Comparative clinical efficacy and safety of cortical bone trajectory screw fixation and traditional pedicle screw fixation in posterior lumbar fusion: a systematic review and meta-analysis

[Comparison of Clinical Effects of Cortical Bone Trajectory Screws and Traditional Pedicle Screws in Posterior Lumbar Fusion]

Objective

To compare the clinical effects of cortical bone trajectory screws and traditional pedicle screws in posterior lumbar fusion.

Methods

A retrospective study was conducted to analyze lumbar degeneration patients who underwent surgical treatment at our hospital between January 2016 and January 2019. A total of 123 patients who met the inclusion criteria were enrolled. The subjects were divided into two groups according to their surgical procedures and the members of the two groups were matched by age, sex, and the number of fusion segments. There were 63 patients in the traditional pedicle screws (PS) group and 60 in the cortical bone trajectory screws (CBTS) group. The outcomes of the two groups were compared. The primary outcome measures were perioperative conditions, including operation duration, estimated intraoperative blood loss (EBL), and length-of-stay (LOS), visual analog scale (VAS) score, Oswestry Disability Index (ODI) score, and interbody fusion rate. The secondary outcome measures were the time to postoperative ambulation and the incidence of complications. VAS scores and ODI scores were assessed before operation, 1 week, 1 month, 3 months, and 12 months after operation, and at the final follow-up. The interbody fusion rate was assessed in 1 year and 2 years after the operation and at the final follow-up.

Results

The CBTS group showed a reduction in operation duration ([142.8±13.1] min vs. [174.7±15.4] min, P<0.001), LOS ([9.5±1.5] d vs. [12.0±2.0] d, P<0.001), and EBL ([194.2±38.3] mL vs. [377.5±33.1] mL, P<0.001) in comparison with the PS group. The VAS score for back pain in the CBTS group was lower than that in the PS group at 1 week and 1 month after operation and the ODI score in the CBTS group was lower than that in the PS group at 1 month after operation, with the differences being statistically significant (P<0.05). At each postoperative time point, the VAS score for leg pain and the interbody fusion rate did not show significant difference between the two groups. The VAS score for back and leg pain and the ODI score at each time point after operation in both the CBTS group and the PS group were significantly lower than those before operation (P<0.05). No significant difference was found in the time to postoperative ambulation or the overall complication incidence between the two groups.

Conclusion

The CBTS technique could significantly shorten the operation duration and LOS, reduce EBL, and achieve the same effect as the PS technique does in terms of intervertebral fusion rate, pain relief, functional improvement, and complication incidence in patients undergoing posterior lumbar fusion.

Comparison of the clinical and radiographic outcomes of cortical bone trajectory and traditional trajectory pedicle screw fixation in transforaminal lumbar interbody fusion: a randomized controlled trial

PURPOSE

To compare the clinical outcomes and radiographic outcomes of cortical bone trajectory (CBT) and traditional trajectory (TT) pedicle screw fixation in patients treated with single-level transforaminal lumbar interbody fusion (TLIF).

METHODS

This trial included a total of 224 patients with lumbar spine disease who required single-level TLIF surgery. Patients were randomly assigned to the CBT and TT groups at a 1:1 ratio. Demographics and clinical and radiographic data were collected to evaluate the efficacy and safety of CBT and TT screw fixation in TLIF.

RESULTS

The baseline characteristic data were similar between the CBT and TT groups. Back and leg pain for both the CBT and TT groups improved significantly from baseline to 24 months postoperatively. The CBT group experienced less pain than the TT group at one week postoperatively. The postoperative radiographic results showed that the accuracy of screw placement was significantly increased in the CBT group compared with the TT group (P < 0.05). The CBT group had a significantly lower rate of FJV than the TT group (P < 0.05). In addition, the rate of fusion and the rate of screw loosening were similar between the CBT and TT groups according to screw loosening criteria.

CONCLUSION

This prospective, randomized controlled analysis suggests that clinical outcomes and radiographic characteristics, including fusion rates and caudal screw loosening rates, were comparable between CBT and TT screw fixation. Compared with the TT group, the CBT group showed advantages in the accuracy of screw placement and the FJV rate.

CLINICAL TRIALS REGISTRATION

This trial has been registered at the US National Institutes of Health Clinical Trials Registry: NCT03105167.

Effectiveness and safety of robot-assisted versus fluoroscopy-assisted cortical bone trajectory screw instrumentation in spinal surgery: a systematic review and meta-analysis

Robot-assisted (RA) technology has been shown to be a safe aid in spine surgery, this meta-analysis aims to compare surgical parameters and clinical indexes between robot-assisted cortical bone trajectory (CBT) and fluoroscopy-assisted (FA) cortical bone trajectory in spinal surgery. We searched databases such as PubMed, Web of Science, the Cochrane Library, and the China National Knowledge Infrastructure. The study selection process was guided by the PICOS (Patient/Problem, Intervention, Comparison, Outcome, Study Design) strategy. The risk of bias in non-randomized comparative studies was assessed using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool. We performed this meta-analysis using RevMan 5.3 software (Cochrane Collaboration, Copenhagen, Denmark), and the level of statistical significance was set at P < 0.05. Six articles involving 371 patients and 1535 screws were included in this meta-analysis. RA-CBT outperformed FA-CBT in terms of various parameters, such as accuracy of pedicle screw position (both Gertzbein-Robbins scale and Ding scale), avoidance of superior facet joint violation (FJV), and reduction of neurological injury. Our meta-analysis offered a thorough evaluation of the efficacy and safety of RA-CBT in spinal surgery. The findings revealed that RA-CBT produced statistically significant results in terms of pedicle screw position accuracy and superior facet joint violation prevention. In terms of surgical parameters and clinical indexes, future research and clinical practice should investigate the efficacy of RA-CBT further. The study was registered in the PROSPERO (CRD42023466280).

Comparing Cortical Bone Trajectory and Traditional Pedicle Screws in Transforaminal Lumbar Interbody Fusion: A Retrospective Cohort Study of One-Year Outcomes

INTRODUCTION

This is a retrospective study of consecutive patients undergoing transforaminal lumbar interbody fusion (TLIF) at a single institution. The objective of this study was to compare the long-term results associated with cortical bone trajectory (CBT) and traditional pedicle screw (TPS) via posterolateral approach in TLIF.

