Cortical Bone Trajectory Pedicle Screw Research Articles

The Fusion Rate of Cortical Bone Trajectory Screw Fixation and Pedicle Screw Fixations in L4‐5 Interbody Fusion: A Retrospective Cohort Study

Although cortical bone trajectory (CBT) screw fixation has been used for several years, the number of studies on its fusion effects is limited. Furthermore, several studies report conflicting outcomes. We aimed to compare the fusion rates and clinical efficacy of CBT screw fixation and pedicle screw (PS) fixation for L4-L5 interbody fusion. This study was a retrospective cohort control study. Patients with lumbar degenerative disease who underwent L4-L5 oblique lumbar interbody fusion (OLIF) or posterior decompression using CBT screws between February 2016 and February 2019 were included. Patients in whom PS was used were matched for age, sex, height, weight, and BMI. Record the operation time, blood loss. All enrolled patients underwent lumbar CT imaging at one-year follow-up to evaluate the fusion rate. At the two-year follow-up the visual analogue scale (VAS), Oswestry disability index (ODI), and Japanese Orthopaedic Association scores (JOA) were used to identify symptom improvement. Independent t-test was used for the comparison, and score data were analyzed using the χ2 and exact probability tests. A total of 144 patients with were included. All patients were followed-up postoperatively for 25-36months (average 32.42 ± 10.55months). Twenty-eight patients underwent OLIF and CBT screw fixation, 36 underwent OLIF and PS fixation, 32 underwent posterior decompression and CBT screw fixation, and 48 underwent posterior decompression and PS fixation. The fusion rates following CBT screw and PS fixations in OLIF were 92.86% (26/28) and 91.67% (33/36), respectively (P=1). The fusion rates following CBT screw and PS fixations in posterior decompression were 93.75% (30/32) and 93.75% (45/48), respectively (P > 0.05). Regardless of OLIF or posterior decompression, there were no significant differences in the VAS, ODI, and JOA scores between patients treated with CBT and PS (P > 0.05). CBT screw fixation can achieve a satisfactory interbody fusion rate with a clinical efficacy similar to that of PS in patients with lumbar degenerative disease, regardless of whether OLIF or posterior decompression was performed.

The treatment efficacy of cortical bone trajectory (CBT) pedicle screws for lumbar degenerative disease in the Chinese Han population

To provide reference data on CBT pedicle screws from CT measurements of L1 to L5 in the Chinese Han population and to assess the treatment efficacy of CBT pedicle screws in cases of lumbar degenerative disease. In total, 100 patients were identified from the CT database for CBT morphometric measurement of the lumbar spine. According to sex and age, patients were divided into four groups. The diameter, length, and angle of the vertebral pedicle and trajectory were measured. Then, a total of 36 patients with lumbar degenerative disease were included in this study for clinical and radiographic evaluation. Demographic characteristics, health-related quality of life (HRQOL), and extent of intervertebral disc herniation and spondylolisthesis were evaluated. The mean diameter and the mean length varied from L1 to L5 in Groups I to IV. The lateral angles ranging from L1 to L5 were 8.9 to 9.2°, 8.7 to 12.2°, 8.7 to 11.2°, and 9.2 to 10.1° in Groups I to IV, respectively. The cephalad angles from L1 to L5 were 23.5 to 28.6°, 24.7 to 26.6°, 25.0 to 28.2°, and 24.7 to 27.9° in Groups I to IV, respectively. In the case series, all patients' neurological function and HRQOL were significantly improved at the final follow-up (p < 0.0001), and 75% of patients achieved satisfaction. The morphology of the lumbar vertebral pedicle varied from L1 to L5, and the trajectory was feasible and safe. CBT pedicle screws were effective in treating lumbar degenerative diseases and benefited the patients.

Comparison of Affected-Vertebra Fixation of Cortical Bone Trajectory Screw and Pedicle Screw for Lumbar Tuberculosis: A Minimum 3-Year Follow-Up.

