Groin Pain Beyond the Hip: How Anatomy Predisposes to Injury as Visualized by Musculoskeletal Ultrasound and MRI

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1 Musculoskeletal Imaging Pictorial Essay randon et al. Groin Pain eyond the Hip Musculoskeletal Imaging Pictorial Essay Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved Catherine J. randon 1 Jon. Jacobson David Fessell Qian Dong Yoav Morag Gandikota Girish David Jamadar randon CJ, Jacobson J, Fessell D, et al. Keywords: pelvis, MRI, trauma, ultrasound DOI: /JR Received pril 30, 2010; accepted after revision pril 18, ll authors: Department of Radiology, University of Michigan, 1500 E Medical Center Dr, TC-2910, nn rbor, MI ddress correspondence to C. J. randon (catbrand@umich.edu). CME This article is available for CME credit. See for more information. JR 2011; 197: X/11/ merican Roentgen Ray Society Groin Pain eyond the Hip: How natomy Predisposes to Injury as Visualized by Musculoskeletal Ultrasound and MRI OJECTIVE. The purpose of this article is to show ultrasound and MRI examples of the normal anatomic structures and their resulting modifications from trauma and disease. CONCLUSION. lthough groin pain from hip pathology is well recognized, lower anterior abdominal wall and anterior pelvis structures can be interrelated sources of pain. I n this article, particular attention will be given to the major role the pubic symphysis plays in anchoring the anterior abdominal wall, inguinal region, and the adductor group and to how the inguinal region functions as a transition zone between the torso, lower extremities, and genital area. High-risk activities, such as hockey, soccer, and childbirth as well as sex differences predisposing to different rates of hernia formation will be discussed. The Pubic Symphysis The pubic symphysis fulfills multiple functions beyond that of a joint constructed to withstand shifting weight transfers. It anchors the torso with insertion of the rectus abdominis and oblique muscles, the thigh with adductor insertions, and the ligaments of the inguinal region. These insertions are within centimeters of each other, often with interwoven insertional fibers that reinforce the joint capsule. This aponeurosis is formed anteriorly and inferiorly from blended fibers of the abdominis rectus, adductor longus, adductor brevis, and gracilis tendons. The pubic arcuate ligament inferiorly and posteriorly is formed in part from adductor longus and gracilis fibers. The superior surface of the joint capsule is buttressed by the superior pubic ligament [1 7]. The joint itself is formed by hyaline cartilage lining the two pubic bodies with a central fibrocartilage disk. The differential diagnosis of groin pain is complicated by the similar clinical presentations of acute and chronic injury patterns. These patterns that can be better defined by imaging and include arthropathies, adductor and rectus tendinopathies, stress fractures, and groin hernia formation. cute trauma can disrupt the pubic symphysis, whether from direct impact such as a motor vehicle collision with a capsule tear extending into the adjacent muscle (Fig. 1) or from muscle contractions during childbirth with a torn disk and capsule (Fig. 2). Osteitis pubis, paraarticular bone marrow edema, osteophytes, and bony sclerosis can be the result of chronically destabilized pubic symphysis from remote injury to tendinous and aponeurosis insertions [1, 3 6] (Fig. 3). Stresses generated in the lower extremity by quick turns and accelerations, as in soccer, can produce focal zones of increased force with resulting tendinopathy. The adductor longus tendon is frequently injured in both acute and chronic overuse as visualized by MRI [1 7] and ultrasound [8] (Figs. 4 6). The adductor tendon can shear the pubic aponeurosis off the capsule and bone (often referred to as sports hernia) (Figs. 5 and 5C), possibly from asymmetric antagonistic actions of the rectus abdominis and adductor muscle groups [3, 4]. When chronic repetitive forces exceed the cortical bone strength, fatigue-type stress fractures can occur at the pubic symphysis [6] (Fig. 5D). lthough ultrasound can show tendon, muscle, and aponeurosis abnormalities about the pubic symphysis as well as cortical irregularities, MRI allows depiction of the deep and intraosseous pathology. The Groin and Inguinal Region The inguinal region functions as a transition zone from the abdomen to the upper thigh with related femoral and obturator canals and to the external genital regions with 1190 JR:197, November 2011