METHODS

Consecutive patients treated from November 2014 to March 2019 were included in the CBT TLIF group, while consecutive patients treated from October 2010 to August 2017 were included in the TPS TLIF group. Inclusion criteria comprised single-level or two-level TLIF for degenerative spondylolisthesis with stenosis and at least one year of clinical and radiographic follow-up. Variables of interest included pertinent preoperative, perioperative, and postoperative data. Non-parametric evaluation was performed using the Wilcoxon test. Fisher's exact test was used to assess group differences for nominal data.

RESULTS

Overall, 140 patients met the inclusion criteria; 69 patients had CBT instrumentation (mean follow-up 526 days) and 71 patients underwent instrumentation placement via TPS (mean follow-up 825 days). Examination of perioperative and postoperative outcomes demonstrate comparable results between the groups with perioperative complications, length of stay, discharge destination, surgical revision rate, and fusion rates all being similar between groups (p = 0.1; p = 0.53; p = 0.091; p = 0.61; p = 0.665, respectively).

CONCLUSIONS

CBT in the setting of TLIF offer equivalent outcomes to TPS with TLIF at both short- and long-term intervals of care.

Complication, fusion, and revision rate in the lumbar cortical bone trajectory and pedicle screw fixation techniques: a systematic review and meta-analysis

BACKGROUND

To obtain the complication rate, fusion rate, and revision rate of the lumbar cortical bone trajectory technique and pedicle screw fixation technique in lumbar interbody fusion surgery by single-arm meta-analysis and lay a basis for orthopedic surgeons to select the fixation techniques and perioperative management.

METHODS

PubMed, Ovid Medline, Web of Science, CNKI, and Wanfang databases were searched comprehensively. Data extraction, content analysis, and quality assessment of the literature were performed by two independent reviewers according to the Cochrane Collaboration guidelines using R and STATA software for single-arm meta-analysis.

RESULTS

The total complication rate of the lumbar cortical bone trajectory technique was 6%, including a hardware complication rate of 2%, ASD (adjacent segment degeneration) rate of 1%, wound infection rate of 1%, dural damage rate of 1%, hematoma rate tending to 0%, fusion rate of 94%, and revision rate of 1%. Lumbar pedicle screw fixation techniques had a total complication rate of 9%, with a hardware complication rate of 2%, ASD rate of 3%, wound infection rate of 2%, dural damage rate of 1%, hematoma rate tending to 0%, fusion rate of 94%, and revision rate of 5%. This study was registered with PROSPERO, CRD42022354550.

CONCLUSION

Lumbar cortical bone trajectory was associated with a lower total complication rate, ASD rate, wound infection rate, and revision rate than pedicle screw fixation. The cortical bone trajectory technique reduces the incidence of intraoperative and postoperative complications and can be an alternative in lumbar interbody fusion surgery.

Avoiding Spinal Implant Failures in Osteoporotic Patients: A Narrative Review

STUDY DESIGN

Narrative review.

OBJECTIVES

With an aging population, the prevalence of osteoporosis is continuously rising. As osseous integrity is crucial for bony fusion and implant stability, previous studies have shown osteoporosis to be associated with an increased risk for implant failure and higher reoperation rates after spine surgery. Thus, our review's purpose was to provide an update of evidence-based solutions in the surgical treatment of osteoporosis patients.

METHODS

We summarize the existing literature regarding changes associated with decreased bone mineral density (BMD) and resulting biomechanical implications for the spine as well as multidisciplinary treatment strategies to avoid implant failures in osteoporotic patients.

RESULTS

Osteoporosis is caused by an uncoupling of the bone remodeling cycle based on an unbalancing of bone resorption and formation and resulting reduced BMD. The reduction in trabecular structure, increased porosity of cancellous bone and decreased cross-linking between trabeculae cause a higher risk of complications after spinal implant-based surgeries. Thus, patients with osteoporosis require special planning considerations, including adequate preoperative evaluation and optimization. Surgical strategies aim towards maximizing screw pull-out strength, toggle resistance, as well as primary and secondary construct stability.

CONCLUSIONS

As osteoporosis plays a crucial role in the fate of patients undergoing spine surgery, surgeons need to be aware of the specific implications of low BMD. While there still is no consensus on the best course of treatment, multidisciplinary preoperative assessment and adherence to specific surgical principles help reduce the rate of implant-related complications.

Comprehensive comparison of three techniques for the treatment of adjacent segment degeneration after lumbar fusion

Purpose

Adjacent segment degeneration (ASD) following lumbar fusion is technically challenging for spine surgeons. Posterolateral open fusion surgery with pedicle screw fixation is an effective way to treat symptomatic ASD with favorable clinical outcomes; however, it is associated with an increased morbidity rate. Therefore, minimally invasive spine surgery is advocated. This study was designed to compare clinical outcomes among patients with symptomatic ASD who underwent percutaneous transforaminal endoscopic discectomy (PTED) with the transforaminal approach, posterior lumbar interbody fusion (PLIF) with cortical bone trajectory screw fixation (CBT-PLIF), and PLIF with traditional trajectory screw fixation (TT-PLIF).

Methods

A retrospective study was conductedon 46 patients (26 men and 20 women; average age 60.8 ± 6.78 years) with symptomatic ASD. The patients were treated with three approaches. The operation time, incision length, time to return to work, complications, and the like were compared among three groups. Intervertebral disc (IVD) space height, angular motion, and vertebral slippage were obtained to assess spine biomechanical stability following surgery. The visual analog scale (VAS) score and Oswestry disability index were evaluated at preoperation and 1-week, 3-month, and the latest follow-ups. Clinical global outcomes were also estimated using modified MacNab criteria.