Purpose This study is aimed at comparing the clinical efficacy of cortical bone trajectory (CBT) screw fixation and pedicle screw (PS) fixation of the affected vertebrae in lumbar tuberculosis. Methods We retrospectively analyzed the outcomes in 52 patients (27 cases in the CBT group, 25 cases in the PS group) with lumbar TB who underwent posterior affected-vertebra fixation combined with anterior debridement and bone grafting. The intraoperative blood loss, operative time, visual analog scale (VAS) scores for incision pain and leg pain, Japanese Orthopedic Association (JOA) score, bone grafting fusion, and complications were recorded. Results All patients were followed up for 35-52 months and achieved good clinical outcomes. There were no differences between the two groups in the operative time, intraoperative blood loss, JOA score, bone grafting fusion, and complications. However, there was a significant difference between the two groups in VAS scores for incision pain on the 1st day and 3rd day after surgery. At the last follow-up, JOA scores were significantly improved in both groups compared to the preoperation. Conclusion This retrospective study confirmed that both the affected-vertebra CBT screw fixation and PS fixation for lumbar TB via posterior and anterior approaches could achieve satisfactory outcomes, while the former resulted in better improvement for postoperative VAS scores.

Can the cortical bone trajectory screw technique be an alternative method to the pedicle screw in posterior lumbar fusion? A systematic review and metaanalysis.

The aim of this study was to verify the practicability of the cortical bone trajectory (CBT) method by comparing the clinical outcomes including the complications between the CBT method and pedicle screws (PSs). MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), web of Science, and SCOPUS electronic databases were searched for relevant articles published through March 2021 that compared the outcomes of the CBT and PSs. The data search, extraction, analysis, and quality assessment were performed according to the Cochrane Collaboration guidelines. The clinical and radiological outcomes of both techniques were evaluated using various outcome measures. Sixteen studies with a total of 1173 patients were included in the study. The outcomes in the meta-analysis indicated that the use of CBT fixation showed better results for overall complications (P < 0.0001), symptomatic adjacent segment disease (sASD) (P = 0.007), superior facet joint violation (SFJV) rate (P = 0.007), operating time (P = 0.007), intraoperative blood loss (P < 0.00001), incision length (P = 0.002), length of hospital stay (P = 0.0006), and revision rates (P = 0.02). However, there were no statistically significant differences in fusion rates or detailed complications including hardware complications, wound infections (all P > 0.05) between the CBT method and PS fixation groups. The present study revealed that the CBT method was associated with higher functional recovery, lower surgical morbidity rates, lower revision rates, and lower overall complication rates including sASD and SFJV rates. However, both the CBT method and PSs had similar fusion rates, complications including hardware complications (screw malposition, screw loosening, and screw pullout) and wound infections. Thus, the CBT method did not outperform the PSs in all aspects. Therefore, it is recommended to select a surgical method in consideration of the patient's bone mineral density, the condition of the pars interarticularis, or the skill level of the surgeon. Prognostic evaluation through long-term follow-up is required, and more high-quality randomized controlled trials are required to verify and strengthen our results. Level III, Therapeutic Study.

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

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. 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. 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). 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.

Comparison of Surgical Outcomes between Cortical Bone Trajectory and Conventional Pedicle Screw Trajectory for Lumbar Degenerative Spondylolisthesis (systematic review of literature)

Abstract Background Pedicle screw fixation the gold standard for lumbar spine stabilization. Pedicle screw has fixation offers multiple advantages, allowing superior correction of spinal deformities, and reduced rates of loss of non-union. Cortical Bone Trajectory (CBT) is a new technique in which screws follow a caudal-to-cephalad path in the sagittal plane and a medial-to-lateral directed path in the transverse plane. CBT is reducing operative and post-operative complications and has high fixation strength. Purpose To Compare the clinical outcomes between CBT and traditional trajectory (TT) in surgical management of degenerative spondylolisthesis. Materials and Methods A comprehensive electronic search in Pubmed, MEDLINE and Chocrane library databases, Google scholar and Research gate for articles that published between 2009 to 2020 using these keywords: Cortical bone trajectory, Cortical bone trajectory-pedicle screw, Pedicle screw. Results The majority of literature suggests that the CBT technique results in similar or decreased postoperative back and leg pain compared to TT. Regarding the disability ODI and the operative time showed no significant differences between the CBT and TT. Radiographic outcomes between both studies show no statistical difference in fusion rates and vertebral slippage. Intraoperative blood loss was significantly less with CBT compared to TT. Conclusion there is no widely accepted consensus regarding comparison of clinical outcomes and complications between the CBT and TT procedures. Generally, indications for CBT and TT are similar between most studies, especially for common pathologies resulting in spondylolisthesis.

