Heritability of Thoracic Spine Curvature and Genetic Correlations With Other Spine Traits: The Framingham Study

Osteoporosis, spinal degenerative disorders, and their association with low back pain, activities of daily living, and physical performance in a general population

Osteoporosis, vertebral fractures, and spinal degenerative diseases are common conditions that often coexist in older adults. This study aimed to determine the factors influencing low back pain and its impact on activities of daily living (ADL) and physical performance in older individuals with multiple comorbidities. This cross-sectional study was part of a large-scale population-based cohort study in Japan, involving 1009 participants who underwent spinal magnetic resonance imaging (MRI) to assess cervical cord compression, radiographic lumbar spinal stenosis, and lumbar disc degeneration. Vertebral fractures in the thoracolumbar spine were evaluated using sagittal MRI with a semi-quantitative method. Bone mineral density was measured using dual-energy X-ray absorptiometry. Low back pain, Oswestry Disability Index (ODI), and physical performance tests, such as one-leg standing time, five times chair-stand time, maximum walking speed, and maximum step length, were assessed. Using clinical conditions as objective variables and image evaluation parameters as explanatory variables, multiple regression analysis showed that vertebral fractures were significantly associated with low back pain and ODI. Vertebral fractures and osteoporosis significantly impacted physical performance, whereas osteoporosis alone did not affect low back pain or ODI. Our findings contribute to new insights into low back pain and its impact on ADL and physical performance.

Relationship among Osteoporosis, Sarcopenia, Locomotive Syndrome, and Spinal Kyphosis in Older Individuals Living in a Local Mountain Area

STUDY DESIGN

Cross-sectional cohort study.

PURPOSE

This study investigated the relationship among osteoporosis, sarcopenia, locomotive syndrome, and spinal kyphosis in older individuals living in a mountain area.

OVERVIEW OF LITERATURE

Kyphosis greatly reduces the quality of life of older individuals. Osteoporosis and sarcopenia are kyphosiscausing factors.

METHODS

This cross-sectional study included 361 individuals aged ≥65 years (mean age, 75.0 years) living in a local mountain area and underwent medical check-ups from 2014 to 2018. The survey items included kyphosis index, body mass index, back pain prevalence, back pain Visual Analog Scale score, Oswestry Disability Index, walking speed, grip strength, skeletal mass index, osteoporosis (% young adult mean [YAM]), LOCOMO 5 score, and presence of sarcopenia (Asian Working Group for Sarcopenia). The participants were divided into the N (kyphosis index: <12; n=229, 63.4%), M (kyphosis index: 12-15; n=99, 27.4%), and K (kyphosis index: ≥15; n=33, 9.2%) groups. p -values of <0.05 were considered statistically significant. An association factor of kyphosis (kyphosis index: ≥15) was investigated with logistic regression analysis.

RESULTS

Age and LOCOMO 5 scores were significantly higher (p <0.05) and %YAM and walking speed were significantly lower (p <0.05) in the K group than in the M and N groups. Other survey items showed significant differences. Only %YAM (odds ratio, 0.20; 95% confidence interval, 0.04-0.96) was an independent factor associated with a kyphosis index of ≥15.

CONCLUSIONS

Decreased muscle mass and muscle strength would be related to kyphosis; however, no such relations were noted. Bone loss was significantly related to kyphosis. Osteoporosis-induced decrease in vertebral body height is present in the background. Sarcopenia and locomotive syndrome were not related to kyphosis, whereas decreased bone density was independently associated with kyphosis in older individuals living in a mountain area.

Polg mtDNA mutator mice reveal limited involvement of vertebral bone loss in premature aging-related thoracolumbar hyperkyphosis

Background

Age-related hyperkyphosis is multifactorial and involves alterations of vertebral bone, intervertebral discs (IVD) and paraspinal muscles. The relative contribution of these tissues remains unclear. Here, we compared differences in vertebral bone microarchitecture and IVD thickness between prematurely aging mice with spinal hyperkyphosis and wild type littermates.

Methods

Thoracolumbar vertebral columns were dissected from homozygous Polg ^D257A and age-matched wild type littermates. Micro-computed tomography was performed to quantify cortical and trabecular bone parameters at anterior and posterior portions of T8-L4 vertebrae. In addition, vertebral shape, transaxial facet joint orientation and IVD thickness were quantified. Differences in anterior/posterior ratios between genotypes were compared by Student's t-test and association between vertebral bone and IVD parameters was investigated using Pearson correlation analysis.