2 Groin Pain eyond the Hip Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved the inguinal canal and inguinal triangle. True hernias can occur in the inguinal, femoral, and obturator regions and can produce general groin pain. Stress-induced abdominal wall hernias related to athletic activities, the clinically described sports hernias or clinical athletic pubalgia, often can be shown by MRI to have patterns of subtle aponeurotic injury, either midline or along the lateral fibers at the level of the external inguinal ring [1, 5]. These injuries may produce ligamentous laxity at the inguinal canal [4, 6]. Ultrasound with its dynamic capabilities can distinguish true hernias with motion of abdominal contents including fat into the inguinal canal or other transition sites from areas of focal clinical tenderness [8, 9]. Inguinal Canal and Triangle The inguinal anatomy is complex but is divided into the inguinal canal, which is the path to the genital region with the spermatic cord or round ligament (Fig. 7) and the inguinal triangle (or Hesselbach triangle), which is the posterior wall of the inguinal canal and adjacent lower abdominal wall (Fig. 7). The inguinal ligament is the aponeurosis of the external oblique muscle extending from the anterior superior spine of the iliac crest to the anterior lateral margin of the pubic bone. The inguinal canal is formed in the medial half of the ligament (Fig. 7). Femoral and Obturator Canals Narrow openings allow the femoral (Fig. 8) and obturator vessels and nerves to go from the abdomen into the upper thigh (Fig. 9). The femoral and obturator anatomy is not as complex as the inguinal canal and triangle, but hernia formations in these areas are often overlooked sources of pain. Inguinal Hernia Inguinal hernias, especially indirect inguinal hernias in men, are common, accounting for more than 50% of all hernias. They can be clinically occult sources of groin pain. The two classic types of inguinal hernias correspond to inguinal canal and triangle. The indirect hernia slides down the narrow inguinal canal originating lateral to the epigastric vessels (Figs ). The direct hernia pushes the broad surface of the transversalis fascia forward medial to the epigastric vessels (Fig. 13). Dynamic Valsalva motion on ultrasound helps to distinguish hernias from normal wall movement [8, 9] (Figs. 12 and 13). Other Hernias Femoral hernias account for 2 4% of all adult groin hernias; primary femoral hernia encompasses 1% of repairs in men and 23% for women [10]. Women have more femoral hernias (Fig. 14) because their pelvises are broader, with larger femoral rings [6, 11]. Femoral hernias, with a narrower neck, are more likely than inguinal hernias to have complications requiring bowel resection (23% compared with 5%) [10, 12]. The obturator hernia is an infrequent hernia (1 2%) most common in elderly women who may present with vague hip and groin pain (Fig. 15). ecause the obturator nerve runs though the tight canal, a hernia can compress the nerve, producing pain radiating from the groin to the knee (the Howship- Romberg sign) [13 15], which can be present in 15 50% of cases [14, 15]. Obturator hernias have the highest morbidity and mortality rates among groin hernias, ranging from 12% to 70% [13, 15]. If there is clinical concern for bowel obstruction in any hernia, CT is the modality for evaluation [14]. Conclusions Musculoskeletal ultrasound and MRI evaluation of groin and anterior pelvis anatomic relationships can show shared structural ties and patterns of injury resulting in groin pain. Ultrasound can image tendinopathies and with its dynamic capabilities can show true hernia formation at multiple sites in the groin. References 1. Shortt CP, Zoga C, Kavanagh EC, Meyers WC. natomy, pathology and MRI findings in the sports hernia. Semin Musculoskelet Radiol 2008; 12: Robinson P, arron D, Parsons W, Grainger J, Schilders EM, O Connor PJ. dductor-related groin pain in athletes: correlation of MR imaging with clinical findings. Skeletal Radiol 2004; 33: rennan D, O Connell MJ, Ryan M, et al. Secondary cleft sign as a marker of injury in athletes with groin pain: MR imaging appearance and interpretation. Radiology 2005; 235: Cunningham PM, rennan D, O Connell M, MacMahon P, O Neill P, Eustace S. Patterns of bone and soft-tissue injury at the symphysis pubis in soccer players: observations at MRI. JR 2007; 188:864; [web]w291 W Zoga C, Kavanagh EC, Omar IM, et al. thletic pubalgia and the sports hernia : MR imaging findings. Radiology 2008; 247: Zajick DC, Zoga C, Omar IM, Meyers WC. Spectrum of MRI findings in clinical athletic pubalgia. Semin Musculoskelet Radiol 2008; 12: Robinson P, Salehi R, Grainger, et al. Cadaveric and MRI study of the musculotendinous contributions to the capsule of the symphysis pubis. JR 2007; 188:1306; [web]w440 W Robinson P. Ultrasound of groin injury. In: Mc- Nally EG, ed. Practical musculoskeletal ultrasound. Philadelphia, P: Elsevier Churchill Livingstone, 2005: Jamadar D, Jacobson J, Morag Y, et al. Sonography of inguinal region hernias. JR 2006; 187: Dahlstrand U, Wollert S, Nordin P, et al. Emergency femoral hernia repair: a study based on a national register. nn Surg 2009; 249: Schuenke M, Schulte E, Schumacher U. tlas of anatomy: general anatomy and musculoskeletal system. Stuttgart, Germany: Thieme, Nilsson H, Stylianidis G, Haapamaki M, et al. Mortality after groin hernia surgery. nn Surg 2007; 245: Rodriguez-Hermosa JI, Codina-Cazador, Maroto-Genover, et al. Obturator hernia: clinical analysis of 16 cases and algorithm for its diagnosis and treatment. Hernia 2008; 12: Strange CD, irkemeir KL, Sincleair ST, Shepherd JR. typical abdominal hernias in the emergency department: acute and non-acute. Emerg Radiol 2009; 16: Sun HP, Chao YP. Preoperative diagnosis and successful laparoscopic treatment of incarcerated obturator hernia. Hernia 2010; 14: JR:197, November