Fluoroscopic versus CT-guided cortical bone trajectory pedicle screw fixation: Comparing trajectory related complications

Cortical bone trajectory (CBT) pedicle screw fixation is an emerging technique for treatment of degenerative spine disease which requires either intraoperative fluoroscopy or intraoperative CT guidance (iCT). To date, there has been no direct comparison of these two navigation modalities; here we compare fluoroscopic versus iCT navigation for CBT pedicle screw fixation. We retrospectively reviewed all patients who underwent CBT screw fixation with either fluoroscopic or iCT guidance for lumbar degenerative disease by the senior author. Trajectory-related complications such as medial or lateral breach were compared on postoperative CT, in addition to the incidence of trajectory-related dural tear. We also compared general surgical complications such as postoperative infection and decompression related durotomies. Thirty-eight patients (19 fluoroscopic, 19 CT-guided) who underwent placement of 182 cortical screws (88 fluoroscopic, 94 CT-guided) were identified. In terms of trajectory-related complications, the iCT cohort had fewer medial breaches (1/94) compared to the fluoroscopic cohort (6/88) (p = 0.05). Each group had one lateral breach (p = 0.73). There was one case of CSF leak from screw placement in the fluoroscopic cohort, but none in the iCT cohort (p = 0.48). Overall, there were eight trajectory-related complications in the fluoroscopic cohort versus two in the iCT cohort (p = 0.04). Our data suggests statistically significant decreased trajectory-related complications with iCT-guided CBT screw fixation as compared to fluoroscopically guided. In terms of general surgical complications, while we observed increased postoperative infections in our fluoroscopic cohort, there was no statistically significant difference.

Case-control study on cortical bone trajectory screw and pedicle screw internal fixation for the treatment of senile patients with lumbar tuberculosis

To compare clinical effect of cortical bone trajectory (CBT) screw and pedicle screw (PS) internal fixation in treating senile patients with lumbar tuberculosis. From January 2014 to January 2017, 42 senile patients with lumbar tuberculosis were divided into CBT group and PS group, 21 patients in each group. In CBT group, there were 12 males and 9 females, aged from 64 to 81 years old with an average of (72.52±9.25) years old, T value of bone mineral density was (-2.69±0.17) g / cm3, posterior CBT screw internal fixation and anterior debridement, interbody fusion with bone grafting was performed. In PS group, there were 11 males and 10 females, aged from 63 to 85 years old with an average of (71.42±9.81) years old, T value of bone mineral density was (-2.70±0.21) g / cm3, PS internal fixation and anterior debridement, interbody fusion with bone grafting were performed. Length of posterior incision, intraoperative bleeding volume, operation time, time of bone graft fusion and complications between two groups were compared. Level of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), segment kyphotic Cobb angle before and after operation were compared, VAS score was used to evaluate pain releasing, JOA score was applied to evaluate clinical effect. All patients were followed up from 12 to 21 months with an average of (15.00±3.57) months. No reoccurrence of lumbar tuberculosis and screw loosing occurred. There were statistical difference in length of incision, intraoperative bleeding volume, operation time between two groups (P<0.05). Level ofESR and CRP between two groups at 2 weeks, 1 month and 6 months after operation were improved after operation, while there were no differences between two groups (P>0.05). There were no statistical differences in complications, time of bone graft fusion and segment kyphotic Cobb angle at 1 week after operation between two groups (P>0.05). There was difference in Cobb angle at 12 months after operation (P<0.05). For VAS score, there were no difference between two groups before operation and 3 months after operation(P>0.05), but VAS score at 3 months after operation were improved after operation between two groups (P<0.05).For JOA score, there were no difference between two groups before operation, 3 and 12 months after operation, and JOA score at 3 and 12 months after operation were improved than that of before operation between two groups (P<0.05). Both of CBT screw internal fixation and PS screw internal fixation could achieve satisfying results for the treatment of elderly patients with lumbar tuberculosis. PSinternal fixation has a long fixation but great trauma. However, CBT screw internal fixation only needs to fix adjacent segments of the lesion to reduce the fixation range, which has advantages of less trauma and strong screw holding force.

