Acta Anaesthesiol Scand 2012; 56: 357–364 © 2012 The Authors Printed in Singapore. All rights reserved Acta Anaesthesiologica Scandinavica © 2012 The Acta Anaesthesiologica Scandinavica Foundation ACTA ANAESTHESIOLOGICA SCANDINAVICA doi: 10.1111/j.1399-6576.2011.02621.x

Effects of Adductor-Canal-Blockade on pain and ambulation after total knee arthroplasty: a randomized study

M. T. Jenstrup1, P. Jæger2, J. Lund1, J. S. Fomsgaard3, S. Bache3, O. Mathiesen2, T. K. Larsen3 and J. B. Dahl2 1Department of Anaesthesia, Hamlet Hospital, Frederiksberg, Denmark, 2Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Denmark and 3Department of Anaesthesia, Copenhagen University Hospital, Glostrup, Denmark

Background: Total knee arthroplasty (TKA) is associated with compared with the placebo group (40 Ϯ 21 vs. 56 Ϯ 26 mg, intense post-operative pain. Besides providing optimal analge- P = 0.006). Pain was significantly reduced in the ropivacaine sia, reduction in side effects and enhanced mobilization are group during 45 degrees flexion of the knee (P = 0.01), but not at important in this elderly population. The adductor-canal- rest (P = 0.06). Patients in the ropivacaine group performed blockade is theoretically an almost pure sensory blockade. We the ambulation test, the Timed-Up-and-Go (TUG) test, at 24 h hypothesized that the adductor-canal-blockade may reduce mor- significantly faster than patients in the placebo group (36 Ϯ 17 phine consumption (primary endpoint), improve pain relief, vs. 50 Ϯ 29 s, P = 0.03). enhance early ambulation ability, and reduce side effects (sec- Conclusion: The adductor-canal-blockade significantly ondary endpoints) after TKA compared with placebo. reduced morphine consumption and pain during 45 degrees Methods: Patients aged 50–85 years scheduled for TKA were flexion of the knee compared with placebo. In addition, the included in this parallel double-blind, placebo-controlled rand- adductor-canal-blockade significantly enhanced ambulation omized trial. The patients were allocated to receive a continuous ability assessed by the TUG test. adductor-canal-blockade with intermittent boluses via a catheter with either ropivacaine 0.75% (n = 34) or placebo (n = 37) (http://www.clinicaltrials.gov Identifier: NCT01104883). Accepted for publication 17 November 2011 Results: Seventy-five patients were randomized in a 1 : 1 ratio © 2012 The Authors and 71 patients were analyzed. Morphine consumption from 0 Acta Anaesthesiologica Scandinavica to 24 h was significantly reduced in the ropivacaine group © 2012 The Acta Anaesthesiologica Scandinavica Foundation