Results

The operation time, incision length, intraoperative blood loss, and time to return to work for the PTED group were significantly decreased compared with those for the other two groups (P &lt; 0.05). The radiological indicators in the CBT-PLIF group and TT-PLIF group had better biomechanical stability compared with those in the PTED groups at the latest follow-up (P &lt; 0.05). The back pain VAS score in the CBT-PLIF group was significantly decreased compared with those in the other two groups at the latest follow-up (P &lt; 0.05). The good-to-excellent rate was 82.35% in the PTED group, 88.89% in the CBT-PLIF group, and 85.00% in the TT-PLIF group. No serious complications were encountered. Two patients experienced dysesthesia in the PTED group; screw malposition was found in one patient in the CBT-PLIF group. One case with a dural matter tear was observed in the TT-PLIF group.

Conclusion

All three approaches can treat patients with symptomatic ASD efficiently and safely. Functional recovery was more accelerated in the PTED group compared with the other approaches in the short term; CBT-PLIF and TT-PLIF can provide superior biomechanical stability to the lumbosacral spine following decompression compared with PTED; however, compared with TT-PLIF, CBT-PLIF can significantly reduce back pain caused by iatrogenic muscle injury and improve functional recovery. Therefore, superior clinical outcomes were achieved in the CBT-PLIF group compared with the PTED and TT-PLIF groups in the long term.

[Application of navigation in the fractured spine]

OBJECTIVE

Computer navigation is used in patients with spine fractures to optimize the accuracy of pedicle screws and thereby reduce intra- and postoperative complications, such as injuries to vessels, nerves and accompanying structures. In addition, the ideal screw length and diameter for each pedicle can be detected to ensure optimal stability.

INDICATIONS

Intraoperative navigation is suitable for the treatment of spine fractures, which require dorsal stabilization or fusion. It is primarily used for dorsal procedures ranging from the cervical to lumbar/sacral spine.

CONTRAINDICATIONS

Computer navigation relies on rigid fixation of the dynamic reference base (DRB) at the spinous process. Failure of DRB fixation is the major contraindication for navigation in the spine.

SURGICAL TECHNIQUE

After acquisition of an intraoperative three-dimensional (3D) scan, a digital relation between the anatomy and the 3D scan is established with the navigation system and its infrared camera. Pedicle screws are planned percutaneously with a calibrated pointer. In the next step K‑wires (or screws) are implanted after the pedicles are drilled with a calibrated drill guide. After implantation, an additional 3D scan is performed to verify accurate K‑wire placement.

POSTOPERATIVE MANAGEMENT

Postoperative management does not differ compared to nonnavigated procedures.

RESULTS

Intraoperative navigation in combination with modern imaging systems leads to very high accuracy for pedicle screws. Immediate intraoperative control of K‑wires as well as screws and fracture reduction can avoid revision surgery. Image guidance can reduce radiation exposure for the surgical team.

Midline Lumbar Fusion Versus Posterior Lumbar Interbody Fusion Involving L5-S1 For Degenerative Lumbar Diseases: A Comparative Study

BACKGROUND

A retrospective cohort study to evaluate the efficacy and safety of midline lumbar fusion (MIDLF) for lumbosacral fusion compared to posterior lumbar interbody fusion (PLIF).

METHODS

Patients who had undergone posterior lumbosacral fusion surgery were divided into a MIDLF group (n = 37) and a PLIF group (n = 42). The follow-up time was at least 12 months. The operation data, recovery condition, complications, clinical outcomes, and status of implants and fusion were compared between the 2 groups.

RESULTS

The MIDLF group experienced significantly less blood loss, lower postoperative creatine kinase levels and total drainage volume, earlier time to ambulation, and less hospital stay times after surgery compared to the PLIF group (P < 0.05). The mean postoperative back pain visual analog scale scores in the MIDLF group were significantly lower than the PLIF group (P < 0.05). The improvement in Oswestry Disability Index scores during 3-month follow-up displayed a significant difference between the 2 groups (P < 0.05). The fusion rate tended to be higher in the MIDLF group; however, the difference was not significant (P > 0.05). There was no significant difference in respect to screw loosening and cage subsidence rate. There were 2 cases of complications both occurring in the PLIF group.

CONCLUSIONS

MIDLF is safe and effective for lumbosacral fusion and in line with the concept of enhanced recovery after surgery.

Cortical Bone Trajectory Pedicle Screw Fixation in Surgical Treatment of Monosegmental Pyogenic Lumbar Spondylodiskitis

BACKGROUND AND STUDY OBJECT

 Pedicle screw fixation has been widely used in surgical treatment for infective lumbar spondylodiskitis to prevent instability and deformity. The cortical bone trajectory pedicle screw (CBTPS) fixation is a minimally invasive posterior spinal fixation system that runs from the pedicle's entry point of the caudiomedial region toward the cephalad-divergent direction. Successful results with CBTPS fixation have been reported to treat degenerative and osteoporotic spinal diseases. This study aims to investigate the clinical feasibility of CBTPS in the surgical treatment of pyogenic lumbar spondylodiskitis.

PATIENT AND METHODS

 We retrospectively retrieved 20 consecutive patients from two academic centers who were surgically treated for monosegmental lumbar pyogenic spondylodiskitis. The primary surgical treatment was the anterior lumbar interbody fusion with decompression, debridement, and reconstruction using an autogenous iliac strut bone graft. One to 2 weeks after the primary surgery, patients underwent a second surgery for posterior instrumentation using conventional pedicle screws (CPS; group I) and CBTPS (group II). Radiographic parameters of the deformity angle at the fusion segment and clinical parameter of visual analog scale (VAS) scores were assessed preoperatively, postoperatively, and at the last follow-up.

RESULTS

 There were 10 patients in each group. The mean follow-up periods of groups I and II were 51.10 ± 6.95 and 28.60 ± 9.31 months, respectively. Intergroup analysis indicated the two groups area age-matched (p = 0.38), but initial C-reactive protein (CRP; mg/dL, p = 0.04), CRP normalization (months, p = 0.00), and follow-up duration (months, p = 0.00) were heterogeneous. Meanwhile, deformity angles (segmental lordosis) between the two groups were not significantly different preoperatively (p = 0.25), postoperatively (p = 0.13), and at last follow-up (p = 0.38). The intragroup analysis indicated a significant postoperative increase of lordosis in both group I and II (p = 0.00 and 0.04, respectively) with subsequent subsidence. Lordosis remained increased at the last follow-up with or without significance (group I, p = 0.02; group II, p = 0.62). Both groups showed significant improvement in VAS scores (group I, p = 0.00; group II, p = 0.00).