Comparison of cortical bone trajectory versus pedicle screw techniques in lumbar fusion surgery: A meta-analysis.

Background:Biomechanical studies have demonstrated that cortical bone trajectory (CBT) screw can provide a 30% increase in uniaxial yield pullout load than pedicle screw (PS). In addition, the insertion torque of CBT screw is 1.71 times higher than that of PS. A meta-analysis was conducted to evaluate clinical results between CBT screw technique and PS technique in lumbar fusion surgery.Methods:An extensive search of literature was performed in PubMed, Embase, the Cochrane library. The following outcomes were extracted: visual analog scale (VAS), Oswestry disabilities index (ODI), Japanese Orthopaedic Association (JOA) score, complications, fusion rates, hospital stay, incision length, blood loss, and operation time. Data analysis was conducted with RevMan 5.3 and STATA 12.0.Results:A total of 12 studies were included in the final analysis. The results indicated that CBT group with less blood loss [P < .01], less hospital stay [P < .01], and less incision length [P < .01] than PS group. There were no significant differences between 2 groups in other clinical parameters and outcomes.Conclusion:CBT technique provided similar clinical outcomes and fusion rates compared to PS technique in lumbar fusion surgery. However, CBT technique provided additional benefits of less blood loss, less hospital stay, and less incision length.

Retrospective Analysis of EMG-evoked Potentials in Cortical Bone Trajectory Pedicle Screws.

This is a retrospective analysis of electromyographic (EMG) stimulation thresholds of 64 cortical bone trajectory (CBT) screws. The authors seek to determine whether recordings below stimulation threshold correlate with CBT screw pedicle breach on computed tomographic imaging, and to explore which specific nerve roots are most at risk with this new trajectory. Intraoperative EMG monitoring has been utilized to verify accurate placement of pedicle screws. Although CBT screws are becoming increasingly popular, to the authors' knowledge there are no existing evaluations of the accuracy of intraoperative triggered EMG (tEMG) monitoring in this trajectory. Retrospective analysis of EMG stimulation thresholds of 64 CBT screws placed in patients at NYU Langone Medical Center from 2015-2017. EMG results including threshold values and muscle group stimulated were correlated with screw positioning determined on postoperative or intraoperative computed tomographic imaging. In total, 4.7% of EMG threshold values indicated true breach, 1.6% were falsely positive for breach, 76.5% showed true absence of breach, 17.1% failed to reveal a present breach though 0% of medial breaches were undetected. L4 screws showed tEMG responses from adductor longus in 22%, L5 screws, from rectus femoris in 16.7%, and S1 screws from tibialis anterior in 50%. tEMG testing is effective for medial breaches in CBT screws. In addition, there is evidence that bicortical placement of these screws causes lower stimulation values due to distal breach. Importantly, it seems that this is due in part to stimulation of the exiting nerve root at the level above.

Cortical Trajectory Pedicle Screws for the Fixation of Traumatic Thoracolumbar Fractures.

ObjectiveCortical bone trajectory pedicle screws (CBT) have a different trajectory compared to traditional pedicle screws (PS) and they may confer biomechanical advantages in some patient populations. We hypothesize that the placement of CBT in traumatic thoracolumbar fractures could be an alternative technique to the traditional utilization of PS.MethodsSingle surgeon, retrospective study was performed at a Level 1 Trauma Center from 2013 to 2017. All patients aged between 18 and 90 years with operative AO classification A, B, and C traumatic thoracolumbar fractures were included. Patients with pathological fractures, active spinal infections, or history of vertebral augmentation were excluded. Age, injury severity score (ISS), AO classification, operative time, estimated blood loss (EBL), length of stay (LOS), and presence of proximal junctional kyphosis (PJK) or construct failure were compared between CBT and PS groups. The PS group was further separated into open reduction internal fixation (ORIF) and minimally invasive spine (MIS) groups. All CBT and ORIF cases were completed via open incisions allowing arthrodesis of the involved lamina and facet joints whereas no arthrodesis was completed in the MIS patients. Choice of technique was at the attending surgeon’s discretion.ResultsThe study included 71 patients, out of which 12 received CBT and 59 received PS. Of the 59 PS patients, 39 were ORIF and 20 were MIS. The average operative time was 22.9 minutes less in CBT compared to ORIF (p = 0.24). EBL was 337.50 mL for CBT, 184.33 mL for MIS, and 503.33 mL for ORIF (p = 0.01) demonstrating that MIS technique results in a significantly reduced blood loss. However, EBL was comparable for CBT versus MIS (p > 0.05). ISS was not significantly different between the three groups (p = 0.89). LOS was 4.06 days fewer for CBT patients compared to ORIF patients (p = 0.36). There was one case of construct failure as well as one case of incisional site infection in the PS group, but none were found in the CBT group. Instances of PJK complications were determined by the change in the Cobb angle over time and they were not statistically different between the three groups (p = 0.68).ConclusionsCBT is noninferior to PS in the fixation of unstable adult traumatic thoracolumbar fractures. With the exception of EBL, CBT was not statistically different compared to MIS and ORIF. This study establishes a precedent to expand the application of this new technique and investigate with larger sample sizes.

