Total Number Of Screws Research Articles

Blood Loss Control in Patients with Idiopathic Scoliosis Undergoing Spinal Fusion: Prospective Evaluation of a Cohort.

Objective This study aimed to identify risk factors for increased perioperative bleeding in scoliosis surgery. Methods This is a prospective cohort study including 30 patients with idiopathic scoliosis undergoing posterior instrumentation using the pedicle screw system at a university hospital. Results Intraoperative blood losses totaled 798.6 ± 340 mL (24.8% of blood volume). Nine subjects presented massive blood loss. On average, hemoglobin dropped by 3.7 g/dL, and each patient received 1.4 blood bags. Postoperative blood loss was 693.4 ± 331.1 mL, and the total number of days using a drain was 2.7 ± 0.7. Intraoperatively, the following variables showed significant correlations ( p < 0.05) with increased bleeding: age, time from diagnosis to treatment, preoperative Cobb angle, amount of curve correction, number of instrumented and fixated levels, total number of screws, and the number of transfused bags. Postoperatively, the following variables had significant correlations ( p < 0.05): age, preoperative Cobb angle, length of hospital stay, number of blood bags transfused, and number of levels fixated with screws. Conclusion The variables most contributing to blood loss were age, preoperative Cobb angle, number of blood bags transfused, and number of levels fixated with a screw. Therefore, patients may benefit from surgical treatment while younger and presenting a lower Cobb angle, consequently requiring a lower degree of curve correction and lower-density implants.

Use of a high-speed drill in robotics coupled with navigation for pediatric spine surgery.

With the increasing number of surgeries for pediatric spinal deformities, the aim has been to reduce the associated complications, such as those caused by screw malposition. This case series is an intra-operative experience with a newnavigated high-speed revolution drill (Mazor Midas, Medtronic, Minneapolis, MN) for pediatric spinal deformity to assess accuracy and workflow. 88 patients, ranging from 2 to 29years of age, were included who underwent posterior spinal fusion with the navigated high-speed drill. Diagnoses, Cobb angles, imaging, surgical time, complications, and total number of screws placed are described. Screw positioning was evaluated using fluoroscopy, plain radiography, and CT. Mean age was 15.4years old. Diagnoses included 47 adolescent idiopathic scoliosis, 15 neuromuscular scoliosis, 8 spondylolisthesis, 4 congenital scoliosis, and 14 other. The mean Cobb angulation for scoliosis patients was 64° and the mean number of levels fusedwas 10. 81 patients had registration via intraoperative 3-D imaging and 7 had pre-operative CT scan to fluoroscopy registration. There were a total of 1559 screwswith 925 placed robotically. 927 drill paths weredrilled with the Mazor Midas. 926 out of 927 drill paths were accurate. The mean surgical time was 304min with the mean robotic time being 46min. This is the first intra-operative report to our knowledge documenting the experience with the Mazor Midas drill in pediatric spinal deformity showing decreased skiving potential, decreased torque when drilling, and lastly increased accuracy. Level of evidence: level III.

Accuracy and safety of percutaneous pedicle screw placement using the K-wireless minimally invasive spine percutaneous pedicle screw system in Japan: A randomized active controlled study

BackgroundMinimally invasive lumbar fusion has recently become a widely used technique worldwide. This randomized active controlled study was conducted to demonstrate the non-inferiority of the K-wireless Minimally Invasive Spine (MIS) Percutaneous Pedicle Screw (PPS) system compared with use of the six pedicle screw systems currently used in our practices with respect to the accuracy of pedicle screw placement.Also to compare the screw-insertion time and number of fluoroscopic observations during screw insertion between the groups. MethodsA total of 80 patients with degenerative spinal diseases or vertebral fractures were assigned, including 41 patients in the K-wireless MIS PPS system group (K-wireless group) and 39 in the control group (K-wire group).The accuracy of the screw insertion, screw-insertion time, number of fluoroscopic observations during screw insertion, and the incidence of adverse events were compared between the K-wireless group and the K-wire group. The accuracy rate was calculated as the number of screws with no breach divided by the total number of screws. ResultsThe accuracy rates of screw insertion were 85.7% and 75.0% in the K-wireless and K-wire groups, respectively, with an intergroup difference of 10.7% (95% confidence interval: 2.3–19.1%). The K-wireless group demonstrated non-inferiority compared with the K-wire group. The mean screw-insertion time was significantly shorter in the K-wireless group (2.62 and 2.97 min in the K-wireless and K-wire groups, respectively; P=0.005). There were also significantly fewer fluoroscopies in the K-wireless group (10.7 and 17.4 in the K-wireless and K-wire groups, respectively; P<0.001). There were no device-related or study treatment-related adverse events in either group. ConclusionsThe accuracy of pedicle screw insertion using the K-wireless MIS PPS system was not inferior to that of existing products. In terms of safety, no product-related or treatment-related adverse events were identified in this study and no new safety concerns were noted.

