Effect of combining peri-hamstring injection or anterior obturator nerve block on the analgesic efficacy of adductor canal block for anterior cruciate ligament reconstruction: a randomised controlled trial.

BACKGROUND: Pain after anterior cruciate ligament reconstruction (ACLR) with autologous hamstring graft can be attributed to both arthroscopic surgery and the graft donor site. This study investigated whether donor site pain control was superior with the addition of either peri-hamstring injection or anterior division obturator nerve block in comparison with adductor canal block (ACB) alone. METHODS: Patients scheduled to undergo knee arthroscopy with ACLR using a graft from the ipsilateral hamstring were randomised to one of three groups. All patients received ACB and multimodal analgesia. Subjects in Group H received peri-hamstring local anaesthetic injection while subjects in Group O received an anterior division of the obturator nerve block, and subjects in Group C served as a control group (ACB alone). RESULTS: In 105 subjects undergoing ACLR, there was no significant difference between groups H, O, and C for the primary outcome of pain on movement as assessed by numerical rating scale (NRS) on knee flexion at 2 h after operation (P=0.11). There was no difference in NRS at any time point in the first 48 h after operation, nor was there a difference in oxycodone consumption between the three groups at 24 h (P=0.2). Worst knee pain was initially at the graft donor site in all three groups, which transitioned to anterior knee pain after 12 h. CONCLUSIONS: The addition of ultrasound-guided peri-hamstring injection or anterior division of obturator nerve block to ACB did not result in a significant reduction in pain or opioid consumption after ACLR with ipsilateral hamstring graft. CLINICAL TRIAL REGISTRATION: NCT01868282.

Ultrasound-guided lateral-medial transmuscular quadratus lumborum block for analgesia following anterior iliac crest bone graft harvesting: a clinical and anatomical study.

BACKGROUND: The anterior iliac crest (AIC) is one of the most common sites for harvesting autologous bone, but the associated postoperative pain can result in significant morbidity. Recently, the transmuscular quadratus lumborum block (TQL) has been described to anesthetize the thoraco-lumbar nerves. This study utilizes a combination of cadaveric models and clinical case studies to evaluate the dermatomal coverage and analgesic utility of TQL for AIC bone graft donor site analgesia. METHODS: Ten ultrasound-guided TQL injections were performed in five cadaver specimens using a lateral-to-medial transmuscular approach. Twenty mL of 0.5% methylcellulose was injected on each side after ultrasound confirmation of the needle tip ventral to the quadratus lumborum muscle (QLM). Cranio-caudal and medial-lateral extent of the dye spread in relation to musculoskeletal anatomy and direct staining of the thoraco-lumbar nerves were recorded. Following the anatomical findings, continuous catheter TQL blocks were performed in four patients undergoing ankle surgery with autologous AIC bone graft. The dermatomal anesthesia and postoperative analgesic consumption were recorded. RESULTS: In the anatomical component of the study, 9/10 specimens showed a lateral spread anterior to the transversalis fascia and medially between the QLM and psoas major muscle. Direct staining of the branches of the T12, L1, and L2 nerves was noted ventral to the QLM, while variable staining of the T9-T11 nerves was seen laterally in the transversus abdominis plane and the transversalis fascia. The vertical spread of injectate anterior to the QLM was T12 to the iliac crest (n = 5/10) and L1 to the iliac crest (n = 4/10). In the four patients who received TQL, the T9-L2 dermatomal anesthesia correlated with the injectate spread seen in the cadavers and provided effective analgesia at the bone graft donor site. CONCLUSION: Ultrasound-guided TQL injections consistently cover the thoraco-lumbar innervation relevant to the AIC graft donor site. The injectate spread seen in anatomical dissections correlated with the dermatomal anesthesia clinically. The TQL has the potential to provide reliable analgesia for patients undergoing AIC bone graft harvesting.

Neurological injury following peripheral nerve blocks: a narrative review of estimates of risks and the influence of ultrasound guidance.

