Vertebral Body Compressive Strength Evaluated by Dual-Energy X-Ray Absorptiometry and Hounsfield Units In Vitro

Cervical Vertebra Bone Quality Score Predicts Zero-Profile Anchored Spacer Interbody Fusion Cage Subsidence after Anterior Cervical Diskectomy and Fusion: A Retrospective Study

Study DesignRetrospective study.ObjectiveThis retrospective study primary focus is to investigate the relationship between the C-VBQ score and the occurrence of postoperative zero-profile anchored spacer (ROI-C) interbody fusion cage subsidence. Additionally, we aim to evaluate the predictive efficacy of the C-VBQ scoring system for subsidence in the context of ACDF with the ROI-C.MethodsPatients who underwent ACDF with the ROI-C cage at our hospital between January 2016 and December 2022 were included in this study. Univariate analysis and multivariate logistic regression were employed to identify independent risk factors associated with ROI-C cage subsidence after ACDF. Pearson correlation analysis was utilized to assess the correlation between the C-VBQ score and the height of ROI-C cage subsidence.ResultsA total of 102 patients underwent ACDF with ROI-C in our hospital were included in this study. Univariate analysis showed that age (P = 0.021) and C-VBQ score (P < 0.001) were the influencing factors of cage subsidence. Pearson correlation analysis showed that there was a significant positive correlation between the subsidence height of ROI-C cage and C-VBQ (r = 0.55, P < 0.01). Multivariate binary logistic regression analysis showed that C-VBQ score was the only variable that could significantly predict the subsidence of ROI-C cage after ACDF. Higher C-VBQ score was significantly associated with cage subsidence (P < 0.001).The AUC was 0.89, and the cutoff value for C-VBQ was 2.70.ConclusionThe findings indicate a significant correlation between a higher C-VBQ score before surgery and ROI-C cage subsidence after ACDF. The preoperative assessment of C-VBQ proves valuable for clinicians, enabling them to identify patients with low bone mineral density and predict the risk of zero-profile anchored spacer interbody fusion cage subsidence following ACDF.

Evaluating bone mineral density in osteoporotic vertebral compression fractures: the clinical utility of anterior column Hounsfield units

Study Design

Retrospective radiological analysis.

Objective

This study aimed to evaluate the clinical utility of anterior column Hounsfield units (HU) in assessing bone mineral density (BMD) in patients with osteoporotic vertebral compression fractures (OVCFs) and to investigate its potential advantages over traditional measurement methods.

Method

In this retrospective study, we analyzed data from 106 patients with acute OVCFs treated between January 2020 and June 2024. Inclusion criteria encompassed single-segment fractures from T10 to L2, with clear imaging results. HU values were measured from computed tomography (CT) scans, specifically targeting the anterior column of the vertebral body. Interobserver reliability was assessed via intraclass correlation coefficients (ICCs). Correlations between HU values, dual-energy X-ray absorptiometry (DEXA) results, and vertebral compression degrees were analyzed using Pearson correlation and receiver operating characteristic (ROC) curve analysis.

Results

The average HU values were significantly lower in the anterior column (50.39 ± 21.62 HU) compared to the middle column (63.12 ± 25.14 HU). The anterior column HU values showed a strong positive correlation with DEXA T-scores (r = 0.643) and BMD (r = 0.656). The degree of vertebral compression also correlated positively with both HU values and DEXA results, with the anterior column HU demonstrating the highest correlation (r = 0.727). ROC analysis indicated that the anterior column HU value had the largest area under the curve (AUC = 0.913) for predicting severe OVCFs, with an optimal cutoff of 59.07 HU.

Conclusion

The anterior column HU value serves as a superior predictor of BMD in patients with OVCFs compared to traditional methods. This study highlights the potential of using anterior column HU measurements to guide clinical decision-making regarding treatment options for OVCF patients, suggesting a shift towards more nuanced assessment strategies in osteoporosis management. Further research with larger sample sizes is warranted to validate these findings and explore the comprehensive application of HU values in osteoporosis evaluation.

