Mechanism of formation of intravertebral clefts in osteoporotic vertebral compression fractures: an in vitro biomechanical study

Publication date: Available online 31 July 2018

Source: The Spine Journal

Author(s): Wang Chongyan, Zhang Xuyang, Li Shengyun, Liu Junhui, Shan Zhi, Wang Jiasheng, Chen Jian, Fan Shunwu, Zhao Fengdong

Abstract

Background context

Intravertebral clefts (IVCs) are vacuum like cavities commonly associated with osteoporotic vertebral compression fractures (OVCFs). IVCs promote cement leakage during kyphoplasty, suggesting a physical link with the basivertebral foramen, although this is uncertain.

Purpose

The present study aims to create IVCs in mechanical experiments on cadaveric spines in order to clarify their pathogenesis, structure, and links with the basivertebral foramen.

Study design and methods

Fifteen three-vertebra lumbar specimens from five cadavers aged 68-71 were subjected to axial compressive overload followed by cyclic loading in flexion and extension to create an OVCF together with an IVC. CT scans and radiographs were used to confirm structural changes and micro-CT was used to measure trabecular bone properties in five specimens. Unipedicular vertebroplasty was then performed on 10 damaged specimens until fluoroscopy revealed extravasation of cement.

Results

In every specimen, loading created an OVCF with an IVC. Dissection and imaging showed that the IVC was always connected with the basivertebral foramen. The central vertebral region, including the IVC, had the lowest connectivity density, trabecular number, and bone volume fraction, and the highest trabecular separation. Vertebroplasty caused cement leakage through the basivertebral foramen in nine specimens and into an adjacent disc in one specimen.

Conclusion

Cyclic loading in flexion and extension applied to a fractured osteoporotic vertebra can create an IVC which then allows cement leakage via the basivertebral foramen.

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