Forelimb posture in neoceratopsian dinosaurs: implications for gait and locomotion

Paleobiology ◽  
2000 ◽  
Vol 26 (3) ◽  
pp. 450-465 ◽  
Author(s):  
Gregory S. Paul ◽  
Per Christiansen
Keyword(s):  
Alternative View ◽  
Running Speed ◽  
High Speeds ◽  
Articular Surfaces ◽  
Parasagittal Plane ◽  
Sprawling Posture ◽  
Femoral Condyles

Ceratopsid dinosaurs traditionally have been restored with sprawling forelimbs and were considered unable to run at high speeds. An alternative view restores the ceratopsids as rhinoceros-like with parasagittal forelimb kinematics and the ability to run faster than extant elephants. Several anatomical difficulties concerning the mounting of ceratopsid skeletons with nearly parasagittal forelimbs stem not from the forelimb itself, but from errors in rib and vertebral articulation. Matching a skeletal restoration to a probable ceratopsid trackway shows that the hands were placed directly beneath the glenoids, and that manual impressions were directed laterally, not medially as in sprawling reptiles. Pedal impressions in trackways are medial to the manual impressions, owing to the slightly averted elbow and to the asymmetrical distal femoral condyles, which directed the crus slightly medially. The limbs of ceratopsians of all sizes display substantial joint flexure, strongly indicating that the elephantine forelimb posture that has sometimes been suggested as the alternative to a sprawling posture is erroneous. The articular surfaces of uncrushed ceratopsian scapulocoracoids and forelimb joints confirm that the forelimb operated in a near-parasagittal plane with the elbows only slightly averted. The maximal running speed of even the largest ceratopsids is inferred to have significantly exceeded that of elephants and was probably broadly similar to that of rhinos.

Locomotion in Burrowing and Vagrant Wolf Spiders (Lycosidae)

1981 ◽  
Vol 92 (1) ◽  
pp. 305-321 ◽  
Author(s):  
T. M. WARD ◽  
W. F. HUMPHREYS
Keyword(s):  
Wolf Spider ◽  
The Body ◽  
Power Stroke ◽  
Phase Lag ◽  
Running Speed ◽  
Wolf Spiders ◽  
High Speeds ◽  
Phase Lags ◽  
The Relationship

Locomotion in the vagrant wolf spider Trochosa ruricola is compared to that in the burrow dwelling wolf spider Lycosa tarentula (Araneae: Lycosidae). L. tarentula takes relatively shorter steps than T. ruricola. At high speeds T. ruricola approximates an alternating tetrapod gait but this does not occur in L. tarentula. Phase lag differs between species and varies marginally with speed except for ipsilateral phase lags in L. tarentula which are erratic if they include leg 1. In both species the protraction/retraction ratio is directly related to both running speed and stepping frequency, but the relationship is more marked in L. tarentula. The protraction/retraction ratio is more variable in leg 1 and varies between legs along the body but by a greater amount in L. tarentula. In these spiders, in contrast to the situation in many insects, both the duration of protraction and retraction show marked inverse relationships to stepping frequency. The power stroke (retraction) occupies a variable proportion of the stepping cycle, which is not the case in other spiders, and this proportion is lower than for other spiders. It is suggested that the first pair of legs is used more for sensory than for locomotory purpose and that this is more marked in the burrow dwelling species, L. tarentula.

Computerized Matching of Autologous Femoral Grafts for the Treatment of Medial Talar Osteochondral Defects

2005 ◽  
Vol 26 (9) ◽  
pp. 708-712 ◽  
Author(s):  
John V. Marymont ◽  
Gerald Shute ◽  
Hongseng Zhu ◽  
Kevin E. Varner ◽  
Vibor Paravic ◽  
...  
Keyword(s):  
Distal Femur ◽  
Donor Site ◽  
Computer Software ◽  
Optimal Location ◽  
Osteochondral Graft ◽  
Osteochondral Defects ◽  
Potential Donor ◽  
Articular Surfaces ◽  
Surface Contour ◽  
Femoral Condyles

Background: Cored autologous graft from the distal ipsilateral femur has been used to fill osteochondral defects in the talus. There are no studies that compare the articular morphology of potential donor sites on the distal femur with recipient sites on the talus. Methods: Using coronal MRI of the talus and distal femur of five matched cadaver, computer reconstructions of the articular surfaces were prepared. From these, six 10-mm in diameter donor sites from the nonweightbearing surfaces of the medial and lateral aspects of the femoral condyles were matched to three recipient sites on the anterior, middle, and posterior aspects of the corresponding medial talus using customized computer software that minimized differences between the articular surfaces of the graft and the talus. After matching the femoral to the talar graft, the average and maximal distances between the surfaces (surface contour) and the average and maximal distances of the offset at the outer 1 mm of the graft periphery (step-off) were determined. Results: For all graft combinations, the average step-off was 0.24 +/−0.03 mm and the maximum 0.60 mm. The average surface contour was 0.32 +/−0.04 mm and the maximum was 1.16 mm. In all cases, the best donor site was from the superolateral femur for any medial talar lesion. Conclusion: In this study of grafts from the femoral condyles, the superolateral femur was the optimal location for an osteochondral graft for any medial talar lesion.

