Authors: Ningxue Sun, Yuntao Chu, Zhibo Ge, Yang Liu
Categories: Review, Percutaneous kyphoplasty, Osteoporotic vertebral compression fractures, Bone cement injection volume
Source: European Journal of Medical Research
Authors: Ningxue Sun, Yuntao Chu, Zhibo Ge, Yang Liu
Osteoporosis is a prevalent bone disorder marked by a decrease in bone density and a deterioration of bone structure, leading to an increased risk of fractures due to weakened bone strength. As the global population ages, osteoporosis has become a significant public health issue, particularly among postmenopausal women who experience a rapid loss of bone density as a result of decreased estrogen levels. A common and disabling consequence of osteoporosis is osteoporotic vertebral compression fractures (OVCF), which can occur even with minimal trauma and often lead to pain, spinal deformities, and a diminished quality of life. Although conservative treatments, including medication and physical therapy, may provide some symptom relief, they are often insufficient for patients with severe fractures.
Percutaneous vertebral augmentation (PVA) has emerged as a promising minimally invasive surgical option for treating OVCF. The procedure involves percutaneously inserting a balloon into the fractured vertebra, inflating it to restore vertebral height and stability, and injecting bone cement to stabilize the vertebra and reduce pain. Compared to traditional surgical methods, PVA offers notable advantages, including shorter operative times, fewer complications, and faster recovery.
This review examines the indications for and technical aspects of PVA, while also assessing the clinical effectiveness of this treatment in managing OVCF. Despite its advantages, challenges remain, such as the potential for postoperative complications and the necessity of personalized treatment approaches. The aim of this review is to provide a thorough understanding of PVA as a valuable therapeutic option for OVCF, emphasizing recent developments and identifying areas for future research.
Osteoporosis is a common condition among older adults globally, and its prevalence continues to rise as populations age. Osteoporotic vertebral compression fractures (OVCF), one of the most frequent complications of osteoporosis, not only greatly diminish patients' quality of life but also can result in spinal deformities, chronic pain, and impaired function. While pharmacological and physical treatments have brought some improvement in managing the disease, traditional surgical options often carry considerable risks and challenges, particularly in cases of severe fractures. Percutaneous vertebral augmentation (PVA), a minimally invasive procedure, involves the percutaneous insertion of a balloon or support device into the fractured vertebra, which is then inflated to restore vertebral alignment, followed by the injection of bone cement. PVA includes percutaneous vertebroplasty (PVP), percutaneous kyphoplasty (PKP), percutaneous curved kyphoplasty (PCKP), bone filling mesh containers (BFMCs), Opti Mesh vertebral repair system, vertebral cage system (VBS), and scaffold screw-assisted internal fixation (SAIF). This technique has become an effective treatment for OVCF, offering pain relief and restoring spinal stability and morphology, making it particularly advantageous for elderly and high-risk patients.
As PVA techniques continue to evolve, clinical research increasingly demonstrates that PVA holds clear advantages over conventional surgical methods. However, challenges remain with its widespread application, including postoperative complications, long-term efficacy, and the need for individualized treatment approaches. This review aims to present a comprehensive summary of recent developments in PVA for the treatment of osteoporotic vertebral compression fractures, assessing its clinical outcomes, technological advancements, and risk management strategies, to provide valuable insights for clinical practice.
A comprehensive search of PubMed was conducted to identify relevant studies published between January 2000 and December 2024.
The following search terms were “Bone cement infusion ratio”, “Bone cement volume”, “Vertebral augmentation”, “Percutaneous vertebroplasty”, “Kyphoplasty”, “percutaneous curved kyphoplasty”, “bone filling mesh containers”, “Opti Mesh vertebral repair system”, “vertebral cage system”, “scaffold screw-assisted internal fixation”, “Osteoporotic vertebral compression fracture(s)”, “Clinical outcomes”, “Complications”.
Boolean operators (AND, OR) were used to combine these terms, and filters such as publication date, language (English only), and study type were applied to ensure relevance and quality. In addition, reference lists of included studies and relevant review articles were manually searched to identify additional studies that may have been missed in the initial database search.
