Cervical spine bone density in young healthy adults as a function of sex, vertebral level and anatomic location

Differences in vertebral bone density between African apes

OBJECTIVES

Low-energy vertebral fractures are a common health concern, especially in elderly people. Interestingly, African apes do not seem to experience as many vertebral fractures and the low-energy ones are even rarer. One potential explanation for this difference is the lower bone density in humans. Yet, only limited research has been done on the vertebral bone density of the great apes and these have mainly included only single vertebrae. Hence the study aim is to expand our understanding of the vertebral microstructure of African apes in multiple spinal segments.

MATERIALS

Bone density in the vertebral body of C7, T12, and L3 was measured from 32 Pan troglodytes and 26 Gorilla gorilla using peripheral quantitative computed tomography (pQCT).

RESULTS

There was a clear difference between the three individual vertebrae and consequently the spinal segments in terms of trabecular density and cortical density and thickness. The variation of these bone parameters between the vertebrae differed between the apes but was also different from those reported for humans. The chimpanzees were observed to have overall higher trabecular density, but gorillas had higher cortical density and thickness. Cortical thickness had a relatively strong association with the vertebral size.

DISCUSSION

Despite the similarity in locomotion and posture, the results show slight differences in the bone parameters and their variation between spinal segments in African apes. This variation also differs from humans and appears to indicate a complex influence of locomotion, posture, and body size on the different spinal segments.

Regional variations in C1-C2 bone density on quantitated computed tomography and clinical implications

Background

Our elderly population is growing and the number of spine fractures in the elderly is also growing. The elderly population in general may be considered as poor surgical candidates experience a high rate of fractures at C1 and C2 compared with the general population. Nonoperative management of upper cervical fractures is not benign as there is a high nonunion rate for both C1 and C2 fractures in the elderly, and orthosis compliance is often suboptimal, or complicated by skin breakdown. The optimal technique for upper cervical stabilization in the elderly may be different than in younger populations as the bone quality is inferior in the elderly. The objective of this basic science study is to determine whether the bone mineral density (BMD) of C1 and C2 vary by region, and if this is a gender difference in this elderly age group.

Methods

Twenty cadaveric spines from 45 to 83 years of age were used to obtain BMD using quantitated computed tomography (QCT). BMD was measured using a QCT. For C1, 8 regions were determined: anterior tubercle, bilateral anterior and medial lateral masses, bilateral posterior arches, and posterior tubercle. For C2, 7 regional BMDs were determined: top of odontoid, base of odontoid-body interface, mid body, bilateral lateral masses, anterior inferior body near the discs space, and the C2 spinous process.

Results

The BMD was greatest at the C1 anterior tubercle (564.4±175.8 mg/cm³) and C1 posterior ring (420.8±110.2 mg/cm³), and least at the anterior and medial lateral masses (262.8±59.5 mg/cm³, 316.9±72.6 mg/cm³). At C2 QCT BMD was greatest at the top of the dens (400.6±107.9 mg/cm³) decreasing down through the odontoid-C2 body junction (267.8±103.5 mg/cm³) and least in the mid C2 body 249.1±68.8 mg/cm³). The posterior arch of C1 and the spinous process of C2 had higher BMD's 420.8±110.2 mg/cm³ and 284.1±93.0 mg/cm³, respectively. A high correlation was observed between the BMD at the interface of the dens-vertebral body with the vertebral body with a Pearson correlation coefficient of 0.86. The BMD of the top of dens was significantly higher (p<.05) than all the regions in C2.

Conclusions

Regional and segmental BMD variations at C1 and C2 have clinical implications for surgical constructs in the elderly population. Given the higher BMDs of the C1 and C2 spinous process and posterior arches, consideration should be given to incorporate these areas using various C1-C2 wiring techniques. In the elderly, lateral masses particularly at C1 with lower BMD may result in potential screw loosening and nonunion in this age group. Old-school wiring techniques have a track record of efficacy and safety with less blood loss, reduced operative time, reduced X-ray exposure, and should be considered in the elderly as a primary stabilization technique or a belt-over suspenders approach based on regional variations in BMD in the elderly.

Comparison of bone density patterns of the subaxial spine between chimpanzees and gorillas - A case study

Case study on the bone density pattern of subaxial vertebral column in African apes.