Results

Hyperkyphotic homozygous mice displayed generalized osteopenia that was more pronounced at the posterior compared with anterior portion of thoracolumbar vertebrae. An increase in the anterior/posterior ratio of trabecular bone parameters was revealed at the thoracolumbar junction (T13-L1). Polg ^D257A displayed diffuse loss of cortical bone thickness, yet anterior/posterior ratios were unchanged. Despite generalized and regional bone loss, vertebral shape was unaffected. PolG ^D257A mice showed a 10-20 % reduction of IVD thickness at both thoracic and lumbar levels, with only minimal histopathological changes. IVD thickness was negatively correlated with anterior/posterior ratios of trabecular bone parameters, as well as with more coronally oriented facet joints, but negatively correlated with the anterior/posterior ratio of cortical bone thickness.

Conclusions

Aging-induced regional changes of vertebral trabecular and cortical bone did not lead to altered vertebral shape in Polg ^D257A mice but may indirectly cause hyperkyphosis through reduction of IVD thickness. These findings suggest a limited role for aging-induced bone loss in spinal hyperkyphosis and warrants further research on the involvement of paraspinal muscle degeneration.

A protocol for recruiting and analyzing the disease-oriented Russian disc degeneration study (RuDDS) biobank for functional omics studies of lumbar disc degeneration

Lumbar intervertebral disc degeneration (DD) disease is one of the main risk factors for low back pain and a leading cause of population absenteeism and disability worldwide. Despite a variety of biological studies, lumbar DD is not yet fully understood, partially because there are only few studies that use systematic and integrative approaches. This urges the need for studies that integrate different omics (including genomics and transcriptomics) measured on samples within a single cohort. This protocol describes a disease-oriented Russian disc degeneration study (RuDDS) biobank recruitment and analyses aimed to facilitate further omics studies of lumbar DD integrating genomic, transcriptomic and glycomic data. A total of 1,100 participants aged over 18 with available lumbar MRI scans, medical histories and biological material (whole blood, plasma and intervertebral disc tissue samples from surgically treated patients) will be enrolled during the three-year period from two Russian clinical centers. Whole blood, plasma and disc tissue specimens will be used for genotyping with genome-wide SNP-arrays, glycome profiling and RNA sequencing, respectively. Omics data will be further used for a genome-wide association study of lumbar DD with in silico functional annotation, analysis of plasma glycome and lumbar DD disease interactions and transcriptomic data analysis including an investigation of differential expression patterns associated with lumbar DD disease. Statistical tests applied in each of the analyses will meet the standard criteria specific to the attributed study field. In a long term, the results of the study will expand fundamental knowledge about lumbar DD development and contribute to the elaboration of novel personalized approaches for disease prediction and therapy. Additionally to the lumbar disc degeneration study, a RuDDS cohort could be used for other genetic studies, as it will have unique omics data.

Trial registration numberNCT04600544.

Lower thoracic spine extension mobility is associated with higher intensity of thoracic spine pain

Objectives

To evaluate the association of thoracic spine (TS) posture and mobility with TS pain.

Methods

Participants with TS pain reported maximum, average, and night pain in TS area, and pain summary score was calculated. Upright and sitting TS postures were evaluated by inspection. TS posture and mobility (flexion and extension) were recorded using an inclinometer and a tape measure, respectively. Correlations between posture and mobility assessments were calculated using Spearman rank correlation, the association of TS posture and mobility with TS pain by logistic regression analysis.

Results

The participants’ (n = 73, 52 females, age range 22–56) TS pain duration was 12 weeks on average. The correlations for measurements of TS posture and flexion mobility were higher than correlations of other TS measurements being between 0.53 and 0.82. Decreased extension mobility of the upper (from 1^st to 6^th TS segments; Th1–Th6) TS was associated with higher worst pain (OR 1.04, 95% CI 1.00–1.07) and whole TS with pain sum score (OR 1.05, 95% CI 1.01–1.08). Less kyphotic whole TS was associated with lower pain sum score (OR 0.96, 95% CI 0.92–1.00). Greater flexion mobility of upper and lower (Th6–Th12) TS were associated with lower pain sum score (OR 0.96, 95% CI 0.91–1.00, and OR 0.96, 95% CI 0.91–1.00, respectively).

