Pedicle screw fixation of thoracolumbar fractures: conventional short segment versus short segment with intermediate screws at the fracture level-a systematic review and meta-analysis.

OBJECTIVE: Posterior short-segment fixation (4-screw construct = 4S) is the conventional surgical technique for thoracolumbar fractures. The effect of adding two intermediate pedicle screws at the fractured level (6-screw construct = 6S) is still a matter of debate. This review aims to compare the results between 4 and 6S pedicle screw fixation for thoracolumbar fractures. METHODS: A systematic review and meta-analysis were performed. The databases PubMed, Embase and Google Scholar were searched until January 2020. Inclusion criteria were studies comparing 4S and 6S techniques in patients with thoracolumbar fractures. Non-comparative studies and studies without full text were excluded. Cochrane risk of bias was assessed, and the GRADE approach was used to present the quality of evidence. RESULTS: Twenty-seven studies, of which 21 randomized controlled trials, with a total of 1890 patients (940 with 4S and 950 with 6S) were included. Meta-analysis showed that the 6S technique resulted in significantly lower pain scores, better short-term and long-term Cobb angles, less loss of correction and less implant failures. However, longer operation time and more blood loss were seen with the 6S technique. Length of hospital stay, Oswestry Disability Index scores and infections did not differ significantly between the 6S and 4S techniques. Quality of the evidence according to GRADE was moderate to low. CONCLUSION: In the treatment of thoracolumbar fractures, adding intermediate screws at the fracture level (6S) results in less post-operative pain, better radiological outcomes and less implant failure at the cost of a longer operation time and higher blood loss.

Minimally invasive fixation techniques for thoracolumbar fractures: comparison between percutaneous pedicle screw with intermediate screw (PPSIS) and percutaneous pedicle screw with kyphoplasty (PPSK).

PURPOSE: To assess and compare the efficacy of two minimally invasive techniques (percutaneous pedicle screw with intermediate screw vs. percutaneous pedicle screw with kyphoplasty) for spinal fracture fixation by comparing the segmental kyphosis and vertebral kyphosis angles after trauma before surgery, after surgery, and at 4-month and 12-month follow-up. METHODS: Data from 49 patients without neurological deficit treated by either percutaneous pedicle screw with intermediate screw or percutaneous pedicle screw with kyphoplasty were retrospectively analysed. The segmental kyphosis and vertebral kyphosis angles over time were calculated and correlated with the type of procedure, AO classification, lumbar or thoracic site and the age and sex of the patients. RESULTS: After surgery, both techniques were found to be efficacious means of bringing about a significant correction of the segmental kyphosis angle (p = 0.002) and a just significant correction of the vertebral kyphosis angle (p = 0.06), although less effectively in thoracic fractures (p = 0.004). At follow-up, the vertebral kyphosis angle was stable in both groups, while there was a significant loss of segmental kyphosis angle stability in the percutaneous pedicle screw with kyphoplasty group at 1 year (p = 0.004); fractured thoracic vertebrae maintained a greater vertebral kyphosis angle (p = 0.06) and segmental kyphosis angle (p < 0.001), than the lumbar. CONCLUSION: At 1 year after surgery, the use of intermediate screws in fractured vertebrae seemed to maintain a more efficacious correction with respect to kyphoplasty, although thoracic fracture sites appear to be associated with greater post-traumatic segmental kyphosis and lesser stability in the long term after both percutaneous surgical techniques.

Short segment posterior fixation of unstable thoracolumbar vertebral fractures with fractured vertebra augmentation with intermediate pedicle screw - a clinicoradiological analysis.

