The biomechanics of vertebroplasty. The effect of cement volume on mechanical behavior

[Translated article] Truths and myths about augmentation techniques in the treatment of fragility fractures

The main event of osteoporosis is fragility fractures. Vertebral compression fractures are the most commonly fragility fracture related to osteoporosis. Our goal is to review the available literature to confirm or deny concepts learned about spinal cementation and adapt our clinical practice according to scientific evidence. In the complex world of spine surgery, constant innovations seek to improve the quality of life of patients. Among these, vertebral augmentation has emerged as an increasingly popular technique, but often shrouded in myths and misunderstandings. In this systematic review, we will thoroughly explore the truths behind vertebral augmentation, unravelling common myths and providing a clear insight into this technique. As specialists in the field, it is crucial to understand the reality surrounding these interventions to offer our patients the best possible information and make informed decisions.

Comparison of the efficacy and safety of vertebroplasty with different pedicle approaches for osteoporotic vertebral

OBJECTIVE

To compare the efficacy and safety of vertebroplasty through different pedicle approaches in the treatment of osteoporotic vertebral compression fracture osteoporotic vertebral compression fractures (OVCF) by network meta-analysis.

METHODS

Pubmed, Embase, Cochrane Library, Web of Science. Database for literature retrieval, retrieval time from the establishment of the database to April 2023, the randomized controlled trials of unilateral vertebroplasty (UVP), bilateral vertebroplasty (BVP), unilateral kyphoplasty (UKP), bilateral kyphoplasty (BKP), curved vertebroplasty (CVP) and curved kyphoplasty (CKP) were screened, evaluated and the data were extracted and included in the analysis. STATA 15.0 and ReMan 5.3 were used for data analysis. This study was registered in the National Institute for Health Research (NIHR) with the registration number CRD42023405181.

RESULTS

This study included 16 articles with a total of 1712 patients. The order of visual analogue scale (VAS) improvement from good to bad is CVP > BVP > UVP > CKP > BKP > UKP. The order of kyphotic angles improvement from good to bad is CKP > UKP > UKP > UVP > BVP > CVP. The order of bone cement injection from less to more is UVP > CVP > UKP > CKP > BVP > BKP. The order of bone cement leakage rate from less to more is CKP > CVP > UKP > BKP > UVP > BVP. The order of X-ray exposure time from less to more is CKP > CVP > UVP > BVP > UKP > BKP. The order of operation time from less to more is CVP > UVP > UKP > CKP > BVP > BKP.

CONCLUSION

For patients with kyphotic angles, kyphoplasty has unique advantages in improving kyphotic angles. But generally speaking, curved approach can optimize the distribution of bone cement through unilateral approach to achieve the orthopedic effect of bilateral approach, which is a minimally invasive technique with better curative effect and higher safety in the treatment of OVCF.

Effect of cement volume on biomechanical response of a spine segment treated with a PEEK polymer implant: a finite element comparative study with vertebroplasty

In the current study, a 3D finite element study was performed to investigate the biomechanical response of an osteoporotic spine segment treated with a novel transpedicular implant (V-STRUT©, Hyprevention, France) made of PEEK (polyetheretherketone) material combined with either injections of 2, 3, 4, 5 and 6 cc of cement. The objective was to assess numerically the biomechanical performance of the implant in combination with different doses of the injected bone cement and to compare its performance with the gold standard vertebroplasty (VP) technique. A female (69 yo) was selected and a 3D finite element model of an osteoporotic spine segment was built based on a Computed Tomography (CT) scan performed from T12 to L2 with corresponding intervertebral discs and ligaments. A heterogeneous distribution of bone material properties was assigned to the bone using grey scale levels. Bilateral ellipsoid geometries of the inserted cement were retained for the V-STRUT and VP models based on experimental observation performed on different patients treated with the V-STRUT device. The current study demonstrated an optimal dose of 4 cc of bilaterally injected cement for the V-STRUT and VP techniques to restore the treated segment and confirmed that the V-STRUT device in combination with bone cement is superior to VP alone in establishing the normal stiffness and in reducing the applied stress to the immediately adjacent vertebral levels.

Truths and myths about augmentation techniques in the treatment of fragility fractures

The main event of osteoporosis is fragility fractures. Vertebral compression fractures are the most commonly fragility fracture related to osteoporosis. Our goal is to review the available literature to confirm or deny concepts learned about spinal cementation and adapt our clinical practice according to scientific evidence. In the complex world of spine surgery, constant innovations seek to improve the quality of life of patients. Among these, vertebral augmentation has emerged as an increasingly popular technique, but often shrouded in myths and misunderstandings. In this systematic review, we will thoroughly explore the truths behind vertebral augmentation, unraveling common myths and providing a clear insight into this technique. As specialists in the field, it is crucial to understand the reality surrounding these interventions to offer our patients the best possible information and make informed decisions.

Percutaneous Curved Vertebroplasty Decrease the Risk of Cemented Vertebra Refracture Compared with Bilateral Percutaneous Kyphoplasty in the Treatment of Osteoporotic Vertebral Compression Fractures

Purpose

The purpose of this study is to compare the refracture rate of the cemented vertebral body of percutaneous curved vertebroplasty (PCVP) and bilateral percutaneous kyphoplasty (PKP) in the treatment of osteoporotic vertebral compression fractures (OVCF).

Methods

Ninety-four patients with single segment thoracolumbar OVCF were randomly divided into two groups (47 patients in each) and underwent PCVP or bilateral PKP surgery, respectively. Refracture of cemented vertebral body, bone cement injection volume and cement pattern, cement leakage rate, total surgical time, intraoperative fluoroscopy time, preoperative and postoperative Cobb angles and anterior vertebral height, Oswestry disability index questionnaire (ODI) and visual analog scales (VAS) were recorded.

Results

The PCVP group had significantly lower refracture incidence of the cemented vertebral than the bilateral PKP group (p<0.05). There was a significant postoperative improvement in the VAS score and ODI in both group (p<0.01), and no significant difference was found between two groups. The operation time and intraoperative fluoroscopy times were significantly less in the PCVP group than in the bilateral PKP group (p<0.01). The mean kyphosis angle correction and vertebral height restoration in the PCVP group was significantly less than that in the bilateral PKP group (p<0.01).

Conclusion

Both PCVP and PKP were safe and effective treatments for OVCF. The PCVP had lower refracture rate of the cemented vertebral than the bilateral PKP group, and PCVP entailed less exposure to fluoroscopy and shorter operation time than bilateral PKP.

Percutaneous lordoplasty for the treatment of severe osteoporotic vertebral compression fractures with kyphosis

Objective

The study aimed to explore the safety and effectiveness of percutaneous lordoplasty (PLP) in the treatment of severe osteoporotic vertebral compression fracture (OVCF).

Methods

Included in this prospective study were patients with single-segment acute severe OVCF who were treated with PLP in our institution from July 2016 to October 2019. Patients' back pain and quality of life were assessed using the visual analog scale (VAS) and SF-36 scores. Lateral X-ray radiography of the spine was performed to measure the vertebral height, vertebral kyphotic angle, and segmental kyphotic angle, and to evaluate the outcome of fracture reduction and kyphotic correction. Intra-and postoperative complications were recorded.

Results

Of the 51 included patients, 47 patients were followed up for 12 months. The VAS score decreased from preoperative 7.33 ± 1.92 to postoperative 1.76 ± 0.85 at the 12th month (p < 0.05), and the SF-36 score increased from preoperative 79.50 ± 9.22 to postoperative 136.94 ± 6.39 at the 12th month (p < 0.05). During the 1-year follow-up period, the anterior height of the vertebral body increased significantly from preoperative 10.49 ± 1.93 mm to 19.33 ± 1.86 mm (p < 0.05); the posterior height of the vertebral body increased insignificantly from preoperative 22.23 ± 2.36 mm to 23.05 ± 1.86 mm (p > 0.05); the vertebral kyphotic angle decreased significantly from preoperative 18.33° ± 11.49° to 8.73° ± 1.21° (p < 0.05); and the segmental kyphotic angle decreased significantly from preoperative 24.48° ± 4.64° to 11.70° ± 1.34° (p < 0.05). During the 1-year follow-up period, there was no significant difference in the radiologic parameters, VAS scores, and SF-36 scores, between the 1st day and the 12th month of post-operation (P > 0.05). No nerve damage occurred in any of the cases. Intraoperative cement leakage occurred in six cases, and the fracture of the adjacent vertebral body occurred in one case.

Conclusion

PLP can well reduce the risk of fracture and achieve good kyphotic correction and may prove to be a safe, cost-effective and minimally invasive alternative option for the treatment of severe OVCF with kyphotic deformity.

Clinical outcomes with second injection after insufficient bone cement distribution in unilateral kyphoplasty for osteoporotic vertebral compressive fracture: a cohort retrospective study

BACKGROUND

Bone cement distribution is an important factor affecting pain relief and long-term prognosis of osteoporotic vertebral compression fracture (OVCF) treated with vertebral augmentation. Unilateral percutaneous kyphoplasty (PKP) is the most common procedure, and insufficient bone cement distribution is more common than bilateral PKP. However, effective remedies are remain lack. In this study, sufficient cement distribution was achieved by adjusting the working channel followed by second cement injection as a remedy in cases with insufficient cement distribution, and the purpose was to evaluate the clinical outcomes by a retrospective cohort study.

METHODS

From July 1, 2017 to July 31, 2020, OVCF patients treated with unilateral PKP were included in this retrospective cohort study. According to the bone cement distribution (insufficient cement distribution was confirmed when the cement did not exceed the mid line of the vertebral body in frontal film or/and the cement did not contact the upper/lower vertebral endplates in the lateral film.) and whether second injection was performed during surgery, the patients were divided into three groups. Insufficient group: patients with insufficient cement distribution confirmed by fluoroscopy or postoperative x-ray. Second injection group: patients with insufficient cement distribution was found during the procedure, and second injection was performed to improve the cement distribution.

CONTROL GROUP

patients with sufficient cement distribution in one injection. The Primary outcome was cemented vertebrae re-collapse rate. The secondary outcomes included operative time, radiation exposure, cement leakage rate, VAS, ODI, and adjacent vertebral fracture rate.

