25) underwent successful catheter insertion per protocol. In the distal group (n = 25), 1 patient (body mass index, 47 kg/m2) failed catheter placement per protocol due to inadvertent dislodgement after tunneling and was withdrawn from the study, but he did receive a perineural catheter for postoperative analgesia at the regional anesthesiologist’s discretion. Table 1. Morphometric Data and Procedural Information Parameter Age, y Female/male, n ASA physical status Height, cm Weight, kg Body mass index, kg/m2 Attending/fellow placement, n Knee arthroplasty procedure, n Primary unicompartmental Primary total
Proximal (n = 25)
Distal (n = 24)
66 (59–75) 0/25 3 (2–3) 177 (170–185) 102 (84–136) 33 (28–41) 2/23
65 (57–71) 0/24 3 (2–3) 178 (168–185) 97 (76–128) 30 (25–39) 1/23
1 24
1 23
Values are reported as median (10th–90th percentiles) where applicable. ASA indicates American Society of Anesthesiologists.
1658
One patient in the proximal group did not provide postoperative follow-up data because surgery was canceled after anesthetic induction due to traumatic urinary catheter insertion. Primary Outcome Ninety-two percent (23 of 25) and 88% (21 of 24) of patients in the proximal and distal groups, respectively, achieved complete sensory anesthesia within 30 minutes (P = .707); the 5 patients who did not were found to have saphenous nerve anesthesia postoperatively, and their catheters were retained. Proximal insertion (n = 23) took a median (10th–90th percentiles) of 12.0 (3.0–21.0) minutes versus 6.0 (3.0–21.0) minutes for distal insertion (n = 21; P = .106) to anesthetize the medial calf. Only 10 of 25 (40%) and 10 of 24 (42%) patients in the proximal and distal groups developed anesthesia at both the medial calf and top of the patella (P = .978). Secondary Outcomes Proximal catheter placement procedures took 6.0 (4.0–8.6) minutes to perform compared to 6.0 (4.0–8.7) for distal (P = .808). Any bolus-induced motor weakness, partial or complete, within 30 minutes occurred in 19 of 25 (76%) and 16 of 24 (67%) patients in the proximal and distal groups, respectively (P = .529). There were no vascular punctures in either group and no differences in other procedure-related secondary outcomes (Table 2). Combined intraoperative and postanesthesia care unit opioid consumption was similar: 275 (200–380) versus 250 (150–400) μg of IV fentanyl (proximal and distal, respectively; P = .372) and 5.0 (0.0–11.2) versus 2.5 (0.0–10.0) mg of IV morphine (proximal and distal; P = .302). No catheters were inadvertently dislodged overnight in either group. In the first 24 hours after surgery, more patients in the distal group, 10 of 24 (42%), required IV morphine compared to 2 of 24 (8%) in the proximal group (P = .008). Table 2. Secondary Outcomes Related to Perineural Catheter Placement Parameter Needle passes, n Fentanyl, μg Procedural pain, NRS 0–10 No motor block, n Partial motor block, n Complete motor block, n
Proximal (n = 25)
Distal (n = 24)
P
1 (1–1) 50 (35–100) 1 (0–4) 6 9 10
1 (1–1) 50 (50–100) 2 (0–3) 8 9 7
.977 .274 .838 .529 .996 .529
Values are reported as median (10th–90th percentiles) where applicable. NRS indicates numeric rating scale.
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1659
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
The distal group required more IV morphine for breakthrough pain: 0.0 (0.0–7.4) versus 0.0 (0.0–0.0) mg in the proximal group (P = .009), but total opioid consumption (milligram of morphine equivalents) was similar: 23.3 (11.0–41.9) versus 23.3 (14.9–48.3) mg for the proximal and distal groups (P = .884). On postoperative day 1, 58% (14 of 24) and 54% (13 of 24) of patients in the proximal and distal groups were able to perform a straight leg raise (P = .873). Elevation of the heel on the surgical side during the straight leg raise was 46 (20–48) cm for the proximal group (n = 14) versus 38 (16–48) cm for the distal group (n = 13; P = .306). There were no differences in other postoperative day 1 secondary outcomes (Table 3). One patient, who was assigned to the distal group according to the computer-generated randomization sequence, inadvertently received a catheter placement in the proximal position; this error was not detected until after surgery and completion of data collection. The patient’s data were included in the distal group for analyses according to intent to treat. Inclusion of the patient in the proximal group based on actual treatment did not affect the results of the primary outcome (12.0 [3.0–21.0] versus 6.0 [3.0–21.9] minutes for proximal and distal, respectively; P = .108) or other secondary outcome analyses. There were no other protocol violations or adverse events related to the study procedures.
Discussion Continuous adductor canal blocks can be performed reliably at both proximal and distal locations, although a greater proportion of patients who receive proximal catheters are IV morphine-free for the first 24 hours after surgery. There is no difference in onset time for sensory anesthesia in the saphenous distribution below the knee, and less than half of patients in both groups have sensory anesthesia to the top of the patella. Bolus-induced motor weakness of
Table 3. Secondary Outcomes on Postoperative Day 1 Parameter Fluid leakage at site, n Numbness, Likert 0–10 Average pain, NRS 0–10 Worst pain, NRS 0–10 Awakenings from pain, n Satisfaction, Likert 0–10
Proximal (n = 24)
Distal (n = 24)
P
2 0.0 (0.0–2.7) 3.5 (0.1–6.0) 7.0 (2.6–10.0) 0.0 (0.0–2.0) 10.0 (8.3–10.0)
1 0.0 (0.0–4.7) 5.0 (1.0–8.0) 7.5 (0.3–10.0) 0.5 (0.0–10) 10.0 (8.0–10.0)
.596 .298 .121 .966 .079 .337
Values are reported as median (10th–90th percentiles) where applicable. NRS indicates numeric rating scale.