BACKGROUND: Peripheral nerve injury or post-block neurological dysfunction (PBND) are uncommon but a recognized complications of peripheral nerve blocks (PNB). A broad range of its incidence is noted in the literature and hence a critical appraisal of its occurrence is needed. OBJECTIVE: In this review, we wanted to know the pooled estimates of PBND and further, determine its pooled estimates following various PNB over time. Additionally, we also sought to estimate the incidence of PBND with or without US guidance. EVIDENCE REVIEW: A literature search was conducted in six databases. For the purposes of the review, we defined PBND as any new-onset sensorimotor disturbances in the distribution of the performed PNB either attributable to the PNB (when reported) or reported in the context of the PNB (when association with a PNB was not mentioned). Both prospective and retrospective studies which provided incidence of PBND at timepoints of interest (>48 hours to <2 weeks; >2 weeks to 6 weeks, 7 weeks to 5 months, 6 months to 1 year and >1 year durations) were included for review. Incidence data were used to provide pooled estimates (with 95% CI) of PBND at these time periods. Similar estimates were obtained to know the incidence of PBND with or without the use of US guidance. Additionally, PBND associated with individual PNB were obtained in a similar fashion with upper and lower limb PNB classified based on the anatomical location of needle insertion. FINDINGS: The overall incidence of PBND decreased with time, with the incidence being approximately 1% at <2 weeks' time (Incidence per thousand (95% CI)= 9 (8; to 11)) to approximately 3/10 000 at 1 year (Incidence per thousand (95% CI)= 0. 3 (0.1; to 0.5)). Incidence of PBND differed for individual PNB with the highest incidence noted for interscalene block. CONCLUSIONS: Our review adds information to existing literature that the neurological complications are rarer but seem to display a higher incidence for some blocks more than others. Use of US guidance may be associated with a lower incidence of PBND especially in those PNBs reporting a higher pooled estimates. Future studies need to standardize the reporting of PBND at various timepoints and its association to PNB.

Core outcome set for peripheral regional anesthesia research: a systematic review and Delphi study.

BACKGROUND/IMPORTANCE: There is heterogeneity among the outcomes used in regional anesthesia research. OBJECTIVE: We aimed to produce a core outcome set for regional anesthesia research. METHODS: We conducted a systematic review and Delphi study to develop this core outcome set. A systematic review of the literature from January 2015 to December 2019 was undertaken to generate a long list of potential outcomes to be included in the core outcome set. For each outcome found, the parameters such as the measurement scale, timing and definitions, were compiled. Regional anesthesia experts were then recruited to participate in a three-round electronic modified Delphi process with incremental thresholds to generate a core outcome set. Once the core outcomes were decided, a final Delphi survey and video conference vote was used to reach a consensus on the outcome parameters. RESULTS: Two hundred and six papers were generated following the systematic review, producing a long list of 224 unique outcomes. Twenty-one international regional anesthesia experts participated in the study. Ten core outcomes were selected after three Delphi survey rounds with 13 outcome parameters reaching consensus after a final Delphi survey and video conference. CONCLUSIONS: We present the first core outcome set for regional anesthesia derived by international expert consensus. These are proposed not to limit the outcomes examined in future studies, but rather to serve as a minimum core set. If adopted, this may increase the relevance of outcomes being studied, reduce selective reporting bias and increase the availability and suitability of data for meta-analysis in this area.

Recommendations for anatomical structures to identify on ultrasound for the performance of intermediate and advanced blocks in ultrasound-guided regional anesthesia.

