Augmented PMMA distribution: improvement of mechanical property and reduction of leakage rate of a fenestrated pedicle screw with diameter-tapered perforations

OBJECTIVE This study investigated the optimum injection volume of polymethylmethacrylate (PMMA) to augment a novel fenestrated pedicle screw (FPS) with diameter-tapered perforations in the osteoporotic vertebral body, and how the distribution characteristics of PMMA affect the biomechanical performance of this screw. METHODS Two types of FPSs were designed (FPS-A, composed of 6 perforations with an equal diameter of 1.2 mm; and FPS-B, composed of 6 perforations each with a tapered diameter of 1.5 mm, 1.2 mm, and 0.9 mm from tip to head. Each of 28 human cadaveric osteoporotic vertebrae were randomly assigned to 1 of 7 groups: FPS-A1.0: FPS-A+1.0 ml PMMA; FPS-A1.5: FPS-A+1.5 ml PMMA; FPS-A2.0: FPS-A+2.0 ml PMMA; FPS-B1.0: FPS-B+1.0 ml PMMA; FPS-B1.5: FPS-B+1.5 ml PMMA; FPS-B2.0: FPS-B+2.0 ml PMMA; and conventional pedicle screws (CPSs) without PMMA. After the augmentation, 3D CT was performed to assess the cement distribution characteristics and the cement leakage rate. Axial pullout tests were performed to compare the maximum pullout force thereafter. RESULTS The CT construction images showed that PMMA bone cement formed a conical mass around FPS-A and a cylindrical mass around FPS-B. When the injection volume was increased from 1.0 ml to 2.0 ml, the distribution region of the PMMA cement was enlarged, the PMMA was distributed more posteriorly, and the risk of leakage was increased. When the injection volume reached 2.0 ml, the risk of cement leakage was lower for screws having diameter-tapered perforations. The pullout strengths of the augmented FPS-A groups and FPS-B groups were higher than that of the CPS group (p < 0.0001). All FPS-B groups had a higher pullout strength than the FPS-A groups. CONCLUSIONS The diameter of the perforations affects the distribution of PMMA cement. The diameter-tapered design enabled PMMA to form larger bone-PMMA interfaces and achieve a relatively higher pullout strength, although statistical significance was not reached. Study results indicated 1.5-ml of PMMA was a conservative volume for PMMA augmentation; more cement injection would significantly increase the risk of cement leakage.

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The Role of Prophylactic Vertebroplasty at UIV+1 and Cement-augmented Fenestrated Pedicle Screw for Prevention of PJK/PJF in Patients With Osteoporosis: A Propensity Score–matched Analysis

10.21203/rs.3.rs-73483/v1 ◽

2020 ◽

Author(s):

Qi Wang ◽

Chi Wang ◽

Wenhao Hu ◽

Fanqi Hu ◽

Weibo Liu ◽

...

Keyword(s):

Propensity Score ◽

Pedicle Screw ◽

Adult Spinal Deformity ◽

Cement Leakage ◽

Cement Augmentation ◽

Screw Loosening ◽

Group A ◽

Pedicle Screw Loosening ◽

Fenestrated Pedicle Screw

Abstract Objective: To elucidate the role of prophylactic vertebroplasty (PV) at UIV+1 and cement-augmented fenestrated pedicle screw (CAFPS) in prevention of PJK and PJF.Background: Cement augmentation at UIV and UIV+1 was found to prevent PJK and PJF. But most studies are retrospective and have a selection bias due to multifactorial etiology of PJF, making it difficult to identify the efficacy of prophylactic cement augmentation. Methods: We enrolled 208 surgically treated adult spinal deformity (ASD) patients who were followed for at least 2 years, to elucidate whether prophylactic cement augmentation was truly minimizing the risk of PJK and PJF in a uniform population from one center database. Patients were classified into two groups. Two comparable groups were propensity-matched with one to one nearest neighbor matching. The main outcome variables including PJK, PJF, pedicle screw loosening and cement leakage were compared.Results：After propensity score matching, there were 58 propensity-matched patients in group A and B (n=29 in each group) whose parameters including age, BMI, BMD, number of instrumented vertebrae, SVA, spinal-pelvic parameters and the frequency of UIV and LIV were similar. The incidence of PJK showed no significantly statistical difference between group A and B (10.3% vs 13.8%, p >0.99). Compared to group A, group B had a higher proportion of patients developing PJF (24.1% vs 0%, p=0.01). Pedicle screw loosening at UIV and (or) LIV showed no difference (24.1% vs 3.4%, p=0.052) between two groups. In group A, cement leakage was detected in 5 cases via fluoroscopy, but none of them had neurological deficit or pulmonary cement embolism.Conclusion: Combined application of CAFPS and PV could reduce the incidence of PJF, but it could not prevent the development of PJK in the surgical management of ASD with low BMD or osteoporosis.