INTRODUCTION: Unstable thoracolumbar burst fractures are routinely encountered in orthopedic practice. Recently, short-segment fixation with pedicle screw augmentation of the fractured vertebra for unstable thoracolumbar burst fractures has gained popularity. Nonetheless, the maintenance of the kyphotic correction during the follow-up period remains controversial. This study aimed to examine the clinical-radiological outcomes, complications, and functional outcomes of fractured vertebrae augmentation with intermediate pedicle screws in short-segment instrumentation in acute thoracolumbar spine fractures. METHODS: This retrospective study was conducted in the Department of Orthopedics, All India Institute of Medical Sciences, Jodhpur, using medical records from January 2021 to October 2022. Parameters such as local kyphosis correction, loss of kyphotic correction at final follow-up, anterior body height correction (%), and loss of correction (%) at final follow-up were measured as primary outcomes. Various other parameters such as operative time, blood loss, length of hospital stay, and visual analog scale were measured as secondary outcomes. RESULTS: The mean correction obtained via surgery in the immediate postoperative period was 13.7±2.3 degrees. The mean loss of correction at the final follow-up was 4.1±2.0 degrees, and the mean final local kyphotic angle was 7.2±2.4 degrees (P<0.05). The mean correction obtained via surgery in the immediate postoperative period was 37.2%±9.0%. The mean loss of correction at the final follow-up was 10.5%±5.3%, and the mean final anterior vertebral body height maintained was 72%±11.0% (P<0.05). CONCLUSION: Short-segment posterior fixation with pedicle screw augmentation achieves good correction of local kyphotic angle and anterior vertebral height in the immediate postoperative period, but some loss of correction at final follow-up is common. In our study, the loss of correction corresponded directly to the load-sharing score.

Percutaneous monoplanar screws versus hybrid fixed axial and polyaxial screws in intermediate screw fixation for traumatic thoracolumbar burst fractures: a case-control study.

BACKGROUND: To compare the clinical and radiological outcomes of monoplanar screws (MSs) versus hybrid fixed axial and polyaxial screws (HSs) in percutaneous short-segment intermediate screw fixation (PSISF) for traumatic thoracolumbar burst fractures (TTBFs) in patients without neurologic impairment. METHODS: A consecutive series of 100 patients with single-segment TTBFs and no neurologic impairment who underwent PSISF with 6 monoplanar screws (MS group) or correct were retrospectively enrolled. The demographic data, radiologic evaluation indicators, perioperative indicators and clinical assessment indicators were analysed between the MS group and HS group. RESULTS: The demographic data and perioperative indicators were not significantly different in the two groups (P > 0.05). The postoperative anterior vertebral height ratio (AVHR), kyphosis Cobb angle (KCA), vertebral wedge angle (VWA) and spinal canal encroachment rate (SCER) were significantly improved in both groups (*P < 0.05). The MS group obtained better correction than the HS group in terms of improvement in the AVHR, KCA and VWA after surgery (*P < 0.05). At the last follow-up, the MS group had less correction loss of AVHR, KCA and VWA (*P < 0.05). The MS group presented greater improvement in the SCER at the last follow-up (*P < 0.05). The visual analogue scale (VAS) score and Oswestry Disability Index (ODI) score of all patients were significantly better postoperatively than those preoperatively (*P < 0.05), and the scores collected at each follow-up visit did not differ significantly between the two groups (P > 0.05). In the MS group, no internal fixation failure was observed during the follow-up period, but, in the HS group, two cases of internal fixation failure were observed at the last follow-up (one case of rod loosening and one case of screw breakage). CONCLUSIONS: Both MSs and HSs fixation are effective treatments for TTBFs and have comparable clinical outcomes. In contrast, MSs fixation can improve the correction effect, better improve the SCER, and further reduce correction loss as well as reduce the incidence of instrumentation failure. Therefore, MSs fixation might be a better option for treating TTBFs in patients without neurological deficits.

Biomechanical Comparison Between Posterior Long-Segment Fixation, Short-Segment Fixation, and Short-Segment Fixation With Intermediate Screws for the Treatment of Thoracolumbar Burst Fracture: A Finite Element Analysis.

