scholarly journals The Relationship Between Knee Motion and Articular Surface Geometry

1990 ◽  
pp. 269-286 ◽  
Author(s):  
R. Huiskes ◽  
L. Blankevoort
Keyword(s):  
Articular Surface ◽  
Surface Geometry ◽  
Knee Motion ◽  
The Relationship

Effect of Calcaneal Lengthening on Relationships among the Hindfoot, Midfoot, and Forefoot

Foot & Ankle ◽  
1993 ◽  
Vol 14 (3) ◽  
pp. 136-141 ◽  
Author(s):  
Bruce J. Sangeorzan ◽  
Vincent Mosca ◽  
Sigvard T. Hansen
Keyword(s):  
Pitch Angle ◽  
Articular Surface ◽  
Angular Measurement ◽  
Pes Planus ◽  
Lateral Column ◽  
Medial Side ◽  
Significant Correction ◽  
Before And After ◽  
Calcaneal Lengthening ◽  
The Relationship

To better understand the bony component of pes planus and the means by which the Evans calcaneal lengthening corrects them, we studied the standing radiographs of seven adult patients who had undergone calcaneal lengthening to treat symptomatic pes planus. Weightbearing AP and lateral views done preoperatively and postoperatively were used for the study. For each set of films, the following parameters were measured: on the lateral view; overall length of the calcaneus, lateral talometatarsal angle, lateral talocalcaneal angle, and the calcaneal pitch angle; and on the dorsoplanar view, the talometatarsal and talocalcaneal angle. In addition, the relative coverage of the talus by the navicular was described by an angular measurement based on the relationship of the center of the talus to the center of the navicular. The average improvements in lateral talocalcaneal angle (a reflection of hind-foot valgus) was 6.4° when the long axis of the calcaneus was used and 6.8° when the inferior surface of the calcaneus was used for the measurement. The lateral talometatarsal angle improved an average 11.3° (from an average of 19.7° to 8.4°). The dorsoplantar talometatarsal angle (a measure of forefoot adduction/abduction) improved 15.8° (preoperative average 26.8°, postoperative average 11°). The calcaneal pitch angle improved an average 10.8° (preoperative average 3.2°, postoperative average 14°). The relationship between the talus and navicular was defined by an angular measurement based on the center of each articular surface before and after correction using this measurement. An average improvement of 26° occurred in the alignment of these two articular surfaces. This study confirms Evans' belief that significant correction can be obtained by lateral column lengthening, that the relationship between navicular and talus can be restored without fusion, and that the forefoot position corrects without operative intervention to the medial side of the foot. This study also provides numerical guidelines for the surgeon planning surgical correction of symptomatic pes planus, and since bony relationships can be observed before and after correction, some insight may be gained into tarsal morphology of pes planus.

Contribution of Articular Surface Geometry to Ankle Stabilization

2006 ◽  
Vol 88 (12) ◽  
pp. 2704-2713 ◽  
Author(s):  
Yuki Tochigi ◽  
M. James Rudert ◽  
Charles L. Saltzman ◽  
Annunziato Amendola ◽  
Thomas D. Brown
Keyword(s):  
Articular Surface ◽  
Surface Geometry

scholarly journals Assessing the accumulated stickiness magnitude from fabric–skin friction: effect of wetness level of various fabrics

2018 ◽  
Vol 5 (8) ◽  
pp. 180860 ◽  
Author(s):  
Ka-Po Maggie Tang ◽  
Kam-Hong Chau ◽  
Chi-Wai Kan ◽  
Jin-tu Fan
Keyword(s):  
Growth Rate ◽  
Recovery Period ◽  
Skin Surface ◽  
Cotton Fabrics ◽  
Surface Geometry ◽  
Intimate Apparel ◽  
Fixed Stimulus ◽  
Skin Wetness ◽  
The Difference ◽  
The Relationship