CONCLUSION

 In monosegmental lumbar spondylodiskitis, posterior stabilization of the anterior strut bone graft by CBTPS and CPS was comparable via the radiographic parameter of segmental lordosis or deformity angle. Our observation suggests the clinical feasibility of CBTPS in the treatment of relatively mild monosegmental pyogenic lumbar spondylodiskitis.

Biomechanical comparison of pedicle screw fixation strength among three different screw trajectories using single vertebrae and one-level functional spinal unit

Three key factors are responsible for the biomechanical performance of pedicle screw fixation: screw mechanical characteristics, bone quality and insertion techniques. To the best of the authors' knowledge, no study has directly compared the biomechanical performance among three trajectories, i.e., the traditional trajectory (TT), modified trajectory (MT) and cortical bone trajectory (CBT), in a porcine model. This study compared the pullout strength and insertion torque of three trajectory methods in single vertebrae, the pullout strength and fixation stiffness including flexion, extension, and lateral bending in a one-level instrumented functional spinal unit (FSU) that mimics the in vivo configuration were clarified. A total of 18 single vertebrae and 18 FSUs were randomly assigned into three screw insertion methods (n = 6 in each trajectory group). In the TT group, the screw converged from its entry point, passed completely inside the pedicle, was parallel to the superior endplate, was located in the superior third of the vertebral body and reached to at least the anterior third of the vertebral body. In the MT group, the convergent angle was similar to that of the TT method but directed caudally to the anterior inferior margin of the vertebral body. The results of insertion torque and pullout strength in single vertebrae were analyzed; in addition, the stiffness and pullout strength in the one-level FSU were also investigated. This study demonstrated that, in single vertebrae, the insertion torque was significantly higher in CBT groups than in TT and MT groups (p < 0.05). The maximal pullout strength was significantly higher in MT groups than in TT and CBT groups (p < 0.05). There was no significant difference in stiffness in the three motions among all groups. The maximal pullout strength in FSUs of MT and CBT groups were significantly higher than the TT groups (p < 0.05). We concluded that either MT or CBT provides better biomechanical performance than TT in single vertebrae or FSUs. The lack of significance of stiffness in FSUs among three methods suggested that MT or CBT could be a reasonable alternative to TT if the traditional trajectory was not feasible.

Anatomical and Imaging Study on the Optimum Entry Point and Trajectory for Anterior Transpedicular Root Screw Placement into the Lower Cervical Spine

Objective

To study the optimum entry point and trajectory for anterior transpedicular root screw (ATPRS) placement into the lower cervical spine (LCS), so as to provide a basis for clinical application.

Methods

A retrospective analysis of cervical CT images of patients who underwent cervical CT examination in the Spinal Surgery of Ningbo No. 6 Hospital from January 2020 to August 2021 was conducted. The data were obtained and modeled. On the coronal plane, the vertebral body (VB) between the anterior midline of cervical vertebral segments C_3-7 and the left P line (by drawing the line parallel to the anterior midline of the VB at the intersection of the anterior edge of the Luschka's joint and the upper endplate) was equally divided into 9 zones (a-i). The ideal entry point and path of cervical ATPRS were designed and recorded. Additionally, 7 cadaveric specimens were selected, and the screw placement parameters were regenerated according to the above methods for screw placement.

Results

Zone i of each segment, with the longest screw length, was the best area for screw placement. In all patients, the horizontal angles of vertebrae C_3-7 in zones a, d, and g, zones b, e, and h, and zones c, f, and i showed a gradually decreasing trend. The sagittal angle range of C_3-7 in all patients showed a gradually increasing trend in zones a-c, d-f, and g-i. The distance from the anterior midline of C_3-7 to the P line increased in all patients, and the distance was longer in males than in females, with statistical significance. Pedicle screws were successfully inserted in all the 7 cadaveric specimens.

Conclusions

ATPRS placement can be used for LCS internal fixation, and the precise screw placement parameters can be simulated by the software, which provides theoretical basis for its future clinical application.

Postoperative Spinal Implant Infections (PSII)-A Systematic Review: What Do We Know So Far and What is Critical About It?

STUDY DESIGN

Systematic review.

OBJECTIVES

Postoperative spinal implant infections (PSII) are an increasing challenge in the daily clinical routine. This review summarizes existing knowledge in the field of PSII, including definitions, epidemiology, classifications, risk factors, pathogenesis, symptoms, diagnosis, and treatment.

METHODS

A systematic review was performed using a structured PubMed analysis, based on the PRISMA criteria. The search terminology was set as: "spinal implant associated infection OR spinal implant infection OR spinal instrumentation infection OR peri spinal implant infection." PubMed search was limited to the categories randomized controlled trials (RCT), clinical trials, meta-analysis and (systematic) reviews, whereas case reports were excluded. Studies from January 2000 to December 2020 were considered eligible. A total of 572 studies were identified, 82 references included for qualitative synthesis, and 19 for detailed sub analysis (12 meta-analysis, 7 prospective RCT).

RESULTS

Structural problems in the field of PSII were revealed, including (1) limited level of evidence in clinical studies (missing prospective RCT, metanalyzes), (2) small patient numbers, (3) missing standardized definitions, (4) heterogeneity in patient groups, and (5) redundancy in cited literature.

CONCLUSION

Evidence-based knowledge about spinal implant-associated infections is lacking. All involved medical fields should come together to define the term PSII and to combine their approaches toward research, training, and patient care.

Comparative outcomes of cortical bone trajectory screw fixation and traditional pedicle screws in lumbar fusion: A meta-analysis

BACKGROUND

Pedicular screws (PS) is often used in lumbar fusion. Cortical bone trajectory (CBT) is a novel technology in lumbar fusion with less clinical outcomes evidence. So we conduct a meta-analysis to compare the efficacy and safety between cortical bone trajectory screw fixation and traditional pedicle screws in lumbar fusion surgery.

METHODS

Multiple databases were searched for the articles about comparison of cortical bone trajectory (CBT) and traditional pedicle screws (PS) in lumbar fusion surgeries. The Meta-analysis was conducted by Revman 5.3 software. The following indicators were abstracted: visual analog scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI), Japanese Orthopedic Association (JOA), surgical duration, complications, and blood loss. The quality of the articles was assessed by the Newcastle-Ottawa Scale or Cochrane Handbook.

