scholarly journals The effect of cement augmentation on pedicle screw fixation under various load cases

2021 ◽  
Vol 10 (12) ◽  
pp. 797-806
Author(s):  
Yan Chevalier ◽  
Maiko Matsuura ◽  
Sven Krüger ◽  
Hannes Traxler ◽  
Christoph Fleege† ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Bone Quality ◽  
Pedicle Screws ◽  
Bending Stiffness ◽  
Cement Augmentation ◽  
Fixation Strength ◽  
Screw Design ◽  
Pull Out ◽  
Local Bone ◽  
Significant Difference

Aims Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. Methods Micro-finite element (µFE) models were created from micro-CT (μCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S4). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. Results Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R2 > 0.87) and FV (R2 > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient ( R) = -0.95). Conclusion This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict fixation strength in pull-out and that full analyses could show that cement augmentation around pedicle screws increased fixation stiffness in both pull-out and bending, especially for low-density bone. Cite this article: Bone Joint Res 2021;10(12):797–806.

Assessment of Cancellous Bone Strength in the Lumbar Spine Using a “Smart” Ball-Tip Probe

2010 ◽  
Author(s):  
Kate D. Liddle ◽  
Michael A. Tufaga ◽  
Glenn Diekmann ◽  
Jenni M. Buckley ◽  
Viva Tai ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Bone Quality ◽  
Local Variation ◽  
Clinical Problem ◽  
Mineral Density ◽  
Pull Out ◽  
Screw Augmentation ◽  
Local Bone ◽  
Highly Correlated ◽  
Operative Assessment

Failure of the pedicle screw at the screw-bone interface is a common clinical problem, particularly in the setting of osteoporosis, and poses reconstructive challenges for all orthopaedic surgeons. Pedicle screw failure through screw loosing and pull-out is highly correlated with bone mineral density (BMD) and local bone quality [1]. Pre-operative assessment of BMD via dual x-ray absorptiometry (DEXA) has been shown to help determine the need for screw augmentation. However, patients frequently present without pre-operative DEXA scans. Furthermore, DEXA scans provide a measure of general bone quality, but do not necessarily reflect segmental and local variation in the spine [2]. The ability to assess BMD on a per-vertebrae basis intra-operatively would assist with surgical decisions regarding screw sizing, placement and augmentation.

scholarly journals Cortical threaded pedicle screw improves fatigue strength in decreased bone quality

2020 ◽  
Author(s):  
Lukas Weiser ◽  
Kay Sellenschloh ◽  
Klaus Püschel ◽  
Michael M. Morlock ◽  
Lennart Viezens ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Pedicle Screw ◽  
Bone Quality ◽  
Quantitative Computed Tomography ◽  
Pedicle Screws ◽  
Fatigue Load ◽  
Head Displacement ◽  
Significant Difference ◽  
Vertebral Bodies

Abstract Purpose Inadequate anchoring of pedicle screws in vertebrae with poor bone quality is a major problem in spine surgery. The aim was to evaluate whether a modified thread in the area of the pedicle could significantly improve the pedicle screw fatigue strength. Methods Fourteen human cadaveric vertebral bodies (L2 and L3) were used for in vitro testing. Bone density (BMD) was determined by quantitative computed tomography. Vertebral bodies were instrumented by standard pedicle screws with a constant double thread on the right pedicle and a partial doubling of the threads–quad thread–(cortical thread) in the area of the pedicle on the left pedicle. Pulsating sinusoidal, cyclic load (0.5 Hz) with increasing peak force (100 N + 0.1 N/cycles) was applied orthogonal to the screw axis. The baseline force remained constant (50 N). Fatigue test was terminated after exceeding 5.4-mm head displacement (~ 20° screw tilting). Results The mean fatigue load at failure was 264.9 N (1682 cycles) for the standard screws and was increased significantly to 324.7 N (2285 cycles) by the use of cortical threaded screws (p = 0.014). This effect is particularly evident in reduced BMD (standard thread 241.2 N vs. cortical thread 328.4 N; p = 0.016), whereas in the group of vertebrae with normal BMD no significant difference could be detected (standard thread 296.5 N vs. cortical thread 319.8 N; p = 0.463). Conclusions Compared to a conventional pedicle screw, the use of a cortical threaded pedicle screw promises superior fatigue load in vertebrae with reduced bone quality.

scholarly journals Comparison of Insertion Time, Pull-out Strength, and Screw-media Interface Area of Customized Pedicle Screw With Different Core and Thread Design Against Commercial Pedicle Screw

2021 ◽  
Author(s):  
Rahadyan Magetsari ◽  
Tedjo Rukmoyo ◽  
Marda Ade Saputra ◽  
Yudha Mathan Sakti
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Insertion Time ◽  
Control Group ◽  
Interface Area ◽  
Screw Design ◽  
Pull Out ◽  
Thread Diameter ◽  
Screw Group ◽  
Pull Out Strength

