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an abnormal inward (forward) curvature of the vertebral column (同)hollow-back

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/03 17:34:36」(JST)

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The term lordosis refers to the normal inward lordotic curvature of the lumbar and cervical regions of the spine.^[1] Excessive curvature of the lower back is known as lumbar hyperlordosis, commonly called sway back, hollow back or saddle back (after a similar condition that affects some horses). A major feature of lumbar hyperlordosis is a forward pelvic tilt, resulting in the pelvis resting on top of the thighs. Curvature in the opposite convex direction, in the thoracic and sacral regions is termed kyphotic. When this curvature is excessive it is called kyphosis or hyperkyphosis.

Cause

Normal lordotic curvatures, also known as secondary curvatures results in a difference in the thickness between the front and back parts of the intervertebral disc. Lordosis may also increase at puberty sometimes not becoming evident until the early or mid-20s. Imbalances in muscle strength and length are also a cause, such as weak hamstrings, or tight hip flexors (psoas).^{[citation needed]}

Other health conditions and disorders can cause lordosis. Achondroplasia (a disorder where bones grow abnormally which can result in short stature as in dwarfism), Spondylolisthesis (a condition in which vertebrae slip forward) and osteoporosis (the most common bone disease in which bone density is lost resulting in bone weakness and increased likelihood of fracture) are some of the most common causes of lordosis. Other causes include obesity, kyphosis (spine curvature disorder in which the thoracic curvature is abnormally rounded), discitits (an inflammation of the intervertebral disc space caused by infection) and benign juvenile lordosis.^[2]

Excessive lordotic curvature – lumbar hyperlordosis, is also called hollow back, saddle back, and swayback,^{[by whom?]} although swayback can also refer to a nearly opposite postural misalignment that can initially look quite similar.^[3]^[4] Common causes of lumbar hyperlordosis include tight low back muscles, excessive visceral fat, and pregnancy. Rickets, a vitamin D deficiency in children, can cause lumbar lordosis.

Effects

Although lordosis gives an impression of a stronger back, incongruently it can lead to moderate to severe lower back pain.

Diagnosis

Measurement and diagnosis of lumbar lordosis can be difficult. Obliteration of vertebral end-plate landmarks by interbody fusion may make the traditional measurement of segmental lumbar lordosis more difficult. Because the L4-L5 and L5-S1 levels are most commonly involved in fusion procedures, or arthrodesis, and contribute to normal lumbar lordosis, it is helpful to identify a reproducible and accurate means of measuring segmental lordosis at these levels.^[5]^[6]

A visible sign of lordosis is an abnormally large arch of the lower back and the person appears to be puffing out his or her stomach and buttocks. Precise diagnosis of lordosis is done by looking at a complete medical history, physical examination and other tests of the patient. X-rays are used to measure the lumbar curvature, bone scans are conducted in order to rule out possible fractures and infections, magnetic resonance imaging (MRI) is used to eliminate the possibility of spinal cord or nerve abnormalities, and computed tomography scans (CT scans) are used to get a more detailed image of the bones, muscles and organs of the lumbar region.^[7]

Treatment

Lumbar lordosis may be treated by strengthening the hip extensors on the back of the thighs, and by stretching the hip flexors on the front of the thighs.

Only the muscles on the front and on the back of the thighs can rotate the pelvis forward or backward while in a standing position because they can discharge the force on the ground through the legs and feet. Abdominal muscles and erector spinae can't discharge force on an anchor point while standing, unless one is holding his hands somewhere, hence their function will be to flex or extend the torso, not the hip^{[citation needed]}. Back hyper-extensions on a Roman chair or inflatable ball will strengthen all the posterior chain and will treat lordosis. So too will stiff legged deadlifts and supine hip lifts and any other similar movement strengthening the posterior chain without involving the hip flexors in the front of the thighs. Abdominal exercises could be avoided altogether if they stimulate too much the psoas and the other hip flexors.

