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Robotic navigation is a new and rapidly emerging niche within minimally invasive spine surgery. The robotic arms-race began in 2004 and has resulted in no less than four major robotic surgical adjuncts. Current Food and Drug Administration (FDA)-approved applications of robotic navigation are limited to pedicle screw instrumentation, but new indications and experimental applications are rapidly emerging. As with any new technology, robotic navigation must be vetted for clinical efficacy, efficiency, safety, and cost-effectiveness. Given the rapid advancements made on a yearly basis, it is important to make frequent and objective assessments of the available technology. Thus, the authors seek to provide the most up-to-date review of the history, currently available technology, learning curve, novel applications, and cost effectiveness of today’s available robotic systems as it relates to spine surgery.

In contrast to infection and curve progression, return to OR for implant malposition is potentially within the surgeon’s control. With increasing surgeon familiarity with freehand/fluoroscopic pedicle screw placement, rates of return to OR due to malposition may have decreased over time. We sought to document the incidence and risk factors for return to OR due to screw malposition in a large cohort of patients with idiopathic scoliosis. AIS patients enrolled in a multicenter prospective registry with minimum 2-year follow-up undergoing PSF between 2003 and 2017 were included. Surgeries with the use of intraoperative CT-guided navigation were excluded. Return to OR due to screw malposition over time was tabulated. Lenke class, age at surgery, year of surgery, height, weight, surgeon and site were evaluated. 2435 patients underwent PSF with non-navigated open pedicle screw instrumentation. Mean age was 14.6 years, mean thoracic curve magnitude was 53°, and mean lumbar was 40°. Patients did not routinely undergo intraoperative or postoperative CT evaluation. There were 10 returns to OR for screw malposition at a mean of 0.83 years postoperatively (range 0.1–3.4 years), for an overall incidence of 0.4%. Of the 14 screws, 10 were thoracic, 7 were left-sided. No association was found between screw malposition and curve size, enrolling site, surgeon, BMI, Lenke class, or age. Five patients had radiculopathy which improved after screw revision. Return to OR for screw malposition changed from 2003 to 2017 (1–0.2%) but this did not reach statistical significance. Although the incidence of asymptomatic malpositioned screws is unknown, the rate of return to the OR for implant malposition overall in this registry was 1 in 250 patients. Recent data suggest the rate has decreased to 1 in 500 patients. Further work may determine whether enabling technologies can reduce the rate, ideally to a “never event”.

Background K-wireless robotic pedicle screw instrumentation with navigation is a new technology with large potential. Barriers to adoption are added registration time with robotic-navigated system and reliable screw positioning. Understanding the learning curve and limitations is crucial for successful implementation. The purpose of this study was to describe a learning curve of k-wireless robotic assisted pedicle screw placement with navigation and compare to conventional techniques. Methods A retrospective review of prospectively collected data of 65 consecutive adult patients underwent robotic-navigated posterior spinal fusion by a single spine surgeon. Registration, screw placement, and positioning times were recorded. All patients underwent intra-operative 3D fluoroscopy and screw trajectory was compared to pre-operative CT. Results A total of 364 instrumented pedicles were planned robotically, 311 (85.4%) were placed robotically; 17 screws (4.7%) converted to k-wire, 21 (5.8%) converted to freehand, and 15 (4.1%) planned freehand. Of the 311 robotically placed pedicle screws, three dimensional fluoroscopic imaging showed 291 (93.5%) to be GRS Grade A in the axial plane (fully contained within the pedicle) and 281 (90.4%) were GRS Grade A in the sagittal plane. All breached screw deviations from plan were identified on 3D fluoroscopy during surgery and repositioned and confirmed by additional 3d fluoroscopy scan. Reasons for conversion included morphology of starting point (n=18), soft tissue pressure (n=9), hypoplastic pedicles (n=6), obstructive reference pin placement (n=2), and robotic arm issues (n=1). Seventeen (5.5%) critical breaches (≥2-4 mm) were recorded in 11 patients, 9 (2.9%) critical breaches were due to soft tissue pressure causing skive. Two patients experienced 6 (1.9%) critical breaches from hypoplastic pedicles, and 3 (0.9%) unplanned lateral breaches were found in another patient. One patient (0.3%) experienced skive due to morphology and spinal instability from isthmic spondylolisthesis. Imaging showed 143 screws placed medially to plan (1.2±0.9 mm), 170 lateral (1.2±1.1 mm), 193 screws caudal (1.0±0.6 mm) and 117 cranial (0.6±0.5 mm). No adverse clinical sequelae occurred from implantation of any screw. Conclusions The learning curve showed improvement in screw times for the first several cases. Understanding the learning curve and situations where the robotic technique may be suboptimal can help guide the surgeon safe and effectively for adoption, as well as further refine these technologies.

Study Design: Systematic review and meta-analysis. Objectives: Malposition of pedicle screws during instrumentation in the lumbar spine is associated with complications secondary to spinal cord or nerve root injury. Intraoperative triggered electromyographic monitoring (t-EMG) may be used during instrumentation for early detection of malposition. The association between lumbar pedicle screws stimulated at low EMG thresholds and postoperative neurological deficits, however, remains unknown. The purpose of this study is to assess whether a low threshold t-EMG response to lumbar pedicle screw stimulation can serve as a predictive tool for postoperative neurological deficit. Methods: The present study is a meta-analysis of the literature from PubMed, Web of Science, and Embase identifying prospective/retrospective studies with outcomes of patients who underwent lumbar spinal fusion with t-EMG testing. Results: The total study cohort consisted of 2,236 patients and the total postoperative neurological deficit rate was 3.04%. 10.78% of the patients incurred at least 1 pedicle screw that was stimulated below the respective EMG alarm threshold intraoperatively. The incidence of postoperative neurological deficits in patients with a lumbar pedicle screw stimulated below EMG alarm threshold during placement was 13.28%, while only 1.80% in the patients without. The pooled DOR was 10.14. Sensitivity was 49% while specificity was 88%. Conclusions: Electrically activated lumbar pedicle screws resulting in low t-EMG alarm thresholds are highly specific but weakly sensitive for new postoperative neurological deficits. Patients with new postoperative neurological deficits after lumbar spine surgery were 10 times more likely to have had a lumbar pedicle screw stimulated at a low EMG threshold.

BACKGROUND We report a case of Intracardiac, pulmonary, and intravenous cement embolism after cement-augmented pedicle screw instrumentation in treating spondylolisthesis underlying osteoporotic bone, which was successfully managed by conservative treatment. We describe the treatment and outcome of the patient, hoping to shed light on the management of bone cement embolism. CASE SUMMARY A 67-year-old female suffered from progressive low back pain and numbness in lower extremities for 30 years. She was diagnosed with L4 and L5 spondylolisthesis, spinal stenosis, and osteoporosis. The patient underwent spinal canal decompression, an interbody fusion of L4/5 and L5/S1, cement-augmented pedicle screw instrumentation in L4-L5 segments, and regular pedicle screw in S1 segments. Three days postoperatively, a sudden drop in oxygen saturation occurred. Computerized tomography scan confirmed Intracardiac, pulmonary, and intravenous embolism. The patient was treated conservatively by continuous low-flow oxygen inhalation, anti-coagulation, and antibiotic therapy for 1 mo and continued anticoagulation treatment for 6 mo. The patient showed no further symptoms in a 30-mo follow-up. CONCLUSION Intracardiac, pulmonary cement embolism after cement-augmented pedicle screw instrumentation is extremely rare. Careful clinical and radiographic evaluation is required in multiple sites of bone cement embolism. Conservative treatment may be a primary consideration in scattered emboli without life-threatening conditions, but a clinical decision should be made on an individualized basis.

