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Abstract
Background Complex thoracolumbar fractures require reduction and stabilization. Posterior instrumentation alone and standard cement augmentation may represent undertreatment, while corpectomy has significant morbidity. In a series of unstable thoracolumbar fractures, we assessed the feasibility, safety, and results of ‘armed kyphoplasty’ (AKP) and surgical posterior stabilization (PS).
Methods A total of 24 consecutive patients were treated with combined AKP and PS. Minimally invasive and open surgery techniques were used for PS. AKP was performed with C-arm or biplane fluoroscopic guidance, and screws were placed under navigation or fluoroscopic guidance. A postoperative CT scan and standing plain films were obtained. Patients were followed up according to clinical standards. Kyphosis correction (measured with regional Cobb angle), pain (measured with the Numeric Rating Scale), neurological status (measured with Frankel grade) were assessed.
Results A total of 25 fractures of neoplastic (40%), traumatic (32%), and osteoporotic (28%) nature were treated. Open surgery and minimally invasive techniques were applied in 16/24 and 8/24 patients, respectively. Decompressive laminectomy was performed in 13 cases. No intraprocedural complications occurred. Two patients (8%) died due to underlying disease complications and three complications (12%) required re-intervention (one surgical site infection, one adjacent fracture, and one screw pull-out) in the first month. The mean Cobb angle was 20.14±6.19° before treatment and 11.66±5.24° after treatment (P<0.0001). No re-fractures occurred at the treated levels.
Conclusions Combined AKP and PS is feasible and effective in the treatment of complex thoracolumbar fractures of all etiologies. AKP avoided highly invasive corpectomy. Anterior and posterior support ensured stability, preventing implant failure and re-fracture. The complication rate was low compared with more invasive traditional 360° open surgical approaches.
- Spine
- Trauma
- Tumor
- Technique
- Device
Data availability statement
Data are available upon reasonable request.
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WHAT IS ALREADY KNOWN ON THIS TOPIC
Complex thoracolumbar fractures of osteoporotic, traumatic, or neoplastic nature must be treated with anterior and posterior support for optimal stabilization. This means posterior fixation associated with corpectomy via a dorsal or ventrolateral approach, which is often associated with high complication and mortality rates and is not feasible for certain types of patients.
WHAT THIS STUDY ADDS
This study investigates the feasibility of a newer approach to effectively treat these fractures with a less invasive technique which ensures anterior and posterior column stability.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
The technique investigated in the present study could be applied in larger series to be implemented in daily practice.
Introduction
Complex unstable traumatic, osteoporotic, or neoplastic thoracolumbar fractures featuring burst morphology, pseudoarthrosis, extreme collapse and kyphosis, or extensive osteolysis generally require surgical stabilization. The goal of treatment, regardless of the cause of fracture, is obtaining stabilization and axial load capability, restoring vertebral body height (VBH) and sagittal alignment, thereby avoiding the onset or the progression of neurological deficit.1 2
Posterior stabilization (PS) through pedicle screws is usually recommended. However, the lack of support in the anterior column may overload the posterior instrumentation and lead to delayed failure with secondary loss of VBH and progressive deformity.3
For this reason, anterior column reconstruction is usually recommended when the fracture is associated with certain radiological features such as loss of >50% anterior VBH, local kyphosis >20°, or canal encroachment >50%.3 Strategies to obtain anterior reconstruction encompass different surgical approaches; between them, the anterior approach with canal decompression, kyphosis correction and reconstruction with titanium cages gives the best immediate and long-term kyphosis correction. Alternatively, a posterior-only approach with anterior reconstruction via an extracavitary approach is a valid alternative, depending on the surgeon’s choice.3 However, there is an increased risk of perioperative complications when these approaches are chosen, especially in elderly patients. Anterior column augmentation through a transpedicular route may be a valid alternative. Previous experiences have shown the feasibility of intracorporeal bone grafting by morselized autograft; however, this technique has not proven to be successful, despite initial promising results, mainly because of resorption of the graft.
Recently introduced vertebral augmentation techniques using expandable intravertebral implants such as vertebral body stenting (VBS) (DePuy-Synthes, Johnson&Johnson), stent-screw assisted internal fixation (SAIF), and SpineJack (SJ) (Stryker, Kalamazoo, Michigan, USA) could allow for an effective yet minimally invasive anterior column reconstruction, and could be defined as ‘armed kyphoplasty’ (AKP) as the construct is reinforced with metallic implants which provide more stability.2 4–6
The aim of the present study is to evaluate the feasibility, safety, and results of a dorsal instrumentation (with or without decompressive laminectomy) combined with different minimally invasive AKP techniques to reconstruct the anterior column in a series of unstable thoracolumbar spine fractures in patients not considered eligible for an anterior surgical approach.