RESULTS

25 studies were included involving a total of 1735 patients. There is no difference in preoperative VAS scores, JOA, ODI, postoperative VAS scores and fusion rates. Besides, postoperative JOA(MD = 0.78, P = 0.02), ODI (MD = -2.09, P＝0.03), surgical duration(MD = -26.90, P = 0.02), complications(MD = 0.70, P = 0.03), and blood loss(MD = -85.27, P＝0.0009) showed greater improvement trends in CBT group than PS group with significant difference.

CONCLUSION

CBT reduced the rate of complications, surgical duration, blood loss, postoperative ODI and JOA scores. CBT technique with better postoperative outcomes achieved similar fusion rates compared with PS technique.

Predictors of adverse events after percutaneous pedicle screws fixation in patients with single-segment thoracolumbar burst fractures

BACKGROUND

Percutaneous pedicle screw fixation (PPSF) is the primary approach for single-segment thoracolumbar burst fractures (TLBF). The healing angle at the thoracolumbar junction is one of the most significant criteria for evaluating the efficacy of PPSF. Therefore, the purpose of this study was to analyze the predictors associated with the poor postoperative alignment of the thoracolumbar region from routine variables using a support vector machine (SVM) model.

METHODS

We retrospectively analyzed patients with TLBF operated at our academic institute between March 1, 2014 and December 31, 2019. Stepwise logistic regression analysis was performed to assess potential statistical differences between all clinical and radiological variables and the adverse events. Based on multivariate logistic results, a series of independent risk factors were fed into the SVM model. Meanwhile, the feature importance of radiologic outcome for each parameter was explored. The predictive performance of the SVM classifier was evaluated using the area under the receiver operating characteristic curve (AUC), accuracy (ACC) and confusion matrices with 10-fold cross-validation, respectively.

RESULTS

In the recruited 150 TLBFs, unfavorable radiological outcomes were observed in 53 patients (35.33%). The relationship between osteoporosis (p = 0.036), preoperative Cobb angle (p = 0.001), immediate postoperative Cobb angle (p = 0.029), surgically corrected Cobb angle (p = 0.001), intervertebral disc injury (Score 2 p = 0.001, Score 3 p = 0.001), interpedicular distance (IPD) (p = 0.001), vertebral body compression rate (VBCR) (p = 0.010) and adverse events was confirmed by univariate regression. Thereafter, independent risk factors including preoperative Cobb angle, the disc status and IPD and independent protective factors surgical correction angle were identified by multivariable logistic regression. The established SVM classifier demonstrated favorable predictive performance with the best AUC = 0.93, average AUC = 0.88, and average ACC = 0.87. The variables associated with radiological outcomes, in order of correlation strength, were intervertebral disc injury (42%), surgically corrected Cobb angle (25%), preoperative Cobb angle (18%), and IPD (15%). The confusion matrix reveals the classification results of the discriminant analysis.

CONCLUSIONS

Critical radiographic indicators and surgical purposes were confirmed to be associated with an unfavorable radiographic outcome of TLBF. This SVM model demonstrated good predictive ability for endpoints in terms of adverse events in patients after PPSF surgery.

Cortical Trajectory Fixation Versus Traditional Pedicle-Screw Fixation in the Treatment of Lumbar Degenerative Patients with Osteoporosis: A Prospective Randomized Controlled Trial

Study Design

Objective

Methods

Results

Conclusion

Trial Registration Number

Date of Registration

Multivariate analysis of pedicle screw invasion of the proximal facet joint after lumbar surgery

BACKGROUND

To analyze the risk factors for pedicle screw invasion of the proximal facet joint after lumbar surgery.

METHODS

From January 2019 to January 2021, 1794 patients with lumbar degenerative disease, such as lumbar disc herniation, lumbar spinal stenosis and lumbar spondylolisthesis, were treated at our hospital. In all, 1221 cases were included. General data (sex, age, BMI), bone mineral density, proximal facet joint angle, degenerative lumbar spondylolisthesis, isthmic lumbar spondylolisthesis and fixed segment in the two groups were recorded. After the operation, vertebral CT of the corresponding surgical segments was performed for three-dimensional reconstruction and evaluation of whether the vertebral arch root screw interfered with the proximal facet joint. The included cases were divided into an invasion group and a noninvasion group. Univariate analysis was used to screen the risk factors for pedicle screw invasion of the proximal facet joint after lumbar surgery, and the selected risk factors were included in the logistic model for multivariate analysis.

RESULTS

The single-factor analysis showed a significant difference in age, BMI, proximal facet joint angle, degenerative lumbar spondylolisthesis, and fixed segment (P < 0.1). Multifactor analysis of the logistic model showed a significant difference for age ≥ 50 years (P < 0.001, OR = 2.291), BMI > 28 kg/m2 (P < 0.001, OR = 2.548), degenerative lumbar spondylolisthesis (P < 0.001, OR = 2.187), gorge cleft lumbar relaxation (P < 0.001, OR = 2.410), proximal facet joint angle (35 ~ 45°: P < 0.001, OR = 3.151; > 45°: P < 0.001, OR = 3.578), and fixed segment (lower lumbar spine: P < 0.001, OR = 2.912).

CONCLUSION

Age (≥ 50 years old), BMI (> 28 kg/m2), proximal facet joint angle (35 ~ 45°, > 45°), degenerative lumbar spondylolisthesis, isthmic lumbar spondylolisthesis and fixed segment (lower lumbar spine) are independent risk factors for pedicle screw invasion of the proximal facet joint after lumbar surgery. Compared with degenerative lumbar spondylolisthesis, facet joint intrusion is more likely in isthmic lumbar spondylolisthesis.

Cortical-bone-trajectory-based dynamic stabilization

BACKGROUND

Cortical-bone-trajectory (CBT) screws have demonstrated similar biomechanical strength and fusion rates as conventional pedicle screws for short-segment lumbar fusion. However, very few studies have verified the viability of CBT screws in dynamic stabilization.

