Related Experiment Video
Updated: Sep 29, 2025
Author Spotlight: Enhancing Small Animal Bone Compression Testing for Research
Published on: December 1, 2023
Vertebral Bone Mineral Density, Vertebral Strength, and Syndesmophyte Growth in Ankylosing Spondylitis: The
Sovira Tan1, Hadi Bagheri2, David Lee3
1National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, Maryland.
Objective:
To examine the relationship between vertebral trabecular bone mineral density (tBMD), vertebral strength, and syndesmophytes in patients with ankylosing spondylitis (AS) using quantitative computed tomography (QCT).
Methods:
We performed QCT of the spine to measure syndesmophytes and tBMD in 5 vertebrae (T11-L3) in 61 patients with AS. Finite element analysis was performed to measure vertebral strength in compressive overload, including in trabecular and cortical compartments. In cross-sectional analyses, we examined associations of syndesmophyte height with tBMD and vertebral strength in each vertebra. In 33 patients followed up for 2 years, we investigated whether baseline tBMD and vertebral strength predicted syndesmophyte growth in the same vertebra, and vice versa.
Results:
In the cross-sectional analyses, 126 vertebrae had bridging, 77 vertebrae had nonbridging syndesmophytes, and 83 vertebrae had no syndesmophytes. There were strong inverse associations between syndesmophyte height and tBMD, total strength, and trabecular strength only among bridged vertebrae. In the longitudinal analysis, nonbridged vertebrae with low tBMD (adjusted β = -0.01 [95% confidence interval (95% CI) -0.019, -0.0012]) and low strength (adjusted β = -0.0003 [95% CI -0.0004, -0.0002]) had more syndesmophyte growth over time. Similar associations were absent among bridged vertebrae. Conversely, vertebrae with bridging at baseline had a significant loss in percent tBMD over time (adjusted β = -0.001 [95% CI -0.0017, -0.0004]).
Conclusion:
Associations between syndesmophytes and vertebral density and strength in AS differ between bridged and nonbridged vertebrae. Among nonbridged vertebrae, low tBMD and strength are associated with syndesmophyte growth. Bridging is associated with large subsequent losses in tBMD, possibly due to mechanical offloading.
Related Concept Videos
01:29Bone Disorders
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
01:09Spongy Bone
Spongy bone is more porous, and less dense compared to compact bone. It is composed of concentric lamellae that are arranged irregularly to form the trabecular network. In some bones, the spaces between trabeculae contain red marrow, where...
01:09Changes in the Appendicular Skeleton with Age
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
01:30General Structure of a Vertebra
01:23Bone as Supporting Connective Tissue
Bone Matrix
Bone, or osseous tissue, is a connective tissue that has a large amount of two different types of matrix material. The organic matrix is similar to the matrix material found in other connective tissues, including some amount of collagen and elastic fibers. This gives strength and flexibility to the tissue. The inorganic matrix consists of mineral salts— mostly calcium salts—...
01:18The Bone Matrix