3 randon et al. Fig year-old woman 5 months after motor vehicle collision (anterior compression injury) with pubic bone and symphysis injury. Coronal proton density weighted MR image with fat saturation shows pubic symphyseal diastasis as well as torn fibrocartilage disk and capsule, with tendon tear extending into right adductor muscles insertion (arrow). Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman 1 month after complex vaginal delivery (distractive force) with pubic bone and symphysis injury. Coronal proton density weighted MR image with fat saturation shows persistent symphyseal diastasis as well as torn fibrocartilage disk and capsule (arrow), with bilateral bone marrow edema. Fig year-old woman who is avid soccer player with history of years of groin and pubic pain (repetitive injury) and multiple groin muscle injuries. xial proton density weighted MR image with fat saturation shows osteitis pubis, with bilateral intense bone marrow edema of pubis bones (arrows) with sclerosis and osteophyte formation. Fig year-old woman with anterior pelvic pain from exercise program (chronic overuse)., xial proton density weighted fat saturation MR image shows bilateral adductor longus tendinopathy (arrows) at insertion on anterior inferior pubic bone and symphyseal capsule., Ultrasound of left adductor longus (long axis) shows abnormal hypoechoic thickening of involved tendon (arrow) JR:197, November 2011

4 Groin Pain eyond the Hip Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved C Fig year-old man who is trail and long distance runner (overuse injury) with pubic and groin pain., xial proton density weighted fat saturation MR image shows edema at right adductor longus tendon origin (arrow) on anterior inferior pubic tubercle. and C, Coronal () and sagittal (C) proton density weighted fat saturation MR images show bilateral tears of capsule and large aponeurotic separation (arrowheads) extending across anterior inferior pubic symphysis. D, Coronal proton density weighted fat saturation MR image obtained 8 months after initial presentation shows stress fracture along right anterior pubic symphysis (arrow) still present. D Fig year-old man with general groin pain. Ultrasound image long-axis to adductor longus shows full-thickness tear with retraction (arrowhead) from pubic attachment site (arrow). JR:197, November

