Intervertebral Disc
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
The height of the discs in the coronal plane increases from the peripheral edges to the centre, appearing as a biconvex shape that becomes about 11% larger per segment from cephalad to caudal (from the cervical spine to the lumbosacral articulation). In the lumbar and cervical spine the discs are thicker in the anterior portion contributing to lordosis. L5/S1 is the thickest disc with L4/5 being the largest and most avascular disc. In the thoracic spine the discs are uniform in height, and are thicker caudally (possibly allowing greater movement). The thoracic spinal curvature is due to the shape of vertebral bodies.
History taking and clinical examination in musculoskeletal disease
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
Back. Check the skin at the base of the spine for hairy tufts and dimples (underlying spina bifida). Prominence of the spinal muscles on one side may be the result of muscle spasm secondary to pain. Side. The lumbar spine has a smooth concavity known as the lumbar lordosis (normal range is 40-60°). Muscle spasm is a cause of loss of the normal lordosis.
Cardiovascular Symptoms: Is It Pregnancy or the Heart?
Afshan B. Hameed, Diana S. Wolfe in Cardio-Obstetrics, 2020
Back pain generally begins around mid-pregnancy. Onset may vary and start earlier in the first trimester, typically peaking at 24–36 weeks of gestation [32]. Mild to moderate low back pain is very common due to spinal changes, i.e., physiologic lordosis, and may be considered normal. In contrast, midclavicular or upper back pain is not typical for normal pregnancy and may be indicative of a serious etiology such as pulmonary PE or aortic dissection. If the pain is reproducible and/or relieved on physical exam, it is more reflective of musculoskeletal condition. There are a few case series suggestive of an association between neuraxial anesthesia and interscapular back pain, but this is not well studied [33]. Differential diagnosis: Normal due to musculoskeletal changes in pregnancy, asthma, aortic dissection, PE.
Biomechanical analysis of segmental lumbar lordosis and risk of cage subsidence with different cage heights and alternative placements in transforaminal lumbar interbody fusion
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Sajjad Rastegar, Pierre-Jean Arnoux, Xiaoyu Wang, Carl-Éric Aubin
Cage subsidence in transforaminal lumbar interbody fusion (TLIF) is one of the concerns. The objective was to numerically assess the resulting segmental lumbar lordosis (SLL) and stresses at the bone-cage interface as functions of cage height (8- vs. 10-mm) and cage placement (oblique asymmetric, vs. anterior symmetric) for normal and osteoporotic bone quality. A L4-L5 detailed finite element model of TLIF was subjected to the functional loadings of 10 Nm in the physiological planes after the application of a 400 N follower-load. The SLL was increased by 0.9° (11%) and 1.0° (13%), respectively in oblique asymmetric and anterior symmetric cage placement with 8-mm height; they were 1.4° (18%) and 1.7° (21%) for the 10-mm cage. The maximum stresses at the cage-bone interface, in normal bone model, were increased up to 16% and 41% with the 10-mm cage and asymmetric oblique placement, respectively, and they increased up to 16% and 43% in osteoporotic bone model. The greater cage resulted to a higher simulated SLL. Oblique asymmetric placement and the use of a greater cage may increase the risk of cage subsidence. Due to the lower mechanical strength of osteoporotic bone, the risk of cage subsidence should be higher.
Biomechanical analysis of lumbar interbody fusion cages with various lordotic angles: a finite element study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
Zhenjun Zhang, Guy R. Fogel, Zhenhua Liao, Yitao Sun, Weiqiang Liu
Inappropriate lordotic angle of lumbar fusion cage could be associated with cage damage or subsidence. The biomechanical influence of cage lordotic angle on lumbar spine has not been fully investigated. Four surgical finite element models were constructed by inserting cages with various lordotic angles at L3-L4 disc space. The four motion modes were simulated. The range of motion (ROM) decreased with increased lordotic angle of cage in flexion, extension, and rotation, whereas it was not substantially changed in bending. The maximum stress in cage decreased with increased lordotic angle of cage in all motion modes. The maximum stress in endplate at surgical level increased with increased lordotic angle of cage in flexion and rotation, whereas it was not substantially changed in extension and bending. The facet joint force (FJF) was much smaller than that for the intact conditions in extension, bending, and rotation, while it was not substantially changed in flexion. In conclusion, the ROM, stresses in the cage and endplate at surgical level are sensitive to the lordotic angle of cage. The increased cage lordotic angle may provide better stability and reduce the risk of cage damage, whereas it may increase the risk of subsidence in flexion and rotation.
The reliability, minimal detectable change and concurrent validity of a gravity-based bubble inclinometer and iphone application for measuring standing lumbar lordosis
Published in Physiotherapy Theory and Practice, 2014
Purpose: To investigate the reliability, minimal detectable change (MDC90) and concurrent validity of a gravity-based bubble inclinometer (inclinometer) and iPhone® application for measuring standing lumbar lordosis. Methods: Two investigators used both an inclinometer and an iPhone® with an inclinometer application to measure lumbar lordosis of 30 asymptomatic participants. Results: ICC models 3,k and 2,k were used for the intrarater and interrater analysis, respectively. Good interrater and intrarater reliability was present for the inclinometer with Intraclass Correlation Coefficients (ICC) of 0.90 and 0.85, respectively and the iPhone® application with ICC values of 0.96 and 0.81. The minimal detectable change (MDC90) indicates that a change greater than or equal to 7° and 6° is needed to exceed the threshold of error using the iPhone® and inclinometer, respectively. The concurrent validity between the two instruments was good with a Pearson product-moment coefficient of correlation (r) of 0.86 for both raters. Ninety-five percent limits of agreement identified differences ranging from 9° greater in regards to the iPhone® to 8° less regarding the inclinometer. Conclusion: Both the inclinometer and iPhone® application possess good interrater reliability, intrarater reliability and concurrent validity for measuring standing lumbar lordosis. This investigation provides preliminary evidence to suggest that smart phone applications may offer clinical utility comparable to inclinometry for quantifying standing lumbar lordosis. Clinicians should recognize potential individual differences when using these devices interchangeably.