Development and internal validation of a clinical prediction model for acute adjacent vertebral fracture after vertebral augmentation

Aims To develop and internally validate a preoperative clinical prediction model for acute adjacent vertebral fracture (AVF) after vertebral augmentation to support preoperative decision-making, named the after vertebral augmentation (AVA) score. Methods In this prognostic study, a multicentre, retrospective single-level vertebral augmentation cohort of 377 patients from six Japanese hospitals was used to derive an AVF prediction model. Backward stepwise selection (p < 0.05) was used to select preoperative clinical and imaging predictors for acute AVF after vertebral augmentation for up to one month, from 14 predictors. We assigned a score to each selected variable based on the regression coefficient and developed the AVA scoring system. We evaluated sensitivity and specificity for each cut-off, area under the curve (AUC), and calibration as diagnostic performance. Internal validation was conducted using bootstrapping to correct the optimism. Results Of the 377 patients used for model derivation, 58 (15%) had an acute AVF postoperatively. The following preoperative measures on multivariable analysis were summarized in the five-point AVA score: intravertebral instability (≥ 5 mm), focal kyphosis (≥ 10°), duration of symptoms (≥ 30 days), intravertebral cleft, and previous history of vertebral fracture. Internal validation showed a mean optimism of 0.019 with a corrected AUC of 0.77. A cut-off of ≤ one point was chosen to classify a low risk of AVF, for which only four of 137 patients (3%) had AVF with 92.5% sensitivity and 45.6% specificity. A cut-off of ≥ four points was chosen to classify a high risk of AVF, for which 22 of 38 (58%) had AVF with 41.5% sensitivity and 94.5% specificity. Conclusion In this study, the AVA score was found to be a simple preoperative method for the identification of patients at low and high risk of postoperative acute AVF. This model could be applied to individual patients and could aid in the decision-making before vertebral augmentation. Cite this article: Bone Joint J 2022;104-B(1):97–102.

Impact of Multifidus Muscle Atrophy on the Occurrence of Secondary Symptomatic Adjacent Osteoporotic Vertebral Compression Fractures

To assess the potential influence of multifidus atrophy and fatty degeneration on the incidence of adjacent vertebral compression fractures within one year after the index fracture. In a retrospective cohort study, patients who underwent surgery for an OVCF were identified and baseline characteristics, fracture patterns and the occurrence of secondary adjacent fractures within one year were obtained by chart review. Multifidus muscle atrophy and fatty degeneration were determined on preoperative MRI or CT scans. In this analysis of 191 patients (mean age 77 years, SD 8, 116 female), OF type 3 was the most common type of OVCF (49.2%). Symptomatic adjacent OVCFs within one year after index fracture were observed in 23/191 patients (12%) at mean 12, SD 12 weeks (range 1–42 weeks) postoperatively. The mean multifidus muscle area was 264, SD 53 mm2 in patients with an adjacent vertebral fracture and 271, SD 92 mm2 in patients without a secondary fracture (p = 0.755). Mean multifidus fatty infiltration was graded Goutallier 2.2, SD 0.6 in patients with an adjacent fracture and Goutallier 2.2, SD 0.7 in patients without an adjacent fracture (p = 0.694). Pre-existing medication with corticosteroids was associated with the occurrence of an adjacent fracture (p = 0.006). Multifidus area and multifidus fatty infiltration had no significant effect on the occurrence of adjacent vertebral fractures within one year after the index fracture. Patients with a pre-existing medication with corticosteroids were more likely to sustain an adjacent fracture.

Is Osteoporotic Thoracolumbar Burst Fracture a Contraindication to Percutaneous Kyphoplasty? A Systematic Review

