Novel Biodegradable Composite of Calcium Phosphate Cement and the Collagen I Mimetic P-15 for Pedicle Screw Augmentation in Osteoporotic Bone

Osteoporotic vertebral fractures often necessitate fusion surgery, with high rates of implant failure. We present a novel bioactive composite of calcium phosphate cement (CPC) and the collagen I mimetic P-15 for pedicle screw augmentation in osteoporotic bone. Methods involved expression analysis of osteogenesis-related genes during osteoblastic differentiation by RT-PCR and immunostaining of osteopontin and Ca2+ deposits. Untreated and decalcified sheep vertebrae were utilized for linear pullout testing of pedicle screws. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DEXA). Expression of ALPI II (p < 0.0001), osteopontin (p < 0.0001), RUNX2 (p < 0.0001), and osteocalcin (p < 0.0001) was upregulated after co-culture of MSC with CPC-P-15. BMD was decreased by 28.75% ± 2.6%. Pullout loads in untreated vertebrae were 1405 ± 6 N (p < 0.001) without augmentation, 2010 ± 168 N (p < 0.0001) after augmentation with CPC-P-15, and 2112 ± 98 N (p < 0.0001) with PMMA. In decalcified vertebrae, pullout loads were 828 ± 66 N (p < 0.0001) without augmentation, 1324 ± 712 N (p = 0.04) with PMMA, and 1252 ± 131 N (p < 0.0078) with CPC-P-15. CPC-P-15 induces osteoblastic differentiation of human MES and improves pullout resistance of pedicle screws in osteoporotic and non-osteoporotic bone.

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Comparison of the Pullout Strength of Different Pedicle Screw Designs and Augmentation Techniques in an Osteoporotic Bone Model

Asian Spine Journal ◽

10.4184/asj.2018.12.1.3 ◽

2018 ◽

Vol 12 (1) ◽

pp. 3-11 ◽

Cited By ~ 7

Author(s):

Gorkem Kiyak ◽

Tevfik Balikci ◽

Ahmed Majid Heydar ◽

Murat Bezer

Keyword(s):

Calcium Phosphate ◽

Pedicle Screw ◽

Calcium Phosphate Cement ◽

Pedicle Screws ◽

Osteoporotic Bone ◽

Cannulated Screws ◽

Pullout Strength ◽

Pullout Force ◽

Bone Screw ◽

Augmentation Techniques

<sec><title>Study Design</title>Mechanical study.</sec><sec><title>Purpose</title>To compare the pullout strength of different screw designs and augmentation techniques in an osteoporotic bone model.</sec><sec><title>Overview of Literature</title>Adequate bone screw pullout strength is a common problem among osteoporotic patients. Various screw designs and augmentation techniques have been developed to improve the biomechanical characteristics of the bone–screw interface.</sec><sec><title>Methods</title>Polyurethane blocks were used to mimic human osteoporotic cancellous bone, and six different screw designs were tested. Five standard and expandable screws without augmentation, eight expandable screws with polymethylmethacrylate (PMMA) or calcium phosphate augmentation, and distal cannulated screws with PMMA and calcium phosphate augmentation were tested. Mechanical tests were performed on 10 unused new screws of each group. Screws with or without augmentation were inserted in a block that was held in a fixture frame, and a longitudinal extraction force was applied to the screw head at a loading rate of 5 mm/min. Maximum load was recorded in a load displacement curve.</sec><sec><title>Results</title>The peak pullout force of all tested screws with or without augmentation was significantly greater than that of the standard pedicle screw. The greatest pullout force was observed with 40-mm expandable pedicle screws with four fins and PMMA augmentation. Augmented distal cannulated screws did not have a greater peak pullout force than nonaugmented expandable screws. PMMA augmentation provided a greater peak pullout force than calcium phosphate augmentation.</sec><sec><title>Conclusions</title>Expandable pedicle screws had greater peak pullout forces than standard pedicle screws and had the advantage of augmentation with either PMMA or calcium phosphate cement. Although calcium phosphate cement is biodegradable, osteoconductive, and nonexothermic, PMMA provided a significantly greater peak pullout force. PMMA-augmented expandable 40-mm four-fin pedicle screws had the greatest peak pullout force.</sec>

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Study on the application of internal fixation material implantation in the rehabilitation of spondylolisthesis in children

Materials Express ◽

10.1166/mex.2021.2011 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1366-1372

Author(s):

Yongliang Liu ◽

Caijuan Chu ◽

Hua Gao ◽

Hong Jing

Keyword(s):

