The Anterior Branch of the Medial Femoral Cutaneous Nerve Innervates Cutaneous and Deep Surgical Incisions in Total Knee Arthroplasty.

Background/Objectives: The intermediate femoral cutaneous nerve (IFCN), the saphenous nerve, and the medial femoral cutaneous nerve (MFCN) innervate the skin of the anteromedial knee region. However, it is unknown whether the MFCN has a deeper innervation. This would be relevant for total knee arthroplasty (TKA) that intersects deeper anteromedial genicular tissue layers. Primary aim: to investigate deeper innervation of the anterior and posterior MFCN branches (MFCN-A and MFCN-P). Secondary aim: to investigate MFCN innervation of the skin covering the anteromedial knee area and medial parapatellar arthrotomy used for TKA. Methods: This study consists of (1) a dissection study and (2) unpublished data and post hoc analysis from a randomized controlled double-blinded volunteer trial (EudraCT number: 2020-004942-12). All volunteers received bilateral active IFCN blocks (nerve block round 1) and saphenous nerve blocks (nerve block round 2). In nerve block round 3, all volunteers were allocated to a selective MFCN-A block. Results: (1) The MFCN-A consistently innervated deeper structures in the anteromedial knee region in all dissected specimens. No deep innervation from the MFCN-P was observed. (2) Sixteen out of nineteen volunteers had an unanesthetized skin gap in the anteromedial knee area and eleven out of the nineteen volunteers had an unanesthetized gap on the skin covering the medial parapatellar arthrotomy before the active MFCN-A block. The anteromedial knee area and medial parapatellar arthrotomy was completely anesthetized after the MFCN-A block in 75% and 82% of cases, respectively. Conclusions: The MFCN-A shows consistent deep innervation in the anteromedial knee region and the area of MFCN-A innervation overlaps the skin area covering the medial parapatellar arthrotomy. Further trials are mandated to investigate whether an MFCN-A block translates into a clinical effect on postoperative pain after total knee arthroplasty or can be used for diagnosis and interventional pain management for chronic neuropathic pain due to damage to the MFCN-A during surgery.

Subpectineal obturator nerve block reduces opioid consumption after hip arthroscopy: a triple-blind, randomized, placebo-controlled trial.

BACKGROUND: Hip arthroscopy causes severe pain during the first few hours in the postoperative care unit. This is probably due to the intraoperative stretching of the hip joint capsule. Pain relief requires high doses of opioids which may prolong recovery and may cause opioid-related adverse events.The majority of hip joint capsule nociceptors are located anteriorly. The obturator nerve innervates the anteromedial part of the hip joint capsule. We hypothesized that a subpectineal obturator nerve block using 15 ml bupivacaine 5 mg/mL with added epinephrine 5 µg/mL would reduce the opioid consumption after hip arthroscopy. METHODS: 40 ambulatory hip arthroscopy patients were enrolled in this randomized, triple-blind controlled trial. All patients were allocated to a preoperative active or placebo subpectineal obturator nerve block. The primary outcome was opioid consumption for the first 3 hours in the postanesthesia care unit. Secondary outcomes were pain, nausea, and hip adductor strength. RESULTS: 34 patients were analyzed for the primary outcome. The mean intravenous morphine equivalent consumption in the subpectineal obturator nerve block group was 11.9 mg vs 19.7 mg in the placebo group (p<0.001). The hip adductor strength was significantly reduced in the active group. No other intergroup differences were observed regarding the secondary outcomes. CONCLUSION: We found a significant reduction in the opioid consumption for patients receiving an active subpectineal obturator nerve block. The postoperative intravenous morphine equivalent reduction the first painful 3 hours was reduced by 40% for patients receiving a subpectineal obturator nerve block in this randomized, triple-blind trial. TRIAL REGISTRATION NUMBER: EudraCT database 2021-006575-42.

Efficacy of iliopsoas plane block for patients undergoing hip arthroscopy: a prospective, triple-blind, randomized, placebo-controlled trial.

