A computational analysis of locomotor anatomy and body mass evolution in Allosauroidea (Dinosauria: Theropoda)

Paleobiology ◽  
2012 ◽  
Vol 38 (3) ◽  
pp. 486-507 ◽  
Author(s):  
Karl T. Bates ◽  
Roger B. J. Benson ◽  
Peter L. Falkingham
Keyword(s):  
Body Size ◽  
Soft Tissue ◽  
Center Of Mass ◽  
Soft Tissue Reconstruction ◽  
Locomotor Performance ◽  
Body Proportions ◽  
Data Set ◽  
Positive Allometry ◽  
Moment Arms ◽  
Musculoskeletal Anatomy

We investigate whether musculoskeletal anatomy and three-dimensional (3-D) body proportions were modified during the evolution of large (>6000 kg) body size in Allosauroidea (Dinosauria: Theropoda). Three adaptations for maintaining locomotor performance at large body size, related to muscle leverage, mass, and body proportions, are tested and all are unsupported in this analysis. Predictions from 3-D musculoskeletal models of medium-sized (Allosaurus) and large-bodied (Acrocanthosaurus) allosauroids suggest that muscle leverage scaled close to isometry, well below the positive allometry required to compensate for declining muscle cross-sectional area with increasing body size. Regression analyses on a larger allosauroid data set finds slight positive allometry in the moment arms of major hip extensors, but isometry is included within confidence limits. Contrary to other recent studies of large-bodied theropod clades, we found no compelling evidence for significant positive allometry in muscle mass between exemplar medium- and large-bodied allosauroids. Indeed, despite the uncertainty in quantitative soft tissue reconstruction, we find strong evidence for negative allometry in the caudofemoralis longus muscle, the single largest hip extensor in non-avian theropods. Finally, we found significant inter-study variability in center-of-mass predictions for allosauroids, but overall observe that consistently proportioned soft tissue reconstructions produced similar predictions across the group, providing no support for a caudal shift in the center of mass in larger taxa that might otherwise reduce demands on hip extensor muscles during stance. Our data set provides further quantitative support to studies that argue for a significant decline in locomotor performance with increasing body size in non-avian theropods. However, although key pelvic limb synapomorphies of derived allosauroids (e.g., dorsomedially inclined femoral head) evolved at intermediate body sizes, they may nonetheless have improved mass support.

Reoperation Profile of Lateral vs Anterior Approach Ankle Arthroplasty

2020 ◽  
Vol 41 (7) ◽  
pp. 834-838
Author(s):  
Oliver J. Gagné ◽  
Murray Penner ◽  
Kevin Wing ◽  
Andrea Veljkovic ◽  
Alastair S. Younger
Keyword(s):  
Soft Tissue ◽  
Anterior Approach ◽  
Lateral Approach ◽  
Wound Complications ◽  
Soft Tissue Reconstruction ◽  
Foot And Ankle ◽  
Data Set ◽  
Ankle Arthroplasty ◽  
Lateral Group ◽  
Anterior Group

Background: The operative procedure for a total ankle replacement (TAR) is intimately associated with the prosthetic design. The anterior and lateral approaches both have pros and cons regarding their respective soft tissue complications, osteotomy requirements, orientation of the bone cut, and gutter visualization. Although both have been studied independently, few reports have compared both in the same setting. The purpose of this retrospective study was to investigate the difference in reoperation rate after lateral or anterior approach ankle arthroplasty. We hypothesized that the anterior approach had a higher rate of wound complications. Methods: We evaluated data from a single center collected between 2014 and 2017, comprising a total of 115 total ankle replacements performed by 1 of 4 fellowship-trained foot and ankle surgeons. Reoperations were recorded as an operative report with classification by Canadian Orthopaedic Foot and Ankle Society (COFAS) Reoperations Coding System (CROCS). The index approach used was determined by the surgeon’s practice preference. Patients were included when they had a primary TAR in the time frame noted and had a complete data set up to at least 2 years after surgery. The cohort comprised 67 anterior and 48 lateral operations with balanced demographics for age (95% CI: 63-67 years) and gender (47% F). The lateral group had more complex cases with higher COFAS type arthritis (more periarticular arthritis and surrounding deformity). Results: Comparing the 2 groups, a total of 40 reoperations (7 anterior [A], 33 lateral [L]) occurred in 27 patients (5 A, 22 L). One patient had 4 related reoperations. The only revision was in the anterior group. The only soft tissue reconstruction was a split-thickness skin graft in the lateral group. Nine reoperations were irrigation debridement related to an infection or wound complication (3 A, 6 L). The majority (19/33) of reoperations in the lateral group were gutter debridement (8) or lateral hardware removal (11). Operative time was statistically different at 145 minutes (95% CI: 127-164 minutes) in anterior TAR and 178 minutes (95% CI: 154-202 minutes) for lateral TAR ( P = .0058). The odds ratio of having any reoperation with a lateral approach TAR was 6.19 compared to the anterior group. Conclusion: The results at the 2-year time point demonstrated that there were more reoperations after a lateral approach TAR than an anterior TAR, recognizing the significant case complexity imbalance between the groups and a corresponding relative increase in resource utilization of lateral TAR patients. The 2 implant designs were associated with different reoperation rates, favoring the anterior group. Change in the lateral fixation may have reduced the risk of repeat surgery. Level of Evidence: Level III, retrospective comparative series.

