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Concept: Psoas major muscle


BACKGROUND CONTEXT: The lateral transpsoas approach to interbody fusion of the lumbar spine (lateral lumbar interbody fusion [LLIF]) with recombinant human bone morphogenetic protein-2 (BMP-2) augmentation has been increasingly performed in recent years. Potential side effects and adverse sequelae of BMP-2 in the acute setting remain to be fully elucidated. PURPOSE: To review the literature for reports of complications related to BMP-2 implantation in lumbar spinal surgery and present a case of a contralateral psoas muscle seroma after LLIF with BMP-2 implantation. STUDY DESIGN: Case report and literature review. METHODS: The PubMed database was searched for articles related to adverse events to BMP-2 in lumbar spinal surgery. We report the case of a 57-year-old woman who underwent routine right-sided transpsoas approach for LLIF with the use of BMP-2 at our institution and developed a left-sided psoas muscle fluid accumulation 2 weeks postoperatively. RESULTS: No reports of complications contralateral to an LLIF approach attributable to an inflammatory response to BMP-2 were identified in the English literature. In the presented patient, a large (4.2×6.5×2.7 cm) left-sided sterile intramuscular psoas fluid collection was seen on a magnetic resonance imaging study obtained on postoperative day 14. At a 6-month follow-up, left-sided L5 radiculopathy resulting in 4/5 foot drop was confirmed by electromyography. The patient reported here represents the only case of a contralateral psoas seroma with suspected association to BMP-2 utilization in LLIF encountered at our institution. CONCLUSIONS: A serous psoas muscle fluid accumulation after BMP-2 implantation may rarely occur contralateral to the surgical approach for LLIF. Further characterization of complications related to BMP-2 implantation after lumbar spinal surgery will help guide preoperative informed decision making and the management of this unusual postoperative adverse event.

Concepts: Medical terms, Lumbar vertebrae, Nuclear magnetic resonance, Vertebral column, Magnetic resonance imaging, Report, Adverse event, Psoas major muscle


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


To investigate the effects of dietary crude protein (CP) restriction on muscle fiber characteristics and key regulators related to protein deposition in skeletal muscle, a total of 18 growing-finishing pigs (62.30 ± 0.88 kg) were allotted to 3 groups and fed with the recommended adequate protein (AP, 16 % CP) diet, moderately restricted protein (MP, 13 % CP) diet and low protein (LP, 10 % CP) diet, respectively. The skeletal muscle of different locations in pigs, including longissimus dorsi muscle (LDM), psoas major muscle (PMM) and biceps femoris muscle (BFM) were collected and analyzed.

Concepts: Nutrition, Muscle, Cardiac muscle, Myosin, Longissimus, Lumbar plexus, Psoas major muscle, Psoas minor muscle


The aim of this study was to investigate sarcopenia as a novel predictor for mortality and sepsis after living donor liver transplantation (LDLT), and to evaluate the effect of early enteral nutrition in patients with sarcopenia. A total of 204 patients with preoperative CT within 1 month before living-donor liver transplantation were retrospectively evaluated. The lengths of the major and minor axes of the psoas muscle were simply measured at the caudal end of the third lumbar vertebra, and the area of the psoas muscle was calculated. Lower than the 5 percentile of the healthy donors' psoas muscle area of each gender was defined as sarcopenia. Ninety-six of all the 204 patients (47.1%), 58.3% (60 of 103) in male, and 35.6% (36 of 101) in female patients were diagnosed as sarcopenia. Sarcopenia was independently and significantly associated with overall survival, with a 2-fold higher risk of death in patients with sarcopenia compared to those without (HR; 2.06, p = 0.047). Sarcopenia was an independent predictor of post-operative sepsis (HR = 5.31, p = 0.009). Other independent predictors were younger recipient age (p < 0.001) and higher body mass index (p = 0.02). Early enteral nutrition within 48 hours after LDLT was performed in 24.2% in 2003 - 2007 and 100% in 2008 - 2011, and the incidence of postoperative sepsis in patients with sarcopenia (n = 96) was 28.2% (11/39) in the group of 2003 - 2007 and 10.5% (6/57) in the group of 2008 - 2011 (p = 0.03). Sarcopenia is an independent predictor of mortality and sepsis after LDLT. The incidence of postoperative sepsis reduced even in patients with sarcopenia after applying a routine early enteral nutrition. Liver Transpl , 2013. © 2013 AASLD.