Poor bony density can independently trigger higher incidence of adjacent vertebral fracture after percutaneous vertebralplasty: a mono-center retrospective study

OBJECTIVE

Symptomatic adjacent vertebral fractures (AVF) poses a challenge to patient prognosis in osteoporotic vertebral compressive fractures (OVCF) treated by percutaneous vertebralplasty (PVP). This study aimed to identify potential risk factors for AVF, thereby offering theoretical insights for refining patient management strategies and surgical protocols.

METHODS

Clinical data of PVP patients treated between March 2018 and May 2020 were retrospectively analyzed, with an average follow-up period of 30 months. Patients were stratified into two groups based on the presence or absence of recurrent symptomatic AVF. Demographic characteristics and imaging based parameters were assessed to identify potential risk factors for AVF.

RESULTS

Demographic parameters, including age, sex, body mass index, and fracture location (junctional or non-junctional), did not significantly differ between the two groups and were not found to be independent risk factors for AVF. However, patients with AVF exhibited significantly lower bone mineral density, as assessed by T-score and Hounsfield unit (HU) values. Notably, lower HU values emerged as an independent risk factor for AVF. Contrary to expectations, larger vertebral distraction and intervertebral disc cement leakage did not trigger higher incidence of AVF.

CONCLUSION

Progression of bony density reduction emerged as the primary driver for the heightened incidence of AVF. Accordingly, anti-osteoporosis therapy should be regarded as an effective strategy for mitigating the risk of AVF in patients undergoing PVP.

The Bony Density of the Pedicle Plays a More Significant Role in the Screw Anchorage Ability Than Other Regions of the Screw Trajectory

OBJECTIVE

Osteoporosis is a crucial risk factor for screw loosening. Our studies indicate that the bone mineral density (BMD) in the screw trajectory is a better predictor of screw loosening than the BMD of the lumbar spine or the screw insertion position. Research has shown that anchorage on the screw tip is the most significant factor for screw anchorage ability, while others argue that decreased bony quality in the pedicle poses a significant risk for screw loosening. This study aimed to determine whether the bony quality of the screw tip, pedicle, or screw-anchored vertebral body plays the most significant role in screw anchorage ability.

METHODS

A total of 73 patients who underwent single-segment bilateral pedicle screw fixation, along with posterior and transforaminal lumbar interbody fusion (PLIF and TLIF), from March 2019 to September 2020 were included in this retrospective study. The Hounsfield unit (HU) value of the fixed vertebral bodies, the entire screw trajectory, screw tip, screw-anchoraged vertebral body, and pedicles were measured separately. Data from patients with and without screw loosening were compared, and regression analyses were conducted to identify independent risk factors. Additionally, the area under the curve (AUC) values were computed to assess the predictive performance of different parameters. Furthermore, fixation strength was calculated in numerical models with varying bony densities in different regions.

RESULTS

HU values were found to be significantly lower in the loosening group across most measuring methods (HU values in the pedicle, 148.79 ± 97.04, 33.06 ± 34.82, p < 0.001). Specifically, the AUC of screw loosening prediction was notably higher when using HU values of the pedicle compared to other methods (AUC in the pedicle > 0.9 and in the screw insertion position > 0.7). Additionally, computational results for fixation strength revealed a clear decline in screw anchorage ability in models with poor BMD in the pedicle region.

CONCLUSIONS

Pedicle bone quality plays a more significant role in screw anchorage ability than that in other regions. The innovation of bony augmentation strategies should pay more attention to this region to optimize the screw anchorage ability effectively.

Hounsfield unit for assessing bone mineral density distribution within lumbar vertebrae and its clinical values

Study Design

Retrospective radiological analysis.

Objective

The aim of this study is to evaluate the distribution of bone mineral density (BMD) in lumbar vertebrae using the Hounsfield unit (HU) measurement method and investigate the clinical implications of HU values for assessing lumbar vertebrae BMD.