RESULTS

There are 34 cases in insufficient group, 45 cases in second injection group, and 241 cases in control group. There was no significant difference in baseline data and follow-up time among the three groups.

PRIMARY OUTCOME

The injured vertebrae re-collapse rate of insufficient group was significantly higher than that of second injection group (42.22% vs 20.59%, P = 0.000) and control group (42.22% vs. 18.26%, P = 0.000). Kaplan-Meier survival analysis showed that there was no significant difference in the survival time between second injection group and control group (P = 0.741, Log-rank test), both of which were significant less than that in insufficient group (P = 0.032 and 0.000, respectively).

SECONDARY OUTCOMES

There was no significant difference in VAS score and ODI after operation between second injection group and control group, both of which were superior to those in insufficient group (P = 0.000). At the final follow-up, there was no significant difference in VAS and ODI among the three groups (P > 0.05). The operation time of second injection group was significantly higher than that of insufficient group (53.41 ± 8.85 vs 44.18 ± 7.41, P = 0.000) and control group (53.41 ± 8.85 vs 44.28 ± 7.22, P = 0.000). The radiation exposure of the second injection group was significantly higher than that of insufficient group (40.09 ± 8.39 vs 30.38 ± 6.87, P = 0.000) and control group (40.09 ± 8.39 vs 31.31 ± 6.49, P = 0.000). The cement leakage rate of second injection group (20.59%) was comparable with that of insufficient group (24.44%) and control group (21.26%) (P = 0.877). The length of hospital stay of the second injection group (4.38 ± 1.72) was comparable with that of insufficient group (4.18 ± 1.60) and control group (4.52 ± 1.46) (P = 0.431).

CONCLUSIONS

When cement distribution is insufficient during unilateral PKP, second injection may relieve early pain, reduce the incidence of cemented vertebral re-collapse and adjacent vertebral fracture, without increasing the cement leakage rate, although this procedure may increase the operation time and radiation exposure.

Thoracolumbar Osteoporotic Vertebral Compression Fracture Treatment by Unilateral Percutaneous Vertebroplasty Using Curved Diffusion Needle

Objective

To investigate the clinical effect of unilateral puncture vertebroplasty with curved diffusion needle (CDN) in the treatment of thoracolumbar osteoporotic vertebral compression fracture (OVCFs).

Methods

We used the method of a retrospective study. The clinical data of 38 patients with OVCFs treated by unilateral puncture vertebroplasty with curved diffusion needle from January 2021 to January 2022 were analyzed. The operation time and the amount of bone cement injected were recorded to observe the leakage and dispersion of bone cement during the operation and the incidence of vertebral re-fracture at the last follow-up. Visual analog scale (VAS) and Oswestry disability index (ODI) were used to evaluate the pain and functional improvement before and after surgery.

Results

All patients successfully completed the operation. The operation time was 31.2 ± 5.1 min, and the bone cement injection volume was 4.8 ± 1.1 ml. During the operation, three patients had bone cement leakage, and the leakage rate was 7.8%. The bone cement dispersion was excellent in 31 cases, among which seven cases were good; the postoperative follow-up time was 3-10 months, with an average of 6.3 months; no vertebral body re-fracture occurred. VAS score and ODI at 1d after the operation and at the last follow-up were significantly improved compared with those before the operation, and the difference was statistically significant (P < 0.05). Also there was a significant difference between the postoperative 1d and the last follow-up (P < 0.05).

Conclusions

Unilateral puncture vertebroplasty for the treatment of thoracolumbar OVCFs can obtain good bone cement distribution, safety and does not increase complications, and the clinical effect is satisfactory.

[Translated article] Relation between the volume of injected cement and the vertebral volume in the clinical outcome and in the appearance of leakage after a percutaneous vertebroplasty

OBJECTIVES

To assess the connection between the volume of injected cement and the vertebral volume measured through a volumetric analysis with a computed tomography (CT scan) in relation to the clinical result and the appearance of a leakage in patients who underwent a percutaneous vertebroplasty after an osteoporotic fracture.

MATERIALS AND METHODS

A prospective study of 27 patients (18 female-9 male) with an average age of 69 years old (50-81), and with a one-year follow-up. The study group presented 41 vertebrae with osteoporotic fractures that were treated with a percutaneous vertebroplasty with a bilateral transpedicular approach. The volume of injected cement was registered in each procedure and it was assessed together with the spinal volume measured through a volumetric analysis with CT scans. The percentage of the spinal filler was calculated. The appearance of cement leakage was proved by means of a simple radiography and a postoperative CT scan in all the cases. The leaks were classified according to the location in relation to the vertebral body (posterior, lateral, anterior and in the disc), and the significance (minor: smaller than the largest diameter of the pedicle; moderate: larger than the pedicle but smaller than the height of the vertebra; major: larger than the height of the vertebra).

RESULTS

The average vertebra volume was 26.1cm3, the average volume of the injected cement was 2.0cm3 and the percentage of the average filler was 9%. A total of 15 leaks in 41 vertebrae appeared (37%). The leaks were posterior in 2 vertebrae, vascular in 8 and into the disc in 5 vertebrae. They were deemed as minor in 12 cases, moderate in 1 and major in 2 cases. The preoperative assessment of the pain was as it follows: VAS (8) and Oswestry (67%). The cessation of pain was immediate after a year with the following postoperative results: VAS (1.7) and Oswestry (19%). The only complication was the temporary neuritis with a spontaneous resolution.

CONCLUSIONS

The injection of small amounts of cement, lower than the ones referred to by literary sources, obtains clinical results similar to the ones obtained by injecting higher amounts and it reduces the number of cement leaks and further complications.

Comparative evaluation of an innovative deflectable percutaneous kyphoplasty versus conventional bilateral percutaneous kyphoplasty for osteoporotic vertebral compression fractures: a prospective, randomized and controlled trial

BACKGROUND CONTEXT

Osteoporotic vertebral compression fractures (OVCFs) can be treated with percutaneous kyphoplasty (PKP). In contrast to conventional PKP, the novel deflectable percutaneous kyphoplasty (DPKP), is a unilateral transpedicular approach procedure allowing a similar bilateral puncture effect, which owes to the deflectable curved bone expander creating a transcentral line cavity to achieve uniform distribution of cement and biomechanical balance while reducing operative time and radiation exposure.

PURPOSE

The purpose of this study was to prospectively compare and evaluate an innovative surgical procedure, DPKP, versus conventional bilateral percutaneous kyphoplasty (BPKP).

STUDY DESIGN

This is a prospective randomized controlled trial (RCT).

SAMPLE

The totality of the participants (n=90) suffering from OVCFs between May 2019 and October 2020, were randomized by SAS 9.3 to generate a block randomization sequence, which was utilized to randomize the groups in a 1:1 ratio, assigned to the DPKP group (n=45) and the BPKP group (n=45) to undergo accordingly procedures.

OUTCOME MEASURES

The primary outcome was the total operative time. The secondary outcomes included: comparative assessment of visual analog scale (VAS) scores, Oswestry disability index (ODI), kyphosis angle (KA), anterior border height (AH) of the injured vertebra, frequency of intraoperative X-ray fluoroscopy, the injection volume, distribution pattern and leakage rate of bone cement.

METHODS

All subjects underwent assessment by at least one senior orthopedist and radiologist for the VAS scores, ODI, KA, AH of the injured vertebra, total operative time, the injection volume, distribution pattern, leakage rate of bone cement at preoperative and 24 hours, 6 months, and 1 year postoperatively. Inclusion criteria for subjects in this prospective study were as follows: (1) 60 < age < 80 years old; (2) preoperative spinal X-ray, CT, and MRI confirmed as single-segment, fresh thoracolumbar OVCFs (T5-L5, 15% < collapse < 80%); MRI shows low signal on T1-WI and high signal on T2-WI, especially with STIR high signal characterized by vertebral edema; (3) painful OVCFs refractory to medical treatment, 2 weeks < Symptom duration < 3 months;(4) With significant physical signs of local tenderness; (5) T score of bone mineral density (BMD) < -2.5.

RESULTS

The total operative time was significantly reduced in the DPKP group (43.3±19.58 minutes, 95% CI: 37.23-49.37) compared to the BPKP group (55.16±11.56 minutes, 95% CI: 51.78-58.54) (p<.001). Compared to the BPKP group (frequency of intraoperative X-ray fluoroscopy: 43.42±8.64, 95% CI: 40.90-45.95; the volume of bone cement injected: 5.56±0.85 mL, 95% CI: 5.31-5.81), the frequency of intraoperative X-ray fluoroscopy (30.05±17.41, 95% CI: 24.66-35.45) and volume of bone cement injected (5.08±0.97 mL, 95% CI: 4.78-5.38) significantly reduced in the DPKP group compared to the (p<.001). In addition, compared to the preoperative period, both groups showed significant improvements in the postoperative VAS scores, ODI, KA, and AH (p<.001), but there was no statistical difference between the DPKP and BPKP groups (p>.05) at any time-point. Interestingly, although without statistical differences, a tendency towards a lower rate of bone cement leakage was observed in the DPKP group.

CONCLUSION

Our study results indicate that the innovative DPKP is as safe and effective as BPKP in relieving pain, improving the patient's quality of life, and reconstructing vertebral body height. Particularly, DPKP did reduce operative time and radiation exposure compared to BPKP, which correlated with unilateral and bilateral exposure procedures. Moreover, the final cement distribution was less predictable in DPKP, and further studies are warranted to clarify the advantages of DPKP versus conventional unilateral percutaneous kyphoplasty (UPKP) and BPKP.

Early cement augmentation may be a good treatment option for pain relief for osteoporotic compression fractures: a systematic review and meta-analysis

PURPOSE

The incidence of osteoporotic compression fractures (VCFs) have been rising over the past decades. Presently, vertebral cement augmentation procedures such as balloon kyphoplasty and vertebroplasty are common treatments allowing pain relief and functional recovery. However, there is controversy on whether different timeframes for cement augmentation affects clinical outcomes. Hence, this study aimed to compare pain relief and complication rates between early versus late cement augmentation.

