Minimally invasive surgical techniques for the treatment of thoracolumbar burst fractures

Abstract

Surgeons are often faced with complex decision-making when deciding on the optimum surgical management of thoracolumbar (TL) burst fractures. The magnitude of surgical techniques is vast from standard open techniques to minimally invasive surgery (MIS). In recent years, the application of MIS has grown in popularity in parallel to impressive technological advances. In this narrative review, we discuss the available literature focusing on minimally invasive surgical techniques for TL burst fractures. The aim of this article is to help guide spinal surgeons who wish to include MIS as part of their surgical portfolio and to identify remaining knowledge gaps. We aimed to present a review on the choice of long vs short construct, cement augmentation techniques, reduction and realignment techniques, surgical nuances in incomplete (A3) versus complete (A4) burst fractures, as well as discuss the role of implant removal. Percutaneous pedicle screw fixation including the index fracture level and subsequent implant removal has shown promise for the surgical treatment of TL AO Type A3 fractures, and A4 fractures. This technique may be best considered as internal bracing while fracture heals with the prototypical patient being a young active individual without severe kyphotic deformity. These techniques can be enhanced with cement augmentation as well as reduction and realignment techniques. With ongoing technological advancement, the armentarium of MIS surgical techniques applicable to TL burst fractures will certainly continue to expand. Despite rapid technological advances, a comprehensive understanding of optimal application of those techniques is lacking creating knowledge gaps.

Surgeons are often faced with complex decision-making when deciding on optimum surgical management of thoracolumbar (TL) burst fractures. Operative vs nonoperative management have both shown similar outcomes, but surgical management has been shown to be cost-effective.^1,2 The magnitude of surgical techniques is vast from standard open techniques to minimally invasive surgery (MIS) as well as circumferential approaches from anterior, lateral, posterior and combined anterolateral-posterior approaches. In recent years, the application of MIS has grown in popularity with an increasing spectrum of techniques applicable to TL burst fractures. This growth is occurring in parallel to rapid and impressive technological progress.

The fundamental principles of surgical treatment of fractures include anatomical reduction, neural decompression, reinforcement of the anterior column, stable fixation, reconstruction of the posterior tension band, and bony fusion when indicated.³ While minimally invasive techniques do not alter these core principles, they provide a less morbid approach. The growing adoption of minimally invasive surgery for spinal trauma has been largely driven by advancements in medical imaging, instrumentation, navigation and visualization technologies.⁴ As technology evolves, these tools are expected to refine MIS techniques further and expand their applications in spinal trauma management. MIS techniques have gained traction due to advantages with regards to minimizing paraspinal tissue damage by avoiding extensive exposure and retraction, devascularization and denervation. The diminished footprint of MIS approaches allows for shorter operation duration, less blood loss, shorter hospital stays and early mobilization, which often leads to less medical complications.⁵

In this narrative review, we discuss the available literature and identify knowledge gaps focusing on minimally invasive surgical techniques for TL burst fractures. The aim of this article is to help guide spinal surgeons who wish to include MIS as part of their surgical portfolio. We aimed to present a review on the choice of long vs short construct with index fracture level instrumentation, the use of cement augmentation techniques, the use of reduction and realignment techniques, surgical nuances in incomplete (A3) versus complete (A4) burst fractures, endoscopic and robotic techniques as well as to discuss the role of implant removal in minimally invasive surgical techniques of TL burst fractures.

A narrative review of the literature was performed using PubMed, Google Scholar and Medline databases to identify relevant articles limited to the English language. IRB approval was not required. We searched with key terms relating to MIS surgical techniques in the treatment of TL burst fractures for relevant articles. The search for this narrative review was iterative and involved multiple cycles of searching, analysis and interpretation. Time frame was not strict as MIS literature is inherently recent. Authors aimed to include pivotal and seminal papers as well as papers where novel MIS techniques are described. A descriptive synthesis of the main findings was performed. We present a detailed review for the following techniques: 1) choice between long and short construct as well as the advantage of instrumenting the index fracture level; 2) reduction and realignment techniques with polyaxial vs monoaxial screws as well as ligamentotaxis; 3) cement augmentation techniques; 4) surgical nuances between incomplete (A3) and complete (A4) burst fracture and 5) the role and advantages of implant removal. Anterior column reconstruction and minimally invasive anterolateral approaches will be discussed in detail a different review within this focus issue.

