A radiological cadaveric study of obturator nerve involvement and cranial injectate spread after different approaches to the fascia iliaca compartment block.

Whether the fascia iliaca compartment block (FICB) involves the obturator nerve (ON) remains controversial. Involvement may require that the injectate spreads deep in the cranial direction, and might thus depend on the site of injection. Therefore, the effect of suprainguinal needle insertion with five centimeters of hydrodissection-mediated needle advancement (S-FICB-H) on ON involvement and cranial injectate spread was studied in this radiological cadaveric study. Results were compared with suprainguinal FICB without additional hydrodissection-mediated needle advancement (S-FICB), infrainguinal FICB (I-FICB), and femoral nerve block (FNB). Seventeen human cadavers were randomized to receive ultrasound-guided nerve block with a 40 mL solution of local anesthetic and contrast medium, on both sides. Injectate spread was objectified using computed tomography. The femoral and lateral femoral cutaneous nerves were consistently covered when S-FICB-H, S-FICB or FNB was applied, while the ON was involved in only one of the 34 nerve blocks. I-FICB failed to provide the same consistency of nerve involvement as S-FICB-H, S-FICB or FNB. Injectate reached most cranial in specimens treated with S-FICB-H. Our results demonstrate that even the technique with the most extensive cranial spread (S-FICB-H) does not lead to ON involvement and as such, the ON seems unrelated to FICB. Separate ON block should be considered when clinically indicated.

Anatomical and Radiological Assessments of Injectate Spread Stratified by the Volume of the Pericapsular Nerve Group Block.

BACKGROUND: The pericapsular nerve group (PENG) block was recently suggested as a regional technique for managing acute pain after hip surgery. However, few anatomical studies have confirmed the spread of injectate during the PENG block. This cadaver study aimed to analyze injectate spread to the target nerves during single-injection ultrasound-guided PENG block. METHODS: Ultrasound-guided PENG block with 3 different injectate volumes (10, 20, or 30 mL) was performed in 18 cadavers. Injectate spread by the volume was first evaluated on computed tomography, followed by cadaver dissection. The spread of the dye over the pelvis and lower limb was evaluated. RESULTS: The articular branches of the femoral nerve were stained nearly sufficiently with 20- and 30-mL specimens. The femoral nerve itself was stained simultaneously in six of 12 (50%) 20-mL specimens and 12 of 12 (100%) 30-mL specimens. The accessory obturator nerve was observed only in three (9%) of 36 specimens. The articular branches of the obturator nerve were rarely affected, regardless of injectate volume (1/12, 10 mL specimens; 2/12, 20 mL specimens; 1/12, 30 mL specimens; P > .999). Rather, the obturator nerve was affected. However, the obturator nerve was not stained consistently even with 30 mL of injectate (50%). CONCLUSIONS: After combining the dissection and radiological findings, the single-injection ultrasound-guided PENG blocks with volumes of 10, 20, and 30 mL do not support motor sparing or selective anterior hip capsule innervation in a clinical setting. If early rehabilitation is needed, high-volume PENG block might not be the ideal option, and persisting pain after PENG block might be attributed in part to the lack of obturator nerve articular branches blockade.

Obturator nerve block does not provide analgesic benefits in total hip arthroplasty under multimodal analgesic regimen: a randomized controlled trial.

BACKGROUND AND OBJECTIVES: Although regional analgesia is considered an important component of optimal pain management, use of peripheral nerve blocks for total hip arthroplasty remains controversial. Since the obturator nerve innervates the anteromedial part of the joint capsule, we hypothesized that an obturator nerve block would decrease the opioid consumption after total hip arthroplasty. METHODS: In this single center, prospective, triple blinded study, we randomly allocated 60 patients undergoing total hip arthroplasty under opioid-sparing total intravenous general anesthesia to a preoperative obturator nerve block or a sham block (placebo group) using 20 mL of ropivacaine 0.2% or saline, respectively. All patients received a multimodal analgesic regimen with non-opioid analgesics including periarticular local infiltration analgesia. The primary outcome was the intravenous opioid consumption in the post-anesthesia care unit. RESULTS: Median (IQR) intravenous oxycodone consumption in the post-anesthesia care unit was 4 (2, 7.5) mg in the obturator nerve block group and 3 (0, 4) mg in the placebo group (p=0.05). There were no differences in pain scores between groups in the first 24 hours except at arrival on the surgical ward with significant higher pain scores in the placebo group (p=0.03). The ability to stand up and walk within 24 hours was comparable between groups as was the time to first walk (180 (90, 720) vs 240 (120, 780) min for the obturator nerve block and placebo groups, respectively; p=0.62). CONCLUSIONS: Obturator nerve block did not improve postoperative opioid consumption after total hip arthroplasty performed under general anesthesia with a multimodal analgesic regimen. TRIAL REGISTRATION NUMBER: NCT04085640.

