Pedicle Screw Insertion Research Articles

Do 3D printed templates aid in exposure, improve the accuracy and safety of pedicle screw insertion in complex spinal kypho-scoliotic deformities? A comparative cohort study

Do 3D printed templates aid in exposure, improve the accuracy and safety of pedicle screw insertion in complex spinal kypho-scoliotic deformities? A comparative cohort study

Crossed Intralaminar Screws for Fusion of the Cervicothoracic Junction and the Thoracic Spine: The Experience in an Iberic Service with Case Series and Review of the Current Literature with Technique Description

The treatment of pathologies in the thoracic spine is a challenge. The periodic failure of pedicle screw insertion and anatomical variations make the search for an alternative to pedicle screws in thoracic spine surgery necessary. The interlaminar crossed screws is a well-known and secure method for fusion in cervical spine, and in thoracic spine there used to be insufficient clinical data to support this technique, until now. We demonstrate in an initial series of 10 cases treated with interlaminar fusion in association of other fusion techniques in the thoracic spine with good results. Objective: Intralaminar screws have been shown to be a biomechanical salvage technique in the thoracic spine, especially in long cervicothoracic, thoracic and thoracolumbar fixation. The goals of this article are to demonstrate our initial experience and the range of indications for thoracic crossed intralaminar screws. Methods: In this article we describe our initial series performed at S&#227o Teot&#243nio Hospital in Viseu, Portugal, and our results, and also provide a comprehensive review of the recent literature in the use of intralaminar crossed fixation.

Single-Position Oblique Lumbar Interbody Fusion and Percutaneous Pedicle Screw Fixation under O-Arm Navigation: A Retrospective Comparative Study

The insertion of pedicle screws in the lateral position without a position change has been reported. We completed a retrospective comparison of the radiologic and clinical outcomes of 36 patients who underwent either single-position oblique lateral lumbar interbody fusion (SP-OLIF) using the O-arm (36 cases) or conventional OLIF (C-OLIF) using the C-arm (20 cases) for L2-5 single-level lumbar degenerative diseases. Radiological parameters were analyzed, including screw accuracy (Gertzbein-Robbins classification system; GRS), segmental instability, and fusion status. Screw misplacement was defined as a discrepancy of ≥2 mm. Clinical outcomes, including visual analog scale, Oswestry Disability Index (ODI), 36-Item Short Form Health Survey (SF-36), and postoperative complications, were assessed. The spinal fusion rate was not different between the SP-OLIF and C-OLIF groups one year after surgery (p = 0.536). The ODI score was lower (p = 0.015) in the SP-OLIF than the C-OLIF group. Physical (p = 0.000) and mental component summaries (p = 0.000) of the SF-36 were significantly higher in the SP-OLIF group. Overall complication rates, including revision, surgical site infection, ipsilateral weakness, and radicular pain/numbness, were not significantly different. SP-OLIF using the O-arm procedure is feasible, with acceptable accuracy, fusion rate, and complication rate. This may be an alternative to conventional two-stage operations.

Low-cost 3D Modeling Software for Generating Patient-specific Drill Guide Templates for Cervical Pedicle Screw Insertion: An In Vitro Study