Conclusions

Reduced thoracic extension mobility was associated with higher pain scores and the greater flexion mobility with lower pain scores. Future research is warranted to evaluate if treatments geared toward TS extension mobility improvements would result in lower TS pain.

Decreasing thoracic hyperkyphosis - Which treatments are most effective? A systematic literature review and meta-analysis

BACKGROUND

A variety of treatments aim to reduce thoracic hyperkyphosis in adults, thereby improving posture and reducing possible complications.

OBJECTIVE

To investigate the effectiveness of treatments to reduce thoracic hyperkyphosis.

DESIGN

Systematic review and meta-analysis.

METHODS

MEDLINE, EMBASE, CINAHL, and CENTRAL were searched from inception to March 2021. Two authors independently selected randomised controlled trials assessing the effectiveness of treatments to reduce thoracic hyperkyphosis in adults. Raw data on mean change in thoracic kyphosis were extracted and standardised mean differences (SMD) calculated. Meta-analysis was performed on studies homogenous for study population and intervention. Strength of evidence was assessed using GRADE.

RESULTS

Twenty-eight studies were included, with five meta-analyses performed. Low to moderate-quality evidence found structured exercise programs of three-months duration or less effective in reducing thoracic hyperkyphosis in younger (SMD -2.8; 95%CI -4.3 to -1.3) and older populations (SMD -0.3; 95%CI -0.6 to 0.0). Low-quality evidence found bracing for three months or more effective in older participants (SMD -1.0, 95%CI -1.3 to -0.7). A single study demonstrated the effectiveness of multimodal care in younger participants. The available evidence suggests multimodal care, structured exercise programs over three months duration, and taping in older adults, and biofeedback and muscle stimulation in younger adults, are ineffective in reducing thoracic hyperkyphosis.

CONCLUSION

Low to moderate-quality evidence indicates that structured exercise programs are effective to reduce thoracic hyperkyphosis. Low-quality evidence indicates that bracing is effective to reduce thoracic hyperkphosis in older adults.

Factors Associated With Kyphosis and Kyphosis Progression in Older Men: The MrOS Study

Hyperkyphosis (HK), or increased anterior curvature of the thoracic spine, is common in older persons. Although it is thought that vertebral fractures are the major cause of HK, only about a third of those with the worst degrees of kyphosis have underlying vertebral fractures. In older men, HK is associated with increased risk of poor physical function, injurious falls, and earlier mortality, but its causes are not well understood. We studied 1092 men from the Osteoporotic Fractures in Men (MrOS) Study aged 64 to 92 years (mean age 72.8 years) who had repeated standardized radiographic measures of Cobb angle of kyphosis to identify risk factors for HK (defined as ≥50 degrees) and kyphosis progression over an interval of 4.7 years. Specifically, we examined the associations with age, body mass index (BMI), weight, weight loss, health behaviors, family history of HK, muscle strength, degenerative disc disease (DDD), bone mineral density (BMD), prevalent thoracic vertebral fractures, and incident thoracic vertebral fractures (longitudinal analyses only). Men had an average baseline kyphosis of 38.9 (standard deviation [SD] 11.4) degrees. Fifteen percent had HK (n = 161) with a mean Cobb angle of 56.7 (SD = 6.0) degrees; these men were older (p < 0.01), had lower BMI (p < 0.01), lower BMD (p < 0.01), were more likely to have family history of HK (p = 0.01), and prevalent thoracic vertebral fracture (p < 0.01) compared with the men without HK. During follow-up, men experienced an average of 1.4 degrees of kyphosis progression with DDD (p = 0.04) and lower hip BMD (p < 0.01) being identified as statistically significant and incident vertebral fractures (p = 0.05) nearly significant factors associated with worse progression. These results suggest that in older men, HK results from not only low BMD and vertebral fractures but that DDD also may play a significant role in kyphosis progression. © 2020 American Society for Bone and Mineral Research (ASBMR).