Comparative Study of Two Surgical Techniques for Proximal Adjacent Segment Pathology after Posterior Lumbar Interbody Fusion with Pedicle Screws: Fusion Extension using Conventional Pedicle Screw vs Cortical Bone Trajectory-Pedicle Screw (Cortical Screw)

To present a minimally invasive surgical technique using cortical bone trajectory pedicle screws (cortical screws [CS]) for adjacent segment pathology (ASP) after lumbar fusion surgery, and to thoroughly compare postoperative outcomes of surgical techniques with either a CS or conventional pedicle screws (PS) for ASP at a 1-year follow-up. Among 59 patients who underwent surgical treatment for proximal ASP after lumbar fusion surgery, 53 patients who met the study criteria (group A, 31 patients with conventional technique using PS; group B, 22 patients with minimally invasive technique using CS) were enrolled in the study. The primary outcome measure was the fusion rate at 1 year after surgery, and secondary outcome measures included patient satisfaction, clinical outcomes, radiologic outcomes, and surgical outcomes and complications. Fusion at 1 year postsurgery was achieved by 90% of the patients in group A with PS and 91% of those in group B with CS (P > 0.99). Patient satisfaction at 1 month postsurgery (P= 0.03) and pain intensity within 1 month postsurgery (P= 0.04) were significantly better in group B compared with group A. Regarding surgical outcomes, blood loss was significantly less, operation time and length of hospital stay were significantly shorter, and the incision was significantly shorter n group B than in group A. Other clinical parameters and outcomes were similar in the 2 groups. We suggest that a minimally invasive surgical technique using CS for ASP can be a viable alternative to a conventional surgical technique using PS.

Optimized Screw Trajectory for Lumbar Cortical Bone Trajectory Pedicle Screws Based on Clinical Outcome: Evidence Favoring the Buttress Effect Theory.

Cortical bone trajectory (CBT) is a relatively new technique for pedicle screw insertion in the field of spine surgery. Previous studies have demonstrated the significantly better pullout and toggle characteristics the new method offers, and it appears to have certain advantages over the widely used traditional trajectory. The mechanism of the pullout and toggle characteristics still remains unknown. To report the medium- to long-term follow-up findings of patients who underwent posterior lumbar interbody fusion or posterior lumbar fusion (PLIF/PLF) at our institution and to discuss the ideal screw trajectory when using this technique. Retrospective radiologic study. Fifty-five patients who underwent PLIF/PLF for lumbar spondylosis using the new technique between January 2011 and January 2016 were included. Clinical outcome was assessed using the Japanese Orthopaedic Association scores for low back pain and visual analog scale scores. Screw loosening was evaluated via the presence of a translucent zone surrounding the pedicle screw using plain X-radiography (Xp). The screw trajectory was evaluated by measuring the rostral range (RR) and the lateral range score (LRS). The RR is the angle between the line drawn along the distal end plate of the vertebra and the line drawn along the screw on the lateral view. The LRS is the score given depending on the position of the tip of the screw seen on the Xp taken in the anteroposterior (AP) view. The pedicle ring is equally divided into the medial third (zone A), central third (zone B), and the lateral third (zone C) by four vertical lines. A score of 0 to 3 points is given depending on the position of the tip of the screw: 0, outside the pedicle ring; 1, zone A; 2, zone B; and 3, zone C. Bone fusion was recorded in 49 patients (49/55 patients). The total number of screws with a visible translucent zone on Xp was 26 (26/242 screws). When the screws are inserted at a more acute angle in the lateral view (low RR) or when the screws are directed more medially (low LRS), the risk of developing a translucent zone around the pedicle screw increased. With CBT, the pedicle screws are inserted from the pars interarticularis that is rich in cortical bone, strong enough to withstand the substantial forces usually encountered in the region. Our clinical data suggest that the optimal screw trajectory is one where the screw is inserted at an angle > 22.55 degrees (high RR) on the lateral view Xp and where the tip of the screw is directed toward the lateral third of the pedicle on the AP Xp. We believe the naturally occurring buttress effect that exists in the vertebra may give CBT a mechanical and anatomical advantage over the traditional screw trajectory.

