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

Guido Schröder; Martin Reichel; Sven Spiegel; Marko Schulze; Andreas Götz; Semjon Bugaichuk; Julian Ramin Andresen; Claus Maximilian Kullen; Reimer Andresen; Hans-Christof Schober

doi:10.1186/s13018-022-03105-5

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

J Orthop Surg Res. 2022 Apr 11;17(1):228. doi: 10.1186/s13018-022-03105-5.

Authors

Affiliations

¹ Clinic of Orthopedics and Trauma Surgery, Warnow Klinik, 18246, Buetzow, Germany. guido.schroeder1@gmx.net.
² Faculty of Engineering and Marine Engineering, Chair of Engineering Design/Lightweight Construction, University of Rostock, Rostock, Germany.
³ Medical Faculty, University of Rostock, Rostock, Germany.
⁴ Institute for Anatomy and Cell Biology, University of Bielefeld, Bielefeld, Germany.
⁵ Institute for Biomedical Engineering, Medical University of Rostock, Rostock, Germany.
⁶ University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.
⁷ Medical School, Sigmund Freud University, Vienna, Austria.
⁸ Institute of Diagnostic and Interventional Radiology/Neuroradiology, Academic Teaching Hospital of the Universities of Kiel, Luebeck and Hamburg, Westkuestenklinikum Heide, Heide, Germany.
⁹ Department of Internal Medicine IV, Municipal Hospital Suedstadt Rostock, Academic Teaching Hospital of the University of Rostock, Rostock, Germany.

Abstract

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™ 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.

Keywords: Biomechanics; Computed tomography; Insufficiency fracture; Osteoporosis; Spine; X-ray microtomography.

MeSH terms

Bone Density
Cervical Vertebrae
Humans
Lumbar Vertebrae / diagnostic imaging
Osteoporosis* / diagnostic imaging
Spinal Puncture*
Thoracic Vertebrae / diagnostic imaging
X-Ray Microtomography