BACKGROUND: Posterior long-segment (LS) fixation, short-segment (SS) fixation, and short segment fixation with intermediate screws (SI) have shown good outcomes for the treatment of thoracolumbar burst fractures. However, limited data compared the biomechanical properties between LS fixation and SI. The purpose of this study was to compare the von Mises stresses on the pedicular screw system and bone between posterior LS fixation, SS fixation, and SI for the treatment of thoracolumbar burst fracture. MATERIALS AND METHODS: The finite element model of thoracolumbar spines from T11 to L3 was created based on the computed tomography image of a patient with a burst fracture of the L1 vertebral body. The models of pedicular screws, rods, and locking nuts were constructed based on information from the manufacturer. Three models with different fixation configurations-that is, LS, SS, and SI-were established. The axial load was applied to the superior surface of the model. The inferior surface was fixed. The stress on each screw, rod, and vertebral body was analyzed. RESULTS: The motion of the spine in SS (0.5 mm) and SI (0.9 mm) was higher than in LS (0.2 mm). In all models, the lowest pedicle screws are the most stressed. The stress along the connecting rods was comparable between SI and LS (50 MPa). At the fracture level, stress was found at the pedicles and vertebral bodies in SI. There was relatively little stress around the fractured vertebral body in LS and SS. CONCLUSIONS: Posterior SI preserves more spinal motion than the LS. In addition, it provides favorable biomechanical properties than the SS. The stress that occurred around the pedicle screws in SI was the least among the 3 constructs, which might reduce complications such as implant failure. SI produces more stress in the fractured vertebral body than LS and SS, which could potentially aid in bone healing according to the Wolff law. CLINICAL RELEVANCE: SI has proved to be a biomechanically favorable construct and helps preserve the spinal motion segment. It could be an alternative surgical option for treating patients who present with thoracolumbar burst fractures.

Novel uniplanar pedicle screw systems applied to thoracolumbar fractures: a biomechanical study.

Objective: In this study, the advantages of the internal fixation configuration composed of uniplanar pedicle screws in the treatment of thoracolumbar fractures were verified by biomechanical experimental methods, which provided the basis for subsequent clinical experiments and clinical applications. Methods: A total of 24 fresh cadaveric spine specimens (T12-L2) were utilized to conduct biomechanical experiments. Two different internal fixation configurations, namely, the 6-screw configuration and the 4-screw/2-NIS (new intermediate screws) configuration, were tested using fixed-axis pedicle screws (FAPS), uniplanar pedicle screws (UPPS), and polyaxial pedicle screws (PAPS) respectively. The spine specimens were uniformly loaded with 8NM pure force couples in the directions of anteflexion, extension, left bending, right bending, left rotation, and right rotation, and the range of motion (ROM) of the T12-L1 and L1-L2 segments of the spine was measured and recorded to access biomechanical stability. Results: No structural damage such as ligament rupture or fracture occurred during all experimental tests. In the 6-screw configuration, the ROM of the specimens in the UPPS group was significantly better than that of the PAPS group but weaker than those of the FAPS group (p < 0.01). In the 4-screw/2-NIS configuration, the results were identical to the biomechanical test results for the 6-screw configuration (p < 0.01). Conclusion: Biomechanical test results show that the internal fixation configuration with UPPS can maintain the stability of the spine well, and the results are better than that of PAPS. UPPS has both the biomechanical advantages of FAPS and the superiority of easy operation of PAPS. We believe it is an optional internal fixation device for minimally invasive treatment of thoracolumbar fractures.

Effect of pedicle screw placement into the fractured vertebra in management of unstable thoracolumbar and lumbar fractures.

BACKGROUND: Pedicle screw insertion at the level of the fractured vertebra has been shown to improve clinical and radiological outcomes in unstable thoracolumbar and lumbar fractures, albeit this requires further evidence. The study aims to evaluate the effect of pedicle screw placement on the fractured vertebra in such cases. METHODS: A prospective study included adult patients with thoracolumbar and lumbar fractures treated with short-segment posterior instrumentation with a pedicle screw into the fractured vertebra. Anterior vertebral body height loss, kyphotic angle and degree of spinal canal compromise were measured preoperatively and postoperatively in radiographs and CT scans. The neurological status was followed up for one year of the postoperative period. RESULTS: The study included a total of 30 patients. Five patients (16.7%) had grade C, three patients (10%) had grade D, and 22 patients (73.3%) had grade E neurological status. The mean (SD) preoperative kyphotic angle, vertebral body height and canal compromise were 5.54 (5.35), 39.67% (8.04), and 31.59% (10.62), respectively. Postoperatively there was a significant canal decompression, with a mean postoperative spinal canal compromise of 5.53% (SD=7.70; p-value <0.001). At the end of one year of follow-up, the radiological evaluation showed a correction of the kyphotic angle to 6.62 (SD=2.57; p-value <0.001), and the mean anterior vertebral body height was 70.38% (SD=11.25; p-value <0.001). At the end of one year, there was a significant overall neurological recovery with a final neurological status of grade D in 5 (16.7%) and grade E in 25 patients (83.3%). There was no significant association between canal decompression and neurology at the end of the one-year follow-up. CONCLUSION: Unstable thoracolumbar and lumbar fractures surgically treated with short-segment fixation with an additional intermediate screw can achieve significant restoration of vertebral body height and correction of kyphotic angle without any added complications.