Background We evaluate the feasibility and potential advantages of spinal CT navigation in the placement of pedicle screws at the cervicothoracic junction in the sitting position to counteract the anatomy-related limitations of 2D fluoroscopy. Methods We retrospectively analyze the data from 15 patients who underwent CT-based navigation-guided placement of a total of 36 pedicle screws at the cervicothoracic junction in the sitting position. Results CT-based spinal navigation is a useful method in increasing accuracy of pedicle screw instrumentation in the sitting position, successfully counteracting the anatomy-related limitations of 2D fluoroscopy at the cervicothoracic junction. Conclusion CT-based navigation-guided placement of pedicle screws at the cervicothoracic junction in the sitting position proved to be an accurate, safe, and user-friendly method.

Introduction: Free-hand technique is one of the techniques used by spine surgeon during pedicle screw instrumentation of surgical correction of spinal deformities, including scoliosis. The previous studies showed that this technique is safe. However, some inherent factors may influence its outcomes, including screw breaching which is potentially violates spinal cord and other intimate structures. To con?rm the safety and accuracy of this technique, additional study measuring the breach rate of pedicle screw placement in scoliosis is mandatory. Materials and Methods: We performed a retrospective study of patients with adolescent idiopathic scoliosis (AIS) from Fatmawati General Hospital, Jakarta, treated for surgical correction during a period of 2017–2018 using free-hand technique for pedicle screw instrumentation. Post-operative computed tomography scan (CT scan) was analyzed to measure the medial and lateral breaches. P < 0.05 was deemed to be statistically significant. Results: A total of 94 pedicle screws from six female patients with AIS were included in our study. Overall breach occurred in 33% instrumented screws, the majority of it was a low-grade breach. Of the breached screws, medial and lateral breach occurred in 20% and 12% of screws, respectively. There were no differences in the overall, medial, and lateral breaches between thoracic and lumbar vertebrae (P > 0.05). Medial breach was significantly higher in middle thoracic segment compared to other thoracic segments (P = 0.048). Risk of medial breach was 3 times higher in the convex side of deformity (P = 0.012), whereas risk of lateral breach was 4.6 times higher in the concave side of the deformity (P = 0.021). Conclusion: The majority of breached screws were low-grade violation within the safe zone, with no neurological sequelae. Our study found that free-hand technique is safe and effective method of pedicle screw instrumentation for correction of AIS. Some inherent factors may influence the risk of

Neuromuscular scoliosis (NMS) is often associated with rapid progressive spinal deformities. Indications, when to extend the instrumentation to the pelvis for pelvic obliquity are not generally accepted at this time. This study reports on the indications, surgical technique and results using pedicle screw instrumentation exclusively with or without pelvic fixation for spine fusion in patients with NMS.Thirty-seven NMS patients were treated with pedicle screw instrumentation (PSI) between 2007 and 2013 with a minimum follow-up of 24 months. The mean age at the time of operation was 14.91 ± 2.03 years (range, 11.17-18.58). Posterior spine fusion (PSF) was conducted in 33 patients; 4 patients underwent a combined anterior spinal release followed by PSF during one-stage surgery. Pelvic fixation was achieved by ilium screws combined with S-1 screws in 4 cases and by sacral-alar-iliac (SAI) technique by Sponseller in 9 cases, respectively.The mean primary Cobb angle was 65.5° (range, 14-103°) and improved significantly to 19.8° (range, 1-50°, p 0.001) after surgery and 20.5° (range, 3-57, p = 0.47) at 2 years FU, respectively. Besides, an improvement of pelvic obliquity and T1 tilt angle could be detected. Major complications occurred in 19% and minor complications in 32%.Pedicle screw fixation only for spine fusion in patients with NMS can be applied safely with reasonable complication rates. An excellent correction in all planes, a significant improvement of the pelvic obliquity and almost no loss of correction at 2 years FU were observed.

Pediatric spine trauma presents unique management challenges. These injuries are often the result of high-energy mechanisms and are associated with other serious injuries that can complicate surgical and nonsurgical approaches. The pediatric population presents a host of challenges related to patient compliance, healing challenges, and patient tolerance of therapy. Percutaneous pedicle screw instrumentation, temporary fixation without fusion, continues to expand in its role of pediatric spine fracture treatment. Compared with open instrumentation and fusion, this technique addresses many of the previously mentioned challenges. Additional study is needed to evaluate the clinical utility of this approach in pediatric spinal fractures.

To investigate whether the rotation of preoperative-presumed lowest instrumented vertebra (LIV) is a risk factor for adding-on (AO) in adolescent idiopathic scoliosis (AIS) treated with selective posterior thoracic fusion (sPTF). A total of 196 AIS patients of Lenke type 1A or 2A with minimum 2-year follow-up after sPTF with all pedicle screw instrumentation were included. Radiographical parameters were measured as follows: preoperative rotation angle of presumed LIV and LIV + 1, LIV + 1/LIV rotation difference, postoperative rotation angle of LIV and LIV derotation angle on CT scans. Patients were classified into AO group and non-AO group during the follow-up. The parameters were compared between the two groups to investigate risk factors for AO. Among 196 patients, 40 (20.4%) patients developed with AO at the final follow-up. Compared with non-AO group, patients with AO had significantly larger preoperative rotation angle of presumed LIV (8.8° ± 3.4° vs. 3.4° ± 2.9°, P

Pedicle screw instrumentation is currently the “gold standard” in scoliosis surgery. However, placement of pedicle screws in thoracic spine is considered challenging. Previous studies have described morphometric changes in the pedicle when a larger screw is inserted, with pedicle expansion preceding screw cutout and pedicle fracture. We report an unusual case of neurological deficit due to cord compression by an expanded pedicle following pedicle screw insertion on the concave side of the apical vertebra in a 14-year-old patient with Lenke Type 3C(-) adolescent idiopathic scoliosis. Identification of the expanded pedicle as the cause of neurological symptoms, prompt action, and deferring the corrective surgery while accepting less correction helped us in negotiating the problem without causing permanent neurological deficit. Pedicle expansion in an immature spine can cause neurological complications. The screw diameter at the apical vertebrae on the concave side should be carefully selected.