Abstract Objective: This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result: The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22,94 s) with commercially available pedicle screw (15.86 s) (p<0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p<0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw.

scholarly journals Comparison of insertion time, pull-out strength, and screw-media interface area of customized pedicle screw with different core and thread design against commercial pedicle screw: a pilot study on Indonesian Population

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Rahadyan Magetsari ◽  
Tedjo Rukmoyo ◽  
Marda Ade Saputra ◽  
Yudha Mathan Sakti
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Insertion Time ◽  
Control Group ◽  
Interface Area ◽  
Screw Design ◽  
Pull Out ◽  
Indonesian Population ◽  
Thread Diameter ◽  
Pull Out Strength

Abstract Objective This research aimed to developing customized pedicle screw based on Indonesian vertebral anatomy and compare the insertion time, pull-out strength, and screw-media interface area of different screw design. We have developed 3 different types of pedicle screws (v-thread cylinder-core, square-thread cylinder-core and square-thread conical-core). The thread diameter was calculated from pedicle width of Indonesian population (6 mm). We used commercially available pedicle screw as control group (6.2 mm). Result The insertion time were significantly difference between v-thread cylinder-core pedicle screw (22.94 s) with commercially available pedicle screw (15.86 s) (p < 0.05). The pull-out strength was significantly difference between commercially available pedicle screw (408.60 N) with square-thread conical pedicle screw (836.60 N) (p < 0.05). The square-thread conical-core group have the highest interface area (1486.21 mm2). The data comparison showed that the square-thread conical-core customized pedicle screw group has comparable insertion time and has better pull-out strength than commercially available pedicle screw.

scholarly journals Določanje velikosti in vstavitvene trajektorije pedikularnih vijakov v računalniškotomografskih (CT) slikah deformacij prsne hrbtenice: primerjava ročnega in računalniško podprtega predoperacijskega načrtovanja

2017 ◽  
Vol 85 (11-12) ◽  
Author(s):  
Dejan Knez ◽  
Janez Mohar ◽  
Robert Janez Cirman ◽  
Boštjan Likar ◽  
Franjo Pernuš ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Preoperative Planning ◽  
Sagittal Plane ◽  
Pedicle Screws ◽  
Ct Images ◽  
Screw Placement ◽  
Computer Assisted ◽  
Pedicle Screw Placement ◽  
Pull Out ◽  
Significant Difference

Background: Vertebral fixation by pedicle screw placement is the most frequently applied fixation technique in spinal surgery. In this retrospective study we present a comparison of manual and computer-assisted preoperative planning of pedicle screw placement in three-dimensional (3D) computed tomography (CT) images of deformities in the thoracic spine.Methods: Manual planning of the pedicle screw size and trajectory was performed by two orthopedic surgeons using a dedicated software for preoperative planning of surgical procedures, while computer-assisted planning was performed by automated image processing and analysis techniques through the optimization of screw fastening strength. The size (diameter and length) and trajectory (pedicle crossing point, inclination in the sagittal plane, inclination in the axial plane) were obtained for 316 pedicle screws from 3D CT images of 17 patients with thoracic spinal deformities.Results: the analysis of pedicle screw parameters, obtained by two manual and one computer-assisted planning, indicated a statistically significant difference in the screw size (p < 0.05) and trajectory (p < 0.001). Computer-assisted planning proposed wider (p < 0.05) and longer (p < 0.001) screws with a higher (p < 0.001) normalized fastening strength.Conclusions: The comparison revealed consistency between manual and computer-assisted planning of the pedicle screw size and trajectory, except for the screw inclination in the sagittal plane, as manual planning followed more the straight-forward while computer-assisted planning followed more the anatomical insertion technique. While being faster, more repeatable and more reliable than manual planning, computer-assisted planning was also linked with a higher screw fastening strength and consequently a higher screw pull-out strength.

scholarly journals Possible Usage of Cannulated Pedicle Screws without Cement Augmentation

2014 ◽  
Vol 11 (3) ◽  
pp. 149-155 ◽  
Author(s):  
Teyfik Demir
Keyword(s):  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Cement Augmentation ◽  
Control Group ◽  
Pullout Strength ◽  
Screw Design ◽  
Pullout Tests ◽  
Pu Foam ◽  
Common Problems ◽  
Testing Protocols

Background: The use of pedicle screws is becoming increasingly popular for spinal surgery practice as the technology advances. Screw pullout due to bone quality and loading conditions is one of the most common problems observed after pedicle screw fixation. Several solutions were studied to prevent screw pullout. These can be investigated under three main categories: screw design, expandable screws and cement augmentation.Objective: This study aimed to investigate the pullout performance of cannulated screws without cement augmentation on synthetic foams.Methods: Artificial fusion process for PU is described and validated in our previous studies. For this study six newly designed cannulated pedicle screws were artificially fused to PU foam and pullout test were conducted according to ASTM F543 standard testing protocols.Results: According to the results of post-fusion pullout tests, worst performed cannulated screw design was S3H on healthy bone simulating PU foam. However, pullout strength of unilaterally three holes including (S3H) design was purchased with two times higher loads when compared to control group. Solid cored screws were purchased with 671 N where this value was 1450 N for S3H design.Conclusions: This study provided that using cannulated pedicle screws without cement augmentation for the cases with healthy bone can be a reliable alternative to classical screws. To the knowledge of the authors this is the first post-fusion study investigating cannulated pedicle screws without cement augmentation.