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.

A case report of primary multiple obturator nerve schwannomas.

Primary multiple obturator nerve schwannomas originate from Schwann cells and are extremely rare. Patients with schwannomas are asymptomatic and a retroperitoneal schwannoma is often misdiagnosed as an adnexal mass. In the present study, we describe a 58-year-old woman in whom a right adnexal mass accompanied by endometrial polyp was found incidentally through transvaginal ultrasound. The mass was diagnosed as multiple obturator nerve schwannomas after laparoscopy. Immunohistochemical assay confirmed the schwannomas to be positive for SOX10. To our knowledge, this is the first report to demonstrate a case of multiple schwannomas originating from the obturator nerve and treated by laparoscopic resection.

Ultrasound-guided psoas compartment and sciatic nerve blocks for pain management of hind limb procedures in the alpaca (Vicugna pacos).

Background: Loco-regional anesthetic techniques are considered important in the multimodal approach to analgesia in both human and veterinary medicine. No such techniques are described in the alpaca, bar the use of epidural. This is in part due to the lack of anatomical description for this species. While this limitation exists, the use of ultrasound guidance makes peripheral nerve blocks a viable possibility in the alpaca. Case description: A 12-month-old alpaca was referred for the treatment of a septic left tarso-crural joint. Due to a poor prognosis, amputation of the limb under general anesthesia was performed. Sciatic and psoas compartment blocks were attempted with the ultrasound-guided injection of ropivacaine prior to the start of the procedure. While the femoral nerve was possible to visualize, no obturator nerve was identified. A 5-year old alpaca was also referred for a left hind lateral claw removal, due to a squamous cell carcinoma. The sciatic nerve block was performed prior to the claw amputation under general anesthesia. No changes in heart and respiratory rate, or blood pressure suggestive of nociception, were observed in either of these cases. At the end of both the procedures, the patients experienced uneventful recoveries characterized by the ability to maintain the standing position, interest in food, and normal behavior. Conclusion: This report identifies the ease of performance and the challenges encountered using the ultrasound-guided psoas compartment and sciatic nerve blocks in the alpaca. It is our hope that this report encourages the use of ultrasound-guided loco-regional techniques in this species.

Efecto analgésico del bloqueo PENG (grupo de nervios pericapsulares) en pacientes con fractura de cadera / Analgesic effect of the PENG BLOCK (pericapsular nervous group) in patients with hip fracture

Ultrasound regional blockade emerged that blocks the branches of the femoral nerve, obturator and accessory obturator that innervate the anterior hip capsule, the PENG block (group of pericapsular nerves), which by its Recent description does not have enough evidence in medical practice. To verify the analgesic effect of the PENG block in patients with hip fracture and its analgesic permanence during the first 10 hours after the block in patients admitted with a diagnosis of hip fracture, at the General Interzonal Hospital of Acute "Dr Oscar E Alende "From Mar del Plata, Argentina, in the months of May to November 2019. A prospective descriptive observational study was carried out with a total of 53 patients, hospitalized patients with a diagnosis of hip fracture, with standardized intravenous analgesic scheme and who have not yet undergone hip surgery. Pain was evaluated with the EVA scale (visual analog scale) prior to the blockage, and then at 30 min and 10 hours after the blockade, 15 ml of 1% lidocaine and 15 ml of bupivacaine at 0 were used. 25%, convex or linear ultrasound probe according to patient weight and 100 mm needle. In order to reproduce and evaluate the pain, the patients had a 30º flexion of the hip. Prior to the blockade, 66% of the patients had severe pain and 34% moderate pain, none presented mild pain or absence, both at thirty minutes and ten hours after the blockade, no patient presented severe pain and all patients presented analgesia with a decrease in more than three points on the VAS scale, in some cases reaching a decrease of 10 points on that scale. The PENG block is a regional anesthesia technique that provides very good analgesia to patients with hip fractures, therefore, it is an excellent saving strategy for systemic analgesics. Knowing the analgesia provided by the blockade at 30 min and at 10 h, it could be performed both in the preoperative period for the transfer and mobilization of the patient, as well as in the postoperative period, which could save the use of opioids and decrease hospital stay.