BACKGROUND: Intraoperative stretching of the hip joint capsule often generates severe pain during the first 3 hours after hip arthroscopy. The short-lived severe pain mandates high opioid consumption, which may result in adverse events and delay recovery. The femoral nerve nociceptors are located anteriorly in the hip joint capsule. A femoral nerve block reduces pain and opioid demand after hip arthroscopy. It impedes, however, ambulation and home discharge after outpatient surgery. The iliopsoas plane block selectively anesthetizes the femoral sensory nerve branches innervating the hip joint capsule without compromising ambulation. We aimed to assess reduction of opioid consumption after iliopsoas plane block during the short-lived painful postsurgical period of time after hip arthroscopy. METHODS: In a randomized, triple-blind trial, 50 patients scheduled for hip arthroscopy in general anesthesia were allocated to active or placebo iliopsoas plane block. The primary outcome was opioid consumption during the first three postoperative hours in the postanesthesia care unit. Secondary outcomes included pain, nausea, and ability to ambulate. RESULTS: Forty-nine patients were analyzed for the primary outcome. The mean 3-hour intravenous morphine equivalent consumption in the iliopsoas plane block group was 10.4 mg vs 23.8 mg in the placebo group (p<0.001). No intergroup differences were observed for the secondary outcomes during the postoperative follow-up. CONCLUSION: An iliopsoas plane block reduces opioid consumption after hip arthroscopy. The reduction of opioid consumption during the clinically relevant 3-hour postsurgical period of time was larger than 50% for active versus placebo iliopsoas plane block in this randomized, triple-blind trial.

Anatomical considerations for obturator nerve block with fascia iliaca compartment block.

This report reviews the topographical and functional anatomy relevant for assessing whether or not the obturator nerve (ON) can be anesthetized using a fascia iliaca compartment (FIC) block. The ON does not cross the FIC. This means that the ON would only be blocked by an FIC block if the injectate spreads to the ON outside of the FIC. Such a phenomena would require the creation of one or more artificial passageways to the ON in the retro-psoas compartment or the retroperitoneal compartment by disrupting the normal anatomical integrity of the FI. Due to this requirement for an artificial pathway, an FIC block probably does not block the ON.

Anesthesia of the anterior femoral cutaneous nerves for total knee arthroplasty incision: randomized volunteer trial.

BACKGROUND AND OBJECTIVES: For pain relief after total knee arthroplasty (TKA), an injection at the midthigh level may produce analgesia inferior to that of a femoral nerve block as the anterior femoral cutaneous nerves (intermediate femoral cutaneous nerve (IFCN) and medial femoral cutaneous nerve (MFCN)) are not anesthetized. The IFCN can be selectively anesthetized in the subcutaneous tissue above the sartorius muscle and the MFCN by an injection in the proximal part of the femoral triangle (FT). The primary aim was to investigate the area of cutaneous anesthesia in relation to the surgical incision for TKA and anteromedial knee area after intermediate femoral cutaneous nerve blockade (IFCNB) in combination with an injection in the proximal or distal part of the FT (proximal vs distal femoral triangle block (FTB)). METHODS: The study was carried out as two separate investigations: first, dissection of nine cadaver sides to verify a technique for IFCNB; second, a volunteer study with 40 healthy volunteers. The surgical midline incision for TKA was drawn bilaterally. All volunteers received an active distal FTB combined with a placebo proximal FTB on one side and vice versa on the other side. All volunteers were randomized to an active IFCNB on one side and placebo IFCNB on the contralateral side. RESULTS: Identification of IFCN was successful in all cadaver sides. Fifteen out of 20 volunteers had complete anesthesia of the incision line after IFCNB combined with proximal FTB, which was significantly higher compared with proximal FTB alone and with distal FTB+IFCNB. A gap at the anteromedial knee area was present in 2/20 volunteers with proximal FTB compared with 17/20 with distal FTB when all volunteers had active IFCNB. CONCLUSION: Ultrasound-guided blockade of the IFCN and MFCN anesthetize the surgical midline incision and the anteromedial area of the knee relevant for TKA. In contrast, an injection at the midthigh level produces insufficient cutaneous anesthesia not covering the areas of interest. TRIAL REGISTRATION NUMBER: EudraCT: 2018-004986-15.