INTRODUCTION

African apes have been noted to experience fewer back ailments than humans and to have higher vertebral bone density. Yet, research on the subject is quite limited and has usually included only one or few vertebrae. However, to understand vertebral column as whole and how posture and locomotion might have affected it, we need to know how bone density varies between adjacent vertebrae.

MATERIALS AND METHODS

Bone density in the vertebral body was measured for all subaxial vertebrae of five specimens including two Pan troglodytes (1 male and 1 female) and three Gorilla gorilla (2 males and 1 female) using peripheral quantitative computed tomography (pQCT).

RESULTS

The results tentatively indicated differences between species, especially in the trabecular density of the cervical segment and support the need for further studies on this subject.

Characterization of regional variation of bone mineral density in the geriatric human cervical spine by quantitative computed tomography

Background

Odontoid process fractures are among the most common in elderly cervical spines. Their treatment often requires fixation, which may include use of implants anteriorly or posteriorly. Bone density can significantly affect the outcomes of these procedures. Currently, little is known about bone mineral density (BMD) distributions within cervical spine in elderly. This study documented BMD distribution across various anatomical regions of elderly cervical vertebrae.

Methods and findings

Twenty-three human cadaveric C1-C5 spine segments (14 males and 9 female, 74±9.3 y.o.) were imaged via quantitative CT-scan. Using an established experimental protocol, the three-dimensional shapes of the vertebrae were reconstructed from CT images and partitioned in bone regions (4 regions for C1, 14 regions for C2 and 12 regions for C3-5). The BMD was calculated from the Hounsfield units via calibration phantom. For each vertebral level, effects of gender and anatomical bone region on BMD distribution were investigated via pertinent statistical tools.

Data trends suggested that BMD was higher in female vertebrae when compared to male ones. In C1, the highest BMD was found in the posterior portion of the bone. In C2, BMD at the dens was the highest, followed by lamina and spinous process, and the posterior aspect of the vertebral body. In C3-5, lateral masses, lamina, and spinous processes were characterized by the largest values of BMD, followed by the posterior vertebral body.

Conclusions

The higher BMD values characterizing the posterior aspects of vertebrae suggest that, in the elderly, posterior surgical approaches may offer a better fixation quality.

Aging Alters Cervical Vertebral Bone Density Distribution: A Cross-Sectional Study

Osteoporosis reduces bone mineral density (BMD) with aging. The incidence of cervical vertebral injuries for the elderly has increased in the last decade. Thus, the objective of the current study was to examine whether dental cone beam computed tomography (CBCT) can identify age and sex effects on volumetric BMD and morphology of human cervical vertebrae. A total of 136 clinical CBCT images were obtained from 63 male and 73 female patients (20 to 69 years of age). Three-dimensional images of cervical vertebral bodies (C2 and C3) were digitally isolated. A gray level, which is proportional to BMD, was obtained and its distribution was analyzed in each image. Morphology, including volume, heights, widths, and concavities, was also measured. Most of the gray level parameters had significantly higher values of C2 and C3 in females than in males for all age groups (p < 0.039). The female 60-age group had significant lower values of Mean and Low5 of C2 and C3 than both female 40- and 50-age groups (p < 0.03). The reduced BMD of the female 60-age group likely resulted from postmenopausal demineralization of bone. Current findings suggest that dental CBCT can detect age-dependent changes of cervical vertebral BMD, providing baseline information to develop an alternative tool to diagnose osteoporosis.

Proposed diagnostic volumetric bone mineral density thresholds for osteoporosis and osteopenia at the cervicothoracic spine in correlation to the lumbar spine

OBJECTIVES

To determine the correlation between cervicothoracic and lumbar volumetric bone mineral density (vBMD) in an average cohort of adults and to identify specific diagnostic thresholds for the cervicothoracic spine on the individual subject level.

METHODS

In this HIPPA-compliant study, we retrospectively included 260 patients (59.7 ± 18.3 years, 105 women), who received a contrast-enhanced or non-contrast-enhanced CT scan. vBMD was extracted using an automated pipeline ( https://anduin.bonescreen.de ). The association of vBMD between each vertebra spanning C2-T12 and the averaged values at the lumbar spine (L1-L3) was analyzed before and after semiquantitative assessment of fracture status and degeneration, and respective vertebra-specific cut-off values for osteoporosis were calculated using linear regression.