Background: Many spinal vertebral anoma­lies often occur, both scoliosis and kyfosis. In scoliosis, congenital abnormalities caused by hemivertebrae are the most common cause of abnormalities. The choice of treatment used can be either non-operative or operative. How­ever, non-operative treatment does not show satisfactory results to prevent the development of deformity. Operative treatment is an option that is considered to indicate more satisfying results. A variety of procedures such as in-situ posterior or with or without instrumentation anteroposterior fusions, combined anterior and poste­rior convex hemiepiphysiodesis and hemi­arthrodesis, and hemivertebral excision with fusion. Fusi In-situ posterior is a procedure option that is considered more beneficial for both surgeons and patients. This study aimed to evaluate the fusi in situ posterior for conge­nital scoliosis with wedge hemivertebrae using single rod and pedicle screw instrumentation in girl 2 year old. Case Presentation : Girl 2 year old with wedge hemivertebrae operated with fusion in situ posterior using single rod and pedicle screw instrumentation. Results: The operative treatment was per­formed on 2 hours operation time with amount of bleeding produced is 80 cc. There were no cranckshaft phenomena and no clinical and radological features suggestive of spinal ste­nosis. There were no major vascular or neuro­gical complications related to the pedicle screws. Then patient wore body jacket for limitation movement before fusion. Conclusion: Posterior situ fusion is perform­ed as convex fusion to avoid curve progression. Fusion in situ posterior using single rod and pedicle screw instrumentation. In congenital scoliosis is minimal blood loss, less traumatic, simple, safe and effective procedure. This study showed the early fusi in situ posterior of conge­nital scoliosis structural changes occur above or below can reduce fusion length, prevent curve progression and effectively achieve a more satisfactory correction without hazardous iatro­genic spinal stenosis, crankshaft phenomena, or neurological complications. Further research is needed to assess the progress of the outcome of surgery Keyword s : congenital scoliosis, wedge hemi­vertebrae, convex, fusi in situ posterior Correspondence: Pamudji Utomo. Department of Orthopaedic & Traumatology, Faculty of Medicine, Universitas Sebelas Maret/ Prof. Dr. R. Soeharso Ortho­pae­dic Hospital, Surakarta Indonesian Journal of Medicine (2020), 05(02): 125-130 https://doi.org/10.26911/theijmed.2020.05.02.05

Pedicle screw instrumentation is a fundamental technique in lumbar spine surgery. However, several complications could occur when placing a pedicle screw, the most serious being damage to the neural structures. We developed an attachable magnetic nerve stimulating probe used for triggered electromyography (t-EMG) to avoid these. This study aimed to investigate the efficacy of this probe for intraoperative neuromonitoring (ION) during lumbar pedicle screw placement in a porcine model. Forty pedicle screws were inserted bilaterally into the pedicles of the fourth and fifth lumbar vertebrae of five pigs, 20 were inserted typically into the pedicle without nerve damage (Group A), and the other 20 were inserted through the broken medial wall of the pedicle to permit contact with the neural structures (Group B). We measured the triggered threshold for pedicle screw placement through the conventional nerve probe and our newly developed magnetic probe. There was no significant difference in the triggered threshold between the two instruments (p = 0.828). Our newly developed magnetic stimulating probe can be attached to a screwdriver, thus preventing real-time screw malpositioning and making it practical and equally safe. This probe could become indispensable in revision spine surgeries with severe adhesions or endoscopic spine surgeries.

Objective . To assess risk factors for the imbalance of the shoulder girdle and to identify reproducible X-ray criteria for persistent shoulder imbalance after correction of idiopathic scoliosis. Material and Methods . A total of 94 patients with idiopathic scoliosis were included in the retrospective study. All patients underwent primary posterior correction of the deformity using pedicle screw instrumentation. Radiography of the spine throughout its length was performed before surgery, in the early postoperative and in the long-term (at least 12 months after surgery) periods. The shoulder imbalance was considered clinically significant with radiographic shoulder height difference more than 2 cm. Results . A significant decrease in the magnitude of all curves after surgery and in the long-term period was noted. The magnitude of the proximal curve decreased from 25.38° ± 15.89° to 14.51° ± 8.17° (p < 0.0001) and to 14.29° ± 8.25° (p = 0.24); the main thoracic curve from 59.33° ± 20.76° to 20.096° ± 9.89° (p < 0.0001) and to 20.87° ± 9.48° (p = 0.19); and thoracolumbar curve from 47,20° ± 15,99° to 15.69° ± 8.66° (p < 0.0001) and to 16.98° ± 7.6° (p = 0.01), respectively. The shoulder imbalance was recorded in 27 patients (28.72 %) after surgery and in 13 (13.83 %) – in the long-term period. In these patients, various Lenke types of deformity were presented. A correlation of the distal adding-on phenomenon with self-correction of the shoulder balance is revealed (r = 0.56; p < 0.005). Persistent shoulder imbalance correlated with presence of a structural proximal thoracic curve (p = 0.041642), residual proximal curve magnitude after surgery (r = 0.22; p = 0.03), and presence of a symptom of double rib hump on radiographs after surgery (r = 0.75; p ≤ 0.005). Conclusion . The most characteristic pattern of persistent shoulder imbalance is the presence of asymmetry in the proximal and main regions of the chest. This sign can be detected by intraoperative lateral radiography of the spine, which will allow the surgeon to take measures to eliminate this phenomenon and reduce the probability of persistent shoulder imbalance development.

To analyze the effects of direct vertebral rotation (DVR) on radiologic outcomes in the treatment of thoracic adolescent idiopathic scoliosis after selective thoracic fusion with pedicle screw instrumentation.Adolescent idiopathic scoliosis patients with single thoracic curves (n = 110) treated by selective thoracic fusion with a minimum of 2 years of follow-up were retrospectively analyzed. The patients were separated into 2 groups: non-DVR (n = 63) and DVR (n = 47).There was a significant difference in fused segments between the non-DVR and DVR groups (P0.001). There was also a significant difference in main thoracic curve postoperatively (P = 0.001) and at the last follow-up (P = 0.006) between the non-DVR and DVR groups. However, there was no significant difference in proximal thoracic and lumbar curves postoperatively (proximal thoracic curve: P = 0.186; lumbar curve: P = 0.155) and at the last follow-up (proximal thoracic curve: P = 0.250; lumbar curve: P = 0.060) between the 2 groups. Significant improvements in the lowest instrumented vertebra tilt and disc angle were noted but then slight deteriorations in such were observed during the follow-up period in the non-DVR group. The prevalence of unsatisfactory results was 20.6% (13 of 63) in the non-DVR group and 19.1% (9 of 47) in the DVR group, with no significant difference (P = 0.522).For correcting single thoracic adolescent idiopathic scoliosis by selective thoracic fusion with pedicle screw instrumentation, the addition of DVR to the surgical procedure showed comparable radiologic outcomes compared with non-DVR procedures.

Previous finite element studies of thoracolumbar fractures were mostly based on simulation analysis of one single object, which was difficult to objectively evaluate the differences between conventional pedicle screws and Schanz pedicle screws. The aim of this study was to evaluate the stress of screw and injured vertebrae displacement using the finite element model of conventional pedicle screw and Schanz pedicle screw instrumentation for the treatment of lumbar 1 fractures. Data of eight healthy volunteers were used to simulate the finite element model. The instrumentation models were divided into four groups: moderate fracture conventional (MC), moderate fracture Schanz (MS), unstable/severe fracture conventional (UC), and unstable/severe fracture Schanz (US) pedicle screw groups. The maximum screw stress and lumbar 1 displacement/micro-motion in each group increased with the increase of torque and/or load. Under the same fracture, maximum von Mises stress of conventional pedicle screw (MC/UC) was larger than Schanz pedicle screw (MS/US) (P

