Insufficiency fractures of the spine in relation to cancellous bone density : An in vitro study

Schroder G, Flachsmeyer D, Kullen CM, et al. Insuffizienzfrakturen der Wirbelsäule in Abhängigkeit von der spongiösen Knochendichte. Orthopädie. 2022;51(7):547-555.BACKGROUND: The risk of osteoporotic insufficiency fractures (Fx) at the axial skeleton increases with decreasing bone density, with an accumulation in the thoracic and thoracolumbar regions. To better understand the differential distribution of Fx along the spine, morphological and osteodensitometric studies were performed by computed tomography (CT) in the various spine sections. In addition, we aimed to clarify whether Hounsfield units (HU) found on CT examinations from other indications correlate with bone density and could be grounds for osteologic diagnosis.; MATERIAL AND METHODS: The entire spines of 26body donors were fixed in aPlexiglas water phantom and analyzed by high-resolution spiral CT. In addition, CT morphological cancellous bone density was measured in HU from C3 to S2 (624 vertebral bodies). Bone mineral density (BMD, mg/ml) was calculated and used to estimate osteoporosis (OPO).; RESULTS: OPO was present in all spines. Significantly increased sintering fractures were found in the thoracic and thoracolumbar regions when BMD was below 60 mg/ml. Fx in the cervical spine area were not found overall. Cancellous bone density was significantly higher in the cervical (median 188.6 HU) than in the lumbar (median 63.6 HU) and sacral (median 25.5 HU) spine.; DISCUSSION: BMD loss of vertebral body cancellous bone leads to an increased risk of Fx, which is also found in the cadaver spines. However, an apparent threshold for the occurrence of sintering fractures is not undercut in the cervical region. Finding athreshold for HU would be relevant to clinical practice. © 2022. The Author(s).Hintergrund Das Risiko für osteoporotische Insuffizienzfrakturen (Fx) am Achsenskelett steigt mit zunehmender Abnahme der Knochendichte, wobei sich thorakal und thorakolumbal eine Häufung findet. Um die unterschiedliche Verteilung von Fx entlang der Wirbelsäule (WS) besser zu verstehen, wurden morphologische und osteodensitometrische Untersuchungen mittels Computertomographie (CT) in den verschiedenen WS-Abschnitten durchgeführt. Zudem war zu klären, ob die bei CT-Untersuchungen aus anderen Indikationen gefunden Hounsfield-Einheiten (HE) mit der Knochendichte korrelieren und Anlass für eine osteologische Diagnostik sein könnten. Material und Methoden Von 26 Körperspenden wurden die gesamten WS in einem Plexiglas-Wasser-Phantom fixiert und mittels hochauflösende Spiral-CT analysiert. Zusätzlich erfolgte die Messung der CT-morphologischen Spongiosadichte in HE von C3 bis S2 (624 Wirbelkörper). Der Knochenmineralgehalt (KMG, mg/ml) wurde ermittelt und zur Abschätzung einer Osteoporose (OPO) herangezogen. Ergebnisse Bei allen WS lag eine OPO vor. Bei einem KMG unterhalb von 60 mg/ml fanden sich signifikant vermehrte Sinterungsfrakturen im thorakalen und thorakolumbalen Bereich. Osteoporotische Insuffizienzfrakturen im HWS-Bereich fanden sich insgesamt nicht. Die Spongiosadichte war signifikant höher in den zervikalen (Median 188,6 HE) als in den lumbalen (Median 63,6 HE) und sakralen (Median 25,5 HE) Wirbelkörpern aller untersuchten WS. Schlussfolgerung Ein KMG-Verlust der Wirbelkörperspongiosa führt zu einem erhöhten Fx-Risiko, welches sich auch bei den verwendeten WS findet. Jedoch wird im zervikalen Bereich ein scheinbarer Schwellenwert für das Auftreten von Sinterungsfrakturen nicht unterschritten. Einen Schwellenwert für HE zu finden, wäre für die klinische Praxis relevant

Histomorphometric analysis of osteocyte density and trabecular structure of 92 vertebral bodies of different ages and genders