1. Long versus short construct

The surgical management of TL burst fractures has undergone a significant paradigm shift toward minimally invasive surgery. While the fundamental goals remain achieving spinal stability and preserving motion, modern approaches prioritize limiting soft tissue injury.⁶ Two critical advancements facilitating this shift are short-segment fixation with index-level instrumentation and percutaneous pedicle screw placement.^7,8 When combined, these techniques offer a biological advantage over traditional open surgery by minimizing approach-related trauma^9,79.

Historically, open long-segment fixation (instrumenting two levels above and below the fracture) was the gold standard.¹⁰ While effective for stability, particularly in fractures with anterior column compromise, this approach necessitates extensive dissection and the sacrifice of multiple motion segments^{11, 12, 13}. In contrast, early attempts at short-segment fixation using 4-screw constructs spared motion segments but frequently failed, particularly in cases with significant anterior column compromise ^{14, 15, 16, 17}. The evolution to a 6-screw construct, which includes instrumentation at the index level, has mitigated these failures by improving load distribution and stiffness, thereby reducing the risk of kyphosis progression.^11,12,18,19 Consequently, the percutaneous 6-screw construct has emerged as a robust MIS alternative to long-segment fusion ^76.77,78,79.

The widespread adoption of MIS index-level instrumentation has introduced new challenges that the current literature has yet to fully resolve. A primary concern is the risk of iatrogenic neurological deficit caused by placing screws into a fractured vertebral body. While there is a theoretical fear that this technique could worsen spinal canal compromise, recent evidence suggests the opposite—that index level screws may assist in fracture reduction and improve canal clearance⁸⁰. Despite these promising findings, complications such as screw malposition in percutaneous fixation remain a documented risk⁸¹, and the specific safety limits of the technique are unknown. High-level evidence is also lacking to define the "instrumentable" pedicle or the threshold of anterior column compromise necessitating long-segment fixation or anterior reconstruction. Crucially, the majority of existing research comparing short versus long constructs is derived from open or mixed surgical approaches, creating a significant gap in MIS-specific literature. It remains unclear whether historical data based on open procedures can be directly extrapolated to percutaneous techniques.

2. MIS reduction techniques: polyaxial vs monoaxial screws and ligamentotaxis

Unstable burst fractures requiring operative intervention can be characterized by vertebral body height loss, significant canal compromise due to fracture fragment retropulsion, and focal kyphosis, particularly under physiologic loads. One of the operative goals is restoration of native sagittal alignment, namely by restoring vertebral body height and reducing any focal kyphosis. Several MIS techniques exist, which can indirectly achieve the goal of sagittal alignment restoration and fracture reduction.

First, restoration of sagittal alignment can be achieved with closed reduction techniques notably surgical positioning. A patient is typically placed on a lordosis inducing frame with pads under the chest proximally and supporting the pelvis distally. With the abdomen free to hang, the area of the spine between the pads is subject to a lordosing moment. Fluoroscopy can be obtained to plan incisions placement as well as verify alignment obtained during positioning to assess if further restorative alignment techniques will be necessary intraoperatively.

Selection of instrumentation type is important when attempting MIS reduction techniques. While polyaxial screws are often favored by spine surgeons due to the ease of affixing rods following screw insertion, monoaxial screw offer a distinct advantage in reduction of TL burst fractures particularly in restoring both vertebral body height and sagittal alignment. Posterior screw-based reduction techniques are often marred by the coupling of distraction maneuver and lordosing maneuvers with cantilever compression. This can be performed with partial screw tulips fixation to the rod or with posterior reduction tools. The use of monoaxial screw potentiate the result of these techniques by their constrained position perpendicular to the rod. With the rod provisionally secured to the cranial and/or caudal set of screw tulips, distraction and lordosis maneuvers can be performed with cantilever actions. Additionally, if the screws are all placed parallel to the vertebral body endplates, then the spine should take the shape of the rod once secured. Several studies have demonstrated initial restoration of vertebral body height or sagittal Cobb angle with the use of monoaxial screws with both open and MIS techniques.^20,21 Further, several studies have demonstrated less loss of reduction over time with the monoaxial screws as compared to polyaxial screws^{22, 23, 24}.