OBJECTIVE

To compare the clinical outcomes of CBT-based Dynesys dynamic stabilization (CBT-DDS) with standard minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

METHODS

Consecutive patients who received CBT-DDS or MI-TLIF at L4-5 or L3-4-5 were retrospectively reviewed. All the radiological and clinical outcomes were compared between the two groups. The patient-reported outcomes (PRO) included visual analog scales of back and leg pain, Japanese Orthopaedic Association Scores, and the Oswestry Disability Index. The pre- and post-operative radiological evaluations were also reviewed.

RESULTS

A total of 60 patients (20 patients of the CBT-DDS and 40 of the MI-TLIF groups) were analyzed. The MI-TLIF group had a longer operation time (p=0.010) than the CBT-DSS group, but with similar estimated blood loss (p=0.484). Perioperative complications, including screw loosening, wound infection and radiculopathy, were similar in both groups (all p>0.05). The degree of decreased range of motion after surgery was similar between the two groups (p=0.781), and there was no pseudarthrosis in the MI-TLIF group.

CONCLUSION

Since the clinical and radiologic outcomes of CBT-DDS were similar to that of MI-TLIF in patients of L4-5 or L3-4-5 spondylosis and spondylolisthesis, CBT-DDS appeared to be a viable and effective alternative to MI-TLIF, and with less operation time and similarly limited segmental motility.

The Rates and Risk Factors of Intra-Pedicular Accuracy and Proximal Facet Joint Violation for Single-Level Degenerative Lumbar Diseases: Cortical Bone Trajectory Versus Traditional Trajectory Pedicle Screw

STUDY DESIGN

A retrospective study.

OBJECTIVE

To compare the accuracy of pedicle screw placement and proximal facet joint violation (FJV) in single-level degenerative lumbar diseases using cortical bone trajectory (CBT) and traditional trajectory (TT) techniques, and analyze their possible risk factors.

SUMMARY OF BACKGROUND DATA

CBT screws have been utilized increasingly to improve cortical bone contact to prevent screw pullout and reduce approach-related morbidity. However, the studies on intra-pedicular accuracy and proximal FJV between the two methods are rare.

METHODS

A total of 40 patients who required single-level instruments were included in the retrospective study treated with the CBT-TLIF and the TT-TLIF at a 1:1 ratio from March 2019 to August 2020. The radiographic outcomes were the intra-pedicular accuracy and proximal FJV. Moreover, the possible risk factors were assessed using bivariate and multivariate analyses.

RESULTS

As for the intra-pedicular accuracy, 73 screws (91.3%) were classified as grade A, 7 screws (8.7%) classified as grade B in the CBT group. A total of 71 screws (88.8%) were graded A with remaining 8 screws (10.0%) graded B and 1 screw (1.2%) graded C in the TT group. The proportion of optimal and clinically acceptable screw positions in the two groups were not significantly different (P > 0.05). In addition, the rate of proximal FJV in CBT approach (8.3%) was significantly lower than that in the TT approach (35.0%) (P < 0.001). Multivariate analysis showed the TT insertion approach and facet angle ≥45° were the independent risk factors for proximal FJV, but no factors above affected intra-pedicular accuracy.

CONCLUSION

Compared with the TT approach in TLIF, the CBT approach showed similar intra-pedicular accuracy and remarkable superiority in proximal facet joint protection. Facet angle ≥45° is the independent risk factors for proximal FJV.Level of Evidence: 2.

Biomechanical Evaluation of Cortical Bone Trajectory Fixation with Traditional Pedicle Screw in the Lumbar Spine: A Finite Element Study

Cortical bone trajectory (CBT) is increasingly used in spinal surgery. Although there are many biomechanical studies, the biomechanical effect of CBT in combination with traditional pedicle screws is not detailed. Therefore, the purpose of this study was to investigate the effects of the traditional pedicle screw and CBT screw implantation on the lumbar spine using finite element methods. Based on the combination of the traditional pedicle screw and the CBT system implanted into the lumbar spine, four finite element spinal lumbar models were established. The models were given four different load conditions (flexion, extension, lateral bending, and axial rotation), and the deformation and stress distribution on the finite element model were observed. The results show that there was no significant difference in the structural stability of the lumbar spine model between the traditional pedicle screw system and the CBT system. In addition, CBT may reduce stress on the endplate. Different movements performed by the model may have significant biomechanical effects on the spine and screw system. Clinical spinal surgeons may also consider using the CBT system in revision spinal surgery, which may contribute to smaller wounds.

Long-Term Outcome After Midline Lumbar Fusion for the Treatment of Lumbar Spine Instability Due to Degenerative Disease

BACKGROUND

Midline lumbar fusion (MIDLF) is one promising new surgical technique that has been developed to minimize perioperative damage to the paravertebral stabilizing musculotendinous system. The aim of this study was to assess long-term clinical and radiological effects of MIDLF.

METHODS

This prospective cohort study evaluated patients who underwent MIDLF for degenerative spinal instability. Clinical and radiological examinations were performed before and after surgery. Perioperative and postoperative complications were recorded. Follow-up was 2 years. P ≤ 0.05 was considered statistically significant.

RESULTS

The study included 64 patients (mean age 58.9 ± 10.7 years; 41 women [64.1%]). The most frequent indication for MIDLF was degenerative spondylolisthesis grade I (28 cases [43.8%]); the prevalent spinal segment to be fused was L4-L5 (35 cases [54.7%]). Mean duration of surgery was 148.2 ± 28.9 minutes. Relief of low back pain and leg pain was significant and stable in the postoperative period as assessed by visual analog scale (P < 0.001). Of patients, 86.9% reported fair, good, or excellent outcomes in terms of pain relief based on MacNab score 2 years after surgery. Patients' level of function in activities of daily living improved significantly based on Oswestry Disability Index score: from 66.8 ± 9.8 before surgery to 33.9 ± 16.5 2 years after surgery (P < 0.001). X-rays and computed tomography at 12 months showed interbody fusion in 46 cases (73.4%), inconclusive results in 13 cases (20.3%), and no fusion in 4 cases (6.3%). No damage to neural or vascular structures and no failure of hardware or screw loosening were recorded.