Morphometric Measurement of the Lumbosacral Spine for Minimally-Invasive Cortical Bone Trajectory Implant Using Computed-Tomography

Introduction The cortical bone trajectory (CBT) is a novel lumbar pedicle screw trajectory. There is a dearth of literature on CBT screw insertion techniques. The aim of this study was to conduct a detailed morphometric measurement of the lumbosacral spine for CBT pedicle screw starting point, trajectory, length and diameter, using the inferior facet of the cephalad level as a bony landmark. Methods The 3-dimensional reconstruction computed tomography (CT) scans of 86 adults who underwent examination of the lumbosacral spine were studied. The junction of the inferior and medial border of the smallest coronal section of the lumbar pedicle was traced in lumbar segments while the junction of the medial border of the sacral 1 (S1) pedicle and the inferior border of the L5 inferior facet was traced in S1 segments. The starting point was defined to be the projective point on the vertebral plate by this junction. The distances from the starting point to the inferior, lateral and medial border of the inferior facet of the cephalad level, and the inferior border of the transverse process were measured. The trajectory of pedicle screws for the lumbar and S1 segments was determined in the axial and sagittal planes. The angle formed between this trajectory and a line from the vertebral midline was defined as the transverse angle (TA). The angle formed between this trajectory and a line from superior margin of the vertebral body was defined as the cephalad angle 1 (CA1). Cephalad angle 2 (CA2) was defined as the angle formed between the same trajectory on the sagittal plane and a line from the posterior margin of the pars interarticularis. The maximum pedicle screw diameter, as well as the maximum pedicle screw length of the lumbosacral segments was measured on axial and sagittal CT scans, respectively. Results The distances from the inferior border of inferior facet to the starting point from L1 to S1 were 8.9, 6.3, 4.1, 2.9, 1.4 and 0 mm, respectively. The distances from the medial border of the inferior facet to the starting point from L1 to S1 were between 3 to 4mm. The percentages of the distance from the starting point to the medial border of the inferior facet from L1 to S1 were 80.5, 70.1, 61.6, 48.6, 40.8 and 29.3%, respectively. TA from L1 to S1 were 9.0, 9.6, 11.3, 13.5, 15.5, and 8.2 degrees, respectively. CA1/CA2 from L1 to S1 were 26.7/38.7, 26.0/38.7, 26.9/38.0, 24.4/37.2, 22.9/35.1 and 18.4/47.8 degrees, respectively. The maximum diameters of the trajectory from L1 to S1 were 4.8, 5.1, 6.1, 6.8, 7.8, and 6.1mm, respectively. Twenty-five mm was a safe border as the maximum length of the pedicle screw from L1 to S1. Conclusions The inferior facet of the cephalad level is an attractive bony landmark for establishing a starting point of CBT for minimally-invasive spine surgery.

Medialized, Muscle-Splitting Approach for Posterior Lumbar Interbody Fusion: Technique and Multicenter Perioperative Results.