Method

Two hundred and ninety-six patients were retrospectively reviewed and divided into six groups according to age: Group 1(20-29 years old), Group 2 (30-39 years old), Group 3 (40-49 years old), Group 4 (50-59 years old), Group 5 (60-69 years old), Group 6 (70-79 years old). Six different locations from each vertebra of L1-L5 were selected as regions of interest: the anterior, middle and posterior parts of the upper and lower slices of the vertebrae. HU values were measured for the six regions of interest, followed by statistical analysis.

Results

The HU values of vertebrae showed a decreasing trend from young patients to elderly patients in Group 1 to Group 5. There was no significant difference in HU values among different vertebrae in the same age group. In all age groups, the HU values of the anterior and posterior part of the vertebral body were significantly different from L1 to L3, with the anterior part of the vertebral body having lower HU values than the posterior part. The HU values of the anterior and posterior part of the vertebral body of L4 and L5 were statistically significant only in Group 5 and Group 6, and the HU values of the anterior part of the vertebral body were lower than those of the posterior part. The HU values of posterior part of L4 and L5 in Group6 were higher than those in Group5.

Conclusion

Bone mineral density in the lumbar vertebrae is not uniformly distributed, potentially attributed to varying stress stimuli. The assessment of local HU values in the lumbar spine is of significant importance for surgical treatment.

Stepwise reduction of bony density in patients induces a higher risk of annular tears by deteriorating the local biomechanical environment

BACKGROUND CONTEXT

The relationship between osteoporosis and intervertebral disc degeneration (IDD) remains unclear. Considering that annular tear is the primary phenotype of IDD in the lumbar spine, the deteriorating local biomechanical environment may be the main trigger for annular tears.

PURPOSE

To investigate whether poor bone mineral density (BMD) in the vertebral bodies may increase the risk of annular tears via the degradation of the local biomechanical environment.

STUDY DESIGN

This study was a retrospective investigation with relevant numerical mechanical simulations.

PATIENT SAMPLE

A total of 64 patients with low back pain (LBP) and the most severe IDD in the L4-L5 motion segment were enrolled.

OUTCOME MEASURES

Annulus integration status was assessed using diffusion tensor fibre tractography (DTT). Hounsfield unit (HU) values of adjacent vertebral bodies were employed to determine BMD. Numerical simulations were conducted to compute stress values in the annulus of models with different BMDs and body positions.

METHODS

The clinical data of the 64 patients with low back pain were collected retrospectively. The BMD of the vertebral bodies was measured using the HU values, and the annulus integration status was determined according to DTT. The data of the patients with and without annular tears were compared, and regression analysis was used to identify the independent risk factors for annular tears. Furthermore, finite element models of the L4-L5 motion segment were constructed and validated, followed by estimating the maximum stress on the post and postlateral interfaces between the superior and inferior bony endplates (BEPs) and the annulus.

RESULTS

Patients with lower HU values in their vertebral bodies had significantly higher incidence rates of annular tears, with decreased HU values being an independent risk factor for annular tears. Moreover, increased stress on the BEP-annulus interfaces was associated with a stepwise reduction of bony density (ie, elastic modulus) in the numerical models.

CONCLUSIONS

The stepwise reduction of bony density in patients results in a higher risk of annular tears by deteriorating the local biomechanical environment. Thus, osteoporosis should be considered to be a potential risk factor for IDD biomechanically.

Estimation of bone mineral density with hounsfield unit measurement

OBJECTIVE

Although dual-energy x-ray absorptiometry (DXA) remains the gold standard for the measurement of bone mineral density (BMD), degenerative spine and spinal instrumentation yields inaccurate results, warranting the need for optional methods.

