Pathomechanism of intravertebral clefts in osteoporotic compression fractures of the spine: basivertebral foramen collapse might cause intravertebral avascular necrosis

Double Vertebrae Kümmell Disease: Five Cases Report and Literature Review

Kümmell disease (KD) is a complication of osteoporotic vertebral compression fractures. There is a lot of literature on KD, but the reported cases are all single vertebrae. This study reports five double vertebrae KD cases (10 levels) and discusses the possible underlying mechanisms with a literature review. One hundred and thirty vertebrae KD were diagnosed from 2074 osteoporotic vertebral compression fractures patients treated in our hospital between 2015 and 2019. These vertebrae KD were divided into two groups, one-level vertebrae KD (n = 125) and double-level KD (n = 5). The diagnosis of KD is mainly based on the signs of intravertebral vacuum cleft on X-ray or CT scan. Double vertebrae KD cases were classified by using the KD staging system. The analysis was performed on KD to compare age, gender, femoral neck bone mineral density of femoral neck (BMD), vertebrae distribution, Cobb angle, and visual analog scale (VAS) between one-level KD and double-level by t-tests, Welch's t-test, or hypothesis testing. The mean age of the participants in the one-level KD group was 78.69 years, while the mean age in the double-level KD group was 82.4 years. The difference was statistically significant (t = 3.66, p = 0.0004). There were 89 females and 36 males in the one-level KD group, while the double-level KD group had five females and no males. The femoral neck BMD was significantly different between the two groups, with the one-level KD group having a mean BMD of -2.75 and the double-level KD group having a mean BMD of -4.2 (t = 2.99, p= 0.0061). The vertebrae distribution was different between the groups, with the one-level KD group having vertebrae from T7 to L4 and the double-level KD group having vertebrae from T11 to L1. The Cobb angle was also significantly different between the groups, with the one-level KD group having a mean angle of 20.58 and the double-level KD group having a mean angle of 31.54 (t = 6.22, p = 0.0001). Finally, the VAS scores were similar between the two groups, with the one-level KD group having a mean score of 8.63 and the double-level KD group having a mean score of 8.8 (t = 1.35, p = 0.1790). It is concluded that double vertebrae Kümmell disease has special clinical significance due to its potential to cause greater spinal instability and deformity, increased risk of neurological symptoms, more complex surgical management, and greater risk of complications.

Predictors of residual low back pain in patients with osteoporotic vertebral fractures following percutaneous kyphoplasty

Objective

Patients with osteoporotic vertebral fractures (OVFs) often suffer from residual low back pain (LBP) after percutaneous kyphoplasty (PKP). The purpose of this study was to identify risk factors for postoperative residual LBP and to develop a nomogram to predict the occurrence of residual LBP.

Methods

We retrospectively reviewed 236 patients who underwent PKP for OVFs and had a minimum follow-up of 12 months. The mean age was 72.1 ± 6.3, 74.3% were female and 25.7% were male. Patients with LBP VAS scores ≥ 3.5 at the 12th month postoperatively were considered to have residual LBP. Risk factors for residual LBP were identified by univariate and multifactorial logistic regression analysis. Then, a predictive nomogram was constructed and validated using the bootstrap method. The discrimination, calibration, and clinical utility of the nomogram were assessed using a receiver operating characteristic curve (ROC), a calibration curve, and a decision curve analysis (DCA).

Results

univariate and multifactorial logistic regression analysis identified depression (P = 0.02), intravertebral vacuum cleft (P = 0.01), no anti-osteoporosis treatment (P < 0.001), cement volume <3 ml (P = 0.02), and cement distrubution (P = 0.01) as independent risk factors for residual LBP. The area under the ROC was 0.83 (0.74-0.93) and further validated by bootstrap method was 0.83 (0.73-0.92). The calibration curve illustrated the consistency between the predicted probability and the observed results. DCA showed that nomogram exhibits clinical utility and net benefit when the threshold probability is between 6% and 73%.