Osteoporosis is a prevalent condition among the aging population worldwide. A study analyzing the global and regional prevalence rates and risk factors of osteoporosis, based on the diagnostic criteria set by the World Health Organization, reported global prevalence rates of 19.7% for osteoporosis and 40.4% for osteopenia [1]. Postmenopausal women, in particular, experience a significant reduction in bone density due to decreased estrogen levels, which substantially elevates the risk of fractures. OVCF is primarily caused by the loss of bone density associated with osteoporosis, making vertebral bodies susceptible to compression fractures from minor trauma or normal daily activities. The weakened structure of the vertebrae makes them prone to deformation under even minimal stress, leading to spinal kyphosis and loss of height. These fractures are often asymptomatic and may occur without a clear traumatic event. In the early stages, patients may only experience mild discomfort or pain in the lower back, typically after a minor fall or excessive load. Because the symptoms of osteoporotic vertebral compression fractures can be subtle, many patients do not seek medical attention promptly, resulting in delayed diagnosis and treatment. Some individuals may simply experience mild back pain or limited mobility, leading them to overlook the possibility of a fracture. Clinically, diagnosis is usually made through imaging techniques such as X-rays, CT scans, or MRI. However, a global multicenter study revealed that the missed diagnosis rate for vertebral fractures in postmenopausal women aged 65–80 years could be as high as 34% [2]. The combination of low consultation rates and high misdiagnosis rates often means that patients only seek examination when more severe symptoms, such as spinal deformities or nerve damage, emerge, thereby delaying the opportunity for timely treatment.
Traditional treatments for OVCF typically include pharmacological therapies (such as anti-osteoporotic medications) and conservative measures (such as bed rest and back support braces) [3]. However, these approaches have limitations in directly addressing the fracture itself and often provide insufficient relief in terms of restoring spinal stability and alleviating pain post-injury. For patients with severe fractures, surgical intervention, such as open vertebroplasty, may be required. However, these procedures are associated with larger incisions, longer recovery times, higher financial costs, and inherent surgical risks. In elderly patients, who often have multiple comorbidities such as cardiovascular diseases and diabetes, the risks associated with surgery are further heightened. The incidence of OVCF is particularly high in older individuals, but due to their frail health, many conventional treatment options are not feasible, leading to suboptimal therapeutic outcomes.
PVA has emerged as a highly effective, minimally invasive surgical option. The procedure is performed through a small incision and does not require open surgery, thus minimizing trauma, reducing blood loss, shortening hospitalization, and allowing for a faster recovery. PVA has demonstrated significant improvements in both the quality of life and clinical symptoms of patients.
Indications: PVA is indicated for patients with severe pain who have not responded to non-surgical treatments; those with non-healing vertebral fractures or fractures complicated by cystic degeneration or necrosis of the vertebrae; patients who are unable to remain in bed for prolonged periods; and elderly patients, in whom early surgical intervention can help reduce bed rest duration and decrease the occurrence of fracture-related complications [4].
Absolute Contraindications: PVA is contraindicated in individuals who cannot tolerate surgery, as well as in cases of painless, chronic OVCF. It is also not recommended for patients with local infection at the surgical site or uncontrolled systemic infections, those with severe coagulopathy, or patients who are allergic to bone cement materials. It is crucial to note that prophylactic augmentation should not be performed on vertebrae that have not been fractured, including adjacent vertebrae to the fracture site or those that have already been reinforced with bone cement.
Relative Contraindications: PVA should be avoided in cases of severe vertebral compression fractures with bone fragments in the spinal canal, in patients with a tendency to bleed, in individuals with active infections elsewhere in the body, and in those with radicular pain caused by nerve compression unrelated to the vertebral fracture.
PVA puncture techniques are typically categorized into unilateral and bilateral approaches, each with distinct advantages and limitations. Studies have shown that the unilateral approach achieves comparable short-term outcomes in terms of fracture reduction, pain relief, and functional improvement compared to the bilateral approach. A clinical study involving 147 patients with osteoporotic vertebral compression fractures (OVCF) found that the unilateral group had significantly shorter operation times (41.60 ± 5.64 min vs. 66.53 ± 9.40 min) and lower bone cement volume (5.27 ± 0.73 mL vs. 6.87 ± 0.93 mL) (P < 0.01). The unilateral approach offers benefits such as reduced fluoroscopy exposure, less blood loss, and minimized procedural trauma [5]. However, it may result in uneven cement distribution, with higher concentration on the punctured side, potentially leading to asymmetric compressive strength and increased risk of adjacent vertebral fractures [6]. To address this, directional cement delivery devices have been developed (Fig. 1), enabling controlled cement distribution and achieving outcomes similar to those of the bilateral approach [7].Fig. 1A Lateral view of the directional bone cement delivery device. B Frontal view of the directional bone cement delivery device. C Sleeve and plunger of the directional bone cement delivery device
Bilateral puncture and cement injection have been shown to improve the distribution of bone cement, leading to better results than the unilateral approach in restoring vertebral anterior height, enhancing the Cobb angle of kyphosis, and improving early VAS scores [8]. One advantage of the bilateral approach is that the smaller angle of the puncture needle reduces the likelihood of damaging the spinal cord and nerve roots. In contrast, the unilateral approach requires a greater needle angle to push the cement across the midline, which increases the risk of injury to the spinal cord and nerve roots, potentially resulting in pedicle fractures (Fig. 2). However, the bilateral puncture approach has several disadvantages, including longer operative times, more fluoroscopy sessions, higher cement injection volumes, and an elevated risk of cement leakage.Fig. 2A Lateral view of the bilateral approach. B Posterior view of the bilateral approach
The transcostal-pedicular approach, an evolution of the traditional pedicular technique, involves a more lateral puncture site and a greater inward needle angle. The puncture is typically made at the base of the transverse process, allowing the needle to cross the vertebral midline and promoting more uniform bone cement distribution. Studies have shown that this approach achieves comparable short-term outcomes in fracture reduction, pain relief, and functional improvement compared to the bilateral approach. Although cement distribution may be slightly less even than with the bilateral technique, it offers advantages such as shorter surgical time and reduced fluoroscopy exposure [9].