METHODS

Surgical options depend on the BMD of the patients, and to accommodate this need, we compared Hounsfield unit (HU) measurements obtained from computed tomography (CT) scans with the T-scores obtained from DXA scans to inquire whether HU measurements can screen for BMD. In this study, we also evaluated the relationship between body mass index and spontaneous fractures.

RESULTS

Based on the findings described in this study, we provide evidence that HU measurements obtained from CT scans can predict BMD.

CONCLUSIONS

This, therefore, allows HU measurements to be used as an effective diagnostic method in lieu of DXA scans when deciding on appropriate management of therapy for patients with spinal instrumentation or degenerative spines.

IVD fibrosis and disc collapse comprehensively aggravate vertebral body disuse osteoporosis and zygapophyseal joint osteoarthritis by posteriorly shifting the load transmission pattern

BACKGROUND

Disuse is a typical phenotype of osteoporosis, but the underlying mechanism has yet to be identified in elderly patients. Disc collapse and intervertebral disc (IVD) fibrosis are two main pathological changes in IVD degeneration (IDD) progression, given that these changes affect load transmission patterns, which may lead to disuse osteoporosis of vertebral bodies and zygapophyseal joint (ZJ) osteoarthritis (ZJOA) biomechanically.

METHODS

Clinical data from 59 patients were collected retrospectively. Patient vertebral bony density, ZJOA grade, and disc collapse status were judged via CT. The IVD fibrosis grade was determined based on the FA measurements. Regression analyses identified potential independent risk factors for osteoporosis and ZJOA. L4-L5 numerical models with and without disc collapse and IVD fibrosis were constructed; stress distributions on the bony endplate (BEP) and zygapophyseal joint (ZJ) cartilages were computed in models with and without disc collapse and IVD fibrosis.

RESULTS

A significantly lower disc height ratio and significantly greater FA were recorded in patients with ZJOA. A significant correlation was observed between lower HU values and two parameters related to IDD progression. These factors were also proven to be independent risk factors for both osteoporosis and ZJOA. Correspondingly, compared to the intact model without IDD. Lower stress on vertebral bodies and greater stress on ZJOA can be simultaneously recorded in models of disc collapse and IVD fibrosis.

CONCLUSIONS

IVD fibrosis and disc collapse simultaneously aggravate vertebral body disuse osteoporosis and ZJOA by posteriorly shifting the load transmission pattern.

Screw Insertional Torque Measurement in Spine Surgery: Correlation With Bone Mineral Density and Hounsfield Unit

OBJECTIVE

Achieving successful fusion during spine surgery is dependent on rigid pedicle screw fixation. To assess fixation strength, the insertional torque can be measured during intraoperative screw fixation. This study aimed to explore the technical feasibility of measuring the insertional torque of a pedicle screw, while investigating its relationship with bone density.

METHODS

Thoraco-lumbar screw fixation fusion surgery was performed on 53 patients (mean age, 65.5 ± 9.8 years). The insertional torque of 284 screws was measured at the point passing through the pedicle using a calibrated torque wrench, with a specially designed connector to the spine screw system. The Hounsfield units (HU) value was determined by assessing the trabecular portion of the index vertebral body on sagittal computed tomography images. We analyzed the relationship between the measured insertional torque and the following bone strength parameters: bone mineral density (BMD) and HU of the vertebral body.

RESULTS

The mean insertion torque was 105.55 ± 58.08 N∙cm and T-score value (BMD) was -1.14 ± 1.49. Mean HU value was 136.37 ± 57.59. Screw insertion torque was positively correlated with BMD and HU in whole patients. However, in cases of osteopenia, all variables showed very weak correlations with insertional torque. In patients with osteoporosis, there was no statistically significant correlation between BMD and torque strength; HU showed a significant correlation.

CONCLUSION

The insertional torque of screw fixation significantly correlated with bone density (BMD and HU). HU measurements showed greater clinical significance than did BMD values in patients with osteoporosis.