Background. Instrumented posterior cervical spine surgery (IPCSS) can be conducted using screws inserted through the pedicles of the vertebra. A safe IPCSS method uses 3D-printing to produce templates that will serve as drill guides for screw placement.Objectives. This study describes the generation of 3D-printed drill guides using low-cost general purpose 3D modeling software and the comparison of screw insertion accuracy scores against the traditional landmark method and guides created using commercial grade software.Methods. Twenty-five (25) subaxial pedicles of five cadaveric spines were selected and scanned using computedtomography (CT). A digital reconstruction of the five cadaveric spines were created based on the CT DICOM data. A low-cost 3D modeling software, Rhinoceros 3D, was utilized for trajectory planning and generation of a patientspecific drill template using the digital reconstruction. The templates were then fabricated in ABS plastic using a fused deposition modeling (FDM) 3D printer. Insertion of cervical pedicle screws on the cadaveric spines was done by an orthopedic resident using the 3D printed guides. Postoperative CT scans were obtained, and placement accuracy of the screws were scored by two assessors utilizing a four-point rating system. Screws in correct placement were scored Grade 0 while misplaced screws with neurovascular damage were given a score of Grade 3.Results. Accuracy scores for the 3D-printed drill guides were 52% for assessor 1 and 44% for assessor 2. Forassessor 1, screw placement in C3, C6, and C7 received the highest scores. For assessor 2, the highest scores were achieved in C3 and C7. The hybrid method of Bundoc et al. achieved scores of 94% while 3D printed guides utilizing commercial software like Materialise Mimics, Geomagic Freeform, or UG Imageware achieved scores of 80-100%. The traditional landmark method had scores ranging from 12% to 94% depending on the skill of the surgeon.Conclusion. Commercial medical 3D image-based engineering software has high acquisition costs that might be beyond the reach of most institutions. A sub-$1000 general purpose 3D modeling software can be used to create drill templates. Several factors were identified in the design and fabrication of the template that can be addressed to increase accuracy. Trajectory planning can also be improved by automating the process. The researchers recommend further studies in these areas specially in the context of developing 3D printing as a support service for surgical operations in the Philippines.

Reduction in Radiation Exposure in Minimally Invasive Pedicle Screw Placement Using a Tubular Retractor: A Pilot Study

Percutaneous pedicle screw (PPS) placement is a minimally invasive spinal procedure that has been rapidly adopted over the last decade. However, PPS placement has elicited fear of increased radiation exposure from some surgeons, medical staff, and patients. This is because PPS placement is performed using a K-wire, and the operator must perform K-wire insertion into the pedicle under fluoroscopy. In order to prevent erroneous insertion, there are many occasions when direct insertion is required during radiation exposure, and the amount of radiation exposure to hands and fingers in particular increases. Although these problems are being addressed by navigation systems, these systems are still expensive and not widely available. Attempts have been made to address this situation using instrumentation commonly used in spinal surgery. First, it was considered to visualize anatomical bone markers using a tubular retractor and a microscope. In addition, the use of a self-drilling pin was adopted to locate the pedicle in a narrower field of view. Based on these considerations, a minimally invasive and highly accurate pedicle screw placement technique was developed while avoiding direct radiation exposure. This study evaluated radiation exposure and accuracy of pedicle screw placement using this new procedure in one-level, minimally invasive, transforaminal lumbar interbody fusion (MIS-TLIF). Data were collected retrospectively to review pedicle screw placement in single-level MIS TLIFs using a tubular retractor under a microscope. The total fluoroscopy time, radiation dose, and screw placement accuracy were reviewed. Extension of operating time was also evaluated. Twenty-four patients underwent single-level MIS TLIFs, with placement of 96 pedicle screws. There were 15 females and 9 males, with an average age of 64.8 years and a mean body mass index of 25.5 kg/m2. The mean operating time was 201.8 min. The mean fluoroscopic time was 26.8 s. The mean radiation dose of the area dose product was 0.0706 mGy∗m2. The mean radiation dose of air kerma was 6.0 mGy. The mean radiation dose of the entrance skin dose was 11.31 mGy. Postoperative computed tomography scans demonstrated 93 pedicle screws confined to the pedicle (97%) and three pedicle screw breaches (3.2%; two lateral, one medial). A patient with screw deviation of the medial pedicle wall developed right-foot numbness necessitating reoperation. There were no complications after reoperation. The average added time with this combined procedure was 39 min (range 16-69 min) per patient. This novel pedicle screw insertion technique compares favorably with other reports in terms of radiation exposure reduction and accuracy and is also useful from the viewpoint of avoiding direct radiation exposure to hands and fingers. It is economical because it uses existing spinal surgical instrumentation.

