Analysis of Adjacent Fractures after Two-Level Percutaneous Vertebroplasty: Is the Intervening Vertebral Body Prone to Re-fracture?

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.

Finite element investigation of the influence of a new transpedicular vertebral implant positioning on biomechanical responses of the spine segment

The optimal positioning of an implant into a living organ such as femurs and vertebra is still an open problem. In particular, vertebral implant position has a significant impact on the results on spine behaviour after treatment in terms of stiffness, range of motion (ROM), wear, loosening and failure. In the current work, a 3D finite element analysis was conducted to investigate the positioning parameters of a novel transpedicular implant (V-STRUT©, Hyprevention, France) in terms of placement of the implant in the treated vertebra. The implant was designed in order to strength osteoporotic vertebral body and the related spine segment under compressive load. The effects of the axial and sagittal positions of the implant in the treated vertebra was investigated in terms of stress and stiffness variations. A 3D finite element model of an osteoporotic spine segment was built based on a Computed Tomography (CT) scan of an osteoporotic female (69 yo). The model is composed of T12, L1 and L2 vertebrae and corresponding intervertebral discs and ligaments. The bone tissue was modeled as a heterogeneous material with properties assigned based on the grey scale levels. The intervertebral discs were modeled using two regions describing the annulus and the nucleus and linear beam elements with specific stiffness each were used representing each ligament. The simulations indicated that the sagittal position (distance d) plays a role on the stress distribution. The closer the implant to the interior wall the lower the stress applied to the spine segment. Nevertheless, the axial plane position (distance h) have limited effects on the stress applied to the bone with a higher stress applied to the device (subjected to a higher bending load). These results can have direct clinical implications when dealing with the optimal placement of the implant. It is also possible to select a particular position in order to assign a given (target) stiffness for a patient.

Intravertebral insertion of interbody fusion cage via transpedicular approach for the treatment of stage III Kümmell disease: a technical note and case presentation

BACKGROUND

Kümmell disease usually occurs in the elderly osteoporosis population and develops gradually into symptomatic, progressive kyphosis of the spine. However, current surgical methods to deal with stage III Kümmell disease are less satisfying. The objective of this study was to describe a less invasive technique for treating stage III Kümmell disease.

TECHNIQUE

A less invasive technique of intravertebral insertion of interbody fusion cage via transpedicular approach with posterior spine stabilization was applied to treat stage III Kümmell disease.

RESULTS

This study details a modified technique applied in a patient with stage III Kümmell disease, showing significant improvement in pain relief, anterior column height recovery, and kyphotic angle correction. And no complications were reported during our follow-up.

CONCLUSIONS

Intravertebral insertion of interbody fusion cage via transpedicular approach provides advantages of acceptable correction of kyphosis, bony fusion, minimal invasion. Thus, our method was a good alternative choice for stage III Kümmell disease.

Beyond Pain Relief: An In-Depth Review of Vertebral Height Restoration After Balloon Kyphoplasty in Vertebral Compression Fractures

This comprehensive review delves into the intricate landscape of vertebral height restoration after balloon kyphoplasty in cases of vertebral compression fractures. With a comprehensive examination of procedural intricacies, radiological evaluations, clinical outcomes, and influential factors, a nuanced comprehension unfolds. Beyond its immediate alleviation of pain, vertebral height restoration emerges as a linchpin in enhancing spinal alignment, fostering functional recuperation, and augmenting the overall quality of life. This review underscores the pivotal role of balloon kyphoplasty, transcending its mere medical utility to become a conduit for renewed independence and well-being among individuals grappling with vertebral compression fractures. The ongoing advancements in medical science and the continued pursuit of research stand poised to amplify the significance of vertebral height restoration, manifesting a promising horizon for individuals seeking respite from pain, a revitalised capacity for movement, and a life unburdened by its constraints.

Effect of a new transpedicular vertebral device for the treatment or prevention of vertebral compression fractures: A finite element study

BACKGROUND

A finite element study was performed to investigate the biomechanical performance of a novel transpedicular implant (V-STRUT©, Hyprevention, France) made of PEEK (polyetheretherketone) material in terms of strengthening the osteoporotic vertebra and the thoraco-lumbar spine. The objective was to assess numerically the efficacy of the implant to reduce the stress distribution within bone and absorb part of the stress by the implant thanks to its optimized material selection close to that of normal bone.