The cranial vertebral body suffers a higher risk of adjacent vertebral fracture due to the poor biomechanical environment in patients with percutaneous vertebralplasty

BACKGROUND CONTEXT

Adjacent vertebral fracture (AVF), a frequent complication of PVP, is influenced by factors such as osteoporosis progression, increased intervertebral cement leakage (ICL), and biomechanical deterioration. Notably, the risk of AVF is notably elevated in the cranial vertebral body compared with the caudal counterpart. Despite this knowledge, the underlying pathological mechanism remains elusive.

PURPOSE

This study delves into the role of biomechanical deterioration as a pivotal factor in the heightened risk of AVF in the cranial vertebral body following PVP. By isolating this variable, we aim to unravel its prominence relative to other potential risk factors.

STUDY DESIGN

A retrospective study and corresponding numerical mechanical simulations.

PATIENT SAMPLE

Clinical data from 101 patients treated by PVP were reviewed in this study.

OUTCOME MEASURES

Clinical assessments involved measuring Hounsfield unit (HU) values of adjacent vertebral bodies as a representation of patients' bone mineral density (BMD). Additionally, the rates of ICL were compared among these patients. Numerical simulations were conducted to compute stress values in the cranial and caudal vertebral bodies under various body positions.

METHODS

In a retrospective analysis of PVP patients spanning July 2016 to August 2019, we scrutinized the HU values of adjacent vertebral bodies to discern disparities in BMD between cranial and caudal regions. Additionally, we compared ICL rates on both cranial and caudal sides. To augment our investigation, well-validated numerical models simulated the PVP procedure, enabling the computation of maximum stress values in cranial and caudal vertebral bodies across varying body positions.

RESULTS

The incidence rate of cranial AVF was significantly higher than the caudal side. No notable distinctions in HU values or ICL rates were observed between the cranial and caudal sides. The incidence of AVF showed no significant elevation in patients with ICL in either region. However, numerical simulations unveiled heightened stress values in the cranial vertebral body.

CONCLUSIONS

In patients postPVP, the cranial vertebral body faces a heightened risk of AVF, primarily attributed to biomechanical deterioration rather than lower BMD or an elevated ICL rate.

Evaluating bone quality and asymmetrical aplasia of the thoracic vertebral body in Lenke 1A adolescent idiopathic scoliosis using hounsfield units

Study Design

Retrospective analysis.

Objective

To evaluate bone quality and investigate asymmetrical development of the thoracic vertebral body in adolescent idiopathic scoliosis (AIS) based on Hounsfield unit (HU) measurements obtained from computed-tomography (CT) scans.

Summary of Background Data

HU value demonstrated higher reliability and accuracy than the traditional method, indicating that they could be used to individually evaluate and effectively assess the bone quality of every vertebra in the CT films.

Methods

Total 30 AIS patients classified as Lenke Type 1A and 30 paired controls were included in this study. Regions of interest for HU value were measured on three horizontal images of the thoracic vertebrae. HU measurements of the whole vertebral body in each vertebra were obtained. Using HU value, we separately measured the concave and convex sides of each vertebral body in patients' group, as well as within the left and right sides in controls.

Results

In controls, the mean HU value of T1–T12 thoracic vertebral bodies was 240.03 ± 39.77, with no statistical differences among different levels. As for AIS patients, in the structural curve, the apical region had a significantly lower HU compared with the other regions, and asymmetrical change was found between the concave and convex sides, most significantly in the apical region. In the non-structural curve, the average HU value was 254.99 ± 44.48, and no significant difference was found either among the different levels of vertebrae or between the concave and convex sides.

Conclusions

Abnormal and asymmetrical changes in bone quality of the thoracic vertebral body in patients with Lenke 1A AIS were indicated. Low bone quality in the convex side of the structural curve indicated stronger internal fixation in surgery to correct the deformity.

The association between paraspinal muscle degeneration and osteoporotic vertebral compression fracture severity in postmenopausal women

BACKGROUND

According to reports in the literature, osteoporotic vertebral compression fracture (OVCF) is associated with paraspinal muscle degeneration; however, the association between the severity of OVCF and paraspinal muscle degeneration is not clear.