METHODS

A comprehensive systematic review of PubMed, EMBASE, Scopus and Cochrane Library was conducted, identifying studies that compared early versus late cement augmentation for VCFs. As the definitions of "early" and "late" phases across studies are heterogenous, we established the cut-off between early and late phase as intervals to accommodate as many studies as possible for analysis. We conducted two separate analyses with different cut-off intervals and included studies that reported interventions within these respective time intervals. In analysis 1, we included studies which grouped patients into "early" and "late" group based on a cut-off time frame of 2-4 weeks. On the other hand, in analysis 2, we included studies which grouped patients into "early" and "late" groups based on a cut-off time frame of 6-8 weeks. Meta-analysis was conducted via random-effect models, comparing outcomes of interest between early and late groups.

RESULTS

Eleven studies were included. The total cohort size was 712 and 775 patients in analysis 1 and 2 respectively. Mean follow-up was 12.9 ± 3.7 months and 11 ± 0.6 months respectively. VAS change at final follow-up was significantly greater in the early group for both analyses. (MD = - 0.66, p = 0.01; and MD = - 1.18, p < 0.005 respectively). There was no significant difference in post-operative absolute VAS score, number of cement leakage, number of adjacent compression fractures and local kyphotic angle, for both analyses. Patients in both groups experienced reductions in VAS score that exceeded the minimum clinically important difference.

CONCLUSION

Both early and late timeframes for cement augmentation offered significant improvement in pain relief, with similar post-operative absolute pain score, kyphotic angle, cement leakage and adjacent vertebral fractures. Early surgery may offer substantial pain relief in patients presenting with pain as early as < 2-4 weeks of VCFs.

Analysis of the Curative Effect of Curved Angle Vertebroplasty in the Treatment of Osteoporotic Vertebral Compression Fracture

Objective

To evaluate the clinical efficacy of Percutaneous curved vertebroplasty (PCVP) for osteoporotic vertebral compression fracture of the thoracolumbar spine.

Methods

Retrospective analysis of 113 patients with osteoporotic vertebral compressive fractures (OVCFs) in our hospital from January 2017 to January 2020, a total of 120 diseased vertebrae, were divided into PCVP group (35 cases, 37 sections) and bilateral PVP(BVP) group (78 cases, 83 sections). To compare the distribution of baseline clinical data, pain relief (Visual Analog Scale, VAS), ODI (Oswestry Dability Index, ODI), operation time, intraoperative fluoroscopy, postoperative vertebral body re-fracture, and comparison of bone, and to compare the volume of cement penetration and the leakage rate of bone cement, etc.

Results

There was no significant difference in VAS and ODI before operation between the two groups (P > 0.05), and the VAS score and ODI after operation were significantly improved (P < 0.001). Compared with the bilateral PVP group, the operation time, the number of fluoroscopy, and the leakage rate of each layer of bone cement in the PCVP group were significantly reduced (P < 0.05); however, the amount of cement used in the two groups was similar (P > 0.05). There were no serious complications in both groups. In the bilateral PVP group, a total of seven patients had adjacent vertebral fractures or re-fractures of the original vertebral body. However, no patients in the PCVP group had re-fractures in any vertebral body segment.

Conclusion

Both PCVP and bilateral PVP are safe and effective methods for the treatment of osteoporotic vertebral compression fractures, but PCVP has a short operation time, fewer fluoroscopy times, and a low bone cement leakage rate.

Vertebral Augmentation for Painful Type 4 Osteoporotic Compression Fractures: A Comparative Study

BACKGROUND

Type 4 osteoporotic fracture (OF4), according to the classification system of the Spine Section of the German Society for Orthopaedics and Trauma (DGOU), is unstable and requires fixation as per the guidelines of the same group. We evaluated the use of stand-alone vertebral body augmentation (VBA) in pain control of OF4.

METHODS

This is a single-centre, in two hospitals, comparative study to evaluate the effectiveness of percutaneous vertebroplasty (PVP) and kyphoplasty (KP) in pain control of OF4. OF4 patients treated with VBA were compared to a conservatively treated control group. The two groups of OF4 were then compared to similar cohort of OF2 and OF3 patients who were treated by either VBA or expectantly.

RESULTS

A total of 78 cases were studied. VBA of OF4 showed a statistically significant better pain control than conservative treatment. The response of this group of fractures to VBA was similar to that of OF2 and 3.

CONCLUSION

VBA can provide satisfactory pain control for OF4 patients.

A novel classification of cement distribution patterns based on plain radiographs associated with cement filling rate and relevance to the clinical results of unipedicle vertebroplasty

INTRODUCTION

Cement distribution pattern following unipedicle percutaneous vertebroplasty (UVP) for osteoporotic vertebral compression fractures (OVCFs) has been reported in association with clinical results. The present retrospective study aimed to classify the bone cement distribution types following UVP and investigate the differences in clinical efficacy and related complications.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of the patients with single-segment OVCFs who underwent UVP. Cement distribution patterns were divided into the diffuse, block, double band, and single band types according to the plain radiographs and further by cement filling rate (CFR) based on a three-dimension reconstruction of post-operative CT. The cutoff values of CFR were > 34% for the diffuse, block between 34 and 20%, and each band of the double or single band < 20%. Clinical efficacy and related complications were compared among the four cement distribution types 24 h after the operation and the last follow-up.

RESULTS

A total of 155 patients with an average follow-up time of 20.3 months were included. The diffuse type included 26 patients; block, 87; double band, 18; and single band, 24. The VAS and ODI after operation improved significantly in all four groups. The diffuse and block types had similar clinical results. The clinical outcomes in the single band group were the poorest at the last follow-up. The patients with single band type also had the highest rates of body re-collapse and revision surgery for the index level.

CONCLUSION

Diffuse and block groups can better maintain the height of the vertebral body and reduce the risk of vertebral body recompression. The single band has the poorest results, and intraoperative immediate contralateral vertebroplasty was highly recommended.

Percutaneous Sacroplasty for Symptomatic Sacral Pedicle Screw Loosening

Background

This study aimed to evaluate the efficacy of fluoroscopy-guided percutaneous sacroplasty in patients with sacral pedicle screws loosening after instrumented spinal fusion.

Methods

We retrospectively reviewed the medical records of 18 patients who underwent percutaneous sacroplasty to treat sacral pedicle screws loosening from January 2016 to December 2019. Imaging studies, visual analog scale (VAS), length of hospital stay, and complications were recorded. The clinical outcomes based on the Oswestry disability index (ODI) and the modified Brodsky's criteria (MBC) were also evaluated to determine the efficacy of percutaneous sacroplasty.

Results

All patients had undergone at least 1 year of follow-up in our institute (range, 12-24 months). The average VAS score was 5.6 (range, 4-7) before surgery and decreased to 1.7 (range, 1-3) at the final visit. All patients were discharged on the next day after surgery. No patients experienced complications, such as cement leakage, deep infection, or neurologic deterioration. All patients achieved good or excellent outcomes based on the MBC. The ODI scores improved from 51.8 preoperatively to 25.6 postoperatively.

Conclusion

Percutaneous sacroplasty was an effective treatment approach for relieving the patient's symptoms caused by sacral pedicle screws loosening and could be a valuable treatment alternative to extensive revision surgery.

Level of clinical evidence

IV.

Correlation analysis of larger side bone cement volume/vertebral body volume ratio with adjacent vertebral compression fractures during vertebroplasty

OBJECTIVE

To investigate the correlation analysis of larger side bone cement volume/vertebral body volume ratio (LSBCV/VBV%) with adjacent vertebral compression fracture (AVCF) in percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fracture (OVCF).

METHODS

A retrospective analysis of 245 OVCF patients who underwent PVP treatment from February 2017 to February 2021, including 85 males and 160 females. The age ranged from 60 to 92 years, with a mean of (70.72 ± 7.03) years. According to whether AVCF occurred after surgery, they were divided into 38 cases in the AVCF group (fracture group) and 207 cases in the no AVCF group (non-fracture group). The correlation between gender, age, bone mineral density (BMD), body mass index (BMI), thoracolumbar segment fracture, bone cement disc leakage, LSBCV, bone cement volume (BCV), VBV, LSBCV/VBV ratio (LSBCV/VBV%), and BCV/VBV% and AVCF were analyzed in both groups. Risk factors for AVCF after PVP were analyzed by multifactorial logistic regression, and then the receiver operating characteristic curves (ROC curves) were plotted to identify the critical value of LSBCV/VBV%.

RESULTS

38 patients (15.5%) developed AVCF postoperatively. Univariate analysis showed that BMD, bone cement disc leakage, LSBCV, and LSBCV/VBV% were risk factors for AVCF after PVP (P<0.05), while gender, age, BMI, thoracolumbar segment fracture, BCV, VBV, and BCV/VBV% were not significantly different in both groups (P>0.05). Multifactorial logistic regression analysis revealed that BMD, bone cement disc leakage, and LSBCV/VBV% were independent risk factors for AVCF after PVP (P<0.05). According to the ROC curve, the LSBCV/VBV% had an area under the curve of 71.6%, a sensitivity and specificity of 89.5% and 51.7%, respectively, and a critical value of 13.82%.

CONCLUSION

BMD, bone cement disc leakage and LSBCV/VBV% are independent risk factors for AVCF after PVP. With LSBCV/VBV at 13.82%, the incidence of AVCF significantly increased.

Understanding the choice of control group: A systematic review of vertebroplasty trials for osteoporotic vertebral compression fractures

OBJECTIVES

To better understand the choice of the comparator intervention in the design of clinical trials and its impact on the meaning of results we review randomized trials on vertebroplasty.

METHODS

We conducted a systematic and narrative review of all randomized trials on vertebroplasty. Trials are categorized according to the comparator intervention (non-surgical management, placebo/sham vertebroplasty, and kyphoplasty).

RESULTS

All trials were too small to show a difference in objective clinical outcomes, and 20 of 23 RCTs used mean pain scores to compare interventions. Most trials comparing vertebroplasty with non-surgical management concluded that vertebroplasty was superior. Trials comparing kyphoplasty with vertebroplasty showed similar results for both interventions. However, 4 of 5 trials comparing vertebroplasty with placebo surgery failed to show a significant difference between groups.

CONCLUSION

The clinical results of an intervention cannot be interpreted without a comparison that involves a control group. The choice of comparator intervention can change the meaning of the trial. A large pragmatic trial, using hard clinical outcomes such as morbidity and mortality as a primary outcome measure, would be needed to assess the potential clinical benefits of vertebroplasty.

