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Concept: Iliopsoas


Previous studies have compared muscle activity between different types of sit-ups and curl-ups. However, few have examined exercises used by the armed forces or investigated the influence of exercise duration on muscle activation. The aim of this study was to compare abdominal and hip flexor activity between the style of sit-up used by the British Army and four variations of a curl-up, at the start, middle and end of a 2 min exercise period. Surface electromyograms (EMGs) were recorded from the upper and lower rectus abdominis, external oblique, transversus abdominis/internal oblique, and the rectus femoris (RF) of 23 British Army personnel. Isometric maximal voluntary contractions were used to normalize integrated EMGs to allow them to be compared between exercises. Curl-ups with arms crossed and feet restrained produced the highest integrated EMG in all of the abdominal muscles (p<0.05). Feet restrained sit-ups and curl-ups also resulted in significantly higher activity in the RF than non-restrained versions of the curl-up (p<0.001). The significant increase observed in muscle activity between the start and the end of the exercises (p<0.001) was deemed to be in response to a reduction in force producing capacity of existing motor units. The RF experienced the greatest increase during exercises that activated the muscle the most; i.e. sit-ups and curl-ups with feet restrained (p<0.001). Previous research has indicated that such exercises produce high shear and compressive forces in the lower back, which can be injurious. Thus, if an organisation wishes to assess the endurance of abdominal muscles, rather than hip flexors, then curl-ups without restraint of the feet should be performed instead of exercises in which the feet are restrained.

Concepts: Muscle, Electromyography, Human anatomy, Flexion, Rectus femoris muscle, Hip flexors, Iliopsoas, British Army


The skeletal anatomy of the hip provides two main locations for impingement: abnormal contact between the acetabulum and femur (femoroacetabular impingement) or between the ischium and femur (ischiofemoral impingement). We report a case of bilateral ischiofemoral impingement in a patient with hereditary multiple exostoses. The association of exostoses and femoral metaphyseal widening resulted in the narrowing of the ischiofemoral spaces. Pain was improved on the left side by resection of the ischial exostosis.

Concepts: Skeletal system, Hip, Pelvis, Iliopsoas, Ilium, Hereditary multiple exostoses, Exostosis, Ischium


BACKGROUND: Damage to the hip can occur due to impingement or instability caused by anatomic factors such as femoral and acetabular version, neck-shaft angle, alpha angle, and lateral center-edge angle (CEA). The associations between these anatomic factors and how often they occur in a painful hip are unclear but if unaddressed might explain failed hip preservation surgery. QUESTIONS/PURPOSES: We determined (1) the influence of sex on the expression of impingement-related or instability-related factors, (2) the associations among these factors, and (3) how often both impingement and/or instability factors occur in the same hip. METHODS: We retrospectively reviewed a cohort of 170 hips (145 patients) undergoing MR arthrography of the hip for any reason. We excluded 58 hips with high-grade dysplasia, Perthes' sequelae, previous surgery, or incomplete radiographic information, leaving 112 hips (96 patients). We measured femoral version and alpha angles on MR arthrograms. Acetabular anteversion, lateral CEA, and neck-shaft angle were measured on pelvic radiographs. RESULTS: We observed a correlation between sex and alpha angle. Weak or no correlations were observed between the other five parameters. In 66% of hips, two or more (of five) impingement parameters, and in 51% of hips, two or more (of five) instability parameters were found. CONCLUSIONS: Patients with hip pain frequently have several anatomic factors potentially contributing to chondrolabral damage. To address pathologic hip loading due to impingement and/or instability, all of the anatomic influences should be known. As we found no associations between anatomic factors, we recommend an individualized assessment of each painful hip. LEVEL OF EVIDENCE: Level III, prognostic study. See Instructions for Authors for a complete description of levels of evidence.

Concepts: Physician, Pain, Hip, Pelvis, Sartorius muscle, Human anatomy, Iliopsoas, Obturator internus muscle