J Ultrasound Med 2014; 33:1653–1662
the quadriceps muscle can be detected in most patients in both groups, and nearly half of patients are unable to perform the straight leg raise on the day after surgery, with no difference between groups. Quadriceps Weakness and Peripheral Nerve Blocks Nerve blocks of the lumbar plexus,21 particularly femoral nerve blocks,12 have been shown to decrease quadriceps strength through local anesthetic-induced conduction blockade of motor nerves. In recent years, a great deal of negative attention has been cast on the potential role of peripheral nerve blocks in increasing the fall risk for patients undergoing total joint arthroplasty.22,23 Although debate continues, and new data suggest no association,24 many hospitals and anesthesiology practices that may not have comprehensive multicomponent fall prevention programs in place25 may be searching for an alternative to replace femoral nerve blocks within their pain management protocols for total knee arthroplasty. Current local anesthetic medications are nonselective and cannot pharmacologically choose to spare motor nerves versus sensory nerves. Therefore, the potential to select anatomic sites, such as the adductor canal,4,10 that may be less likely to expose motor nerves to a local anesthetic solution seems particularly attractive. Human volunteer studies have shown that adductor canal blocks spare quadriceps motor strength to a greater degree than femoral nerve blocks,5,6 and this quadriceps strength advantage may also occur in the clinical setting after total knee arthroplasty.3 However, ambulation advantages favoring adductor canal blocks reported by retrospective cohort studies7,8 have yet to be reproduced by randomized clinical trials. This study demonstrates that bolus-induced motor weakness of the quadriceps does occur after injecting a local anesthetic via an adductor canal catheter placed in either the proximal or distal (mid-thigh) location and may be attributable to cephalad spread of the local anesthetic to the main femoral nerve in a patient population with preexisting quadriceps weakness and diminished preoperative function, although anesthetizing the nerve to the vastus medialis may also be partially responsible. In a cadaver study and case series reported by Ishiguro et al,10 proximal pressure during dye and local anesthetic injection, respectively, was reported to decrease the likelihood of cephalad solution spread. We elected not to perform this maneuver, since it is not routinely part of our ultrasound-guided perineural catheter insertion technique for patients undergoing total knee arthroplasty11,26; this maneuver is not included in the distal approach; and there is no anatomic barrier between the femoral triangle and adductor canal to
1659
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1660
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
prevent late spread of an injectate solution.10 Our incidence of bolus-induced quadriceps muscle weakness does caution against the use of high-dose longer-acting local anesthetic solutions (eg, ropivacaine and bupivacaine) when patients are expected to bear weight on the operated extremity shortly after surgery. Previous studies using the mid-thigh approach have reported using a larger-volume initial bolus (30 mL) with 15-mL intermittent boluses every 6 hours postoperatively.4,9 Although the optimal local anesthetic regimen for adductor canal catheters is not known, a basal-bolus7 or basal rate-only3 regimen may have theoretical advantages in avoiding cephalad spread of the local anesthetic over a bolus-only regimen given the results of this study.1 Furthermore, our data showing that nearly half of patients cannot perform the straight leg raise on postoperative day 1 are consistent with a study by Jaeger et al,3 in which the median strength of patients receiving adductor canal catheters was 52% of baseline. Although patients with adductor canal blocks may have greater preservation of quadriceps strength compared to patients with femoral nerve blocks,3 quadriceps dysfunction after total knee arthroplasty can continue to be expected despite the use of an adductor canal block due to a variety of factors, such as preexisting weakness, surgical trauma, and age-related limitations in recovery of function even when a block is not performed at all.27 The risk of an inpatient fall in patients undergoing joint arthroplasty is multifactorial, with known contributors including advanced age, revision surgery, male sex, and increased comorbidity burden,28 and the occurrence of an inpatient fall may still occur in the presence of an adductor canal catheter. Regardless of the regional analgesic technique, all patients who undergo total knee arthroplasty should be considered at risk for an inpatient fall, and continued emphasis on multidisciplinary fall prevention is warranted. Catheter Tip Location and Onset Time To our knowledge, this study was the first to compare the efficacy of one site for adductor canal perineural catheter insertion to another. Although previous studies suggest that adductor canal catheters may offer analgesic benefits to patients after total knee arthroplasty,1–4 the optimal site for placement has remained unknown; furthermore, the distal (mid-thigh) approach may dissuade preoperative placement in clinical practice due to the location within the planned sterile surgical field. We sought to compare this approach to a more proximal technique10 to identify any potential advantages and/or disadvantages of each method. Since current regional anesthesia catheters are dif-
1660
ficult to visualize with ultrasound,29,30 requiring alternative strategies to infer the tip location,31,32 we chose the onset time for sensory anesthesia in the saphenous distribution as the surrogate outcome for catheter placement accuracy, as performed in previous studies.33–35 We chose a 5-minute difference as clinically relevant in the setting of a busy orthopedic surgery practice in which catheter placement success must be evaluated efficiently, and timely anesthetic onset before the start of surgery provides the patient and the anesthesiologist with confidence that the perineural catheter will be effective for analgesia in the postoperative period. This study did not show a statistically significant difference in onset time despite a 6-minute difference in the median onset time between groups; this result still may be attributable to a type II error, since the sample size was calculated on the basis of 80% power (β = .2), and we can speculate that a larger sample size may have shown a different result. However, we believe that a clearly superior catheter location should have shown a consistent advantage in terms of local anesthetic bolus distribution and sensory onset time within our calculated sample size. Interestingly, less than half of the patients in both groups developed sensory anesthesia to the top of the patella after the initial bolus, which indicates that the actual total knee arthroplasty incision may be incompletely anesthetized. Although local infiltration analgesia may complement adductor canal blocks in a multimodal analgesic protocol, it does not routinely last beyond 12 hours.36 A greater number of patients in the distal adductor canal catheter group did require IV morphine in the first 24 hours after surgery compared to the proximal group, suggesting perhaps that a more proximally placed catheter provides an analgesic advantage. However, there was no difference in total opioid consumption (milligram of morphine equivalents) between groups overall, and these secondary outcome findings require confirmation in a larger follow-up clinical trial. Catheter Placement Time There was no difference in catheter insertion times between the two techniques. For the purpose of measuring and comparing procedural times in this study, since both techniques used the same equipment, including ultrasound, we did not include the time required to prepare equipment, position and sedate the patient, sterilize and drape the procedural field and ultrasound equipment, perform the preprocedure timeout, and subcutaneously tunnel and secure the catheter after placement, similar to previous studies.26,37,38 We acknowledge that all of these steps can be expected to add to the total procedural time.
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1661
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
However, although we elected to subcutaneously tunnel all study catheters for the purpose of standardization per protocol, we believe that the location of the proximal approach (Figure 1) may not require further tunneling, since the catheter insertion site is already displaced cephalad from the planned surgical field. We speculate that eliminating the need to tunnel proximally inserted adductor canal catheters will decrease the total time required to perform this approach. In addition, the proximity in location and similarity in technique to the short-axis, in-plane femoral perineural catheter technique11,26 may facilitate adoption of adductor canal catheters for anesthesiology practices that wish to do so. Procedural efficiency in regional anesthesia on the day of surgery remains an important influencing factor for surgeons to recommend these effective analgesic techniques to their patients.39
References 1.
2.
3.
4.
5.
Study Limitations This study was not designed to compare adductor canal to femoral perineural catheters. For those anesthesiology practices that are interested in adopting adductor canal perineural catheters into their multimodal analgesic protocol for patients undergoing total knee arthroplasty, this study attempts to provide useful information regarding the optimal site for placement. The main limitation in this study design was that it was not truly double or triple blinded. The patients and the outcome assessor were blinded, and statistical analyses were performed before revealing group identity, but the regional anesthesiologists performing the study procedures were not blinded. In addition, the sample size for this study was small, increasing the likelihood of a type II error, and the intraoperative anesthetic protocol was not standardized. Generalizability of the study results is limited to practices using similar techniques and equipment as those used in this study; however, the equipment used was identical to that used in previously published studies.11,26 The use of other acceptable ultrasound-guided perineural catheter insertion techniques and equipment40–42 may produce different results.
6.
7.
8.
9.
10.
11.
12.
Conclusions In summary, ultrasound-guided adductor canal perineural catheter placement may be reliably performed in both proximal and distal locations. Bolus-induced quadriceps weakness can occur with both techniques, and postoperative quadriceps weakness remains common despite the use of adductor canal catheters. A more proximal approach may offer minor analgesic and logistic advantages without an increase in motor block, but these results require further confirmation.
J Ultrasound Med 2014; 33:1653–1662
13.
14.
15.