Controversy regarding the degree to which manipulative therapy can help a patient still exists. If therapeutic measures reduce symptoms, but not the measurable degree of lordotic curvature, this could be viewed as a successful outcome of treatment, though based solely on subjective data. The presence of measurable abnormality does not automatically equate with a level of reported symptoms.^[8]

While not really a 'treatment', the art of tai chi chuan calls for adjusting the lower back curvature (as well as the rest of the spinal curvatures) through specific re-alignments of the pelvis to the thighs, it's referred to in shorthand as 'dropping the tailbone'. The specifics of the structural change are school specific, and are part of the jibengung (body change methods) of these schools. The adjustment is referred to in tai chi chuan literature as 'when the lowest vertebrae are plumb erect...' ^[9]

Other animals

A horse with significant lordosis

Lordosis can be also seen in animals, in particular horses and other equines. Usually called "swayback," soft back, or low back, it is an undesirable conformation trait. Swayback is caused in part from a loss of muscle tone in both the back and abdominal muscles, plus a weakening and stretching of the ligaments. As in humans, it may be influenced by bearing young; it is sometimes seen in a broodmare that has had multiple foals. However, it is also common in older horses whose age leads to loss of muscle tone and stretched ligaments. It also occurs due to overuse or injury to the muscles and ligaments from excess work or loads, or from premature work placed upon an immature animal. Equines with too long a back are more prone to the condition than those with a short back, but as a longer back is also linked to smoother gaits, the trait is sometimes encouraged by selective breeding. It has been found to have a hereditary basis in the American Saddlebred breed, transmitted via a recessive mode of inheritance. Research into the genetics underlying the condition has several values beyond just the Saddlebred breed as it may "serve as a model for investigating congenital skeletal deformities in horses and other species."^[10]

Lordosis in a sexual context is the naturally occurring position for sexual receptivity in non-primate mammalian females. The lordosis position is facilitated by the appropriate sensory input, such as touch or smell. For example, in female hamsters, when they are in the correct hormonal state there are areas on the flank, that when touched by the male, facilitate lordosis. ^[11]

Several brain areas are known to be important for the regulation of lordosis, including the ventromedial nucleus of the hypothalamus (VMN). The activity of the VMN in the regulation of lordosis is estrogen-dependent and when it is lesioned lordosis is abolished. Displays of lordosis can be affected by exposure to stress during puberty.^[12] ^[13] Specifically, stress can suppressed the hypothalamic-pituitary-gonadal (HPG) axis and therefore decrease concentrations of gonadal hormones. Consequently, these reductions in exposure to gonadal hormones around puberty can result in decreases in sexual behavior in adulthood, including displays of lordosis.^[14]

Other

Lordosis behavior refers to the position that some mammalian females (including cats, mice, and rats) display when they are ready to mate ("in heat"). The term is also used to describe mounting behavior in male mammals.

In radiology, a lordotic view is an X-ray taken of a patient leaning backwards.^[15]

Lordosis in the human spine makes it easier for humans to bring the bulk of their mass over the pelvis. This allows for a much more efficient walking gait than that of other primates, whose inflexible spines cause them to resort to an inefficient forward leaning "bent-knee, bent-waist" gait. As such, lordosis in the human spine is considered one of the primary physiological adaptations of the human skeleton that allows for human gait to be as energetically efficient as it is.^[16]

