A biomechanical cadaveric analysis of polymethylmethacrylate-augmented pedicle screw fixation

2007 ◽  
Vol 7 (1) ◽  
pp. 47-53 ◽  
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.

scholarly journals Cement leakage in pedicle screw augmentation: a prospective analysis of 98 patients and 474 augmented pedicle screws

2016 ◽  
Vol 25 (1) ◽  
pp. 103-109 ◽  
Author(s):  
Jan U. Mueller ◽  
Joerg Baldauf ◽  
Sascha Marx ◽  
Michael Kirsch ◽  
Henry W. S. Schroeder ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
High Volume ◽  
Cement Leakage ◽  
Pedicle Screw Fixation ◽  
Screw Loosening ◽  
Pedicle Screw Placement ◽  
Screw Augmentation ◽  
Cement Embolism

OBJECTIVE Loosening and pullout of pedicle screws are well-known problems in pedicle screw fixation surgery. Augmentation of pedicle screws with bone cement, first described as early as 1975, increases the pedicle-screw interface and pullout force in osteoporotic vertebrae. The aim of the present study was to identify cement leakage and pulmonary embolism rates in a large prospective single-center series of pedicle screw augmentations. METHODS All patients who underwent cement-augmented pedicle screw placement between May 2006 and October 2010 at the authors' institution were included in this prospective cohort study. Perivertebral cement leakage and pulmonary cement embolism were evaluated with a CT scan of the area of operation and with a radiograph of the chest, respectively. RESULTS A total of 98 patients underwent placement of cement-augmented pedicle screws; 474 augmented screws were inserted in 237 vertebrae. No symptomatic perivertebral cement leakage or symptomatic pulmonary cement embolism was observed, but asymptomatic perivertebral cement leakage was seen in 88 patients (93.6%) and in 165 augmented vertebrae (73.3%). Cement leakage most often occurred in the perivertebral venous system. Clinically asymptomatic pulmonary cement embolism was found in 4 patients (4.1%). CONCLUSIONS Perivertebral cement leakage often occurs in pedicle screw augmentation, but in most cases, it is clinically asymptomatic. Cement augmentation should be performed under continuous fluoroscopy to avoid high-volume leakage. Alternative strategies, such as use of expandable screws, should be examined in more detail for patients at high risk of screw loosening.

scholarly journals The effect of denosumab on pedicle screw fixation: a prospective 2-year longitudinal study using finite element analysis

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Soji Tani ◽  
Koji Ishikawa ◽  
Yoshifumi Kudo ◽  
Koki Tsuchiya ◽  
Akira Matsuoka ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elderly Patients ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Pullout Strength ◽  
Mineral Density ◽  
Element Analysis ◽  
Denosumab Treatment

Abstract Background Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis. Methods This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation. Results BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months). Conclusion To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.

Minimally Invasive Single-Position Lateral Interbody Fusion With Robotic Bilateral Percutaneous Pedicle Screw Fixation: 2-Dimensional Operative Video

2018 ◽  
Vol 16 (4) ◽  
pp. E121-E121 ◽  
Author(s):  
Corey T Walker ◽  
Jakub Godzik ◽  
David S Xu ◽  
Nicholas Theodore ◽  
Juan S Uribe ◽  
...  
Keyword(s):  
Minimally Invasive ◽  
Pedicle Screw ◽  
Interbody Fusion ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Screw Placement ◽  
Lateral Interbody Fusion ◽  
Percutaneous Pedicle Screw ◽  
Percutaneous Pedicle Screw Fixation ◽  
Lateral Interbody

Abstract Lateral interbody fusion has distinct advantages over traditional posterior approaches. When adjunctive percutaneous pedicle screw fixation is required, placement from the lateral decubitus position theoretically increases safety and improves operative efficiency by obviating the need for repositioning. However, safe cannulation of the contralateral, down-side pedicles remains technically challenging and often prohibitive. In this video, we present the case of a 59-yr-old man with refractory back pain and bilateral lower extremity radiculopathy that was worse on the left than right side. The patient provided written informed consent before undergoing treatment. We performed minimally invasive single-position lateral interbody fusion with robotic (ExcelsiusGPS, Globus Medical Inc, Audubon, Pennsylvania) bilateral percutaneous pedicle screw fixation for the treatment of asymmetric disc degeneration, dynamic instability, and left paracentral disc herniation with corresponding stenosis at the L3-4 level. A left-sided minimally invasive transpsoas lateral interbody graft was placed with fluoroscopic guidance. Without changing the position of the patient or breaking the sterile field, an intraoperative cone-beam computed tomography image was obtained for navigational screw placement with stereotactic trackers in the iliac spine. Screw trajectories were planned using the robotic navigation software and were placed percutaneously in the bilateral L3 and L4 pedicles using the robotic arm. Concomitant lateral fluoroscopy may be used if desired to ensure the fidelity of the robotic guidance. The patient recovered well postoperatively and was discharged home within 36 h, without complication. Single-position lateral interbody fusion and percutaneous pedicle screw fixation can be accomplished using robotic-assisted navigation and pedicle screw placement. Used with permission from Barrow Neurological Institute.