This study aimed to describe a suitable acoustic window to facilitate access to the sciatic and femoral nerves in calves and to study the effects of their blockade with local anaesthetics. The neuroanatomical and ultrasound (US) study was performed on the cadavers of 10 calves, and the effects of 2% lidocaine with epinephrine (0.2 mL/kg) were determined in five healthy calves. The sciatic nerve in the cadavers was easily visualised as a hyperechoic band distal to the femoral greater trochanter and caudal to the femoral shaft. The femoral nerve in the cadavers was not easily identified, and was visualised as a hyperechoic oval structure situated immediately medial to the psoas major muscle and lateral to the femoral artery. The sciatic nerve was stained by methylene blue, injected under US guidance, in 9/10 cases, and the femoral nerve was stained in 6/10 cases. Sciatic nerve blockade under US guidance produced adduction of the limb with metatarsophalangeal joint flexion, while the femoral nerve blockade produced reduced weight bearing. The sciatic nerve blockade produced a reduced response to the noxious stimulus, mainly in the phalanges, proximal and distal metatarsus, tarsus and tibia and, following the femoral nerve blockade, in the medial subarea of the femur. However, femoral nerve blockade produced a more variable degree of blockade. In conclusion, US -guided anaesthetic blockade of the sciatic nerve in calves may be considered for surgery in the distal pelvic limb, although further studies are necessary to determine its clinical application.

Concepts: Anesthesia, Sartorius muscle, Nerve, Local anesthetic, Iliopsoas, Nerves of the lower limb and lower torso, Lumbar plexus, Anterior compartment of thigh


Hip flexor injuries account for one third of acute groin injuries; however, little is known about specific injury characteristics. The aims of this study was to describe acute hip flexor injuries using magnetic resonance imaging (MRI) in athletes with acute groin pain, and to compare specific muscle injuries with reported injury situations. Male athletes with acute groin pain were prospectively and consecutively included during 3 sports seasons. MRI was performed within 7 days of injury using a standardized protocol and a reliable assessment approach. All athletes with an MRI confirmed acute hip flexor muscle injury were included. 156 athletes presented with acute groin pain of which 33 athletes were included, median age 26 y (range 18-35). There were 16 rectus femoris, 12 iliacus, 7 psoas major, 4 sartorius, and 1 tensor fascia latae injury. Rectus femoris injuries primarily occurred during kicking (10) and sprinting (4), whereas iliacus injuries most frequently occurred during change of direction (5). In 10 (63%) rectus femoris injuries tendinous injury was observed. The iliacus and psoas major injuries were mainly observed at the musculotendinous junction (MTJ), and two included tendinous injury. We have illustrated specific injury locations within these muscles, which may be relevant for the clinical diagnosis and prognosis of these injuries. Most proximal rectus femoris injuries included tendinous injury. In contrast, distinct acute iliacus and psoas injuries predominantly occurred at the MTJ. Only the iliacus or psoas major were injured during change of direction, whereas rectus femoris injuries occurred primarily during kicking and sprinting. This article is protected by copyright. All rights reserved.

Concepts: Magnetic resonance imaging, Hip, Sartorius muscle, Flexion, Extension, Hip flexors, Iliopsoas, Psoas major muscle


A broad pelvis is characteristic of most, if not all, pre-modern hominins. In at least some early australopithecines, most notably the female Australopithecus afarensis specimen known as “Lucy,” it is very broad and coupled with very short lower limbs. In 1991, Rak suggested that Lucy’s pelvic anatomy improved locomotor efficiency by increasing stride length through rotation of the wide pelvis in the axial plane. Compared to lengthening strides by increasing flexion and extension at the hips, this mechanism could avoid potentially costly excessive vertical oscillations of the body’s center of mass (COM). Here, we test this hypothesis. We examined 3D kinematics of walking at various speeds in 26 adult subjects to address the following questions: Do individuals with wider pelves take longer strides, and do they use a smaller degree of hip flexion and extension? Is pelvic rotation greater in individuals with shorter legs, and those with narrower pelves? Our results support Rak’s hypothesis. Subjects with wider pelves do take longer strides for a given velocity, and for a given stride length they flex and extend their hips less, suggesting a smoother pathway of the COM. Individuals with shorter legs do use more pelvic rotation when walking, but pelvic breadth was not related to pelvic rotation. These results suggest that a broad pelvis could benefit any bipedal hominin, but especially a short-legged australopithecine such as Lucy, by improving locomotor efficiency, particularly when carrying an infant or traveling in a foraging group with individuals of varying sizes. Anat Rec, 300:739-751, 2017. © 2017 Wiley Periodicals, Inc.

