Morphologic Consideration of C2 Isthmus for Placement of Transarticular Screws Using Human Cadaveric Vertebrae.
Yoshihiro RyokiKosei IjiriNoboru TaniguchiTakashi MotobeTakeshi TakenouchiMotoyuki TanakaMasahiko AbematsuSetsuro KomiyaEiji TaketomiNobuhiko SunaharaKazuyuki Shimada
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Abstract:
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.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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Teraoka, Satoshi1,2; Nomoto, Kikuo2,3; Mito, Michio2; Yoshinaga, Kaoru2; Kurikawa, Kiyoshi2,4; Igata, Akihiro2; Sonoda, Takao2; Fujimi, Satoru2 Author Information
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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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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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There is a paucity of literature documenting the cadaveric muscle thickness of pronator quadratus. We measured the width and depth of this muscle bilaterally in 15 cadavers. There was a significant difference in thickness between male and female cadavers, but the width was proportional to radius length.
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Synthetic polyurethane foams are frequently used in biomechanical testing of spinal medical devices. However, it is unclear what types of foam are most representative of human vertebral trabecular bone behavior, particularly for testing the bone-implant interface. Therefore, a study was conducted to compare polyurethane foam microstructure and screw pullout properties to human vertebrae. Cadaveric thoracolumbar vertebrae underwent microcomputed tomography to assess trabecular bone microstructure. Spine plate screws were implanted into the vertebral body and pullout testing was performed. The same procedure was followed for eight different densities (grades 5-30) of commercially available closed cell (CCF) and open cell foams (OCF). The results indicated that foam microstructural parameters such as volume fraction, strut thickness, strut spacing, and material density rarely matched that of trabecular bone. However, certain foams provided mechanical properties that were comparable to the cadavers tested. Pullout force and work to pullout for screws implanted into CCF grade 5 were similar to osteoporotic female cadavers. In addition, screw pullout forces and work to pullout in CCF grade 8, grade 10, and OCF grade 30 were similar to osteopenic male cadavers. All other OCF and CCF foams possessed pullout properties that were either significantly lower or higher than the cadavers tested. This study elucidated the types and densities of polyurethane foams that can represent screw pullout strength in human vertebral bone. Synthetic bone surrogates used for biomechanical testing should be selected based on bone quantity and quality of patients who may undergo device implantation.
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To verify the articular branch contributions in the human knee, delineate their anatomical variance, and outline the limitations of currently applied procedure protocols for denervation of the knee joint.A detailed anatomical dissection.Cadavers in residence at the Albert Einstein College of Medicine.In total, 24 lower extremity specimens from 14 embalmed cadavers.Human cadaveric dissections were performed on 24 lower extremities from 14 embalmed cadavers.This cadaveric study has demonstrated that the anterior knee receives sensory innervations from SMGN, SLGN, LRN, NVI, NVL, RFN, and IMGN. The courses of SMGN, SLGN, RFN, and IMGN are similar to recent anatomical studies. However, discrepancies exist in their relative anatomy to bony and radiographic landmarks.Genicular denervation using classical anatomical landmarks may not be sufficient to treat the anterior knee joint pain. Our findings illustrate more accurate anatomic landmarks for the three-target paradigm and support additional targets for more complete genicular denervation. This cadaveric study provides robust anatomical findings that can provide a foundation for new anatomical landmarks and targets to improve genicular denervation outcomes.
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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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