Retrospective, multicenter study of perioperative results OBJECTIVE.: The purpose of this study was to describe the surgical technique for medialized posterior lumbar fusion as well as present preliminary complication and treatment results from a multicenter retrospective study. Posterior exposures remain the most commonly performed approaches for spinal fusion. Conventional open posterior exposures, however, have relatively high exposure-related morbidity and postoperative infection rates. Less invasive exposures for transforaminal and anterior (lateral) interbody fusion have been widely used over the past decade, but the need for bilateral posterior exposure has challenged the development of less invasive exposures for direct posterior approaches for lumbar fusion. Consecutive patients treated with minimally invasive spine (MIS) posterior lumbar interbody fusion with medialized cortical bone trajectory pedicle screw and rod fixation were identified from four sites in the United States. Of the 138 patients identified, 61% of patients were treated for degenerative spondylolisthesis at 167 levels, most commonly at L4-5 (62%). Perioperative treatment, complication, and reoperation data were collected to describe early feasibility of the approach. Mean total operative time was 135 minutes with an average of 236 mL of blood loss. Mean total postoperative length of hospital stay was 2.6 days, with 25% of patients discharged on the same day or within 23 hours of surgery. Total perioperative complication rate in 138 patients was 10.1% (14/138) with three related reoperations. Intraoperative complications included five (3.6%) instances of incidental durotomy, without any progression to persistent cerebrospinal fluid leaks. Nine (6.5%) postoperative complications occurred, including one L5 vertebral body fracture, two pulmonary embolisms, one deep vein thrombosis, one urinary tract infection one instance of urinary retention, two superficial surgical site infections, and one patient with persistent pain at 6 months postoperative. Three (2.2%) reoperations were performed, one for revision of the L5 vertebral body fracture, and two for wound debridement. No instances of postoperative radiculitis or neurological injury were observed. Medialized, muscle-sparing posterior exposures with specialized instrumentation can be performed in patients with degenerative lumbar pathology with low surgical morbidity and blood loss and a short length of postoperative hospital stay. 4.

Lumbar Spinal Fixation with Cortical Bone Trajectory Pedicle Screws in 79 Patients with Degenerative Disease: Perioperative Outcomes and Complications

Biomechanical studies demonstrate that cortical bone trajectory pedicle screws (CBTPS) have greater pullout strength than traditional pedicle screws with a lateral-medial trajectory. CBTPS start on the pars and angulate in a mediolateral-caudocranial direction. To our knowledge, no large series exists evaluating the perioperative outcomes and safety of CBTPS. We retrospectively reviewed all patients who received lumbar CBTPS at our institution. Data were collected regarding patient demographics, use of image guidance, operative blood loss, hospital stay, and postoperative complications. A total of 79 patients undergoing CBTPS fusion for degenerative lumbosacral disease with back pain were included in the analysis (42 female, 37 male; October 2011-January 2015). Twenty patients (25.3%) had previous lumbar spine surgery, 39 (49.4%) had a smoking history, and mean body mass index was 28.7. Mean length of stay was 3.5 days, and mean operative blood loss was 306.3 mL. Image guidance was used in 69 (87.3%) cases. A total of 66 (83.5%) fusions were single level, and 54 (68.4%) fusions were single level without previous surgery. There were 9 complications in 7 (8.9%) patients; these included hardware failure, pseudarthrosis, deep vein thrombosis, pulmonary embolism, epidural hematoma, and wound infection. No complications were caused by misplaced screws. Mean follow-up was 13.2 months. As CBTPS becomes increasingly popular among spine surgeons performing lumbar fusion, this report provides an important evaluation of technique safety and acceptable perioperative outcomes.

Morphometric measurement of the lumbosacral spine for minimally invasive cortical bone trajectory implant using computed tomography.

The cortical bone trajectory (CBT) is a novel lumbar pedicle screw trajectory. The aim of this study was to conduct a detailed morphometric measurement of the lumbosacral spine for CBT pedicle screw, using the inferior facet of the cephalad level as a bony landmark. The three-dimensional computed tomography (3D-CT) scans of 86 adults who underwent examination of the lumbosacral spine were studied. The distances from the starting point to the inferior, lateral and medial border of the inferior facet of the cephalad level were measured. The angles formed between the screw trajectory and the sagittal plane, the superior endplate of the vertebral body and the posterior margin of the pars interarticularis were defined as the transverse angle (TA), cephalad angle 1 (CA1) and cephalad angle 2 (CA2), respectively. The distances from the inferior border of inferior facet to the starting point from L1 to S1 were 8.9, 6.3, 4.1, 2.9, 1.4 and 0 mm, respectively. The distances from the medial border of the inferior facet to the starting point from L1 to S1 were between 3 and 4 mm. TA from L1 to S1 was 9.0°, 9.6°, 11.3°, 13.5°, 15.5°, and 8.2°, respectively. CA1/CA2 from L1 to S1 was 26.7°/38.7°, 26.0°/38.7°, 26.9°/38.0°, 24.4°/37.2°, 22.9°/35.1° and 18.4°/47.8°, respectively. The maximum screw diameters from L1 to S1 were 4.8, 5.1, 6.1, 6.8, 7.8, and 6.1 mm, respectively. Twenty-five millimeter can serve as a safe maximum length of CBT pedicle screws. The inferior facet of the cephalad level is an attractive bony landmark for establishing a starting point of CBT for minimally invasive spine surgery.