STUDY DESIGN This was a retrospective comparative study. OBJECTIVE To evaluate long-term outcomes of selective thoracic fusion (STF) using both rod derotation (RD) and direct vertebral rotation (DVR) with pedicle screw instrumentation (PSI) in the treatment of thoracic adolescent idiopathic scoliosis (AIS) with a minimum 10-year follow-up. SUMMARY OF BACKGROUND DATA Postoperative compensation and maintenance of the unfused lumbar curve after STF is very important factor for the satisfactory results in the treatment of thoracic AIS. PATIENTS AND METHODS Sixty-five patients with thoracic AIS treated with STF from the neutral vertebra (NV) to NV or NV-1 with RD and DVR were retrospectively analyzed with a minimum 10-year follow-up. Patients were divided into 2 groups: satisfactory (n=52) and unsatisfactory groups (n=13). Unsatisfactory results were defined as an adding-on, a lowest instrumented vertebra (LIV) tilt of >10 degrees, or coronal balance >15 mm. RESULTS No significant differences were observed in the main thoracic curve between the satisfactory and unsatisfactory groups postoperatively (P=0.218) and at the last follow-up (P=0.636). Significant improvements of LIV tilt and disk angle were observed in both groups, but these improvements deteriorated during the follow-up period in the unsatisfactory group. Significant differences of apical vertebra (AV) and end vertebra (EV) were observed postoperatively (AV: P=0.001, EV: P=0.001) and at the last follow-up (AV: P

Growing rod surgery for skeletally immature patients helps correct severe scoliosis while allowing continued spinal column growth. Previous reports have studied vertebral body changes following growing rod surgery, but there are currently no published reports on alterations in pedicle morphology. Given the potential need for definitive spinal fusion with pedicle screw instrumentation, an awareness of changes in pedicle morphology is critical. A morphometric analysis of pedicles was performed using 3D reconstructions of 3 CT scans (preoperative and at 3 and 6 years) obtained in a young girl with infantile idiopathic scoliosis (T7 apex) who underwent unilateral rib-to-spine growing rod (2nd–4th ribs to L1) implantation with lengthening every 6 months for 6 years. The pedicle widths on the growing rod side from T5 to T9 (apex ± 2) were all smaller at 6 years postoperatively than preoperatively, while the same-level pedicles opposite the device significantly increased in width. These findings support anecdotal intraoperative reports by surgeons and provide evidence of pedicle stress shielding due to growing rod distraction and force deprivation.

Cervical spine instrumentation is evolving with an aim of stabilizing traumatic and non-traumatic cases of the cervical spine with a beneficial reduction, better biomechanical strength, and a strong construct with minimal intraoperative, as well as immediate and late postoperative complications. The evolution from interspinous wiring till cervical pedicle screws has changed the outlook in treating the cervical spine pathologies with maximum 3D stability, decreasing the duration of postoperative immobilization and hospital stay. Some complications associated with the use of cervical pedicle screw can be catastrophic. This review article discusses the morphometry of cervical pedicle; indications, biomechanical superiority, tricks, and pitfalls of cervical pedicle screw; complications and technical advancements in targeting safe surgery; and future directions of cervical pedicle screw instrumentation.

Background: Pedicle screw instrumentation of the posterior cervical spine is the most secure form of fixation available to surgeons. It has not achieved widespread use yet in the Middle East, mostly due to concerns regarding its feasibility in the target population. A detailed morphometric analysis of the lower cervical spine pedicles using computerized tomography (CT) was proposed to address this issue. Methods: Two hundred and seventy patients were enrolled in the study. CT scans were reviewed by two experienced assessors, and measurements of pedicle width (PW), height (PH), and transverse angle (TA) were recorded for all patients. Interobserver and intraobserver reliability were calculated using the kappa statistic. Sex differences were also recorded and analyzed. The t test was used to assess for any significant differences in measurements due to sex (P Results: The mean PW varied from 4.4 mm in C3 to 6.1 mm in C7. The mean PH was 6.4 mm in C3 and 6.8 mm in C7. Pedicle TA varied from 42 to 51 degrees between the different levels. Sex differences were observed and were statistically significant for PW and PH. Interobserver reliability was high for PW and PH, but was low for TA. Intraobserver reliability was 0.99 for both assessors. Conclusion: This study provides reliable PW and PH measurements and demonstrates that cervical pedicle screw instrumentation is feasible in our local population. Significant variability exists, however, and each patient must be addressed individually for best results. Level of Evidence: 3. Clinical Relevance: This study shows that the morphology of the subaxial cervical pedicle permits instrumentation in a majority of cases of our target population.

The cortical bone trajectory (CBT) has been introduced with the aim of better screw hold, however, screw-rod constructs with this trajectory might provide less rigidity in lateral bending (LB) and axial rotation (AR) compared to the constructs with the traditional trajectory (TT). Therefore, the addition of a horizontal cross-connector could be beneficial in counteracting this possible inferiority. The aim of this study was to compare the primary rigidity of TT with CBT screw-rod constructs and to quantify the effect of cross-connector-augmentation in both. Spines of four human cadavers (T9 –L5) were cropped into 15 functional spine units (FSU). Eight FSUs were instrumented with TT and seven FSUs with CBT pedicle screws. The segments were tested in six loading directions in three configurations: uninstrumented, instrumented with and without cross-connector. The motion between the cranial and caudal vertebra was recorded. The range of motion (ROM) between the CBT and the TT group did not differ significantly in either configuration. Cross-connector -augmentation did reduce the ROM in AR (16.3%, 0.27°, p = 0.02), LB (2.9%, 0.07°, p = 0.03) and flexion-extension FE (2.3%, 0.04°, p = 0.02) for the TT group and in AR (20.6%, 0.31°, p = 0.01) for the CBT-group. The primary rigidity of TT and CBT single level screw-rod constructs did not show significant difference. The minimal reduction of ROM due to cross-connector-augmentation seems clinically not relevant. Based on the findings of these study there is no increased necessity to use a cross-connector in a CBT-construct., PLoS ONE, 16 (6), ISSN:1932-6203

To evaluate whether adding an extra anchoring point to the construct by passing the crosslink through a hole in the spinous process (trans-spinous crosslink technique), may prevent screw loosening by increasing the pull-out strength.Twenty-four fresh-frozen single lumbar sheep vertebrae were instrumented with pedicle screws bilaterally, and they are connected to each other with a crosslink. All vertebrae were assigned randomly to either the experiment (trans-spinous crosslink) group or the control group. In the experiment group, the crosslink was passed through a hole within the spinous process. In the control group, the posterior part of the hole was removed. The pull-out force of the construct was determined using a mechanical testing machine.The mean pull-out forces of the experiment group and the control group were 1949 ± 361.55 N and 1338.57 ± 220.26 N, respectively. The pull-out force of the experiment group was significantly higher than those of the control group with 99.9% confidence (p0.001).The pedicle screws rigidly anchor the internal fixation devices to the vertebral colon. In classical construct design, pedicle screws share the load. Adding extra anchoring points decreases screw share and may prevent construct pull-out. This study shows that the trans-spinous crosslink can serve as an anchoring point and increases the construct pull-out strength.