Andersen HL, Gyrn J, Moller L, Christensen B, Zaric D. Continuous saphenous nerve block as supplement to single-dose local infiltration analgesia for postoperative pain management after total knee arthroplasty. Reg Anesth Pain Med 2013; 38:106–111. Jaeger P, Grevstad U, Henningsen MH, Gottschau B, Mathiesen O, Dahl JB. Effect of adductor-canal-blockade on established, severe post-operative pain after total knee arthroplasty: a randomised study. Acta Anaesthesiol Scand 2012; 56:1013–1019. Jaeger P, Zaric D, Fomsgaard JS, et al. Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty: a randomized, double-blind study. Reg Anesth Pain Med 2013; 38:526–532. Lund J, Jenstrup MT, Jaeger P, Sorensen AM, Dahl JB. Continuous adductor-canal-blockade for adjuvant post-operative analgesia after major knee surgery: preliminary results. Acta Anaesthesiol Scand 2011; 55:14–19. Jaeger P, Nielsen ZJ, Henningsen MH, Hilsted KL, Mathiesen O, Dahl JB. Adductor canal block versus femoral nerve block and quadriceps strength: a randomized, double-blind, placebo-controlled, crossover study in healthy volunteers. Anesthesiology 2013; 118:409–415. Kwofie MK, Shastri UD, Gadsden JC, et al. The effects of ultrasoundguided adductor canal block versus femoral nerve block on quadriceps strength and fall risk: a blinded, randomized trial of volunteers. Reg Anesth Pain Med 2013; 38:321–325. Mudumbai SC, Kim TE, Howard SK, et al. Continuous adductor canal blocks are superior to continuous femoral nerve blocks in promoting early ambulation after TKA. Clin Orthop Relat Res 2014; 472:1377–1383. Perlas A, Kirkham KR, Billing R, et al. The impact of analgesic modality on early ambulation following total knee arthroplasty. Reg Anesth Pain Med 2013; 38:334–339. Jenstrup MT, Jaeger P, Lund J, et al. Effects of adductor-canal-blockade on pain and ambulation after total knee arthroplasty: a randomized study. Acta Anaesthesiol Scand 2012; 56:357–364. Ishiguro S, Yokochi A, Yoshioka K, et al. Technical communication: anatomy and clinical implications of ultrasound-guided selective femoral nerve block. Anesth Analg 2012; 115:1467–1470. Mariano ER, Kim TE, Funck N, et al. A randomized comparison of longand short-axis imaging for in-plane ultrasound-guided femoral perineural catheter insertion. J Ultrasound Med 2013; 32:149–156. Charous MT, Madison SJ, Suresh PJ, et al. Continuous femoral nerve blocks: varying local anesthetic delivery method (bolus versus basal) to minimize quadriceps motor block while maintaining sensory block. Anesthesiology 2011; 115:774–781. Walter F, Haynes MB, Markel DC. A randomized prospective study evaluating the effect of patellar eversion on the early functional outcomes in primary total knee arthroplasty. J Arthroplasty 2007; 22:509–514. Kan JM, Harrison TK, Kim TE, Howard SK, Kou A, Mariano ER. An in vitro study to evaluate the utility of the “air test” to infer perineural catheter tip location. J Ultrasound Med 2013; 32:529–533. Boezaart AP. Continuous interscalene block for ambulatory shoulder surgery. Best Pract Res Clin Anaesthesiol 2002; 16:295–310. 1661
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1662
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
16. Buys MJ, Arndt CD, Vagh F, Hoard A, Gerstein N. Ultrasound-guided sciatic nerve block in the popliteal fossa using a lateral approach: onset time comparing separate tibial and common peroneal nerve injections versus injecting proximal to the bifurcation. Anesth Analg 2010; 110:635–637. 17. Cuvillon P, Nouvellon E, Ripart J, et al. A comparison of the pharmacodynamics and pharmacokinetics of bupivacaine, ropivacaine (with epinephrine) and their equal volume mixtures with lidocaine used for femoral and sciatic nerve blocks: a double-blind randomized study. Anesth Analg 2009; 108:641–649. 18. Essving P, Axelsson K, Aberg E, Spannar H, Gupta A, Lundin A. Local infiltration analgesia versus intrathecal morphine for postoperative pain management after total knee arthroplasty: a randomized controlled trial. Anesth Analg 2011; 113:926–933. 19. Tripuraneni KR, Woolson ST, Giori NJ. Local infiltration analgesia in TKA patients reduces length of stay and postoperative pain scores. Orthopedics 2011; 34:173. 20. Mariano ER, Ilfeld BM, Neal JM. “Going fishing”: the practice of reporting secondary outcomes as separate studies. Reg Anesth Pain Med 2007; 32:183–185. 21. Ilfeld BM, Moeller LK, Mariano ER, et al. Continuous peripheral nerve blocks: is local anesthetic dose the only factor, or do concentration and volume influence infusion effects as well? Anesthesiology 2010; 112:347–354. 22. Feibel RJ, Dervin GF, Kim PR, Beaule PE. Major complications associated with femoral nerve catheters for knee arthroplasty: a word of caution. J Arthroplasty 2009; 24:132–137. 23. Ilfeld BM, Duke KB, Donohue MC. The association between lower extremity continuous peripheral nerve blocks and patient falls after knee and hip arthroplasty. Anesth Analg 2010; 111:1552–1524. 24. Memtsoudis SG, Danninger T, Rasul R, et al. Inpatient falls after total knee arthroplasty: the role of anesthesia type and peripheral nerve blocks. Anesthesiology 2014; 120:551–563. 25. Miake-Lye IM, Hempel S, Ganz DA, Shekelle PG. Inpatient fall prevention programs as a patient safety strategy: a systematic review. Ann Intern Med 2013; 158:390–396. 26. Mariano ER, Loland VJ, Sandhu NS, et al. Ultrasound guidance versus electrical stimulation for femoral perineural catheter insertion. J Ultrasound Med 2009; 28:1453–1460. 27. Stevens-Lapsley JE, Balter JE, Kohrt WM, Eckhoff DG. Quadriceps and hamstrings muscle dysfunction after total knee arthroplasty. Clin Orthop Relat Res 2010; 468:2460–2468. 28. Memtsoudis SG, Dy CJ, Ma Y, Chiu YL, Della Valle AG, Mazumdar M. In-hospital patient falls after total joint arthroplasty: incidence, demographics, and risk factors in the United States. J Arthroplasty2012; 27:823– 828.e1. 29. Ilfeld BM. Continuous peripheral nerve blocks: a review of the published evidence. Anesth Analg 2011; 113:904–925. 30. Ilfeld BM, Fredrickson MJ, Mariano ER. Ultrasound-guided perineural catheter insertion: three approaches but few illuminating data. Reg Anesth Pain Med 2010; 35:123–126. 31. Sandhu NS, Capan LM. Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth 2002; 89:254–259. 1662
32. Swenson JD, Davis JJ, DeCou JA. A novel approach for assessing catheter position after ultrasound-guided placement of continuous interscalene block. Anesth Analg 2008; 106:1015–1016. 33. Morin AM, Eberhart LH, Behnke HK, et al. Does femoral nerve catheter placement with stimulating catheters improve effective placement? A randomized, controlled, and observer-blinded trial. Anesth Analg 2005; 100:1503–1510. 34. Casati A, Fanelli G, Koscielniak-Nielsen Z, et al. Using stimulating catheters for continuous sciatic nerve block shortens onset time of surgical block and minimizes postoperative consumption of pain medication after halux valgus repair as compared with conventional nonstimulating catheters. Anesth Analg 2005; 101:1192–1197. 35. Aveline C, Le Roux A, Le Hetet H, Vautier P, Cognet F, Bonnet F. Postoperative efficacies of femoral nerve catheters sited using ultrasound combined with neurostimulation compared with neurostimulation alone for total knee arthroplasty. Eur J Anaesthesiol 2010; 27:978–984. 36. Kehlet H, Andersen LO. Local infiltration analgesia in joint replacement: the evidence and recommendations for clinical practice. Acta Anaesthesiol Scand 2011; 55:778–784. 37. Mariano ER, Cheng GS, Choy LP, et al. Electrical stimulation versus ultrasound guidance for popliteal-sciatic perineural catheter insertion: a randomized controlled trial. Reg Anesth Pain Med 2009; 34:480–485. 38. Mariano ER, Loland VJ, Sandhu NS, et al. Comparative efficacy of ultrasound-guided and stimulating popliteal-sciatic perineural catheters for postoperative analgesia. Can J Anaesth 2010; 57:919–926. 39. Oldman M, McCartney CJ, Leung A, et al. A survey of orthopedic surgeons’ attitudes and knowledge regarding regional anesthesia. Anesth Analg 2004; 98:1486–1490. 40. Dhir S, Ganapathy S. Use of ultrasound guidance and contrast enhancement: a study of continuous infraclavicular brachial plexus approach. Acta Anaesthesiol Scand 2008; 52:338–342. 41. Fredrickson MJ, Price DJ. Analgesic effectiveness of ropivacaine 0.2% vs 0.4% via an ultrasound-guided C5-6 root/superior trunk perineural ambulatory catheter. Br J Anaesth 2009; 103:434–439. 42. Swenson JD, Bay N, Loose E, et al. Outpatient management of continuous peripheral nerve catheters placed using ultrasound guidance: an experience in 620 patients. Anesth Analg 2006; 103:1436–1443.
J Ultrasound Med 2014; 33:1653–1662
ORIGINAL RESEARCH
A Randomized Comparison of Proximal and Distal Ultrasound-Guided Adductor Canal Catheter Insertion Sites for Knee Arthroplasty Edward R. Mariano, MD, MAS, T. Edward Kim, MD, Michael J. Wagner, MD, Natasha Funck, MD, T. Kyle Harrison, MD, Tessa Walters, MD, Nicholas Giori, MD, PhD, Steven Woolson, MD, Toni Ganaway, BA, Steven K. Howard, MD Objectives—Proximal and distal (mid-thigh) ultrasound-guided continuous adductor canal block techniques have been described but not yet compared, and infusion benefits or side effects may be determined by catheter location. We hypothesized that proximal placement will result in faster onset of saphenous nerve anesthesia, without additional motor block, compared to a distal technique.