OBJECTIVE

The purpose of this study was to investigate the association between paraspinal muscle degeneration and OVCF severity in postmenopausal women.

METHODS

Three hundred and seventy-six MRI images from 47 patients were collected and analyzed. Sagittal and axial coronal T2-weighted images were used to measure the fractured vertebra sagittal cross-sectional area (FSCSA), the adjacent normal vertebral body sagittal cross-sectional area (NSCSA), paraspinal muscle cross-sectional area (CSA), and the fat cross-sectional area (FCSA). The ratio of fractured vertebra compressed sagittal cross-sectional area (RCSA) and fatty infiltration ratio (FIR) was subsequently calculated. The formulas for RCSA and FIR calculations are as follows: RCSA = (NSCSA-FSCSA)/NSCSA; FIR = FCSA/CSA. RCSA and FIR represent the severity of OVCF and paraspinal muscle degeneration, respectively.

RESULTS

The correlation between paraspinal muscle degeneration and OVCF severity was analyzed using the Pearson correlation, and multiple regression analysis was performed to explore related risk factors. OVCF severity was closely associated with paraspinal muscle degeneration (L3/4 FIR r= 0.704, P< 0.05; L4/5 FIR r= 0.578, P< 0.05; L5/S1 FIR r= 0.581, P< 0.05). Multiple regression analysis demonstrated that the risk factor for OVCF severity was L3/4 FIR (β= 0.421, P= 0.033).

CONCLUSION

OVCF severity was associated with the FIR of paraspinal muscles, and L3/4 FIR was a predictive factor for OVCF severity in postmenopausal women.

Significance of Cervical Spine Computed Tomography Hounsfield Units to Predict Bone Mineral Density and the Subsidence After Anterior Cervical Discectomy and Fusion

STUDY DESIGN

This study was a retrospective review.

OBJECTIVE

The purpose of this study was to investigate the correlation analysis between Hounsfield units (HU) and dual x-ray absorptiometry (DXA) based on the clinical results of patients who underwent anterior cervical discectomy and fusion (ACDF) surgery.

SUMMARY OF BACKGROUND DATA

There is no technique to directly measure bone mineral density (BMD) in the cervical spine. As computed tomography is a very popular preoperative planning modality, using the HU value from that analysis to predict osteoporosis is important for patient outcomes and applications in the clinical field.

MATERIALS AND METHODS

We reviewed the records for 235 patients who underwent 1-level (n=120) or 2-level (n=115) ACDF surgery. In the 1-level ACDF group, the HU was measured from C3 to C6 vertebra, while that for the 2-level ACDF group was measured from 3 surgical index vertebrae. The correlation patterns were analyzed with the corresponding DXA (T-score) for each patient. Subsidence of fusion segment was defined as change in distance between plate-tip and upper (lower) margin of the vertebra (index level) after 4 months of follow-up. In addition, to determine the relevant factors that influence fusion segment subsidence, other preoperative (C2 slope, C7 slope, C2-C7 angle, and C2-C7 sagittal vertical axis) and postoperative parameters (coronal angle and segmental angle change) were measured.

RESULTS

The correlation coefficient between HU and DXA ranged from 0.57 to 0.71 in the 1-level ACDF group and from 0.59 to 0.66 in the 2-level ACDF group. The correlation between HU and DXA was statistically significant regardless of the degree of anterior osteophyte (r=-0.65 to 0.78). Total subsidence height was 3.8 mm after ACDF, and both HU and DXA were statistically correlated with total subsidence (r=0.26-0.28). In multivariate analysis, HU (middle vertebra) value was statistically associated with the degree of total subsidence. The high-subsidence group (≥4.5 mm) showed smaller HU values (284.1 vs. 316.0) and T-scores (-0.5 vs. 0.1) compared to the low-subsidence group (<4.5 mm). The discrepancy group, defined as cases with excess plate shift on 1 side, also showed smaller HU values (260.4 vs. 312.4) and higher degrees of total subsidence than the matched group.