The posterior superior vertebral approach is particularly useful when the pedicle is narrow or has a small outward angle. In this method, the needle is inserted at a 30–35° angle, with the tip positioned at the lateral edge of the vertebral body on anteroposterior X-rays and at the posterior upper corner on lateral views. This approach enables more balanced cement distribution, reduces surgical and fluoroscopy time, and lowers the risk of cement leakage. It provides clinical outcomes similar to those of the bilateral approach in terms of vertebral restoration and functional improvement.
For osteoporotic vertebral compression fractures at L4 or L5, Huang et al. introduced the “O” point puncture technique, a modified unilateral extrapedicular approach [10]. The entry point is located at the intersection of the transverse process base, the posterior superior corner of the pedicle, and the lateral edge of the superior articular process. This method has been shown to improve pain relief, reduce surgical and fluoroscopy time, enhance vertebral reconstruction, and achieve better cement distribution compared to conventional bilateral techniques. Preoperative 3D CT planning combined with intraoperative 3D-printed guides, skin markers, and angle-measuring devices enhances precision and further reduces procedural time and radiation exposure [11].
The choice of puncture approach should be individualized based on the patient’s condition, including fracture severity, age, and overall health. For isolated fractures, a unilateral approach is usually sufficient. However, for complex or multi-level fractures, a bilateral approach may offer better cement distribution. In elderly patients or those with significant comorbidities, the unilateral approach is often preferred due to its less invasive nature and lower complication risk. While the unilateral approach generally allows for faster surgery and recovery, the bilateral approach may be more suitable for cases requiring balanced cement distribution.
Osteoporotic vertebral compression fractures (OVCF) are commonly treated with PVP, a minimally invasive procedure that offers rapid recovery and proven efficacy. Under general or local anesthesia, guided by C-arm fluoroscopy, a 5-mm skin incision is made, and a needle is inserted into the fractured vertebra. Bone cement is then injected to restore vertebral biomechanical properties (Fig. 3). Studies indicate that restoring vertebral strength helps prevent further compression, while enhancing stiffness stabilizes the vertebra, alleviates pain, and supports fracture healing [12]. PVP also provides pain relief through the exothermic reaction and toxic effects of bone cement polymerization, which destroy nerve endings and inflammatory mediators, alter the vertebral microenvironment, reduce pain sensitivity, and inhibit pain mediator production [13].Fig. 3A Schematic diagram of PVP. B Schematic diagram of PKP
PKP involves inserting a balloon through the vertebral pedicles into the vertebral body (Fig. 3). The balloon is inflated to reduce compression deformity and restore vertebral height. After balloon removal, bone cement is injected to stabilize the fracture and relieve pain. This technique effectively restores vertebral morphology, stabilizes the injury, and alleviates symptoms. Studies indicate that PKP for OVCF reduces postoperative cement leakage risk, achieves better vertebral height restoration, and is particularly effective for osteoporosis-related fractures [14].
Percutaneous curved kyphoplasty (PCKP) commonly employs a unilateral puncture technique, in which a curved bone drill is used to create a channel from the pedicle to the contralateral side of the vertebral body. This facilitates the even distribution of bone cement across the midline (Fig. 4) [15]. A systematic review and meta-analysis involving 562 patients and 593 affected vertebrae demonstrated that the curved technique offers several advantages over the non-curved approach, including reduced tissue trauma, shorter operative time (MD = − 8.60; 95% CI − 13.75 to − 3.45) (p = 0.001), decreased cement injection volume (MD = − 0.82; 95% CI − 1.50 to − 0.14) (p = 0.02), fewer fluoroscopic exposures (SMD = − 1.22; 95% CI − 1.84 to − 0.60) (p = 0.0001), more uniform bilateral cement distribution, and a lower risk of cement leakage (OR = 0.40; 95% CI 0.27–0.60) (< 0.0001) [16]. The enhanced cement distribution contributes to a more stable biomechanical structure, thereby reducing the risk of subsequent fractures in both the treated and adjacent vertebrae.Fig. 4A Percutaneous curved kyphoplasty (PCKP) balloon device. B CT axial image showing PCKP access into the vertebral body through the created channel. C CT axial image of balloon inflation during PCKP. This image is from Wang C, Zhang Y, Chen W, Yan SL, Guo KJ, Feng S. Comparison of percutaneous curved kyphoplasty and bilateral percutaneous kyphoplasty in osteoporotic vertebral compression a randomized controlled trial. BMC Musculoskelet Disord. 2021;22(1):588
Bone-filling mesh containers (BFMCs) employ a mesh-like structure composed of biocompatible, high-strength metal wires. Initially cylindrical, the mesh can be inserted percutaneously into the vertebral body. During cement injection, it functions similarly to a balloon, allowing even distribution of bone cement through its openings and reducing the risk of leakage. If excessive expansion or leakage occurs, cement infusion should be stopped, and the device removed after the cement has hardened. A randomized controlled trial compared 80 patients divided into two 40 in the PKP group (Group A) and 40 in the BFMCs group (Group B). The average cement leakage rate was 0.225 in Group A and 0 in Group B (P = 0.034, F = 7.500) [17]. Studies have shown that BFMCs effectively relieve pain, correct the Cobb angle, and reduce cement leakage [18]. However, during placement, some mesh openings may be damaged by sharp cancellous bone spicules, or improper positioning may lead to leakage.