METHODS

A numerical model was generated based on a scan of an osteoporotic patient. The model is composed of three consecutive vertebrae and intervertebral discs. A heterogeneous distribution of bone material properties was assigned to the bone. In order to investigate the rationale of the device material selection, three FE models were developed (i) without the device to serve a reference model, (ii) with device made in Titanium material and (iii) with device made in PEEK material. Stiffness and stress distribution within the spine segment were computed and compared in order to assess the implants' performances.

FINDINGS

The results obtained by the simulations indicated that the novel transpedicular implant made of PEEK material provided support to the superior vertebral endplate, restored the thoraco-lumbar spine segment stiffness and reduced the stress applied to the vertebrae under the compressive load.

INTERPRETATION

Implant geometry in combination with its material properties are very important factors to restore vertebral strength and stiffness and limiting the risk of fracture at the same vertebra or adjacent ones.

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.

Lumbar posterior group muscle degeneration: Influencing factors of adjacent vertebral body re-fracture after percutaneous vertebroplasty

Objective

The purpose of the study was to explore the influencing factors of adjacent vertebral re-fracture after percutaneous vertebroplasty (PVP) for osteoporosis vertebral compression fractures (OVCFs).

Methods

We retrospectively analyzed the clinical data of 55 patients with adjacent vertebral re-fracture after PVP operation for OVCFs in our hospital from January 2016 to June 2019, they were followed up for 1 year and included in the fracture group. According to the same inclusion and exclusion criteria, we collected the clinical data of 55 patients with OVCFs without adjacent vertebral re-fracture after PVP in the same period and included them in the non-fracture group. We performed univariate and multivariate logistic regression analysis on the influencing factors of adjacent vertebral re-fracture in patients with OVCFs after PVP.

Results

There were significant differences in body mass index (BMI), bone mineral density (BMD) T-value, amount of bone cement injected, bone cement leakage, history of glucocorticoid use, cross-sectional area (CSA), cross-sectional area asymmetry (CSAA), fat infiltration rate (FIR), and fat infiltration rate asymmetry (FIRA) of lumbar posterior group muscles [multifidus (MF) and erector spinae (ES)] between the two groups (p < 0.05). There was no significant difference in sex, age, or time from the first fracture to operation, the CAS, CSAA, FIR, and FIRA of psoas major (PS) between the two groups (p > 0.05). Multivariate logistic regression showed that a higher dose of bone cement, greater CSAA and FIR of multifidus, and higher CSAA of erector spinae were independent risk factors for recurrent fractures of adjacent vertebrae after PVP.

Conclusion

There are many risk factors for recurrent vertebral fracture after PVP in patients with OVCFs, and degeneration of paraspinal muscles (especially posterior lumbar muscles) may be one of the risks.

Do sandwich vertebral bodies increase the risk of post-augmentation fractures? A retrospective cohort study

Until now, there have been only a few retrospective studies that focused on the outcomes of sandwich vertebral bodies (SVBs). This is a long-term retrospective cohort study to investigate the SVBs. We found that although patients with SVBs had a relatively high risk of developing new fractures after VA, the incidence rate of new fractures was not significantly different from that of the control group. However, the statistical power of this study was very limited. Therefore, and because the refracture rate in these patients is substantial, routine long-term monitoring of patients after VA for osteoporosis is strongly recommended.

BACKGROUND

Sandwich vertebral bodies (SVBs) are intact unaugmented vertebral bodies between two previously augmented vertebrae. Until recently, only a few studies have reported the outcomes and strategies for SVBs. This retrospective cohort study aimed to describe the clinical features and incidence of new fractures in patients with SVBs.

METHODS

The clinical data were collected from 179 patients with 237 symptomatic osteoporotic vertebral compression fractures who underwent vertebral augmentation (VA). Among them, 23 patients with 24 levels of SVBs were included. Spinal radiographs (X-ray and CT) of all patients were evaluated prior to surgery 1 day after primary VA and during follow-up.

RESULTS

All patients successfully underwent PKP with an average follow-up period of 21.48 months. Asymptomatic cement leakage occurred in four patients (17.4%), and eight patients (34.8%) developed new fractures following primary PKP, including four sandwich, six adjacent, four remote vertebral fractures, and one re-collapse of cemented vertebrae. The incidence of new fractures in the SVB and control groups was 16.7% (4/24) and 13.0% (6/46), respectively, but there was no significant difference.