otal knee arthroplasty (TKA) is associated with blocks involving the femoral nerve may be associ- Tintense, early post-operative pain. This surgical ated with the risk of falling.7–13 Consequently, population consists primarily of elderly patients, regional anesthesia techniques with preserved often with significant co-morbidity. The post- muscle function are warranted. operative analgesic regimen should aim to reduce A number of different nerves and nerve branches morbidity and enhance functional recovery as well traverse the adductor canal (Hunter’s canal), includ- as provide efficient analgesia with minimal side ing the saphenous nerve, the nerve to the vastus effects.1 medialis, the posterior branch of the obturator Femoral and lumbar nerve blocks are effective for nerve, and in some cases, the medial cutaneous post-operative pain relief after TKA.2–5 However, nerve and the anterior branch of the obturator femoral nerve block (FNB) reduces the strength of nerve.14 Except for the nerve to the vastus medialis, the quadriceps muscle by more than 80%.6 This these branches have a sole sensory function, and adverse effect is particularly undesirable because most of them play a major role in the sensory inner- early mobilization after surgery is important in vation of the knee region. We have recently hypoth- order to enhance functional recovery and to reduce esized that administration of high-volume local immobility-related complications. In addition, anesthetic into the adductor canal [(‘adductor-canal- recent reports have shown that peripheral nerve blockade’ (ACB)] could be a useful option for post- 357 M. T. Jenstrup et al. operative analgesia after TKA.14 This hypothesis discretion of the anesthetist, and a femoral tourni- has not, however, been investigated in controlled quet was used at the discretion of the surgeon. clinical trials. The ACB was performed immediately post- The objective of this prospective, randomized, operatively. At the midthigh level, approximately double-blind, placebo-controlled study was there- halfway between the superior anterior iliac spine fore to investigate the efficacy of ACB on opioid and the patella, a high-frequency linear ultrasound consumption, pain relief and ambulation ability (US) transducer (GE Logiq e, GE, Waukesha, WI, after TKA. We hypothesized that ACB would reduce USA) was placed in a transverse cross-sectional morphine consumption (primary endpoint), and view. Underneath the sartorius muscle the femoral improve pain relief, enhance ambulation ability and artery was identified, with the vein just inferior reduce side effects (secondary endpoints) after TKA and the saphenous nerve just lateral to the artery. compared with placebo. From the lateral side of the transducer a 10-cm, 18-gauge Tuohy needle (Braun Medical, Melsungen, Materials and methods Germany) was inserted in plane, through the sarto- rius muscle. With the tip of the Tuohy needle placed After approval was obtained from the local Regional just lateral to the artery and the saphenous nerve, Ethics Committee (H-1-2009-143), the Danish Medi- 20 ml of study medication was injected to expand cines Agency (2009-017794-37), and the Danish Data the adductor canal. A 21-gauge catheter was then Protection Agency, this prospective, randomized, inserted 5–8 cm through the canula. To obtain the double-blind, placebo-controlled, parallel group correct position of the catheter tip, the catheter was study was conducted at Hamlet Hospital, Frederiks- slowly retracted during injection of a further 10 ml berg and at Glostrup University Hospital, the of study medication under US guidance, until an Capital Region of Denmark. Written informed expansion between the fascia and the vessels could consent was obtained from all subjects. The study be visualized. All blocks were performed by one of was conducted in accordance with the Helsinki Dec- three anesthesiologists (M. T. J., J. L., J. S. F.), all with larations and the guidelines for Good Clinical Prac- considerable experience in US-guided nerve blocks. tice (GCP), and was monitored by the Copenhagen Patients were randomly assigned to receive either University Hospital GCP unit. Data are presented ACB with ropivacaine 0.75% or isotonic saline. The in accordance with the CONSORT statement. The study groups were given 30 ml of ropivacaine or trial was registered at http://www.clinicaltrials.gov saline immediately post-operatively according to (NCT01104883). randomization. Additional boluses of 15 ml of ropi- From August 2010 to March 2011 all patients vacaine 0.75% or saline were administered at 6, 12 undergoing TKA at the two centers were screened and 18 h post-operatively. At 24 h post-operatively, for inclusion. Eligible participants were patients after assessment of pain, morphine consumption, scheduled for primary TKA under spinal anesthe- ambulation ability, and side effects, both the ropi- sia, aged 50–85 years, with an American Society of vacaine and the saline groups received a bolus of Anesthesiologists physical status classification of 15 ml of ropivacaine 0.75%. I–III, and a body mass index of 18–35. Exclusion Intravenous patient-controlled analgesia (PCA) criteria were inability to cooperate, inability to speak was provided with morphine, bolus 2.5 mg, lock-out or understand Danish, allergy to any drug used in time 10 min and no background infusion. If analge- the study, a daily intake of strong opioids (mor- sia was inadequate patients received an additional phine, oxycodone, methadone, fentanyl, ketobemi- bolus of 2.5 mg morphine i.v. until adequate analge- done), alcohol or drug abuse or inability to perform sia was obtained. Additional analgesics consisted of the mobilization test [Timed-Up-and-Go (TUG) oral acetaminophen 1 g and oral ibuprofen 400 mg 15 test ] pre-operatively. administered at 6-h intervals, initiated at 6 h post-operatively. Interventions Ondansetron 4 mg i.v. was administered in the Pre-medication consisted of acetaminophen 1 g case of moderate to severe nausea or vomiting, with orally 1 h before surgery. Spinal anesthesia was supplemental doses of 1 mg, if needed. induced with 2 ml 0.5% hyperbaric bupivacaine at the L3/4 interspace (alternatively at the L2/3 or Outcomes L4/5 interspaces). Sedation with propofol and intra- The primary endpoint was cumulative morphine operative fluid therapy were administered at the consumption during 0–24 h post-operatively. 358 Adductor-canal-blockade for TKA