INTRODUCCIÓN La fractura de cadera es una emergencia ortopédica común en ancianos asociada a gran morbimortalidad, una adecuada analgesia regional perioperatoria determina un ahorro en el uso de analgésicos sistémicos. Recientemente, en el año 2018, surgió un nuevo bloqueo regional ecoguiado muy prometedor que bloquea las ramas del nervio femoral, obturador y obturador accesorio que inervan la capsula anterior de la cadera, el bloqueo PENG (grupo de nervios pericapsulares), el cual por su reciente descripción no cuenta con la suficiente evidencia en la práctica médica. OBJETIVOS: Comprobar el efecto analgésico del bloqueo PENG en pacientes con fractura de cadera y su permanencia analgésica durante las 10 primeras horas posteriores al bloqueo en los pacientes internados con diagnóstico de fractura de cadera, en el Hospital Interzonal General de Agudos "Dr. Oscar E Alende" de Mar del Plata, Argentina, en los meses de mayo a noviembre del 2019. MATERIALES Y MÉTODOS: Se realizó un estudio observacional descriptivo prospectivo con un total de 53 pacientes, se incluyeron pacientes internados con diagnóstico de fractura de cadera, con esquema analgésico endovenoso estandarizado y que aún no hayan sido sometido a cirugía de cadera. Se evaluó el dolor con la escala EVA (escala análoga visual) previo al bloqueo, y luego a los 30 min y a las 10 Hs de haber realizado el bloqueo, para este se utilizaron 15 ml lidocaína 1% y 15 ml de bupivacaína al 0,25%, sonda ecográfica convexa o lineal según el peso del paciente y aguja 100 mm. Para reproducir y evaluar el dolor se les realizo a los pacientes una flexión de 30º de la cadera. RESULTADOS: Previo al bloqueo el 66% de los pacientes tuvieron dolor severo y 34% dolor moderado, ninguno presentaba dolor leve o ausencia del mismo, tanto a los treinta minutos como a las diez horas posteriores al bloqueo ningún paciente presento dolor severo y todos los pacientes presentaron analgesia con una disminución en más de tres puntos en la escala de EVA, llegando en algunos casos a una disminución de 10 puntos de dicha escala. CONCLUSIONES: El bloqueo PENG es una técnica de anestesia regional que brinda muy buena analgesia a los pacientes con fractura de cadera, por consiguiente, es una excelente estrategia ahorradora de analgésicos sistémicos. Conociendo la analgesia que brinda el bloqueo a los 30 min y a las 10 h de realizado, se podría realizar dicho bloqueo tanto en el preoperatorio para el traslado y movilización del paciente, como en el post-operatorio, lo que podría ahorrar el uso de opioides y disminuir la estancia hospitalaria.

Obturator Intraneural Ganglion Cysts: Joint Connected and Underdiagnosed.