Autologous Fat Transfer and Cell-Based Strategies for Soft Tissue Reconstruction

2014 ◽  
Vol 3 (1) ◽  
pp. 62-69
Author(s):  
Kshemendra Senarath-Yapa ◽  
Rebecca Garza ◽  
Adrian McArdle ◽  
Graham Walmsley ◽  
Michael Hu ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Soft Tissue Reconstruction ◽  
Fat Transfer ◽  
Autologous Fat ◽  
Autologous Fat Transfer ◽  
Tissue Reconstruction

Allometry and Paleoecology of Medial Miocene Dwarf Rhinoceroses from the Texas Gulf Coastal Plain

Paleobiology ◽  
1982 ◽  
Vol 8 (1) ◽  
pp. 16-30 ◽  
Author(s):  
Donald R. Prothero ◽  
Paul C. Sereno
Keyword(s):  
Body Size ◽  
Coastal Plain ◽  
Sympatric Species ◽  
High Plains ◽  
Gulf Coastal Plain ◽  
Canine Tooth ◽  
Positive Allometry ◽  
Mammalian Faunas ◽  
The Common ◽  
Limb Proportions

Barstovian (medial Miocene) mammalian faunas from the Texas Gulf Coastal Plain contained four apparently sympatric species of rhinoceroses: the common forms Aphelops megalodus and Teleoceras medicornutus, a dwarf Teleoceras, and a dwarf Peraceras. Previous work has suggested positive allometry in tooth area with respect to body size in several groups of mammals, i.e., larger mammals have relatively more tooth area. However, dwarfing lineages were shown to have relatively more tooth area for their body size. Our data show no significant allometry in post-canine tooth area of either artiodactyls or ceratomorphs. Similarly, dwarf rhinoceroses and hippopotami show no more tooth area than would be predicted for their size. Limbs are proportionately longer and more robust in larger living ceratomorphs (rhinos and tapirs) than predicted by previous authors. Limb proportions of both dwarf rhinoceroses and dwarf hippopotami are even more robust than in their living relatives.The high rhinoceros diversity reflects the overall high diversity of Barstovian faunas from the Texas Gulf Coastal Plain. The first appearance of several High Plains mammals in these faunas indicates “ecotone”-like conditions as faunal composition changed. Study of living continental dwarfs shows that there is commonly an ecological separation between browsing forest dwarfs and their larger forebears, which are frequently savannah grazers. This suggests that the dwarf rhinoceroses might have been forest browsers which were sympatric with the larger grazing rhinos of the High Plains during the Barstovian invasion. The continental dwarf model also suggests that insular dwarfism may be explained by the browsing food resources that predominate on islands.

scholarly journals Radical treatment of severe open fractures of extremities by orthoplastic surgery: a 10-year retrospective study

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Zhao Yang ◽  
Chao Xu ◽  
Yong-Gang Zhu ◽  
Jun Li ◽  
Zi-Xiang Wu ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Infection Rate ◽  
Clinical Data ◽  
Open Fractures ◽  
Soft Tissue Reconstruction ◽  
Satisfactory Outcome ◽  
Tissue Damages ◽  
Tissue Reconstruction ◽  
Severe Soft Tissue

Abstract Objective This study aimed to retrospectively analyze clinical data of a series of patients with severe open fractures of extremities (Gustilo IIIb or IIIc), who achieved a satisfactory outcome through radical orthoplastic surgery, so as to provide a reference for determining the treatment of severe open fractures of extremities. Methods The clinical data of 41 consecutive patients with severe open fracture (Gustilo IIIb or IIIc) of the limb, who underwent successful surgical debridement, fixation, and soft tissue reconstruction in one stage between January 2008 and January 2019, were retrospectively reviewed. Postoperative indicators, including infection rate and union time, were acquired by a regular follow-up and analyzed. Results The mean (±SD) age of the patients was 38 ± 16 years. A total of 90 open fractures and severe soft tissue damages were analyzed. The soft tissue cover was achieved within 72 h. The overall rate of infection was 14.6% (6/41). Sex and the Mangled Extremity Severity Score were associated with infection. The median union time of 40 patients (one amputation) was 32 weeks. Conclusion The overall rate of infection exhibited a lower tendency in this study compared with previous studies on high-grade open fractures following a two-stage orthopedic approach. The consequence of infection rate and union time was similar to that in previous studies. These results indicated that the single-stage radical orthoplastic treatment was an effective and reliable option for reconstructing severe open fractures.