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A Novel Bone Cement Injector Augments Osteoporotic Lumbar Pedicle Screw Channel: A Biomechanical Investigation

10.21203/rs.3.rs-1035960/v1 ◽

2021 ◽

Author(s):

Suochao Fu ◽

Yu Zhang ◽

Fuzhi Ai ◽

Jianhua Wang ◽

Zenghui Wu ◽

...

Keyword(s):

Bone Cement ◽

Pedicle Screw ◽

Statistical Significance ◽

Cement Leakage ◽

Full Length ◽

Control Group ◽

Insertion Torque ◽

Screw Channel ◽

Pull Out ◽

Lumbar Pedicle

Abstract Background: The study aimed to invent a series of pedicle injectors and investigated the effects of the injectors with different number of holes on the augmentation of pedicle screw using bone cement in osteoporotic lumbar pedicle channel.Methods: This study used the biomechanical test module of polyurethane (Pacific Research Laboratory Corp, USA) to simulate the mechanical properties of human osteoporotic cancellous bone. The bone cement injectors were invented based on anatomical parameters of lumbar pedicle in Chinese. Mechanical test experiments were divided into three groups, namely, a local augmentation group, a full-length augmentation group, and a control group. The local augmentation group included three subgroups including 4 holes, 6 holes, and 8 holes and all holes were laterally placed. The full-length augmentation group was a straight-hole injector. The control group was defined that pedicle screws were inserted without any cement augmentation. Six screws were inserted in each group and the maximum insertion torque was recorded. After 24 hours of injecting acrylic bone cement, routine X-ray and CT examinations were performed to evaluate the distribution of bone cement. The axial pull-out force of screws was tested with the help of the MTS 858 mechanical tester.Results: The bone cement injectors were consisted of the sheaths and the steel-rods and the sheaths had different number of lateral holes. The control group had the lowest maximum insertion torque as compared with the 4-hole, 6-hole, 8-hole, and straight pore groups (P<0.01), but the difference between the 4-hole, 6-hole, 8-hole, and straight pore groups was no statistical significance. The control group had the lowest maximum axial pull-out force as compared with the other four groups (P<0.01). Subgroup analysis showed the 8-hole group (161.35±27.17 N) had the lower maximum axial pull-out force as compared with the 4-hole (217.29±49.68 N), 6-hole (228.39±57.83 N), and straight pore groups (237.55±35.96 N) (P<0.01). Bone cement was mainly distributed in 1/3 of the distal end of the screw among the 4-hole group, in the middle 1/3 and distal end of the screw among the 6-hole group, in the proximal 1/3 of the screw among the 8-hole group, and along the long axis of the whole screw body in the straight pore group. It might indicate that the 8-hole and straight-hole groups were more vulnerable to spinal canal cement leakage. After pullout, bone cement was also closely connected with the screw without any looseness or fragmentation.Conclusions: The bone cement injectors with different number of holes can be used to augment the pedicle screw channel. The pedicle screw augmented by the 4-hole or 6-hole sheath may have similar effects to the straight pore injector. However, the 8-hole injector may result in relatively lower pull-out strength and the straight pore injector has the risks of cement leakage as well as cement solidarization near the screw head.