RESULTS

In both women and men, trabecular vBMD decreased with age in the cervical, thoracic, and lumbar regions. vBMD values of cervicothoracic vertebrae showed strong correlations with lumbar vertebrae (L1-L3), with a median Pearson value of r = 0.87 (range: r_C2 = 0.76 to r_T12 = 0.96). The correlation coefficients were significantly lower (p < 0.0001) without excluding fractured and degenerated vertebrae, median r = 0.82 (range: r_C2 = 0.69 to r_T12 = 0.93). Respective cut-off values for osteoporosis peaked at C4 (209.2 mg/ml) and decreased to 83.8 mg/ml at T12.

CONCLUSION

Our data show a high correlation between clinically used mean L1-L3 values and vBMD values elsewhere in the spine, independent of age. The proposed cut-off values for the cervicothoracic spine therefore may allow the determination of low bone mass even in clinical cases where only parts of the spine are imaged.

KEY POINTS

vBMD of all cervicothoracic vertebrae showed strong correlation with lumbar vertebrae (L1-L3), with a median Pearson's correlation coefficient of r = 0.87 (range: r_C2 = 0.76 to r_T12 = 0.96). The correlation coefficients were significantly lower (p < 0.0001) without excluding fractured and moderate to severely degenerated vertebrae, median r = 0.82 (range: r_C2 = 0.69 to r_T12 = 0.93). We postulate that trabecular vBMD < 200 mg/ml for the cervical spine and < 100 mg/ml for the thoracic spine are strong indicators of osteoporosis, similar to < 80 mg/ml at the lumbar spine.

Characteristics of Lumbar Bone Density in Middle-Aged and Elderly Subjects: A Correlation Study between T-Scores Determined by the DEXA Scan and Hounsfield Units from CT

Purpose

To describe the characteristics of lumbar bone density in middle-aged and elderly subjects and explore whether there is a correlation between computed tomography (CT) values and the bone mineral density (BMD) T-scores of the lumbar vertebral cancellous bone.

Methods

Forty-two subjects, including 25 males and 17 females, with a mean age of 56 years, who underwent BMD measurement and lumbar multislice spiral CT scan at the China Rehabilitation Research Center from January 2019 to December 2019 were selected. Dual-energy X-ray absorptiometry (DEXA) was applied to obtain the total BMD T-scores of the lumbar L1–L4 vertebrae.

Results

The CT values decreased from L1 to L4 and were 145.91 ± 8.686 HU, 143.18 ± 8.598 HU, 137.39 ± 8.276 HU, and 135.23 ± 8.219 HU, respectively. The total CT value of L1–L4 was 140.43 ± 4.199 HU. The mean total BMD T-score of L1–L4 was −0.94. The CT values of the L1–L4 vertebrae were positively correlated with the total BMD T-scores of L1–L4 (r = 0.349, P < 0.001). The CT value of the left third of the same vertebrae was the highest, and there was a strong positive correlation between the regional CT value of the lumbar spine and the entire vertebra CT values (r > 0.7).

Conclusion

The CT values of the lumbar spine can assist the measurement of the T-scores of lumbar BMD, which could aid in early opportunistic screening for osteopenia and preventing osteoporosis and vertebral compression fractures in middle-aged and elderly subjects. This trial is registered with ChiCTR2100049571.

Pedicle Screws Challenged: Lumbar Cortical Density and Thickness Are Greater in the Posterior Elements Than in the Pedicles

STUDY DESIGN

Controlled laboratory study.

OBJECTIVE

To measure the total bone mineral density (BMD), cortical volume, and cortical thickness in seven different anatomical regions of the lumbar spine.

METHODS

Using computed tomography (CT) images, 3 cadaveric spines were digitally isolated by applying filters for cortical and cancellous bone. Each spine model was separated into 5 lumbar vertebrae, followed by segmentation of each vertebra into 7 anatomical regions of interest using 3-dimensional software modeling. The average Hounsfield units (HU) was determined for each region and converted to BMD with calibration phantoms of known BMD. These BMD measurements were further analyzed by the total volume, cortical volume, and cancellous volume. The cortical thickness was also measured. A similar analysis was performed by vertebral segment. St Mary's Medical Center's Institutional Review Board approved this study. No external funding was received for this work.

RESULTS

The lamina and inferior articular process contained the highest total BMD, thickest cortical shell, and largest percent volumes of cortical bone. The vertebral body demonstrated the lowest BMD. The BMDs of the L4 and L5 segments were lower; however, there were no statistically significant differences in BMD between the L1-L5 vertebral segments.