Received November 13, 2013, from the Departments of Anesthesiology, Perioperative and Pain Medicine (E.R.M., T.E.K., M.J.W., N.F., T.K.H., T.W., T.G., S.K.H.) and Orthopedic Surgery (N.G., S.W.), VA Palo Alto Health Care System, Palo Alto, California USA; and Stanford University School of Medicine, Stanford, California USA. Revision requested December 3, 2013. Revised manuscript accepted for publication December 18, 2013. We gratefully acknowledge the invaluable assistance of the entire operating and recovery room staff at the VA Palo Alto Health Care System, especially our regional anesthesia and acute pain medicine fellows, Brett Miller, MD, Justin Workman, MD, Genie Kim, MD, Jody Leng, MD, and Michael Rasmussen, MD. Dr Mariano has received unrestricted educational program funding paid to his institution fro m I-Flow/KimberlyClark (Lake Forest, CA) and B. Braun (Bethlehem, PA). These companies had no input into any aspect of the study design and implementation; data collection, analysis, and interpretation; or manuscript preparation. Address correspondence to Edward R. Mariano, MD, MAS, Anesthesiology and Perioperative Care Service, VA Palo Alto Health Care System, 3801 Miranda Ave, 112A, Palo Alto, CA 94304 USA. E-mail: [email protected] Abbreviations
IV, intravenous doi:10.7863/ultra.33.9.1653
Methods—Preoperatively, patients receiving an ultrasound-guided nonstimulating adductor canal catheter for knee arthroplasty were randomly assigned to either proximal or distal insertion. A local anesthetic bolus was administered via the catheter after successful placement. The primary outcome was the time to achieve complete sensory anesthesia in the saphenous nerve distribution. Secondary outcomes included procedural time, procedure-related pain and complications, postoperative pain, opioid consumption, and motor weakness. Results—Proximal insertion (n = 23) took a median (10th–90th percentiles) of 12.0 (3.0–21.0) minutes versus 6.0 (3.0–21.0) minutes for distal insertion (n = 21; P = .106) to anesthetize the medial calf. Only 10 of 25 (40%) and 10 of 24 (42%) patients in the proximal and distal groups, respectively, developed anesthesia at both the medial calf and top of the patella (P = .978). Bolus-induced motor weakness occurred in 19 of 25 (76%) and 16 of 24 (67%) patients in the proximal and distal groups (P = .529). Ten of 24 patients (42%) in the distal group required intravenous morphine postoperatively, compared to 2 of 24 (8%) in the proximal group (P = .008), but there were no differences in other secondary outcomes. Conclusions—Continuous adductor canal blocks can be performed reliably at both proximal and distal locations. The proximal approach may offer minor analgesic and logistic advantages without an increase in motor block. Key Words—continuous adductor canal block; knee arthroplasty; musculoskeletal ultrasound; perineural catheter; ultrasound-guided regional anesthesia
F
or major knee surgery, including total knee arthroplasty, a continuous adductor canal block with perineural catheter insertion may provide effective postoperative analgesia.1–4 In addition, an adductor canal block may preserve quadriceps strength to a greater extent than a femoral nerve block.3,5,6 Retrospective cohort studies suggest that this strength advantage may result in improved early ambulatory ability after total knee arthroplasty.7,8
©2014 by the American Institute of Ultrasound in Medicine | J Ultrasound Med 2014; 33:1653–1662 | 0278-4297 | www.aium.org
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1654
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
There is some controversy regarding the optimal location for adductor canal catheter placement. The mid-thigh catheter insertion site has been previously described,1–5,9 but this location is invariably within the planned sterile surgical field. Alternatively, a more proximal approach has been described,10 also referred to as the “selective femoral nerve block.” This technique targets the adductor canal at its entrance just distal to the apex of the femoral triangle and has been shown to spare the motor branches to the quadriceps in a cadaver study.10 A proximal technique offers the potential advantages of faster block onset from more cephalad spread, as described for femoral nerve catheters,11 and a catheter location further displaced from the surgical field but still runs the theoretical risk of quadriceps weakness if the main femoral nerve becomes anesthetized.12 To date, these two approaches have not been compared head to head; therefore, any potential infusion benefits or side effects attributable to catheter location remain unknown. We designed this study to test the hypothesis that proximal placement will result in faster onset of saphenous nerve anesthesia, without additional motor block, compared to a distal (mid-thigh) technique.
Materials and Methods This study was approved by the Institutional Review Board of Stanford University and the Veterans Affairs Research and Development Committee of the VA Palo Alto Health Care System and prospectively registered at http://www.clinicaltrials.gov (NCT01459523). Adults (>18 years old) scheduled for unilateral knee arthroplasty with an adductor canal perineural catheter planned for postoperative analgesia were considered for inclusion. Patients unable to understand the study protocol or care for the infusion pump/catheter system or with any known contraindication to study medications or regional anesthesia, insulin-dependent diabetes mellitus, neuropathy of any etiology in the affected extremity, hepatic or renal failure, any additional surgical site outside the limb intended for catheter placement, chronic opioid use or active illicit substance abuse, pregnancy, or an inability to communicate with the investigators and hospital staff were excluded. Protocol After providing written informed consent, patients were randomly assigned to one of two treatment groups, proximal (selective femoral) or distal (mid-thigh), using sealed envelopes containing group assignments based on a computergenerated randomization sequence (http://www. randomizer.org). All procedures were performed by an
1654
attending regional anesthesiologist experienced in both placement techniques or by a regional anesthesiology and acute pain medicine fellow directly supervised by the attending anesthesiologist. Patients and the research assistant performing assessments were blinded to group assignment. Each patient’s ability to perform a straight leg raise in the supine position, defined as raising the heel off the bed at least 6 in (15 cm) with the leg extended and hip flexed,13 on the surgical and nonsurgical side was assessed at baseline. After peripheral intravenous (IV) catheter insertion and positioning, standard noninvasive monitors and oxygen via a face mask or nasal cannulas were applied. Patients received IV midazolam and fentanyl titrated to their comfort but maintaining verbal responsiveness. The planned procedural area was sterilely cleansed with chlorhexidine gluconate and isopropyl alcohol (ChloraPrep One-Step; CareFusion, Leawood, KS), and a clear fenestrated sterile drape was applied. The ultrasound machine (M-Turbo HFL38; SonoSite, Inc, Bothell, WA) with a 13–6-MHz linear array ultrasound transducer placed in a sterile sleeve was prepared for use. Proximal Technique Patients randomized to the proximal group underwent perineural catheter insertion using a slight modification of a method described previously.10 After the femoral nerve was identified in the short axis near the inguinal crease, the ultrasound transducer was moved caudally beyond the apex of the femoral triangle and distal to the bifurcation of the femoral artery, where the medial border of the sartorius muscle first covers the superficial femoral artery at the entry to the adductor canal (Figure 1). A local anesthetic (1% lidocaine) skin wheal was raised 1 cm lateral to the transducer, and the same local anesthetic solution was deposited along the planned trajectory of the catheter placement needle. An uninsulated, 8.9-cm, 17-gauge Tuohy-tip needle (Arrow FlexTip Plus; Teleflex Medical, Research Triangle Park, NC) was inserted through the skin wheal and directed in-plane beneath the transducer in a medial direction toward the target nerve until the needle tip passed through the sartorius muscle and entered the adductor canal lateral to the target nerve and superficial femoral artery. An initial injection of 5 mL (5% dextrose in water) was made via the placement needle, and then a 19-gauge flexible epidural-type catheter (Arrow FlexTip Plus) was inserted through the length of the needle and advanced 1 to 3 cm beyond the needle tip posterior to the nerve under direct ultrasound visualization with an assistant stabilizing the transducer (Figure 2). Once the catheter was placed, the needle was withdrawn over the catheter while inserting
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1655
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
additional catheter length into the sartorius muscle and overlying subcutaneous tissue layer, and the catheter tip position was assessed by injecting 0.5 mL of air via the catheter under ultrasound imaging.14 After negative aspiration for blood, 15 mL of an anesthetic solution (2% mepivacaine with epinephrine, 2.5 μg/mL) was injected incrementally via the catheter. Distal Technique Patients randomized to the distal technique underwent adductor canal perineural catheter insertion using a method
Figure 1. Unembalmed cadaver dissection illustrating the course of the saphenous nerve and the sites of perineural catheter insertion for this study. X indicates sartorius muscle (displaced medially to expose the saphenous nerve); asterisk, saphenous nerve; white arrow, approximate catheter insertion site for the proximal group; and black arrow, approximate catheter insertion site for the distal (mid-thigh) group.