Efficiency of Long Lateral Mass Screws.

Introduction: Lateral mass screws (LMS) have been widely used for the posterior fusion of the cervical spine. Even though LMS are safe, the screws are short and postoperative fixation is uncertain. Therefore, we measured and reported a technique using long lateral mass screws (LLMS), a new method of screw insertion, using a Zed spine from LEXI (Tokyo, Japan). Materials and Methods: In this study, we evaluated the outcomes of 35 patients who underwent surgery using LLMS at our hospital from 2019 to 2021. Operative time, blood loss, complications, inserted screw length, screw length based on gender differences, and screw deviation rate were evaluated. The Mann–Whitney U test was used to determine the gender differences in screw length. Screw deviation was evaluated by postoperative CT and a Zed spine to determine the screw insertion angle. Results: The mean operative time was 185 ± 51 min (120–327 min), and the mean blood loss was 236 ± 316 g (10–1720 g). The total number of screws was 183. The screw length was 22.2 (16–28) mm for males and 20.8 (16–28) mm for females, with an average length of 21 ± 2.7 mm. No gender differences were observed in terms of screw length (p > 0.01 NS). The number of deviated screws above G3 was one in the third cervical vertebra, three in the fourth cervical vertebra, one in the fifth cervical vertebra, and one in the sixth cervical vertebra. The number of deviated screws was 6 out of 183, and the deviation rate was 3.2%. Conclusions: In this study, the LLMS deviation rate was 3.2%, and strong fixation was possible without any complications. We measured the screw length and screw deviation rate in cases in which LLMS were actually inserted.

The in vivo impact of computer navigation on screw number and length in reverse total shoulder arthroplasty

Little information exists regarding the benefit of computer navigation in shoulder arthroplasty in the clinical setting. This study aims to quantify how computer navigation affects the number and length of screws used during in vivo reverse total shoulder arthroplasty (RSA) placement. A retrospective review of a research database was performed from 1/1/2015 to 12/31/2019 to identify patients who underwent primary RSA before and after the use of computer navigation. One-hundred consecutive RSAs were selected from the computer navigation implantation date; then, 100 consecutive sex-matched RSAs were chosen prior to navigation implantation in reverse chronological order. Baseplate augments were chosen based on surgeon discretion, with the goal of restoring version to within 10 degrees of neutral and inclination to neutral or slightly inferior with removal of the smallest amount of subchondral bone possible. Screws were placed with the goal of at least 3 screws with good purchase and added as needed, with up to 5 screws utilized. We compared demographic factors, comorbidities, preoperative diagnosis, number of screws, screw length, number of wasted screws, and number of cases with bone graft used behind the baseplate between the 2 groups. Chi-squared test was used for bivariate analysis and student t-test was used for continuous variables. A total of 200 RSAs were included, with 100 primary RSAs (mean age, 69.3 years) performed prior to computer navigation compared to 100 primary RSAs (mean age, 69.7 years) performed using computer navigation. The total number of screws used in RSAs without computer navigation was 414 screws; the total used in the computer navigation cases was 344. RSAs placed with computer navigation used significantly fewer screws per case (3.4 vs. 4.1 screws; p<0.001) and had a significantly longer average screw length (35.0mm vs. 32.6mm; p<0.001). Three screws were implanted in 61% of computer navigation cases compared to 1% of cases without computer navigation (p<0.001). Screws 30mm in length or longer were more commonly used in patients undergoing RSA using computer navigation (84.6% vs. 73.7%; p<0.001). This study shows that computer navigation in RSA leads to longer and fewer glenoid baseplate screws being implanted. Computer navigation appears to assist with better screw placement, which may have similar clinical benefits of better glenoid fixation. Additionally, using fewer screws can save glenoid bone stock, avoid added glenoid stress risers, and decrease operative time.