scholarly journals How moles walk; it's all thumbs

2019 ◽  
Vol 15 (10) ◽  
pp. 20190503 ◽  
Author(s):  
Yi-Fen Lin ◽  
Nicolai Konow ◽  
Elizabeth R. Dumont
Keyword(s):  
Horizontal Plane ◽  
Stance Phase ◽  
The Body ◽  
Joint Mobility ◽  
Sesamoid Bone ◽  
Erect Posture ◽  
X Ray ◽  
Parasagittal Plane ◽  
Limb Posture ◽  
Sprawling Posture

A recurring theme in the evolution of tetrapods is the shift from sprawling posture with laterally orientated limbs to erect posture with the limbs extending below the body. However, in order to invade particular locomotor niches, some tetrapods secondarily evolved a sprawled posture. This includes moles, some of the most specialized digging tetrapods. Although their forelimb anatomy and posture facilitates burrowing, moles also walk long distances to forage for and transport food. Here, we use X-ray Reconstruction Of Moving Morphology (XROMM) to determine if the mole humerus rotates around its long axis during walking, as it does when moles burrow and echidnas walk, or alternatively protracts and retracts at the shoulder in the horizontal plane as seen in sprawling reptiles. Our results reject both hypotheses and demonstrate that forelimb kinematics during mole walking are unusual among those described for tetrapods. The humerus is retracted and protracted in the parasagittal plane above, rather than below the shoulder joint and the ‘false thumb’, a sesamoid bone (os falciforme), supports body weight during the stance phase, which is relatively short. Our findings broaden our understanding of the diversity of tetrapod limb posture and locomotor evolution, demonstrate the importance of X-ray-based techniques for revealing hidden kinematics and highlight the importance of examining locomotor function at the level of individual joint mobility.

Sagittal Profile of the Femoral Condyles and Its Application to Femorotibial Contact Analysis

2000 ◽  
Vol 123 (1) ◽  
pp. 18-26 ◽  
Author(s):  
N. Nun˜o ◽  
A. M. Ahmed
Keyword(s):  
Contact Region ◽  
Contact Analysis ◽  
Sagittal Profile ◽  
Laser Range Finder ◽  
Spring Model ◽  
Arc Model ◽  
Articular Surfaces ◽  
Simple Geometry ◽  
Nonlinear Force ◽  
Femoral Condyles

Measurements of the sagittal profiles of the articular surfaces of 24 femoral condyles were performed using a laser range finder. An algebraic algorithm was developed to reconstruct the measured sagittal profiles with simple geometry. In particular, it has been shown that a two-circular-arc model provides a very accurate reconstruction of the actual profiles in the femorotibial contact region. The average sagittal profile was used for a femorotibial contact analysis of TKA implants. The contact analysis was performed by using a rigid-body-spring model extended to the case of nonlinear force-deformation behavior of the tibial polyethylene component.

scholarly journals The effects of captive versus wild rearing environments on long bone articular surfaces in common chimpanzees (Pan troglodytes)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3668 ◽  
Author(s):  
Kristi L. Lewton
Keyword(s):  
Distal Radius ◽  
Pan Troglodytes ◽  
Articular Surface ◽  
Long Bone ◽  
Environmental Groups ◽  
Skeletal Morphology ◽  
Surface Areas ◽  
Articular Surfaces ◽  
Physical Environments ◽  
Femoral Condyles

The physical environments of captive and wild animals frequently differ in substrate types and compliance. As a result, there is an assumption that differences in rearing environments between captive and wild individuals produce differences in skeletal morphology. Here, this hypothesis is tested using a sample of 42 captive and wild common chimpanzees (Pan troglodytes). Articular surface areas of the humerus, radius, ulna, femur, and tibia were calculated from linear breadth measurements, adjusted for size differences using Mosimann shape variables, and compared across sex and environmental groups using two-way ANOVA. Results indicate that the articular surfaces of the wrist and knee differ between captive and wild chimpanzees; captive individuals have significantly larger distal ulna and tibial plateau articular surfaces. In both captive and wild chimpanzees, males have significantly larger femoral condyles and distal radius surfaces than females. Finally, there is an interaction effect between sex and rearing in the articular surfaces of the femoral condyles and distal radius in which captive males have significantly larger surface areas than all other sex-rearing groups. These data suggest that long bone articular surfaces may be sensitive to differences experienced by captive and wild individuals, such as differences in diet, body mass, positional behaviors, and presumed loading environments. Importantly, these results only find differences due to rearing environment in some long bone articular surfaces. Thus, future work on skeletal morphology could cautiously incorporate data from captive individuals, but should first investigate potential intraspecific differences between captive and wild individuals.