Initial single surgeon evaluation comparing C-arm fluoroscopy with the Cirq robotic assistance device for instrumentation of the thoracolumbar spine

ObjectiveTo compare our experience with pedicle screw insertion of the thoracolumbar spine utilizing the Cirq robot assistance device compared with traditional paradigm using fluoroscopy.MethodsWe prospectively collected data of patients undergoing pedicle screw instrumentation in the thoracolumbar spine performed by a single surgeon at three different centers. One center took delivery of the Cirq robotic assistance device. Remaining two centers used C-arm fluoroscopy. Demographic information, diagnosis, total OR time, intraoperative complications, unexpected return to the operating room, and hospital readmissions within 90 days was compared between the two cohorts.ResultsA total of 166 screws were placed during the study period. Forty percent were placed using the Cirq. Two thirds the patients had traumatic diagnoses with remaining degenerative spine disease. There were no misplaced pedicle screws in either group. While total OR time was longer in the Cirq cohort by 123 min (p = 0.04), actual procedural time was not statistically different (p = 0.11). Nonetheless there were also more hospital readmissions in the Cirq cohort compared with the C arm group (p = 0.04).ConclusionsThoracolumbar screws inserted using C-arm fluoroscopy utilize less total operating room time with similar accuracy compared with the Cirq robotic assistance device. Further studies are warranted.

Camera-based navigation in the hybrid operating room

Camera-based navigation in the hybrid operating room represents apossibility for precise, low-complication and efficient pedicle screw insertion in spinal surgery. In addition to increasing patient safety, the use of camera-based navigation as an orientation aid for the surgeon reduces radiation exposure. Camera-based navigation focuses on the surgeon's anatomical knowledge of landmarks, preoperative image acquisition, and subsequent information integration by the navigation software. The information provided from volume tomography (cone beam computed tomography, CBCT) and surface referencing through the video input from four optical cameras and the associated surface markers is collected, processed, optimized and customized by the software used. The result is the creation of atrajectory that allows the surgeon to analyze and evaluate complex anatomical structures more easily and facilitates the performance of the planned procedure. Minimally invasive insertion of pedicle screws using surface-reference navigation (augmented reality surgical navigation; ARSN) provides comparable accuracy to conventional fluoroscopic insertion of pedicle screws while reducing radiation by eliminating the need for postoperative computed tomographic imaging.

Canadian Spine Society

# Abstract 57. Radiographic reporting in adolescent idiopathic scoliosis: Is there a discrepancy comparing radiologists’ reports and surgeons’ assessments? {#article-title-2} Cobb angle measurement is the standard method for quantification of scoliosis in adolescent idiopathic scoliosis (AIS),

Comparison of the Accuracy of Pedicle Screw Placement Using a Fluoroscopy-Assisted Free-Hand Technique with Robotic-Assisted Navigation Using an O-Arm or 3D C-Arm in Scoliosis Surgery.

Retrospective. To report and compare the application of robotic-assisted navigation with an O-arm or three-dimensional (3D) C-arm-assisted pedicle screw insertion in scoliosis surgery, and compare with free-hand technique. One hundred and forty-four scoliosis patients were included in this study. Ninety-two patients underwent robotic-assisted pedicle screw insertion (Group A), and 52 patients underwent freehand fluoroscopy-guided pedicle screw insertion (Group B). Group A was further divided into Subgroup AI (n = 48; robotic-assisted navigation with an O-arm) and Subgroup AII (n = 44; robotic-assisted navigation with a 3D C-arm). The evaluated clinical outcomes were operation time, blood loss, radiation exposure, postoperative hospital stay, and postoperative complications. The clinical outcomes, coronal and sagittal scoliosis parameters and the accuracy of the pedicle screw placement were assessed. There were no significant differences in blood loss and postoperative hospital stay between Groups A and B (P = .406, P = .138, respectively). Radiation exposure for patients in Group A (Subgroups AI or AII) was higher than that in Group B (P < .005), and Subgroup AI had higher patient radiation exposure compared with Subgroup AII (P < .005). The operation time in Subgroup AII was significantly longer than that in Subgroup AI and Group B (P = .016, P = .032, respectively). The proportion of clinically acceptable screws was higher in Group A (Subgroups AI or AII) compared with Group B (P < .005). Robotic-assisted navigation with an O-arm or 3D C-arm effectively increased the accuracy and safety in scoliosis surgery. Compared with robotic-assisted navigation with a 3D C-arm, robotic-assisted navigation with an O-arm was more efficient intraoperatively.

