Abstract. Adductor canal block (ACB) is an effective analgesic alternative to femoral nerve block after total knee arthroplasty (TKA). The aim of the present study was to investigate whether addition of dexamethasone to ropivacaine for ACB is able to prolong analgesia and reduce pain. Study participants were randomized into groups receiving ACB with either 0.5% ropivacaine + normal saline (control group; n=93) or 0.5% ropivacaine + 8 mg dexamethasone (dexamethasone group; n=93). All patients were subjected to identical peri-operative management. Patients were assessed for the duration of analgesia by the return of pinprick sensation. A numerical rating scale, ranging from 0 to 10, was used to assess post-operative pain at 6, 12, 18, 24 and 48 h. Opioid use was recorded. Serum C-reactive protein and interleukin-6 levels were measured at 3, 6, 12, 24 and 48 h after surgery. The results revealed that the duration of sensory block was significantly longer in the dexamethasone group (23.42±3.35 vs. 14.67±2.96 h in control group, P<0.05). The dexamethasone group also had significantly lower pain scores at 6, 12, 18 and 24 h after surgery (all P<0.001), and at 48 h, pain was comparable in the two groups. Reduction in post-operative pain was associated with a decrease in serum C-reactive protein.Morphine use in the first 24 h after surgery was also lower in the dexamethasone group (4.23±1.80 vs. 8.42±2.44 mg in control group, P<0.05). In conclusion, addition of dexamethasone to ropivacaine for ACB was able to prolong the duration of analgesia and decreased early post-operative pain following TKA.

Abstract. Ultrasound-guided interscalene brachial plexus blockade (IBPB) has a relatively high success rate in shoulder surgery; however, whether multiple injections are superior to a single injection (SI) is currently unknown. In the present study, ultrasound-guided SI and triple-injection (TI) IBPBs were compared in a prospective randomized trial. A total of 111 patients undergoing arthroscopic shoulder surgery and presenting with an American Society of Anesthesiologists physical status grading of I-II were randomly allocated to receive IBPB with 15 ml of 1% ropivacaine as a SI or TI. Performance time, procedure-related pain scores, success rate and prevalence of complications were recorded. The distribution of sensory and motor block onset in the radial, median, ulnar and axillary nerves were assessed every 5 min until 30 min post-local anesthetic injection. The duration of sensory and motor blocks were also assessed. A significantly longer performance time was recorded in the TI group (P<0.001). No significant difference was observed in success rate (91% in TI vs. 88% in SI) 30 min post-injection, and the prevalence of complications and procedure-related pain were similar between the two groups. Sensory and motor blocks of the ulnar nerve in the TI group were significantly faster and more successful compared with the SI group at all time points (P<0.041). It was also observed that sensory and motor blocks in the TI group were prolonged compared with the SI group (P<0.041). In conclusion, the TI method exhibited a faster time of onset and resulted in a more successful blockade of the ulnar nerve. TI method may be a more effective approach for IBPB in a clinical setting. IntroductionBlockade of the brachial plexus through an interscalene approach has a relatively high success rate in shoulder surgery (1-3). Ultrasound imaging of the brachial plexus between the anterior and middle scalene muscles is feasible (4), and it has been documented that use of ultrasound improves the success rate and reduces the prevalence of complications (5). Furthermore, the site of injection may affect the spread of local anesthetic (LA) (6), and a number of studies comparing different approaches for nerve blocks have documented that multiple injections of LA around the nerve result in a higher prevalence of success and a shorter time of onset compared with LA deposition at a single location (7-9). Furthermore, the present authors have previously observed that triple injection (TI) is necessary if LA is deposited inside the paraneural sheath, and that the paraneurium ʻentrapsʼ LA molecules, thereby ensuring circumferential spread around the interscalene brachial plexus nerve (7). Therefore, ultrasound-guided TI may increase the efficacy and quality of interscalene brachial plexus blocks (IBPBs).In the present study, a prospective, randomized, observerblinded trial was conducted to compare the efficacy and safety of single injection (SI) and TI methods of IBPB for arthroscopic shoulder surgery. The primary aims were to compare the on...