Validity of flexicurve and motion capture for measurements of thoracic kyphosis vs standing radiographic measurements

Thoracic kyphosis varies among healthy adults and typically increases with age. Excessive kyphosis (hyperkyphosis) is associated with negative health. Spinal alignment also affects spine loading, with implications for conditions such as vertebral fractures and back pain. Valid measurements of kyphosis are necessary for clinical and research assessment of age-related posture changes, and to support improved biomechanical understating of spine conditions. Independent validation of non-radiographic techniques, however, remains limited. The goal of this study was to compare standing radiographic kyphosis measurements with non-radiographic measurements and predictions of thoracic kyphosis using flexicurve and motion analysis markers, in order to determine their validity. Thirteen non-radiographic measures of thoracic kyphosis were obtained in each of 40 adult subjects who also underwent standing radiographs of the thoracic spine. Measures included estimates derived by fitting of polynomials or circles to the non-radiographic data, as well as predictions calculated using previously published methods. Intra-class correlations (ICC) and root-mean square errors (RMSEs) were calculated between radiographic and non-radiographic measures to determine validity. Most non-radiographic estimates of kyphosis show similar, weak to moderate levels of validity when compared to radiographic measurements, and RMSEs ranging from 8.0° to 20.8°. Unbiased estimates of radiographic measurements with moderate to good ICCs were identified, however, based on marker measurements, and new prediction equations were created with similar validity that also account for age and body habitus. Clinical significance: These non-radiographic measurements of thoracic kyphosis can be applied to clinical practice or to clinical studies with recognition of specific limitations.

Mobile Applications for Assessing Human Posture: A Systematic Literature Review

Smartphones are increasingly incorporated with features such as sensors and high resolution cameras that empower their capabilities, enabling their use for varied activities including human posture assessments. Previous reviews have discussed methods used in postural assessment but none of them focused exclusively on mobile applications. This paper systematically reviews mobile applications proposed for analyzing human posture based on alignment of the body in the sagittal and coronal plane. The main digital libraries were searched, 26 articles published between 2010 and 2020 were selected, and 13 mobile applications were identified, classified and discussed. Results showed that the use of mobile applications to assist with posture assessment have been demonstrated to be reliable, and this can contribute to clinical practice of health professionals, especially the assessment and reassessment phases of treatments, despite some variations when compared to traditional methods. Moreover, in the case of image-based applications, we highlight the advantage that measurements can be taken with the assessor at a certain distance with respect to the patient’s position, which is an important function for assessments performed in pandemic times such as the outbreak of COVID-19.

Effects of Long-Duration Spaceflight on Vertebral Strength and Risk of Spine Fracture

Although the negative impact of long-duration spaceflight on spine BMD has been reported, its impact on vertebral strength and risk of vertebral fracture remains unknown. This study examined 17 crewmembers with long-duration service on the International Space Station in whom computed tomography (CT) scans of the lumbar spine (L₁ and L₂ ) were collected preflight, immediately postflight and 1 to 4 years after return to Earth. We assessed vertebral strength via CT-based finite element analysis (CT-FEA) and spinal loading during different activities via subject-specific musculoskeletal models. Six months of spaceflight reduced vertebral strength by 6.1% (-2.3%, -8.7%) (median [interquartile range]) compared to preflight (p < 0.05), with 65% of subjects experiencing deficits of greater than 5%, and strengths were not recovered up to 4 years after the mission. This decline in vertebral strength exceeded (p < 0.05) the 2.2% (-1.3%, -6.0%) decline in lumbar spine DXA-BMD. Further, the subject-specific changes in vertebral strength were not correlated with the changes in DXA-BMD. Although spinal loading increased slightly postflight, the ratio of vertebral compressive load to vertebral strength for typical daily activities remained well below a value of 1.0, indicating a low risk of vertebral fracture despite the loss in vertebral strength. However, for more strenuous activity, the postflight load-to-strength ratios ranged from 0.3 to 0.7, indicating a moderate risk of vertebral fracture in some individuals. Our findings suggest persistent deficits in vertebral strength following long-duration spaceflight, and although risk of vertebral fracture remains low for typical activities, the risk of vertebral fracture is notable in some crewmembers for strenuous exercise requiring maximal effort. © 2019 American Society for Bone and Mineral Research.