Development and Clinical Trial of a New Orthopedic Surgical Robot for Positioning and Navigation.

Robot-assisted orthopedic surgery has great application prospects, and the accuracy of the robot is the key to its overall performance. The aim of this study was to develop a new orthopedic surgical robot to assist in spinal surgeries and to compare its feasibility and accuracy with the existing orthopedic robot. A new type of high-precision orthopedic surgical robot (Tuoshou) was developed. A multicenter, randomized controlled trial was carried out to compare the Tuoshou with the TiRobot (TINAVI Medical Technologies Co., Ltd., Beijing) to evaluate the accuracy and safety of their navigation and positioning. A total of 112 patients were randomized, and 108 patients completed the study. The position deviation of the Kirschner wire placement in the Tuoshou group was smaller than that in the TiRobot group (p = 0.014). The Tuoshou group was better than the TiRobot group in terms of the pedicle screw insertion accuracy (p = 0.016) and entry point deviation (p < 0.001). No differences were observed in endpoint deviation (p = 0.170), axial deviation (p = 0.170), sagittal deviation (p = 0.324), and spatial deviation (p = 0.299). There was no difference in security indicators. The new orthopedic surgical robot was highly accurate and optimized for clinical practice, making it suitable for clinical application.

The pedicle width predicts an accurate screw insertion

Introduction. Correlation between pedicle screw malposition and small values of pedicle morphometric parameters has been confirmed in numerous studies. Definition of critical pedicle size for screw insertion is an actual problem for pediatric spinal surgery.Material and methods. 29 patients, aged 3-17, with congenital or acquired spinal deformities were included in the study. All the patients had posterior surgery with pedicle screw implantation. All the screws were inserted by free hand technique. On preoperative CT, external pedicle width, internal pedicle width, and spongiosa proportion were measured. On postoperative CT, pedicle screw accuracy was evaluated. The binomial logistic regression was used to define dependence of pedicle screw accuracy on pedicle morphometric parameter values. ROC-curves were graphed, and AUC were calculated.Results. 233 pedicle screws were implanted to 29 patients by free hand technique. On postoperative CT, 191 (82%) screws were confirmed to be accurately inserted. The logistic model confirmed significance of all the examined morphometric parameters (p0.001). The external pedicle width possessed the maximal predictive value. Statistical indices for the prognostic model (sensitivity, specificity, and accuracy) were calculated for pedicle width 3.5; 6.0; 7.5 mm.In the cut-off value of external pedicle width 3.5 mm, probability of accurate screw insertion is about 50%; this technique has been highly sensitive and maximally accurate. This morphometric feature is a technical limit of free hand pedicle screw insertion. Recommendations for selecting an implantation technique in different pedicle width are proposed.Conclusion. The external pedicle width 3.5 mm is a critical one for pedicle screw insertion by the free hand technique.

Effect of sagittal screw angle and distance of screw apex to superior endplate on adjacent segment disease after posterolateral lumbar fusion: a retrospective study