As compared to AOSpine type B and C TL injuries, the longitudinal ligaments and posterior ligamentous complex are largely intact in A3 and A4 type injuries. However, as the result of injury and vertebral body height loss, the posterior longitudinal ligament (PLL) is often buckled as it encapsulates any retropulsed fracture fragments (Fig. 1A). One method to reduce the fracture and the retropulsed fragment is to tension the PLL, which is referred to as ligamentotaxis. As the intact PLL is tensioned, it can guide the retropulsed fragments anteriorly and decrease canal encroachment so long as a fragment is not flipped such that the cancellous surface lies dorsally (Fig. 1B). For MIS TL burst treatment, two effective means of indirect ligamentotaxis include patient positioning and direct vertebral body manipulation with distraction of the pedicle screws. This is performed ideally with monoaxial screws and with the cranial or caudal screws fixed to the rod. Once the desired amount of distraction is achieved evaluated by fluoroscopy, all screw tulips are fixed to the rods. Though small studies have suggested that improved reduction can be achieved with earlier surgery,^25,26 this has not been demonstrated in larger studies on the matter.

Fig. 1.

(A) Midline sagittal CT in a 26-year-old female presenting with an L3 A4 injury. (B) Midline sagittal T2 demonstrates the buckled posterior longitudinal ligament (yellow arrowheads).

Posterior reduction tools exist which can aid the spine surgeon in achieving the reduction and realignment goals. A reduction device can be fixed to the percutaneous pedicle screw heads (Fig. 2). The system offers the ability to perform multiplanar reduction maneuvers. When the desired reduction and realignment is achieved, rods are fixed and tightened to the system. Hoffman et al. showed that a significant correction of the initial kyphotic malposition is possible with patient positioning and by using a reduction tool (Sagittal index improvement of 0.20 in the reduction tool group versus 0.12 in the control group).²⁷ This study showed a loss of the achieved correction at the follow-up examination, which is consistent with the available literature. However, the vast majority of studies do not show an association between posttraumatic kyphosis and impaired clinical outcomes^{27, 28, 29, 30, 31}.

Fig. 2.

Posterior reduction tool fixed to the percutaneous pedicle screw heads.

As imaging, navigation and technology continue to evolve, the armentarium for MIS techniques for realignment and reduction will continue to expand. The above maneuvers described can be performed with fluoroscopy for intraoperative guidance. Furthermore, TL burst fractures can also lead to coronal malalignment. A clear understanding is lacking regarding the impact of coronal malignment and the best surgical techniques to address it. Additionally, further research is necessary to determine in which cases with greater anterior column failure will the above-described techniques be sufficient and for which cases anterior reconstruction will be necessary for reduction and realignment.

3. Cement augmentation techniques

Minimally invasive vertebral cement augmentation-based techniques (e.g. vertebroplasty and kyphoplasty) have been used for the treatment of spinal osteoporotic and malignant fractures for the last 35 years. Previously used in open tumor surgery to refill the bony defect in the vertebral body,³² the percutaneous application of Polymethylmethacrylate bone cement (PMMA) was first described by Galibert and Deramond for the treatment of vertebral angiomas.³³ It was later used predominantly for the treatment of painful osteoporotic vertebral compression fractures.³⁴ More recently, it is also used for less severe traumatic fractures as AO type A1 and A3 as stand-alone technique³⁵ or in combination with pedicle screw fixation in more unstable situations as in A4 fractures ^{36, 37, 38}. All techniques apply the same principle of increasing the anterior support of the spine column by filling the fracture induced intravertebral void by transcutaneous injection of highly viscous cement (PMMA or CaPh-bone substitutes). Cement augmentation techniques are great adjuncts for MIS instrumentation techniques.