The Clinical Relevance of Hyperkyphosis: A Narrative Review

The kyphosis angle of the thoracic spine tends to increase with aging. Hyperkyphosis is a kyphosis angle, exceeding the normal range. This narrative literature review aims to provide an overview of the current literature concerning kyphosis measurement methods, the etiology and adverse health effects of hyperkyphosis. As of yet, a well-defined threshold for hyperkyphosis is lacking. To attain more generalizability and to be able to compare study results in older adults, we propose to define age-related hyperkyphosis as a Cobb angle of 50° or more in standing position. Hyperkyphosis may be a potentially modifiable risk factor for adverse health outcomes, like fall risk and fractures. Additionally, hyperkyphosis may indicate the presence of osteoporosis, which is treatable. Prospective and intervention studies, using a Cobb angle of 50° as a clear and uniform definition of hyperkyphosis, are warranted to investigate the clinical relevance of hyperkyphosis.

A Longitudinal Study of Trunk Muscle Properties and Severity of Thoracic Kyphosis in Women and Men: The Framingham Study

BACKGROUND

Cross-sectional studies suggest that trunk muscle morphology in the lumbar spine is an important determinant of kyphosis severity in older adults. The contribution of age-related changes in muscle morphology in the thoracic and lumbar spine to progression of kyphosis is not known. Our objective was to determine cross-sectional and longitudinal associations of thoracic and lumbar muscle size and density with kyphosis.

METHODS

Participants were 1,087 women and men (mean age: 61 years) of the Framingham Heart Study who underwent baseline and follow-up quantitative computed tomography (QCT) scanning 6 years apart. We used QCT scans to measure trunk muscle cross-sectional area (CSA, cm2) and density (HU) at the thoracic and lumbar spine and Cobb angle (degrees) from T4 to T12. Linear regression models estimated the association between muscle morphology and kyphosis.

RESULTS

At baseline, smaller muscle CSA and lower density of thoracic (but not lumbar) spine muscles were associated with a larger (worse) Cobb angle in women and men. For example, each standard deviation decrease in baseline thoracic paraspinal muscle CSA was associated with a larger baseline Cobb angle in women (3.7 degrees, 95% CI: 2.9, 4.5) and men (2.5 degrees, 95% CI: 1.6, 3.3). Longitudinal analyses showed that loss of muscle CSA and density at the thoracic and lumbar spine was not associated with progression of kyphosis.

CONCLUSIONS

Our findings suggest that kyphosis severity is related to smaller and lower density trunk muscles at the thoracic spine. Future studies are needed to determine how strengthening mid-back musculature alters muscle properties and contributes to preventing kyphosis progression.

Prediction of incident vertebral fracture using CT-based finite element analysis

Prior studies show vertebral strength from computed tomography-based finite element analysis may be associated with vertebral fracture risk. We found vertebral strength had a strong association with new vertebral fractures, suggesting that vertebral strength measures identify those at risk for vertebral fracture and may be a useful clinical tool.

INTRODUCTION

We aimed to determine the association between vertebral strength by quantitative computed tomography (CT)-based finite element analysis (FEA) and incident vertebral fracture (VF). In addition, we examined sensitivity and specificity of previously proposed diagnostic thresholds for fragile bone strength and low BMD in predicting VF.

METHODS

In a case-control study, 26 incident VF cases (13 men, 13 women) and 62 age- and sex-matched controls aged 50 to 85 years were selected from the Framingham multi-detector computed tomography cohort. Vertebral compressive strength, integral vBMD, trabecular vBMD, CT-based BMC, and CT-based aBMD were measured from CT scans of the lumbar spine.

RESULTS

Lower vertebral strength at baseline was associated with an increased risk of new or worsening VF after adjusting for age, BMI, and prevalent VF status (odds ratio (OR) = 5.2 per 1 SD decrease, 95% CI 1.3-19.8). Area under receiver operating characteristic (ROC) curve comparisons revealed that vertebral strength better predicted incident VF than CT-based aBMD (AUC = 0.804 vs. 0.715, p = 0.05) but was not better than integral vBMD (AUC = 0.815) or CT-based BMC (AUC = 0.794). Additionally, proposed fragile bone strength thresholds trended toward better sensitivity for identifying VF than that of aBMD-classified osteoporosis (0.46 vs. 0.23, p = 0.09).

CONCLUSION

This study shows an association between vertebral strength measures and incident vertebral fracture in men and women. Though limited by a small sample size, our findings also suggest that bone strength estimates by CT-based FEA provide equivalent or better ability to predict incident vertebral fracture compared to CT-based aBMD. Our study confirms that CT-based estimates of vertebral strength from FEA are useful for identifying patients who are at high risk for vertebral fracture.