BackgroundNumerous complications of lumbar fusion surgery have been reported, with adjacent segment disease (ASD) being one of the most important. Few studies describe the effect of sagittal, horizontal screw angles and distance of pedicle screw apex to superior endplate on the incidence of ASD in lumbar spine. The purpose of this retrospective study is to evaluate the hypothesis that unsatisfactory pedicle screw insertion positions would increase the likelihood of ASD.MethodsOutpatients with lumbar spinal stenosis underwent posterolateral lumbar fusion at L4-S1 with a least 2-year follow-up were studied. ASD at L3–L4 was defined as a condition in which intervertebral disk narrowing, posterior vertebral opening, and vertebral slippage progress at the last follow-up in comparison with the postoperative. Independent t test was performed to compare data between two groups; Spearman analysis was performed to analyze the relationship between two continuous variables. Multivariate binary logistic models were performed to identify the independent risk factors of ASD. The receiver operating characteristic (ROC) curve was performed to measure model discrimination and Hosmer–Lemeshow (H–L) test was used to measure calibration. ROC curve evaluated the discrimination ability of sagittal screw angle and distance in predicting incidence of ASD.ResultsPatients in ASD group exhibit higher incidence of osteoporosis, higher Visual analogue scale (VAS), Oswestry disability index (ODI), bigger sagittal screw angle, shorter distance of pedicle screw apex to superior endplate than those in non-ASD group (p < 0.05). VAS, ODI at the last follow-up were positively correlated with Pfirrmann grade of L3–4 disk and sagittal screw angle, while negatively correlated with distance of screw apex to superior endplate (p < 0.05). Multivariate binary logistic model indicated that follow-up time (odds ratio [OR] 1.637, 95% confidence interval [CI] 1.186–2.260), distance of screw apex to superior endplate (OR 0.150, 95% CI 0.067–0.336), sagittal screw angle (OR 2.404, 95% CI 1.608–3.594) were statistically significant. The models showed great discrimination and calibration. The area under the curve of ASD identified by sagittal angle and distance was 0.895 and the cut-off values were 5.500° and 6.250 mm, respectively.ConclusionSagittal screw angle and distance of screw apex to superior endplate were significantly associated with the risk of ASD.

Preliminary results of biportal endoscopic lumbar interbody fusion, decompression and pedicle screw insertion assisted with endoscopic technique for lumbar spinal stenosis combined with spondylolisthesis or instability

Objectives: To evaluate the preliminary clinical outcomes of biportal endoscopic lumbar interbody fusion (BE-LIF), decompression and pedicle screw insertion assisted with endoscopic technique for lumbar spinal stenosis combined with spondylolisthesis or instability. Methods: The data of 9 patients with single-level lumbar spinal stenosis who underwent BE-LIF, decompression and pedicle screw insertion assisted with biportal endoscopy in Xinjiang Production and Construction Corps Hospital from March 1st 2022 to April 30th 2022 were analyzed retrospectively. The visual analogue scales (VAS) for pain in back and legs, and the Oswestry disability index (ODI) of all the patients were collected before operation, on the third day after operation and at the last follow-up. Moreover, the operation time, intra-operation blood loss, radiation shots for pedicle screw insertion, post-operation drainage and ambulation time were recorded. The screw position was checked with CT after the operation. Results: All the patients were female with a mean age of (70.3±8.4) years (ranged 56-84 years); the patients were followed-up for 12-16 weeks. All 9 patients had good clinical results. The VAS scores for back pain on the third day after operation and at the last follow-up were both significantly lower than that preoperatively[(2.9±0.6), (1.8±0.4) vs (6.4±1.1) points, both P<0.05]. The VAS scores for leg pain on the third day after operation and at the last follow-up were both significantly lower than that preoperatively[(1.9±0.3), (1.4±0.5) vs (7.3±1.6) points, P<0.05]. The ODI scores at last follow-up was significantly lower than that before the operation ((24.0%±6.5% vs 55.7%±12.8%, P<0.05). The intra-operative blood loss was (177±103) ml, the drainage amounts post-operation was (122±56) ml, the operation time was (207.8±32.7)min, the ambulation time was (2.3±0.5) days. The total radiation shots for pedicle screw insertion were 20-42 times, the average radiation shots per screw was (6.9±1.5) times. No severe complications or adverse events occurred. No nerve root injury or dural tear occurred in the operation, and no revision surgery needed. Conclusions: The pedicle screw insertion assisted with biportal endoscopic technique can decrease the radiation exposure with good feasibility and safety during the BE-LIF. The BE-LIF combined with the pedicle screw insertion assisted with biportal endoscopy is an effective and safe surgery for lumbar spinal stenosis with good early results.