Background Bony fusion rate was significantly lower in patients with type 3 Modic change than patients with normal endplates. It is not known whether there are relevant differences in fusion efficiency among patients with type 2 sclerotic Modic change or non-sclerotic Modic change, or no Modic change. Methods A retrospective study contained 196 lumbar segments in 123 subjects undergoing posterior lumbar interbody fusion (PLIF) with pedicle screw instrumentation (PSI) to assess the effect of type 2 sclerotic Modic change on fusion efficiency. These endplates were allocated into groups A, B, and C, according to their Modic changes. Group A had endplates with type 2 Modic change and endplate sclerosis. Group B had type 2 Modic change without endplate sclerosis. Group C had neither Modic change nor endplate sclerosis. The presence of Modic change was determined by magnetic resonance imaging (MRI). Endplate sclerosis in type 2 Modic change was detected by computed tomography (CT) before the operation. We collected CT data 3 months to more than 24 months after operation in patients to assess bony fusion. Results Incidences of bony fusion were 58.8% in group A, 95.0% in group B, 94.3% in group C. The bony fusion rate was significantly lower in group A than in either group B or C. There was no significant difference between groups B and C. Thus, endplates with type 2 sclerotic Modic change had a lower fusion rate in patients undergoing PLIF with PSI. Conclusion Type 2 sclerotic Modic change could be an important factor that affects solid bony fusion in patients undergoing PLIF with PSI. CT may help diagnose endplate sclerosis in patients with type 2 change and inform the choice of the best site for spinal fusion.

Highlights • Mean major coronal correction rate was 67%. • Pedicle screws provide three-dimensional deformity correction. • Posterior spinal fusion alone (PSF) obtains a good and stable correction for severe scoliosis., Introduction Adolescent idiopathic scoliosis (AIS) can lead to severe deformity. However, early detection and treatment can prevent its progression. Surgical instrumentation for scoliosis treatment has evolved from Harrington instrumentation to pedicle screws. However, there are still some concerns about the efficacy and long-term effects of pedicle screw fixation, and the clinical and radiographic outcomes of surgical treatment for severe AIS (>90°) by posterior spinal fusion alone need to be established. Presentation of case Eight patients with severe and rigid idiopathic scoliosis were recruited for this study. All surgeries were performed by one senior spine surgeon between 2015 and 2018. Free hand technique, intraoperative neurophysiologic monitoring (IONM), and intraoperative fluoroscopy to assess the screw position was performed. Discussion Severe scoliosis results in a complex three-dimensional spinal deformity that often requires correction in multiple planes. Mean major coronal correction rate was 67% (45–80%). No major complications occurred during the perioperative period and after one year follow up. Conclusion Pedicle screws provide three-dimensional deformity correction. There were no complications other than the low-grade late implant-associated infections. Posterior spinal fusion with pedicle screw-only instrumentation obtains a good and stable correction for severe scoliosis.

OBJECTIVE: A retrospective multicenter comparative study was carried out to evaluate whether pregnancy leads to the loss of deformity correction (LOC) in female patients surgically treated for idiopathic scoliosis. METHODS: A total of 128 female patients who underwent segmental spinal instrumentation and fusion for adolescent idiopathic scoliosis (AIS) between 1999 and 2014 were reviewed. Of these patients, 62 became pregnant (surgery-pregnancy group [SPG]), whereas 66 did not (surgery-nonpregnancy [SNP] group). Radiographic parameters were analyzed before surgery, after surgery, before pregnancy, up to 1 year after delivery, and at final follow-up (FFU). Health-related quality of life was analyzed using the Scoliosis Research Society outcome questionnaire (SRS-22r). RESULTS: The mean age at the time of surgery was 16 years in both groups. The mean preoperative major curves were 65 degrees (standard deviation [SD], 12 degrees) versus 67 degrees (SD, 11 degrees), 18 degrees (SD, 9 degrees) versus 17 degrees (SD, 9 degrees) immediately after surgery, and 20 degrees (SD, 8 degrees) versus 20 degrees (SD, 8 degrees) at FFU in the SPG and SNP groups, respectively (P > 0.10 for all comparisons). The mean loss of correction was 3.5 degrees (SD, 3 degrees) in the SPG and 4.5 (SD, 3 degrees) for SNP groups, respectively (P = 0.379). The mean preoperative thoracic kyphosis (T5-T12) was 26.5 degrees (SD, 11.9 degrees) for SPG and 24.7 degrees (SD, 14.5 degrees) for SNP, after surgery 19.2 degrees (SD, 9.5 degrees) for SPG, 18.8 (SD, 8.9 degrees) for SNP and at FFU, 20.3 degrees (SD, 9 degrees) for SPG and 21.3 degrees (SD, 8.5 degrees) for SNP. CONCLUSIONS: Women who have undergone pedicle screw instrumentation and fusion who have had >= 1 pregnancies do not have curve progression or deterioration in the longer-term outcomes compared with patients who have not become pregnant.

BACKGROUND As minimally invasive spine surgery becomes more widespread, concerns regarding radiation exposure to surgeons and patients alike have become a growing concern. Robotic guidance has been developed as a way to increase the accuracy of instrumentation while decreasing radiation burden. METHODS A retrospective analysis of a large, multi-centre, prospective study comparing robotic-guided (RG) to fluoroscopic-guided (FG) (Multi-centre, Partially Randomized, Controlled Trial of MIS Robotic vs. Freehand in Short Adult Degenerative Spinal Fusion Surgeries) was performed to evaluate for differences in radiation exposure between study groups. RESULTS RG was associated with 78.3% (p

Background and Objectives. Kaposiform hemangioendothelioma (KHE) is a vascular tumor of very low incidence, which occurs mostly in children and infants. The tumor is recognized for its locally aggressive, yet rarely metastatic behavior. It may cause consumptive coagulopathy known as Kasabach-Merritt phenomenon. We report a distinctive case, where an 11-year-old boy is presented with progressive thoracolumbar scoliosis without any symptom or neurological sign. Case Report. The patient underwent spinal deformity correction via posterior pedicle screw instrumentation and fusion, along with tumor biopsy. The pathology report confirmed KHE. The patient did not show a prominent progression of scoliosis after the surgery without any further treatments. Conclusions. Many of scoliotic patients do not have any apparent cause, thereby regarded as idiopathic scoliosis. The presented case is where kaposiform hemangioendothelioma is likely to be linked to the patient’s scoliosis. We demonstrate the possibility of secondary scoliosis should always be kept in mind of orthopaedic doctors. We also conclude that secondary scoliosis does not show exacerbation after growth completion.

Lateral lumbar interbody fusion (LLIF) is a widely applied and useful procedure for spinal surgeries. However, posterior fixation has not yet been decided. We compared the radiographic and clinical outcomes of unilateral versus bilateral instrumented one-level LLIF for degenerative lumbar disease. We conducted a prospective cohort study of 100 patients, who underwent unilateral (group U) or bilateral (group B) instrumented one-level LLIF for degenerative lumbar disease. Forty-one patients in group U were undergoing unilateral pedicle screw instrumentation, and 59 patients in group B were undergoing bilateral pedicle screw instrumentation. Clinical characteristic and demographic data before surgery were compared. The intraoperative data, including operative time with changes in positions, intraoperative blood loss, and X-ray exposure time, as well as the perioperative data, including postoperative hospital stay and clinical and radiographic data were compared. As a result, Group U required a significantly shorter operating time than group B. The subsidence grade and fusion rates exhibited no significant differences in the postoperative radiographic evaluation. Group U had better results in clinical assessments than group B. However, group U required more additional surgeries owing to complications.