Risk factors for new vertebral compression fracture after kyphoplasty and efficacy of osteoporosis treatment: A STROBE-compliant retrospective study

Kyphoplasty (KP) has been widely used to treat vertebral compression fractures (VCFs). However, the issue of new VCFs after KP remains controversial. Identification of risk factors for new VCF after KP may help prevent their occurrence in patients. This study aimed to retrospectively determine the major risk factors for new VCF after KP, including those associated with osteoporosis drugs used after kyphoplasty. We reviewed 117 patients who underwent single-level KP. During the follow-up period of 1 year after KP, the demographic data of these patients were compared by dividing them into two groups: those with new fractures (n = 19) and those without new fractures (n = 98). We investigated the age, sex, fracture location, medical history, steroid use history, bone mineral density (BMD), type of osteoporosis treatment, period from fracture to KP, KP method (unilateral or bilateral), bone cement dose, intradiscal cement leakage, preoperative and postoperative compression ratio, kyphotic angle (KA), and lowest vertebral body height in the fractured vertebrae. Based on these data, the factors related to new VCFs after KP were investigated using univariate and multivariate logistic regression analyses. We also investigated whether there were differences in new VCFs according to the type of osteoporosis treatment. During the 1-year follow-up period after KP, the rate of new VCFs was 16.2%. Factors related to new VCFs were BMD, intradiscal cement leakage, KA recovery rate after 1 day, and baseline height in the univariate and multivariate logistic regression analyses. The group treated with zoledronate after KP tended to show a lower frequency of developing new VCFs than the groups treated with alendronate (P = .07), calcium (P = .05), selective estrogen receptor modulator (SERM) (P = .15), and risendronate (P = .02). This study showed that for patients with new VCFs after KP, lower BMD, greater intradiscal cement leakage, greater KA recovery rate, and lower baseline vertebral height were likely risk factors for the development of new VCFs. Additionally, among the drugs used for the treatment of osteoporosis after KP, zoledronate tends to reduce the development of new VCFs compared with other bisphosphonates, SERMs, or calcium.

Height restoration and sustainability using bilateral vertebral augmentation systems for vertebral compression fractures: a cadaveric study

BACKGROUND CONTEXT

The treatment of vertebral compression fractures using percutaneous augmentation is an effective method to reduce pain and decrease mortality rates. Surgical methods include vertebroplasty, kyphoplasty, and vertebral augmentation with implants. A previous study suggested that a titanium implantable vertebral augmentation device (TIVAD) produced superior height restoration compared to balloon kyphoplasty (BKP) but was based on a less clinically relevant biomechanical model. Moreover, the introduction of high pressure balloons and directional instruments may further aid in restoring height.

PURPOSE

The objective was to evaluate three procedures (BKP, BKP w/ Kyphon Assist (KA; directional instruments), and TIVAD) used for percutaneous augmentation of vertebral fractures with respect to height restoration and sustainability post-operatively.

STUDY DESIGN/SETTING

This is an in vitro cadaver study performed in a laboratory setting.

METHODS

Five osteoporotic female human cadaver thoracolumbar spines (age: 63-77 years, T-score: -2.5 to -3.5, levels: T7-S1) were scanned using computed tomography and dissected into 30 two-functional spine units (2FSUs). Vertebral wedge compression fractures were created by reducing the anterior height of the vertebrae by 25% and holding the maximum displacement for 15 minutes. Post-fracture, surgery was performed on each 2FSU with a constant 100 N load. Surgeries included BKP, BKP w/ KA, or TIVAD (n=10 per treatment group). Post-surgery, cyclic loading was performed on each 2FSU for 10,000 cycles at 600 N (walking), followed by 5,000 cycles at 850 N (standing up/sitting down), and 5,000 cycles at 1250 N (lifting a 5-10kg weight from the floor). Fluoroscopic images were taken and analyzed at the initial, post-fracture, post-surgery, and post-loading timepoints. Anterior, central, and posterior heights, Beck Index, and angle between endplates were assessed.

RESULTS

No difference in height restoration was observed among treatment groups (p=.72). Compared to the initial height, post-surgery anterior height was 96.3±8.7% for BKP, 94.0±10.0% for BKP w/ KA, and 95.3±5.8% for TIVAD. No difference in height sustainability in response to 600 N (p=.76) and 850 N (p=.20) load levels was observed among treatment groups. However, after 1250 N loading, anterior height decreased to 93.8±6.8% of the post-surgery height for BKP, 95.9±6.4% for BKP w/ KA, and 86.0±6.6% for TIVAD (p=.02). Specifically, the mean anterior height reduction between post-surgery and post-1250 N loading timepoints was lower for BKP w/ KA compared to TIVAD (p=.02), but not when comparing BKP to TIVAD (p=.07). No difference in Beck Index or angle between endplates was observed at any timepoint among the treatment groups.

CONCLUSIONS

The present study, utilizing a clinically relevant biomechanical model, demonstrated equivalent height restoration post-surgery and at relatively lower-level cyclic loading using BKP, BKP w/ KA, and TIVAD, contrary to results from a previous study. Less anterior height reduction in response to high-level cyclic loading was observed in the BKP w/ KA group compared to TIVAD.

CLINICAL SIGNIFICANCE

All three treatments can restore height similarly after a vertebral compression fracture, which may lead to pain reduction and decreased mortality. BKP w/ KA may exhibit less height loss in higher-demand patients who engage in physical activities that involve increased weight resistance.

Orta seviye torakal vertebra fraktürlerinde perkütan balon kifoplasti deneyimi

Aim: Balloon kyphoplasty is a popular minimally invasive technique for vertebral fractures. Although vertebral fractures occur mostly in the thoracolumbar region, compression fractures can be seen in the entire vertebral column. The mid-thoracic levels are difficult areas in terms of complications in minimally invasive procedures. Our study aimed to examine the effect of balloon kyphoplasty on vertebral height, kyphosis angle, and cement leaks as a complication in mid-thoracic vertebral fractures. Materials and Methods: Radiological images, patient files, and pathology results of patients who underwent kyphoplasty due to a single or multiple mid-thoracic vertebral fractures between 2017 and 2020 were retrospectively analyzed. Results: A total of 19 patients (9 males and 10 females) and 28 operated vertebrae were included in the study. The mean age of the patients was 58.42±18.79 (23-86) years, and the mean operation time was 40.18±15.01 minutes (17-99). The amount of cement used during the procedures was 3.68±1.13 mL (1.5-7), and postoperative cement leakage was observed in 12 levels (42.9%). Anterior and median vertebral heights and kyphosis angle improved significantly compared to preoperative values (p

Comparison between Percutaneous Kyphoplasty and Posterior Fixation Combined with Vertebroplasty in the Treatment of Stage III Kümmell’s Disease without Neurological Deficit

Objective. To evaluate the clinical and radiological outcomes of percutaneous kyphoplasty (PKP) versus posterior fixation combined with vertebroplasty PF+VP for treating stage III Kümmell’s disease (KD) patients without neurological deficits. Methods. From April 2016 to February 2020, a total of 88 patients with single-level stage III KD without neurological deficits, including 45 patients treated by PKP and 43 patients who underwent posterior fixation combined with vertebroplasty PF+VP, were retrospectively studied. The outcome parameters, including blood loss, operative time, kyphotic Cobb angle, height of vertebrae, Oswestry Disability Index (ODI), and visual analog scale (VAS) score, were compared between the PKP group and the PF+VP group. Results. The mean follow-up time was $29.3\pm 7.0$ months, ranging from 24 to 48 months. The kyphotic angle and vertebral height in both groups were significantly improved compared with those before surgery at three days, 3 months and the final follow-up. The estimated blood loss, operative time, and length of stay were significantly lower in the PKP group than in the PF+VP group ( $P<0.001$ ). The FP+VP group showed better results in kyphotic angle correction than the PKP group ( $P=0.024$ ). In the short-term follow-up (up to 3 months), the PKP group had lower VAS and ODI scores than the PF+VP group. In contrast, there were no significant differences between the two groups ( $P>0.05$ ) at the final follow-up. The average cost of PKP was lower than that of PF+VP. Conclusion. The results of our study showed that both PKP and PF+VP were safe and effective for stage III KD patients without neurological deficits. Although PF+VP presents better performance in kyphotic angle correction, PKP was associated with less surgical trauma, quicker pain relief, and lower expense than PF+VP. Therefore, it can be considered an alternative option for patients with advanced KD.

Biomechanical comparison between unilateral and bilateral percutaneous vertebroplasty for osteoporotic vertebral compression fractures: A finite element analysis

Background and objective: The osteoporotic vertebral compression fracture (OVCF) has an incidence of 7.8/1000 person-years at 55–65 years. At 75 years or older, the incidence increases to 19.6/1000 person-years in females and 5.2–9.3/1000 person-years in males. To solve this problem, percutaneous vertebroplasty (PVP) was developed in recent years and has been widely used in clinical practice to treat OVCF. Are the clinical effects of unilateral percutaneous vertebroplasty (UPVP) and bilateral percutaneous vertebroplasty (BPVP) the same? The purpose of this study was to compare biomechanical differences between UPVP and BPVP using finite element analysis.

Materials and methods: The heterogeneous assignment finite element (FE) model of T11-L1 was constructed and validated. A compression fracture of the vertebral body was performed at T12. UPVP and BPVP were simulated by the difference in the distribution of bone cement in T12. Stress distributions and maximum von Mises stresses of vertebrae and intervertebral discs were compared. The rate of change of maximum displacement between UPVP and BPVP was evaluated.

Results: There were no obvious high-stress concentration regions on the anterior and middle columns of the T12 vertebral body in BPVP. Compared with UPVP, the maximum stress on T11 in BPVP was lower under left/right lateral bending, and the maximum stress on L1 was lower under all loading conditions. For the T12-L1 intervertebral disc, the maximum stress of BPVP was less than that of UPVP. The maximum displacement of T12 after BPVP was less than that after UPVP under the six loading conditions.

Conclusion: BPVP could balance the stress of the vertebral body, reduce the maximum stress of the intervertebral disc, and offer advantages in terms of stability compared with UPVP. In summary, BPVP could reduce the incidence of postoperative complications and provide promising clinical effects for patients.