Secondary endpoints were pain at rest and during numbers, except for the last block, which only con- 45 degrees flexion of the knee, ambulation ability tained five numbers. Upon inclusion into the study assessed with the TUG test, post-operative nausea the participants were assigned consecutive numbers and vomiting (PONV), ondansetron consumption and received the study medication in the corre- and sedation. sponding boxes. All investigators, staff, and patients were blinded Assessment of outcomes to the treatment groups. The randomization key was All patients were tutored by one of the investigators first broken once enrollment of all patients was com- pre-operatively in the visual analog scale (VAS), as pleted and data computed. well as trained in the TUG test and in the use of the PCA system. Statistical analysis Patients were assessed at 2, 4, 8, 24, and 26 h Statistical analyses (based on intention to treat) post-operatively. Recordings made at these time were performed using SPSS 18 (SPSS, Chicago, points included cumulative morphine consumption IL, USA). Data are presented as mean and SD, (0–24 h post-operatively), pain at rest, pain during or with medians and range as appropriate. The 45 degrees flexion of the knee, nausea, vomiting, Kolmogorov–Smirnov test was used to test for nor- ondansetron consumption (0–24 h) and sedation. mality. For VAS pain scores during flexion of the Ambulation ability (TUG test) was assessed twice, at knee and at rest the area under the curve (AUC) 24 and 26 h post-operatively. 2–24 h post-operatively was calculated. The 24-h Pain was evaluated on a VAS with 0 mm = no pain, total morphine consumption, AUC-pain scores, the and 100 mm = worst imaginable pain. Ambulation TUG test at 24 h and the change in the TUG test ability was assessed with the TUG test, a validated scores and the VAS-pain scores (at rest and during 15 test, which measures the number of seconds flexion of the knee) from 24 to 26 h were compared spent to get up from an ordinary armchair, walk a using the independent samples t-test. Side-effects distance of 3 m, turn, walk back to the chair and sit (nausea, number of vomits and sedation) were com- down. All patients used a highwalker with arm pared with the Mann–Whitney U-test for unpaired support as assisting walking aid for the test. Nausea data. For comparison of nausea and sedation, the and sedation were assessed on a four-point scale arithmetic mean scores were calculated by attribut- (0 = no nausea/sedation, 1 = light, 2 = moderate, ing numerical values to the scores from each patient. 3 = severe). Vomiting was assessed as number of Categorical data (ondansetron) were analyzed using vomiting episodes with a volume greater than the chi-squared test. The nature of the hypothesis 10 ml. testing was two-tailed, and P < 0.05 was considered At 26 h post-operatively, patients were assessed statistically significant. The investigators did all sta- for sensibility (sensation of cold) in the saphenous tistical analysis. area at the middle and medial part of the lower leg. Results Sample size Based on previous studies16–18 we estimated a mean A total of 168 patients were approached for partici- morphine consumption of 50 mg (SD 25) during the pation in the study from August 2010 to March 2011. first 24 h post-operatively after TKA. A reduction of Seventy-five patients were recruited and randomly 20 mg in morphine consumption was considered assigned to their treatment group, of these four clinically relevant. With a=0.05 and a power of 90%, patients were excluded after randomization (Fig. 1). 34 patients would be required in each group. To Finally, data from 71 patients were analyzed. The compensate for drop-outs we planned for an inclu- groups were similar with respect to demographics sion of 70 patients. and perioperative data (Table 1). As illustrated in Fig. 2, total morphine consump- Randomization and blinding tion from 0 to 24 h post-operatively was significantly The study medication was prepared by the phar- reduced in the ropivacaine group compared with the macy in identical glass containers and pre-packed in placebo group [40 Ϯ 21 vs. 56 Ϯ 26 mg, respectively boxes, one for each patient. These were consecu- (-27– -5 mg, 95% CI), P = 0.006]. tively numbered according to a computer generated Pain scores during 45 degrees flexion of the knee block randomization list, performed by the phar- (AUC 2–24 h post-operatively) were lower in the macy in a 1 : 1 ratio, each block containing 10 ropivacaine group compared with the placebo 359 M. T. Jenstrup et al.

Fig. 1. Flow diagram of patient distribu- tion. BMI, body mass index.

Table 1 Patient characteristics and perioperative data. Ropivacaine group Placebo group Number of patients 34 37 Sex (male/female) 18/16 19/18 Age (years) 67 (7) 67 (9) Height (cm) 172 (8) 173 (11) Weight (kg) 88 (15) 87 (19) Pre-operative VAS pain at rest (mm) 12 (17) 14 (21) Pre-operative VAS pain at 45 degrees flexion of the knee (mm) 25 (26) 29 (27) Operated side (right/left) 15/19 20/17 Hospital site (Hamlet/Glostrup) 18/16 19/18 Duration of surgery (min) 65 (28) 60 (19) Bleeding (ml) 92 (148) 99 (167) Isotonic sodium chloride (ml) 815 (454) 854 (470) Voluven (ml) 0 (0) 27 (164) Thigh torniquet (yes/no) 33/1 32/5

Values are reported as number of subjects or mean (SD). VAS, visual analog scale.