Background Data: Burst fractures are commonly provoked by axial compression which disrupts the anterior column. In this setting, posterior stabilization using pedicle screws alone may lead to delayed kyphosis and instrumentation failure due to inadequate support of the anterior column. Purpose: To evaluate the efficacy of pedicle screw instrumentation combined with transpedicular titanium mesh cage augmentation for treatment of burst fractures. Study Design: Prospective descriptive cohort clinical case study. Patients and Methods: Fourteen neurologically intact patients with acute incomplete thoracolumbar burst fracture (AO type A 3.1), and operated upon through period from January 2016 to June 2017 were included. Patients were treated using a three vertebrae pedicle screw fixation construct combined with bilateral transpedicular titanium mesh cage augmentation of the fracture. Patients were followed for at least one year. Data about pain (VAS), function (ODI) and vertebral body deformity (Beck index and local kyphotic angle) were recorded prospectively. Results: Patients were operated within 5 days after trauma. The mean VAS score improved after surgeryfrom 8.2±1.3 to 3.7±1.1 postoperatively and to 1.8±0.7 at final follow up(P˂0.05). The mean ODI score improved from 69.4±5.2 preoperatively to 17.2±2.4 at final follow up. The mean Beck index improved from 0.63 preoperatively to 0.81 postoperatively and to 0.79 at final follow up. The mean local kyphotic angle improved from 20.4opreoperatively to 11.5opostoperatively and declined to 13.7o at final visit. No patient had neurological deterioration or hardware failure during the follow up.The mean follow up was 13.4±1.8 months. Conclusion: Posterior stabilization using pedicle screw fixation in combination with titanium mesh cage augmentation can maintain vertebral restoration, prevent hardware failure and lead to better clinical outcome. (2018ESJ162)

Background Biomechanical studies revealed that pedicle screw instrumentation has a superior stabilizing effect compared with other internal fixations in reconstructing the subaxial cervical spine. However, severe neurovascular risks preclude surgeons from routinely conducting pedicle screw manipulation in cervical spine. Objective To evaluate the accuracy and safety of the lateral vertebral notch (LVN)-referred technique used in subaxial cervical pedicle screw (CPS) placement. Methods One hundred thirty-five consecutive retrospective patients with cervical disorders underwent the LVN-referred technique for CPS placements in 3 spine centers. Postoperative pedicle perforations were confirmed by CT scans to assess the technical accuracy. Neurovascular complications derived from CPS misplacements were recorded to evaluate the technical safety. Results A total of 718 CPSs were inserted into subaxial cervical spine. Postoperative CT scans revealed that the accuracy of CPS placement was superior. Neither vertebral artery injury nor spinal cord injury occurred. One radiculopathy was from a unilateral C6 nerve root compression. A screw-related neurovascular injury rate of 0.7% occurred in this cohort. Additionally, there was no significant difference in the accuracy of CPS placement among 3 surgeons (H = 1.460, P = .482). The relative standard deviation values revealed that technical reproducibility was acceptable. Furthermore, there was no significant difference between the patients' pedicle transverse angles and inserted CPS transverse angles from C3 to C7 (all P > .05). Conclusion The LVN is a reliable and consistent anatomic landmark for CPS placement. The accuracy and safety of subaxial CPS placement by using LVN-referred technique are highly acceptable, which may endow this technique to be practicably performed in selected patients.

Achieving fixation and fusion across the lumbosacral junction has been a challenge for spinal deformity surgeons ever since the development of instrumentation. The S2 alar-iliac (S2AI) trajectory has been introduced as a method of pelvic fixation to decrease strain on S1 screws. The S2AI screws differ in several ways from traditional iliac screws. The trajectory of these screws helps avoid the use of offset connectors due to the screws alignment with the proximal pedicle screw instrumentation. Current literature shows that S2AI screws are effective with low complication rates, but the path of these screws is intimately associated with major neural and vascular structures. Use of robotic guidance to obtain the correct trajectory has been shown to be both safe and effective in obtaining proper trajectory of S2AI screws with over 95% accuracy. Herein, we report on the technical considerations and radiographic outcomes surrounding robotic and freehand insertion of S2AI screws.

OBJECTIVE Thoracic pedicles have special and specific properties. In particular, upper thoracic pedicles are positioned in craniocaudal plane. Therefore, manipulation of thoracic pedicle screws on the left side is difficult for right-handed surgeons. We recommend a new position to insert thoracic pedicle screw that will be much comfortable for spine surgeons. METHODS We retrospectively reviewed 33 patients who underwent upper thoracic pedicle screw instrumentation. In 15 patients, a total of 110 thoracic pedicle screws were inserted to the upper thoracic spine (T1-6) with classical position (anesthesiologist and monitor were placed near to patient's head. Surgeons were standing classically near to patient's body while patients were lying in prone position). In 18 patients, a total of 88 thoracic pedicle screws were inserted to the upper thoracic spine with the new standing position-surgeons stand by the head of the patient and the anesthesia monitor laterally and under patient's belt level. All the operations performed by the same senior spine surgeons with the help of C-arm. Postoperative computed tomography scans were obtained to assess the screw placement. The screw malposition and pedicle wall violations were divided and evaluated separately. Cortical penetration were measured and graded at either : 1-2 mm penetration, 2-4 mm penetration and >4 mm penetration. RESULTS Total 198 screws were inserted with two different standing positions. Of 198 screws 110 were in the classical positioning group and 88 were in the new positioning group. Incorrect screw placement was found in 33 screws (16.6%). The difference between total screw malposition by both standing positions were found to be statistically significant (p=0.011). The difference between total pedicle wall violations by both standing positions were found to be statistically significant (p=0.003). CONCLUSION Right-handedness is a problem during the upper thoracic pedicle screw placement on the left side. Changing the surgeon's position standing near to patient's head could provide a much comfortable position to orient the craniocaudal plane of the thoracic pedicles.

STUDY DESIGN Description of a navigated, single-step, minimally invasive technique for the placement of pedicle screws. OBJECTIVE To describe a new technique for minimally invasive placement of pedicle screws in the lumbar spine using O-arm and StealthStation navigation in combination. SUMMARY OF BACKGROUND DATA Minimally invasive surgical techniques are described in the literature as safe and effective methods for pedicle screw instrumentation. These techniques increase radiation exposure and prompt multiple instrument passes through the pedicle. MATERIALS AND METHODS In total, 35 adult patients (187 screws) underwent lumbar surgery with pedicle screw placement using the 1- (8 patients/48 screws) or 2-step (27 patients/139 screws) technique. Complications associated with instrumentation were noted. Pedicle screw position was evaluated. RESULTS Of 187 screws placed, 181 (96.8%) were found to be fully contained within the pedicle (grade 1) and 4 (2.1%) had a breach of

C1 pedicle screw instrumentation is a recently documented technique, which may have benefits over other more popularised procedures, however it may not be possible in all patients. This study aims to investigate the applicability of the C1 pedicle screw technique to a cohort of patients through assessment of radiological parameters. A retrospective review of 150 consecutive patients undergoing computer tomography (CT) of the cervical spine was performed. Based on defined parameters images were assessed for feasibility of placement of pedicle screws. C1 pedicle height (PH), pedicle width (PW), screw trajectory length (LML) and width (LMW) were recorded with PH ≥ 4 mm defined as the primary outcome measure. A total of 115 patients and 230 C1 pedicles were examined. The mean PH was found to be 5.1 mm. 207 pedicles were deemed suitable for placement of pedicle screw instrumentation. Overall C1 pedicle screw instrumentation was deemed possible in 94.6% of male pedicles and 84% of female pedicles. C1 pedicle screw instrumentation is feasible to be performed in more than 90% of the patients.