CONCLUSIONS

Although patients with SVBs had a relatively high risk of developing new fractures after VA, the incidence rate of new fractures was not significantly different from that of the control group. However, the statistical power of this study was very limited. Therefore, and because the refracture rate in these patients is substantial, routine long-term monitoring of patients after VA for osteoporosis is strongly recommended.

Treatment of Kümmell’s disease following the occurrence of osteoporotic vertebral compression fracture

Background: The incidence of osteoporotic vertebral compression fracture (OVCF) is increasing with the increase in the elderly population. Kümmell’s disease following OVCF occurrence is not a rare complication and is frequently associated with severe pain or neurologic deficit with progressive kyphotic deformity. Kümmell’s disease initially meant post-traumatic delayed vertebral collapse, but now it is also termed nonunion, osteonecrosis, or intravertebral vacuum cleft, all of which suggest the disruption of the healing process.Current Concepts: The major pathogenesis of Kümmell’s disease is a vascular compromise caused by mechanical stress or intravascular pathology. The key radiologic sign to diagnose Kümmell’s disease is the presence of intravertebral vacuum cleft, observed using simple X-ray, computed tomography, or magnetic resonance imaging. Magnetic resonance imaging is the most useful diagnostic tool showing gas or fluid signals. The risk factors for the progression of Kümmell’s disease after OVCF include middle-column injury, confined low signal intensity on T2-weighted image, posterior wall combined fracture, kyphotic angle >10°, and a height loss >15%. Its treatment can be broadly classified as conservative treatment, bone cement injection, and surgical treatment. The appropriate treatment method is selected based on the pain intensity, neurological symptoms, and the severity of the kyphotic deformity.Discussion and Conclusion: Kümmell’s disease usually develops along with osteoporosis. Therefore, the treatment should be focused on relief from symptoms associated with Kümmell’s disease and osteoporosis. It is recommended that an anabolic agent should be administered after the diagnosis of Kümmell’s disease, regardless of the treatment modality.

[Comparison of refracture risk between sandwich vertebrae and ordinary adjacent vertebrae]

Objective

To compare the refracture risk between sandwich vertebrae and ordinary adjacent vertebrae, and to explore the risk factors related to refracture.

Methods

Retrospective analysis was performed on the data of patients who received percutaneous vertebral augmentation (PVA) and formed sandwich vertebrae between April 2015 and October 2019. Of them, 115 patients were enrolled in the study. There were 27 males and 88 females with an average age of 73.9 years (range, 53-89 years). Univariate analysis was performed to analyzed the patients' general data, vertebral augmentation related indexes, and sandwich vertebrae related indexes. Survival analysis was performed for all untreated vertebrae at T ₄-L ₅ of the included patients at the vertebra-specific level, and risk curves of refracture probability of untreated vertebrae between sandwich vertebrae and ordinary adjacent vertebrae were compared. Cox's proportional hazards regression model was used to analyze risk factors for refracture.

Results

The 115 patients were followed up 12.6-65.9 months (mean, 36.2 months). Thirty-seven refractures involving 51 vertebral bodies occurred in 31 patients. The refracture rate of 27.0% (31/115) in patients with sandwich vertebrae was significantly higher than that of 15.2% (187/1228) in all patients who received PVA during the same period ( χ ²=10.638, P=0.001). Univariate analysis results showed that there was a significant difference in the number of augmented vertebrae between patients with and without refractures ( Z=0.870, P=0.004). However, there was no significant difference in gender, age, body mass index, whether had clear causes of fracture, whether had dual energy X-ray absorptiometry testing, whether the sandwich vertebra generated through the same PVA, puncture method, method of PVA, number of PVA procedures, number of vertebrae with old fracture, whether complicated with spinal deformity, bone cement distribution, and kyphosis angle of sandwich vertebral area ( P>0.05). Among the 1 293 untreated vertebrae, there were 136 sandwich vertebrae and 286 ordinary adjacent vertebrae. The refracture rate of sandwich vertebrae was 11.3% which was higher than that of ordinary adjacent vertebrae (6.3%)( χ ²=4.668, P=0.031). The 1- and 5-year fracture-free probabilities were 0.90 and 0.87 for the sandwich vertebrae, and 0.95 and 0.93 for the ordinary adjacent vertebrae, respectively. There was a significant difference between the two risk curves of refracture ( χ ²=4.823, P=0.028). Cox's proportional hazards regression model analysis results showed that the sandwich vertebrae, thoracolumbar location, the number of the augmented vertebrae, and the unilateral puncture were significant risk factors for refracture ( P<0.05).