Opti Mesh is an elastic mesh device that is percutaneously inserted and expanded within the affected vertebra. Once deployed, it holds an allograft bone within its mesh openings, promoting vertebral height restoration, spinal alignment correction, and pain relief (Fig. 5). A key advantage is its ability to control bone graft delivery, enabling new bone and vascular tissue ingrowth [19]. However, long-term studies are lacking to confirm the durability of vertebral height restoration.The system has several limitations. It requires a large-diameter working channel for implantation, often necessitating a transpedicular approach, which may increase the risk of adjacent tissue damage [20].Fig. 5A The system consists of a detachable polyethylene mesh balloon and a delivery catheter. B An expandable shapeformer is inserted to create a cavity within the vertebra. C A mesh bag filled with allograft bone is delivered using multi-cylindrical forceps and detached once satisfactory endplate height restoration is achieved. This image is from Inamasu J, Guiot BH, Uribe JS. Flexion-distraction injury of the L1 vertebra treated with short-segment posterior fixation and Optimesh. J Clin Neurosci. 2008;15(2):214–218
Vertebral body stenting system (VBS) is an effective technique for restoring vertebral height and minimizing postoperative height loss [21]. During the procedure, a titanium alloy stent is mounted on an inflatable balloon and inserted into the vertebral body. Balloon inflation causes the stent to expand, correcting the wedge deformity and providing structural support to the compressed endplates (Fig. 6) [22]. While some studies suggest that VBS reduces the risk of cement leakage compared to percutaneous kyphoplasty (PKP) [23, 24], others, including findings by Werner et al., report no significant difference in leakage prevention [25]. Cement leakage is most commonly observed anteriorly, potentially due to restricted cement dispersion caused by the stent’s mesh structure. Greater stent expansion generally correlates with reduced obstruction and more uniform cement distribution.Fig. 6A Postoperative X-ray lateral view of VBS. B Postoperative X-ray orthopantomogram of VBS. C Schematic diagram of VAS surgical balloon and titanium mesh expansion
Nonetheless, VBS demonstrates superior outcomes compared to traditional PKP in terms of vertebral height restoration, kyphosis correction [26–28], and reduced risk of postoperative vertebral collapse [29]. It is particularly recommended for cases involving vertebral height loss exceeding 35% or a Cobb angle greater than 15°, especially in severe compression fractures [30]. A limitation of the titanium stent, however, is its limited deformability, which may lead to uneven pressure distribution during balloon inflation and increase the risk of balloon rupture in high-pressure zones.