Concepts: Glucose, Obesity, Lumbar vertebrae, Liver, Glycogen, Body mass index, Predictor, Psoas major muscle


We performed bilateral transmuscular quadratus lumborum blocks in six cadavers using iodinated contrast and methylene blue. Computed tomography imaging was performed in four cadavers and anatomical dissection was completed in five. This demonstrated spread to the lumbar paravertebral space in 63% of specimens, laterally to the transversus abdominis muscle in 50% and caudally to the anterior superior iliac spine in 63% of specimens. There was no radiographic evidence of spread to the thoracic paravertebral space. Anatomical dissection revealed dye staining of the upper branches of the lumbar plexus and the psoas major muscle in 70% of specimens. Further clinical studies are required to confirm if the quadratus lumborum block might be a suitable alternative to lumbar plexus block.

Concepts: Biology, Transversus abdominis muscle, Anatomy, Iliac crest, Lumbar plexus, Dissection, Iliohypogastric nerve, Psoas major muscle


Increasingly, patients with multiple co-morbidities undergo surgery for rectal cancer. We aimed to evaluate if decreased psoas muscle area and volume, as measures for sarcopenia, were associated with postoperative morbidity.

Concepts: Psoas major muscle


The clinical reliability and reproducibility of ultrasound-guided lumbar plexus blocks is not established in pediatric populations. We present the results of a combined nerve stimulation ultrasound-guided lumbar plexus block using the vertebral body, transverse process, and psoas muscle as landmarks on a transverse lumbar paravertebral sonogram with mid-axillary transducer placement, “shamrock method,” in children and adolescents.

Concepts: Scientific method, Vertebra, Neck, Process, Block, Lumbar plexus, Psoas major muscle, Iliacus muscle


Frailty has been associated with worse outcomes in older trauma patients. Specifically, the utility of lean cross-sectional psoas muscle area (LPA) was examined as a potentially simple objective measure of frailty.

Concepts: Physical trauma, Psoas major muscle, Psoas minor muscle


In experiments on active muscle, we examined the tension decline and its temperature sensitivity at the onset of ramp shortening and at a range of velocities. A segment (∼1.5 mm long) of a skinned muscle fibre isolated from rabbit psoas muscle was held isometric (sarcomere length ∼2.5µm) at 8-9 °C, maximally Ca-activated and a ramp shortening applied. The tension decline with a ramp shortening showed an early decrease of slope (the P1 transition) followed by a slower decrease in slope (the P2 transition) to the steady (isotonic) force. The tension level at the initial P1 transition and the time t1 to that transition decreased as the velocity is increased; the length change L1 to this transition increased with shortening velocity to a steady value of ∼8 nm / half-sarcomere. A small rapid temperature jump (3-4 °C, <0.2 ms, T-jump) applied coincident with the onset of ramp shortening showed force enhancement by T-jump and changed the tension decline markedly. Analyses showed that the rate of T-jump induced force rise increased linearly with increase of shortening velocity. The results provide crucial evidence that the strain-sensitive crossbridge force generation, or a step closely coupled to it, is endothermic.

Concepts: Thermodynamics, English-language films, Muscle contraction, Muscular system, Sarcomere, Derivative, Knitting, Psoas major muscle


Ultrasound-guided lumbar plexus blocks usually require confirmatory neurostimulation. A simpler alternative is to inject local anaesthetic inside the posteromedial quadrant of the psoas muscle under ultrasound guidance.

Concepts: Anesthesia, Local anesthetic, Block, Lumbar plexus, Psoas major muscle, Iliacus muscle