Percutaneous vertebroplasty is a straightforward augmentation technique where the bone cement is directly injected via cannulas of 8-11G diameter. The intervention is performed under local or general anesthesia in prone patient position. The cannulas are placed via a transpedicular (lumbar) or extrapedicular (thoracal) approach into the anterior third of the vertebral body. The cannulas can be placed with fluoroscopic control or CT-based navigation. Re-establishment of lost VB height is not possible with the procedure per se, but can possibly be achieved with additional positioning maneuvers using the principle of ligamentotaxis which is explained more in detail in the above section of this article.³⁹

Kyphoplasty was introduced in 1998 to restore vertebral body height and help realign the spine, using an inflatable balloon to reduce the fracture and restore lordosis and vertebral height. After fracture reduction, the balloons are deflated and removed and the remaining cavity is filled with bone cement ^{40, 41, 42}. It has been reported that a restoration of approximately 70° of the initial VB height is possible, reducing the local kyphosis significantly up to 9,5° in terms of the vertebral kyphosis angle ^{43, 44, 45}. Today, a large variety of balloon kyphoplasty systems are available from many different producers.

In 2006, Orler et al. introduced the concept of lordoplasty, a cost-effective, minimal-invasive cement augmentation technique that allows kyphosis correction of wedge shaped vertebral compression fractures by the principles of ligamentotaxis as it is used by an internal fixateur.⁴⁶ This technique can also be applied to burst fractures. The fractured and the adjacent vertebrae are bipedicular instrumented with vertebroplasty cannulas and the fracture is reduced indirectly by applying a lordotic moment via the cannulas and the facets as hypomochlion (Fig. 3). It is possible to combine this technique with a balloon kyphoplasty or stentoplasty procedure to facilitate fracture reduction of impressed or comminuted endplates. The achieved correction of the kyphosis is larger as compared to percutaneous vertebroplasty, kyphoplasty and stentoplasty.^45,47,48

Fig. 3.

Lordoplasty:

67 years old female patient with a painful 8 week old VCFx. In prone position a fracture kyphosis of 29° persists, after applying a lordotic moment via Jamshidi cannulas at the adjacent vertebrae the fracture could be reduced to 5° and the defect was filled with highly visceous PMMA.

After deflation of the kyphoplasty balloons, a loss of achieved reduction is regularly observed.⁴⁹ In 2010 the Vertebral Body Stenting System (VBS, DePuySynthes) was introduced to maintain the correction. It consists of a balloon-expandable metal stent mounted on a balloon-catheter. After balloon deflation the intrinsic mechanical stability of the expanded rigid stent construct keeps the created cavity open until PMMA-based cement is injected and has cured.⁴⁹ Similar systems are the Kiva VCF Treatments System (Benvenue Medical), which uses a Peek coil instead of an expandable cage. The StaxX Expandable Device (Spine Wave), Spider Somatoplasty system (Sintea Biotech), Osseofix (Alphatec Spine) and SpineJack (Stryker) are examples of stent-like expansion systems for the treatment of VCF which can be used with or without cement augmentation (Fig. 4).

Fig. 4.

41 years old male patient with a mild, traumatic A4 N0 M0 fracture of L1 treated with a percutaneous reposition with vertebral body stent VBS and PMMA. CT scans before and 2 days after treatment, radiographs before and 2 months postoperative.

4. Incomplete (A3) vs complete (A4) burst fracture: Technical nuances

The two types of burst fractures, incomplete (A3) and complete (A4), represent different biomechanical challenges regarding optimal surgical management. With dual end plate fractures and more comminution, A4 burst fractures are thought to have greater biomechanical instability with greater deficits of the anterior column compared to A3. MIS techniques can address the biomechanical nuances of A3 vs A4 fractures.

The preferred MIS surgical approach for the less comminuted single end plate A3 burst fracture is often posterior percutaneous short-segment fixation with instrumentation of the index level whenever possible. This technique provides adequate stabilization while minimizing soft tissue disruption. In patients presenting with neurological deficits, a mini-open posterior decompression can be performed in conjunction to relieve spinal cord or nerve root compression.