described previously.4 After the saphenous nerve was identified in the short axis, deep to the sartorius muscle and lateral to the superficial femoral artery and approximately halfway between the anterior superior iliac spine and the patella, catheter insertion proceeded stepwise in a similar manner as in the proximal group. The perineural catheter was advanced 1 to 3 cm beyond the needle tip posterior to the nerve under direct ultrasound visualization with an assistant stabilizing the transducer (Figure 3). Catheter placement was confirmed and injectate delivered in the same manner as in the proximal group. Figure 2. Short-axis image of the saphenous nerve in the adductor canal during proximal placement of a perineural catheter. A indicates superficial femoral artery; N, saphenous nerve; S, sartorius muscle; asterisk, distal end of the needle; and arrowheads, distal end of the catheter.
Figure 3. Short-axis image of the saphenous nerve in the adductor canal during distal (mid-thigh) placement of a perineural catheter. Abbreviations and symbols are as in Figure 2.
J Ultrasound Med 2014; 33:1653–1662
1655
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1656
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
All catheters were tunneled subcutaneously per protocol in a cephalad and lateral direction toward the anterior
superior iliac spine using the placement needle and its stylet, as described previously (Figure 4).15 The catheter
Figure 4. Subcutaneous tunneling technique. A, The stylet is inserted into the same entry hole from which the catheter emerges. B, The stylet is advanced subcutaneously in a cephalad and lateral direction toward the anterior superior iliac spine. C, The placement needle is inserted over the tip of the stylet. D, The placement needle is advanced along the same subcutaneous track using the stylet as a guide. E, The proximal end of the catheter is inserted into the tip of the placement needle after the stylet is removed. F, The placement needle is withdrawn after the catheter emerges from the hub, and the catheter is pulled until the remaining catheter loop is buried within the subcutaneous layer.
1656
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1657
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
was secured with clear occlusive dressings and an anchoring device (StatLock; Bard Medical, Covington, GA), and the catheter insertion site was covered with a blanket to obscure the catheter location before assessment by the research assistant to maintain blinding. If a catheter was not placed successfully per protocol (within 30 minutes), the patient was removed from the study but was still eligible to receive a nerve block or perineural catheter placed by the patient’s regional anesthesiologist using any technique at his or her discretion. Primary Outcome The onset time (minutes) for complete sensory anesthesia was the primary outcome and was measured after completion of the mepivacaine bolus. Sensory assessments were performed using pinprick sensation (0, no change from baseline; 1, diminished pinprick sensation; 2, no pinprick sensation)16,17 in the medial calf proximal to the medial malleolus and the top of the patella by a blinded research assistant every 3 minutes for up to 30 minutes, with a score of 2 in the medial calf distribution considered complete sensory anesthesia of the saphenous nerve. Patients without anesthetic onset at 30 minutes were considered to have had unsuccessful catheter placements and were withdrawn from further study; catheters were retained and reassessed postoperatively for possible replacement. Secondary Outcomes During the procedure, the following measurements were recorded: catheter placement time (minutes) beginning when the ultrasound transducer first touched the patient’s skin and ending when the placement needle was removed after catheter insertion, number of needle passes (each withdrawal of the placement needle >1 cm plus redirection counting as an additional pass), amount of IV fentanyl (micrograms) administered, and number of vascular punctures. Immediately after catheter insertion, patients were asked to rate their procedure-related discomfort on a numeric rating scale of 0 to 10 (0, no discomfort; 10, worst discomfort imaginable). Motor assessments of the quadriceps were performed by voluntary leg extension against resistance with the patient in the supine position and the hip passively flexed (0, no change from baseline; 1, diminished active contraction; 2, no active contraction) by a blinded research assistant every 3 minutes for up to 30 minutes, with a score of 2 considered a complete motor block. All patients received general anesthesia, although the intraoperative anesthetic technique was not standardized. At the conclusion of surgery, all patients received periarticular injections of 0.2% ropivacaine (150 mL) and
J Ultrasound Med 2014; 33:1653–1662
epinephrine (2.5 μg/mL) with ketorolac (30 mg) divided equally within the posterior capsule, retinacular layer, and subcutaneous tissue per institutional protocol.18,19 The amount of IV opioid (eg, micrograms of fentanyl or milligrams of morphine) administered intraoperatively and in the postanesthesia care unit was recorded. Each perineural catheter was attached to a portable infusion device (ON-Q C-bloc with ONDEMAND; I-Flow Corporation, Lake Forest, CA) set to deliver an infusion of 0.2% ropivacaine (basal rate of 6 mL/h; patient-controlled bolus of 5 mL; and lockout interval of 30 minutes). Patients were prescribed scheduled oxycodone, acetaminophen, and diclofenac plus additional oral oxycodone and IV morphine for breakthrough postoperative pain inadequately treated with the perineural ropivacaine infusion and bolus. None of the patients were prescribed IV opioid patient-controlled analgesia, per our institutional clinical analgesic protocol.7 On postoperative day 1, patients were evaluated in person by a blinded research assistant to collect information regarding average and worst postsurgical pain (numeric rating scale of 0–10), opioids consumed (milligrams of oxycodone and/or IV morphine), number of sleep disturbances, satisfaction with pain control using a Likert scale (0, not at all satisfied; 10, extremely satisfied), leakage of fluid from the catheter site, ability to perform the straight leg raise, and a subjective rating of numbness (0, normal sensation; 10, completely insensate). After completion of study-related procedures, clinical regional anesthesiology and perioperative analgesia staff continued to follow all patients daily for the duration of their perineural infusions. Sample Size Estimate The onset time for complete sensory anesthesia in the distribution of the target nerve was the primary outcome. Using published onset times for ultrasound-guided femoral perineural catheters by a short-axis, in-plane technique with a through-the-catheter bolus of mepivacaine,11 2-sided type I error protection of .05, and power of 80%, 21 patients in each treatment arm were required to detect a difference between treatment group means of 5 minutes, which was considered relevant to our clinical practice and would clearly demonstrate an advantage of one catheter insertion location over the other. We enrolled 25 patients per group to account for unanticipated patient dropout or protocol violations. Statistical Analysis Statistical analysis was performed with NCSS-PASS statistical software (NCSS, Kaysville, UT) by an investigator blinded to study group identity. Normality of distribution
1657
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1658
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
was determined for all scale variables. For normally distributed data, single comparisons were performed using the Student t test; for continuous data in distributions other than normal, the Mann-Whitney U test was used. The z test or Barnard exact test (n < 5 in any field) were used for comparisons of categorical data. Intent to treat was applied for all analyses, and 2-sided P < .05 was considered statistically significant for the primary outcome. Statistically significant findings for secondary outcomes should be interpreted as suggestive, requiring confirmation in a prospective trial before being considered definitive.20
Results Seventy-seven patients were assessed for eligibility; 17 patients did not meet the criteria for enrollment; 2 declined to participate; 1 was interested but not enrolled due to cancellation of surgery; and 7 were not enrolled because of time constraints. Fifty patients were enrolled and randomly assigned to one of the two study groups. Demographic and morphometric characteristics were similar between groups (Table 1). At baseline, 92% (23 of 25) and 83% (20 of 24) patients in the proximal and distal groups, respectively, were able to perform a straight leg raise (P = .528). Median (10th–90th percentiles) for elevation of the heel on the surgical side during the straight leg raise before surgery was 46 (28–48) cm for the proximal group (n = 23) versus 48 (31–48) cm for the distal group (n = 20; P = .556). All patients in the proximal group (n = 25) underwent successful catheter insertion per protocol. In the distal group (n = 25), 1 patient (body mass index, 47 kg/m2) failed catheter placement per protocol due to inadvertent dislodgement after tunneling and was withdrawn from the study, but he did receive a perineural catheter for postoperative analgesia at the regional anesthesiologist’s discretion. Table 1. Morphometric Data and Procedural Information Parameter Age, y Female/male, n ASA physical status Height, cm Weight, kg Body mass index, kg/m2 Attending/fellow placement, n Knee arthroplasty procedure, n Primary unicompartmental Primary total
Proximal (n = 25)
Distal (n = 24)
66 (59–75) 0/25 3 (2–3) 177 (170–185) 102 (84–136) 33 (28–41) 2/23
65 (57–71) 0/24 3 (2–3) 178 (168–185) 97 (76–128) 30 (25–39) 1/23
1 24
1 23
Values are reported as median (10th–90th percentiles) where applicable. ASA indicates American Society of Anesthesiologists.