Conclusions

Our study found that depression, intravertebral vacuum cleft, no anti-osteoporosis treatment, cement volume <3 ml and cement distribution represent independent risk factors for residual LBP. The nomogram containing the above five predictors can accurately predict the risk of residual LBP after surgery.

Morphological features of basivertebral foramen among different age groups: Recognition in spine

Background

Basivertebral foramen (BF) is a vessel and nerve passage in the posterior wall of vertebral body (VB). Our goal was to report BF's morphological characteristics in different age groups of mainland Chinese adults and to evaluate the relationship between BF's morphology and factors such as age, gender, heavy work, size and level of VB.

Methods

We enrolled 300 adults among persons who came to our hospital for health examination. We measured BFs and VBs' parameters on T1 weighted sagittal lumbar spine MR images. We also assessed following potential predictors: gender, body height, body weight, body mass index, alcohol use, habits of smoking and drinking, type of work (physical work or non-physical work). A stepwise multivariate linear regression analysis was conducted to identify predictors of BF's height.

Results

People above 60 have significantly bigger BFHr than those in young adulthood and in the middle ages at all five levels, while they have shallowest BFs, especially at L3. Multiple linear regression resulted in a formula that accounted for 30.1% of the variability in the height of basivertebral foramen. Significant predictors included: gender, age, level, vertebral height and heavy work.

Conclusion

Age is the highest weight in all factors on the height of BF. BF is closer to the upper endplate. The BF was relatively higher and deeper in the female lumbar spine. Heavywork results in lower BF. Last but not the least, as we supposed, BF gets shallower and higher compare to VB with age.

Level of evidence

Prognostic level III. See instructions for authors for a complete description of levels of evidence.

Basivertebral foramina of true vertebrae: morphometry, topography and clinical considerations

PURPOSE

Basivertebral foramina (BVF) are openings of the posterior wall of vertebral body (VB) that lead to basivertebral canals (BVC), where homonymous neurovascular bundle courses. BVF and BVC are implicated with spinal fractures, vertebral augmentation and basivertebral nerve radiofrequency ablation. Despite their essential clinical impact, knowledge of BVF precise anatomy is scarce. The current study describes in detail the BVF typical morphological and topographical anatomy, morphometry and variants.

METHODS

In total, 1561 dried true vertebrae of 70 Greek spines of known gender and age were examined. BVF number, location, shape and size (in foramina > 1 mm), BVF distance from VB rims and pedicles, as well as VB morphometry (diameters, heights and distance between pedicles) were studied. Ten spines were re-examined by computed tomography and BVC depth and shape were recorded. Correlations and differences were statistically analyzed.

RESULTS

C₁ lack BVF (3.4%). One BVF was found in 45.1%, two in 36.9%, three in 3.8% and four BVF in 0.6%. Multiple small (< 1 mm) foramina were observed in 10.1%. Asymmetry was detected in 12.3%. C₂ and T₁₀-L₁ presented typical pattern, whereas C₃ and T₂ had the greatest variability. BVF were significantly closer to the upper rim in C₂ and T₁₀-L₄ and to the lower rim in C₇-T₄, T₆-T₈ and L₅. The mean BVC depth was 12-21.8% of the VB anteroposterior diameter.

CONCLUSION

BVF number, shape, size and topography are described, in detail, per vertebral level. The provided morphological classification and the created cumulative BVF topographic graphs should assist in clinical practice and surgery.

Modified poly(methyl methacrylate) bone cement in the treatment of Kümmell disease

Kümmell disease (KD) causes serious vertebral body collapse in patients. However, only a few case reports have been conducted and the number of patients with KD investigated was limited. Additionally, the frequently used poly(methyl methacrylate) (PMMA) bone cement for KD is limited by excessive modulus and poor biocompatibility. Herein, we aimed to modify PMMA bone cement with mineralized collagen (MC), and compare the clinical effects, image performance and finite element analysis between the modified bone cement and PMMA bone cement for the treatment of phase I and II KD. Thirty-nine KD patients treated with PMMA bone cement and 40 KD patients treated with MC-modified PMMA bone cement from June 2015 to March 2017 were retrospectively analyzed. The surgical procedure, intraoperative blood loss, hospital stay and complications were compared between different groups. Visual analog scale, Oswestry disability index, anterior vertebral height, posterior vertebral height, computed tomography value, adjacent vertebral re-fracture, Cobb angle and wedge-shaped correction angle were evaluated. Additionally, the representative sample was selected for finite element analysis. We found that the MC-modified PMMA bone cement could achieve the same effect as that of PMMA bone cement and was associated with better vertebral height restoration in the long term.