Schroeder G, Denkert K, Hiepe L, et al. Histomorphometric analysis of osteocyte density and trabecular structure of 92 vertebral bodies of different ages and genders. Annals of Anatomy - Anatomischer Anzeiger. 2023;246: 152022.Background: Knowledge of the histomorphometric structure of the vertebral body and factors influencing the structure is essential for a fundamental understanding of osteoporosis and osteoporotic fractures. The present study is focused on osteocyte density -a parameter seldom investigated so far - and trabecular width as well as bone area over tissue area in human vertebral bodies.Methods: Ninety-two vertebral body specimens (C5, C6, Th8, Th12, L1, L2) from 12 males and seven females were studied (Ethics Application Number A 2017-0072). The prepared vertebral specimens were extracted from the ventral aspect with a Jamshidi needle (R). The punches were decalcified and subsequently H&E stained. Using the Fiji/Image J program (version 1.53 f, Wayne Resband, National Institute of Mental Health, USA), osteocyte numbers were counted per calcified bone surface, and the trabecular width and bone area of trabecular bone were measured. The collected data were analyzed using the statistical software package SPSS, version 23.0 (SPSS Inc., Chicago, USA). Pearson's correlation coefficient was used for correlation analyses. Multiple linear regression analyses were also performed.Results: Osteocyte density did not differ significantly in comparisons based on gender and age (= 66 years). Men had wider trabeculae (p < 0.001) and a higher bone area over tissue area (BA/TA, %) (p = 0.025) than women. Individuals over 65 years of age had thinner trabeculae (p < 0.001) and a smaller BA/TA (%) (p < 0.001) than younger individuals. Multiple linear regression analyses were performed to determine the influence of 'gender' and 'age' on trabecular width and bone area over tissue area. The R2 was 0.388 for trabecular width and 0.227 for BA/TA (%). Per year of life, trabecular width decreases by 0.368 mu m (beta < 0.001) and BA/TA (%) by 0.001% (beta = 0.001). Men have on average 8.2 mu m wider trabeculae than women (beta = 0.035). A negative correlation (r = -0.275) was observed between trabecular width and osteocyte density. The wider the trabeculae, the fewer osteocytes per mm2 (p = 0.008). Conclusions: Surprisingly, we found no difference in osteocyte density with reference to age or gender. However, we did register significant age-and gender-related differences in bone area over tissue area and trabecular thickness. The age-related differences were more pronounced, implying that age-dependent loss of bone structure may be more important than differences between genders. (c) 2022 Elsevier GmbH. All rights reserved

Interobserver variability in the determination of bone mineral density in Hounsfield units from differently configured fields of measurement in the cancellous bone of vertebral bodies from elderly body donors

Schröder G, Andresen JR, Hiepe L, et al. Interobserver variability in the determination of bone mineral density in Hounsfield units from differently configured fields of measurement in the cancellous bone of vertebral bodies from elderly body donors. Journal of Orthopaedics. 2024;49:48-55.Background: Due to the absence of suitable diagnostic procedures, osteoporosis (OP) is frequently detected late or not at all. Many elderly persons undergo computed tomographies (CT). The routine determination of Hounsfield units (HU) in bone as a part of these examinations could close a gap here. Methods: Spines were extracted from 22 body donors, fixed in a PVC water phantom, and subjected to a highresolution CT investigation. Cancellous bone was examined and its bone mineral density measured in HU from cervical vertebra 3 to lumbar vertebra 5 (484 vertebral bodies). On sagittal sections, a circular and a rectangular region of interest (ROI) were defined in mid-vertebral cancellous bone, positioned manually, and the measurements were performed by three experienced radiologists. Bone mineral density (BMD), measured in mg/ cm(3), was used to determine the presence of OP.Results: All of the spines were osteoporotic. In the presence of a BMD below 60 mg/cm3 and HU values below 63.36 in lumbar vertebrae, there were significantly more vertebral body fractures in the thoracic and thoracolumbar spine. No difference was observed between the manually positioned circular and rectangular regions of interest (ROI) on the sagittal CT section (p > 0.05). Similar HU counts were obtained by the individual examiners (p > 0.05). The following formula was used to determine QCT values on a non-contrasted CT of the spine: QCT = 0.6 x HU + 13.7.Conclusions: Measurement of the density of cancellous bone in HU can be used to determine BMD for estimating demineralization. Quantitative BMD values in mg/cm3, which can be calculated from the HU data, concur well with QCT values

Breaking strength and bone microarchitecture in osteoporosis: a biomechanical approximation based on load tests in 104 human vertebrae from the cervical, thoracic, and lumbar spines of 13 body donors