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Percutaneous curved vertebroplasty in the treatment of thoracolumbar osteoporotic vertebral compression fractures

Journal of International Medical Research ◽

10.1177/0300060519836917 ◽

2019 ◽

Vol 47 (6) ◽

pp. 2424-2433 ◽

Cited By ~ 1

Author(s):

Yonghong Cheng ◽

Yiming Liu

Keyword(s):

Bone Cement ◽

Cement Leakage ◽

Leakage Rate ◽

Vertebral Compression Fractures ◽

Osteoporotic Vertebral Compression Fractures ◽

Injection Volume ◽

X Ray ◽

Compression Fractures ◽

Cement Injection ◽

Vas Scores

Objective To evaluate the clinical efficacy of percutaneous curved vertebroplasty (PCVP) in treating thoracic and lumbar osteoporotic vertebral compression fractures (OVCFs). Methods Patients with thoracolumbar OVCFs were recruited and randomly divided into three treatment groups: PCVP, unilateral percutaneous vertebroplasty (PVP) or bilateral PVP. Bone cement dispersion in the fractured vertebrae was observed. Surgery duration, X-ray frequency, bone cement injection volume, bone cement leakage rate and visual analogue scale (VAS) scores were recorded. Results Among 78 patients included, surgery duration and X-ray frequency were significantly lower in the PCVP and unilateral PVP groups versus bilateral PVP group. Bone cement injection volume was significantly higher in the bilateral PVP group (6.3 ± 1.4 ml) versus unilateral PVP (3.5 ± 1.1 ml) and PCVP groups (4.6 ± 1.2 ml). VAS scores at 24 h and 3 months post-surgery were significantly decreased versus baseline in all groups. The bone cement leakage rate was lowest in the PCVP group (8.8% [3/34 patients]). Conclusion PCVP is associated with reduced trauma, less complicated surgery with shorter duration, fewer X-rays, lower complication rate, and quicker postoperative recovery versus unilateral and bilateral PVP.

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Relationship of mammographic densities to breast cancer risk

Egyptian Journal of Radiology and Nuclear Medicine ◽

10.1186/s43055-021-00497-y ◽

2021 ◽

Vol 52 (1) ◽

Author(s):

Engy A. Ali ◽

Mariam Raafat

Keyword(s):

Breast Cancer ◽

Breast Density ◽

Statistical Significance ◽

Significant Risk ◽

Close Relation ◽

Mammographic Screening ◽

Mammographic Breast Density ◽

Study Results ◽

Relationship Of ◽

Mammographic Densities

Abstract Background Our goal was to find out the relation between mammographic densities and cancer of the breast according to the recent ACR classification. From the medical records of Kasereliny Hospital, 49,409 women were subjected to digital mammography for screening, of which 1500 breast cancer cases were collected. The mammographic categories of breast density were ACR-A, B, C, and D, which were detected by two senior radiologists. All radiological classifications were made using both standard mammographic views bilaterally. Two-sided tests of statistical significance were represented by all the P values. Results From 2014 to 2019, 49,409 women came for digital mammographic screening, their age ranges between 40 and 65, and all of them are included in the study. One thousand cases of breast cancer cases were radiologically and pathologically diagnosed. Different densities were arranged in descending pattern depending on the frequency of positive cases: D (13.7%), C (3.3%), B (2.7%), A (2.2%). There is positive significant risk ratio among every higher mammographic density in comparison to the lower density. Conclusion Our study results show that the risk of breast cancer is in close relation to the mammographic breast density.

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Assessment of pedicle screw pullout strength based on various screw designs and bone densities—an ex vivo biomechanical study

The Spine Journal ◽

10.1016/j.spinee.2012.01.014 ◽

2012 ◽

Vol 12 (2) ◽

pp. 164-168 ◽

Cited By ~ 65

Author(s):

Young-Yul Kim ◽

Woo-Sung Choi ◽

Kee-Won Rhyu

Keyword(s):

Pedicle Screw ◽

Ex Vivo ◽

Biomechanical Study ◽

Pullout Strength ◽

Strength Based

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Design and Mechanical Evaluation of Sutureless Implants for the Surgery Treatment of Rotator Cuff Tears

Journal of Biomechanical Engineering ◽

10.1115/1.4051230 ◽

2021 ◽

Author(s):

Marcília Valéria Guimarães ◽

Elton Bonifácio ◽

Thiago Carmo ◽

Cleudmar Araújo

Keyword(s):