1658
One patient in the proximal group did not provide postoperative follow-up data because surgery was canceled after anesthetic induction due to traumatic urinary catheter insertion. Primary Outcome Ninety-two percent (23 of 25) and 88% (21 of 24) of patients in the proximal and distal groups, respectively, achieved complete sensory anesthesia within 30 minutes (P = .707); the 5 patients who did not were found to have saphenous nerve anesthesia postoperatively, and their catheters were retained. Proximal insertion (n = 23) took a median (10th–90th percentiles) of 12.0 (3.0–21.0) minutes versus 6.0 (3.0–21.0) minutes for distal insertion (n = 21; P = .106) to anesthetize the medial calf. Only 10 of 25 (40%) and 10 of 24 (42%) patients in the proximal and distal groups developed anesthesia at both the medial calf and top of the patella (P = .978). Secondary Outcomes Proximal catheter placement procedures took 6.0 (4.0–8.6) minutes to perform compared to 6.0 (4.0–8.7) for distal (P = .808). Any bolus-induced motor weakness, partial or complete, within 30 minutes occurred in 19 of 25 (76%) and 16 of 24 (67%) patients in the proximal and distal groups, respectively (P = .529). There were no vascular punctures in either group and no differences in other procedure-related secondary outcomes (Table 2). Combined intraoperative and postanesthesia care unit opioid consumption was similar: 275 (200–380) versus 250 (150–400) μg of IV fentanyl (proximal and distal, respectively; P = .372) and 5.0 (0.0–11.2) versus 2.5 (0.0–10.0) mg of IV morphine (proximal and distal; P = .302). No catheters were inadvertently dislodged overnight in either group. In the first 24 hours after surgery, more patients in the distal group, 10 of 24 (42%), required IV morphine compared to 2 of 24 (8%) in the proximal group (P = .008). Table 2. Secondary Outcomes Related to Perineural Catheter Placement Parameter Needle passes, n Fentanyl, μg Procedural pain, NRS 0–10 No motor block, n Partial motor block, n Complete motor block, n
Proximal (n = 25)
Distal (n = 24)
P
1 (1–1) 50 (35–100) 1 (0–4) 6 9 10
1 (1–1) 50 (50–100) 2 (0–3) 8 9 7
.977 .274 .838 .529 .996 .529
Values are reported as median (10th–90th percentiles) where applicable. NRS indicates numeric rating scale.
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1659
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
The distal group required more IV morphine for breakthrough pain: 0.0 (0.0–7.4) versus 0.0 (0.0–0.0) mg in the proximal group (P = .009), but total opioid consumption (milligram of morphine equivalents) was similar: 23.3 (11.0–41.9) versus 23.3 (14.9–48.3) mg for the proximal and distal groups (P = .884). On postoperative day 1, 58% (14 of 24) and 54% (13 of 24) of patients in the proximal and distal groups were able to perform a straight leg raise (P = .873). Elevation of the heel on the surgical side during the straight leg raise was 46 (20–48) cm for the proximal group (n = 14) versus 38 (16–48) cm for the distal group (n = 13; P = .306). There were no differences in other postoperative day 1 secondary outcomes (Table 3). One patient, who was assigned to the distal group according to the computer-generated randomization sequence, inadvertently received a catheter placement in the proximal position; this error was not detected until after surgery and completion of data collection. The patient’s data were included in the distal group for analyses according to intent to treat. Inclusion of the patient in the proximal group based on actual treatment did not affect the results of the primary outcome (12.0 [3.0–21.0] versus 6.0 [3.0–21.9] minutes for proximal and distal, respectively; P = .108) or other secondary outcome analyses. There were no other protocol violations or adverse events related to the study procedures.
Discussion Continuous adductor canal blocks can be performed reliably at both proximal and distal locations, although a greater proportion of patients who receive proximal catheters are IV morphine-free for the first 24 hours after surgery. There is no difference in onset time for sensory anesthesia in the saphenous distribution below the knee, and less than half of patients in both groups have sensory anesthesia to the top of the patella. Bolus-induced motor weakness of
Table 3. Secondary Outcomes on Postoperative Day 1 Parameter Fluid leakage at site, n Numbness, Likert 0–10 Average pain, NRS 0–10 Worst pain, NRS 0–10 Awakenings from pain, n Satisfaction, Likert 0–10
Proximal (n = 24)
Distal (n = 24)
P
2 0.0 (0.0–2.7) 3.5 (0.1–6.0) 7.0 (2.6–10.0) 0.0 (0.0–2.0) 10.0 (8.3–10.0)
1 0.0 (0.0–4.7) 5.0 (1.0–8.0) 7.5 (0.3–10.0) 0.5 (0.0–10) 10.0 (8.0–10.0)
.596 .298 .121 .966 .079 .337
Values are reported as median (10th–90th percentiles) where applicable. NRS indicates numeric rating scale.