Conclusion

The sandwich vertebrae has a higher risk of refracture when compared with the ordinary adjacent vertebrae, and its 1- and 5-year fracture-free probabilities are lower than those of the ordinary adjacent vertebrae. However, the 5-year fracture-free probability of sandwich vertebrae is still 0.87, so prophylactic enhancement is not recommended for all sandwich vertebrae. In addition, the sandwich vertebrae, thoracolumbar location, the number of the augmented vertebrae, and the unilateral puncture were important risk factors for refracture.

Correlation of Sagittal Imbalance and Recollapse after Percutaneous Vertebroplasty for Thoracolumbar Osteoporotic Vertebral Compression Fracture: A Multivariate Study of Risk Factors

Study Design

A retrospective case control study.

Purpose

This study aimed to assess the clinical significance of sagittal balance for predicting and managing the recollapse of cemented vertebra following percutaneous vertebroplasty (PVP) in patients with thoracolumbar osteoporotic vertebral fracture (OVF).

Overview of Literature

Recently, the recollapse of cemented vertebra following PVP for OVF has been reported. Although the risk factors for recollapse have been determined, the association between sagittal spinopelvic parameters and sagittal imbalance with recollapse has not been established.

Methods

Ambulatory patients who underwent single-level PVP for thoracolumbar OVF with a follow-up of at least 24 months were retrospectively reviewed. The patients were divided into two groups depending on the presence of symptomatic recollapse at the cemented vertebra: (1) recollapsed (RC) group and (2) noncollapsed (NC) group. The patient characteristics and radiographic measurements associated with sagittal imbalance were analyzed at each follow-up visit.

Results

Overall, 134 patients (RC group, n=28; NC group, n=106) were enrolled. The mean fracture-free interval was 3.2 months (range, 1.2–25.1 months). The multivariate binary logistic regression analysis identified low bone mineral density (p=0.047), degree of dynamic mobility within the vertebra (p=0.025), and sagittal imbalance as significant risk factors for recollapse (p=0.013; odds ratio, 5.405). The progression of sagittal imbalance and thoracolumbar kyphosis (T10–L2) was more significant in the RC and sagittal imbalance groups than in the NC group (both p=0.000).

Conclusions

Sagittal imbalance, lower bone mineral density, and dynamic mobility within the vertebra are associated with the recollapse of cemented vertebrae following PVP. Sagittal imbalance, rather than local kyphosis or thoracolumbar kyphosis, is particularly significant in that it results in more progressive collapse and sagittal deformity and is accompanied by substantial back pain and neurological deficits. Therefore, a stricter and more active management, including anti-osteoporosis medication, is required for the treatment of OVF with sagittal imbalance of the spine.

A Retrospective Analysis in 1347 Patients Undergoing Cement Augmentation for Osteoporotic Vertebral Compression Fracture: Is the Sandwich Vertebra at a Higher Risk of Further Fracture?

BACKGROUND

Multiple percutaneous vertebral cement augmentation may create sandwich vertebrae. Whether the sandwich vertebra is at higher risk of further fracture remains unknown.

OBJECTIVE

To compare the incidence of further fractures of sandwich vertebrae and adjacent vertebrae and to identify potential risk factors for sandwich vertebral fractures.

METHODS

Patients who underwent cement augmentation for osteoporotic vertebral compression fractures (OVCFs) in a single medical center between January 2012 and December 2015 were included. A sandwich vertebra was defined as an intact vertebra located between 2 previously cemented vertebrae. Demographic data and imaging findings were recorded. All patients were followed up for at least 24 mo postoperatively. During follow-up period, if the patient reported new-onset back pain with corresponding imaging findings, a diagnosis of sandwich vertebral fracture was made.

