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Entrapment of the obturator nerve is a little recognized and rarely taught cause of pelvic and groin/thigh/knee pain. In the pelvis, the obturator nerve can mimic pudendal neuralgia, hip pathology, groin strain, and claudication.
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... and L4, which join within the psoas muscle to form the ON (Table 48.2), as opposed to the femoral nerve, which is formed by the posterior divisions of the ventral rami of those same nerves. Rarely, the entire ON can be positioned posterior to the psoas muscle [34]. The ON then travels over the pelvic brim at the level of the sacroiliac joint ( Fig. 48.2), curving anterior inferiorly along the lateral pelvic wall through a fibro-osseous tunnel [3]. It is the only nerve from the lumbar plexus (Chap. 49), which does not innervate any of the intrapelvic structures. The ON passes into the obtura- tor foramen through a fibro-osseous tunnel (the obturator canal), which is formed superiorly ...
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... [3]. It is the only nerve from the lumbar plexus (Chap. 49), which does not innervate any of the intrapelvic structures. The ON passes into the obtura- tor foramen through a fibro-osseous tunnel (the obturator canal), which is formed superiorly by the obturator sulcus of the pubic bone and inferiorly by the internal and external obturator muscles (Fig. 48.3) [35]. Within the tunnel, the nerve splits into two main branches (an anterior branch and a posterior branch), as well as a branch to the external obtura- tor muscle (which crosses the obturator artery), and then exits through the obturator tunnel to enter the thigh. Kumka [35] noted that the ON could bifurcate within the pelvic cav- ...
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... has been associ- ated with obturator palsy [10]. Litwiller et al. [14] studied various lithotomy positions and found that abduction to greater than 30° without concomitant hip flexion increased strain on the obturator nerve, both in its pelvic segment and the anterior branch. Several authors [6,7] have described an obturator tunnel syndrome ( Fig. 48.4). Bradshaw and McCoy [3] described a fascial entrapment of the obturator in the adductor compartment, induced by exercise, confirmed by anatomic dissection [40]. Bradshaw and McCoy [3] also suggested that the male predomi- nance of this condition may be related to anatomy; males have higher iliac crests, a smaller transverse diameter ...
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... Obturator Nerve Entrapment: Pelvic gests but does not prove obturator pathology, since this reflex is not always present, even in healthy people [28]. There may be tenderness to deep palpation in the adductor canal ( Fig. 48.5), as well as increased pain when the nerve is stretched from extension and/or lateral leg movement [4]. A pectineus stretch (where the patient actively externally rotates and abducts the hip) will stretch the obturator nerve [36]; pain may also be reproduced with internal rotation of the flexed hip against resistance (obturator sign) ( ...
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... Fig. 48.5), as well as increased pain when the nerve is stretched from extension and/or lateral leg movement [4]. A pectineus stretch (where the patient actively externally rotates and abducts the hip) will stretch the obturator nerve [36]; pain may also be reproduced with internal rotation of the flexed hip against resistance (obturator sign) ( Fig. 48.6) [37]. This test is also used on the right side to look for ...
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... and McCoy [3] noted that several of the patients in their series had symptoms of inguinal hernia prior to the development of medial thigh weakness, and they proposed the possibility of a mechanical entrapment. Entrapment of the ON by the external obturator muscle (see Fig. 48.4) may cause a persistent pathology. Kassolik et al. [52] describe the use of massage of the obturator and piriformis muscles to treat ON ...
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... et al. [55] introduced a "three-in-one" anesthesia injection ( Fig. 48.7), designed to anesthetize the femoral, lat- eral femoral cutaneous, and obturator nerves at the same time. The ON can be blocked either proximal or distal to the division into the anterior and posterior branches. Proximally, only one injection is necessary, while after the division, it is necessary to injection both nerve ...
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... standard landmark-guided ON injection involves posi- tioning the patient supine, with the leg slightly abducted and externally rotated; the needle is placed 2 cm caudad and 2 cm lateral to the pubic tubercle, advancing the needle onto the inferior border of superior pubic ramus and then dropping into the obturator canal [56] (Fig. 48.8), with or without a ...
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... fluoroscopy to aid the needle placement for an ON injection involves the fluoroscopic visualization of the superior and inferior pubic rami. The patient is placed supine, and the inferior portion of the obturator foramen is identified. A peripheral nerve stimulator can help to identify the nerve on the inferior pubic ramus (Fig. 48.9). Lateral femoral cutaneous nerve Fig. 48.7 Location of needle for a "3-in-1" injection (Image by Springer) The hip joint is innervated by sensory branches of the obturator nerve as well as the femoral nerves (Chap. 56). For diagnostic ON injections of the hip joint, the patient is placed supine, and the needle is placed just medial to ...