BACKGROUND: The management of pain after osteoporotic thoracolumbar burst fracture has not reached a treatment consensus. Percutaneous kyphoplasty has been shown to be efficient in reducing acute pain after burst fracture, although the topic remains highly controversial in this field. OBJECTIVE: This study aimed to conduct a systematic review of the current literature to evaluate the effectiveness and safety of percutaneous kyphoplasty on the treatment of osteoporotic thoracolumbar burst fracture. STUDY DESIGN: A systematic review. SETTING: University hospital. METHODS: A comprehensive literature search was performed through PubMed, EMBASE, Web of Science, and Cochrane library without time restriction. Among the studies meeting the eligible criteria, any study in which percutaneous kyphoplasty was utilized alone in the treatment of osteoporotic thoracolumbar burst fracture was included in the current review. For radiographic outcome evaluation, vertebral height and kyphotic angle were analyzed. VAS (Visual Analog Scale) and ODI (Oswestry Disability Index) were utilized for clinical outcome evaluation. Complications such as cement leakage and adjacent vertebral fracture or relapse were also analyzed. RESULTS: In total, 289 patients (338 vertebral bodies) were included in the 8 studies. Clinical outcomes indicated that patients achieved pain relief (VAS) from 6.8 preoperatively to 1.1 postoperatively, and improvement of quality of life (ODI) ranged from 87.0 ± 6.0% to 23.9 ± 4.4%. The radiological outcome indicated that anterior vertebral height restoration ranged from 20.1 ± 2.3 to 85.3 ± 10.6, and posterior vertebral height restoration ranged from 27.3 ± 1.7 to 83.3 ± 7.4. Kyphotic angle achieved correction ranged from 21.7 ± 7.8° preoperatively to 3.17° postoperatively. The main complications after PKP were cement leakage and adjacent vertebral fracture or relapse, which had an incidence of 7.7% -45.4% and 4.3% -74.1%, respectively. LIMITATIONS: Due to the good quality of the English publications, only English-language research searches were conducted, but they do not unduly affect our aggregate results impact. More prospective randomized controlled trials are needed to provide higher evidence for clinical practice. CONCLUSIONS: To osteoporotic thoracolumbar burst fracture is absolutely not a contraindication to percutaneous kyphoplasty. Percutaneous kyphoplasty can obtain satisfactory effectiveness for the treatment of osteoporotic thoracolumbar burst fractures. Complications can be effectively decreased by meticulous evaluation, careful manipulation, and appropriate precautionary measures. KEY WORDS: Percutaneous kyphoplasty, osteoporosis, burst fracture, cement leakage, adjacent fracture

Direct Lateral Corpectomy and Reconstruction Using an Expandable Cage Improves Local Kyphosis but Not Global Sagittal Alignment

Recently, an expandable cage equipped with rectangular footplates has been used for anterior vertebral replacement in osteoporotic vertebral fracture (OVF). However, the postoperative changes in global alignment have not been elucidated. The purpose of this study was to evaluate local and global spinal alignment after anterior and posterior spinal fixation (APSF) using an expandable cage in elderly OVF patients. This retrospective multicenter review assessed 54 consecutive patients who underwent APSF for OVF. Clinical outcomes were compared between postoperative sagittal vertical axis (SVA) > 95 mm and ≤95 mm groups to investigate the impact of malalignment. SVA improved by only 18.7 mm (from 111.8 mm to 93.1 mm). VAS score of back pain at final follow-up was significantly higher in patients with SVA > 95 mm than SVA ≤ 95 mm (42.4 vs. 22.6, p = 0.007). Adjacent vertebral fracture after surgery was significantly more frequent in the SVA > 95 mm (37% vs. 11%, p = 0.038). Multiple logistic regression showed significantly increased OR for developing adjacent vertebral fracture (OR = 4.76, 95% CI 1.10–20.58). APSF using the newly developed cage improves local kyphotic angle but not SVA. The main cause for the spinal malalignment after surgery was postoperative development of adjacent vertebral fractures.

A study on the relationship between the rate of vertebral body height loss before balloon kyphoplasty and early adjacent vertebral fracture

BACKGROUND: The number of patients with an osteoporotic vertebral compression fracture, which is often accompanied by lower back pain and restrained activities, is growing. Balloon kyphoplasty involves the inflation of a balloon to restore height and reduce kyphotic deformity before stabilization with polymethylmethacrylate. However, there is a great deal of debate about whether balloon kyphoplasty also increases fracture morbidity by either inducing or facilitating subsequent adjacent vertebral fractures. OBJECTIVE: To evaluate the relationship between the rate of vertebral body height loss before balloon kyphoplasty and the etiology of early adjacent vertebral fracture after augmentation. METHODS: A total of 59 patients with osteoporotic vertebral compression fractures who underwent kyphoplasty were enrolled. This study defined early adjacent segmental fractures as new fractures occurring within three months after surgery. This study included the rate of vertebral body height loss. RESULTS: Early adjacent vertebral fractures were diagnosed in nine (15%) of the 59 patients. The patients were divided into two groups, with and without adjacent vertebral fractures. There was no significant difference in terms of age, body mass index, bone mineral density, local kyphotic angle, Cobb’s angle, cement volume, cement leakage, and percent height restored between the groups with fractures and without fractures. There was a statistically significant difference between the two groups in the rate of vertebral body height loss. The rate of vertebral body height loss was significantly higher in the fracture group than in the without fracture group. CONCLUSIONS: A high rate of vertebral body height loss increased the risk of early adjacent vertebral fractures after balloon kyphoplasty.