RESULTS

Among the 1347 patients who underwent vertebroplasty/kyphoplasty for OVCFs, 127 patients with 128 fracture levels met the criteria for sandwich vertebrae (females/males 100/27, mean age 77.8 ± 7.7 yr old). The fracture location was most common in the thoraco-lumbar junction (T10-L2), 68.5% (87/127). The incidence of sandwich vertebral fracture was 21.3%, whereas the incidence of adjacent level fracture of those with no sandwich vertebra was 16.4% (196/1194), P = .1879.

CONCLUSION

The incidence of sandwich vertebral fracture is not higher than that at the adjacent levels. The factor associated with further sandwich vertebral fracture was male gender. Once sandwich vertebral fracture occurred, patients may seek more surgical intervention than those with only adjacent fractures.

Fracture-free probability and predictors of new symptomatic fractures in sandwich, ordinary-adjacent, and non-adjacent vertebrae: a vertebra-specific survival analysis

BACKGROUND

It is unclear whether the sandwich vertebra, is at higher risk of new symptomatic fractures (NSFs), and whether prophylactic augmentation might benefit patients with sandwich vertebrae.

OBJECTIVE

To compare fracture-free probabilities of sandwich, ordinary-adjacent, and non-adjacent vertebrae, and identify predictors of NSFs.

METHODS

Data were retrospectively analyzed for patients who had undergone vertebral augmentation resulting in sandwich vertebrae. NSF rates were determined and predictors were identified using Cox proportional hazard models.

RESULTS

The analysis included 1408 untreated vertebrae (147 sandwich, 307 ordinary-adjacent, 954 non-adjacent vertebrae) in 125 patients. NSFs involved 19 sandwich, 19 ordinary-adjacent, and 16 non-adjacent vertebrae. The NSF rate was significantly higher in the patients with sandwich vertebrae (27.2%) than among all patients (14.8%). At the vertebra-specific level, the NSFs rate was 12.9% for sandwich vertebrae, significantly higher than 6.2% for ordinary-adjacent and 1.7% for non-adjacent vertebrae. The corresponding fracture-free probabilities of sandwich, ordinary-adjacent, and non-adjacent vertebrae were 0.89, 0.95, and 0.99 at 1 year, and 0.85, 0.92, and 0.98 at 5 years (p<0.05). Cox modeling identified the following as predictors for occurrence of an NSF in a given vertebra: vertebra location, type of vertebrae, number of augmented vertebrae, and puncture method.

CONCLUSION

Sandwich vertebrae are at higher risk of NSFs than ordinary-adjacent and non-adjacent vertebrae, and several NSF risk factors were identified. Since 85% of sandwich vertebrae are fracture-free for 5 years and NSF risk increases with the number of augmented vertebrae, prophylactic augmentation of every sandwich vertebra may be unnecessary.

[Risk factors analysis of adjacent fractures after percutaneous vertebroplasty for osteoporotic vertebral compression fracture]

Objective

To investigate the risk factors of adjacent fractures after percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fracture (OVCF).

Methods

A total of 2 216 patients who received PVP due to symptomatic OVCF between January 2014 and January 2017 and met the selection criteria were selected as study subjects. The clinical data was collected, including gender, age, height, body mass, history of smoking and drinking, whether the combination of hypertension, diabetes, coronary arteriosclerosis, chronic obstructive pulmonary disease (COPD), bone mineral density, the number of fractured vertebrae, the amount of cement injected into single vertebra, the cement leakage, and whether regular exercise after operation, whether regular anti-osteoporosis treatment after operation. Firstly, single factor analysis was performed on the observed indicators to preliminarily screen the influencing factors of adjacent fractures after PVP. Then, logistic regression analysis was carried out for relevant indicators with statistical significance to screen risk factors.

Results

All patients were followed up 12-24 months, with an average of 15.8 months. Among them, 227 patients (10.24%) had adjacent fractures. The univariate analysis showed that there were significant differences between the fracture group and non-fracture group in age, gender, preoperative bone density, history of smoking and drinking, COPD, the number of fractured vertebrae and the amount of bone cement injected into the single vertebra, as well as regular exercise after operation, regular anti-osteoporosis treatment after operation ( P<0.05). Further multivariate logistic regression analysis showed that the elderly and female, history of smoking, irregular exercise after operation, irregular anti-osteoporosis treatment after operation, low preoperative bone density, large number of fractured vertebrae, and small amount of bone cement injected into the single vertebra were risk factors for adjacent fractures after PVP in OVCF patients ( P<0.05).