Four Year Experience of Robot-Assisted Pedicle Screw Placement: An Australian Prospective Analysis

Abstract INTRODUCTION Robot-assisted surgery has emerged as an innovative and minimally-invasive technique, touted as superior to the traditional free-hand technique of pedicle screw fixation in spinal fusion surgery. Complications of misplaced pedicle screws include inadequate fixation and surgical failure requiring revision, neural injury, cerebrospinal fluid (CSF) leak, vascular injury, and facet joint trauma with sequela of adjacent segment disease. Literature reports an incidence of pedicle screw misplacement in up to 10% with free-hand technique. Robot-assisted surgery has reported superiority with increased accuracy of pedicle screw placement and reduced complication rates. This prospective multi-institutional single cohort analysis reports the outcomes in robot-assisted spinal fusion surgery in Melbourne, Australia over 4 yr. METHODS Data was prospectively collected from 2015 to 2019 from robot-assisted spinal surgeries performed by 2 surgeons across 2 institutions. Postoperative spinal computed tomography (CT) scan was compared to preoperative CT based planning to determine the accuracy of pedicle screw placement to 0.1 mm. Accurate pedicle screw placement was defined as within 2.0 mm from the target. Intraoperative radiation exposure time, operative time and length of hospital stay were also collected. RESULTS The total number of cases was 164 and the total number of screws placed was 744. Accurate pedicle screw placement was 98.65%. Average intraoperative radiation exposure time was 9.9 s. Average operative time for single-level surgery was 74 min. The average length of hospital stay was 2.4 d. CONCLUSION The authors conclude that robot-assisted pedicle screw placement is a safe and highly accurate adjunct to spinal surgery. While robot-assisted spinal surgery significantly improves patient outcomes with reduced patient morbidity and revision rates, it has limitations in primary capital expenditure, consumable costs and, in training and accreditation. It is the authors’ opinion that the robot-assisted spinal surgery technique requires nuanced patient selection and expertise in the traditional free-hand method is still essential in the event of technological failure.

The evaluation of long-term screw pull-out rates following posterior thoracolumbar fusion surgery with short and thin pedicle screws

Background. The aim of this study was to evaluate screw pull-out rates after fusion operations with short and thin pedicle screws.Methods. A total of 200 posterior lumbar and thoracolumbar fusion operations performed at our clinic with short and thin pedicle screws (5.5x35 mm) were retrospectively evaluated. The patients were assessed with computed tomography postoperatively on the day of surgery and at the 6th month. Single groove retraction of the transpedicular screw was evaluated as pull-out. The results were evaluated by the 'number of pull-out cases / total number of cases' and also the 'total number of pull-out screws / total number of screws used' ratios. Results. There were 112 (56%) female and 88 (44%) male patients with a mean age of 58 years. The total number of screws used in the 200 cases was 1188. There were 88 (7.4%) thoracic pedicle screws, 1056 (88.9%) lumbar pedicle screws and 44 (3.7%) sacral pedicle screws used. No pull-out was found in the control CTs taken postoperatively. Left side T11 and T12 pull-out was observed in one case and left L4 pull-out was observed in another case in the control CTs taken at the postoperative 6th month. Pull-out was observed in 2 (1%) of the 200 cases and 3 (0.25%) of the 1188 screws.Conclusions. All the short and thin pedicle screws used had passed the pedicle length and neurocentral junction. The use of a 5.5x35 mm screws in fusion operations is less invasive than using longer and thicker screws while the pull-out rates may be similar.

Structural Synthesis of Robot Manipulators by Using Screw with Variable Pitch

This paper focuses on the systematic type synthesis of parallel robot manipulators by using new structural formulas based on the screw theory. New structural formulas as a total number of screw in kinematic pairs , number of screws with variable pitch , total number of screws that represent the contact geometry of lower and higher joint elements (t), mobility equation for robot manipulators (M), dimension of the closed loop , motion of end effector of parallel manipulator , number degree of freedom of kinematic pairs , refers to find the kinematic structure of robot manipulators realizing a specified motion requirement. Twenty kinematic pairs with structural parameters are introduced. History of six structural formulas using for structural synthesis of parallel robot manipulators from space and different subspaces are presented as a table with equations, authors, years and some commentaries. The structural synthesis approach is based on the elementary notions of screw theory. Using the proposed of structural formulas approach, families of platform manipulators are constructed from a set of structural units. This paper is appropriate for engineers with interest in robotics, rovers, space docking parallel manipulators and screw theory.