Bone Marrow ◽

High Pressure ◽

Calcium Phosphate ◽

Bone Cement ◽

Pedicle Screw ◽

Calcium Phosphate Cement ◽

Clinical Studies ◽

Pedicle Screws ◽

New Type ◽

Good Biocompatibility

Spondylolisthesis (SP), particularly lumbar SP in children, is mostly caused by dysplasia. Several clinical studies have revealed that bone cement filled with hollow pedicle screws can achieve great benefits in the treatment of SP. However, most of the existing bone cement materials are based on polymethyl methacrylate (PMMA) and calcium phosphate cement (CPC). However, PMMA has poor biocompatibility, due to which its actual efficacy is greatly reduced. Although CPC has good biocompatibility, it exhibits certain cytotoxicity and high pressure in the bone marrow, resulting in fat droplets in blood vessels, which may cause embolisms. This study aimed to investigate the actual efficacy of a new type of bone nanocement filled with hollow pedicle screw in the treatment of 11 children with lumbar SP and to provide a feasible surgical method for the treatment of lumbar SP with hollow pedicle screw filled with bone nanocement.

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A biomechanical cadaveric analysis of polymethylmethacrylate-augmented pedicle screw fixation

Journal of Neurosurgery Spine ◽

10.3171/spi-07/07/047 ◽

2007 ◽

Vol 7 (1) ◽

pp. 47-53 ◽

Cited By ~ 91

Author(s):

Bruce M. Frankel ◽

Sabino D'Agostino ◽

Chiang Wang

Keyword(s):

Pedicle Screw ◽

Screw Fixation ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Screw Placement ◽

Pullout Strength ◽

Mineral Density ◽

Hardware Failure ◽

Screw Augmentation ◽

Valuable Adjunct

Object Instrumentation of the osteoporotic spine can be fraught with complications such as hardware failure. A cadaver study was performed to determine the biomechanical performance of polymethylmethacrylate (PMMA)–augmented pedicle screws. Methods Three osteoporotic human cadaveric specimens with a mean bone mineral density of 0.70 g/cm2 were used to evaluate the performance of a novel fenestrated bone tap in pedicle screw augmentation. On this device, tap threads serve a dual purpose in preventing backflow of cement toward neural elements while allowing for a custom form for subsequent screw placement. The tap was used to inject a mean volume of 3.7 ml PMMA/pedicle (range 2–8.0 ml PMMA/pedicle) followed by pedicle screw placement between L-5 and T-5, alternating between augmented and nonaugmented instrumentation. Axial pullout testing was then performed. Results Pedicle screw pullout strength was increased in both primary and salvage procedures by 119% (p = 0.001) and 162% (p = 0.01), respectively, after PMMA augmentation. Additionally, the injected cement volumes were divided into two groups, a low-cement group (≤ 2.8 ml/pedicle) and a high-cement group (≥ 5.5 ml/pedicle). Interestingly, the pullout strength did not significantly change with increased cement usage between the two groups (p > 0.05 for all comparisons). Conclusions Polymethylmethacrylate-augmented pedicle screw fixation results in a significant increase in the axial pullout strength of augmented pedicle screws in both primary and revision procedures. This technique may be a valuable adjunct in cases in which bolstering of the screw–bone interface is necessary.

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Selenium-modified calcium phosphate cement can accelerate bone regeneration of osteoporotic bone defect

Journal of Bone and Mineral Metabolism ◽

10.1007/s00774-021-01240-3 ◽

2021 ◽

Author(s):

Tian-Lin Li ◽

Zhou-Shan Tao ◽

Xing-jing Wu ◽

Min Yang ◽

Hong-Guang Xu

Keyword(s):

Calcium Phosphate ◽

Bone Regeneration ◽

Bone Defect ◽

Calcium Phosphate Cement ◽

Osteoporotic Bone

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The Correlation between Insertion Torque of Pedicle Screws with Bone Mineral Density Values in Posterior Lumbar Pedicle Screw Fixation

The Spine Journal ◽

10.1016/j.spinee.2011.08.352 ◽

2011 ◽

Vol 11 (10) ◽

pp. S145-S146 ◽

Cited By ~ 2

Author(s):

Jae Hyup Lee ◽

Jae-Woo Park ◽

Ji-Ho Lee ◽

Hye Soo Lee

Keyword(s):

Bone Mineral Density ◽

Pedicle Screw ◽

Bone Mineral ◽

Screw Fixation ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Insertion Torque ◽

Mineral Density ◽

Density Values ◽

Lumbar Pedicle

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

ASME 2010 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2010-19121 ◽

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.