BACKGROUND: Intraneural ganglion cysts of the obturator nerve are rare. Our aim is to review cases of obturator intraneural ganglion cysts at our institution and those reported in the literature. METHODS: We reviewed all cases evaluated by the senior author. A literature search was performed using the PubMed database and Google Scholar with the following terms: "obturator cyst," "obturator intraneural ganglion cyst," and "obturator intraneural ganglia." All cases underwent a retrospective review. Patient demographic data, including age, sex, and presenting signs and symptoms were recorded. Imaging studies were re-evaluated by 2 musculoskeletal radiologists experienced in the diagnosis of intraneural ganglion cysts. RESULTS: We identified 2 cases of obturator intraneural ganglia at our institution; both were connected to the hip joint. We found 4 cases that were clearly diagnosed as intraneural ganglia in the literature, of which only 1 was recognized by the original authors as being joint connected, but based on our reinterpretation, 3 of 4 were joint connected. An additional 9 cases identified in the literature did not definitely report the nerve-cyst relationship, but based on our reinterpretation, were believed to be intraneural; 8 were joint connected. CONCLUSIONS: We believe that obturator intraneural ganglion cysts adhere to the principles of the unifying articular theory. They arise from the anteromedial hip joint and extend into an articular branch and can reach the parent obturator nerve. Surgery should address the hip disease and/or the articular branch connection. Not appreciating the pathoanatomy of these cysts can lead to persistent or recurrent cysts.

A Case Report of Combined Ultrasound and Fluoroscopic-Guided Percutaneous Radiofrequency Lesioning of the Obturator and Femoral Articular Branches in the Treatment of Persistent Hip Pain in a Pediatric Patient.

Hip denervation comprising radiofrequency lesioning of the obturator and femoral articular branches is used in adults with refractory hip pain who are not surgical candidates. Persistent hip pain occurs infrequently in pediatric patients, and there are limited data on the safety and efficacy of this procedure in a pediatric population. We provide a case report of a successful ultrasound and fluoroscopic-guided hip denervation procedure in an 11-year-old girl with persistent right hip pain after septic arthritis refractory to conservative and surgical management. At an 18-week follow-up, hip denervation provided improvement in pain, mobility, and reduced opioid consumption by 20%.

Pericapsular Nerve Group (PENG) Block for Hip Fracture.

Fascia iliaca block or femoral nerve block is used frequently in hip fracture patients because of their opioid-sparing effects and reduction in opioid-related adverse effects. A recent anatomical study on hip innervation led to the identification of relevant landmarks to target the hip articular branches of femoral nerve and accessory obturator nerve. Using this information, we developed a novel ultrasound-guided approach for blockade of these articular branches to the hip, the PENG (PEricapsular Nerve Group) block. In this report, we describe the technique and its application in 5 consecutive patients.

Gemelli-obturator complex in the deep gluteal space: an anatomic and dynamic study.

OBJECTIVE: To investigate the behavior of the sciatic nerve during hip rotation at subgluteal space. MATERIALS AND METHODS: Sonographic examination (high-resolution ultrasound machine at 5.0-14 MHZ) of the gemelli-obturator internus complex following two approaches: (1) a study on cadavers and (2) a study on healthy volunteers. The cadavers were examined in pronation, pelvis-fixed position by forcing internal and external rotations of the hip with the knee in 90° flexion. Healthy volunteers were examined during passive internal and external hip rotation (prone position; lumbar and pelvic regions fixed). Subjects with a history of major trauma, surgery or pathologies affecting the examined regions were excluded. RESULTS: The analysis included eight hemipelvis from six fresh cadavers and 31 healthy volunteers. The anatomical study revealed the presence of connective tissue attaching the sciatic nerve to the structures of the gemellus-obturator system at deep subgluteal space. The amplitude of the nerve curvature during rotating position was significantly greater than during resting position. During passive internal rotation, the sciatic nerve of both cadavers and healthy volunteers transformed from a straight structure to a curved structure tethered at two points as the tendon of the obturator internus contracted downwards. Conversely, external hip rotation caused the nerve to relax. CONCLUSION: Anatomically, the sciatic nerve is closely related to the gemelli-obturator internus complex. This relationship results in a reproducible dynamic behavior of the sciatic nerve during passive hip rotation, which may contribute to explain the pathological mechanisms of the obturator internal gemellus syndrome.

Anatomic Study of Innervation of the Anterior Hip Capsule: Implication for Image-Guided Intervention.

