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Biomechanics of the goat three bundle anterior cruciate ligament
No full textIntroduction: The goat is a widely used animal model for basic research on the anterior cruciate ligament (ACL), but the biomechanical role of the different bundles [intermediate (IM), anteromedial (AM), posterolateral (PL)] of the ACL is unclear. Therefore, the aim of this study is to describe the biomechanical function of the different bundles and evaluate its use for a double bundle ACL reconstruction model.
Materials and Methods: A CASPAR Stäubli RX90 robot with a six degree-of-freedom load cell was used for measurement of anterior tibial translation (ATT) (mm) and in situ forces (N) at 30° (full extension), 60°, 90° as well as rotational testing at 30° in 14 paired goat knees before and after each bundle was cut.
Results: When the AM-bundle was cut, the ATT increased significantly at 60° and 90° of flexion (p<0.05). When the PL-bundle was cut, the ATT increased only at 30°. However, most load was transferred through the big AM-bundle while the PL-bundle shared significant load only at 30°, with only minimal contribution from the IM-bundle at all flexion degrees.
Discussion: The observed biomechanical results in this study are similar to the human ACL observed previously in the literature. Though anatomically discernible, the IM-bundle plays only an inferior role in ATT and might be neglected as a separate bundle during reconstruction.
Conclusions: The goat ACL shows some differences to the human ACL, whereas the main functions of the ACL bundles are similar
Anatomical description of the anterior cruciate ligament in the goat knee.
No full textPURPOSE
The goat knee has been widely used for anterior cruciate ligament (ACL) reconstruction models, including biomechanical and biological studies. The purpose of this study was to perform a detailed qualitatively and quantitatively assessment of the ACL, its bundles and its insertion site in the goat knee.
METHODS
Ten fresh-frozen non-paired adult goat knees were used in this study. We measured the insertion site area of each bundle, the distances between the center of these areas and the anatomy landmarks. Moreover, we analyzed the ratio between the femoral and tibial insertion site areas and the midsubstance cross-sectional area of the ACL. A digitizing systems, Microscribe 3D and 3D-laser camera, were used to record the data. Statistical analysis was performed using a t test with p < 0.05 being considered statistically significant.
RESULTS
Three bundles could be clearly identified in each ACL: anteromedial (AM), intermediate (IM) and posterolateral (PL) bundle (Fig. 1). Interestingly, the anterior horn attachment of the lateral meniscus (* in Fig.1) divides the anterior portion of the tibial ACL insertion into AM and IM/PL bundles. On the tibial side, the insertion of the IM and PL bundles could not be identified separately.
On the femur, the area of insertion site, represented as a percentage of the entire footprint, was 54.3 ± 7.8% for AM, 9.9 ± 3.8% for IM and 35.8 ± 4.4% for PL bundle. The area of tibial insertion was 68.6 ± 4.7% for AM and 31.4 ± 4.7% for IM/PL bundle. The differences between the entire femoral (51.9 ± 4.6 mm2) and tibial (81.1 ± 11.9 mm2) footprint areas and between each bundle were statistical significant (p < 0.05).
All insertions had significantly larger areas than the ligament midsubstance cross-sectional area (21.76 ± 7.26 mm2) (p < 0.05).
CONCLUSION
The precise knowledge of the ACL anatomy in the goat knee is necessary when a goat model is planned. Our study provides valuable information about the ACL, its bundles and its femoral and tibial insertion sites. Although it shares some similarities with the human ACL, the goat has some specific features that must be considered. Further investigation should be conducted in order to determine the biomechanical role of each bundle in the goat knee
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Anatomical description and quantitative analysis of the anterior cruciate ligament of the goat knee.
No full textPurpose
The goat knee has been widely used for anterior cruciate ligament (ACL) reconstruction models, including biomechanical and biological studies. The purpose of this study was to perform a detailed qualitatively and quantitatively assessment of the ACL, its bundles and its insertion site in the goat knee.
Materials and Methods
Ten fresh-frozen non-paired adult goat knees were used in this study. We measured the insertion site area of each bundle, the distances between the center of these areas and the anatomy landmarks. Moreover, we analyzed the ratio between the femoral and tibial insertion site areas and the midsubstance cross-sectional area of the ACL. A digitizing systems, Microscribe 3D and 3D-laser camera, were used to record the data. Statistical analysis was performed using a t test with p < 0.05 being considered statistically significant.
Results
Three bundles could be clearly identified in each ACL: anteromedial (AM), intermediate (IM) and posterolateral (PL) bundle. Interestingly, the anterior horn attachment of the lateral meniscus divides the anterior portion of the tibial ACL insertion into AM and IM/PL bundles. On the tibial side, the insertion of the IM and PL bundles could not be identified separately. On the femoral side, each insertion were clearly identified separately.
On the femur, the area of insertion site, represented as a percentage of the entire footprint, was 54.3 ± 7.8% for AM, 9.9 ± 3.8% for IM and 35.8 ± 4.4% for PL bundle. The area of tibial insertion was 68.6 ± 4.7% for AM and 31.4 ± 4.7% for IM/PL bundle. The differences between the entire femoral (51.9 ± 4.6 mm2) and tibial (81.1 ± 11.9 mm2) footprint areas and between each bundle were statistical significant (p < 0.05).
All insertions had significantly larger areas than the ligament midsubstance cross-sectional area (21.76 ± 7.26 mm2) (p < 0.05).
Conclusion
The precise knowledge of the ACL anatomy in the goat knee is necessary when a goat model is planned. Our study provides valuable information about the ACL, its bundles and its femoral and tibial insertion sites. Although it shares some similarities with the human ACL, the goat has some specific features that must be considered. Further investigation should be conducted in order to determine the biomechanical role of each bundle in the goat knee
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Biomechanics of the goat three bundle anterior cruciate ligament
No full textThe goat is a widely used animal model for basic research on the anterior cruciate ligament (ACL), but the biomechanical role of the different bundles [intermediate (IM), anteromedial (AM), posterolateral (PL)] of the ACL is unclear. Therefore, the aim of this study is to describe the biomechanical function of the different bundles and evaluate its use for a double bundle ACL reconstruction model. A CASPAR Stäubli RX90 robot with a six degree-of-freedom load cell was used for measurement of anterior tibial translation (ATT) (mm) and in situ forces (N) at 30 degrees (full extension), 60 degrees , 90 degrees as well as rotational testing at 30 degrees in 14 paired goat knees before and after each bundle was cut. When the AM-bundle was cut, the ATT increased significantly at 60 degrees and 90 degrees of flexion (p < 0.05). When the PL-bundle was cut, the ATT increased only at 30 degrees. However, most load was transferred through the big AM-bundle while the PL-bundle shared significant load only at 30 degrees, with only minimal contribution from the IM-bundle at all flexion degrees. The observed biomechanical results in this study are similar to the human ACL observed previously in the literature. Though anatomically discernible, the IM-bundle plays only an inferior role in ATT and might be neglected as a separate bundle during reconstruction. The goat ACL shows some differences to the human ACL, whereas the main functions of the ACL bundles are similar
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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