Correspondence between bone mineral density and intervertebral disc degeneration across age and sex

The distribution of bone tissue within the vertebra can modulate vertebral strength independently of average density and may change with age and disc degeneration. Our results show that the age-associated decrease in bone density is spatially non-uniform and associated with disc health, suggesting a mechanistic interplay between disc and vertebra.

PURPOSE

While the decline of bone mineral density (BMD) in the aging spine is well established, the extent to which age influences BMD distribution within the vertebra is less clear. Measures of regional BMD (rBMD) may improve predictions of vertebral strength and suggest how vertebrae might adapt with intervertebral disc degeneration. Thus, we aimed to assess how rBMD values were associated with age, sex, and disc height loss (DHL).

METHODS

We measured rBMD in the L3 vertebra of 377 participants from the Framingham Heart Study (41-83 years, 181 M/196 F). Integral (Int.BMD) and trabecular BMD (Tb.BMD) were measured from QCT images. rBMD ratios (anterior/posterior, superior/mid-transverse, inferior/mid-transverse, and central/outer) were calculated from the centrum. A radiologist assigned a DHL severity score to adjacent intervertebral discs (L2-L3 and L3-L4).

RESULTS

Int.BMD and Tb.BMD were both associated with age, though the decrease across age was greater in women (Int.BMD, - 2.6 mg/cm3 per year; Tb.BMD, - 2.6 mg/cm3 per year) than men (Int.BMD, - 0.5 mg/cm3 per year; Tb.BMD, - 1.2 mg/cm3 per year). The central/outer (- 0.027/decade) and superior/mid-transverse (- 0.018/decade) rBMD ratios were negatively associated with age, with similar trends in men and women. Higher Int.BMD or Tb.BMD was associated with increased odds of DHL after adjusting for age and sex. Low central/outer ratio and high anterior/poster and superior/mid-transverse ratios were also associated with increased odds of DHL.

CONCLUSIONS

Our results indicate that the distribution of bone within the L3 vertebra is different across age, but not between sexes, and is associated with disc degeneration.

A longitudinal study of disc height narrowing and facet joint osteoarthritis at the thoracic and lumbar spine, evaluated by computed tomography: the Framingham Study

BACKGROUND CONTEXT

Prevalence and progression of disc height narrowing (DHN) and facet joint osteoarthritis (FJOA) in the thoracic and lumbar regions in non-clinical populations are not well established.

PURPOSE

The present study aimed to use computed tomography (CT) images to determine the prevalence and progression of DHN and FJOA according to age, sex, and spinal region.

STUDY DESIGN

This is a 6-year longitudinal study.

SAMPLE

A total of 1,195 members of the Framingham Study (mean baseline age 61±9 years) were included in the study.

OUTCOME MEASURES

We compared the prevalence and progression (new or worsening) of moderate-to-severe DHN and FJOA by age, sex, and spinal region.

METHODS

A musculoskeletal radiologist evaluated DHN and FJOA from T4/T5 to L4/L5 on baseline and follow-up CT images using a semi-quantitative scale: 0=normal, 1=mild, 2=moderate, and 3=severe.

RESULTS

One-third or more of women and men ages 40-59 years at baseline had imaged-based evidence of prevalent DHN, more than half had prevalent FJOA, and DHN and FJOA prevalence increased approximately two- to fourfold in those age 60-69 and 70-89 years at baseline, respectively (p<.01). Progression of DHN and FJOA occurred more frequently at the lumbar than at the thoracic spine and more in women than in men (DHN: odds ratio [OR]=1.42, 95% confidence interval [CI]=1.07, 1.88; FJOA: OR=1.70, CI=1.33, 2.17).

CONCLUSIONS

Prevalence and progression of moderate-to-severe DHN and FJOA are common in non-clinical populations of older adults. The high frequency of spinal degeneration observed on CTs in this community-based study may contribute to challenges in interpreting the clinical significance of imaging evidence of DHN and FJOA. Future studies investigating the association of CT-based spinal degenerative features with pain and functional impairments in population-based samples are needed to help determine the clinical significance of imaged-based findings of DHN and FJOA.

Maternal Diets Deficient in Vitamin D Increase the Risk of Kyphosis in Offspring: A Novel Kyphotic Porcine Model

BACKGROUND

The purpose of this study was to explore the role of perinatal vitamin-D intake on the development and characterization of hyperkyphosis in a porcine model.