Cianfoni et al. developed the stent-screw-assisted internal fixation (SAIF) technique for the treatment of severe osteoporotic vertebral fractures based on VBS (Fig. 7) [31]. Under fluoroscopic guidance, stents are inserted bilaterally through the pedicles into the vertebral body. After expansion, screws are placed through a pedicle window into the stents, and bone cement is injected via the porous screws. The stent’s mesh structure disperses the cement, forming a stable bridge between the two VBSs. The screws anchor the cement-stent complex, reducing the risk of displacement while stabilizing the vertebral column. SAIF offers two key (1) the expanded stent maintains axial load-bearing capacity after balloon deflation, (2) it helps contain cement along the vertebral cortex, improving cement distribution. Studies have shown that SAIF provides better biomechanical stability than traditional PKP, thereby reducing the risk of postoperative re-fracture [32].Fig. 7A This figure shows SAIF implants within a lumbar vertebra, with bilateral vertebral body stents deployed and expanded. Transpedicular fenestrated screws are inserted into the stent lumens. The cement injection process via an injection cannula (arrowhead) is not shown to improve implant visibility. B–D Key procedural steps of SAIF, guided by fluoroscopy before cement injection, are illustrated. E The main instruments for SAIF a 7G trocar, manual coaxial drill, balloon-mounted stent, k-wire, screwdriver-mounted screw over a k-wire, and a 14G luer lock cement injection cannula placed within the screw. F A schematic diagram illustrates how a fitting cannula (blue) aligns with the screw stem, allowing cement (white) to flow through the screw fenestrations and fill the stent lumen. This image is from Cianfoni A, Distefano D, Isalberti M, et al. Stent-screw-assisted internal the SAIF technique to augment severe osteoporotic and neoplastic vertebral body fractures. J Neurointerv Surg. 2019;11(6):603–609
Although existing literature has extensively evaluated the efficacy of PVA, key controversies and evidence gaps still hinder its clinical application. First, there is significant variability in reported bone cement leakage rates between PKP and PVP. While some studies suggest that PKP reduces leakage risk (OR 0.40–0.60), others, such as Werner et al. [25], report no statistically significant difference, possibly due to variations in surgeon experience or inconsistent definitions of leakage (e.g., inclusion of asymptomatic radiographic leakage). New techniques like PCKP (arc drilling) and BFMCs (mesh bag confinement) have shown lower leakage rates, but their results are based on small sample sizes, and the claim of “zero leakage” for BFMCs requires validation in larger studies [17]. VBS and SAIF improve cement distribution through scaffolds or screw fixation, but uneven scaffold expansion may lead to anterior or posterior leakage, and their benefits need confirmation through prospective controlled trials.
The clinical relevance of vertebral height restoration remains debated. Although VBS and SAIF demonstrate better height restoration than PKP in severe compression fractures (> 35% loss), overcorrection may increase the risk of endplate damage, and evidence linking height restoration to functional outcomes (e.g., ODI scores) is limited [30]. Biological technologies like Opti Mesh theoretically enhance osseointegration, but long-term follow-up data are lacking to confirm their effectiveness in maintaining height.
Additionally, biomechanical studies are largely based on cadaveric models and do not reflect the dynamic conditions of osteoporotic patients. While SAIF enhances central column stability via a “scaffold-screw” system, clinical evidence supporting its ability to reduce adjacent vertebral fractures is insufficient. The uniform cement distribution in BFMCs may compromise local mechanical strength, whereas the high-density cement clusters in PKP may be more suitable for high-load areas. The technical features and clinical considerations of various procedures are summarized in Table 1. Table 1Comparative analysis of vertebral augmentation technical characteristics and clinical considerationsSurgical methodRecommended casesAdvantagesDisadvantagesPVPPatients with relatively intact lateral cortical bone and low degree of vertebral compressionMinimally invasive, effectively relieves pain, stabilizes vertebraeHigh risk of bone cement leakage, no fracture reductionPKPPatients with severe vertebral collapse but intact posterior walls who require restoration of vertebral heightReduce the risk of cement leakage, restore vertebral height, and reduce spinal kyphosisMore invasive than PVP, longer surgery time, higher cost, and limited restoration of vertebral heightPCKPPrioritize patients who prefer minimally invasive procedures and shorter surgery timesSingle-sided puncture reduces surgery time and ensures uniform arc-shaped cement distribution to achieve biomechanical stabilityTechnical complexity, potential learning curve, and limited long-term dataBFMCFor patients with vertebral fractures at high risk of bone cement leakage and Cobb angle correctionThe expandable biocompatible mesh bag design restores vertebral height while reducing tissue reaction, and the mesh bag structure guides the uniform distribution of bone cementThe equipment is expensive and the learning curve is steepOpti mesh vertebral repair systemCases seeking biological fusion (such as young patients)Promoting bio-osseous integrationIncreased risk of tissue damage, high technical demands on the surgeon, and lack of long-term follow-up dataVBSSevere vertebral compression fracture (height loss > 35% or Cobb angle > 15°)Titanium alloy stents provide mechanical support and reduce the risk of postoperative vertebral collapse, making them particularly suitable for severe compression fracturesTitanium alloy stents hinder bone cement diffusion and are relatively expensiveSAIFComplex fractures requiring simultaneous reinforcement of the pedicle and vertebral body, high-risk patients with central column instabilityThe double-sided bracket and screw design provides excellent biomechanical stabilityThe surgery is highly invasive, the equipment is expensive, the learning curve is steep, and long-term clinical data is limitedPVP percutaneous vertebroplasty, PKP percutaneous kyphoplasty, PCKP percutaneous curved kyphoplasty, BFMCs bone filling mesh containers, VBS vertebral cage system, SAIF scaffold screw-assisted internal fixation
Polymethyl methacrylate (PMMA) is a synthetic polymer typically composed of a mixture of PMMA powder and methyl methacrylate monomers. Upon addition of an initiator, PMMA cures rapidly in vivo, offering advantages such as high moldability, good biocompatibility, and chemical stability. It is easy to handle and can be prepared at the surgical site. However, PMMA does not form a chemical bond with bone tissue, and the heat generated during polymerization, along with the cytotoxicity of the monomer, limits its clinical use [33].