Short-Segment Fixation of Thoracolumbar Fractures with Incorporated Screws at the Level of Fracture.

OBJECTIVE: To evaluate the effect of including the fractured vertebra in the short-segment fixation of thoracolumbar (TL) fractures. METHODS: A total of 32 patients with thoraco-lumbar fractures, selected between August 2013 and February 2016, were managed by short-segment fixation with screws at the level of the fracture, and decompression was performed only for patients with neurological deficits. The patients' functional outcome was assessed using the visual analogue scale (VAS) score for pain and the American Spinal Injury Association (ASIA) score for neurological condition. All patients were followed up with radiographs. RESULTS: Patients with complete neurologic deficits (n = 3) did not show any neurologic recovery. All ASIA B patients improved to ASIA C. Five ASIA C patients improved to ASIA E. The remaining five ASIA C patients improved to ASIA D. All ASIA D patients improved to ASIA B. At the final follow-up examination, the mean anterior vertebral height was 21 ± 5 mm, indicating no significant height loss during the follow-up period. CONCLUSION: Short-segment fixation of TL fractures with inclusion of the fracture level into the construct offers good correction of segmental kyphosis, vertebral wedging, and vertebral height loss.

Effect of the short-segment internal fixation with intermediate inclined-angle polyaxial screw at the fractured vertebra on the treatment of Denis type B thoracolumbar fracture.

BACKGROUND: Short-segment internal fixation with intermediate straight-forward monoaxial screws (SSIF-SFM) and long-segment internal fixation (LSIF) are the two major surgical options for thoracolumbar (TL) fracture. However, SSIF-SFM might not provide adequate support to the spine, and LSIF is unnecessarily extensive. SSIF with intermediate inclined-angle polyxial screw (SSIF-IAP) might offer an alternative solution for the treatment of TL fracture. METHODS: A retrospective study was conducted. Sixty-nine patients (47 males and 22 females; average 34.5 years) with Denis type B TL fracture who met the criteria for inclusion were enrolled. Sagittal Cobb's angle (SCA), anterior vertebral body height (AVBH), vertebral body index (VBI), and spinal canal encroachment (SCE) were measured and assessed. Visual analogue scale (VAS) and Oswestry disability index (ODI) were also evaluated. RESULTS: The average values of incision length, blood loss, duration of operation, and hospital stay in the SSIF-IAP group and SSIF-SFM group were significantly decreased compared with those in the LSIF group. The AVBH and VBI in the SSIF-IAP group and LSIF group were significantly improved than those in the SSIF-SFM group at 6-month and the latest follow-ups (P < 0.05). The correction losses of AVBH and VBI (calculated by the reduction of AVBH and VBI) in the SSIF-IAP group and LSIF group were also significantly decreased compared with those in the SSIF-SFM group at 6-month and the latest follow-ups (P < 0.05). There was no significant difference of SCE among the three groups postoperatively. The VAS and ODI in the SSIF-IAP group and SSIF-SFM group were significantly decreased compared with those in the LSIF group at 6-month and the latest follow-ups (P < 0.05). CONCLUSION: Both SSIF-IAP and LSIF can improve the biomechanical stability as compared with SSIF-SFM. Moreover, SSIF-IAP was less extensive compared to LSIF. SSIF-IAP was an effective and reliable operative technique for patients with Denis type B TL fracture.

Which patients risk segmental kyphosis after short segment thoracolumbar fracture fixation with intermediate screws?