Efficacy and Safety of the Safe Triangular Working Zone Approach in Percutaneous Vertebroplasty for Spinal Metastasis

Objective

This study aimed to assess the technical feasibility, efficacy, and safety of the safe triangular working zone (STWZ) approach applied in percutaneous vertebroplasty (PV) for spinal metastases involving the posterior part of the vertebral body.

Materials and Methods

We prospectively enrolled 87 patients who underwent PV for spinal metastasis involving the posterior part of the vertebral body, with or without the STWZ approach, from January 2019 to April 2022. Forty-nine patients (27 females and 22 males; mean age ± standard deviation [SD], 57.2 ± 11.6 years; age range, 31–76 years) were included in group A (with STWZ approach), accounting for 54 vertebrae. Thirty-eight patients (18 females and 20 males; 59.1 ± 10.9 years; 29–81 years) were included in group B (without STWZ approach), accounting for 57 vertebrae. Patient demographics, procedure-related variables, and pain relief as assessed using the visual analog scale (VAS) were collected at different time points. Tumor recurrence in the vertebrae after PV was analyzed using Kaplan–Meier curves.

Results

The STWZ approach was successful from T1 to L5 without severe complications. Cement filling was satisfactory in 47/54 (87.0%) and 25/57 (43.9%) vertebrae in groups A and B, respectively (p < 0.001). Cement leakage was not significantly different between groups A and B (p = 1.000). Mean VAS score ± SD before and 1 week and 1, 3, 6, 9, and 12 months after PV were 7.6 ± 1.8, 4.2 ± 2.0, 2.7 ± 1.9, 1.9 ± 1.5, 1.7 ± 1.4, 1.7 ± 1.1, and 1.6 ± 1.3, respectively, in group A and 7.2 ± 1.7, 4.0 ± 1.3, 3.4 ± 1.6, 2.4 ± 1.2, 1.8 ± 1.0, 1.4 ± 0.5, and 1.7 ± 0.9, respectively, in group B. Kaplan–Meier analysis showed a lower tumor recurrence rate in group A than in group B (p = 0.001).

Conclusion

The STWZ approach may represent a new, safe, alternative/auxiliary approach to target the posterior part of the vertebral body in the PV for spinal metastases.

Transoral vertebroplasty for the treatment of C2 painful metastatic lesions; evaluation and outcome

OBJECTIVE

A small number of studies supports vertebroplasty at the C2 vertebral body due to the documented technical challenges, the rarity of C2 osteolytic metastatic lesions, and the existence of potentially serious consequences linked to this particular anatomical area. Vertebroplasty, in such a situation, can be performed through a transoral, an anterolateral, or an open approach. All are supported by a limited number of studies with absence of a significant clinical trial assessing the efficacy, safety, and feasibility of vertebroplasty for the C2 vertebral body. We, herein, summarize a single-institution experience on C2 transoral vertebroplasty.

PATIENTS AND METHODS

This is a retrospective analysis of the records of a single tertiary institute hospital and the clinical visits of nine patients with C2 osteolytic metastatic lesions treated by transoral fluoroscopically guided vertebroplasty between May 2016 and May 2021.

RESULTS

The median period of the last clinical follow-up was 23 months (range, 9-60 months). The intraoperative amount of polymethyl methacrylate (PMMA) injected and recorded in the surgical report was 2 mL (1.5-2.5 mL). Postoperative immediate imaging showed that the cement filling percentage in relation to the C2 mass was 70% (40-85%). The PMMA leakage through the needle track and into the paravertebral spaces was observed in only one patient (11.1%), without significant vascular and neurological consequences. Stability was maintained during the follow-up period. The postoperative median pain rating scale (PRS) score was 1 (0-2) immediately after the end of the operation and 0 (0-2) at the last visit. The recorded postoperative Pain Rating Scale (PRS) score was correlated with the cement filling percentage (rs= -0.9, p = 0.0008; Spearman correlation).

CONCLUSION

Transoral vertebroplasty is considered feasible and efficient technique in the treatment of secondary osteolytic lesions in the C2 vertebra. Further long-term and larger comparative randomized studies are required to perform a more comprehensive analysis of this technique.

Analysis of the most influential publications on vertebral augmentation for treating osteoporotic vertebral compression fracture: A review

This study aimed to analyze the most influential publications on vertebral augmentation for treating osteoporotic vertebral compression fracture. The Web of Science database was searched using the key words "percutaneous vertebroplasty," "percutaneous kyphoplasty," "balloon kyphoplasty," "vertebroplasty," "kyphoplasty," and "vertebral augmentation." The top 100 publications were arranged by citations per year and descriptively and visually analyzed. The top 100 publications were cited 25,482 times, with an average of 14.4 citations per paper per year. The corresponding authors of the publications represented 17 nations, with most authors being American (46 authors). Thirty-two journals were involved, with SPINE issuing the most publications (24 papers of the 100). Clinical research (73 of the 100 papers) outnumbered basic studies (14 papers) and systematic reviews (13 papers), and the most publications were published between 2000 and 2004. Co-citation analysis of the key words indicated that the top 5 focus areas were "complication," "balloon kyphoplasty," "vertebral compression fracture," "biomechanics," and "calcium phosphate cement." The top 3 keywords with the strongest citation bursts were "compression fracture," "cement," and "balloon kyphoplasty." The keywords with persistent strong citation bursts are "balloon kyphoplasty" and "augmentation." There are still contrary opinions about vertebral augmentation; new research should be conducted with more deliberate design and longer follow-up.

The Effects of Bone Cement Volume in Percutaneous Vertebroplasty for Thoracolumbar Junction Vertebral Compression Fractures: A Clinical Comparative Study

We compared the outcomes of patients treated with different volumes of polymethyl methacrylate bone cement during percutaneous vertebroplasty (PVP) for thoracolumbar vertebral compression fractures. We performed a comparative, retrospective study of 316 patients who underwent PVP for a single-level thoracolumbar vertebral compression fracture. Patients were divided into two groups: group A (≤5 mL; n = 146) and group B (>5 mL; n = 170). The visual analogue scale (VAS) for pain and the Roland-Morris Disability Questionnaire (RDQ) scores were compared between the two groups at 1 week and at 1, 6, 12, and 24 months after PVP. The incidence of cement leakage into the intervertebral discs was evaluated by a postoperative lateral radiograph assessment. Patients were evaluated for new fractures 1 and 2 years after PVP or when new fractures were suspected. Among the 316 patients enrolled, 245 completed the clinical research. No difference between groups A and B in terms of the VAS, RDQ, and rate of complications at all time points after surgery was observed. The presence of intervertebral disc leakage was a relative risk (RR) for subsequent total vertebral fracture (RR, 6.42; 95% confidence interval (CI), 2.72-14.19; P < 0.0001) and adjacent vertebral fracture (RR, 8.03; 95% CI, 2.74-23.54; P = 0.0001). A high volume of bone cement may increase the rate of subsequent total and adjacent vertebral fractures. However, the occurrence of intervertebral disc leakage is the principal risk factor for these negative outcomes of PVP.

A nomogram for short-term recurrent pain after percutaneous vertebroplasty for osteoporotic vertebral compression fractures

In clinical practice, it was found that some patients experienced short-term recurrent pain (SRP) in the original site after PVP treatment. This study was designed to develop and validate a nomogram for predicting the potential risks of SRP after PVP, which may help to provide a painless postoperative experience and personalized health management for patients with OVCF.

INTRODUCTION

With the aging of China's population, the incidence of osteoporotic vertebral compression fractures (OVCF) has increased significantly. Percutaneous vertebroplasty (PVP) has been widely accepted due to its minimally invasive, rapid, and effective characteristics. However, it has been found that some patients have short-term recurrent pain (SRP) in the original site after surgery in practical clinical work.

METHODS

We retrospectively reviewed the clinical data of OVCF patients who were treated with PVP in our center from January 1st, 2019, to December 30th, 2020. A total of 296 patients were enrolled in the study cohort, and patients were randomly divided into the training set (70%) and validation set (30%). Univariate and multivariate logistic regression analyses were used to determine the risk factors of SRP, and a nomogram predictive model was established accordingly. The model was evaluated by calibration curve, receiver operation characteristic (ROC) curve, and decision curve analysis (DCA).

RESULTS

Among the 296 patients, 83 (27.85%) patients experienced SRP after surgery. The independent risk factors included fracture segments (OR: 14.148, 95%CI: 1.532-130.661; p < 0.019), number of surgical vertebrae (OR: 7.896, 95%CI: 3.007-20.729; p < 0.001; (OR: 12.563, 95%CI: 2.223-70.993; p = 0.004), and smoking (OR: 3.833, 95%CI: 1.219-12.052; p = 0.022). The AUC of the prediction model was 0.819 in the training set and 0.794 in the validation set. The calibration curve and DCA indicated the good performance of this nomogram.

CONCLUSION

The nomogram prediction model had satisfactory accuracy and clinical utility, which may benefit clinical decision-making for the treatment of OVCF and strengthen patient education.

A biomechanical study of ligament tethers strengthening for the prevention of proximal junctional kyphosis after posterior long-segment spinal fusion

BACKGROUND

Proximal junctional kyphosis is a known complication of posterior long-segment thoracolumbar fusion. Here, the biomechanical effectiveness of ligament tethers strengthening and vertebral body augmentation, in proximal junctional kyphosis prevention was explored using the finite element analysis.

METHODS

Based on a validated model of T1-L5 with the pedicle screw system instrumented T8-L5, strengthening models with different strategies were created to assess the range of motion in proximal vertebrae, vertebrae stress, pedicle screw stress, and pressure on intervertebral discs during extension, flexion, lateral bending, and axial rotation motions. Strengthening strategies included two- and three-level posterior ligament tethers (TE-T7-T9 and TE-T6-T9), and tethers with T7 &T8 vertebral body augmentation (TECE-T7-T9 and TECE-T6-T9).

FINDINGS

Compared to the spinal fusion model, the ligament tethers strengthening significantly reduced the flexion-extension range of motion difference among the proximal vertebrae. During the flexion-extension motion, the T8 vertebra stresses in the TE-T7-T9, TE-T6-T9, TECE-T7-T9, and TECE-T6-T9 models were distinctively reduced, the values decreased by 26.8%, 28.3%, 28.8%, and 9.6%, respectively, during flexion, and by 21.9%, 35.2%, 23%, and 18.6%, respectively, during extension. In the strengthening models, the maximum stresses on the T7/T8 intervertebral disc in the TE-T6-T9 model were reduced by 13.8% during flexion and by 14.7% during extension.