The primary outcome was the complication rate at 30 days. Secondary outcomes were pain, neurological status, and kyphosis correction.
Methods
The study is a single-center retrospective evaluation of a prospectively maintained database of consecutive cases treated with combined PS and AKP over a period of 7 years. We aimed to identify patients admitted for unstable traumatic, osteoporotic, and neoplastic thoracolumbar fractures who were not considered suitable for anterior stabilization and reconstruction due to age and/or associated comorbidities, and therefore were treated with PS in combination with AKP techniques.
Preoperatively, the following variables were assessed:
Demographic data.
Numeric Rating Scale (NRS) for back pain. Pain intensity is assessed on an 11-point scale ranging from 0 (no pain at all) to 10 (the worst imaginable pain).
Etiology of the fracture (traumatic, neoplastic, or osteoporotic). Osteoporotic fractures were defined as fractures occurring spontaneously or after minor trauma in patients without a documented vertebral lesion (ie, neoplasm, hemangioma).7
Fracture level: thoracic (T1–T11), thoracolumbar junction (T12–L1), lumbar (L2–L5).
Spinal cord function, assessed with Frankel grade classification.
The indications for treatment were posed by a spine care multidisciplinary board composed of spinal neurosurgeons, neuroradiologists and, when necessary, oncologists and radiation oncologists. Inclusion criteria following the multidisciplinary board assessment were an unstable thoracolumbar vertebral fracture requiring surgical stabilization with advanced loss of structural integrity of the vertebral body, so that anterior column reconstruction was indicated and standard vertebral augmentation alone was considered not feasible or an undertreatment.
Patients were investigated preoperatively with plain films, CT and MRI. Traumatic fractures were classified according to the AO Spine Classification System,8 osteoporotic fracture with the OF Classification System,9 and oncological fractures based on the Spine Instability Neoplastic Score (SINS)10 to assess stability.
Patients were treated combining AKP and either short or long PS. Short construct refers to instrumentation of one level above and one below the index level, and long construct was considered two levels above and two below the index vertebra or more, according to the pathology and the instability of the fracture. The two portions of the procedure were performed concurrently or separately, but within the same hospitalization.
In the case of spinal cord or cauda equina compression, laminectomy was performed as the initial step of the procedure. Both minimally invasive and open surgery techniques were used for the PS. The length of the construct was chosen according to the mechanism of injury, radiological features, fracture type and bone quality, as well as the preoperative degree of kyphosis; when possible, shorter constructs were preferred. Screws were placed with the aid of 3D navigation using O-arm or intraoperative CT (AIRO) imaging technologies or under fluoroscopic guidance, depending on the surgeon’s preference.
When procedures were performed concurrently, AKP was performed using a single plane fluoroscopy unit in the operating room. When they were staged at different times, AKP was performed with a biplane angiosuite fluoroscopy unit. AKP was performed using the VBS, SJ, or SAIF technique, consisting of additional insertion of fenestrated pedicular screws in the stents. In neoplastic fractures, if severe osteolysis involved one pedicle, only one screw was inserted in the contralateral healthy pedicle. In the case of bilateral severe pedicular osteolysis, VBS was preferably performed not involving the use of pedicular screws. AKP was performed according to the reported techniques for either device.4 5 11
Postoperative follow-up
Surgical complications at 30 days were recorded. All patients underwent CT and standing anteroposterior and lateral X-rays within the first postoperative days to check screws and device placement and to assess VBH restoration and effectiveness of the construct to correct kyphosis. A new standing X-ray was then performed at 4 weeks for all patients. Further radiological examinations including MRI were performed according to the clinical status and the underlying pathology. Regional Cobb angle (measured as the angle between the superior endplate of the vertebra above and the inferior endplate of the vertebra below the index level in the sagittal plane, see figure 1A, B) was measured on lateral plain films preoperatively and postoperatively at the first early postoperative X-ray, as well as at 4 weeks and at the last available examination, to assess the stability of the kyphosis correction.