Trabecular Microstructure and Damage Affect Cement Leakage From the Basivertebral Foramen During Vertebral Augmentation

STUDY DESIGN

A prospective study on cadaver specimens.

OBJECTIVE

To explore why cement leakage from basivertebral foramen (BF) easily occurs during vertebral augmentation procedures.

SUMMARY OF BACKGROUND DATA

Type B (through BF, basivertebral foramen) cement leakage is the most common type after vertebral augmentation, but the mechanism of this is still controversial. The contribution of vertebral trabecular bone orientation and trabecular damage during compression fracture to cement leakage is still unknown.

METHODS

In this study, 12 fresh-frozen human lumbar spines (T12-L5) were collected and divided into 24 three-segment units. Mechanical testing was performed to simulate a compression fracture. MicroCT were performed on all segments before and after mechanical testing, and trabecular microstructure of the superior, middle (containing BF), and inferior 1/3 of each vertebral body was analyzed. The diameter variation of intertrabecular space before and after compression fracture was used to quantify trabecular injury. After mechanical testing, vertebral augmentation, and imaging-based diagnosis were used to evaluate cement leakage.

RESULTS

Trabecular bone microstructural parameters in middle region (containing BF) were lower than those of the superior or inferior regions (P < 0.01). After compressive failure, 3D-reconstruction of the vertebral body by MicroCT demonstrated that intertrabecular distance in the middle region was markedly increased. Type B cement leakage was the most common type after vertebral augmentation, as found previously in Wang et al. (Spine J 2014;14: 1551-1558).

CONCLUSION

The presence of the BF and the relative sparsity of trabecular bone make the middle region of the vertebral body the mechanically weakest region. Trabecular bone in middle region suffered the most severe damage during compressive failure of the vertebral body, which resulted in the greatest intervertebral spacing, and subsequently the highest percentage of type B cement leakage. These data suggest specific mechanisms by which cement may leak from the BF, and the contribution of trabecular microstructure and trabecular injury.

LEVEL OF EVIDENCE

4.

New Landmark for Localizing the Site of the Subdental Synchondrosis Remnant: Application to Discerning Pathology from Normal on Imaging

OBJECTIVE

We hypothesized that the entry site of the basivertebral vein into the basivertebral foramen of C2 might localize the subdental synchondrosis between the odontoid process and body of C2, which may be helpful for odontoid fracture classification.

METHODS

Twenty-five dry adult C2 specimens underwent thin-cut computed tomography and were sectioned sagittally. The basivertebral foramen was then correlated to internal bony anatomy. Fifty magnetic resonance images were reviewed, and the location of the subdental synchondrosis was determined.

RESULTS

A basivertebral foramen was identified on the posterior surface of all dry C2 specimens. The openings were found at a distance of 30%-44% on an inferosuperior point along the vertical height of C2. For bony specimens with a subdental synchondrosis remnant (75%), entry of acupuncture needles into the basivertebral foramen was always directly at the level of the synchondrosis remnant. For magnetic resonance imaging (MRI), a subdental synchondrosis or its remnants were seen on all studies. The distance from the base of C2 to the subdental synchondrosis ranged from 9-13 mm. This equated to an inferosuperior point 32%-43% along the vertical height of C2. A strong correlation existed when comparing the location of the basivertebral foramen of bony specimens and the subdental synchondrosis location on MRI.

CONCLUSIONS

The basivertebral foramen is a consistently present anatomic reference point for the subdental synchondrosis even if the latter cannot be seen on conventional radiographic imaging. Our MRI data might also be useful in helping differentiate lesions affecting C2 from normal subdental cartilaginous remnants that can be encountered on imaging.