CONCLUSIONS

MIDLF is a safe, efficient method for surgical treatment of lumbar spine instability. Its limited invasiveness contributes to better preservation of paravertebral muscles and enhanced postoperative spinal stability.

Alternatives to Traditional Pedicle Screws for Posterior Fixation of the Degenerative Lumbar Spine

BACKGROUND

Traditional pedicle screws are currently the gold standard to achieve stable 3-column fixation of the degenerative lumbar spine. However, there are cases in which pedicle screw fixation may not be ideal. Due to their starting point lateral to the pars interarticularis, pedicle screws require a relatively wide dissection along with a medialized trajectory directed toward the centrally located neural elements and prevertebral vasculature. In addition, low bone mineral density remains a major risk factor for pedicle screw loosening, pullout, and pseudarthrosis. The purpose of this article is to review the indications, advantages, disadvantages, and complications associated with posterior fixation techniques of the degenerative lumbar spine beyond the traditional pedicle screws.

METHODS

Comprehensive literature searches of the PubMed, Scopus, and Web of Science databases were performed for 5 methods of posterior spinal fixation, including (1) cortical bone trajectory (CBT) screws, (2) transfacet screws, (3) translaminar screws, (4) spinous process plates, and (5) fusion mass screws and hooks. Articles that had been published between January 1, 1990, and January 1, 2020, were considered. Non-English-language articles and studies involving fixation of the cervical or thoracic spine were excluded from our review.

RESULTS

After reviewing over 1,700 articles pertaining to CBT and non-pedicular fixation techniques, a total of 284 articles met our inclusion criteria. CBT and transfacet screws require less-extensive exposure and paraspinal muscle dissection compared with traditional pedicle screws and may therefore reduce blood loss, postoperative pain, and length of hospital stay. In addition, several methods of non-pedicular fixation such as translaminar and fusion mass screws have trajectories that are directed away from or posterior to the spinal canal, potentially decreasing the risk of neurologic injury. CBT, transfacet, and fusion mass screws can also be used as salvage techniques when traditional pedicle screw constructs fail.

CONCLUSIONS

CBT and non-pedicular fixation may be preferred in certain lumbar degenerative cases, particularly among patients with osteoporosis. Limitations of non-pedicular techniques include their reliance on intact posterior elements and the lack of 3-column fixation of the spine. As a result, transfacet and translaminar screws are infrequently used as the primary method of fixation. CBT, transfacet, and translaminar screws are effective in augmenting interbody fixation and have been shown to significantly improve fusion rates and clinical outcomes compared with stand-alone anterior lumbar interbody fusion.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A Minimally Invasive Technique Using Cortical Bone Trajectory Screws Assisted by 3D-Printed Navigation Templates in Lumbar Adjacent Segment Degeneration

Purpose

Revision surgery for adjacent segment degeneration (ASD) commonly requires exposing and removing the original fixation. To minimize trauma and to reduce the operation time and blood loss, we introduced a minimally invasive lumbar revision technique using cortical bone trajectory (CBT) screws assisted by three-dimensional (3D)-printed navigation templates.

Methods

From April 2017 to October 2019, 18 patients with ASD underwent revision surgery with CBT screws assisted by 3D-printed templates in our hospital. All surgical data, including the operation time, blood loss, and incision length, were recorded. We evaluated the clinical efficacy using the visual analog scale (VAS), the Oswestry Disability Index (ODI), and the Japanese Orthopedic Association (JOA) score. X-ray and computed tomography (CT) scans were used to evaluate the stability of CBT screw fixation, the accuracy of screws, and the fusion rate.

Results

The mean follow-up was 22.4±4.7 months (12–31 months). The VAS, ODI, and JOA scores were analyzed by SPSS 21.0 and showed significant improvement at 2 weeks and the last follow-up compared with preoperative data (P<0.05). Seventy-six CBT screws were inserted with navigation templates; 2 screws were Grade B, and the other screws were Grade 0 or A. Changes in intervertebral height showed good stability of CBT screw fixation (P>0.05). All the patients exhibited satisfactory fusion results.

Conclusion

Revision surgery for ASD with CBT screws assisted by 3D-printed navigation templates has satisfactory clinical efficacy with the advantages of a short operation time, a small incision, and less blood loss.

Pedicle screws versus cortical screws in posterior lumbar interbody fusion surgery for degenerative spondylolisthesis: a systematic review and meta-analysis

BACKGROUND CONTEXT

A few meta-analyses have compared conventional pedicle screws (PS) with cortical bone trajectory-pedicle screws (cortical screw [CS]) in posterior lumbar fusion surgery. However, these studies did not control for diagnosis, which has been shown to impact surgical outcomes.

PURPOSE

To compare PS with CS as a posterior fixation technique in posterior lumbar interbody fusion (PLIF) for degenerative spondylolisthesis (DS).

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

We searched the Cochrane, Embase, and Medline databases for articles that compared postoperative outcomes between PS and CS for posterior stabilization in PLIF for DS with November 11, 2020, as the publication cutoff. The differences in primary and secondary outcome measures were calculated and analyzed for significance (p<.05). All the reported means were pooled.

RESULTS

A total of 916 publications were assessed; 5 studies met all the study criteria. The fusion rates between PS and CS groups were not significantly different (p=.41). Blood loss and operative time were significantly less in the CS group than the PS group (p=.04 and 0.02, respectively), but the length of stay was not significantly different (p=.08). The total complication rate was significantly less in CS group than that in PS group (p=.002). The rates of adjacent segment pathology (ASP) and operation for ASP in the CS group were significantly less than the PS group (p=.03 and .04, respectively).

CONCLUSIONS

Though CS and PS appear to have similar 1-year fusion rates and length of stay, there appears to lower blood loss and operative time with CS. Though encouraging, these findings were based on low-quality evidence from a small number of retrospective studies that are prone to bias.

A method of 3D-3D multi-stage non-rigid registration of the spine based on binocular structured light

BACKGROUND

Intraoperative deformation and radiation are common problems in spinal surgery. A three-dimensional multi-stage dynamic iterative non-rigid registration method of the spine based on binocular structured light is proposed in this paper to overcome these problems.