Rotator Cuff ◽

Mechanical Behavior ◽

Functional Disability ◽

Statistical Significance ◽

Testing Machine ◽

Rotator Cuff Tears ◽

Suture Anchors ◽

Pullout Strength ◽

Rigid Foam ◽

Pullout Tests

Abstract Rotator cuff (RC) tears cause pain and functional disability of the shoulder. Despite advances in suture anchors, there are still reports about the incidence of surgical-related injuries to RC mainly associated with sutures. The purpose of this study was to design and evaluate the mechanical behavior of sutureless implants to repair RC tears. We hypothesized that the implants present mechanical characteristics suitable for the surgical treatment of RC tears as suture anchors. Three different implants (T1,T2,T3) were designed and fabricated with titanium: T1 has two rods and rectangular head; T2 has two rods with a small opening and enlarged rectangular head and T3 has three rods and a circular head. The implants were fixed in rigid polyurethane foam blocks by a series of blows, and the applied mechanical loads along with the number of blows were quantified. Pullout tests using tapes fixed between the implant head and testing machine grip were conducted until implant failure. The maximum pullout strength and displacement of the implant relative to the rigid foam block were computed. Statistical significance was set at p < 0.05. Owing to its geometric configuration, implant T2 presented the best characteristics related to stability, strength, and ease of insertion. Implant T2 confirms our hypothesis that its mechanical behavior is compatible with that of suture anchors which could lead to the reduction of RC repair failures and simplify the arthroscopic procedure.

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Adjacent-segment effects of lumbar cortical screw–rod fixation versus pedicle screw–rod fixation with and without interbody support

Journal of Neurosurgery Spine ◽

10.3171/2020.11.spine20977 ◽

2021 ◽

pp. 1-7

Author(s):

Piyanat Wangsawatwong ◽

Anna G. U. Sawa ◽

Bernardo de Andrada Pereira ◽

Jennifer N. Lehrman ◽

Luke K. O’Neill ◽

...

Keyword(s):

Pedicle Screw ◽

Interbody Fusion ◽

Lumbar Fusion ◽

Statistical Significance ◽

Adjacent Segment ◽

Lumbar Interbody Fusion ◽

Lateral Bending ◽

Single Level ◽

Cortical Screw ◽

Flexion Extension

OBJECTIVE Cortical screw–rod (CSR) fixation has emerged as an alternative to the traditional pedicle screw–rod (PSR) fixation for posterior lumbar fixation. Previous studies have concluded that CSR provides the same stability in cadaveric specimens as PSR and is comparable in clinical outcomes. However, recent clinical studies reported a lower incidence of radiographic and symptomatic adjacent-segment degeneration with CSR. No biomechanical study to date has focused on how the adjacent-segment mobility of these two constructs compares. This study aimed to investigate adjacent-segment mobility of CSR and PSR fixation, with and without interbody support (lateral lumbar interbody fusion [LLIF] or transforaminal lumbar interbody fusion [TLIF]). METHODS A retroactive analysis was done using normalized range of motion (ROM) data at levels adjacent to single-level (L3–4) bilateral screw–rod fixation using pedicle or cortical screws, with and without LLIF or TLIF. Intact and instrumented specimens (n = 28, all L2–5) were tested using pure moment loads (7.5 Nm) in flexion, extension, lateral bending, and axial rotation. Adjacent-segment ROM data were normalized to intact ROM data. Statistical comparisons of adjacent-segment normalized ROM between two of the groups (PSR followed by PSR+TLIF [n = 7] and CSR followed by CSR+TLIF [n = 7]) were performed using 2-way ANOVA with replication. Statistical comparisons among four of the groups (PSR+TLIF [n = 7], PSR+LLIF [n = 7], CSR+TLIF [n = 7], and CSR+LLIF [n = 7]) were made using 2-way ANOVA without replication. Statistical significance was set at p < 0.05. RESULTS Proximal adjacent-segment normalized ROM was significantly larger with PSR than CSR during flexion-extension regardless of TLIF (p = 0.02), or with either TLIF or LLIF (p = 0.04). During lateral bending with TLIF, the distal adjacent-segment normalized ROM was significantly larger with PSR than CSR (p < 0.001). Moreover, regardless of the types of screw-rod fixations (CSR or PSR), TLIF had a significantly larger normalized ROM than LLIF in all directions at both proximal and distal adjacent segments (p ≤ 0.04). CONCLUSIONS The use of PSR versus CSR during single-level lumbar fusion can significantly affect mobility at the adjacent segment, regardless of the presence of TLIF or with either TLIF or LLIF. Moreover, the type of interbody support also had a significant effect on adjacent-segment mobility.

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