Calcium phosphate cement (CPC) is a biodegradable bone cement that is gradually absorbed and replaced by bone tissue, making it a suitable material for bone repair. Its primary components are calcium phosphate salts, such as calcium hydrogen phosphate and calcium triphosphate. During hydration, CPC forms a crystalline structure similar to natural bone minerals and exhibits good biocompatibility, enabling it to bond with bone tissue and promote healing [34]. Compared to PMMA, CPC has lower mechanical strength and is therefore more appropriate for small bone defects rather than load-bearing applications. The application of CPC is relatively complex, requiring careful control of the hydration process to prevent premature or delayed setting. While its degradation properties support bone regeneration, the rate of degradation can vary depending on factors such as defect size, location, and the in vivo environment. Thus, an inappropriate degradation rate may negatively affect the healing outcome.
PMMA-CPC hybrid bone cement is formed by incorporating CPC, which exhibits good biocompatibility, into PMMA. This composite material enhances the biological activity of PMMA, improves the mechanical strength and rigidity of vertebral bodies, and reduces the heat generated during polymerization, thereby decreasing implant toxicity [35]. Its clay-like consistency helps minimize the risk of blood or venous leakage into the spinal canal and reduces the likelihood of cement leakage through fracture gaps. However, its clinical efficacy remains controversial, and further large-scale studies are needed to clarify its role in vertebral repair.
To overcome the limitations of traditional bone cements, researchers have developed improved formulations for better clinical performance. Wang et al. [36] compared PMMA bone cement modified with biomimetic mineralized collagen (MC) to conventional PMMA in the treatment of OVCF. The MC-modified cement showed comparable pain relief and vertebral height restoration, but significantly improved bone density and mechanical strength. In addition, functionalized graphene materials (FGMs) incorporated into PMMA enhance bioactivity by releasing biologically active cations and increasing alkaline phosphatase (ALP) activity by 2.9-fold compared to standard PMMA, thereby improving its osteogenic potential [37].
Lu et al. [38] developed a novel, biodegradable calcium phosphate-based nanocomposite (CPN) with improved anti-leakage properties. CPN demonstrated better penetration into cancellous bone and effective encapsulation of bone tissue. Moreover, incorporation of poly(lactide-co-glycolic acid) (PLGA) nanofibers into calcium phosphate cement (CPC) resulted in a porous, injectable cement with enhanced structural stability. The addition of carboxymethyl cellulose (CMC) improved injectability and resistance to washout. The controlled degradation of PLGA supports bone regeneration and vascular remodeling through sustained release of Ca^2^⁺ and lactate [39]. Although these studies were conducted in rat femoral condyle defect models, further research is required to evaluate their effectiveness in vertebral repair.
Although bioactive bone cement effectively alleviates pain in OVCF, complications such as PMMA leakage—leading to spinal cord compression or pulmonary embolism—remain critical concerns. To address these risks, PKP using polyethylene mesh capsules (Opti Mesh) with fragmented bone grafts has emerged as an alternative. Cancellous bone particles, a fully biological material, offer osteoinductive properties, promoting osteogenesis while providing substantial pain relief (Table 2). Table 2comparative analysis of spinal filling materials for vertebral advantages and limitationsSpinal filling materialsAdvantagesDisadvantagesPMMAHigh plasticity, fast curing, excellent biomechanical strength, easy to use, long-term chemical stability, widely clinically verifiedNo biological activity, heat generation during polymerization, monomer cytotoxicity, short operating time window, imaging artifactsCPCBiodegradability, bone conductivity, excellent biocompatibility, chemical bonding with bone tissue, imaging compatibilityLow mechanical strength, complex operation, uncontrollable degradation rate, long curing time, and high pricePMMA-CPC hybrid bone cementSynergistic enhancement effect, safety optimization, improved operational performance, imaging compatibilityInsufficient clinical evidence, increased costs, and uncertain degradation kineticsComposite bone cementMC: 18–25% increase in bone density (vs. traditional PMMA)FGMs: 2.9-fold increase in ALP activityCPN: 40% increase in bone tissue encapsulation ratePLGA-CPC Controlled degradation (sustained release of Ca^2^⁺/lactic acid)Currently limited to animal model validation, process complexityCancellous bone particlesFully biocompatible, promotes vertebral endplate regenerationPoor initial stability, uncertain osseointegrationPMMA Polymethyl Methacrylate, CPC Calcium Phosphate Cement, MC mineralized collagen, ALP alkaline phosphatase, CPN calcium phosphate-based nanocomposite, PLGA poly (lactide-co-glycolic acid)
Zhang et al. [40] compared cancellous bone particles and PMMA for OVCF treatment, finding that both restored vertebral strength and stiffness. However, cancellous bone demonstrated superior mechanical compatibility and biocompatibility, thereby avoiding the disadvantages of PMMA, including osteoconductive and osteoinductive activity, high polymerization temperature, monomer toxicity, and mismatch in elastic modulus post-curing [41, 42].
