Pullout Strength after Expandable Polymethylmethacrylate Transpedicular Screw Augmentation for Pedicle Screw Loosening
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Pedicle screw fixation for spine arthrodesis is a useful procedure for the treatment of spinal disorders. However, instrument failure often occurs, and pedicle screw loosening is the initial step of a range of complications. The authors recently used a modified transpedicular polymethylmethacrylate (PMMA) screw augmentation technique to overcome pedicle screw loosening. Here, they report on the laboratory testing of pedicle screws inserted using this modified technique.To evaluate pullout strengths three cadaveric spinal columns were used. Three pedicle screw insertion methods were utilized to compare pullout strength; the three methods used were; control (C), traditional transpedicular PMMA augmentation technique (T), and the modified transpedicular augmentation technique (M). After control screws had been pulled out, loosening with instrument was made. Screw augmentations were executed and screw pullout strength was rechecked.Pedicle screws augmented using the modified technique for pedicle screw loosening had higher pullout strengths than the control (1106.2±458.0 N vs. 741.2±269.5 N; p=0.001). Traditional transpedicular augmentation achieved a mean pullout strength similar to that of the control group (657.5±172.3 N vs. 724.5±234.4 N; p=0.537). The modified technique had higher strength than the traditional PMMA augmentation technique (1070.8±358.6 N vs. 652.2±185.5 N; p=0.023).The modified PMMA transpedicular screw augmentation technique is a straightforward, effective surgical procedure for treating pedicle screw loosening, and exhibits greater pullout strength than traditional PMMA transpedicular augmentation. However, long-term clinical evaluation is required.Keywords:
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One hundred twelve fresh cadaveric spines were harvested using a newly described technique.To develop and describe a technique for the expeditious excision of intact human cadaveric spines for biomechanical testing, to educate the dissector on the health and safety issues involved in harvesting spinal specimens, and to review the present recommendations for storage and preservation of spinal segments.As the need for biomechanical spinal research continues to expand, the demand for fresh human cadaveric vertebral specimens increases. Previous techniques for harvesting are simplistic and sparse. This technique offers a reliable and expeditious method for procurement of spinal vertebral segments of any size.Human cadaveric spines were harvested using an adaptation of previous posterior spinal approaches. Techniques for sectioning each vertebral region were developed. Detailed description of these techniques was meticulously documented. The procured spinal segments have been used for multiple biomechanical investigations.The technique has been used successfully in more than 100 spinal harvests. Approximate time required is 30 minutes. The harvested segments have been reliable biomechanical specimens in many published studies.A new technique for the rapid extraction of human cadaveric spines has been developed. Dissectors may benefit from the recommendations offered for sectioning of each region.
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Background: We hypothesized that using a cadaveric Lisfranc ligamentous injury model, abduction stress would provoke greater post-injury motion than axial weightbearing between the medial cuneiform (MC1) and the base of the second metatarsal (MT2). Second, we hypothesized that both a tensioned suture-button device and a rigid screw fixation method could maintain a reduction and similarly restrain motion to intact (pre-injury) levels. Materials and Methods: Motion was measured between MC1 and MT2 in five matched pairs of human cadaveric feet. Specimens were tested prior to injury, following a transverse ligamentous Lisfranc injury, and then randomized to either screw or tensioned suture-button fixation. Axial then abduction loads were applied. Measurements were repeated after one thousand loading cycles. Results: With both axial and abduction loads, statistically significant differences in motion were detected between the intact and post-injury conditions, although the magnitudes were greater with abduction (6.8 mm versus 2.0 mm, p = 0.000004). With abduction loads, both fixation methods were effective in restraining motion to pre-injury levels (screw fixation: 1.5 mm intact versus 1.1 mm post-fixation, p = 0.487; suture-button fixation: 1.3 mm intact versus 2.1 mm post-fixation, p = 0.063), and similarly, both devices restrained motion to less than post-injury levels (screw fixation: 8.1 mm post-injury versus 1.1 mm post-fixation, p = 0.001; suture-button fixation: mean 5.5 mm post-injury versus 2.1 mm post-fixation, p = 0.0002). No significant differences in these patterns were detected following cyclic loading. Conclusion: Small, though statistically significant, amounts of motion are produced between MC1 and MT2 with axial loading after a ligamentous Lisfranc injury. With abduction stress, we were able to show a significantly greater difference between pre- and post-injury motion and the ability of both fixation methods to restrain motion to pre-injury levels. Clinical Relevance: Abduction stress may be valuable when diagnosing and testing the transverse ligamentous Lisfranc injury. Both suture-button and screw fixation methods restrain motion at the Lisfranc complex.