The Geometry of the Knee in the Sagittal Plane

1989 ◽  
Vol 203 (4) ◽  
pp. 223-233 ◽  
Author(s):  
J J O'Connor ◽  
T L Shercliff ◽  
E Biden ◽  
J W Goodfellow
Keyword(s):  
Sagittal Plane ◽  
Geometric Model ◽  
Contact Point ◽  
Contact Forces ◽  
Cruciate Ligaments ◽  
Constant Length ◽  
Articular Surfaces ◽  
Parasagittal Plane ◽  
Four Bar Linkage ◽  
The Relationship

A geometric model of the tibio-femoral joint in the sagittal plane has been developed which demonstrates the relationship between the geometry of the cruciate ligaments and the geometry of the articular surfaces. The cruciate ligaments are represented as two inextensible fibres which, with the femur and the tibia, are analysed as a crossed four-bar linkage. The directions of the ligaments at each position of flexion are calculated. The instant centre, where the flexion axis crosses the parasagittal plane through the joint, lies at the intersection of the cruciates. It moves relative to each of the bones during flexion and extension. The successive positions of the flexion axis relative to a fixed femur and to a fixed tibia are deduced. The shapes of articular surfaces which would allow the bones to flex and extend while maintaining the ligaments each at constant length are calculated and are found to agree closely with the shapes of the natural articular surfaces. The calculated movements of the contact point between the femur and the tibia during flexion also agree well with measurements made on cadaver specimens. The outcome is a geometric simulation of the tibio-femoral joint in the sagittal plane which illustrates the central role played by the cruciate ligaments in the kinematics of the knee and which can be used for the analysis of ligament and contact forces.

Transosseous Osteosynthesis with External Fixation Devices in Intraarticular Fractures of Knee Joint Area

2009 ◽  
Vol 16 (4) ◽  
pp. 29-34
Author(s):  
Igor' Olegovich Pankov ◽  
A L Emelin ◽  
I O Pankov ◽  
A L Emelin
Keyword(s):  
Knee Joint ◽  
Treatment Outcomes ◽  
External Fixation ◽  
Treatment Results ◽  
Compression Fractures ◽  
Articular Surfaces ◽  
Intraarticular Fractures ◽  
Fixation Devices ◽  
Severity Of Injury ◽  
Femoral Condyles

Peculiarities of transosseous osteosynthesis with pin-rod external fixation devices at treatment of various intraarticular fractures in the area of the knee joint are presented. Analysis of treatment outcomes for 108 patients with 110 fractures (18 fractures of femoral condyles and 92 fractures of tibial condyles) was performed. Excellent and good results were achieved in 83 (75.4%) cases. In polysegmental and impression-compression fractures of femoral and tibial condyles the treatment results were most often only satisfactory or unsatisfactory that was accounted for the severity of injury with massive destruction of the articular surfaces.

A study of the magnitude variable and running speed

1960 ◽  
Author(s):  
David Ehrenfreund ◽  
Pietro Badia
Keyword(s):  
Running Speed

Compensatory Tibial Overgrowth Following Healing of Closed Femoral Fractures in Young Dogs

1995 ◽  
Vol 08 (03) ◽  
pp. 159-162 ◽  
Author(s):  
L. Susan ◽  
R. T. O’Brien ◽  
K. A. Johnson
Keyword(s):  
Internal Fixation ◽  
Femoral Fractures ◽  
Surgical Reduction ◽  
Femoral Shortening ◽  
Hindlimb Lameness ◽  
Femoral Condyles

SummaryTwo young dogs examined for hindlimb lameness were found to have healed femoral fractures, 2-4 cm of femoral shortening, and 1 cm of compensatory ipsilateral tibial overgrowth. Neither dog had had surgery or internal fixation. Although tibial overgrowth partially corrected for limb shortening, both dogs had chronic intermittent lameness due to malformation of the femoral condyles and secondary stifle osteoarthritis.Compensatory tibial overgrowth was found in two young dogs with femoral fractures which had healed without any surgical reduction or internal fixation. Tibial overgrowth of approximately 1 cm in each case partially compensated for 2-4 cm of femoral shortening.

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