Conclusion

The risk of adjacent fractures after PVP increases in elderly, female patients with low preoperative bone mineral density, large number of fractured vertebrae, and insufficient bone cement injection. The patients need to quit smoking, regular exercise, and anti-osteoporosis treatment after PVP.

Comparison of targeted percutaneous vertebroplasty and traditional percutaneous vertebroplasty for the treatment of osteoporotic vertebral compression fractures in the elderly

Objective

To investigate the clinical effect of precise puncture and low-dose bone cement in percutaneous vertebroplasty (PVP).

Methods

Sixty patients with osteoporotic vertebral compression fracture (OVCFs) who were treated with PVP in our hospital from July 2018 to June 2019. These included patients were divided into group A (N = 30) and group B (N = 30). Group A has punctured to the fracture area accurately and injected with a small dose of bone cement, the group B was injected with a conventional dose of bone cement. The operation time, the amount of bone cement injection, the number of X-rays, the VAS scores, the leakage rate of bone cement, and the incidence of adjacent vertebral fractures were compared between the two groups.

Result

The operation time, fluoroscopic times, and bone cement volume in group A are less than that in group B (P < 0.05). Patients in group A had a lower incidence of cement leakage and adjacent vertebral fracture than that in patients in group B. There was no significant difference in postoperative pain relief between the two groups.

Conclusions

Precise puncture and injection of small doses of bone cement can reduce the number of X-ray fluoroscopy, operation time, amount of bone cement injection, reduce the rate of bone cement leakage and the incidence of adjacent vertebral fractures, which is a safe and effective surgical approach for the treatment for the aged with OVCFs.

Bioactive poly (methyl methacrylate) bone cement for the treatment of osteoporotic vertebral compression fractures

Rationale: Poly (methyl methacrylate) (PMMA) bone cement is one of the most commonly used biomaterials for augmenting/stabilizing osteoporosis-induced vertebral compression fractures (OVCFs), such as percutaneous vertebroplasty (PVP) and balloon kyphoplasty (BKP). However, its clinical applications are limited by its poor performance in high compressive modulus and weak bonding to bone. To address these issues, a bioactive composite bone cement was developed for the treatment of osteoporotic vertebral compression fractures, in which mineralized collagen (MC) was incorporated into the PMMA bone cement (MC-PMMA). Methods: The in vitro properties of PMMA and MC-PMMA composite bone cement were determined, including setting time, compressive modulus, adherence, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells. The in vivo properties of both cements were evaluated in an animal study (36 osteoporotic New Zealand female rabbits divided equally between the two bone cement groups; PVP at L5) and a small-scale and short-term clinical study (12 patients in each of the two bone cement groups; follow-up: 2 years). Results: In terms of value for PMMA bone cement, the handling properties of MC-PMMA bone cement were not significantly different. However, both compressive strength and compressive modulus were found to be significantly lower. In the rabbit model study, at 8 and 12 weeks post-surgery, bone regeneration was more significant in MC-PMMA bone cement (cortical bone thickness, osteoblast area, new bone area, and bone ingrowth %; each significantly higher). In the clinical study, at a follow-up of 2 years, both the Visual Analogue Score and Oswestry Disability Index were significantly reduced when MC-PMMA cement was used. Conclusions: MC-PMMA bone cement demonstrated good adaptive mechanical properties and biocompatibility and may be a promising alternative to commercial PMMA bone cements for the treatment of osteoporotic vertebral fractures in clinical settings. While the present results for MC-PMMA bone cement are encouraging, further study of this cement is needed to explore its viability as an ideal alternative for use in PVP and BKP.