METHODS

The spines of 16 pigs were assessed at 9, 13, and 17 weeks of age with radiography and at 17 weeks with computed tomography (CT), magnetic resonance imaging (MRI), histology, and bone-density testing. An additional 169 pigs exposed to 1 of 3 maternal dietary vitamin-D levels from conception through the entire lactation period were fed 1 of 4 nursery diets supplying different levels of vitamin D, calcium, and phosphorus. When the animals were 13 weeks of age, upright lateral spinal radiography was performed with use of a custom porcine lift and sagittal Cobb angles were measured in triplicate to determine the degree of kyphosis in each pig.

RESULTS

The experimental animals had significantly greater kyphotic sagittal Cobb angles at all time points when compared with the control animals. These hyperkyphotic deformities demonstrated no significant differences in Hounsfield units, contained a slightly lower ash content (46.7% ± 1.1% compared with 50.9% ± 1.6%; p < 0.001), and demonstrated more physeal irregularities. Linear mixed model analysis of the measured kyphosis demonstrated that maternal diet had a greater effect on sagittal Cobb angle than did nursery diet and that postnatal supplementation did not completely eliminate the risk of hyperkyphosis.

CONCLUSIONS

Maternal diets deficient in vitamin D increased the development of hyperkyphosis in offspring in this model.

CLINICAL RELEVANCE

This study demonstrates that decreased maternal dietary vitamin-D intake during pregnancy increases the risk of spinal deformity in offspring. In addition, these data show the feasibility of generating a large-animal spinal-deformity model through dietary manipulation alone.

Patterns of menopausal hormone therapy use and hyperkyphosis in older women

OBJECTIVE

Hyperkyphosis, an exaggerated anterior curvature of the thoracic spine, is associated with poor physical function, falls, fractures, and earlier mortality. Low bone mineral density, bone loss, and vertebral fractures are strong risk factors for hyperkyphosis. Menopausal hormone therapy (HT) reverses bone loss, prevents vertebral fractures, and, therefore, we hypothesize, may reduce the risk for developing hyperkyphosis.

METHODS

We evaluated the cross-sectional association between Cobb angle of kyphosis from lateral spine radiographs and pattern of self-reported HT use during the prior 15-year period in 1,063 women from the Study of Osteoporotic Fractures.

RESULTS

Participants had a mean age of 83.7 ± 3.3 years and a mean Cobb angle of 51.3 ± 14.6°. Forty-six per cent of women were characterized as never-users of HT, 24% as remote past users, 17% as intermittent users, and 12% as continuous users. In minimally adjusted models, the mean Cobb angle was 4.0° less in continuous HT users compared with never-users (P = 0.01); however, in fully adjusted models, this association was attenuated to 2.8° (P = 0.06). Remote past HT users had 3.0° less kyphosis compared with never-users in minimally adjusted models (P = 0.01), attenuated to 2.8° less in fully adjusted models (P = 0.02). Intermittent users did not differ from never-users in degree of kyphosis.

CONCLUSIONS

Women reporting continuous or remote past HT use had less pronounced kyphosis than never-users by their mid-eighties, suggesting a possible role for HT in the prevention of age-related hyperkyphosis.

Evaluation of the influence of kyphosis and scoliosis on intervertebral disc extrusion in French bulldogs

BACKGROUND

Although thoracic vertebral malformations with kyphosis and scoliosis are often considered incidental findings on diagnostic imaging studies of screw-tailed brachycephalic breeds, they have been suggested to interfere with spinal biomechanics and intervertebral disc degeneration. It is however unknown if an abnormal spinal curvature also predisposes dogs to develop clinically relevant intervertebral disc herniations. The aim of this study was to evaluate if the occurrence of thoracic vertebral malformations, kyphosis or scoliosis would be associated with a higher prevalence of cervical or thoracolumbar intervertebral disc extrusion in French bulldogs.