Finite Element Study to Evaluate the Biomechanical Performance of the Spine After Augmenting Percutaneous Pedicle Screw Fixation With Kyphoplasty in the Treatment of Burst Fractures

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Shady S. Elmasry ◽  
Shihab S. Asfour ◽  
Francesco Travascio
Keyword(s):  
Finite Element ◽  
Pedicle Screw ◽  
Fatigue Testing ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Thoracolumbar Burst Fractures ◽  
Hardware Failure ◽  
Burst Fractures ◽  
Percutaneous Pedicle Screw ◽  
Percutaneous Pedicle Screw Fixation

Percutaneous pedicle screw fixation (PPSF) is a well-known minimally invasive surgery (MIS) employed in the treatment of thoracolumbar burst fractures (TBF). However, hardware failure and loss of angular correction are common limitations caused by the poor support of the anterior column of the spine. Balloon kyphoplasty (KP) is another MIS that was successfully used in the treatment of compression fractures by augmenting the injured vertebral body with cement. To overcome the limitations of stand-alone PPSF, it was suggested to augment PPSF with KP as a surgical treatment of TBF. Yet, little is known about the biomechanical alteration occurred to the spine after performing such procedure. The objective of this study was to evaluate and compare the immediate post-operative biomechanical performance of stand-alone PPSF, stand-alone-KP, and KP-augmented PPSF procedures. Novel three-dimensional (3D) finite element (FE) models of the thoracolumbar junction that describes the fractured spine and the three investigated procedures were developed and tested under mechanical loading conditions. The spinal stiffness, stresses at the implanted hardware, and the intradiscal pressure at the upper and lower segments were measured and compared. The results showed no major differences in the measured parameters between stand-alone PPSF and KP-augmented PPSF procedures, and demonstrated that the stand-alone KP may restore the stiffness of the intact spine. Accordingly, there was no immediate post-operative biomechanical advantage in augmenting PPSF with KP when compared to stand-alone PPSF, and fatigue testing may be required to evaluate the long-term biomechanical performance of such procedures.

scholarly journals Posterior monoaxial screw fixation combined with distraction-compression technology assisted endplate reduction for thoracolumbar burst fractures: a retrospective study

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Xuhong Xue ◽  
Sheng Zhao
Keyword(s):  
Retrospective Study ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
Thoracolumbar Burst Fractures ◽  
Correction Rate ◽  
Burst Fractures ◽  
The Mean

Abstract Background The management of thoracolumbar burst fractures traditionally involves posterior pedicle screw fixation, but it has some drawbacks. The aim of this study is to evaluate the clinical and radiological outcomes of patients with thoracolumbar burst fractures. They were treated by a modified technique that monoaxial pedicle screws instrumentation and distraction-compression technology assisted end plate reduction. Methods From March 2014 to February 2016, a retrospective study including 42 consecutive patients with thoracolumbar burst fractures was performed. The patients had undergone posterior reduction and instrumentation with monoaxial pedicle screws. The fractured vertebrae were also inserted screws as a push point. The distraction -compression technology was used as assisting end plate reduction. All patients were followed up at a minimum of 2 years. These parameters including segmental kyphosis, severity of fracture, neurological function, canal compromise and back pain were evaluated in preoperatively, postoperatively and at the final follow-up. Results The average follow-up period was 28.9 ± 4.3 months (range, 24-39mo). No patients had postoperative implant failure at recent follow-up. The mean Cobb angle of the kyphosis was improved from 14.2°to 1.1° (correction rate 92.1%). At final follow-up there was 1.5% loss of correction. The mean preoperative wedge angle was improved from 17.1 ± 7.9°to 4.4 ± 3.7°(correction rate 74.3%). The mean anterior and posterior vertebral height also showed significant improvements postoperatively, which were maintained at the final follow-up(P < 0.05). The mean visual analogue scale (VAS) scores was 8 and 1.6 in preoperation and at the last follow-up, and there was significant difference (p < 0.05). Conclusion Based on our experience, distraction-compression technology can assist reduction of collapsed endplate directly. Satisfactory fracture reduction and correction of segmental kyphosis can be achieved and maintained with the use of monoaxial pedicle screw fixation including the fractured vertebra. It may be a good treatment approach for thoracolumbar burst fractures.

Removal of broken pedicle screws

2001 ◽  
Vol 95 (1) ◽  
pp. 150-151 ◽  
Author(s):  
Kei Miyamoto ◽  
Katsuji Shimizu ◽  
Ken Kouda ◽  
Hideo Hosoe
Keyword(s):  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
Pedicle Screw Fixation ◽  
New Method ◽  
Content Type ◽  
Screw Hole ◽  
Narrow Slot ◽  
Power Drill ◽  
Diamond Burr

✓ The authors describe a simple, new method for removing broken pedicle screws. Under microscopic visualization a straight, narrow slot is etched in the broken surface of the pedicle screw by using a power drill with a 2-mm diamond burr. A minus screwdriver is then inserted into the slot, and the broken screw is rotated and removed. There is no need to enlarge the screw hole around the broken screw or to use any special devices. The authors succeeded in removing broken screws in two cases, and there were no complications. This method allows preservation of both the pedicle and the screw hole. Consequently, it is possible to insert new pedicle screws into the same hole without losing the strength and stability of pedicle screw fixation. The authors recommend this simple and new method for removal of broken pedicle screws.

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

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
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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