CONCLUSIONS

The correlation between HU in cervical computed tomography and lumbar DXA (T-score) was statistically significant in both 1-level and 2-level ACDF. The level of BMD (HU or DXA) is a very important factor for clinically determining the amount and regularity of subsidence after ACDF. Therefore, HU can be a good alternative assessment to accurately reflect as much of the BMD degree as DXA in the cervical spine.

Hounsfield Unit for Assessing Vertebral Bone Quality and Asymmetrical Vertebral Degeneration in Degenerative Lumbar Scoliosis

STUDY DESIGN

Retrospective analysis.

OBJECTIVES

The aim of this study was to demonstrate the correlation between degenerative lumbar scoliosis (DLS) and osteoporosis based on Hounsfield unit (HU) measurement from computed tomography (CT) scans, and to investigate the asymmetrical vertebral degeneration in DLS.

SUMMARY OF BACKGROUND DATA

The correlation between DLS and osteoporosis measured by dual-energy x-ray absorptiometry (DEXA) is debated, since T-scores measured by DEXA scan can be overestimated due to abdominal vessel wall calcification, degenerative bony spurs, and facet hypertrophy. The reliability and accuracy of HU to determine osteoporosis are shown in many reports, but it has never been used to assess the vertebral bone quality for DLS patients.

METHODS

Nighty-five DLS patients were retrospectively reviewed. Regions of interest for HU were measured on three coronal images of the lumbar vertebrae. HU measurement of the whole vertebrae from L1 to L5 was obtained, then HU measurement within concave and convex sides were obtained separately in L5, upper and lower end vertebrae, apex vertebrae, neutral vertebrae, stable vertebrae.

RESULTS

HU value presented a gradually increasing trend from L1 to L5. No correlation was detected between Cobb angle and mean HU value of the 5 lumbar vertebrae, or between Cobb angle and HU value of every lumbar vertebrae separately. HU value was higher within concavity than that within convexity of the same vertebrae both in major and compensatory curve. Asymmetric HU ratio in apex vertebrae positively correlated with Cobb angle. Stable vertebrae were the first proximal vertebrae that present opposite orientation of asymmetric HU ratio from the other lumbar vertebrae.

CONCLUSION

Progression of degenerative scoliosis presents no correlation with osteoporosis based on HU measurement but could increase the asymmetrical vertebral degeneration, especially in apex vertebrae. Distraction of the pedicle screws at concave side, instead of compression of pedicle screws at convex side, should be a priority to correct lumbosacral curve.

LEVEL OF EVIDENCE

3.

Predicting experimentally-derived failure load at the distal radius using finite element modelling based on peripheral quantitative computed tomography cross-sections (pQCT-FE): A validation study

Dual energy X-ray absorptiometry, the current clinical criterion method for osteoporosis diagnosis, has limitations in identifying individuals with increased fracture risk, especially at the distal radius. Peripheral quantitative computed tomography (pQCT) can provide volumetric bone density data, as well as information on bone geometry, which makes it possible to establish finite element (FE) models of the distal radius from which bone strength and stiffness can be calculated. In this study, we compared experimental mechanical failure load data of the forearm with pQCT- based FE (pQCT-FE) modelling properties. Sixteen cadaveric forearm specimens were experimentally loaded until failure. Estimated stiffness and strength variables of compression, shear, bending and torsion were calculated from pQCT-FE modelling of single cross-sections of 0.2 × 0.2 × 2.4 mm of the radius pQCT image. A moderate-to-strong coefficient of determination (r²) was observed between experimental failure load and pQCT-FE variables. The highest r² was observed for bending stiffness (r² = 0.83). This study validates the use of pQCT-FE in the assessment of distal radius bone strength for future studies.