5 randon et al. Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old man with normal inguinal region. C, Coronal proton density weighted MR image () and illustrations ( and C) show inguinal canal that extends from deep or internal ring (arrow) at epigastric vessels to superficial or external ring (asterisk). Close association of inguinal canal and rectus abdominis insertion on pubic symphysis can be seen. Medial fibers of inguinal ligament attach to pubic tubercle and joint capsule along lateral margin of rectus abdominis at level of superficial ring (arrowhead). Inguinal triangle (yellow triangle, ) is medial and superior to canal. C Fig year-old woman with normal femoral canal. Coronal proton density weighted MR image shows femoral canal (arrow) medial to femoral vein and inferior to inguinal ligament (arrowhead). Normally, there are lymph nodes and small amount of fat in femoral canal JR:197, November 2011

6 Groin Pain eyond the Hip Fig year-old woman with fat-filled obturator canal. xial proton density weighted MR image shows obturator canal (arrowhead) and its neurovascular bundle deep in relation to inguinal canal, which in this case has herniated fat (black arrow). Note region of femoral canal (white arrow) and superior pubic ramus. Pectineus muscle is anterior to obturator canal. Fat within inguinal ring is common finding and may be asymptomatic. Correlation with clinical presentation can prevent inappropriate herniorrhaphies. Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with fat-containing indirect inguinal hernia. C, Sagittal proton density weighted MR images of groin from lateral to medial show round ligament (white arrow) within fat-filled inguinal canal from deep internal ring () with epigastric vessels (arrowhead, ) to superficial ring (C). Transversalis fascia (arrowhead, and C) forms deep wall of canal. Inguinal canal inserts on anterior pubic aponeurosis and pubic ramus via inguinal ligament (black arrow, and C). Fig year-old man with left indirect inguinal hernia. Ultrasound in panoramic transverse plane shows well-developed rectus abdominis muscles and normal deep inguinal ring on right (solid arrow). Peritoneal fat (open arrow) is seen adjacent to deep inguinal ring lateral to epigastric vessels (arrowhead), which entered into deep ring with Valsalva maneuver (not shown) and was symptomatic. C JR:197, November

7 randon et al. Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved C Fig year-old man with right indirect inguinal hernia. D, Oblique ultrasound images long-axis to inguinal canal at rest () and corresponding illustration () and during Valsalva maneuver (C) and corresponding illustration (D) show hernia (arrows, C and D) entering inguinal canal at deep inguinal ring lateral to inferior epigastric vessels (arrowhead). Fig year-old man with right direct inguinal hernia. and, xial ultrasound images over inguinal triangle at rest () and with Valsalva maneuver () show transversalis fascia (dashed line) and adjacent epigastric vessels (arrowhead). Note echogenic fat (arrows) in that pushes transversalis fascia anteriorly toward skin, representing direct inguinal hernia. D 1196 JR:197, November 2011

8 Groin Pain eyond the Hip Downloaded from by on 12/30/17 from IP address Copyright RRS. For personal use only; all rights reserved Fig year-old woman with left femoral hernia. and, Ultrasound images in transverse plane at rest () and with Valsalva maneuver () show normal fat (arrowhead) medial to femoral vein within femoral canal. Note in, peritoneal fat (arrows) entering femoral canal between femoral vein and normal fat. FOR YOUR INFORMTION This article is available for CME credit. See for more information. Fig year-old woman with right obturator hernia. and, Sagittal () and coronal () proton density weighted MR images show hernia (arrow). Obturator hernias have high morbidity and mortality rates because of small-bowel obstruction. JR:197, November