INTRODUCTION: The use of intermediate screws in fractured vertebrae has been proposed to decrease the number of fused levels in thoracolumbar fractures and to enable short fixations. The aim of this study was to evaluate the results of this technique and to establish predictive factors involved in loss of segmental kyphosis correction (LKC). METHODS: Forty-three patients who underwent short-segment spinal fixation with intermediate screws for a thoracolumbar spine fracture in a two-year time period were enrolled in the study. Patients had AO-type A3, A4 and B2 thoracolumbar fractures. Radiological parameters included segmental kyphosis (SK), vertebral wedge angle (VWA) and loss of anterior and posterior vertebral body height. Patients were evaluated up to one-year follow-up. The correlation between LKC and potential risk factors, such as smoking habit, sex, age, neurological status and BMI was evaluated. RESULTS: Mean preoperative SK was 16.5°±6.5°, and it decreased to 3.4°±3.5° postoperatively (P<0.01). At the one-year follow-up mean SK dropped to 5.5°±3.9° (P<0.01). Mean preoperative VWA was 20.0°±8.1°, and significantly improved to 6.3°±3.1° after surgery (P<0.01). There was a mean LKC of 1.8°±2.1°at one year. LKC mildly correlated with body mass index (BMI, r: +0.31), and obese patients (BMI>30) had an increased risk of LKC at the one-year follow-up (P=0.03; odds ratio [OR]=3.2). DISCUSSION: Analysis of the radiological data at one-year follow-up showed that all the evaluated parameters were associated with a mild loss of correction, with no impact on the clinical outcomes or implant failure. These findings confirm the trends reported in the literature. The correlation between LKC and clinical features, such as BMI, age, sex, smoking habit and preoperative neurological status was investigated. Interestingly, a positive correlation was observed between BMI and LKC, and obese patients with BMI>30 had an increased risk of LKC at one-year follow-up (OR 3.2); to our knowledge this finding has never before been reported. CONCLUSION: Short-segment fixation with intermediate screws is a viable technique with positive clinical and radiological outcomes at one-year follow-up. However, surgeons should be aware that in obese patients (BMI>30) this technique is associated with an increased risk of LKC. LEVEL OF EVIDENCE: 3.

Posterior fixation including the fractured vertebra for severe unstable thoracolumbar fractures.

BACKGROUND CONTEXT: Traditional short-segment fixation of unstable thoracolumbar injuries can be associated with progressive kyphosis and implant failure. Load sharing classification (LSC) recommends supplemental anterior reconstruction for fractures of score 7 or greater. Posterior fixation including the fractured vertebra (PFFV) has biomechanical advantages over conventional short-segment fixation. However, its efficacy in severe thoracolumbar injuries (LSC≥7) has not been studied. PURPOSE: To study the clinical, functional, and radiologic results of PFFV for severe, unstable thoracolumbar injuries (LSC≥7) at a minimum of 2 years. STUDY DESIGN: A retrospective review of case records. PATIENT SAMPLE: Thirty-two patients with an unstable burst fracture of LSC≥7 treated with PFFV were included. OUTCOME MEASURES: They included clinical outcomes: American Spinal Injury Association grade, visual analog scale (VAS), Oswestry Disability Index (ODI); and radiologic measures: segmental kyphosis angle, vertebral wedge angle, and percentage loss of anterior and posterior vertebral height. METHODS: Thirty-two patients with LSC≥7 who had undergone PFFV, with a minimum follow-up of 2 years were studied for demographic, injury, and surgical details. Clinical and radiologic outcomes were measured before surgery and at 6, 12, and 24 months postoperatively. The presence of screw breakage, screw pullout, peri-implant loosening, and rod breakage were considered as criteria for implant failure. RESULTS: None of the patients had postoperative implant failure at the final follow-up. The mean preoperative kyphosis angle was 22.9°±7.6°. This improved significantly to 9.2°±6.6° after surgery (p=.000). There was a loss of mean 2.4° (mean kyphosis angle of 11.6°±6.3°) at the final follow-up. The mean preoperative wedge angle was 23.0°±8.1°. This was corrected to 9.7°±6.2° (p=.000). There was a loss of kyphosis (mean 1.2°) in the follow-up period. The mean anterior and posterior vertebral height also showed significant improvements postoperatively, which were maintained at the final follow-up. The mean ODI and VAS scores at the end of 2 years were 17.5% and 1.6, respectively. CONCLUSIONS: Reduction of unstable thoracolumbar injuries even with LSC≥7 can be achieved and maintained with the use of short-segment pedicle screw fixation including the fractured vertebra, avoiding the need for anterior reconstruction. In the current era of evolving concepts of fracture fixation, the relevance of LSC in the management of unstable burst fractures is questionable.