CONCLUSION

Extrapedicular regions of the lumbar vertebrae, including the lamina and inferior articular process, contain denser bone than the pedicles. Since screw pullout strength relies greatly on bone density, the lamina and inferior articular processes may offer stronger fixation of the lumbar spine.

Regional bone mineral density differences measured by quantitative computed tomography in patients undergoing anterior cervical spine surgery

BACKGROUND CONTEXT

Clinically, the association between bone mineral density (BMD) and surgical instrumentation efficacy is well recognized. Although several studies have quantified the BMD of the human lumbar spine, comprehensive BMD data for the cervical spine is limited. The few available studies included young and healthy patient samples, which may not represent the typical cervical fusion patient. Currently no large scale study provides detailed BMD information of the cervical and first thoracic vertebrae in patients undergoing anterior cervical spine surgery.

PURPOSE

The objective of this study was to determine possible trabecular BMD variations throughout the cervical spine and first thoracic vertebra in patients undergoing anterior cervical discectomy and fusion (ACDF) and to assess the correlation between BMDs of the spinal levels C1-T1.

STUDY DESIGN/SETTING

This is a retrospective case series.

PATIENT SAMPLE

Patients undergoing ACDF from 2015 to 2018 at a single, academic institution with available preoperative CT imaging were included in this study.

OUTCOME MEASURES

The outcome measure was BMD measured by QCT.

METHODS

Patients that underwent ACDF from 2015 to 2018 at a single, academic institution were included in this study. Subjects with previous cervical instrumentation or missing/incomplete preoperative cervical spine CT imaging were excluded. Asynchronous quantitative computed tomography (QCT) measurements of the lateral masses of C1 and the C2-T1 vertebral bodies were performed. For this purpose, an elliptical region of interest that consisted exclusively of trabecular bone was selected. Any apparent sclerotic levels that might affect trabecular QCT measurements were excluded from the final analysis. Interobserver reliability of measurements was assessed by calculating the interclass correlation coefficients (ICC). Pairwise comparison of BMD was performed and correlations between the various cervical levels were evaluated. The statistical significance level was set at p<.05.

RESULTS

In all, 194 patients (men, 62.9%) met inclusion criteria. The patient population was 91.2% Caucasian with a mean age of 55.9 years and mean BMI of 28.2 kg/m². The ICC of cervical QCT measurements was excellent (ICC 0.92). The trabecular BMD was highest in the mid-cervical spine (C4) and decreased in the caudal direction (C1 average=253.3 mg/cm³, C2=276.6 mg/cm³, C3=272.2 mg/cm³, C4=283.5 mg/cm³, C5=265.1 mg/cm³, C6=235.3 mg/cm³, C7=216.8 mg/cm³, T1=184.4 mg/cm³). The BMD of C7 and T1 was significantly lower than those of all other levels. Nonetheless, significant correlations in BMD among all measured levels were observed, with a Pearson's correlation coefficient ranging from 0.507 to 0.885.

CONCLUSIONS

To the authors' knowledge this is the largest study assessing trabecular BMD of the entire cervical spine and first thoracic vertebra by QCT. The patient sample consisted of patients undergoing ACDF, which adds to the clinical relevance of the findings. Knowledge of BMD variation in the cervical spine might be useful to surgeons utilizing anterior cervical spine plate and screw systems. Due to the significant variation in cervical BMD, procedures involving instrumentation at lower density caudal levels might potentially benefit from a modification in instrumentation or surgical technique to achieve results similar to more cephalad levels.

Measurement bone mineral density (BMD) of patients with beta thalassemia

The aim of the study is determining bone mineral density (BMD) of Patients with beta thalassemia in order to find the prevalence and related factors on the conditions. Z-Score of femoral neck and lumbar vertebrae were reported comparing normal matched subjects. Age and bone mineral density were significantly correlated. Moreover, the disease had significantly higher severity in men than in women. A negative significant correlation was detected between BMD and the mean of hematocrit in the last 5 years. There was significant differences between sex hormone and bone density. A significant correlation between hydroxy urea and BMD were found. A significant relationship between the use of bisphosphonates and bone density were found. Osteopenia and osteoporosis were highly prevalent in our participants. Therefore, regular tests are required to examine bone mineral density in these patients. Furthermore, the exact effect of age on bone mineral density need to be clarified.