Despite proven biomechanical superiority and resultant superior clinical outcomes, pedicle instrumentation in cervical spine is not widely practiced due to technical difficulties, steep learning curve, and possible potential catastrophic complications due to screw misplacement. This study was undertaken with the purpose to evaluate the feasibility, accuracy, and complications of cervical pedicle screw instrumentation solely using O-arm-based 3D navigation technology.Prospectively maintained data from a single-surgeon case series were retrospectively analyzed. All the patients had undergone cervical pedicle instrumentation under O-arm 3D navigation. Screw placement accuracy was analyzed and compared among different vertebral levels and also between different patient groups.A total of 241 cervical pedicle screws were inserted in 44 patients. Out of the 241 screws, 197 (81.74%) were inserted at the level of C3-C6 vertebrae with nearly equal distribution among the 4 vertebrae, followed by 32 (13.28%) and 12 (4.98%) screws at C2 and C7 vertebrae, respectively. After the analysis of screw placement as per Gertzbein classification, the overall breach rates were found to be 7.05% (17 screws) with 52.94% (10 screws) Grade I, 47.06% (7 screws) Grade II, and nil Grade III screw breaches.The use of O-arm-based intra-operative 3D scans for navigation can make cervical pedicle screw placement reliable. High accuracy and better intra-operative control can increase surgeon's confidence in using cervical pedicle instrumentation on more regular basis. These slides can be retrieved under Electronic Supplementary Material.

Introduction: The anatomical studies conducted in recent decades made possible the emergence of “free-hand” technique for pedicle screw instrumentation of the thoracic-lumbar spine based solely on anatomical parameters. However, the potential risks associated with such technique revealed the immediate need to create educational models for surgical training. Methods: After an interdisciplinary partnership, two anatomicspecimens were submitted to instrumentation of the thoracolumbar spine. In the sequence they were submitted to fine-slice CT-scan, and, finally, to the decompression of the lumbar spinal canal in order to verify the accuracy pedicle screw placement both on the anatomical and radiological level. Results: Overall, 28 intact vertebral bodies were instrumented (T5-S1) in two specimens (a total amount of 62 pedicle screws). Overall, there were only four critical perforations. Considering the accuracy rates for each specimen separately, the number of violations decreased from the first (32% of misplaced screws) to the second instrumented specimens (25%). A more surprising learning curve was noted when considering the lower thoracic spine separately (37,5% versus 12,5%). Conclusions: The authors demonstrate that incorporating the training of pedicle screw instrumentation in routine neurosurgical residency is a cost-effective educational method, which enables young neurosurgeons to practice these skills in the laboratory before proceeding to the operating room.

Background Injury of the ureter is a potentially devastating complication most often reported in gynecologic, colorectal, or vascular pelvic surgery or endoscopic procedures for ureteric diseases. We report a rare case of ureteral rupture occurring as a complication of percutaneous pedicle screw placement. Case Description A 60-year-old man reported unbearable abdominal pain on the day after right L4-L5 transforaminal intervertebral fusion and percutaneous pedicle screw placement. A computer tomography workup showed contrast media extravasation outside the excretory system consistent with a left ureteral traumatic perforation. The patient underwent left nephrostomy and a double-J stent insertion and subsequently fully recovered. The ureter completely healed, enabling stent removal 5 months later. Methods PubMed and EMBASE were screened for ureteral injury caused by posterior lumbar surgery. Results We found 27 other reports with only 1 other case after minimally invasive transforaminal lumbar interbody. Conclusions Complications of minimally invasive pedicle screw placement are often described as dural tear of neurologic impairment. This report shows that unexpected side effects are still possible and spine surgeons should be aware especially when performing minimally invasive procedures, in which, by definition, pedicles are concealed from direct visualization.

Several studies have reported incidence and risk factors for the development of proximal junctional kyphosis (PJK) in patients with adolescent idiopathic scoliosis (AIS). However, there is little information regarding long-term follow-up after pedicle screw instrumentation (PSI) with rod derotation (RD) and direct vertebral rotation (DVR). Sixty-nine AIS patients who underwent deformity correction using PSI with RD and DVR were retrospectively analyzed in two groups according to the occurrence of PJK, with a minimum five-year follow-up, including a non-PJK group (n = 62) and PJK group (n = 7). Radiological parameters were evaluated at preoperative, postoperative, and last follow-up. Incidence for PJK was 10.1% (7/69 patients), with a mean 9.4-year follow-up period. The thoracolumbar/lumbar curve (TL/L curve) was proportionally higher in the PJK group. The proximal compensatory curve was significantly lower in the PJK group than in the non-PJK group preoperatively (p = 0.027), postoperatively (p = 0.001), and at last follow-up (p = 0.041). The development of PJK was associated with the TL/L curve pattern, lower preoperative proximal compensatory curve, and over-correction of the proximal curve for PSI with RD and DVR. Therefore, careful evaluation of compensatory curves as well as of the main curve is important to prevent the development of PJK in the treatment of AIS.

Pedicle screw instrumentation (PSI) through posterior approach has been the mainstay of deformity correction for adolescent idiopathic scoliosis (AIS). However, changes in the quantity of paraspinal muscles after AIS surgery has remained largely unknown. The aim of this study was to investigate long-term follow-up changes in paraspinal muscle volume in AIS surgery via a posterior approach. Forty-two AIS patients who underwent deformity correction by posterior approach were analyzed through a longitudinal assessment of a cross-sectional area (CSA) in paraspinal muscles with a minimum five-year follow-up. The CSA were measured using axial computed tomography images at the level of the upper endplate L4 by manual tracing. The last follow-up CSA ratio of the psoas major muscle (124.5%) was significantly increased compared to the preoperative CSA ratio (122.0%) (p &lt, 0.005). The last follow-up CSA ratio of the multifidus and erector spine muscles significantly decreased compared to the preoperative CSA ratio (all p &lt, 0.005). The CSA ratio of the erector spine muscle was correlated with the CSA ratio of the psoas major (correlation coefficient = 0.546, p &lt, 0.001). Therefore, minimizing the injury to the erector spine muscle is imperative to maintaining psoas major muscle development in AIS surgery by posterior approach.

Minimally invasive fusion techniques for degenerative lumbar pathology commonly involve the placement of pedicle screws. Percutaneous placement of these screws allows the surgeon to minimize soft tissue trauma, improving postoperative recovery for patients. This review will cover the indications and techniques for percutaneous pedicle screw instrumentation of the lumbar spine, and will highlight the advantages and potential contraindications to using percutaneous instrumentation.