The volume of bone cement infused during vertebroplasty significantly affects surgical outcomes and patient safety. Insufficient infusion may lead to poor results, including chronic postoperative pain and vertebral collapse. Studies have shown that a volume greater than 4.5 ml, or as much as safely possible, is necessary for effective pain relief [43, 44]. Infusion volumes above 4 ml improve clinical outcomes and reduce the risk of vertebral collapse, while 6–8 ml may slightly enhance radiological findings. Many studies suggest that 4–7 ml of bone cement ensures good efficacy in treating OVCF [45, 46]. Biomechanical and finite element studies have been used to determine optimal cement volumes. Belkoff et al. [47] found that 2 ml of either Orthocomp or Simplex 20 restored structural integrity, but higher volumes were needed to restore stiffness—4 ml in the thoracic spine and 6 ml in the lumbar spine for Orthocomp, and 4 ml and 8 ml, respectively, for Simplex 20.There is no significant difference in the efficacy of bone cement between low viscosity and high viscosity [48].
However, the bone cement infusion volume is also positively correlated with cement leakage, and exceeding a certain infusion volume may increase the risk of cement leakage [49]. For low-viscosity cement, leakage increases significantly when the volume exceeds 6 ml, whereas high-viscosity cement shows less leakage at 6–8 ml. Therefore, the recommended volume is 4–6 ml for low-viscosity and 6–8 ml for high-viscosity cement [48]. Zhu et al. [50] suggested limiting infusion to less than 3.5 ml for thoracic segments and less than 4 ml for lumbar segments to minimize leakage. PCKP utilizes the curved design of the bone cement injector and balloon expansion support, making it safer, less invasive, and faster than traditional bilateral PKP. Although its short-term efficacy in treating OVCF is similar, it reduces the difficulty of puncture to some extent and facilitates the distribution of bone cement. [15, 51, 52]. However, there is limited research on the optimal cement volume for these newer techniques. The recommended volumes from the included studies are summarized in Table 3. Table 3Milliliters of bone cement infusionStudyReferenceType of studyNumber of patients (n)Vertebralbodies (n)Age (years)Gender (M/F)surgical approachbone cement brandbone cement infusion volume (ml)Belkoff et al. [47][25]Experimental study1214483.1 ± 5.3^1^0/12PVPOrthocomp or Simplex 206–8Kaufmann et al.[44][27]Retrospective study15815876 ^2^49/109PVPOrthocomp or Simplex 203.4Fu et al. [43][26]Retrospective study10810867.23 ± 9.15^1^65/43PVPOsteoPal-V or Spineplex6.9 ± 2.1Wang et al. [48][13]Retrospective study30730772.06 ± 8.44^1^72/235PVPMendec or Vertecem Vþ6–8Belkoff et al. [45][28]Experimental study42080 ± 5^1^0/4PVPOrthocomp or Simplex 20 < 8Martinčič et al. [46][29]Experimental study131377^3^9/4PVPconfidence Spinal Cement System4–6Zhu et al. [50][30]Retrospective study48580468.7^3^112/373PVPStryker Corporation3.471: mean ± SD2: Median3: meanM/F: Male/Female
Currently, bone cement infusion volume in PVA is often measured in milliliters. However, due to variations in vertebral size across different ethnicities, genders, and regions, expressing the volume as a ratio of cement to vertebral body volume—known as the bone cement infusion ratio—is more clinically meaningful (Fig. 8) [53]. Molloy et al. [54] used the Archimedean displacement method to measure the volume of 120 thoracolumbar vertebrae from osteoporotic female cadavers and simulated fractures to assess strength and stiffness. They found that restoring strength and stiffness required cement infusion ratios of 16.2% and 29.8%, respectively. Liebschner et al. [55] used finite element analysis to determine that approximately 15% cement volume could restore vertebral stiffness to pre-injury levels, while higher volumes may over-stiffen the vertebra (Fig. 9).Fig. 8A The cross-sectional area; B The height of the vertebra were measured near the level of the central point of the vertebra (the average height of the anterior, middle and posterior edges of the vertebra); It is concluded that vertebral body volume = vertebral cross-sectional area × vertebral body heightFig. 9Calculate the volume of vertebral body by Mimics software
However, biomechanical studies and finite element models often simplify fracture mechanisms, typically using axial compression, which may not reflect the complex, uncontrolled conditions seen in clinical practice [54]. Therefore, these findings should be interpreted with caution when applied to real-world scenarios. To address these limitations, retrospective clinical studies have explored optimal cement infusion ratios in PVP for OVCF. Jin et al. [56] reported that a cement infusion ratio exceeding 21% at T11–L1 increased the risk of pulmonary embolism, suggesting an optimal ratio of 11.65% for pain relief and safety. Nieuwenhuijse et al. [57] found that a 24% infusion ratio achieved 93–100% pain relief without increasing leakage or new fractures. Kwon et al. [58] identified an optimal ratio of 27.8% with 80% sensitivity and 87.5% specificity. Sun et al. [59] suggested a ratio of 19.78% for satisfactory distribution.