A4 fractures with greater comminution and dual end plates fractures have a greater tendency towards instability and severe kyphotic deformity, which may necessitate more extensive fixation and reconstruction strategies. For these fractures, percutaneous pedicle screw fixation can be used as a standalone procedure in less destructive morphologies, as an adjunct to anterior approaches or in combination to cement augmentation techniques. In certain cases where prevention or correction of kyphotic deformity is a goal, MIS approaches for anterior column reconstruction with the utilization of expandable cage systems in combination with posterior percutaneous fixation may be preferred. This approach is particularly useful when severe vertebral body comminution, retropulsion of bony fragments causing significant spinal canal compromise with neurological deficit, or when a significant degree of kyphosis correction is required. Anterior column reconstruction enables shorter-segment fusion, preserving mobility at adjacent levels. Additionally, corpectomy allows for direct anterior canal decompression, facilitating the removal of fracture fragments that encroach upon the spinal canal. This approach also promotes superior sagittal realignment, ensuring optimal biomechanical restoration. Given these benefits, the anterior approach is a valuable option, particularly when posterior-only fixation may not provide sufficient stability or decompression in the context of A4 burst fracture. Li et al. compared traditional open combined anterior-posterior surgery to MIS corpectomy with short-segment posterior instrumentation in patients with TL burst fractures.⁵⁰ They noted equivalent sagittal correction. MIS corpectomy with short-segment percutaneous posterior instrumentation had fewer perioperative complications, shorter operative time, and less blood loss. The approaches, techniques and indications of anterior reconstruction approaches will be further described in another review of this focus issue. Additional high quality investigative efforts are necessary to determine which facture morphology necessitate anterior column reconstruction versus posterior approach only. The literature consolidates most included injuries into a single mixed category including A3 and A4 fractures and even often incorporates B type and C type fractures. This creates a critical knowledge gap in terms of best surgical techniques to address each fracture subtypes. Future studies should distinguish and stratify groups and analysis to facilitate detailed analysis of the outcomes. New reports consisting of mostly case reports and small case series describe the utilization of uniportal and biportal endoscopy for bilateral decompression as an adjunct in the minimally invasive approach to TL burst fractures.^51,52 In patients with secondary spinal stenosis who receive percutaneous pedicle screw fixation, endoscopy is a safe and reliable tool. An important technical note is that the pedicle screws ipsilateral to the endoscopic channel should be placed after the decompression is completed to not interfere.

5. Implant removal

MIS fixation can serve as internal bracing while the fracture heals. Subsequent hardware removal after fracture healing has become a topic of ongoing discussion in spinal surgery. Some authors opt for leaving the instrumentation in situ because of the observed kyphotic correction loss that occurs after implant removal.^53,54 However, many advocate for implant removal while considering the possible benefits of minimizing the adjacent level disease as well as restoring segmental range of motion. A postoperative CT scan can be obtained about 12 months postoperatively to assess fracture healing. Following successful healing of fracture confirmed by CT, implant removal can alleviate discomfort, restore mobility and prevent future fusion related complications^{55, 56, 57, 58, 59}. Hardware should not be removed without evidence of fracture healing on CT and/or if significant malalignment persists. Oh et al. Often, MIS fixation is done without arthrodesis (such as drilling of the facets and addition of either autograft or allograft), rendering simple hardware removal possible.

In the traditional open techniques, removal of implants generally requires a surgical dissection that is somewhat comparable to the extensive dissection during the index surgery, involving reopening large incisions and repeated dissection of the paraspinal musculature. This approach is associated with extended recovery times and higher complication rates, including infection, muscle damage, and postoperative pain. The invasive character of the open procedure might also make it less suitable for certain patients, especially those with comorbidities.^60,61

Overall, the literature regarding hardware removal for TL burst fracture is heterogenous. However, few studies have assessed hardware removal specifically in percutaneous fixation for TL burst fractures. A systematic review and meta-analysis by Kweh et al. investigated the biomechanical and functional outcomes of planned implant removal versus implant retention after posterior surgical fixation of TL burst fractures.⁶⁰ They found that hardware removal in these patients significantly improved clinical outcomes such as pain relief and function as measured by VAS pain score and Oswestry Disability Index scores compared to implant retention.⁶⁰ Additionally, Lee et al. conducted a cost-utility analysis where hardware removal was compared to implant retention. Pedicle screw removal was cost-effective procedure until at 2 years with ICER of 12,896 per quality-adjusted life-years.⁶² While the literature suggests that planned implant removal seem to be beneficial for patients, the long-term fusion-related complications in spinal trauma patients have not been well characterized.