Schroder G, Reichel M, Spiegel S, et al. Breaking strength and bone microarchitecture in osteoporosis: a biomechanical approximation based on load tests in 104 human vertebrae from the cervical, thoracic, and lumbar spines of 13 body donors. Journal of Orthopaedic Surgery and Research . 2022;17(1): 228.Background The purpose of the study was to investigate associations between biomechanical resilience (failure load, failure strength) and the microarchitecture of cancellous bone in the vertebrae of human cadavers with low bone density with or without vertebral fractures (VFx). Methods Spines were removed from 13 body donors (approval no. A 2017-0072) and analyzed in regard to bone mineral density (BMD), Hounsfield units (HU), and fracture count (Fx) with the aid of high-resolution CT images. This was followed by the puncture of cancellous bone in the vertebral bodies of C2 to L5 using a Jamshidi (TM) needle. The following parameters were determined on the micro-CT images: bone volume fraction (BVF), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), degree of anisotropy (DA), trabecular number (Tb.N), trabecular pattern factor (Tb.Pf), and connectivity density (Conn.D). The axial load behavior of 104 vertebral specimens (C5, C6, T7, T8, T9, T12, L1, L3) was investigated with a servohydraulic testing machine. Results Individuals with more than 2 fractures had a significantly lower trabecular pattern factor (Tb.Pf), which also proved to be an important factor for a reduced failure load in the regression analysis with differences between the parts of the spine. The failure load (FL) and endplate sizes of normal vertebrae increased with progression in the craniocaudal direction, while the HU was reduced. Failure strength (FS) was significantly greater in the cervical spine than in the thoracic or lumbar spine (p < 0.001), independent of sex. BVF, Tb.Th, Tb.N, and Conn.D were significantly higher in the cervical spine than in the other spinal segments. In contrast, Tb.Sp and Tb.Pf were lowest in the cervical spine. BVF was correlated with FL (r = 0.600, p = 0.030) and FS (r = 0.763, p = 0.002). Microarchitectural changes were also detectable in the cervical spine at lower densities. Conclusions Due to the unique microarchitecture of the cervical vertebrae, fractures occur much later in this region than they do in the thoracic or lumbar spine. Trial registration Approval no. A 2017-0072

Regional variations in the intra- and intervertebral trabecular microarchitecture of the osteoporotic axial skeleton

Schröder G, Baginski AM, Schulze M, et al. Regional variations in the intra- and intervertebral trabecular microarchitecture of the osteoporotic axial skeleton. Anatomical Science International . 2023: s12565-023-00726-6.Trabecular structures in vertebral bodies are unequally distributed in the cervical, thoracic and lumbar spine, and also within individual vertebrae. Knowledge of the microstructure of these entities could influence our comprehension and treatment of osteoporotic fractures, and even surgical procedures. Appropriate investigations may clarify the pathomechanisms of various osteoporotic fractures (fish, wedge-shaped, and flat vertebrae). We obtained three cancellous bone cylinders from the centers and margins of cervical vertebra 3 to lumbar vertebra 5, and investigated these in regard of bone volume fraction, trabecular thickness, separation, trabecular number, trabecular bone pattern factor, connectivity density, and degree of anisotropy. Using a Jamshidi-needle (R), we obtained samples from three quadrants (QI: right-sided edge, QII: central, QIII: left-sided edge) of 242 prepared vertebrae, and investigated these on a micro-CT device. In all, 726 bone samples were taken from eleven body donors. Bone volume fraction, trabecular thickness, and the degree of anisotropy were significantly lower in QII than in QI and QIII. Trabecular pattern factor, however, was significantly higher in QII than in QI and QIII. The results helped to explain fish vertebrae. Wedge fractures and flat vertebrae are most likely caused by the complex destruction of trabecular and cortical structures. The higher bone volume fraction in the cervical spine compared to the thoracic and lumbar spine accounts for the small number of fractures in the cervical spine. The marked trabecular pattern factor in the center of thoracic and lumbar vertebrae could be a reason for the surgeon to use different screw designs for individual vertebrae

Correction: Why Insufficiency Fractures are Rarely Found in the Cervical Spine, Even with Osteoporosis

Schroder G, Hiepe L, Moritz M, et al. Erratum: Warum sich in der Halswirbelsäule auch bei Osteoporose nur selten Insuffizienzfrakturen finden. Zeitschrift fur Orthopadie und Unfallchirurgie. 2022.Im oben genannten Artikel wurde in der Tabelle 2 der Tabellenkopf nicht richtig dargestellt. Dies wurde bereinigt.In the above-mentioned article, the table header in Table 2 was not displayed correctly. This has been corrected. The correction was made in the online version of the article on: 08.02.202