Biomechanical Comparison of Vertebral Augmentation and Cement Discoplasty for the Treatment of Symptomatic Schmorl’s Node Combined With Modic Change: Finite Element Analyses

Study design: Finite element simulation study.Objective: To compare the biomechanical effects of percutaneous vertebral augmentation (PVA) and percutaneous cement discoplasty (PCD) in patients with symptomatic Schmorl’s node combined with Modic change.Methods: CT data from a single patient was assembled into finite element models, from which we constructed four distinct surgical models, including PVA-ideal, PVA-nonideal, PCD-ideal, and PCD-nonideal, to compare the stress and strain differences of parapodular tissues.Results: The validity of our model was confirmed. PVA-ideal model showed a moderate reduction in the stress peak of the Schmorl’s node (0.48 vs. 0.81–0.89 Mpa) in the erect position. In the PCD-ideal model, the stress peak of the Schmorl’s node increased significantly when the spine was moved toward the lesion (3.99Mpa). Both PVA-ideal and PCD-ideal models showed global strain inhibition at the Schmorl’s node and BMEZ, which was attenuated in the non-ideal models. The PCD-ideal model significantly reduced segmental ROM (-76.8% to -59.3%) and significantly increases endplate stress (up to 220.8%), with no such effects seen in the PVA-ideal model.Conclusions: Both PVA-ideal and PCD-ideal models facilitated a more stable parapodular biomechanical microenvironment. The PVA-ideal model yielded minimal stress disturbance on the augmented or adjacent vertebral endplate but offered no improvement to segment stability. The PCD-ideal model provides adequate segment stability, but also carries a greater risk for adjacent vertebral fracture. As nonideal implementations of both surgeries can result in poor biomechanical outcomes, the surgical indications of PVA or PCD need to be carefully selected.

What Are the Risk Factors for Adjacent Vertebral Fracture After Vertebral Augmentation? A Meta-Analysis of Published Studies

Study Design: Meta-analysis. Objectives: To provide up-to-date evidence-based outcomes for the incidence and risk factors of adjacent vertebral fracture (AVF) after the vertebral augmentation. Methods: The MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched for studies assessing the risk factors of adjacent vertebral fracture after vertebral augmentation until June 2020. The AVF incidence and factors potentially affecting AVF were extracted and pooled. Results: A total of 16 studies, encompassing 2549 patients were included in the meta-analysis. The pooled incidence of AVF was 14% after vertebral augmentation. Female, lower T-score, thoracolumbar junction fracture, intravertebral cleft, more injected cement volume, intradiscal cement leakage significantly increased the risk of AVF. Age, body mass index, steroid medication, Cobb angle change, postoperative Cobb angle showed no significant association with AVF. Conclusions: Identifying the risk factors of AVF can facilitate prevention strategy to avoid the AVF. Female, T-score, thoracolumbar junction fracture, intravertebral cleft, more cement volume, and intradiscal cement leakage increased the risk of AVF.

A Study of Risk Factors for Early-Onset Adjacent Vertebral Fractures After Kyphoplasty

Study Design: Retrospective study. Objectives: To elucidate risk factors for early-onset (2 months after initial kyphoplasty) adjacent vertebral fracture (EO-AVF) after kyphoplasty. Methods: A total of 108 vertebral bodies (95 patients) were included in this study. We examined patient backgrounds, the spinal level of EO-AVFs, surgery-related factors, and imaging findings. We divided the cases into 2 groups: patients with EO-AVF and patients without EO-AVF. Univariate, correlation, and multivariate analyses were conducted to reveal the risks factors for EO-AVFs for these 2 groups. Results: EO-AVFs developed in 28 vertebral bodies; they did not develop in 80 vertebral bodies. The overall EO-AVF incidence rate was 26%. The spinal level was the thoracolumbar junction for 93% of patients and another level for 7%, thus demonstrating the concentration of EO-AVFs in the thoracolumbar junction. For patients without EO-AVF and those with EO-AVF, there were significant differences in age (76 and 80 years, respectively), preoperative vertebral angles (VAs) (17.8° and 23°, respectively), and corrected VAs (7.3° and 12.7°, respectively). Significant differences were not observed for other factors. Pearson’s correlation coefficient was 0.661 ( P < .000), thereby showing a significantly positive correlation between preoperative VAs and corrected VAs. Logistic regression analysis indicated that age (odds ratio, 1.112; 95% CI, 1.025-1.206) and preoperative VAs (odds ratio, 1.08; 95% CI, 1.026-1.135) were covariates and that the presence of an EO-AVF was a dependent variable. Therefore, both were predictable risk factors for EO-AVFs. Conclusion: Age, preoperative VAs, and corrected VAs are risk factors for EO-AVFs after kyphoplasty.