360 Adductor-canal-blockade for TKA

Fig. 2. Effects of the adductor-canal-blockade on cumulative mor- Fig. 4. Effects of the adductor-canal-blockade on pain at rest. phine consumption. Data are expressed as mean Ϯ SD. Cumulate Visual analog scores (VAS; 0–100 mm, mean Ϯ SD) calculated as morphine consumption from 0 to 24 h post-operatively was signifi- area under the curve (AUC) for the interval 2–24 h post- cantly reduced in the ropivacaine group compared with the placebo operatively. Pain scores at rest were reduced in the ropivacaine group (P = 0.006). group, but this difference did not reach statistical significance (P = 0.058). At 24 h both groups received ropivacaine via the adductor-canal-blockade catheter. From 24 to 26 h post- operatively, pain scores decreased significantly in the saline group compared with the ropivacaine group (P = 0.01).

of ropivacaine) compared with the ropivacaine group, both during flexion of the knee (P < 0.001) and at rest (P = 0.01). Patients in the ropivacaine group performed the TUG test at 24 h post-operatively faster than patients in the placebo group (36 Ϯ 17 vs. 50 Ϯ 29 s, respectively, mean (SD), P = 0.03). This difference disappeared at 26 h post-operatively, 2 h after administration of ropivacaine in both study groups (33 Ϯ 20 vs. 41 Ϯ 27s, respectively, P = 0.21) (Fig. 5). There were no differences between groups with Fig. 3. Effects of the adductor-canal-blockade on pain during 45 regard to nausea (P = 0.12), vomiting (P = 0.47) or degrees flexion of the knee. Visual analog scores (VAS; 0–100 mm, mean Ϯ SD) calculated as area under the curve (AUC) for the sedation (P = 0.15). The number of patients requiring interval 2–24 h post-operatively. Pain scores during 45 degrees ondansetron were reduced in the ropivacaine group flexion of the knee were significantly reduced in the ropivacaine (8/34) vs. the placebo group (19/37), (P = 0.01). group compared with the placebo group (P = 0.01). At 24 h both At 26 h post-operatively, 63/71 patients were groups received ropivacaine via the Adductor-Canal-Blockade tested for sensibility in the saphenous area: 59 catheter. From 24 to 26 h post-operatively, pain scores decreased patients had loss of cold sensation (functional significantly in the saline group compared with the ropivacaine group (P < 0.001). block), and four patients had normal sensation (failed block, all in the placebo group). All US-guided ACBs were performed as described in the Materials and Methods section and group (P = 0.01) (Fig. 3). Pain scores at rest were without any complication registered. Three patients reduced in the ropivacaine group, but this difference were withdrawn during the study: one received an did not reach statistical significance (P = 0.058) erroneously injection of part of the study medication (Fig. 4). From 24 to 26 h post-operatively, pain scores intravenously at 24 h (data from 0 to 24 h included); decreased in the saline group (after administration one developed a crural compartment syndrome and 361 M. T. Jenstrup et al.