The surgical treatment for TL A3 and A4 burst fractures has evolved over the last decade from conventional open posterior surgeries to more commonly including MIS techniques. Open procedures have been associated with significant blood loss, increased infection rates, and notable approach-related morbidity. MIS techniques have been developed to mitigate these complications. MIS fixation allows for internal bracing to limit segmental motion while the fracture heals with the possibility of subsequent implant removal. This approach offers numerous advantages including reduced tissue trauma, quicker recovery, mobility restoration as well as avoiding long-term fusion related complications such as adjacent segment disease. With the ongoing technological advancement, the armentarium of MIS surgical techniques applicable to TL burst fractures will certainly continue to expand. This narrative review offers a technical overview to guide the spine surgeon wanting to incorporate MIS into practice. This review also offers a portrait of the current knowledge gaps to guide future investigative efforts (Table 1).

Table 1.

Key knowledge gaps identified in the literature for MIS surgical techniques in thoracolumbar burst fractures.

Domain	Key Knowledge gaps
Long vs short construct and index fracture level instrumentation	•Defining the radiographic features that affect pedicle integrity at the fracture level preventing index fracture level instrumentation •Identify threshold of anterior column compromise where short construct will be insufficient, and longer construct will be necessary
MIS reduction techniques with polyaxial vs monoaxial screws and ligamentotaxis	•Determine the impact of coronal malalignment and best surgical techniques •Identify features of anterior column failure where MIS techniques will be insufficient and anterior column reconstruction will be necessary for reduction and realignment
Cement augmentation techniques	•Characterize fracture type and patient factors which are best suited for anterior column reconstruction versus cement augmentation
Surgical nuances in incomplete (A3) vs complete (A4) burst fractures	•Recognize the need to stratify future research by fracture type to identify best surgical approach for each fracture type
Implant removal	•While planned implant removal shows advantages for patient, long-term fusion related complications are not well defined in the spinal trauma population

Percutaneous stabilization has shown a significantly lower infection rate (1.9% vs. 6.4%), reduced surgical time (114 min vs. 151 min), and decreased blood loss (73 mL vs. 334 mL) compared to open stabilization.⁶³ A systematic review indicated that internal fixation using posterior percutaneous pedicle screws had a shorter operation time, lower pain, a better cobb angle recovery, and a lower postoperative screw dislocation rate and postoperative infection rate compared to open surgery.⁶⁴ Visualization for percutaneous pedicle screws can be achieved through conventional fluoroscopy, 3D fluoroscopy navigation, CT navigation, and robotic guidance. Historical concerns existed in terms of screw misplacement, pedicle breach, facet joint violation, and radiation exposure with percutaneous instrumentation. However, the significant recent technological progress of navigation and robotic guidance improves screw accuracy, decreases facet violation, and reduces radiation exposure to the patient and surgical team^{65, 66, 67}. Future reviews should focus on navigation and robotics for additional guidance for surgeons incorporating MIS into their practice. When decompression is necessary, microscopic tubular and endoscopic techniques have recently been described in small case series. As shown in the scientific literature and this review, MIS is a promising option for spine surgeons looking to improve patient outcomes while minimizing recovery time and risks associated with traditional open procedures.

Percutaneously placed short-segment fixation with index-level instrumentation is a minimally invasive technique that enhances construct stability and improves fracture site fixation. This makes it a favorable alternative to open, long-segment fixation from both a biomechanical and cost perspective. The choice between short and long constructs is still somewhat controversial, and the decision should be individualized based on fracture morphology and alignment, as well as patient-specific factors such as bone quality.¹⁸ As clinical evidence continues to support the use of short constructs with index-level instrumentation, it is likely to become an increasingly popular option for treating TL burst fractures. Mild kyphotic deformity and restoration alignment can be addressed via the MIS approach with positioning, screw manipulation maneuvers and ligamentotaxis as described in this article. Cement augmentation can be considered for anterior column support in the osteoporotic population as well as the elderly population with low energy trauma. Further prospective comparative research is necessary to determine in which cases with greater anterior column failure will the above-described techniques be sufficient and for which cases a long posterior construct and/or anterior reconstruction will be necessary for reduction and realignment. A recent meta-analysis has attempted to evaluate and compare short-term and long-term outcomes in patient with neurologically intact TL burst fractures who underwent anterior fusion, combined anterior-posterior procedure, or short-segment pedicle screw fixation.⁶⁸ This meta-analysis identified a significant lack of comparative studies and high-level evidence affecting the methodology and quality of the analysis. Comparison of long-term functional and radiological outcomes across MIS techniques is missing from the literature.