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Placement of Guide-Wireless Sharp Percutaneous Pedicle Screws Utilizing Computed Tomography-Navigation and Sentinel Fluoroscopy: 2-Dimensional Operative Video

Operative Neurosurgery ◽

10.1093/ons/opz361 ◽

2019 ◽

Vol 19 (2) ◽

pp. E149-E150 ◽

Cited By ~ 1

Author(s):

Nikolay L Martirosyan ◽

Joshua T Wewel ◽

Juan S Uribe

Keyword(s):

Computed Tomography ◽

Pedicle Screw ◽

Pedicle Screws ◽

Transverse Process ◽

Screw Placement ◽

Osteoporotic Bone ◽

Screw Insertion ◽

Institutional Review ◽

Stab Incision ◽

Anterior Posterior

Abstract Many established techniques exist for minimally invasive pedicle screw placement. Nearly all techniques incorporate the use of a Kershner wire (K-wire) at various points in the work-flow. The use of a K-wire adds an additional step. If its position is lost, it requires repeating all previous steps, and placement is not without complication. The use of a guide-wireless sharp screws allows the surgeon to place a pedicle screw in 1 step with several fluid maneuvers.1 The patient underwent Institutional Review Board-approved consent for this study. Following traditional computed tomography-based navigation, a stab incision is made, followed by fascial dissection with monopolar cautery. The sharp screw is placed percutaneously at the facet-transverse process junction. The precise entry point is confirmed with navigation, followed by a sentinel anterior-posterior fluoroscopic image, verifying the accuracy of the navigation. The cortical bone is traversed by malleting the sharp tip through the cortex. When the cancellous bone is engaged, the screw is then advanced through the pedicle. This set of steps allows for safe, efficient placement of percutaneous pedicle screws without the need for a guidewire. Mal-placement regarding sharp pedicle screw insertion is similar to K-wire-dependent screw placement. Surgeons must be cognoscente of exceptionally sclerotic bone, which can prove difficult to cannulate. Conversely, osteoporotic bone that is liable to a cortical pedicle breach, transverse process fracture, and/or maltrajectory are all considerations when placing a K-wireless, sharp pedicle screw. Anterior-posterior fluoroscopy is utilized to confirm accuracy of image-guided navigation and mitigate malplacement of pedicle screws.

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Augmentation of pedicle screw fixation with calcium phosphate cement

Journal of Wuhan University of Technology-Mater Sci Ed ◽

10.1007/bf03000160 ◽

2004 ◽

Vol 19 (2) ◽

pp. 20-23

Author(s):

Shu-hua Yang ◽

De-hao Fu ◽

Jin Li ◽

Wei-hua Xu ◽

Cao Yang ◽

...

Keyword(s):

Calcium Phosphate ◽

Pedicle Screw ◽

Calcium Phosphate Cement ◽

Screw Fixation ◽

Pedicle Screw Fixation

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Balancing Rigidity and Safety of Pedicle Screw Fixation via a Novel Expansion Mechanism in a Severely Osteoporotic Model

BioMed Research International ◽

10.1155/2015/318405 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 2

Author(s):

Thomas M. Shea ◽

James J. Doulgeris ◽

Sabrina A. Gonzalez-Blohm ◽

William E. Lee ◽

Kamran Aghayev ◽

...

Keyword(s):

Cortical Bone ◽

Pedicle Screw ◽

Pedicle Screws ◽

Pedicle Screw Fixation ◽

Cortical Layer ◽

Fixation Strength ◽

Osteoporotic Bone ◽

Pullout Strength ◽

Initial Fixation ◽

Increased Risk

Many successful attempts to increase pullout strength of pedicle screws in osteoporotic bone have been accompanied with an increased risk of catastrophic damage to the patient. To avoid this, a single-armed expansive pedicle screw was designed to increase fixation strength while controlling postfailure damage away from the nerves surrounding the pedicle. The screw was then subsequently tested in two severely osteoporotic models: one representing trabecular bone (with and without the presence of polymethylmethacrylate) and the other representing a combination of trabecular and cortical bone. Maximum pullout strength, stiffness, energy to failure, energy to removal, and size of the resulting block damage were statistically compared among conditions. While expandable pedicle screws produced maximum pullout forces less than or comparable to standard screws, they required a higher amount of energy to be fully removed from both models. Furthermore, damage to the cortical layer in the composite test blocks was smaller in all measured directions for tests involving expandable pedicle screws than those involving standard pedicle screws. This indicates that while initial fixation may not differ in the presence of cortical bone, the expandable pedicle screw offers an increased level of postfailure stability and safety to patients awaiting revision surgery.

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