Randomized trial of ultrasound-guided superior cluneal nerve block.

BACKGROUND AND OBJECTIVES: The superior cluneal nerves originate from the dorsal rami of primarily the upper lumbar spinal nerves. The nerves cross the iliac spine to innervate the skin and subcutaneous tissue over the gluteal region. The nerves extend as far as the greater trochanter and the area of innervation may overlap anterolaterally with the iliohypogastric and the lateral femoral cutaneous (LFC) nerves. A selective ultrasound-guided nerve block technique of the superior cluneal nerves does not exist. A reliable nerve block technique may have application in the management of postoperative pain after hip surgery as well as other clinical conditions, for example, chronic lower back pain. In the present study, the primary aim was to describe a novel ultrasound-guided superior cluneal nerve block technique and to map the area of cutaneous anesthesia and its coverage of the hip surgery incisions. METHODS: The study was carried out as two separate investigations. First, dissection of 12 cadaver sides was conducted in order to test a novel superior cluneal nerve block technique. Second, this nerve block technique was applied in a randomized trial of 20 healthy volunteers. Initially, the LFC, the subcostal and the iliohypogastric nerves were blocked bilaterally. A transversalis fascia plane (TFP) block technique was used to block the iliohypogastric nerve. Subsequently, randomized, blinded superior cluneal nerve blocks were conducted with active block on one side and placebo block contralaterally. RESULTS: Successful anesthesia after the superior cluneal nerve block was achieved in 18 of 20 active sides (90%). The area of anesthesia after all successful superior cluneal nerve blocks was adjacent and posterior to the area anesthetized by the combined TFP and subcostal nerve blocks. The addition of the superior cluneal nerve block significantly increased the anesthetic coverage of the various types of hip surgery incisions. CONCLUSION: The novel ultrasound-guided nerve block technique reliably anesthetizes the superior cluneal nerves. It anesthetizes the skin posterior to the area innervated by the iliohypogastric and subcostal nerves. It improves the anesthetic coverage of incisions used for hip surgery. Among potential indications, this new nerve block may improve postoperative analgesia after hip surgery and may be useful as a diagnostic block for various chronic pain conditions. Clinical trials are mandated. TRIAL REGISTRATION NUMBER: EudraCT, 2016-004541-82.

An Obturator Nerve Block does not Alleviate Postoperative Pain after Total Hip Arthroplasty: a Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: A substantial group of patients suffer from moderate to severe pain following elective total hip arthroplasty (THA). Due to the complex innervation of the hip, peripheral nerve block techniques can be challenging and are not widely used. Since the obturator nerve innervates both the anteromedial part of the joint capsule as well as intra-articular nociceptors, we hypothesized that an obturator nerve block (ONB) would decrease the opioid consumption after THA. METHODS: Sixty-two patients were randomized to receive ONB or placebo (PCB) after primary THA in spinal anesthesia. Primary outcome measure was opioid consumption during the first 12 postoperative hours. Secondary outcome measures included postoperative pain score, nausea score and ability to ambulate. RESULTS: Sixty patients were included in the analysis. Mean (SD) opioid consumption during the first 12 postoperative hours was 39.9 (22.3) mg peroral morphine equivalents (PME) in the ONB group and 40.5 (30.5) mg PME in the PCB group (p=0.93). No difference in level of pain or nausea was found between the groups. Paralysis of the hip adductor muscles in the ONB group reduced the control of the operated lower extremity compared with the PCB group (p=0.026). This did, however, not affect the subjects' ability to ambulate. CONCLUSIONS: A significant reduction in postoperative opioid consumption was not found for active versus PCB ONB after THA. TRIAL REGISTRATION NUMBER: NCT03064165 and 2017-000068-14.