Female Human Spines with Simulated Osteolytic Defects: CT-based Structural Analysis of Vertebral Body Strength

Abstract

Purpose To evaluate a CT structural analysis protocol (SAP) for estimating the strength of human female cadaveric spines with lytic lesions. Materials and Methods Osteolytic foci was created in the middle vertebra of 44 thoracic and lumbar three-level segments from 11 female cadavers (age range, 50-70 years). The segments underwent CT by using standard clinical protocol and their failure strength was assessed at CT SAP. The spines were mechanically tested to failure in pure axial compression or in compression with torsion. The relationships of defect size, bone mineral density, and predicted failure load (at CT SAP) with measured vertebral strength were assessed with linear regression. Analysis of variance and Tukey test were used to evaluate the effect of region and mechanical test on spine strength. Results With axial compression, CT SAP predictions of vertebral strength correlated with the thoracic (r = 0.84; P < .001) and lumbar (r = 0.85; P < .001) segment-measured strength. Bone mineral density correlated with the lumbar (r = 0.64; P = .003) and thoracic (r, 0.51; P = .050) strength. At compression with torsion, CT SAP predictions of strength were moderately correlated with vertebral strength (r = 0.66; P = .018). At compression with torsion, bone mineral density was not correlated with spinal strength (thoracic and lumbar: r = 0.31 and r = 0.26, respectively; P = .539 and .610, respectively). The lytic focus size (range, 28%-41%) was not associated with vertebral strength. Conclusion CT SAP assessment of strength in vertebrae with lytic lesions correlated with the measured strength of female vertebral bodies. RSNA, 2018 Online supplemental material is available for this article.

Healing pattern classification for thoracolumbar burst fractures after posterior short-segment fixation

“…Cavities or lesions can remain in the healed vertebral bodies, as observed in figures from previously reported studies in the literature [9,[11][12][13]. Given that focal regions of bone loss have been proven to reduce the structural competence of vertebrae, these cavity lesions may be significantly related to the recurrence of vertebral collapse after implant removal [14][15][16]. Furthermore, the impact of a lesion on the structural properties of the vertebral body is related to its size and location [16].…”

Large Lytic Defects Produce Kinematic Instability and Loss of Compressive Strength in Human Spines

“…As part of a previous study 23 , 3-level segments (T6-T8, T9-T11, T12-L2, and L3-L5) were obtained from 8 fresh-frozen cadaver spines from female donors with a mean age (and standard deviation) of 57 ± 6.6 years (range, 47 to 69 years). Each segment underwent CT imaging (Aquilion 64; Canon Medical Systems) to inspect for existing pathology or fractures and compute vertebral bone mineral density 23 . Twenty-four segments were selected for kinematic assessment (n = 6 for each segment), the segments were dissected clean of musculature, and the cranial and caudal vertebrae were shallowly embedded in cement for mechanical testing 23 .…”

Fracture Risk Evaluation of Bone Metastases: A Burning Issue

“…Hence, defect size is not the only predictive factor for vertebral strength reduction. Defect location is also predictive, especially for vertebral segments including the pedicles or costovertebral joints [112,113,[115][116][117]. A previous study also showed that transcortical defects reduce the vertebral strength [116], meaning that defect type is also a factor to be considered.…”

“…The experimental studies investigating the influence of the defect size on the vertebral strength have drawn conflicting results. In some cases, defect size was considered as a predictive factor of vertebral strength [109][110][111], while the opposite has been reported in other studies [112][113][114]. Hence, defect size is not the only predictive factor for vertebral strength reduction.…”

“…In published studies, defects were mostly created by drilling to mimic lytic metastases, which led to bone destruction. However, this technique caused cortical damage [107,110,112,113,[116][117][118][119], which lead to vertebral strength reduction [116]. Another approach is to directly reuse experimental compression protocols developed in osteoporosis contexts in intact vertebral bodies for inducing anterior wedge-shape fracture [120] and test metastatic vertebrae.…”