scholarly journals Micro-CT imaging of Thiel-embalmed and iodine-stained human temporal bone for 3D modeling

2021 ◽  
Vol 50 (1) ◽  
Author(s):  
Sebastian Halm ◽  
David Haberthür ◽  
Elisabeth Eppler ◽  
Valentin Djonov ◽  
Andreas Arnold
Keyword(s):  
Soft Tissue ◽  
Temporal Bone ◽  
Middle Ear ◽  
3D Modeling ◽  
Soft Tissues ◽  
Ct Imaging ◽  
Micro Ct ◽  
Data Set ◽  
Iodine Staining ◽  
Tissue Structures

Abstract Introduction This pilot study explores whether a human Thiel-embalmed temporal bone is suitable for generating an accurate and complete data set with micro-computed tomography (micro-CT) and whether solid iodine-staining improves visualization and facilitates segmentation of middle ear structures. Methods A temporal bone was used to verify the accuracy of the imaging by first digitally measuring the stapes on the tomography images and then physically under the microscope after removal from the temporal bone. All measurements were compared with literature values. The contralateral temporal bone was used to evaluate segmentation and three-dimensional (3D) modeling after iodine staining and micro-CT scanning. Results The digital and physical stapes measurements differed by 0.01–0.17 mm or 1–19%, respectively, but correlated well with the literature values. Soft tissue structures were visible in the unstained scan. However, iodine staining increased the contrast-to-noise ratio by a factor of 3.7 on average. The 3D model depicts all ossicles and soft tissue structures in detail, including the chorda tympani, which was not visible in the unstained scan. Conclusions Micro-CT imaging of a Thiel-embalmed temporal bone accurately represented the entire anatomy. Iodine staining considerably increased the contrast of soft tissues, simplified segmentation and enabled detailed 3D modeling of the middle ear.

Nanofiber-hydrogel composite–mediated angiogenesis for soft tissue reconstruction

2019 ◽  
Vol 11 (490) ◽  
pp. eaau6210 ◽  
Author(s):  
Xiaowei Li ◽  
Brian Cho ◽  
Russell Martin ◽  
Michelle Seu ◽  
Chi Zhang ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Donor Site ◽  
Rabbit Model ◽  
Soft Tissue Defect ◽  
Fat Grafting ◽  
Foreign Body Response ◽  
Soft Tissue Reconstruction ◽  
Hydrogel Composite ◽  
Tissue Flaps ◽  
Tissue Restoration

Soft tissue losses from tumor removal, trauma, aging, and congenital malformation affect millions of people each year. Existing options for soft tissue restoration have several drawbacks: Surgical options such as the use of autologous tissue flaps lead to donor site defects, prosthetic implants are prone to foreign body response leading to fibrosis, and fat grafting and dermal fillers are limited to small-volume defects and only provide transient volume restoration. In addition, large-volume fat grafting and other tissue-engineering attempts are hampered by poor vascular ingrowth. Currently, there are no off-the-shelf materials that can fill the volume lost in soft tissue defects while promoting early angiogenesis. Here, we report a nanofiber-hydrogel composite that addresses these issues. By incorporating interfacial bonding between electrospun poly(ε-caprolactone) fibers and a hyaluronic acid hydrogel network, we generated a composite that mimics the microarchitecture and mechanical properties of soft tissue extracellular matrix. Upon subcutaneous injection in a rat model, this composite permitted infiltration of host macrophages and conditioned them into the pro-regenerative phenotype. By secreting pro-angiogenic cytokines and growth factors, these polarized macrophages enabled gradual remodeling and replacement of the composite with vascularized soft tissue. Such host cell infiltration and angiogenesis were also observed in a rabbit model for repairing a soft tissue defect filled with the composite. This injectable nanofiber-hydrogel composite augments native tissue regenerative responses, thus enabling durable soft tissue restoration outcomes.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

Soft-Tissue Reconstruction of External Hemipelvectomy Defects

2009 ◽  
Vol 124 (1) ◽  
pp. 144-155 ◽  
Author(s):  
Alex Senchenkov ◽  
Steven L. Moran ◽  
Paul M. Petty ◽  
James Knoetgen ◽  
Nho V. Tran ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Soft Tissue Reconstruction ◽  
Tissue Reconstruction
Sign in / Sign up

Export Citation Format

Share Document