J Ultrasound Med 2014; 33:1653–1662
the quadriceps muscle can be detected in most patients in both groups, and nearly half of patients are unable to perform the straight leg raise on the day after surgery, with no difference between groups. Quadriceps Weakness and Peripheral Nerve Blocks Nerve blocks of the lumbar plexus,21 particularly femoral nerve blocks,12 have been shown to decrease quadriceps strength through local anesthetic-induced conduction blockade of motor nerves. In recent years, a great deal of negative attention has been cast on the potential role of peripheral nerve blocks in increasing the fall risk for patients undergoing total joint arthroplasty.22,23 Although debate continues, and new data suggest no association,24 many hospitals and anesthesiology practices that may not have comprehensive multicomponent fall prevention programs in place25 may be searching for an alternative to replace femoral nerve blocks within their pain management protocols for total knee arthroplasty. Current local anesthetic medications are nonselective and cannot pharmacologically choose to spare motor nerves versus sensory nerves. Therefore, the potential to select anatomic sites, such as the adductor canal,4,10 that may be less likely to expose motor nerves to a local anesthetic solution seems particularly attractive. Human volunteer studies have shown that adductor canal blocks spare quadriceps motor strength to a greater degree than femoral nerve blocks,5,6 and this quadriceps strength advantage may also occur in the clinical setting after total knee arthroplasty.3 However, ambulation advantages favoring adductor canal blocks reported by retrospective cohort studies7,8 have yet to be reproduced by randomized clinical trials. This study demonstrates that bolus-induced motor weakness of the quadriceps does occur after injecting a local anesthetic via an adductor canal catheter placed in either the proximal or distal (mid-thigh) location and may be attributable to cephalad spread of the local anesthetic to the main femoral nerve in a patient population with preexisting quadriceps weakness and diminished preoperative function, although anesthetizing the nerve to the vastus medialis may also be partially responsible. In a cadaver study and case series reported by Ishiguro et al,10 proximal pressure during dye and local anesthetic injection, respectively, was reported to decrease the likelihood of cephalad solution spread. We elected not to perform this maneuver, since it is not routinely part of our ultrasound-guided perineural catheter insertion technique for patients undergoing total knee arthroplasty11,26; this maneuver is not included in the distal approach; and there is no anatomic barrier between the femoral triangle and adductor canal to
1659
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1660
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
prevent late spread of an injectate solution.10 Our incidence of bolus-induced quadriceps muscle weakness does caution against the use of high-dose longer-acting local anesthetic solutions (eg, ropivacaine and bupivacaine) when patients are expected to bear weight on the operated extremity shortly after surgery. Previous studies using the mid-thigh approach have reported using a larger-volume initial bolus (30 mL) with 15-mL intermittent boluses every 6 hours postoperatively.4,9 Although the optimal local anesthetic regimen for adductor canal catheters is not known, a basal-bolus7 or basal rate-only3 regimen may have theoretical advantages in avoiding cephalad spread of the local anesthetic over a bolus-only regimen given the results of this study.1 Furthermore, our data showing that nearly half of patients cannot perform the straight leg raise on postoperative day 1 are consistent with a study by Jaeger et al,3 in which the median strength of patients receiving adductor canal catheters was 52% of baseline. Although patients with adductor canal blocks may have greater preservation of quadriceps strength compared to patients with femoral nerve blocks,3 quadriceps dysfunction after total knee arthroplasty can continue to be expected despite the use of an adductor canal block due to a variety of factors, such as preexisting weakness, surgical trauma, and age-related limitations in recovery of function even when a block is not performed at all.27 The risk of an inpatient fall in patients undergoing joint arthroplasty is multifactorial, with known contributors including advanced age, revision surgery, male sex, and increased comorbidity burden,28 and the occurrence of an inpatient fall may still occur in the presence of an adductor canal catheter. Regardless of the regional analgesic technique, all patients who undergo total knee arthroplasty should be considered at risk for an inpatient fall, and continued emphasis on multidisciplinary fall prevention is warranted. Catheter Tip Location and Onset Time To our knowledge, this study was the first to compare the efficacy of one site for adductor canal perineural catheter insertion to another. Although previous studies suggest that adductor canal catheters may offer analgesic benefits to patients after total knee arthroplasty,1–4 the optimal site for placement has remained unknown; furthermore, the distal (mid-thigh) approach may dissuade preoperative placement in clinical practice due to the location within the planned sterile surgical field. We sought to compare this approach to a more proximal technique10 to identify any potential advantages and/or disadvantages of each method. Since current regional anesthesia catheters are dif-
1660
ficult to visualize with ultrasound,29,30 requiring alternative strategies to infer the tip location,31,32 we chose the onset time for sensory anesthesia in the saphenous distribution as the surrogate outcome for catheter placement accuracy, as performed in previous studies.33–35 We chose a 5-minute difference as clinically relevant in the setting of a busy orthopedic surgery practice in which catheter placement success must be evaluated efficiently, and timely anesthetic onset before the start of surgery provides the patient and the anesthesiologist with confidence that the perineural catheter will be effective for analgesia in the postoperative period. This study did not show a statistically significant difference in onset time despite a 6-minute difference in the median onset time between groups; this result still may be attributable to a type II error, since the sample size was calculated on the basis of 80% power (β = .2), and we can speculate that a larger sample size may have shown a different result. However, we believe that a clearly superior catheter location should have shown a consistent advantage in terms of local anesthetic bolus distribution and sensory onset time within our calculated sample size. Interestingly, less than half of the patients in both groups developed sensory anesthesia to the top of the patella after the initial bolus, which indicates that the actual total knee arthroplasty incision may be incompletely anesthetized. Although local infiltration analgesia may complement adductor canal blocks in a multimodal analgesic protocol, it does not routinely last beyond 12 hours.36 A greater number of patients in the distal adductor canal catheter group did require IV morphine in the first 24 hours after surgery compared to the proximal group, suggesting perhaps that a more proximally placed catheter provides an analgesic advantage. However, there was no difference in total opioid consumption (milligram of morphine equivalents) between groups overall, and these secondary outcome findings require confirmation in a larger follow-up clinical trial. Catheter Placement Time There was no difference in catheter insertion times between the two techniques. For the purpose of measuring and comparing procedural times in this study, since both techniques used the same equipment, including ultrasound, we did not include the time required to prepare equipment, position and sedate the patient, sterilize and drape the procedural field and ultrasound equipment, perform the preprocedure timeout, and subcutaneously tunnel and secure the catheter after placement, similar to previous studies.26,37,38 We acknowledge that all of these steps can be expected to add to the total procedural time.
J Ultrasound Med 2014; 33:1653–1662
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1661
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
However, although we elected to subcutaneously tunnel all study catheters for the purpose of standardization per protocol, we believe that the location of the proximal approach (Figure 1) may not require further tunneling, since the catheter insertion site is already displaced cephalad from the planned surgical field. We speculate that eliminating the need to tunnel proximally inserted adductor canal catheters will decrease the total time required to perform this approach. In addition, the proximity in location and similarity in technique to the short-axis, in-plane femoral perineural catheter technique11,26 may facilitate adoption of adductor canal catheters for anesthesiology practices that wish to do so. Procedural efficiency in regional anesthesia on the day of surgery remains an important influencing factor for surgeons to recommend these effective analgesic techniques to their patients.39
References 1.
2.
3.
4.
5.
Study Limitations This study was not designed to compare adductor canal to femoral perineural catheters. For those anesthesiology practices that are interested in adopting adductor canal perineural catheters into their multimodal analgesic protocol for patients undergoing total knee arthroplasty, this study attempts to provide useful information regarding the optimal site for placement. The main limitation in this study design was that it was not truly double or triple blinded. The patients and the outcome assessor were blinded, and statistical analyses were performed before revealing group identity, but the regional anesthesiologists performing the study procedures were not blinded. In addition, the sample size for this study was small, increasing the likelihood of a type II error, and the intraoperative anesthetic protocol was not standardized. Generalizability of the study results is limited to practices using similar techniques and equipment as those used in this study; however, the equipment used was identical to that used in previously published studies.11,26 The use of other acceptable ultrasound-guided perineural catheter insertion techniques and equipment40–42 may produce different results.
6.
7.
8.
9.
10.
11.
12.
Conclusions In summary, ultrasound-guided adductor canal perineural catheter placement may be reliably performed in both proximal and distal locations. Bolus-induced quadriceps weakness can occur with both techniques, and postoperative quadriceps weakness remains common despite the use of adductor canal catheters. A more proximal approach may offer minor analgesic and logistic advantages without an increase in motor block, but these results require further confirmation.
J Ultrasound Med 2014; 33:1653–1662
13.
14.
15.