Recent recommendations describe a set of core anatomical structures to identify on ultrasound for the performance of basic blocks in ultrasound-guided regional anesthesia (UGRA). This project aimed to generate consensus recommendations for core structures to identify during the performance of intermediate and advanced blocks. An initial longlist of structures was refined by an international panel of key opinion leaders in UGRA over a three-round Delphi process. All rounds were conducted virtually and anonymously. Blocks were considered twice in each round: for "orientation scanning" (the dynamic process of acquiring the final view) and for "block view" (which visualizes the block site and is maintained for needle insertion/injection). A "strong recommendation" was made if ≥75% of participants rated any structure as "definitely include" in any round. A "weak recommendation" was made if >50% of participants rated it as "definitely include" or "probably include" for all rounds, but the criterion for strong recommendation was never met. Structures which did not meet either criterion were excluded. Forty-one participants were invited and 40 accepted; 38 completed all three rounds. Participants considered the ultrasound scanning for 19 peripheral nerve blocks across all three rounds. Two hundred and seventy-four structures were reviewed for both orientation scanning and block view; a "strong recommendation" was made for 60 structures on orientation scanning and 44 on the block view. A "weak recommendation" was made for 107 and 62 structures, respectively. These recommendations are intended to help standardize teaching and research in UGRA and support widespread and consistent practice.

International consensus on anatomical structures to identify on ultrasound for the performance of basic blocks in ultrasound-guided regional anesthesia.

There is no universally agreed set of anatomical structures that must be identified on ultrasound for the performance of ultrasound-guided regional anesthesia (UGRA) techniques. This study aimed to produce standardized recommendations for core (minimum) structures to identify during seven basic blocks. An international consensus was sought through a modified Delphi process. A long-list of anatomical structures was refined through serial review by key opinion leaders in UGRA. All rounds were conducted remotely and anonymously to facilitate equal contribution of each participant. Blocks were considered twice in each round: for "orientation scanning" (the dynamic process of acquiring the final view) and for the "block view" (which visualizes the block site and is maintained for needle insertion/injection). Strong recommendations for inclusion were made if ≥75% of participants rated a structure as "definitely include" in any round. Weak recommendations were made if >50% of participants rated a structure as "definitely include" or "probably include" for all rounds (but the criterion for "strong recommendation" was never met). Thirty-six participants (94.7%) completed all rounds. 128 structures were reviewed; a "strong recommendation" is made for 35 structures on orientation scanning and 28 for the block view. A "weak recommendation" is made for 36 and 20 structures, respectively. This study provides recommendations on the core (minimum) set of anatomical structures to identify during ultrasound scanning for seven basic blocks in UGRA. They are intended to support consistent practice, empower non-experts using basic UGRA techniques, and standardize teaching and research.

Spread of dye injectate in the distal femoral triangle versus the distal adductor canal: a cadaveric study.

BACKGROUND AND OBJECTIVES: The nerve to vastus medialis (NVM) supplies sensation to important structures relevant to total knee arthroplasty via a medial parapatellar approach. There are opposing findings in the literature about the presence of the NVM within the adductor canal (AC). The objective of this cadaveric study is to compare the effect of injection site (distal femoral triangle (FT) vs distal AC) on injectate spread to the saphenous nerve (SN) and the NVM. METHODS: Four unembalmed fresh-frozen cadavers acted as their own control with one thigh receiving 20 mL of dye injected via an ultrasound-guided injection in the distal FT while the other thigh received an ultrasound-guided injection in the distal AC. A standardized dissection took place 1 hour later to observe the extent of staining to the NVM and SN in all cadaver thigh specimens. RESULTS: In all specimens where the injectate was introduced into the distal FT, both the SN and NVM were stained. In contrast, when the dye was administered in the distal AC only the SN was stained. CONCLUSIONS: Our findings suggest that an injection in the distal AC may be suboptimal for knee analgesia as it may spare the NVM, while an injection in the distal FT could provide greater analgesia to the knee but may result in undesirable motor blockade from spread to the nerve to vastus intermedius.

Hybrid Blocks for Total Knee Arthroplasty: A Technical Description.

INTRODUCTION: This narrative review article aims to examine current evidence of knee innervation in order to develop a technique of targeting pure sensory innervation of the knee joint without compromising motor function. METHODS: A literature review of knee innervation was performed to gain an anatomic understanding of terminal sensory branches of the relevant target nerves (femoral, obturator, sciatic, and lateral femoral cutaneous). RESULTS: Pure sensory block of the knee joint is challenging due to important contributions from themuscular innervation close to the joint and the variability of nerves afferents contained within and around the adductor canal. CONCLUSION: On the basis of this anatomic knowledge we describe an ultrasound-guided 3-injection hybrid technique that represents a balance between preserving adequate motor power while still providing analgesia in a simple method.