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... needle placement for an ON injection involves the fluoroscopic visualization of the superior and inferior pubic rami. The patient is placed supine, and the inferior portion of the obturator foramen is identified. A peripheral nerve stimulator can help to identify the nerve on the inferior pubic ramus (Fig. 48.9). Lateral femoral cutaneous nerve Fig. 48.7 Location of needle for a "3-in-1" injection (Image by Springer) The hip joint is innervated by sensory branches of the obturator nerve as well as the femoral nerves (Chap. 56). For diagnostic ON injections of the hip joint, the patient is placed supine, and the needle is placed just medial to the femoral artery, below the inguinal ...
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... hip joint, the patient is placed supine, and the needle is placed just medial to the femoral artery, below the inguinal ligament; the needle tip is then directed under fluoroscopy to the inferior junction of the ischium and pubis, where the "teardrop" landmark is made up of the wall of the acetabulum, the lesser pelvis, and the acetabular notch (Fig. ...
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... thigh slightly externally rotated. The first technique involves scanning laterally from the pubic tubercle until the three muscle layers (adductor longus, adductor brevis, and adductor magnus) were identified, moving the probe in a medial/lateral or proximal/distal direc- tion to find the anterior and posterior divisions of the obtura- tor nerve (Fig. 48.10). In the second technique, the femoral artery/vein/nerve is identified at the femoral crease, and the probe is moved medially toward the pubis to visualize the obturator nerve, which, unlike other nerves, appears flat instead of ...
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... with US. They described a "trian- gle," with the superior pubic ramus as the superior border, the pectineus muscle as the anterior border, and the external obturator as the posterior border. They then used eight volun- teers to confirm that the structures could be identified on live patients; they were able to identify the ON in 12 out of 16 Fig. 48.10 Top green arrow marks the superficial branch of the obturator nerve, below the inguinal ligament. Needle injecting the deep branch of the obturator nerve, also marked by green arrow. FA femoral artery. Femoral vein compressed (Image courtesy of Agnes Stogicza, MD) groins. This was followed by ON injections under US guid- ance in 15 ...
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... laterally and inferiorly to the tubercle. After saline with epinephrine infiltration, the 12-gauge catheter is carefully and gently advanced to the inferior border of the ramus. If done blindly, hitting the edge of the ramus will confirm depth. If done under fluoroscopy, the catheter can be directed to just below the inferior border of the ramus (Fig. 48.11). Kim and Ferrante [60] reported cryoneuroablation of the obturator nerve for the treatment of adductor spasticity and obturator neuropathy. To treat spastic- ity, this is one of the few times that motor stimulation for localization is appropriate. Adduction of the thigh at low volt- ages (0.5-1 mV) will confirm position. Spastic ...
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... several days later. The ON was identified at the junction of the inferior ischium and the pubis (see section "Fluoroscopy- Guided Technique" for details of placement). Sensory stimu- lation resulted in groin and thigh pain; after negative motor stimulation, the site was lesioned at 90 °C for 90 s. The femo- ral sensory branch was also lesioned (Fig. 48.12). Eight patients had >50 % pain relief at a 6-month follow-up. Locher et al. [64] dissected the articular branches of the obturator nerve in 20 cadavers and compared the fluoroscopic and MRI images. They concluded that multiple lesions were necessary. Stone and Matchett [41] reported on the use of a combined ultrasound and fluoroscopic ...
Citations
The obturator nerve (ON) arises from the lumbar plexus and provides both sensory and motor innervation to the thigh. The ON entrapment, also known as obturator tunnel syndrome, is not commonly diagnosed or considered and can present as groin, pelvic, and/or lower extremity pain, weakness with leg adduction and sensory loss in the medial thigh. ON injections have utility in diagnosing and treating a wide variety of pelvic, hip, and groin pains. This chapter discusses the anatomy of the ON, ON procedures, possible complications and ways to avoid them. ON blocks should be performed under strict aseptic conditions to prevent the risk of infection. To avoid needle contamination by gravity‐dependent gel flow, in case of inferomedial US‐guided insertion in the inguinal crease, and to facilitate the transducer ergonomy along the visual axis, a lateral‐to‐medial approach, such as the one described by Lin et al. is recommended.
The anatomy of the innervation of the hip joint is described. Nerve block of the nerves to the hip joint is described. Confounding clinical situations such as incisional pain after hip arthroplasty and symptoms of “sciatica” are discussed. The technical approaches to denervation of the hip joint are described and illustrated. The results of hip denervation are presented.