BACKGROUND AND OBJECTIVES: The purpose of this cadaveric study was to determine the pattern of anterior hip capsule innervation and the associated bony landmarks for image-guided radiofrequency denervation. METHODS: Thirteen hemipelvises were dissected to identify innervation of the anterior hip capsule. The femoral (FN), obturator (ON), and accessory obturator (AON) nerves were traced distally, and branches supplying the anterior capsule documented. The relationships of the branches to bony landmarks potentially visible with ultrasound were identified. RESULTS: The anterior hip capsule received innervation from the FNs and ONs in all specimens and the AON in 7 of 13 specimens. High branches of the FN (originating above the inguinal ligament) were found exclusively in 12 specimens and passed between the anterior inferior iliac spine and the iliopubic eminence. The ONs were innervated exclusively by high branches (proximal to the division), by low branches (from the posterior branch), and by both in 4, 5, and 4 specimens, respectively. The most consistent landmark was the inferomedial acetabulum (radiographic "teardrop"). When present, the AON coursed over the iliopubic eminence before innervating the anterior hip capsule. CONCLUSIONS: Branches of the FNs and ONs consistently provided innervation to the anterior hip capsule. The AON also contributed innervation in many specimens. The relationship of the articular branches from these 3 nerves to the inferomedial acetabulum and the space between the anterior inferior iliac spine and iliopubic eminence may suggest potential sites for radiofrequency ablation.

The Spread of Ultrasound-Guided Injectate From the Adductor Canal to the Genicular Branch of the Posterior Obturator Nerve and the Popliteal Plexus: A Cadaveric Study.

BACKGROUND AND OBJECTIVES: The popliteal nerve plexus contributes to afferent knee-pain conduction. It is mainly formed by genicular branches from the posterior obturator and the tibial nerves, innervating the intra-articular and posterior knee region. A subinguinal obturator nerve block alleviates pain after total knee arthroplasty. Reduced hip adductor motor function could be avoided by a posterior obturator nerve block inside the popliteal fossa.The aim of this study was to evaluate the spread of dye after a distal adductor canal (AC) injection to the popliteal fossa and coloring of the popliteal plexus and the genicular branch of the posterior obturator nerve by dissection. We also assessed the spread of dye into the popliteal fossa after a distal femoral triangle injection. METHODS: Ten milliliters of dye was injected into the distal part of the AC in 10 cadaver sides and into the distal part of the femoral triangle in 3 sides. Dissection was used to assess the spread of the injectate and coloring of the popliteal plexus and the genicular branch of the posterior obturator nerve, as well as the saphenous and medial vastus nerves. RESULTS: The popliteal plexus and the genicular branch of the posterior obturator nerve were dyed in all 10 dissections after AC injections. No dye spread into the popliteal fossa after femoral triangle injections. CONCLUSIONS: Injection of 10 mL of dye into the distal part of the AC spreads into the popliteal fossa and colors the popliteal plexus and the genicular branch of the posterior obturator nerve.

Ultrasound-Guided Obturator Nerve Block: A Focused Review on Anatomy and Updated Techniques.

This review outlines the anatomy of the obturator nerve and the indications for obturator nerve block (ONB). Ultrasound-guided ONB techniques and unresolved issues regarding these procedures are also discussed. An ONB is performed to prevent thigh adductor jerk during transurethral resection of bladder tumor, provide analgesia for knee surgery, treat hip pain, and improve persistent hip adductor spasticity. Various ultrasound-guided ONB techniques can be used and can be classified according to whether the approach is distal or proximal. In the distal approach, a transducer is placed at the inguinal crease; the anterior and posterior branches of the nerve are then blocked by two injections of local anesthetic directed toward the interfascial planes where each branch lies. The proximal approach comprises a single injection of local anesthetic into the interfascial plane between the pectineus and obturator externus muscles. Several proximal approaches involving different patient and transducer positions are reported. The proximal approach may be superior for reducing the dose of local anesthetic and providing successful blockade of the obturator nerve, including the hip articular branch, when compared with the distal approach. This hypothesis and any differences between the proximal ONB techniques need to be explored in future studies.