Concepts: Hip, Human anatomy, Flexion, Extension, Iliopsoas, Australopithecus afarensis, Hominina, Australopithecus


Barbell back squats are a popular exercise for developing lower extremity strength and power. However, this exercise has potential injury risks, particularly to the lumbar spine, pelvis and hip joint. Previous literature suggests heel wedges as a means of favourably adjusting trunk and pelvis kinematics with the intention of reducing such injury risks. Yet no direct biomechanical research exists to support these recommendations. Therefore, the purpose of this study was to examine the effects of heel wedges compared to barefoot on minimally loaded barbell back squats. Fourteen trained male participants performed a barbell back squat in bare feet or with their feet raised bilaterally with a 2.5cm wooden block while 3D kinematics, kinetics and electromyograms were collected. The heel wedge condition elicited significantly less forward trunk flexion angles at peak knee flexion, and peak external hip joint moments (p<0.05) compared to barefoot conditions. However, no significant differences were observed between conditions for trunk and pelvis angle differences at peak knee flexion (p>0.05). Lastly, no peak or root mean square differences in muscle activity were elicited between conditions (p>0.05). Our results lend support for the suggestions provided in literature aimed at utilizing heel wedges as a means of reducing excessive forward trunk flexion. However, the maintenance of a neutral spine, another important safety factor, is not affected by the use of heel wedges. Therefore, heel wedges may be a viable modification for reduction of excessive forward trunk flexion, but not for reduction in relative trunk-pelvis flexion during barbell back squats.

Concepts: Knee, Hip, Sartorius muscle, Root mean square, Flexion, Extension, Iliopsoas, Semimembranosus muscle


The purpose of the present study was to examine the effects of stabilization training on trunk muscularity and physical performances in youth male soccer players aged 12 - 13 yrs (n = 28). The subjects allocated to training (TG, n = 16) performed a stabilization exercise program consisting of 5 exercises (elbow-toe, elbow-heel, side-bridge, modified one-legged squat, and bent-knee push-up) 4 times per week anda training program specific to soccer 6 times per week, whilethe others (CON, n = 12) conducted the soccer training only for 6 months. Before and after the intervention, the cross-sectional areas (CSAs) of five muscles (rectus abdominus, oblique, psoas major, quadratus lumborum, and erector spinae) were determined using magnetic resonance imaging. Furthermore, peak torques during hip extension and flexion at 1.05 rad/s, heights of squatand countermovement jumps, and time taken to sprint 15 m were also measured. After 6 months, both groups significantly increased the CSAs of the five muscle groups (TG: 4.4 - 13.4%, CON: 5.5 - 10.9%) and improved sprint time (TG: -1.4%, CON: -1.6%), without significant effect of group, but only TG significantly increased the heights of squat(5.0%) and countermovement (6.8%) jumps. In addition, a greater increase in hip extension torque was found in TG (40.8%) than in CON (17.4%). The current results indicate that, at least in early adolescent soccer players, adding stabilization exercise to soccer training cannot increase the trunk muscularity but it will improve hip extensor strength and vertical jump performance.

Concepts: Muscle, Magnetic resonance imaging, Knee, Muscular system, Flexion, Extension, Iliopsoas, Rectus abdominis muscle


Femoroacetabular impingement (FAI) is an abnormality of the femoral head or acetabulum that leads to an increased incidence of cartilaginous injury in the hip. Femoroacetabular impingement has been associated with several structural abnormalities, including osteitis pubis and hip flexor dysfunction. The authors propose that, additionally, FAI may lead to increased damage of the hamstring tendon due to the additional stress placed on the tendon from the limited range of motion of the hip. The authors conducted a retrospective matched-pair study with the magnetic resonance imaging and magnetic resonance arthrography images of 40 patients' hamstrings with FAI and 45 age-matched controls. Images were identified and reviewed by 2 musculoskeletal radiologists for various signs of hamstring tendon pathology. Fisher’s exact test and an odds ratio were used to assess for a difference in the occurrence of hamstring tendon pathology in the FAI patient cohort compared with the age-matched controls. The results showed a statistically significant increase in the occurrence of hamstring tendon pathology in the FAI patient cohort compared with the age-matched controls (P<.001). The odds ratio for hamstring tendon pathology in a subject with confirmed FAI vs control subjects was 8.30 (95% confidence interval, 3.20-21.5), indicating a significant increase in the risk of developing hamstring tendon pathology among patients with FAI (P<.001). This study suggests that there may be an increased occurrence of hamstring tendon pathology in patients with FAI. The kinetic chain of motion, where restricted rotation at the hip joint increases the stress on the hamstring tendons, leading to damage, may explain this increase. [Orthopedics. 2017; 40(6):e1086-e1091.].

Concepts: Magnetic resonance imaging, Pelvis, Ronald Fisher, Flexion, Fisher's exact test, Rectus femoris muscle, Hamstring, Iliopsoas


Little research has examined the rates and patterns of hip flexor or hip adductor strains in student-athletes in the National Collegiate Athletic Association (NCAA).

Concepts: Hip, Flexion, Iliopsoas