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Abstract Background: Cadaveric research has widely influenced our understanding of clinical anatomy. However, while many soft‐tissue structures remain quiescent after death, other tissues, such as viscera, undergo structural and functional changes that may influence their use in predicting living anatomy. In particular, our understanding of vascular anatomy has been based upon cadaveric studies, in which vascular tone and flow do not match the living situation. Methods: An angiographic analysis of the abdominal wall vasculature was performed using plain film and computed tomography angiography in 60 cadaveric hemi‐abdominal walls (from 31 cadavers) and 140 living hemi‐abdominal walls (in 70 patients). The deep inferior epigastric artery (DIEA) and all of its perforating branches larger than 0.5 mm were analysed for number, calibre and location. Results: Both large, named vessels and small calibre vessels show marked differences between living anatomy and cadaveric specimens. The DIEA was of larger diameter (4.2 mm versus 3.1 mm, P < 0.01) and had more detectable branches in the cadaveric specimens. Perforators were of greater calibre (diameter 1.5 mm versus 0.8 mm, P < 0.01) and were more plentiful (16 versus 6, P < 0.01) in cadaveric specimens. However, the location of individual vessels was similar. Conclusions: Cadaveric anatomy displays marked differences to in vivo anatomy, with the absence of living vascular dynamics affecting vessel diameters in cadaveric specimens. Blood vessels are of greater measurable calibre in cadaveric specimens than in the living. Consequently, cadaveric anatomy should be interpreted with consideration of post‐mortem changes, while living anatomical studies, particularly with the use of imaging technologies, should be embraced in anatomical research.
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Study of the preservation of baitan and baileton in cadaveric material revealed that baitan was partially transformed in baileton in cadaveric liver. The content of the studied compounds in cadaveric liver upon storage of different duration has been assessed.
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Background: Cadaveric research has widely influenced our understanding of clinical anatomy. However, while many soft-tissue structures remain quiescent after death, other tissues undergo structural and functional changes that may influence their use in predicting living anatomy. In particular, our understanding of vascular anatomy has been based upon cadaveric studies in which vascular tone and flow do not match the living situation. Methods: An angiographic analysis of the abdominal wall vasculature was performed using plain-film and computed tomography (CT) angiography in 60 cadaveric and 140 living (70 patients) hemi-abdominal walls The deep inferior epigastric artery (DIEA) and all of its perforating branches larger than 0.5 mm were analysed for number, calibre and location. Results: Both large, named vessels and small calibre vessels show marked differences between living anatomy and cadaveric specimens. The DIEA was of larger diameter (4.2 mm vs. 3.1 mm, p < 0.01) and had more detectable branches in the cadaveric specimens. Perforators were of greater calibre (diameter 1.5 mm vs. 0.8 mm, p < 0.01) and were more plentiful (16 vs. 6, p < 0.01) in cadaveric specimens. However, the location of individual vessels was similar. Conclusions: Cadaveric anatomy displays marked differences to in-vivo anatomy, with the absence of living vascular dynamics affecting vessel diameters in cadaveric specimens. Blood vessels are of greater measurable calibre in cadaveric specimens than in the living. Consequently, cadaveric anatomy should be interpreted with consideration of post-mortem changes, while living anatomical studies, particularly with the use of imaging technologies, should be embraced in anatomical research.
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SUMMARY The light and electron microscope appearances of biopsies from five cadaveric renal homotransplants taken at the end of the operation and one post–operative biopsy are described. Reference is also made to other cadaveric homotransplants and to three autotransplanted dog kidneys. The appearance of the operative biopsies has given some guide to the subsequent function of the cadaveric transplants.
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We investigated the morphology of the C2 isthmus for the placement of transarticular screws using human cadaveric vertebrae and 3D-CT, for safe screwing of C1-2 fixation in an identical manner to the Magerl technique. We measured the width of the C2 isthmus, optimum screw insertion angle, and optimum length of the screw.There were significant differences in the measured values among the cadaveric vertebrae and each side (right and left). The measured values of human cadaveric vertebrae correlated precisely with those of 3D-CT. The safe screw passage area between spinal canal and vertebral artery is severely limitted.The Magerl technique is commonly performed under anteroposterior and lateral view images. Some have pointed out that this technique is difficult because it requires a high degree of skill. These results demonstrate that preoperatively reconstructed 3D-CT is relatively valuable for safe screw fixation by the Magerl technique.
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Objectives: There is limited cadaveric data regarding the feasibility of pedicled nasoseptal flap (PNSF) for anterior skull base (ABS) reconstruction. The purpose of this study is to assess the feasibility of PNSF for ASB reconstruction and to describe a method to compensate the shortage of flap length using a cadaveric model.
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