Accuracy of Patient-Specific 3D-Printed Guides for Pedicle Screw Insertion in Spine Revision Surgery: Results of a Retrospective Study.

This retrospective study was performed to evaluate the safety and efficacy of patient-specific 3D-printed guides (MySpine® Medacta, Switzerland) for pedicle screw placement in spine revision surgery. Overview of the Literature: Placement of pedicle screws in spine revision surgery can be challenging due to the loss of anatomical landmarks and the presence of a fusion mass. Nevertheless, only a few papers have dealt with this topic. Several strategies, ranging from the freehand technique to navigation and robotics, have been developed. However, they all have drawbacks, including the amount of radiation given to the patient, the complexity of the equipment with a consequent increase in surgical time or costs, and the need of extended surgical training. Therefore, no consensus has yet been found regarding the best choice for dealing with revisions. Recently, patient-specific 3D-printed guides for screw placement have been introduced. Prospective studies have demonstrated their superiority over the freehand technique in primary deformity cases, but there are no studies on their results in revisions. Patients who underwent revision surgery for adult spinal deformities with 3D-printed guides were included. Radiographical parameters and complications were collected. The accuracy of each screw was measured on postoperative CT scan and graded according to the Gertzbein-Robbins and Zdichavsky classifications. Nine patients (mean age 34.6 years, mean follow-up 34.4 months) were included for a total of 203 screws. The relative accuracy (Gertzbein-Robbins A+B) was 94.7%. Of the 11 misplaced screws, 8 (72.7%) were lateral, 3 (27.3%) were anterior and 0 were medial. No perioperative complications were recorded, and no screw needed revision. The present technology appears to be effective and safe for pedicle screw placement in spine revision surgery and does not require the costs, training and radiation exposure associated with navigation and robotics.

A Novel Point Set Registration-Based Hand-Eye Calibration Method for Robot-Assisted Surgery.

Pedicle screw insertion with robot assistance dramatically improves surgical accuracy and safety when compared with manual implantation. In developing such a system, hand-eye calibration is an essential component that aims to determine the transformation between a position tracking and robot-arm systems. In this paper, we propose an effective hand-eye calibration method, namely registration-based hand-eye calibration (RHC), which estimates the calibration transformation via point set registration without the need to solve the AX=XB equation. Our hand-eye calibration method consists of tool-tip pivot calibrations in two-coordinate systems, in addition to paired-point matching, where the point pairs are generated via the steady movement of the robot arm in space. After calibration, our system allows for robot-assisted, image-guided pedicle screw insertion. Comprehensive experiments are conducted to verify the efficacy of the proposed hand-eye calibration method. A mean distance deviation of 0.70 mm and a mean angular deviation of 0.68° are achieved by our system when the proposed hand-eye calibration method is used. Further experiments on drilling trajectories are conducted on plastic vertebrae as well as pig vertebrae. A mean distance deviation of 1.01 mm and a mean angular deviation of 1.11° are observed when the drilled trajectories are compared with the planned trajectories on the pig vertebrae.

A systematic review on the cost‐effectiveness of the computer‐assisted orthopedic system

AbstractComputer‐assisted orthopedic system (CAOS) is rapidly gaining popularity in the field of precision medicine. However, the cost‐effectiveness of CAOS has not been well clarified. We performed this review to summarize and assess the cost‐effectiveness analyses (CEAs) with regard to CAOS. Publications on CEA in CAOS have been searched in PubMed and CEA Registry up to May 31, 2022. The Quality of Health Economic Studies (QHES) instrument was used to estimate the quality of studies. Relationships between qualities and potential factors were also examined. There were 15 eligible studies in the present review. Twelve studies evaluated CAOS joint arthroplasties and found that CAOS joint arthroplasties were cost‐effective compared to manual methods. Three studies focused on spinal surgery, two of which analyzed the cost‐effectiveness of CAOS for patients after spinal fusion, with conflicting results. One study demonstrated that CAOS was cost‐effective in spinal pedicle screw insertion. The mean QHES score of CEAs included was 86.1. The potential factors had no significant relationship with the quality of studies. Based on available studies, our review reflected that CAOS was cost‐effective in the field of joint arthroplasty. While in spinal surgery, the answer was unclear. Current CEAs represent high qualities, and more CEAs are required in the different disciplines of orthopedics where CAOS is employed.