Footnotes

^ Medical Systems: A Body Systems Approach, 2005
^ "Types of Spine Curvature Disorders". WebMD. Retrieved 8 December 2013.
^ "Sway back posture". lower-back-pain-management.com/. Retrieved 17 August 2014.
^ Cressey, Eric. "Strategies for Correcting Bad Posture – Part 4". EricCressey.com. Retrieved 17 August 2014.
^ Schuler Thomas C (Oct 2004). "Segmental Lumbar Lordosis: Manual Versus Computer-Assisted Measurement Using Seven Different Techniques". J Spinal Disord Tech. 17 (5): 372–9.
^ Subach Brian R (Oct 2004). "Segmental Lumbar Lordosis: Manual Versus Computer-Assisted Measurement Using Seven Different Techniques". J Spinal Disord Tech 17 (5): 372–9.
^ "Lordosis". Lucile Packard Children's Hospital. Missing or empty |url= (help); |accessdate= requires |url= (help)
^ Harrison DD et al. (1994). J Manipulative Physiol Ther 17 (7): 454–464. Missing or empty |title= (help)
^ T'ai Chi Ch'uan: A Simplified Method of Calisthenics for Health & Self Defence | By Manqing Zheng | Page 10
^ Oke, Stacey. "Genetics of Swayback in Saddlebred Horses Examined" The Horse online edition, December 20, 2010. Accessed December 21, 2010
^ Randy Joe Nelson (2011). An Introduction to Behavioral Endocrinology (4 ed.). pp. 319–321.
^ Jasmina Kercmar and Stuart Tobet and Gregor Majdic (2014). "Social Isolation during Puberty Affects Female Sexual Behavior in Mice". Frontiers 8: 337. doi:10.3389/fnbeh.2014.00337. PMID 25324747.
^ D. Daniels and LM. Flanagan-Cato (2000). "Social Isolation during Puberty Affects Female Sexual Behavior in Mice". J Neurobiology 45: 1–13. PMID 10992252.
^ Jasmina Kercmar and Stuart Tobet and Gregor Majdic (2014). "Social Isolation during Puberty Affects Female Sexual Behavior in Mice". Frontiers 8: 337. doi:10.3389/fnbeh.2014.00337. PMID 25324747.
^ http://www.wikiradiography.com/page/Lordotic+Chest+Technique
^ http://www.algoless.com/pdf/human_gait.pdf

References

Gabbey, Amber. "Lordosis". Healthline Networks Incorporated. Retrieved 10 December 2013.
Gylys, Barbara A. and Mary Ellen Wedding (2005), Medical Terminology Systems, F.A. Davis Company
"Osteoporosis-overview". A.D.A.M. Retrieved 8 December 2013.

External links

What is Lordosis?
Lordosis - MedlinePlus definition
Lordosis - SpineUniverse

UpToDate Contents

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1. 女性における慢性骨盤痛の評価 evaluation of chronic pelvic pain in women
2. 大葉性無気肺の放射線学的パターン radiologic patterns of lobar atelectasis
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English Journal

Lumbar lordosis.

Been E1, Kalichman L2.Author information 1Physical Therapy Department, Zefat Academic College, Safed, Israel; Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: beenella@post.tau.ac.il.2Department of Physical Therapy, Recanati School for Community Health Professions, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.AbstractLumbar lordosis is a key postural component that has interested both clinicians and researchers for many years. Despite its wide use in assessing postural abnormalities, there remain many unanswered questions regarding lumbar lordosis measurements. Therefore, in this article we reviewed different factors associated with the lordosis angle based on existing literature and determined normal values of lordosis. We reviewed more than 120 articles that measure and describe the different factors associated with the lumbar lordosis angle. Because of a variety of factors influencing the evaluation of lumbar lordosis such as how to position the patient and the number of vertebrae included in the calculation, we recommend establishing a uniform method of evaluating the lordosis angle. Based on our review, it seems that the optimal position for radiologic measurement of lordosis is standing with arms supported while shoulders are flexed at a 30° angle. There is evidence that many factors, such as age, gender, body mass index, ethnicity, and sport, may affect the lordosis angle, making it difficult to determine uniform normal values. Normal lordosis should be determined based on the specific characteristics of each individual; we therefore presented normal lordosis values for different groups/populations. There is also evidence that the lumbar lordosis angle is positively and significantly associated with spondylolysis and isthmic spondylolisthesis. However, no association has been found with other spinal degenerative features. Inconclusive evidence exists for association between lordosis and low back pain. Additional studies are needed to evaluate these associations. The optimal lordotic range remains unknown and may be related to a variety of individual factors such as weight, activity, muscular strength, and flexibility of the spine and lower extremities.
The spine journal : official journal of the North American Spine Society.Spine J.2014 Jan 1;14(1):87-97. doi: 10.1016/j.spinee.2013.07.464. Epub 2013 Oct 2.
Lumbar lordosis is a key postural component that has interested both clinicians and researchers for many years. Despite its wide use in assessing postural abnormalities, there remain many unanswered questions regarding lumbar lordosis measurements. Therefore, in this article we reviewed different fa
PMID 24095099

Numerical evaluation of the correlation between the normal variation in the sagittal alignment of the lumbar spine and the spinal loads.