Short segment pedicle screw instrumentation with an index level screw and cantilevered hyperlordotic reduction in the treatment of type-A fractures of the thoracolumbar spine.

The purpose of this study was to evaluate and compare the effect of short segment pedicle screw instrumentation and an intermediate screw (SSPI+IS) on the radiological outcome of type A thoracolumbar fractures, as judged by the load-sharing classification, percentage canal area reduction and remodelling. We retrospectively evaluated 39 patients who had undergone hyperlordotic SSPI+IS for an AO-Magerl Type-A thoracolumbar fracture. Their mean age was 35.1 (16 to 60) and the mean follow-up was 22.9 months (12 to 36). There were 26 men and 13 women in the study group. In total, 18 patients had a load-sharing classification score of seven and 21 a score of six. All radiographs and CT scans were evaluated for sagittal index, anterior body height compression (%ABC), spinal canal area and encroachment. There were no significant differences between the low and high score groups with respect to age, duration of follow-up, pre-operative sagittal index or pre-operative anterior body height compression (p = 0.217, 0.104, 0.104, and 0.109 respectively). The mean pre-operative sagittal index was 19.6° (12° to 28°) which was corrected to -1.8° (-5° to 3°) post-operatively and 2.4° (0° to 8°) at final follow-up (p = 0.835 for sagittal deformity). No patient needed revision for loss of correction or failure of instrumentation. Hyperlordotic reduction and short segment pedicle screw instrumentation and an intermediate screw is a safe and effective method of treating burst fractures of the thoracolumbar spine. It gives excellent radiological results with a very low rate of failure regardless of whether the fractures have a high or low load-sharing classification score.

Biomechanical efficacy of monoaxial or polyaxial pedicle screw and additional screw insertion at the level of fracture, in lumbar burst fracture: An experimental study.

BACKGROUND: Use of a pedicle screw at the level of fracture, also known as an intermediate screw, has been shown to improve clinical results in managing lumbar fracture, but there is a paucity of biomechanical studies to support the claim. The aim of this study was to evaluate the effect of adding intermediate pedicle screws at the level of a fracture on the stiffness of a short-segment pedicle fixation using monoaxial or polyaxial screws and to compare the strength of monoaxial and polyaxial screws in the calf spine fracture model. MATERIALS AND METHODS: Flexibility of 12 fresh-frozen calf lumbar spine specimens was evaluated in all planes. An unstable burst fracture model was created at the level of L3 by the pre-injury and dropped-mass technique. The specimens were randomly divided into monoaxial pedicle screw (MPS) and polyaxial pedicle screw (PPS) groups. Flexibility was retested without and with intermediate screws (MPSi and PPSi) placed at the level of fracture in addition to standard screws placed at L2 and L4. RESULTS: The addition of intermediate screws significantly increased the stability of the constructs, as measured by a decreased range of motion (ROM) in flexion, extension, and lateral bending in both MPS and PPS groups (P < 0.05). There was neither any significant difference in the ROM in the spines of the two groups before injury, nor a difference in the ROM between the MPSi and PPSi groups (P > 0.05), but there was a significant difference between MPS and PPS in flexion and extension in the short-segment fixation group (P < 0.05). CONCLUSIONS: The addition of intermediate screws at the level of a burst fracture significantly increased the stability of short-segment pedicle screw fixation in both the MPS and PPS groups. However, in short-segment fixation group, monoaxial pedicle screw exhibited more stability in flexion and extension than the polyaxial pedicle screw.