RESULTS

French bulldogs that underwent computed tomography for reasons unrelated to spinal disease (n = 101), and French bulldogs with thoracolumbar (n = 47) or cervical intervertebral disc extrusion (n = 30) that underwent magnetic resonance imaging were included. There was a significant association between the presence of kyphosis and the occurrence of intervertebral disc extrusion, particularly in the thoracolumbar region. Dogs with kyphosis were at nearly a two times increased odds of being affected by intervertebral disc extrusion than those without kyphosis [(OR = 1.98 (95% CI: 1.04-3.78)]. There was also an association between the presence of scoliosis and the anatomical distribution of intervertebral disc extrusions, with dogs with scoliosis more likely to have more caudal lumbar intervertebral disc extrusions. Presence of scoliosis was not associated with an increased odds of being affected by intervertebral disc extrusion.

CONCLUSIONS

Although thoracic vertebral malformations with kyphosis only rarely cause spinal cord dysfunction in itself, French bulldogs with kyphosis appear to be at higher risk to develop thoracolumbar intervertebral disc extrusion.

Comparison of spinal alignment, muscular strength, and quality of life between women with postmenopausal osteoporosis and healthy volunteers

This study compared spinal alignment, muscular strength, and quality of life (QOL) between women with postmenopausal osteoporosis and healthy volunteers. The results indicated that lower QOL in osteoporosis patients may be associated with increased thoracic kyphosis, reduced lean muscle mass, and generalized muscle weakness.

INTRODUCTION

Increased spinal kyphosis is common in patients with osteoporosis and negatively impacts quality of life (QOL). Muscular strength is also important for QOL in patients with osteoporosis. However, spinal kyphosis and muscle weakness also occur in healthy individuals with advancing age. The purposes of this study were thus to compare spinal alignment, muscular strength, and QOL between women with postmenopausal osteoporosis and healthy volunteers.

METHODS

Participants comprised 236 female patients with postmenopausal osteoporosis (mean age, 68.7 years) and 93 healthy volunteer women (mean age, 71.0 years). Body mass index (BMI), angles of spinal kyphosis, back extensor strength, grip strength, and QOL were compared between groups.

RESULTS

BMI, back extensor strength, and grip strength were significantly higher in the volunteer group than in the osteoporosis group (p < 0.01). Both thoracic kyphosis and lumbar lordosis were significantly greater in the osteoporosis group than in the volunteer group (p < 0.01). With regard to QOL, the 36-Item Short-Form Health Survey (SF-36) subscale scores of role physical, bodily pain, general health, and role emotional were all significantly lower in the osteoporosis group than in the volunteer group (p < 0.05 each). SF-36 physical component summary (PCS) score was significantly lower in the osteoporosis group than in the volunteer group (p < 0.001). SF-36 PCS score correlated positively with thoracic kyphosis and negatively with BMI only in the osteoporosis group (p < 0.05 each).

CONCLUSIONS

These results indicated that lower QOL in osteoporosis patients may be associated with increased thoracic kyphosis, reduced lean muscle mass, and generalized muscle weakness.

Thoracic Kyphosis and Physical Function: The Framingham Study

OBJECTIVE

To evaluate the association between thoracic kyphosis and physical function.

DESIGN

Prospective cohort.

SETTING

Framingham, Massachusetts.

PARTICIPANTS

Framingham Heart Study Offspring and Third Generation cohort members who had computed tomography (CT) performed between 2002 and 2005 and physical function assessed a mean 3.4 years later (N = 1,100; mean age 61 ± 8, range 50-85).

MEASUREMENTS

Thoracic kyphosis (Cobb angle, T4-T12) was measured in degrees using supine CT scout images. Participants were categorized according to Cobb angle to compare those in the highest quartile (Q4, most-severe kyphosis) with those in the lowest quartiles (Q1-Q3). Quick walking speed (m/s), chair-stand time (seconds), grip strength (kg), and self-reported impairments were assessed using standardized procedures. Analyses were adjusted for age, height, weight, smoking, follow-up time, vertebral fractures, and prevalent spinal degeneration.

RESULTS

Thoracic kyphosis was not associated with physical function in women or men, and these results were consistent in those younger than 65 and those aged 65 and older. For example, walking speed was similar in adults younger than 65 with and without severe kyphosis (women, Q4: 1.38 m/s, Q1-Q3: 1.40 m/s, P = .69; men, Q4: 1.65 m/s, Q1-Q3: 1.60 m/s; P = .39).

CONCLUSION

In healthy relatively high-functioning women and men, kyphosis severity was not associated with subsequent physical function. Individuals at risk of functional decline cannot be targeted based on supine CT thoracic curvature measures alone.