Early discharge after posterior spinal fusion for adolescent idiopathic scoliosis is possible using an optimized postoperative pathway: a case-control study

Background: Patients with adolescent idiopathic scoliosis (AIS) are typically healthy and yet hospital stay after posterior spinal fusion (PSF) remains lengthy. Methods: A review of patients undergoing PSF for AIS by four pediatric orthopaedic surgeons was performed. Patients were divided based on their surgery occurring before or after the implementation of an accelerated discharge pathway (AD). Patients treated prior to the AD pathway were managed using a less standardized traditional (TD) pathway. Results: Four surgeons performed 99 PSF for AIS using the TD pathway and 81 PSF after implementation of the AD pathway. Length of stay was 20% shorter in patients managed under the AD pathway (3.29±0.61 days vs. 4.11±0.97 days, P&lt;0.0001) There was no difference in age, sex, preoperative main thoracic thoracolumbar curve magnitudes between groups. There was no difference in groups with regards to the use of osteotomies, number of levels fused, or total number of screws placed. Patients managed in the AD cohort had shorter surgical times (TD 4.55±0.9 hr vs. AD 4.19±1.11 hr, P=0.02) and lower estimated blood loss (TD 688±395 cc vs. AD 453±327 cc; P&lt;0.0001). Multivariate regression analysis revealed a 0.82 day reduction in length of stay when controlling for estimated blood loss and length of surgery. There was no statistical difference between groups with regards to any complications. Conclusions: The use of a coordinated discharge pathway helped to reduce length of stay in patients undergoing PSF for AIS without an increase in complications. This hospital stay of 3 days represents a dramatic decrease over previously published averages.

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

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

Intermaxillary Fixation Screw Morbidity in Treatment of Mandibular Fractures—A Retrospective Study

The aim of the present retrospective study was to investigate the morbidity of screws used for intermaxillary fixation (IMF) in the treatment of mandibular fractures. A review of the published data was also performed for a comparison of outcomes. Our hypothesis was that the use of screws for IMF of mandibular fractures would result in minimal morbidity. Patients treated for mandibular fractures from 2007 to 2013, using screws for IMF, using the international diagnosis code for mandibular fracture, DS026, were anonymously selected (Department of Oral and Maxillofacial Surgery, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark). The fracture type, radiographic findings, treatment modality, screw type and number, and root damage were recorded. For the outcome comparison, a review of the published data regarding iatrogenic dental root damage caused by screw fixation was performed in May2015. A total of 156 patients had undergone IMF with screws. The total number of screws was 793. The incidence of root lesions was 0.25% centrally and 0.88% peripherally. The incidence of screw loss was 0.13% and that of screw loosening was 1.89%. In the review, 737 related reports were identified in a search of PubMed and the Cochrane Library. Of these, 25 were considered suitable for inclusion. A lack of valid evidence resulted in a descriptive analysis, because a meta-analysis of the data was not possible. The results of the present retrospective study have shown that the use of screws is a valid choice for IMF in mandibular fracture treatment with minimal morbidity. The 793 screws used for IMF resulted in a negligible amount of central and peripheral tooth root trauma.