Galbusera F, Brayda-Bruno M, Costa F, Wilke HJ.Author information IRCCS Istituto Ortopedico Galeazzi, Via Galeazzi 4, Milan, 20161, Italy.AbstractWe present a numerical approach to reproduce various patterns of spino-pelvic organization. We wanted to predict the spinal loads in two static conditions (standing and holding a weight in the hands) based on parameters describing the shape of the lumbar spine: type following Roussouly classification, sacral slope, apex, inflection point and lumbar lordosis. Four hundred eighty finite element models including trunk muscles and representing the entire range of normal variability were created. The models predicted that, in the case of a moderate external load of 50 N, a lordotic and well balanced spine (e.g., type 3) could reduce the muscle activation in comparison with a more lordotic (type 4) spine, with negligible differences compared to a more straight spine (type 2). However, such a sagittal configuration was not correlated with a minimization of the loading state in the intervertebral discs, especially regarding anteroposterior shear loads. In the standing posture without any additional load, a less lordotic and more vertical spine (e.g., types 1 and 2) was sufficient to ensure a condition of minimal spinal loads. Despite a number of limitations, inverse statics numerical models of spine biomechanics including trunk muscles appear to be a promising tool to fill the knowledge gap between the clinical observations of the correlations between the spino-pelvic organization and the consequent spinal disorders. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
Journal of orthopaedic research : official publication of the Orthopaedic Research Society.J Orthop Res.2013 Dec 27. doi: 10.1002/jor.22569. [Epub ahead of print]
We present a numerical approach to reproduce various patterns of spino-pelvic organization. We wanted to predict the spinal loads in two static conditions (standing and holding a weight in the hands) based on parameters describing the shape of the lumbar spine: type following Roussouly classificatio
PMID 24375659

Expansion Open-door Laminoplasty with Foraminotomy versus Anterior Cervical Discectomy and Fusion for Coexisting Multilevel Cervical Myelopathy and Unilateral Radiculopathy.

Fang Z, Tian R, Sun TW, Yadav SK, Hu W, Xie SQ.Author information *Department of Spine Surgery, Tianjin Union Medicine Center, Tianjin Institute of Spine Surgery †Nankai University, Tianjin, China.AbstractSTUDY DESIGN:: A clinical prospective study.
Journal of spinal disorders & techniques.J Spinal Disord Tech.2013 Dec 17. [Epub ahead of print]
STUDY DESIGN:: A clinical prospective study.OBJECTIVE:: To assess whether clinical and radiologic outcomes differ between expansion open-door laminoplasty with foraminotomy (EOLF) and anterior cervical discectomy and fusion (ACDF) in the treatment of coexisting multilevel cervical myelopathy and uni
PMID 24352034

Japanese Journal

Kinematics of Cervical Total Disc Replacement Adjacent to a Two-Level, Straight Versus Lordotic Fusion

MARTIN Shelden,GHANAYEM Alexander J.,TZERMIADIANOS Michael N.,VORONOV Leonard I.,HAVEY Robert M.,RENNER Susan M.,CARANDANG Gerard,ABJORNSON Celeste,PATWARDHAN Avinash G.
Spine 36(17), 1359-1366, 2011-08-01
NAID 10030716307

膝当てを取り付けた前傾座面椅子と従来の椅子間における座位時の体幹筋活動と脊椎カーブの比較　　‐２種類の座位姿勢からの検討‐:―2種類の座位姿勢からの検討―

鈴木哲,平田淳也,大槻桂右,渡邉進
理学療法科学 26(2), 263-267, 2011
〔目的〕膝当てを取り付けた前傾座面椅子と従来の椅子間で，脱力座位と直立座位の際の脊椎カーブと体幹筋活動を比較すること．〔対象〕健常な成人女性10名（25.7±4.9歳）とした．〔方法〕従来の椅子と前傾座面椅子上で，それぞれ脱力座位と直立座位を保持し，その際の体幹筋活動および脊椎カーブを測定した．〔結果〕前傾座面椅子上で脱力座位を保持した際の胸椎および腰椎カーブは，従来の椅子上と比べて，有意に前彎位 …
NAID 130004432745