A Novel Technique for Measuring Pedicle Screw Forces In Situ

2008 ◽  
Author(s):  
Samuel Q. Tia ◽  
Jennifer M. Buckley ◽  
Thuc-Quyen Nguyen ◽  
Jeffrey C. Lotz ◽  
Shane Burch
Keyword(s):  
Pedicle Screw ◽  
Pedicle Screws ◽  
Clinical Failure ◽  
Strain Gages ◽  
Destructive Testing ◽  
Novel Technique ◽  
Pull Out ◽  
Pull Out Strength

Long posterior fusion constructs in the lumbar spine cause substantial posteriorly directed loading of the supporting pedicle screws, particularly during patient bending activities. Although there are numerous documented accounts of clinical failure at the pedicle screw-bone interface [1,2], the in situ pull-out strength of pedicle screws in long surgical constructs has not been characterized. Previous biomechanical studies have quantified pedicle screw pull-out force in cadaveric models through destructive testing or in nondestructive cases, through the use of custom-machined pedicle screws instrumented with strain gages [3–6]. However, these techniques involve altering screw geometry and may fail to properly simulate in vivo mechanical loading conditions. The goal of this study was to develop and validate a sensor system for measuring pedicle screw pull-out forces in long posterior constructs in situ during multi-segmental cadaveric testing.

Optimization of Pedicle Screw Depth in the Lumbar Spine

2013 ◽  
Author(s):  
Laura E. Buckenmeyer ◽  
Kristophe J. Karami ◽  
Ata M. Kiapour ◽  
Vijay K. Goel ◽  
Teck M. Soo ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Pedicle Screw ◽  
Pedicle Screws ◽  
Fixation Strength ◽  
Osteoporotic Patient ◽  
Insertion Depth ◽  
Anterior Cortex ◽  
Screw Insertion ◽  
Clinical Challenge ◽  
Series Of Experiments

Optimization of pedicle screw insertion depth for ideal fixation and fusion remains a clinical challenge. Improved screw purchase may improve fixation strength 1, which is especially critical in an osteoporotic patient population. Extended screw insertion depths, up to and through the anterior cortex, have yet to be compared to more commonly used shorter pedicle screws in a laboratory controlled series of experiments. The purpose of this study is to evaluate screw purchase in the osteoporotic lumbar spine as a function of insertion depth, which may be used to optimize pedicle screw-rod constructs.

scholarly journals Initial academic experience and learning curve with robotic spine instrumentation

2017 ◽  
Vol 42 (5) ◽  
pp. E4 ◽  
Author(s):  
Timur M. Urakov ◽  
Ken Hsuan-kan Chang ◽  
S. Shelby Burks ◽  
Michael Y. Wang
Keyword(s):  
Pedicle Screw ◽  
Spine Surgery ◽  
Pedicle Screws ◽  
Guidance System ◽  
Screw Placement ◽  
Fluoroscopy Time ◽  
Academic Experience ◽  
Robot Assisted ◽  
Spine Instrumentation ◽  
Significant Difference

OBJECTIVESpine surgery is complex and involves various steps. Current robotic technology is mostly aimed at assisting with pedicle screw insertion. This report evaluates the feasibility of robot-assisted pedicle instrumentation in an academic environment with the involvement of residents and fellows.METHODSThe Renaissance Guidance System was used to plan and execute pedicle screw placement in open and percutaneous consecutive cases performed in the period of December 2015 to December 2016. The database was reviewed to assess the usability of the robot by neurosurgical trainees. Outcome measures included time per screw, fluoroscopy time, breached screws, and other complications. Screw placement was assessed in patients with postoperative CT studies. The speed of screw placement and fluoroscopy time were collected at the time of surgery by personnel affiliated with the robot’s manufacturer. Complication and imaging data were reviewed retrospectively.RESULTSA total of 306 pedicle screws were inserted in 30 patients with robot guidance. The average time for junior residents was 4.4 min/screw and for senior residents and fellows, 4.02 min/screw (p = 0.61). Among the residents dedicated to spine surgery, the average speed was 3.84 min/screw, while nondedicated residents took 4.5 min/screw (p = 0.41). Evaluation of breached screws revealed some of the pitfalls in using the robot.CONCLUSIONSNo significant difference regarding the speed of pedicle instrumentation was detected between the operators’ years of experience or dedication to spine surgery, although more participants are required to investigate this completely. On the other hand, there was a trend toward improved efficiency with more cases performed. To the authors’ knowledge, this is the first reported academic experience with robot-assisted spine instrumentation.

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