Furthermore, with the shift from open surgery to MIS surgery, some clinicians argue that MIS techniques do not allow for proper surgical fusion. However, several studies have compared fixation only versus fusion in TL burst fractures^{69, 70, 71, 72, 73}. Numerous studies have shown that the use of arthrodesis did not influence clinical and functional outcomes^{69, 70, 71, 72, 73}. Furthermore, the use of arthrodesis did not promote significant improvement in radiological parameters. However, fixation only (non-fusion) may have slightly decreased vertebral body height in radiographic follow-up. Conversely, open surgical fusion increased OR time and blood loss. Therefore, the role of surgical fusion or arthrodesis may not be a concern when treating a patient with MIS techniques when appropriate.

Cement augmentation can be used as an adjuvant tool for minimally invasive instrumentation. Both vertebroplasty and kyphoplasty can be used in the treatment of fractures with deficit of the anterior column type A (especially in type A4). This technique allows for a less invasive support of the anterior column as compared to combined anterior column reconstruction with posterior long-segment constructs, with less morbidity and shorter hospitalization times ^{36, 37, 38}. The use of balloons or stents allow for reposition of endplate fragments which may be beneficial to minimize posttraumatic discopathy.⁷⁴ This is important if implant removal to avoid permanent fusion related complications is planned. Hoppe et al. have shown excellent clinical and radiological results in a cohort of 59 patients undergoing VP/KP combined with short segment fixation and implant removal after approximately 6 months but also observed a loss of correction of approximately 7° originating from the disc space adjacent to the fracture.⁷⁵ These techniques may be especially useful in patients with burst fractures associated with poor bone stocks and low energy traumas, although not restrict to this population.

Percutaneous pedicle screw fixation can be used as both a standalone procedure and an adjunct to anterior approaches in A3 and A4 TL burst fracture. While the current literature offers valid comparisons between anterior, posterior, and combined approaches for TL burst fractures, most of the available studies are based on open procedures, and often lump A3 and A4 fractures together under a single category. This makes it difficult to draw clear conclusions, especially considering that A3 and A4 fractures differ in their biomechanical demands and clinical presentation. As minimally invasive surgical (MIS) techniques continue to evolve and become more widely used, there is a real need for focused, prospective studies that directly compare MIS-based approaches between A3 versus A4 fractures. Such studies would provide more nuanced, evidence-based guidance and support individualized surgical decision-making based on fracture morphology and patient-specific considerations.

6. Conclusion

MIS management of TL burst (both A3 and A4) fractures is another valuable tool in the armamentarium of the spine surgeon. Percutaneous pedicle screw fixation including the index fracture level and subsequent implant removal has shown promise for the surgical treatment of TL AO Type A3 fractures, and A4 fractures. This technique may be best considered as internal bracing while fracture heals with the prototypical patient being a young active individual without severe kyphotic deformity. These techniques can be enhanced with cement augmentation as well as reduction and realignment techniques. With ongoing technological advancement, the armentarium of MIS surgical techniques applicable to TL burst fractures will certainly continue to expand. Future investigative efforts should aim at addressing the knowledge gaps identify via this narrative review.

Ethical approval

Ethical approval was not required for this narrative review of the literature.

Statement of authorship

CD: conceptualization, data curation, writing, results interpretation.

LB: data curation, writing.

SS: data curation, writing.

AEN: data curation, writing.

SR: data curation, writing.

JM: data curation, writing.

AFJ: manuscript review and editing.

GS: manuscript review and editing.

SB: manuscript review and editing.

HSC: manuscript review and editing.

RB: Conceptualization, manuscript review and editing.

KJS: Conceptualization, manuscript review and editing.

All authors reviewed the results and approved the final version of the manuscript.

Funding Acknowledgements

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was organized and funded by AO Spine through the AO Spine Knowledge Forum Trauma & Infection. Study support was provided directly through AO Network Clinical Research.

Patient and/or guardian consent

Not applicable.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.