METHOD

The problem of intraoperative radiation in traditional X-ray and CT is overcome by using binocular structured light. A three-dimensional spinal mask based on binary code is designed to reduce the influence of non-interested regions on the operation. Principal component analysis (PCA) algorithm is used to complete the rough registration between the preoperative CT model of the spine and the reconstructed surface of the intraoperative structured light. A new framework of multi-stage dynamic iterative non-rigid registration of the spine is proposed. The Iterative Closest Point (ICP) algorithm based on bidirectional selection is proposed to complete the single-stage registration of the spine. Then the multi-stage dynamic iterative registration of the spine is completed to solve the problem of large registration error caused by the deformation of the spine.

RESULTS

The method proposed in this paper is compared with traditional registration methods, and its application is verified experimentally. The results show that the registration accuracy and time of the proposed method are 0 . 51 ± 0 . 31  mm and 5 . 21 ± 0 . 23  s, respectively. The accuracy of the method is 81.5% and 78.2% higher than that of the contour method and the method of marker points, respectively.

CONCLUSIONS

The method can effectively avoid intraoperative radiation, reduce the registration error caused by the deformation of the spine, and has a high practicability.

Cortical Trajectory Screw Fixation in Lumbar Spine Surgery: A Review of the Existing Literature

Posterior lumbar fusion is a safe and effective surgical method for diseases, such as lumbar stenosis, spondylolisthesis, lumbar instability, spinal deformity, and tumor. Pedicle screw (PS) fixation was first introduced by Bouche and has been adopted as the gold standard for posterior lumbar fusion. Santoni and colleagues introduced a new methodological screw insertion technique that uses a cortical bone trajectory (CBT), described as that from a medial to lateral path in the transverse axial plane and caudal to the cephalad path in the sagittal plane through the pedicle for maximum contact of the screw with the cortical bone. Owing to the lower invasiveness, superior cortical bone contact, and reduced neurovascular injury incidence, the CBT technique has been widely used in posterior lumbar fusion; however, these advantages have not been proven in clinical/radiological and biomechanical studies. We designed the present study to review the existing evidence and evaluate the merit of CBT screw fixation. Six electronic databases were searched for relevant articles published in August 2020 using the search terms "cortical bone trajectory," "CBT spine," "CBT fixation," "cortical pedicle screws," and "cortical screws." Studies were analyzed and divided into the following groups: "biomechanics investigation," "surgical technique," and "clinical/radiological studies." Most studies compared CBT and PS fixation, and the CBT screw fixation method showed better or similar outcomes.

Risk of pedicle and spinous process violation during cortical bone trajectory screw placement in the lumbar spine

Background

Previous studies have confirmed the feasibility of the cortical bone trajectory (CBT) technique. However, there are few reports on spinous process violation and screw penetration during the screw insertion. The purpose of this study was to evaluate the incidence of spinous process violation and screw penetration through the pedicle during CBT screw insertion.

Methods

Computed tomography (CT) scans with normal lumbar structures were consecutively obtained and three-dimensional (3D) reconstructions of the lumbar spine were created. Bilateral CBT screw placement was simulated on each segment using a screw diameter of 4.5 mm, 5.0 mm, or 5.5 mm. Incidences of these complications were recorded and analyzed.

Results

A total of 90 patients were enrolled. Spinous process violation was observed in 68.3, 53.3, 25.5, 1.7, and 0% from L1 to L5, respectively, using 4.5 mm screws. A significant difference was found among the five segments but this was unconnected to gender or screw diameter. The incidence of screw penetration through the inner wall decreased from L1 to L4; in turn, L1 (16.7–35.5%), L2 (12.7–34.4%), L3 (2.8–23.8%) and L4 (1.1–6.7%). This trend was reversed in L5 (6.7–16.7%). Moreover, screw penetration through the outer wall was rare. The incidence of screw penetration varied with screw size as well as lumbar level, but not with gender.

Conclusions

There are more difficulties of CBT screw fixation in upper lumbar spine. The low rate of screw penetration, using 4.5 mm screws, suggests the safety for CBT fixation in the lumbar spine. Larger screws (5.0 mm or 5.5 mm) are more recommended for use in the lower lumbar spine. Moreover, CBT fixation in L5 deserves greater attention because of the unique morphology of the pedicle.

Comparison of Different Insertion Techniques for Lumbosacral Fixation Improvement: A Finite Element Study

OBJECTIVE

We create a new S1 cortical screw trajectory technique using 3D reconstruction and the finite element (FE) method to provide a more reliable theoretical basis for clinical practices and to advance internal fixation technology for treatment of lumbosacral degenerative diseases.

METHODS

This retrospective study included patients (aged from 40 to 70 years) who needed intervertebral fusion surgery between August 2016 and August 2017. Data of patients with lumbosacral lesions was scanned and measured by 64-row spiral CT, and were then transmitted to the GE-AW4.3 post-processing system for 3D reconstruction. The trajectories of the three different screws were simulated by FE software and processed by mimics software to simulate the screw path: traditional PS fixation (Model A); traditional cortical screw (Model B); and new cortical screw (Model C). The CT value of the bone around the screw canal was recorded. Biomechanical effects of the three screws were analyzed and compared.

RESULTS

The displacement of flexion and extension, the vertebral body stress of right torsion, and the cage stress of flexion showed no significant differences among the three models (P > 0.05). The results demonstrated that cortical screws exceeded pedicle screws in stability and pullout force. Models B and C showed higher vertebral displacement in left bending (0.41 and 0.31 mm) and right bending (0.58 and 0.40 mm), lower vertebral body stress on extension (48.37 and 38.92 MPa), left bending (0.76 and 0.74 mm) and right bending (0.50 and 0.53 mm), and higher cage stress on left bending (162.19 and 160.63 MPa), right bending (150.02 and 150.05 MPa), left torsion (158.45 and 146.27 MPa) and right torsion (167.33 and 171.15 MPa) (all P < 0.05) compared to model A. Compared to Model B, Model C had higher displacement of left and right torsion, lower pressure in extension and flexion, and lower stress on cages in extension (P < 0.05).

CONCLUSION

The new cortical screw insertion method has similar effects to traditional cortical screw fixation. However, it demonstrated advantages in promoting lumbosacral interbody fusion, which protects vessels and nerves.