(A) Standing lateral radiograph of a patient with L1 fracture with vertebra plana morphology and hyperkyphosis. The regional Cobb angle is shown (continous white lines) along the endplates of T12 and L2. The patient was treated with a stent-screw assisted internal fixation (SAIF) kyphoplasty at L1 and short (one level above and below) percutaneous posterior stabilization in a single session. (B) Post-procedural standing radiograph shows reduction of the regional Cobb angle from 29° to 8°. (C–H) Case example. Axial (C), sagittal (D) and coronal (E) CT scan reconstructions in a patient with a neoplastic osteolytic lesion of T6 with intense mechanical pain (plasmocytoma; Spine Instability Neoplastic Score (SINS) score 11 points). Extensive osteolysis of the vertebral body with fracture of both endplates and partial collapse is observed. Extension of the osteolysis to the left pedicle and sagittal imbalance with focal scoliois is also visible. Coronal thin section (F), axial MIP (G) and sagittal MIP (H) reconstructions of CT scan after treatment with SAIF kyphoplasty (with a single screw in the right pedicle due to the osteolysis of the contralateral pedicle) and short (T5–T7) posterior stabilization. The patient experienced early recovery with pain reduction and the result was stable at follow-up after 24 months (H).
Statistical analysis
The data groups were tested for normality with Shapiro–Wilk and Kolmogorov–Smirnov tests and a paired one-tailed t-test was performed with α=0.05. Effect size was also estimated. We also performed Brown–Forsythe and Welch’s ANOVA tests to assess whether there was a difference in Cobb angle reduction between AKP performed in the angiosuite with the bi-plane C-arm and procedures performed in the operating room with the single C-arm.
For pain assessment, data groups were tested for normality with Shapiro–Wilk and Kolmogorov–Smirnov tests and a paired one-tailed t-test was performed with α=0.05. For neurological status assessment we performed a Wilcoxon signed-rank test with α=0.05.
Results
The patient characteristics are summarized in table 1.
Summary of all relevant patient data. Instrumentation: short (1 level above and 1 below the index level); long (≥2 levels above and ≥2 levels below the index level)
Twenty-four patients (14 men, 10 women) of mean±SD age 68.9±3.41 years (range 53–83) were treated for 25 thoracolumbar fractures of various etiologies between 2013 and 2020. Fracture etiology was neoplastic in 10 (40%), osteoporotic in eight (32%), and traumatic in seven (28%). Among the neoplastic fractures, five patients had a SINS score of 12, two patients had a score of 14, and three patients had a score of 9, 11 and 16, respectively. The osteoporotic fractures were OF3 in one case, OF4 in four cases, and OF5 in two patients. Among the traumatic fractures, one fracture was A2, two fractures were A3, three A4, and one was B2.
Seven fractures involved the thoracic spine, 13 the thoracolumbar junction (7 T12, 6 L1) and four involved the lumbar spine. One patient was treated twice for an adjacent fracture observed during follow-up (see below). The mean±SD NRS score at admission was 6.53±0.71 and the mean±SD NRS score at discharge was 2.63±0.75 (P<0.0001) (figure 2A).
Clinical outcomes. (A) Pain assessment with Numeric Rating Scale at admission and discharge showing a significant improvement in pain pre- and postoperatively. (B) Neurological status assessment with Frankel grade at admission and discharge showing no worsening of neurological status pre- and postoperatively.
No patients presented with Frankel grade A or B preoperatively, one patient presented with Frankel grade C, while the remainder presented with grade D4 or E.12 At discharge we observed no patients with Frankel grades A, B or C, three patients with Frankel grade D and 21 with Frankel grade E (figure 2B). Overall, no patient had neurological worsening at 1 month.
Fourteen AKP procedures were performed in the angiosuite and 11 in the operating room with the mobile C-arm. Eight cases were treated with minimally invasive surgery techniques and use of percutaneous screws, and 17 cases with open surgery. In 13 cases, spinal canal decompression with laminectomy was performed due to spinal cord compression. There were no intraoperative blood losses requiring blood transfusions.
The mean follow-up time was 14.96 months (range 1–57 months). Two patients died in the first month, one on the second postoperative day due to pulmonary embolism and one on postoperative day 28 due to sepsis linked to pulmonary infection; both patients had advanced lung cancer. The remaining 22 patients were followed for at least 1 month, 15 patients were followed for at least 6 months, and 11 patients for at least 12 months.
Complications included early pedicular screw pullout at the postoperative standing X-rays which needed a re-intervention in one case, surgical site infection at 1 month requiring treatment in a female patient affected by breast cancer in one case, and an adjacent fracture with pedicular screw pullout in a severe osteoporotic patient at 1 month requiring re-treatment with the same technique (AKP plus extension of the PS); this second procedure is included in our series.