Thoracic Pedicle Screw Instrumentation

Retrospective review. The purpose of this study is to evaluate the learning curve and associated evolution in surgical technique with thoracic pedicle screw instrumentation in adolescent idiopathic scoliosis (AIS). Common treatment for AIS now includes posterior spinal fusion, using thoracic pedicle screws (TPS). It is critical to assess the efficacy, safety profile, and learning curve associated with this technique as its use becomes more widespread among inexperienced surgeons. Retrospective review of the senior author's first 96 TPS cases for Lenke Type I AIS curves. Multiple regression techniques were used to discern whether increasing case number (CN) was associated with improved perioperative and 2-year minimum radiographic and clinical outcomes. The 96 cases were divided into 4 equal quartiles of 24 cases/group (i.e., Q1-Q4) and compared using analysis of variance measures. A total of 1169 thoracic pedicle screws were placed in 96 patients. We found a significant correlation between CN and major curve correction at 2 years (P < 0.0001), inverse correlation between CN and length of stay (P = 0.02), and estimated blood loss (P = 0.03), but no differences in cell saver or complications. Univariate analysis revealed significant inverse correlations between increasing CN and transfusion rate (P = 0.02) and operative times (P = 0.0001). Total number of screws placed (Q1:9.4 vs. Q4:16.2, P < 0.0001) and number of screws/level (Q1:0.98 vs. Q4:1.64, P < 0.0001) increased linearly with increasing CN, whereas the average time for screw placement (Q1:24.2 vs. Q4:11.4 minutes, P < 0.0001) and ability to maintain T2-T12 kyphosis decreased (Q1:0.21 vs. Q4:-5.5 P = 0.02) with increasing CN. There is a significant learning curve associated with thoracic pedicle screw placement in AIS. We describe several technical steps that can be taken to increase the safety of screw placement at the beginning of the learning curve. Inexperienced surgeons should expect a gradual improvement over time in radiographic and clinical outcomes.

The Value of Washers in Cannulated Screw Fixation of Femoral Neck Fractures

Given the limited evidence to support the technical aspects of screw placement for treatment of femoral neck fractures, we conducted an observational study to evaluate demographic and radiographic variables associated with fixation failure. Eligible patients with femoral neck fractures were treated with multiple cannulated screws across three academic centers during a 6-year period. The following variables were evaluated for their predictive value for fixation failure: age, gender, fracture type, presence of comminution, total number of screws, the absence of a washer, the screw configuration, reduction quality, the distance of the most inferior screw to the inferior neck, and screw alignment. Variables were evaluated separately and in a multivariable regression model. Eighty patients were included in the study. The overall failure rate was 30%. We identified four variables associated with fixation failure. These included the lack of washers (odds ratio [OR], 11.2; p = 0.03), imperfect quality of reduction (OR, 9.7; p < 0.01), age greater than 75 years (OR, 5.1; p = 0.04), and displaced versus undisplaced fracture type (OR, 3.8; p < 0.01). These four variables accounted for 43% of the variability in fixation failure (R(2) = 0.43). All other variables including the distance of the most inferior screw to the inferior/medial neck were found to be not significant. This study confirms previous findings in the literature that increased age, a displaced fracture type, and poor reduction increase the risk of fixation failure. Contradictory to current belief, there was no significant association between the distance of the inferior screw to the inferior/medial femoral neck cortex and fixation failure. A novel finding of the present study is that the use of washers significantly decreases the risk of fixation failure.

Thoracic pedicle screw instrumentation using the "Funnel Technique": part 2. Clinical experience.

This study is a retrospective review of the clinical results of patients treated with thoracic pedicle screws using the "funnel technique." The objective is to report the clinical results of patients treated with thoracic pedicle screws using the funnel technique for screw placement. A total of 115 patients treated with the use of at least one thoracic pedicle screw were retrospectively identified. All patients were treated at a single medical center, under the senior author's supervision. Twenty-five different residents were responsible for placing 50-60% of these screws, and five different fellows and the senior author placed the remainder. The accuracy of screw placement and the complications related to the use of thoracic pedicle screws were analyzed by assessing intraoperative and postoperative charts and radiographs. There were 115 patients (age range 9-82 years) with the average follow-up period of 17 months. The total number of screws used was 348; the screw diameter ranged from 4.0 to 7.75 mm. There were no vascular or pulmonary complications. There was no iatrogenic neurologic injury, except for one patient who developed a transient anterior thigh numbness from intraoperative positioning. In fracture patients, 35% (10 of 28) had documented neurologic improvement postoperatively. There were no obviously misplaced pedicle screws on detailed review of intraoperative and postoperative radiographs. No screws had to be electively removed for complications related to misplacement. There were four broken screws, one broken rod, two loose screws, and three connector disengagements. Two patients had deep infections and four patients had pseudarthrosis requiring additional surgery. The clinical results proved that thoracic pedicle screws can be safely placed with the funnel technique.