Andersen HL, Gyrn J, Moller L, Christensen B, Zaric D. Continuous saphenous nerve block as supplement to single-dose local infiltration analgesia for postoperative pain management after total knee arthroplasty. Reg Anesth Pain Med 2013; 38:106–111. Jaeger P, Grevstad U, Henningsen MH, Gottschau B, Mathiesen O, Dahl JB. Effect of adductor-canal-blockade on established, severe post-operative pain after total knee arthroplasty: a randomised study. Acta Anaesthesiol Scand 2012; 56:1013–1019. Jaeger P, Zaric D, Fomsgaard JS, et al. Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty: a randomized, double-blind study. Reg Anesth Pain Med 2013; 38:526–532. Lund J, Jenstrup MT, Jaeger P, Sorensen AM, Dahl JB. Continuous adductor-canal-blockade for adjuvant post-operative analgesia after major knee surgery: preliminary results. Acta Anaesthesiol Scand 2011; 55:14–19. Jaeger P, Nielsen ZJ, Henningsen MH, Hilsted KL, Mathiesen O, Dahl JB. Adductor canal block versus femoral nerve block and quadriceps strength: a randomized, double-blind, placebo-controlled, crossover study in healthy volunteers. Anesthesiology 2013; 118:409–415. Kwofie MK, Shastri UD, Gadsden JC, et al. The effects of ultrasoundguided adductor canal block versus femoral nerve block on quadriceps strength and fall risk: a blinded, randomized trial of volunteers. Reg Anesth Pain Med 2013; 38:321–325. Mudumbai SC, Kim TE, Howard SK, et al. Continuous adductor canal blocks are superior to continuous femoral nerve blocks in promoting early ambulation after TKA. Clin Orthop Relat Res 2014; 472:1377–1383. Perlas A, Kirkham KR, Billing R, et al. The impact of analgesic modality on early ambulation following total knee arthroplasty. Reg Anesth Pain Med 2013; 38:334–339. Jenstrup MT, Jaeger P, Lund J, et al. Effects of adductor-canal-blockade on pain and ambulation after total knee arthroplasty: a randomized study. Acta Anaesthesiol Scand 2012; 56:357–364. Ishiguro S, Yokochi A, Yoshioka K, et al. Technical communication: anatomy and clinical implications of ultrasound-guided selective femoral nerve block. Anesth Analg 2012; 115:1467–1470. Mariano ER, Kim TE, Funck N, et al. A randomized comparison of longand short-axis imaging for in-plane ultrasound-guided femoral perineural catheter insertion. J Ultrasound Med 2013; 32:149–156. Charous MT, Madison SJ, Suresh PJ, et al. Continuous femoral nerve blocks: varying local anesthetic delivery method (bolus versus basal) to minimize quadriceps motor block while maintaining sensory block. Anesthesiology 2011; 115:774–781. Walter F, Haynes MB, Markel DC. A randomized prospective study evaluating the effect of patellar eversion on the early functional outcomes in primary total knee arthroplasty. J Arthroplasty 2007; 22:509–514. Kan JM, Harrison TK, Kim TE, Howard SK, Kou A, Mariano ER. An in vitro study to evaluate the utility of the “air test” to infer perineural catheter tip location. J Ultrasound Med 2013; 32:529–533. Boezaart AP. Continuous interscalene block for ambulatory shoulder surgery. Best Pract Res Clin Anaesthesiol 2002; 16:295–310. 1661
3309jum1531-1668online_Layout 1 8/21/14 8:33 AM Page 1662
Mariano et al—Proximal Versus Distal Adductor Canal Catheters
16. Buys MJ, Arndt CD, Vagh F, Hoard A, Gerstein N. Ultrasound-guided sciatic nerve block in the popliteal fossa using a lateral approach: onset time comparing separate tibial and common peroneal nerve injections versus injecting proximal to the bifurcation. Anesth Analg 2010; 110:635–637. 17. Cuvillon P, Nouvellon E, Ripart J, et al. A comparison of the pharmacodynamics and pharmacokinetics of bupivacaine, ropivacaine (with epinephrine) and their equal volume mixtures with lidocaine used for femoral and sciatic nerve blocks: a double-blind randomized study. Anesth Analg 2009; 108:641–649. 18. Essving P, Axelsson K, Aberg E, Spannar H, Gupta A, Lundin A. Local infiltration analgesia versus intrathecal morphine for postoperative pain management after total knee arthroplasty: a randomized controlled trial. Anesth Analg 2011; 113:926–933. 19. Tripuraneni KR, Woolson ST, Giori NJ. Local infiltration analgesia in TKA patients reduces length of stay and postoperative pain scores. Orthopedics 2011; 34:173. 20. Mariano ER, Ilfeld BM, Neal JM. “Going fishing”: the practice of reporting secondary outcomes as separate studies. Reg Anesth Pain Med 2007; 32:183–185. 21. Ilfeld BM, Moeller LK, Mariano ER, et al. Continuous peripheral nerve blocks: is local anesthetic dose the only factor, or do concentration and volume influence infusion effects as well? Anesthesiology 2010; 112:347–354. 22. Feibel RJ, Dervin GF, Kim PR, Beaule PE. Major complications associated with femoral nerve catheters for knee arthroplasty: a word of caution. J Arthroplasty 2009; 24:132–137. 23. Ilfeld BM, Duke KB, Donohue MC. The association between lower extremity continuous peripheral nerve blocks and patient falls after knee and hip arthroplasty. Anesth Analg 2010; 111:1552–1524. 24. Memtsoudis SG, Danninger T, Rasul R, et al. Inpatient falls after total knee arthroplasty: the role of anesthesia type and peripheral nerve blocks. Anesthesiology 2014; 120:551–563. 25. Miake-Lye IM, Hempel S, Ganz DA, Shekelle PG. Inpatient fall prevention programs as a patient safety strategy: a systematic review. Ann Intern Med 2013; 158:390–396. 26. Mariano ER, Loland VJ, Sandhu NS, et al. Ultrasound guidance versus electrical stimulation for femoral perineural catheter insertion. J Ultrasound Med 2009; 28:1453–1460. 27. Stevens-Lapsley JE, Balter JE, Kohrt WM, Eckhoff DG. Quadriceps and hamstrings muscle dysfunction after total knee arthroplasty. Clin Orthop Relat Res 2010; 468:2460–2468. 28. Memtsoudis SG, Dy CJ, Ma Y, Chiu YL, Della Valle AG, Mazumdar M. In-hospital patient falls after total joint arthroplasty: incidence, demographics, and risk factors in the United States. J Arthroplasty2012; 27:823– 828.e1. 29. Ilfeld BM. Continuous peripheral nerve blocks: a review of the published evidence. Anesth Analg 2011; 113:904–925. 30. Ilfeld BM, Fredrickson MJ, Mariano ER. Ultrasound-guided perineural catheter insertion: three approaches but few illuminating data. Reg Anesth Pain Med 2010; 35:123–126. 31. Sandhu NS, Capan LM. Ultrasound-guided infraclavicular brachial plexus block. Br J Anaesth 2002; 89:254–259. 1662
32. Swenson JD, Davis JJ, DeCou JA. A novel approach for assessing catheter position after ultrasound-guided placement of continuous interscalene block. Anesth Analg 2008; 106:1015–1016. 33. Morin AM, Eberhart LH, Behnke HK, et al. Does femoral nerve catheter placement with stimulating catheters improve effective placement? A randomized, controlled, and observer-blinded trial. Anesth Analg 2005; 100:1503–1510. 34. Casati A, Fanelli G, Koscielniak-Nielsen Z, et al. Using stimulating catheters for continuous sciatic nerve block shortens onset time of surgical block and minimizes postoperative consumption of pain medication after halux valgus repair as compared with conventional nonstimulating catheters. Anesth Analg 2005; 101:1192–1197. 35. Aveline C, Le Roux A, Le Hetet H, Vautier P, Cognet F, Bonnet F. Postoperative efficacies of femoral nerve catheters sited using ultrasound combined with neurostimulation compared with neurostimulation alone for total knee arthroplasty. Eur J Anaesthesiol 2010; 27:978–984. 36. Kehlet H, Andersen LO. Local infiltration analgesia in joint replacement: the evidence and recommendations for clinical practice. Acta Anaesthesiol Scand 2011; 55:778–784. 37. Mariano ER, Cheng GS, Choy LP, et al. Electrical stimulation versus ultrasound guidance for popliteal-sciatic perineural catheter insertion: a randomized controlled trial. Reg Anesth Pain Med 2009; 34:480–485. 38. Mariano ER, Loland VJ, Sandhu NS, et al. Comparative efficacy of ultrasound-guided and stimulating popliteal-sciatic perineural catheters for postoperative analgesia. Can J Anaesth 2010; 57:919–926. 39. Oldman M, McCartney CJ, Leung A, et al. A survey of orthopedic surgeons’ attitudes and knowledge regarding regional anesthesia. Anesth Analg 2004; 98:1486–1490. 40. Dhir S, Ganapathy S. Use of ultrasound guidance and contrast enhancement: a study of continuous infraclavicular brachial plexus approach. Acta Anaesthesiol Scand 2008; 52:338–342. 41. Fredrickson MJ, Price DJ. Analgesic effectiveness of ropivacaine 0.2% vs 0.4% via an ultrasound-guided C5-6 root/superior trunk perineural ambulatory catheter. Br J Anaesth 2009; 103:434–439. 42. Swenson JD, Bay N, Loose E, et al. Outpatient management of continuous peripheral nerve catheters placed using ultrasound guidance: an experience in 620 patients. Anesth Analg 2006; 103:1436–1443.
J Ultrasound Med 2014; 33:1653–1662