No symptomatic polymethyl methacrylate leak occurred and we observed no re-fractures of the index treated levels nor mobilization of the AKP intrasomatic devices. No further implant mobilization or failure was observed during the later follow-up.
The mean preoperative Cobb angle was 20.14±6.19° (95% CI), the mean early postoperative Cobb angle was 11.6±5.21° (95% CI), the mean Cobb angle at 4 weeks was 11.66±5.11° (95% CI) and at the end of follow-up was 12.3±5.39° (95% CI). The one-tailed paired t-test showed a highly significant difference between the preoperative and postoperative Cobb angle (P<0.0001), with a relatively good effect size (0.58), as shown in Fig. 3A; the difference was still significant between the preoperative and postoperative Cobb angle at 4 weeks (P=0.03) and at the end of follow-up (P=0.04), while it was stable without a significant difference between the postoperative values (early postoperative, at 4 weeks, and at the last available follow-up) (figure 3).
Radiological outcomes. (A) Regional Cobb angle (°) pre- and postoperatively as measured by standing X-rays (see figure 1) showing a significant kyphosis correction. (B) Regional Cobb angle (°) preoperatively, immediately postoperatively, at 4 weeks, and at the last available follow-up as measured by standing X-rays (see figure 1) showing no loss of kyphosis correction during follow-up.
The mean preoperative Cobb angle in the angiosuite group was 19.54±8.47° and the mean preoperative Cobb angle in the operating room group was 20.89±9.48°. The mean postoperative Cobb angle in the angiosuite group was 12.94±8.23° and the mean postoperative Cobb angle in the operating room group was 10.03±6.01°. The Brown–Forsythe and Welch ANOVA tests showed no significant difference (P=0.2321 and P=0.1927, respectively), as well as the Dunnett’s multiple comparison test (see figure 2, online supplemental material).
Supplemental material
A representative case is shown in figure 1C-H. This is patient number 11, who had a neoplastic osteolytic lesion of T6 with intense mechanical pain treated with the SAIF technique associated with a short posterior fixation. A second illustrative case is shown in figure 1, online supplemental material.
Discussion
In this study, patients with unstable thoracolumbar fractures of traumatic, osteoporotic, or neoplastic origin requiring anterior column reconstruction were treated with a combined approach of AKP and PS, avoiding the need for a more invasive corpectomy. None of the patients required additional surgery at the same level during the follow-up period.
AKP was performed using VBS in 11 cases, SAIF in 12 cases, and SJ in two cases. SJ was chosen for young patients with traumatic fractures requiring strong internal distraction, while VBS was used for patients with compromised bone quality where internal support was needed.13 The SAIF technique, involving transpedicular screws followed by cement injection, was considered in cases with extensive vertebral body fragmentation or cortical bone discontinuity that posed a risk of VBS-cement complex disodgement or to stabilize a middle column fracture.2 14–16
Severe fractures with burst morphology, large pseudoarthrosis clefts, extreme collapse, osteolysis, pedicular or middle column involvement carry a significant risk of severe kyphosis and central canal compromise, necessitating effective and early treatment.1 2 Surgical strategies have varied, with some cases involving only PS, anterior instrumentation, or a combination of both. However, for complex thoracolumbar fractures with unstable features, anterior and posterior support is typically required, each carrying its own set of risks.
In patients surgically treated for spinal metastases, the overall complication rate is high, both perioperatively (24–36%) and in the late postoperative period (11–15%), ranging from infection to implant failure requiring revision, wound problems, deep venous thrombosis, and other medical conditions.17 18 Regarding osteoporotic fractures, the patient population is characterized by being elderly, with comorbidities and poor bone quality, so that complication rate of surgical stabilization reaches 30% overall with peaks of up to 85% in patients with conditions like ankylosing spondylitis.19 In osteoporotic patients proximal or distal junctional problems can occur in 6–40% of cases.12 In traumatic cases the complication rates are lower, probably due to the younger age of the patients, but nonetheless still considerable with rates ranging from 6–8% up to 25%.7 20 The reported complication rates exclusively related to the anterior approaches range between 11% and 32%, including major vascular injury, peritoneal/bowel injury, postoperative ileus, superior hypogastric plexus disruption, retrograde ejaculation in men, urethral injury, and postoperative hernias, with revision rates up to 25%.21
Recent less invasive cement augmentation techniques have emerged, offering potential pain relief, but they may not be suitable for severe fractures with extreme collapse or middle column fracture.22 23 While combined approaches with PS and anterior cement support have been reported in the literature for traumatic, osteoporotic, and neoplastic fractures, they often refer to standard vertebral augmentation methods like vertebroplasty or balloon kyphoplasty.24–27
In a 2005 study, Verlaan et al reported good radiological outcomes for thoracolumbar traumatic burst fractures treated with balloon kyphoplasty and short PS,28 but the clinical outcomes showed a decline in the long-term follow-up.29 Other studies by Lee et al 30 and Zhang et al 31 reported positive outcomes for severe osteoporotic fractures with spinal cord compression through posterior open surgical decompression and instrumentation associated with vertebroplasty. Moussazadeh et al 14 described a cohort of patients with unstable metastatic thoracolumbar fractures treated with percutaneous PS and vertebral augmentation, with cement injected above and below the fracture level.