INTERPRETATION

Based on our results, the ligament strengthening configuration of the three-level posterior tethers produced a more gradual transition in range of motion, vertebrae stresses, and intervertebral discs stress between the fused and non-fused segments, especially during flexion-extension, which may significantly decrease the proximal junctional kyphosis biomechanical risk.

Effects of Location and Volume of Intraosseous Cement on Adjacent Level of Osteoporotic Spine Undergoing Kyphoplasty: Finite Element Analysis

OBJECTIVE

Kyphoplasty (KP) is a surgery used to reduce pain and increase stability by injecting medical bone cement into broken vertebrae. The purpose of this study was to determine the ideal amount of cement and injection site by analyzing forces with the finite element method.

METHODS

We modeled the anatomical structure of the vertebra and injected the cement at T12. By increasing the amount of cement from 1 cc to 22 cc, stress applied to T11 and L1 cortical was calculated. In addition, stress applied to the adjacent KP level was calculated with different injection sites (medial, anterosuperior, posterosuperior, anteroinferior, and posteroinferior). After 5 cc cement was inserted, adjacent end plate stress was analyzed.

RESULTS

In this study, break point adjacent bone stress according to the capacity of cement was bimodal. Flexion/extension and lateral bending conditions showed similar break points (11.5-11.7 cc and 18.5-18.6 cc, respectively). When cement injection was changed, front under and back under had the highest stress values among various parts, whereas the center position showed the lowest stress value.

CONCLUSIONS

With increasing amount of bone cement, stress on the upper and lower end plates of the cemented segment increased significantly. Thus, increasing cement amount to be more than 11.5 cc has a potential risk of adjacent fracture. Centrally injected bone cement can lower the risk of adjacent fracture after percutaneous KP.

Can facet joint block be a complementary or alternative therapeutic option for patients with osteoporotic vertebral fractures: a meta-analysis

Background

Recently facet joint block has been increasingly used to relief the residual pain after vertebral augmentation, but whether it can be a complementary or alternative to vertebral augmentation remain largely unknown. Thus, we conducted this meta-analysis to determine the effect of facet joint block in the treatment of osteoporotic vertebral compression fractures (OVCF).

Methods

Following PRISMA statement, a comprehensive literature search through Embase, PubMed, Web of Science, Wanfang Data, China National Knowledge Infrastructure and Chinese BioMedical Literature Database was performed to identify relevant studies. Studies comparing vertebral augmentation combined with facet joint block (combined therapy) with vertebral augmentation, and studies comparing facet joint block with vertebral augmentation were analyzed, respectively.

Results

A total of 10 studies were included. There were seven studies comparing combined therapy with vertebral augmentation, the results showed combined therapy was associated with significantly lower visual analog scale (VAS) scores on postoperative day 1, 7, month 1, 3, and lower oswestry disability index (ODI) scores on postoperative day 1, 7, and month 3. There were three studies comparing facet joint block with vertebral augmentation, the results demonstrated vertebral augmentation only provided better analgesia in month 1 after surgery, but it was associated with a higher incidence of refracture.

Conclusions

Current evidence suggested facet joint block might be considered as a complementary to vertebral augmentation in the treatment of OVCF, but it might not be effectively used as an alternative therapy.

Using Statistical Shape and Appearance Modelling to characterise the 3D shape and material properties of human lumbar vertebrae: A proof of concept study

Patient variation affects the outcomes of a range of spinal interventions, from disc replacement to vertebral fixation and vertebroplasty. Statistical Shape and Appearance Modelling (SSAM) can be used to describe anatomical variation and pathological differences within the population. To better understand how bone density and shape variation affect load transfer with respect to surgical treatments, Finite Element (FE) models can be generated from a SSAM. The aim for this study is to understand whether geometric and density variation as well as multiple vertebral levels can be incorporated into a single SSAM and whether this can be used to investigate the relationships between, and effects of, the various modes of variation. FE models of 14 human lumbar vertebrae that had been μCT imaged and validated through experimental testing were used as input specimens for a SSAM. The validity of the SSAM was evaluated by using principal component analysis to identify the primary modes of geometric and bone density variation and comparing to those in the input set. FE models were generated from the SSAM to examine the response to loading. The mean error between the input set and generated models for volume, mean density and FE compressive stiffness were 10%, 3% and 10% respectively. Principal Component (PC) 1 captured the majority of the bone density variation. The remaining PCs described specific geometric variation. The FE models generated from the SSAM showed the variations in vertebral stiffness as a result of complex relationships between bone density and shape. The SSAM created has limited data for its input set, however, it acts as a proof of concept for the novel combination of material and shape variation into a single shape model. This approach and the tools developed can be applied to wider patient groups and treatment scenarios to improve patient stratification and to optimise treatments.

Influence of Different Surgical Timing after Percutaneous Kyphoplasty for Osteoporotic Vertebral Compression Fractures: A Retrospective Study

BACKGROUND

A large number of people suffer from osteoporotic vertebral compression fractures (OVCFs) worldwide. Percutaneous kyphoplasty (PKP), considered a minimally invasive surgery, has been widely used to treat OVCFs and achieves satisfactory outcomes. However, the surgical timing of PKP is still under discussion.

METHODS

A total of 149 patients were enrolled in the study and were divided into 3 groups according to different surgical timing. Group A (n = 52) included patients who required emergency surgery. Group B (n = 50) included patients who required surgery around a week after injury. Group C (n = 47) included patients who required surgery a month or more after injury. Characteristics of patients and radiological images were recorded. The Visual Analog Scale (VAS) scores and the Oswestry Disability Index (ODI) scores were analyzed before, 1 day, 1 month, and 6 months after surgery. In addition, compression rates of anterior vertebral height (AVH) were calculated and the kyphosis Cobb angle was measured before and after surgery.

RESULTS

There was a significant difference in the VAS and ODI scores between the three groups at 1 day, 1 month, and 6 months after PKP. The VAS and ODI scores of Group C were higher than those of Groups A and B. The AVH compression rates of Group C were significantly higher than those of Groups A and B postoperatively 1 day, 1 month, and 6 months. The kyphosis Cobb angles in Group C was significantly larger than those in Groups A and B at 1 day and 1 month after PKP.

CONCLUSIONS

Emergency PKP showed more advantages in both clinical and radiological outcomes. We recommend early PKP for the treatment of OVCFs.

A Nomogram for Predicting the Residual Back Pain after Percutaneous Vertebroplasty for Osteoporotic Vertebral Compression Fractures

OBJECTIVE

Current findings suggest that percutaneous vertebroplasty (PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). However, a significant minority of patients still experience residual back pain after PVP. The present retrospective study was designed to determine the risk factors for residual back pain after PVP and provides a nomogram for predicting the residual back pain after PVP.

METHODS

We retrospectively reviewed the medical records of patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into group N and group R according to the postoperative VAS score. Group R is described as the VAS score of residual back pain ≥ 4. Pre- and postoperative factors that may affect back pain relief were evaluated between two groups. Univariate and multivariate logistic regression analysis were performed to identify risk factors affecting residual back pain after PVP. We provided a nomogram for predicting the residual back pain and used the receiver operating characteristic curve (ROC), concordance index (C-index), calibration curve, and decision curve analyses (DCA) to evaluate the prognostic performance.

RESULTS

Among 268 patients treated with PVP, 37 (13.81%) patients were classified postoperative residual back pain. The results of the multivariate logistical regression analysis showed that the presence of an intravertebral vacuum cleft (IVC) (OR 3.790, P=0.026), posterior fascia oedema (OR 3.965, P=0.022), severe paraspinal muscle degeneration (OR 5.804, P=0.01; OR 13.767, P < 0.001), and blocky cement distribution (OR 2.225, P=0.041) were independent risk factors for residual back pain after PVP. The AUC value was 0.780, suggesting that the predictive ability was excellent. The prediction nomogram presented good discrimination, with a C-index of 0.774 (0.696∼0.852) and was validated to be 0.752 through bootstrapping validation. The calibration curve of the nomogram demonstrated a good consistency between the probabilities predicted by the nomogram and the actual probabilities. The nomogram showed net benefits in the range from 0.06 to 0.66 in DCA.

CONCLUSIONS

The presence of IVC, posterior fascia oedema, blocky cement distribution, and severe paraspinal muscle degeneration were significant risk factors for residual back pain after PVP for OVCFs. Patients with OVCFs after PVP who have these risk factors should be carefully monitored for the possible development of residual back pain. We provide a nomogram for predicting the residual back pain after PVP.

Survival analysis and risk factors of new vertebral fracture after vertebroplasty for osteoporotic vertebral compression fracture

BACKGROUND CONTEXT

Although risk factors of new adjacent vertebral fracture (AVF) and remote vertebral fracture (RVF) after vertebroplasty may differ, research on this topic is lacking.

PURPOSE

To determine the natural course of new vertebral fractures after vertebroplasty for osteoporotic vertebral compression fracture (OVCF) and to analyze each risk factor for understanding the incidence of AVF and RVF.

STUDY DESIGN

Retrospective cohort study.

PATIENT SAMPLE

The study subjects included 205 patients who received vertebroplasty for OVCF and were followed-up for at least 1-year.

OUTCOME MEASURES

Data on factors that could affect the occurrence of vertebral fractures, such as age, body mass index, and bone density, were collected from the patients' medical records. Fracture pattern, fracture location, sagittal imbalance, degree of segmental kyphosis after vertebroplasty, cement distribution, and cement leakage were radiologically examined.

METHODS

xDuring the follow-up period, any newly developed vertebral fractures were identified. We analyzed whether the time of occurrence differed between AVF and RVF by performing a survival analysis and each risk factor separately.