New classification of S1 pedicle morphometry impacting pedicle screw insertion technique

&lt;p&gt;&lt;strong&gt;Background:&lt;/strong&gt; The conventional entry point for the S1 pedicle screw insertion has been described as ‘at the base of and lateral to the superior S1 superior facet’. However, many orthopaedic surgeons complain that this technique is extremely demanding and is faced with many challenges in execution. Therefore, alternative entry points and modifications of existing techniques are explored for a greater convenience.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods&lt;/strong&gt;: We conducted a survey amongst 136 spine surgeons on the technical difficulties faced during insertion of the S1 pedicle screw. We also classified the S1 pedicles based by measuring their geometric parameters on 100 random computed tomography (CT) images.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results&lt;/strong&gt;: The S1 pedicle entry technique was considered to be the most difficult and challenging by the orthopaedic surgeons in our survey due to an inadequate medial angulation due to paraspinal muscle mass tension and an overhanging iliac crest. This could be explained by the hourglass shaped pedicle (type 3) with a desired medial angle more 50 degrees (type III) observed as the most common S1 pedicle in the study population. To overcome this limitation, most of them preferred a tri-corticate approach.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;: A more lateral entry point and a longer screw might be considered as solutions for a better and safer S1 pedicle entry. Also, the use of pre-operative CT can be considered to visualize the type of S1 pedicle and hence, decide on the most appropriate technique of screw insertion.&lt;/p&gt;&lt;p&gt;&lt;strong&gt; &lt;/strong&gt;&lt;/p&gt;

3D printing in spine care: A review of current applications

3D printing (3DP) has been brought to medical use since the early part of this century- but it has been widely researched on and publicized only in the last few years. Amongst patients with spinal disorders, 3DP has been utilized in various facets of patient care. These include pre-operative aspects - such as patient education, resident training, pre-operative planning and simulations, intra-operative assistance in the form of customized jigs for pedicle screw insertion, patient specific interbody cages and vertebral body substitutes in complex malignancies and spinal infections. It has also been utilized in deformity surgeries and has opened new avenues in minimally invasive spine care. Guidelines have now been drafted by various organizations including the FDA with a prime focus on quality control measures applicable to this new technology. There has been a recent surge in publications supporting the use of 3DP in spinal disorders, reporting an improvement in various aspects of patient care. As the technology spreads out its wings further, more innovations and applications are expected to unfold in the coming years. Considering the rapid advances that 3DP has made, having a basic understanding of this technology is imperative for all spine surgeons. Despite promising preliminary results, there still exist a few pitfalls of the technology which have hindered the universal application of 3DP. Most importantly, there is a dearth of data related to long term outcomes supporting its clinical use. The prohibitive cost of 3D models, the specialized manpower it necessitates and the need for specific instrumentation are major deterrents to widespread use of this technology, particularly in small-scale healthcare setups. With further advancements in technology, the goal must be to make it more accurate and affordable to hospitals and patients so that the benefits of the technology can reach a wider patient population.

Correction of pediatric cervical kyphosis with standalone posterior approach-a single-center experience of seven cases.