Poly(methyl methacrylate) bone cement composited with mineralized collagen for osteoporotic vertebral compression fractures in extremely old patients

To examine the clinical effects of a new bone cement composed of poly(methyl methacrylate) (PMMA) and mineralized collagen (MC) compared with pure PMMA bone cement in treating osteoporotic vertebral compression fractures (OVCFs) in patients aged over 80. In all, 32 cases using pure PMMA bone cement and 31 cases using MC-modified PMMA (MC-PMMA) bone cement for OVCFs between June 2014 and March 2016 were screened as PMMA group and MC-PMMA group, respectively, with an average age of over 80. The operation duration, intraoperative blood loss, hospital stay, oswestry disability index (ODI), visual analogue scale (VAS), anterior vertebral height (AVH), intermediate vertebral height (IVH) and posterior vertebral height (PVH) of injured vertebrae, vertebral computed tomography value, re-fracture rate of adjacent vertebrae, correction rate of spinal kyphotic angle and wedge-shaped vertebra angle and surgical complications were compared between the two groups. In the early post-operative period, the VAS, ODI, AVH and IVH in MC-PMMA group were comparable to those in the traditional PMMA group. Moreover, the MC-PMMA group showed better effects compared with the PMMA group 12 months after surgery. Thus, this new bone cement has superior clinic effects in the long term.

Mineralized Collagen Modified Polymethyl Methacrylate Bone Cement for Osteoporotic Compression Vertebral Fracture at 1-Year Follow-up

STUDY DESIGN

Retrospective comparative study.

OBJECTIVE

This study aimed to compare the clinical effects and imaging features of polymethyl methacrylate (PMMA) bone cement with and without mineralized collagen (MC) in percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fractures (OVCFs).

SUMMARY OF BACKGROUND DATA

PKP with PMMA is widely performed for OVCF. However, numerous complications have also been reported about the PMMA bone cement. Moreover, PMMA bone cement with and without MC have not been compared with respect to their postoperative efficacy and long-term follow-up.

METHODS

From July 2016 to July 2017, 105 OVCF patients were randomly divided into two groups based on their PKP treatment: MC-PMMA group and PMMA group. Clinical operation, cement leakage, Oswestry Disability Index, visual analog scale, height of the fractured vertebrae, Cobb angle, refracture of the adjacent vertebra, recompression, and computed tomography values of the injured vertebra were compared between the two groups postoperatively and after 1-year follow-up.

RESULTS

Clinical operation showed no differences between the two groups. Visual analog scale scores, Oswestry Disability Index scores, and Cobb angles showed statistically significant differences between the two groups after 1-year follow-up. The height of the vertebral body showed significant difference at 3 days postoperatively and preoperatively in each group and significant difference after 1 year between the two groups. The rate of refracture and leakage of the MC-PMMA group was lower than that of the PMMA group. The computed tomography value of the MC-PMMA group was obviously higher than that of the PMMA group after 1-year follow-up.

CONCLUSION

MC-modified PMMA did not change the beneficial properties of PMMA. This new bone cement has better biocompatibility, can form a stable structure in the vertebral body, and improve the prognosis of patients by reducing pain and reoperation.

LEVEL OF EVIDENCE

3.

Re-expansion of Osteoporotic Compression Fractures Using Bilateral SpineJack Implants: Early Clinical Experience and Biomechanical Considerations

Thoraco-lumbar osteoporotic compression fractures have a higher incidence of continued collapse with development of deformity and progression to vertebra plana when untreated and even after vertebral augmentation (VA) or balloon kyphoplasty (BKP). Even when there is the restoration of height and improvement in angulation, multiple long-term follow-up series have repeatedly documented that over time, many patients lose the initial height correction and in a smaller group the vertebral body re-collapses leading to the development of progressive deformity with an increased risk for adjacent level fractures. At first, larger balloons and more cement were used to try and avoid these problems, but it did not reduce the risk of adjacent fractures. Several procedures were developed to place various types of intervertebral implants combined with bone cement to maintain the initial height correction. Initial studies with these implants showed a reduction in adjacent level fractures but the systems did not proceed to market. The SpineJack^R (SJ) system (Stryker Corp, Kalamazoo, MI), consisting of bilateral expandable titanium implants supplemented with bone cement, was first used approximately 10 years ago in Europe and recently gained FDA approval in the United States. This system provides more symmetric and balanced lateral and anterior support and is effective with lesser amounts of bone cement compared to BKP. Follow-up studies have documented that there is equal or better pain control, with better long-term results based both on maintaining vertebral height restoration and deformity correction. Most importantly, statistically it clearly reduces the risk of adjacent level fractures by at least 60%. The biomechanical effects of intravertebral implants for osteoporotic fractures in regard to the risk of adjacent level fractures and preliminary experience with the use of the SJ is reviewed.