RESULTS

New vertebral fractures occurred in 47 patients (22.9%) after vertebroplasty, AVF occurred in 21 patients (10.2%), and RVF occurred in 26 patients (12.7%). The onset time of AVF was 6.2±1.8 months after vertebroplasty, showing a significant difference from that of RVF, which was 15.2±1.8 months (p<.001). In the univariate analysis, the risk factors of AVF included severe osteoporosis (T-score<-3.0), vertebroplasty in the thoracolumbar junction, sagittal imbalance, and segmental kyphosis angle >15° (p=0.029, p=0.033, p=0.001, and p=0.021, respectively). The risk factors of RVF included severe osteoporosis (T-score <-3.0) and sagittal imbalance (p=0.013 and p=0.004). In the multivariate analysis, the risk factors of AVF included vertebroplasty in the thoracolumbar junction and sagittal imbalance (hazard ratio=3.34, p=0.032 and hazard ratio=4.05, p=0.008), and those of RVF included only sagittal imbalance (hazard ratio=2.66, p=0.024).

CONCLUSON

After vertebroplasty for OVCF, a significant difference in the meantime of occurrence was found; it took 6 months for AVF and 15 months for RVF to develop. Vertebroplasty in the thoracolumbar junction was identified as a risk factor for AVF, whereas sagittal imbalance was a risk factor of both AVF and RVF.

A biomechanical study of proximal junctional kyphosis after posterior long segment fusion with vertebral body augmentation

Background Proximal junction kyphosis is a common clinical complication of posterior long-segment spinal fusion and vertebral body augmentation method is one of the effective approaches to prevent it. The purpose of this study was to explore the biomechanical effect of proximal junction kyphosis after posterior long-segment thoracolumbar fusion with different vertebral augmentation schemes using finite element analysis. Methods 3D nonlinear finite element models of T1-L5 spine posterior long-segment T8-L5 thoracolumbar fusion combined with T7, T8 and T7&T8 vertebral bone cement augmentation were constructed from human spine CT data and clinical surgical operation scheme to analyze the von Mises stress in the vertebrae, intervertebral discs pressure and pedicle screws system loads under the flexion, extension, lateral bending and axial rotation motion. Findings Compared with thoracolumbar posterior long-segment fusion model, T7 maximum stress in T7, T8 and T7&T8 vertebrae augmentation models were reduced by 8.64%, 7.17%, 8.51%;0.79%, -3.88%,1.67%;4.02%, 5.30%, 4.27% and 3.18%, 3.06%, -6.38% under the flexion, extension, lateral bending and axial rotation motion. T7/T8 intervertebral disc pressure in T7, T8, T7&T8 vertebral augmentation models were 36.71Mpa,29.78Mpa,36.47Mpa;22.25Mpa,18.35Mpa,22.06Mpa;84.27Mpa,68.17Mpa, 83.89Mpa and 52.23Mpa, 38.78Mpa,52.10Mpa under the same condition. The maximum stress 178.2Mpa of pedicle screws is mainly distributed at the root of screw. Interpretation Thoracolumbar posterior long-segment fusion with proximal double-segment vertebral augmentation should be recommended to prevent proximal junction kyphosis than single-segment augmentation. Simulation results can provide theoretical foundations and assist surgeons in selecting the appropriate operation scheme.

Clinical observation of two bone cement distribution modes after percutaneous vertebroplasty for osteoporotic vertebral compression fractures

Background

Current findings suggest that percutaneous vertebroplasty(PVP) is a suitable therapeutic approach for osteoporotic vertebral compression fractures (OVCFs). The present retrospective study aimed to investigate the differences in clinical efficacy and related complications between the two bone cement distribution modes.

Methods

We retrospectively reviewed the medical records of the patients with single-segment OVCFs who underwent bilateral percutaneous vertebroplasty. Patients were divided into blocky and spongy group according to the type of postoperative bone cement distribution. Clinical efficacy and related complications was compared between the two bone cement distribution modes on 24 h after the operation and last follow-up.

Results

A total of 329 patients with an average follow up time of 17.54 months were included. The blocky group included 131 patients, 109 females(83.2 %) and 22 males(16.8 %) with a median age of 72.69 ± 7.76 years, while the Spongy group was made up of 198 patients, 38 females(19.2 %) and 160 males(80.8 %) with a median age of 71.11 ± 7.36 years. The VAS and ODI after operation improved significantly in both two groups. The VAS and ODI in the spongy group was significantly lower than that in the blocky group, 24 h postoperatively, and at the last follow-up. There were 42 cases (12.8 %) of adjacent vertebral fractures, 26 cases (19.8 %) in the blocky group and 16 cases (8.1 %) in the spongy group. There were 57 cases (17.3 %) of bone cement leakage, 18 cases (13.7 %) in blocky group and 39 cases (19.7 %) in the spongy group. At 24 h postoperatively and at the last follow-up, local kyphosis and anterior vertebral height were significantly corrected in both groups, but gradually decreased over time, and the degree of correction was significantly higher in the spongy group than in the block group. The change of local kyphosis and loss of vertebral body height were also less severe in the spongy group at the last follow-up.

Conclusions

Compared with blocky group, spongy group can better maintain the height of the vertebral body, correct local kyphosis, reduce the risk of the vertebral body recompression, long-term pain and restore functions.

Iodine-125 radioactive seed brachytherapy as a treatment for spine and bone metastases: A systematic review and meta-analysis

AIM

To evaluate the analgesic efficacy, safety, and local tumor control of iodine-125 (¹²⁵I) seed brachytherapy (BT) for the management of spine and bone metastases.

METHODS

A systematic literature search was conducted using PubMed, the Cochrane Library, and Scopus databases. Data regarding patient demographics, tumor characteristics, procedural parameters, and clinical outcomes were extracted and analyzed.

RESULTS

Fourteen studies (7 prospective, 7 retrospective) were included, accounting for 689 patients, in our review. Analgesic efficacy was assessed at baseline and various postoperative time points. Significant improvement in pain was noted at 4- and 24-week follow-ups (p < 0.01). Interestingly, all studies that combined ¹²⁵I seed BT with cement augmentation reported relatively higher levels of pain reduction (mean pain reduction ≥4 points) as compared to the studies which applied ¹²⁵I seed BT as a stand-alone therapy (mean pain reduction ≥2 points), at the last follow-up. Local tumor control rates ranged widely from 14% to 100% at varying follow-ups. Median overall survival ranged between 10 months and 25 months. The overall complication rate was 19% (130/689) and mainly included minor subcutaneous hemorrhage, fever, myelosuppression, and seed displacement. Metrics assessing performance and quality of life demonstrated significant improvements from baseline to posttreatment.

CONCLUSION

¹²⁵I seed BT, alone or in conjunction with cement augmentation, may be a viable salvage therapy in appropriately selected patients. However, further studies are needed to analyze the long-term efficacy of this intervention as a palliative and curative modality.

Differentiation Between Osteoporotic And Neoplastic Vertebral Fractures: State Of The Art And Future Perspectives

Vertebral fractures are a common condition, occurring in the context of osteoporosis and malignancy. These entities affect a group of patients in the same age range; clinical features may be indistinct and symptoms non-existing, and thus present challenges to diagnosis. In this article, we review the use and accuracy of different imaging modalities available to characterize vertebral fracture etiology, from well-established classical techniques, to the role of new and advanced imaging techniques, and the prospective use of artificial intelligence. We also address the role of imaging on treatment. In the context of osteoporosis, the importance of opportunistic diagnosis is highlighted. In the near future, the use of automated computer-aided diagnostic algorithms applied to different imaging techniques may be really useful to aid on diagnosis.

Clinical Efficacy and Safety of Zoledronic Acid Combined with PVP/PKP in the Treatment of Osteoporotic Vertebral Compression Fracture: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective

We conducted this meta-analysis to provide better evidence of the efficacy and safety of zoledronic acid (ZA) combined with percutaneous vertebroplasty/kyphoplasty (PVP/PKP) on osteoporotic vertebral compression fracture (OVCF) and proposed a protocol for its application in clinical practice.

Methods

All randomized controlled trials (RCTs) of ZA combined with PVP or PKP compared to individual PVP/PKP for the management of patients with OVCFs were included in this study. Electronic database searches were conducted from database inception to November 2020, including the Cochrane Library, PubMed, Web of Science, and Embase. The pooled data were analyzed using RevMan 5.3 software.

Results

Seven RCTs with 929 subjects were finally included. All included studies reported visual analog scores (VAS), and no statistically significant differences were identified at follow-ups of 3 d and 1 w (P > 0.05). In contrast, significant differences were observed at the 1 mo, 3 mo, 6 mo, and 12 mo follow-ups (P < 0.05). Two trials reported the Cobb angle and vertebral body height (VBH), including 182 subjects without significant differences at the 12 mo follow-up (P > 0.05). In addition, significant differences in the bone mineral density (BMD), β-isomerized C-terminal telopeptide of type I collagen (β-CTX), N-terminal propeptide of type I collagen (PINP), and N-terminal molecular fragment (N-MID) levels were observed between the two groups (P < 0.05). All trials reported side effects. Significant differences in recurrent fractures, fever, flu-like symptoms, and arthralgia or myalgia were identified (P < 0.05); however, no significant difference in postoperative leakage was detected (P > 0.05).

Conclusion

Compared to PVP/PKP alone, an additional ZA injection had advantages of long-term analgesic effects with improved bone metabolism indexes. Moreover, combination therapy significantly prevented complications and drug reactions were well tolerated. Overall, this systematic review revealed that ZA combined with PVP/PKP was an effective, safe, and comprehensive therapy for patients with OVCFs.

Functional Properties of Low-Modulus PMMA Bone Cements Containing Linoleic Acid

Acrylic bone cements modified with linoleic acid are a promising low-modulus alternative to traditional high-modulus bone cements. However, several key properties remain unexplored, including the effect of autoclave sterilization and the potential use of low-modulus cements in other applications than vertebral augmentation. In this work, we evaluate the effect of sterilization on the structure and stability of linoleic acid, as well as in the handling properties, glass transition temperature, mechanical properties, and screw augmentation potential of low-modulus cement containing the fatty acid. Neither 1H NMR nor SFC-MS/MS analysis showed any detectable differences in autoclaved linoleic acid compared to fresh one. The peak polymerization temperature of the low-modulus cement was much lower (28-30 °C) than that of the high-modulus cement (67 °C), whereas the setting time remained comparable (20-25 min). The Tg of the low-modulus cement was lower (75-78 °C) than that of the high-stiffness cement (103 °C). It was shown that sterilization of linoleic acid by autoclaving did not significantly affect the functional properties of low-modulus PMMA bone cement, making the component suitable for sterile production. Ultimately, the low-modulus cement exhibited handling and mechanical properties that more closely match those of osteoporotic vertebral bone with a screw holding capacity of under 2000 N, making it a promising alternative for use in combination with orthopedic hardware in applications where high-stiffness augmentation materials can result in undesired effects.