STUDY DESIGN A comparative study of facet joint violation (FJV) using two percutaneous surgical techniques. OBJECTIVE To compare the rate of iatrogenic FJV and medial pedicle wall breach between two methods of percutaneous pedicle screw instrumentation in the thoracic and lumbar spine. SUMMARY OF BACKGROUND DATA Variable iatrogenic damage to the facet joints has been reported to occur with percutaneous pedicle screw techniques, compared with the open approach, which has been associated with adjacent segment disease. Technical variations of percutaneous pedicle screw placement may pose different risks to the facet joint. METHODS Attending spine surgeons percutaneously placed pedicle screws in seven human cadaveric spines from T2 to L5. At each level, screws were instrumented on one side using the 9 or 3 o'clock reference point of the pedicle on the posteroanterior view with a lateral-to-medial trajectory (LMT) and on the contralateral side using the center of the pedicle with an owl's eye trajectory (OET). Postoperative screw placement was assessed with computed tomography and then open cadaveric dissection. Outcome measures included FJV and medial pedicle wall breach. RESULTS Overall, 17 of 105 screws placed with an LMT versus 49 of 105 screws placed with an OET violated or abutted the facet joint (P

Introduction: Use of pedicle screw (PS) systems for spinal stabilization has become increasingly common in spine surgery. The technique and principle for pedicle screw instrumentation as well as anatomical landmarks of screw placement, however are common to all systems. The purpose of this study is to compare accuracy of pedicle screw placement with conventional and navigation techniques. Aim: To compare the accuracy of pedicle screw positioning between conventional and a new navigation system for the spine. Materials and Methods: It was a retrospective study in which 40 patients were randomly selected during the period between Jun-2014 to Jun-2016, operated for posterior fixation either through conventional and navigational spine surgery. Two independent observers analysed digital axial CT slices of all instrumented pedicles, with individual and consensus interpretation for each screw. A simple grading system (LAINE’s grading) was devised for evaluation of screw position. Results and Discussion: Overall accuracy of navigation technique is 95.89% (140/146) with 6 PS breach with laine’s grade 1 error all occurs in thoracic level, doesn’t results into any type of complications in manner of neurologic deficit or CSF leakage or dural tear etc. Overall accuracy of conventional PS placement is 89.84% (113/128) with 4 PS having grade 2 error and 11 PS having grade 3 error mainly occurs in thoracic level but none causes complication in any form i.e.; neurologic deficit, CSF leak, revision surgery etc. Conclusion: From our study, despite of high cost, preoperative registration and matching, more steep learning curve, needful of technician throught surgery, navigation surgery is better option in thoracic PS placement and spinal deformities due to complex morphology and anatomy of thoracic pedicles with rib cage obscuring fluoroscopic visualization making conventional surgery difficult with high rate of pedicle breach.

Type of study: Retrospective study Objectives: To evaluate correlation between flexibility, implant density on curve correction in adolescent idiopathic scoliosis Materials and methods: We retrospectively reviewed all consecutive patients of adolescent idiopathic scoliosis who underwent single stage posterior-only correction and instrumented spinal fusion at a single centre between 2013 and 2015 performed by single surgeon. All cases of adolescent idiopathic scoliosis treated with all pedicle screw instrumentation were included. A total of 30 patients were studied, which included 20 females and 10 males. Correlation between implant density, flexibility and curve correction was investigated with pearson correlation coefficient. Results: Average flexibility was 41.86%. Average implant density for rigid curves was 54.49%, flexible curves was 58%. Average curve correction for rigid curve was 60.22%, flexible curves79.56%.The correlation coefficient for curve correction and implant density was 0.096 for flexible curves, 0.075 for rigid curves, both were statistically not significant. The correlation coefficient for flexibility and curve correction was 0.578 for flexible curves and 0.506 for rigid curves which was statistically significant for rigid curves. Conclusion: There was minimal positive correlation correlation between implant density and curve correctability in both flexible and rigid curves not statistically significant. There is positive correlation between flexixibility & curve correctability in both flexible and rigid curves which is significant in rigid curves.

Background: Cement-augmented pedicle screw instrumentation (CAPSI) has been found to significantly increase the pedicle screws anchorage in the osteoporotic vertebral body, however, with the increase of augmented level and bone cement dose, the incidence of cement leakage (CL) or side complication of CAPSI also increased. But the effect and potential risks of CAPSI for osteoporotic lumbar degenerative diseases (LDD) have not been investigated in the cases of multiple segment fixation. The purpose of this study was to investigate potential complications of using cement-augmented screws for multilevel fixation (three or four levels) and the effectiveness of this method for treating LDD with low bone quality.Methods: Our clinical database was reviewed for osteoporotic patients who using CAPSI or conventional pedicle screw (CPS) for multilevel fixation (three or four levels) between February 2010 to February 2017. A total of 93 patients with multilevel LDD were divided into the CAPSI group (46 subjects) and the CPS group (47 subjects), including 75 cases for three levels (L2-L5 21 cases、L3-S1 54 cases), 18 cases for four levels (L1-L5 2 cases、L2-S1 16 cases), and the average follow-up was 33.72±18.78 months (range: 24-108). Relevant data were recorded, including age, gender, body mass index (BMI), bone mineral density (BMD), diagnosis, fusion methods, bone graft, fusion level, lumbosacral fixation, different patterns of S1 pedicle screw placement, operation time, blood loss, hospital stay, complications, CL, pulmonary cement embolism (PCE), screw loosening and nonunion patients. Besides, the visual analogue scale (VAS) and Oswestry disability index (ODI) at pre-operation, post-operation, and follow-up were also assessed.Results: In the CAPSI group, a total of 336 augmented screws were placed bilaterally, and the average injection dose of bone cement was 1.85±0.65 ml (range: 1-4). The CL was observed in 44 patients (95.65%) and 116 screws (34.52%). Three cemented screws (0.89%) and twenty-four S1 conventional screws (44.44%) were found loosening during the follow-up and the overall fusion rate was 93.47%. For perioperative complications, two patients (4.35%) experienced PCE, one patient augmented vertebral fracture and three patients (6.52%) wound infection. And in the CPS group, seventeen patients (36.17%) and thirty-three screws (8.46%) suffered loosening in cranial or caudal segments (seven cranial cases and twenty-six of caudal), four cases experienced nonunion, the fusion rate was 91.49% in total. The operation time and hospital stay were longer in CAPSI group, but with a lower percentage of screw loosening (P＜0. 05). And in terms of blood loss, perioperative complications, fusion rate, VAS and ODI scores at the follow-up times, no significant differences were found between the two groups.Conclusions: Patients with osteoporotic LDD underwent CPS at multiple segments have a high rate of screw loosening in the cranial and caudal segment. The application of cemented pedicle screws on multilevel LDD can achieve better stability and less screw loosening, but it also accompanied by longer operating time, higher incidence of CL, PCE and wound infections. Selective cement-augmenting the cranial and caudal pedicle screws may be a worthy strategy to decrease the complications.

Introduction: The dorso lumbar segment of spine (D10 to L2) is an unstable between fixed dorsal and mobile lumbar spine. The Hartshill rectangle fixation is a modification spinal instrumentation fixation. The rectangle formed allows it to fit snugly against the lamina and provides good rotational stability. While Pedicle screw instrumentation also place instrumentation within the spinal canal thus lessens the risk of neural injury. Aim: Is to comparative evaluation of pedicular screw fixation and hartshill ring in dorsolumbar spinal injuries in terms of stability, functional outcome and postoperative complications. Materials and method: Total no of patients was 50 (25 each). Conclusion: Hartshill ring fixation is safe and simpler method, however pedicular screw fixation require more instruments, but it is more firm and and stable fixation.

This chapter describes percutaneous lumbar fusion techniques, including advantages and disadvantages, techniques, complications, and patient selection strategies. Pedicle screw instrumentation can be utilized to stabilize fusion for various spinal pathologies via the creation of a rigid and stable construct. Recent developments in instrumentation have enabled preservation of muscles, ligaments, and bony structures of the spine that help facilitate recovery and improve outcomes. Furthermore, percutaneous techniques preserve muscle and ligaments adjacent segment disease. With these advances in percutaneous pedicle instrumentation and numerous advantages over the traditional method, interest in this approach has and will continue to rise.