Maximal access surgery for posterior lumbar interbody fusion with divergent, cortical bone trajectory pedicle screws: a good option to minimize spine access and maximize the field for nerve decompression.

First advocated by Santoni et al. in 2009, the cortical bone trajectory pedicle screw technique is an alternative to the traditional, convergent technique that shows comparable biomechanical features and potentially requires less aggressive tissue retraction. Aim of this therapy note is to describe this new technique focusing on main advantages and limitations. The authors provide a detailed description of the surgically relevant anatomy focusing on the positioning of the cortical trajectory screws. The surgical technique is then described in a precise step-by-step manner, stressing complication avoidance. The maximal access surgery posterior lumbar interbody fusion approach is a safe, reproducible procedure allowing for a traditional lumbar spine approach with the benefits of minimal facet joint manipulation and potentially preserving part of their neural innervation and a large part of the paraspinous musculature. A dedicated self-retaining retractor and directional neuromonitoring may guide surgeons during the procedure. Nevertheless, the surgeon's knowledge of anatomical landmarks, response to visual and tactile cues and intraoperative decision-making skills remain of paramount importance.

Early clinical results with cortically based pedicle screw trajectory for fusion of the degenerative lumbar spine

This study reviews the outcomes and revision rates of degenerative lumbar fusion surgery using cortical trajectory pedicle screws in lieu of traditional pedicle screw instrumentation. Pedicle screw fixation can be a challenge in patients with low bone mineral density. Wide posterior approaches to the lumbar spine exposing lateral to the facet joints and onto transverse processes causes an additional degree of muscular damage and blood loss not present with a simple laminectomy. A cortical bone trajectory pedicle screw has been proposed as an alternative to prevent screw pullout and decrease the morbidity associated with the wide posterior approach to the spine. We present a series of eight consecutive patients using a cortical bone trajectory instead of traditional pedicle screw fixation for degenerative conditions of the lumbar spine. A retrospective review of our institutional registry data identified eight patients who had cortical screws placed with the assistance of O-arm Stealth navigation (Medtronic Sofamor Danek, Memphis, TN, USA) from 2010–2013. We analyzed the need for revision, the maintenance of reduction and the incidence of screw pullout or breakage. Our review demonstrated that two of eight patients were revised at an average of 12months. The reasons for these revisions were pseudarthrosis and caudal adjacent segment failure. All patients who were revised had frank screw loosening. We present early clinical results of a new technique that has been shown to have a better fixation profile in laboratory testing. Our less than favorable early clinical results should be interpreted with caution and highlight important technical issues which should be considered.

A Survey on Cortical Bone Trajectory for Spinal Fusions

There have been a number of developments in screw design and implantation techniques over recent years, including proposal of an alternative trajectory entitled as cortical bone trajectory (CBT). Cortical bone trajectory has been investigated in recent medical treatments as an alternative for screw fixation aimed at increasing purchase of pedicle screws in higher density bone. CBT screw insertion follows a lateral path in the transverse plane and caudocephalad path in the sagittal plane. This technique has been advocated because it is reportedly less invasive, improves screw−bone purchase and reduces neurovascular injury. Furthermore CBT pedicle screw fixation provides stabilization to multilevel lumbar segment with low-grade spondylolisthesis comparable to the standard trajectory pedicle screw construct. However, these claims have not been supported by robust clinical evidence. Recent investigations focus on evaluations of CBT as a pioneer method.