With advances in CT and 3D reconstruction technology, postoperative CT data can now be imported into software like Mimics to accurately calculate the actual cement volume and vertebral volume (Fig. 9), enabling precise determination of the infusion ratio. Gao et al. [60] used this approach in unilateral PVP and found that a 13.68% cement/vertebral body ratio effectively prevented leakage and complications. For bilateral PVP, Zhou et al. [61] recommended a ratio of 28.58% for optimal distribution.
Research on the appropriate cement infusion ratio for PKP remains limited. One study reported an average augmentation volume of 22.1% (range: 5.1–44.3%), with one outlier receiving 9 ml (56.3%) [62]. Sun et al. [53] analyzed 150 patients with GSQ grade 2 or lower OVCF and found that a 40–60% infusion ratio improved outcomes and reduced complications. The higher ratio in PKP may be attributed to the cavity created by balloon expansion, allowing for greater cement volume. More clinical trials are needed to refine these recommendations. For detailed information regarding the appropriate bone cement infusion ratio, please refer to Table 4. Table 4Bone cement filling ratioStudyReferenceType of studyNumber of patients (n)Vertebralbodies (n)Age (years)Gender (M/F)Surgical approachBone cement brandBone cement infusion ratio (%)Molloy et al. [54][39]Experimental study1012065–930/10PVPBosworth16.2(restoration of strength) 29.8(restoration of stiffness)Liebschner et al. [55][40]Experimental study1173^3^0/1PVPN/A15Jin et al. [56][41]Retrospective study969676.3^3^23/73PVPN/A11.65Nieuwenhuijse et al. [57][42]Retrospective study10619673.7^3^27/79PVPN/A24Kwon et al. [58][43]Retrospective study10910974.1 ± 10.3^1^23/86PVPN/A27.8Sun et al. [59][44]Prospective cohort study13013069.58^3^36/94PVPN/A19.78Gao et al. [60][3]Retrospective study48558572.89102/393PVPVia Andrea Doria13.68 (PSBCV/VCV%)Zhou et al.[61] [45]Retrospective study15015071.9150/100PVPN/A28.58Röder et al.[62][24]Retrospective study27627667.982/194PKPN/A22.1Sun et al. [53][38]Retrospective study15015071.8523/127PKPMendec40–601: mean ± SD3: meanN/A Not ApplicableM/F Male/FemalePSBCV/VCV% puncture-side bone cement/vertebral body volume ratio
In conclusion, with the gradual development of percutaneous vertebral augmentation (PVA) and the gradual maturation of filler materials, as well as the optimization of the appropriate cement infusion volume. The indications for surgery have been expanded, the risk of surgery has been reduced, the success rate of surgery has been improved, the duration of surgery has been shortened, and the occurrence of surgical complications has been reduced. With the advancement of science and technology, innovation of surgical techniques and in-depth clinical research, minimally invasive surgical treatment and precision treatment are the future development direction of spinal surgery.
Although percutaneous vertebral augmentation (PVA) has demonstrated significant results in relieving pain and restoring vertebral stability in patients with osteoporotic vertebral compression fractures (OVCF), several limitations remain. The procedure focuses on providing immediate pain relief and biomechanical support but does not address the underlying condition of osteoporosis, which increases the risk of future fractures. Additionally, complications such as cement leakage may occur, potentially leading to serious consequences like spinal cord compression or pulmonary embolism. Currently, there is a lack of stratified treatment guidelines based on fracture severity, bone density, and patient age, leading to unnecessary invasive treatments for mild OVCF.
Future studies should include multicenter RCTs with standardized assessment criteria (e.g., leakage classification, functional outcomes) combined with cost-effectiveness analyses to establish personalized treatment algorithms that optimize technical choices and maximize patient benefits.Advances in imaging technology and improvements in surgical techniques are expected to enhance the safety and efficacy of PVA, especially by reducing complications such as cement leakage. The development of biodegradable and biocompatible bone cements may further improve therapeutic outcomes, promote natural bone healing, and reduce the risks associated with long-term use of permanent bone cement. Furthermore, combining PVA with osteoporosis treatment may provide a more comprehensive approach, addressing both the fracture and the underlying bone loss. Ongoing research will play a critical role in optimizing these techniques, improving patient outcomes, and expanding the clinical applicability of PVA.