Determination of ED50 and ED95 of 0.5% Ropivacaine in Adductor Canal Block to Produce Quadriceps Weakness: A Dose-Finding Study.

BACKGROUND AND OBJECTIVES: Adductor canal block (ACB) is popular for knee analgesia because of its favorable effect on quadriceps strength. The aim of this study was to find the minimum volume of local anesthetic, which can be injected into the ACB that would result in quadriceps weakness. METHODS: This nonrandomized study used an up-and-down sequential allocation design. Twenty-six patients scheduled to undergo arthroscopic knee surgery received an ultrasound-guided ACB preoperatively. The initial volume of ropivacaine 0.5% injected was 30 mL, which was subsequently increased or decreased by 2 mL, depending on whether the previous subject had a 30% reduction in quadriceps function. The minimum effective volume in 50% of patients was determined using Dixon-Massey up-and-down method. The effective volume in 95% of patients was then calculated using probit transformation. RESULTS: The ED50 (minimum effective anesthetic volume in 50% of the subjects) needed for a 30% decrease in quadriceps power was 46.5 mL (95% confidence interval, 45.01-50.43 mL), and estimated ED95 (minimum effective anesthetic volume in 95% of the subjects) was 50.32 mL (95% confidence interval, 48.66-67.26 mL). The local anesthetic volume injected correlated with degree of quadriceps weakness at 20 minutes postblock (P < 0.001) and in the postanesthesia recovery unit (P = 0.032). CONCLUSIONS: Significant quadriceps weakness is unlikely when clinically representative volumes of 0.5% ropivacaine is used for ACB performed using sonographic landmarks. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov, identifier NCT02541552.

Ultrasound-Guided Motor-Sparing Knee Blocks for Postoperative Analgesia Following Total Knee Arthroplasty: A Randomized Blinded Study.

BACKGROUND: Pain following total knee arthroplasty (TKA) is often severe and can inhibit rehabilitation. Motor-sparing analgesic techniques such as periarticular infiltrations and adductor canal blocks have been popularized for knee analgesia since they preserve motor strength and permit early mobilization. Our primary objective was to compare the duration of analgesia from motor-sparing blocks with that of a standard periarticular infiltration. We used the time to first rescue analgesia as the end point. METHODS: We randomized 82 patients scheduled for elective TKA to receive either the preoperative motor-sparing block (0.5% ropivacaine, 2.5 µg/mL of epinephrine, 10 mg of morphine, and 30 mg of ketorolac) or intraoperative periarticular infiltration (0.3% ropivacaine, 2.5 µg/mL of epinephrine, 10 mg of morphine, and 30 mg of ketorolac). For the motor-sparing block, we modified the ultrasound-guided adductor canal block by combining it with a lateral femoral cutaneous nerve block and posterior knee infiltration. The patients, surgeons, anesthetists administering the blocks, and outcome assessors all remained blinded to group allocation. Our primary outcome was duration of analgesia (time to first rescue analgesia). Secondary outcomes included quadriceps strength, function, side effects, satisfaction, and length of hospital stay. RESULTS: The duration of analgesia was significantly longer (mean difference, 8.8 hours [95% confidence interval = 3.98 to 13.62], p < 0.01) for the motor-sparing-block group (mean [and standard error], 18.1 ± 1.7 hours) compared with the periarticular infiltration group (mean, 9.25 ± 1.7 hours). The infiltration group had significantly higher scores for pain at rest for the first 2 postoperative hours and for pain with knee movement at 2 and 4 hours. There were no significant differences between groups with regard to any other secondary outcomes. CONCLUSIONS: In patients undergoing a TKA, a motor-sparing block provides longer analgesia than periarticular infiltration with retention of quadriceps muscle strength, function, patient satisfaction, and a short hospital stay. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.