A novel and convenient method to evaluate bone cement distribution following percutaneous vertebral augmentation

A convenient method to evaluate bone cement distribution following vertebral augmentation is lacking, and therefore so is our understanding of the optimal distribution. To address these questions, we conducted a retrospective study using data from patients with a single-segment vertebral fracture who were treated with vertebral augmentation at our two hospitals. Five evaluation methods based on X-ray film were compared to determine the best evaluation method and the optimal cement distribution. Of the 263 patients included, 49 (18.63%) experienced re-collapse of treated vertebrae and 119 (45.25%) experienced new fractures during follow-up. A 12-score evaluation method (kappa value = 0.652) showed the largest area under the receiver operating characteristic curve for predicting new fractures (0.591) or re-collapse (0.933). In linear regression with the 12-score method, the bone cement distribution showed a negative correlation with the re-collapse of treated vertebra, but it showed a weak correlation with new fracture. The two prediction curves intersected at a score of 10. We conclude that an X-ray-based method for evaluation of bone cement distribution can be convenient and practical, and it can reliably predict risk of new fracture and re-collapse. The 12-score method showed the strongest predictive power, with a score of 10 suggesting optimal bone cement distribution.

Comparison Between 7 Osteoporotic Vertebral Compression Fractures Treatments: Systematic Review and Network Meta-analysis

BACKGROUND

Vertebroplasty (VP), kyphoplasty (KP), SpineJack system (SJ), radiofrequency kyphoplasty (RFK), Kiva system (Kiva), Sky kyphoplasty system (SK), and conservative treatment are widely used in the treatment of osteoporotic vertebral compression fractures (OVCFs). However, it is still unknown which is the best intervention. The aim of the current study was to evaluate the effectiveness and safety of VP, KP, SJ, RFK, Kiva, SK, and CT in the treatment of OVCFs.

METHODS

Randomized controlled trials and cohort studies comparing VP, KP, SJ, RFK, Kiva, SK, or CT for the treatment of OVCFs were identified on the basis of databases including PubMed, the Cochrane Library, Web of Science, and Springer Link. A network meta-analysis was performed using STATA 15.1.

RESULTS

A total of 56 studies with 6974 patients and 7 interventions were included in this study. The results of the surface under the cumulative probability demonstrated that SK was the best intervention in decreasing VAS scores and recovering middle vertebral height, RFK was the best intervention in improving ODI scores and decreasing incidence of new fractures, SJ was the best intervention to restore kyphosis angle, and Kiva was the best intervention to reduce incidence of bone cement leakage. Cluster analysis showed that SK was the preferable intervention on the basis of the outcomes of VAS, ODI, middle vertebral height, and kyphotic angle, and RFK was the preferable treatment in decreasing the incidence of adverse events. In our network meta-analysis, node-splitting analysis and loop inconsistency analysis showed no significant inconsistencies.

CONCLUSIONS

SK may be the most effective treatment in relieving pain, improving the quality of life, and recovering vertebral body height and kyphotic angle, while RFK may be the safest intervention for OVCFs. However, considering the limitations of this study, more high-quality trials are needed in the future to confirm the current conclusion.

How the clinical dosage of bone cement biomechanically affects adjacent vertebrae

Objective

This study evaluated the biomechanical changes in the adjacent vertebrae under a physiological load (500 N) when the clinically relevant amount of bone cement was injected into fractured cadaver vertebral bodies.

Methods

The embalmed cadaver thoracolumbar specimens in which each vertebral body (T12–L2) had a BMD of < 0.75 g/cm² were used for the experiment. For establishing a fracture model, the upper one third of the L1 vertebra was performed wedge osteotomy and the superior endplate was kept complete. Stiffness of specimens was measured in different states. Strain of the adjacent vertebral body and intervertebral disc were measured in pre-fracture, post-fracture, and after augmentation by non-contact optical strain measurement system.

Results

The average amount of bone cement was 4.4 ml (3.8–5.0 ml). The stiffness of after augmentation was significantly higher than the stiffness of post-fracture (p < 0.05), but still lower than pre-fracture stiffness (p < 0.05). After augmentation, the adjacent upper vertebral strain showed no significant difference (p > 0.05) with pre-fracture, while the strain of adjacent lower vertebral body was significantly higher than that before fracture (p < 0.05). In flexion, T12/L1 intervertebral disc strain was significantly greater after augmentation than after the fracture (p < 0.05), but there was no significant difference from that before the fracture (p > 0.05); L1/2 vertebral strain after augmentation was significantly less than that after the fracture (p < 0.05), but there was no significant difference from that before the fracture (p > 0.05).

Conclusions

PVP may therefore have partially reversed the abnormal strain state of adjacent vertebral bodies which was caused by fracture.

The effect of bone cement distribution on the outcome of percutaneous Vertebroplasty: a case cohort study

Background

To analyze the effect of different types of bone cement distribution after percutaneous vertebroplasty (PVP) in patients with osteoporotic vertebral compression fracture (OVCF).

Methods

One hundred thirty seven patients with single level OVCF who underwent PVP were retrospectively analyzed. The patients were divided into two groups according to bone cement distribution. Group A: bone cement contacted both upper and lower endplates; Group B: bone cement missed at least one endplate. Group B was divided into 3 subgroups. Group B1: bone cement only contacted the upper endplates; Group B2: bone cement only contacted the lower endplates; Group B3: bone cement only located in the middle of vertebral body. The visual analogue scale (VAS) score at 24 h post operation and last follow-up, anterior vertebral height restoration ratio (AVHRR), anterior vertebral height loss ratio (AVHLR), local kyphotic angle change and vertebral body recompression rate were compared.

Results

24 h post operation, the pain of all groups were significantly improved. The average follow-up time was 15.3 ± 6.3 (6–24) months. At last follow-up, the VAS score of group A was lower than that of group B. There were 14 cases (10.2%) of adjacent vertebral fracture, 5 cases (8.6%) in group A and 9 cases (11.4%) in group B. There were 9 cases (6.6%) of cement leakage, 4 cases (6.9%) in group A and 5 cases (6.3%) in group B. At last follow-up, there were 16 cases (11.7%) of vertebral body recompression, including 3 cases (5.2%) in group A and 13 cases (16.5%) in group B. There was no significant difference in AVHRR between two groups. Local kyphotic angle change was significant larger in group B. At last follow-up, AVHLR in group B was higher than that in group A. Analysis in subgroup B revealed no significant difference in VAS score, local kyphotic angle change, vertebral recompression rate, AVHRR or AVHLR.

Conclusions

If the bone cement fully contacted both the upper and lower endplates, it can better restore the strength of the vertebral body and maintain the height of the vertebral body, reduce the risk of the vertebral body recompression and long-term pain.

Modified percutaneous Kyphoplasty technique in the treatment of osteoporotic thoracolumbar burst fractures: could it reduce the odds of cement leakage?

Background

Osteoporotic thoracolumbar burst fracture (OTLBF) is common in seniors. Due to the fracture of the posterior vertebra and spinal canal occupancy, the risk of cement leakage and spine injury is high in OTLBF patients, thus the application of vertebroplasty and kyphoplasty is limited in these patients. This study aims to investigate the efficacy and safety of the modified percutaneous kyphoplasty (MPKP) in the treatment of OTLBF.

Methods

Clinical data of the OTLBF patients treated with MPKP and the osteoporotic thoracolumbar compression fracture (OTLCF) patients undergone PKP from January 2014 to June 2016 were collected. The key procedure of the MPKP was to fill the bone cavity with gel-foam by the first balloon inflation and to press the gel-foam by a second balloon inflation. Pain intensity, Oswestry disability index (ODI), and bone cement leakage of the patients in the two groups were analyzed.

Results

In the burst fracture group, the overall spinal canal occupancy was relatively low, and the maximum occupancy was 1/3 of the sagittal diameter of the spinal canal. The surgical duration was longer in the burst fracture group (39.0 ± 5.0 min with 95% CI: 37.7, 40.3) than in the compression fracture group (31.7 ± 4.3 min with 95% CI: 31.1, 32.3), and the difference between the two groups was statistically significant (Z = -8.668 and P = 0.000). Both the Oswestry disability index (ODI) and the visual analog scales (VAS) were apparently improved, but there was no significant difference between the two groups. Cement leakage occurred in 13 out of the 53 cases (24.5%) in the burst fracture group and 35 out of the 193 cases (18.1%) in the compression fracture group, and there was no significant difference between the two groups (Z = − 1.038 and P = 0.299). Neither group had consequential symptoms, such as spinal cord lesion, pain, and numbness of the peripheral nerve.

Conclusion

Similar to the efficacy of PKP in the treatment of OTLCF, MPKP efficiently reduced the cement leakage rate and improved the safety of the surgery, although it prolonged the surgical duration and introduced more surgical steps.

Optimizing computational methods of modeling vertebroplasty in experimentally augmented human lumbar vertebrae

Vertebroplasty has been widely used for the treatment of osteoporotic compression fractures but the efficacy of the technique has been questioned by the outcomes of randomized clinical trials. Finite-element (FE) models allow an investigation into the structural and geometric variation that affect the response to augmentation. However, current specimen-specific FE models are limited due to their poor reproduction of cement augmentation behavior. The aims of this study were to develop new methods of modeling the vertebral body in both a nonaugmented and augmented state. Experimental tests were conducted using human lumbar spine vertebral specimens. These tests included micro-computed tomography imaging, mechanical testing, augmentation with cement, reimaging, and retesting. Specimen-specific FE models of the vertebrae were made comparing different approaches to capturing the bone material properties and to modeling the cement augmentation region. These methods significantly improved the modeling accuracy of nonaugmented vertebrae. Methods that used the registration of multiple images (pre- and post-augmentation) of a vertebra achieved good agreement between augmented models and their experimental counterparts in terms of predictions of stiffness. Such models allow for further investigation into how vertebral variation influences the mechanical outcomes of vertebroplasty.