The feasibility of combining AKP and PS was investigated by Mohammed et al in a recent study involving patients with severely lytic metastatic thoracolumbar fractures,32 as well as by Salle et al for traumatic fractures.33
In the present study, AKP was considered for patients with severe vertebral body injuries where augmentation alone was deemed unsafe or an undertreatment following evaluation by a multidisciplinary team. While corpectomy and grafting were considered, the patients’ comorbidities and frail conditions led to the adoption of a less invasive AKP procedure combined with PS, seen as a reasonable compromise.
Our study background and procedural data align with previous research, demonstrating the effectiveness of this combined approach in reducing fractures and improving alignment, resulting in good kyphosis correction. We also found that AKP could be performed in various settings, including the angiosuite or the operating room, using single or bi-plane C-arms, with similar results. Moreover, we observed sustained long-term kyphosis correction without significant loss of correction compared with vertebroplasty or balloon kyphoplasty. This improvement is hypothesized to be attributed to the solid structure provided by the ‘armor’ of the stents or SpineJack, as demonstrated in a recent study on a cohort of patients with ‘vertebra plana’.34
The main distinctions between our series and previous studies are that we applied this approach to treat all types of vertebral fractures, regardless of their cause, and that we employed a novel AKP approach (VBS, SJ, or SAIF) tailored to the fracture etiology and radiological features, ensuring enhanced stability and biomechanical effectiveness, as demonstrated in a study by La Barbera et al.16 Although there are studies supporting posterior fixation alone or even anterior stabilization alone, most authors agree on the need for a 360° approach in cases of complex, severe, and highly unstable fractures. Our approach ensures a 360° stabilization avoiding the invasiveness of the standard surgical anterior reconstruction.
Overall, the present work shows significant benefits in patient-reported pain relief and in deformity correction, which is also stable over time, ensuring a low rate of complications in a high-risk patient group.
The primary limitations of this study include the small size of the cohort, the single-center recruitment, and the retrospective design, as well as the relatively short-term follow-up. The mixed patient groups could also be seen as a limitation but, on the other hand, it might be proving the versatility of the technique.
Conclusion
This study suggests that PS combined with AKP is a feasible, safe, and effective technique that provides anterior and posterior support to the spine, avoiding more invasive surgical approaches, and prevents implant failure or re-fracture of the treated levels. AKP techniques are more effective than simple vertebroplasty or balloon kyphoplasty in terms of mechanical stability, and this enhances the efficacy of the whole construct. Decompressive laminectomy can be performed when necessary, without fearing secondary instability. In addition, the anterior column support allows for shorter PS when possible. Further investigations with prospective larger series are needed to obtain better evidence and implement this technique in daily clinical practice.
Data availability statement
Data are available upon reasonable request.
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants and was approved by the Ethics Committee of Canton TicinoONCOVERT 1, ID14-136. Participants gave informed consent to participate in the study before taking part.
References
Supplementary materials
Supplementary Data
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Footnotes
Correction notice Since this paper first published, a second affiliation has been added for Professor Cianfoni.
Contributors Conception and design: LB, PS, AC. Acquisition and data: LB, MP, AC. Analysis and interpretation of data: LB, FM, PS, AC. Drafting of the manuscript: LB. Statistical analysis: LB. Critical revision of the manuscript: LB, MP, FM, PS, AC. Supervision: PS, AC. Admínistrative, technical or material support: LB, MP, FM. PS and AC are joint last authors. Guarantor: AC
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.
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