To study clinical and radiological outcomes of pediatric cervical kyphosis correction with a standaloneposterior cervical approach. Cervical spine kyphotic deformity in pediatric age group is a distinct entity and themanagement is challenging. Pediatric cervical kyphosis is less often encountered, and literature is sparse with onlyfew case series. Management algorithms are devised keeping the flexibility of the deformity at the core of decisionmaking. Circumferential fusion is mostly recommended for non-flexible (rigid) kyphosis. Authors present a single center retrospective analysis of cases of pediatric cervical kyphosis managed bya standalone posterior approach. Pre- and post-operative clinical and radiological parameters were recorded andanalyzed. Changes in neurological status, kyphosis correction and bony fusion were assessed. Surgical andimplant related complications were noted. Seven cases (6 male, 1 female) were included. Mean age was 13.9±2.9 years, ranging from 8-17 years.Etiology was traumatic in 2 cases, developmental in 2, and syndromic, Hirayama disease and post-laminectomy in1 case each. Mean kyphosis correction was 36.80±19.30 (87%±21%) with a mean pre-operative kyphosis angle of37.80±15.30 and mean immediate post-operative kyphosis angle of 3.70±8.70. Mean hospital stay duration was10±6 days. Median follow-up duration was 36 months. Myelopathy improved in 5 cases at last follow-up. Six casesdemonstrated bony fusion at a mean follow-up of 8.4±1.5 months. Significant immediate correction in pediatric cervical kyphosis may be achieved with a standaloneposterior approach with proper planning and technique in selected cases. Inserting pedicle screws at strategiclocations of implant construct offer better corrections and pull-out strength and maintain long-term stability resultingin higher arthrodesis rates. Larger studies with longer follow up are needed to further ascertain the role ofstandalone posterior cervical approaches in pediatric cervical kyphosis.

Comparison of Perpendicular to the Coronal Plane versus Medial Inclination for C2 Pedicle Screw Insertion Assisted by 3D Printed Navigation Template.

C2 pedicle screw insertion is very important in posterior upper cervical surgery. The traditional screw placement technique requires us to consider both medial inclination and cephalad angle, it is difficult to operate intraoperatively. This paper is to explore a novel method of C2 pedicle screw placement compared with traditional C2 pedicle screw. A total of 44 patients diagnosed with atlantoaxial fracture or instability from May 2018 to November 2020 were involved in this retrospective study, and they were divided into C2-PPS group (perpendicular to the coronal plane C2 screw, 24 patients) and C2-TPS group (traditional C2 pedicle screw, 20 patients). The diameter of the maximum tangential circle, distance between geometric center and median sagittal plane and screw length of PPS and TPS were measured based on the 3D model of C2, respectively. Then the 3D printed navigation templated were designed and manufactured by 3D printing to assisted the PPS and TPS placement, respectively. The surgical time and radiation exposure times during operation were recorded; the post-operative grading criteria, deviation of screw entry point and deviation of screw angle of two groups were evaluated, respectively. A total of 48 screws were inserted in the C2-PPS group, and 40 screws were inserted in the C2-TPS group. There were 46 screws with grade 0 (95.8%) in the PPS group and 31 screws with grade 0 (77.5%) in the TPS group, (P=0.03). The radiation exposure times in the C2-PPS group and C2-TPS group were 4.7 ± 1.5 and 7.8 ± 3.8, respectively, (P=0.045). The deviations of screw entry point in the C2-PPS group and C2-TPS group were 1.2 ± 0.8 mm and 3.2 ± 1.3 mm, respectively; the deviations of screw angle in the C2-PPS group and C2-TPS group were 2.1 ± 1.6° and 4.8 ± 2.0°, respectively, (P=0.000). The diameters of the maximum tangential circle in the C2-PPS group and C2-TPS group were 5.5 ± 1.0 mm and 5.3 ± 0.9 mm, respectively. The distances between the geometric center and median sagittal plane in the C2-PPS group and C2-TPS group were 15.4 ± 2.3 mm and 18.0 ± 3.3 mm, respectively; The screw lengths in the C2-PPS group and C2-TPS group were 25.9 ± 3.2 mm and 27.6 ± 3.7 mm, respectively, (P=0.000). Eighty percent of C2-PPS corridor can accommodate a 3.5 mm diameter screw, and with an average screw length of 26 mm. Navigation templates assisted the C2-PPS placement is less surgical time, less radiation exposure times, more safe and more accurate than C2-TPS.