in the control group (P = 0.01). A possible explana- tion for this discrepancy might be that while nausea was only assessed at specific time points, the outcome of ondansetron consumption covers the entire time period from 0 to 24 h. At first glance the observed effects on opioid requirements and pain demonstrated in the current study may seem clinically modest. However, all patients in our study received a basic analgesic regimen with acetaminophen, ibuprofen, and PCA morphine. This will obviously blunt the opioid- sparing and pain relieving effect of the ACB per se. Nevertheless, we observed significant differences in several outcomes between the study groups. Further, our results are comparable with those from Fig. 5. Effects of the adductor-canal-blockade on ambulation a recent review of continuous FNB in similar 2 ability, assessed with the Timed-Up-and-Go (TUG) test. Data are patients. Thus, compiled data from that analysis expressed as mean Ϯ SD. Patients in the ropivacaine group per- showed that continuous FNB reduced morphine formed the TUG test at 24 h post-operatively significantly faster consumption during the first 24 h post-operatively than patients in the placebo group (P = 0.03). This difference dis- by 15 mg,2 compared with 16 mg in the present appeared at 26 h post-operatively, 2 h after administration of ropi- study. In addition, continuous FNB reduced pain vacaine via the adductor-canal-blockade catheter in both study 2 groups (P = 0.21). during activity at 24 h by 1.5 cm on a VAS scale, whereas the ACB reduced pain during 45 degrees flexion of the knee at 24 h by 1.9 cm. Neither the 2 was transferred to another hospital for fasciectomy FNB nor the ACB had any significant effect on pain (no data available for analyses); one withdrew his at rest. Importantly, none of the blocks are expected consent at 5 h post-operatively (data from 0 to 4 h to result in complete analgesia, and consequently included). In addition one patient had missing these techniques should be evaluated in combina- values for pain assessments at 26 h, and six patients tion with other analgesics or analgesic methods. had missing values for the test for sensibility. All Notably, the ropivacaine group performed the other patients had complete data set for all assess- TUG test at 24 h post-operatively significantly faster ments at all time points. than the placebo group. While all patients in the ropivacaine group could be mobilized at 24 h post- Discussion operatively, two patients in the placebo group could not, because of pain and discomfort. These two This is the first randomized, placebo-controlled patients were mobilized at 26 h, 2 h after injection of study investigating the effect of high-volume, ropivacaine via the catheter. In the ropivacaine repeated administration of local anesthetic into the group one patient could not perform the TUG test at adductor canal, via a catheter with a midthigh, sub- 26 h post-operatively. This patient reported no pain sartorial approach, in patients undergoing TKA. in the knee, but severe pain in the muscles of the Results showed that an ACB with ropivacaine sig- thigh, provoked during the first TUG test. nificantly reduced 24 h morphine consumption. The ACB is an almost pure sensory block, with the Further, pain during 45 degrees flexion of the knee vastus medialis muscle as the only muscle with was reduced throughout the study (P = 0.01), and potentially affected motor function. Our results ropivacaine administered to the control group at the show that the blockade may enhance early ambula- end of the study significantly reduced pain at rest tion compared with placebo. This is a potentially and during flexion. Moreover, ambulation ability important advantage compared with the FNB as it (TUG test) in patients with the active treatment was has been demonstrated that even a very low dose/ improved compared with placebo (P = 0.03). low volume continuous FNB reduces the strength of Although common, opioid-related side effects such the quadriceps muscle by more than 80% in human as PONV and sedation only demonstrated a trend volunteers.6 towards reduction, but patients with an active ACB Recently, focus has been on the risk of falling asso- required ondansetron less frequently than patients ciated with peripheral nerve blocks for the lower 362 Adductor-canal-blockade for TKA limbs.7–13 Ilfeld et al. reported seven falls in 171 ous infusions. Studies have shown that intermittent patients receiving a peripheral nerve block involv- boluses provide superior analgesia compared with ing the femoral nerve.7 All of these falls occurred in continuous infusions via an epidural catheter.30 the active treatment group showing a probable Although the mechanism is unknown, this phenom- causal relationship between peripheral nerve blocks enon might also be present with peripheral nerve involving the femoral nerve and fall episodes. The blockades. Whether the ACB should be performed quadriceps muscle is essential in mobilization. The as a catheter technique (repeated boluses or continu- ACB leaves three out of the four components of ous infusion) or by a single-shot technique should the quadriceps muscle unblocked, which potentially be subject to further investigation. reduces the risk of falling caused by quadriceps In conclusion, the ACB significantly reduced mor- weakness. Obviously, further studies are needed to phine consumption and pain during 45 degrees validate the effect of ACB on muscle strength. flexion of the knee compared with placebo after In the treatment group we used 0.75% ropivacaine TKA. Furthermore it significantly enhanced ambu- in relatively large volumes to ensure evenly distri- lation ability at 24 h assessed with the TUG test. This bution throughout the adductor canal. With these almost pure sensory block may be a useful analgesic large volumes we cannot rule out a systemic effect adjuvant for acute post-operative pain management of the local anesthetic. However, it should be noted after TKA. The degree of motor blockade, as well as that after injection of ropivacaine 0.75%, 15 ml at the optimal volume and concentration of local anes- 24 h post-operatively, pain scores during flexion thetic, should be subject to further investigation. and at rest in the placebo group were reduced compared with pre-injection values. This decrease Acknowledgements was more pronounced than in the ropivacaine group. This finding validates the significant results The authors gratefully acknowledge the invaluable assistance of the nursing staff at the Orthopaedic Ward and the entire Oper- observed between groups during the first 24 h ating and Recovery room staff at Hamlet Hospital, Frederiks- post-operatively, and is unlikely to be caused by a berg, Denmark and Glostrup Hospital, Glostrup, Denmark. We systemic effect of ropivacaine. The ACB is a novel would also like to thank Copenhagen University Hospital GCP technique and studies are needed to investigate Unit, Bispebjerg Hospital, Denmark, for monitoring the study. Support was provided solely from institutional and depart- the optimal concentration and volume of local anes- mental sources. thetic to be utilized in this block. Conflict of interest: The authors have no conflicts of interest. 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