Increasing skin wetness tends to increase fabric–skin adhesion and friction, resulting in wear discomfort or skin injuries. Here, the magnitude estimation approach was used to assess the stickiness sensation perceived in fabrics. Seven fabric types were wetted by putting onto wet ‘skin’ surface and dried for different durations to achieve different wetness levels, simulating wearing conditions during the recovery period after sweating. Results showed that the relationship between magnitude estimates of stickiness and amount of water present in fabric demonstrated a power function. The exponents and constant from power regression show the growth rate of stickiness sensation with moisture intensity and the perceived stickiness under fixed stimulus intensity, respectively. A novel parameter, accumulated stickiness magnitude (ASM), describing how much discomfort a wetted fabric offered throughout the drying period, was developed. Thin cotton fabrics (fabric W01 and W03), having higher saturation level after contacting with wetted skin surface, arouse stronger stickiness feeling and their ASM is remarkably higher. The difference in stickiness estimates is due to the difference in chemical composition and surface geometry. This study suggests us the way to predict perceived stickiness in fabrics with different wetness levels which is useful for applications like sportswear, intimate apparel or healthcare products.

scholarly journals Surface geometry, miniaturization and metrology

2012 ◽  
Vol 370 (1973) ◽  
pp. 4042-4065 ◽  
Author(s):  
David J. Whitehouse
Keyword(s):  
Surface Geometry ◽  
Precision Engineering ◽  
Performance Change ◽  
Surface System ◽  
Ultra Precision ◽  
The Relationship

Ultra-precision engineering has at its core the size, shape and texture of the components used. This study examines how the relationship between them and their role is changing with respect to manufacture, function and characterization, with particular emphasis on aspects of miniaturization and ultra-precision engineering. Surface geometry has traditionally been linked to the generation of part size. This is changing: the study shows that it is now possible to separate shape and texture from the size generation and to design them independently for function. In addition, with miniaturization, the roles and properties of shape and texture that affect performance change considerably, especially those tribological functions involving contact and flow. This study reveals these changes and shows how the characterization of the surfaces making up a surface system can take these into account.

Osteochondral Allograft Donor-Host Matching by the Femoral Condyle Radius of Curvature

2016 ◽  
Vol 45 (2) ◽  
pp. 403-409 ◽  
Author(s):  
Derek T. Bernstein ◽  
Craig A. O’Neill ◽  
Ryan S. Kim ◽  
Hugh L. Jones ◽  
Philip C. Noble ◽  
...  
Keyword(s):  
Conventional Method ◽  
Articular Surface ◽  
Femoral Condyle ◽  
Osteochondral Allograft ◽  
Radius Of Curvature ◽  
Surface Geometry ◽  
Match Rate ◽  
Matching Criteria ◽  
Matching Techniques ◽  
Femoral Condyles

Background: Conventional osteochondral allograft (OCA) matching, requiring orthotopic, size-matched condyles, and narrow surgical time windows often prohibit timely transplantation. Hypothesis: The femoral condyle radius of curvature (RoC) is an appropriate, isolated criterion for donor-host matching in fresh OCAs, potentially enhancing matching efficiency when compared with conventional matching techniques. Study Design: Descriptive laboratory study. Methods: In part 1 of this study, 3-dimensional digital reconstructions of 14 randomly selected, cadaveric distal femoral hemicondyles were performed. Each condyle was divided into anterior, middle, and posterior zones. A virtual best-fit grid was applied to each, and each zone’s sagittal- and coronal-plane RoCs were determined. Seven nonorthotopic OCA transplantations were performed based on RoC matching with 1-mm tolerance, and the preoperative and postoperative surface geometry were quantified to assess the accuracy of articular surface restoration. Of note, each donor-host pair did not match by the conventional method. In part 2 of this study, 12 cadaveric distal femora were categorized by size and digitized in the aforementioned manner. Simulated circular defects measuring 20, 25, and 30 mm in diameter were introduced into each zone. OCA matches were determined based on donor and host RoCs, and the total number of potential matches (of 71 total comparisons) was recorded as a percentage for each simulated defect. Finally, the results of RoC matching were compared with the conventional method for simulated defects in all zones of both the medial and lateral femoral condyles. Results: Part 1: The mean surface deviation after OCA transplantation was −0.09 mm, with a mean maximum protrusion at any point of 0.59 mm. Part 2: Using the RoC, 20-mm defects had a 100% chance of being matched. Defects of 25 and 30 mm had a 91% and 64% chance of being matched, respectively. Compared with the conventional method, the RoC method yielded a 3.2-fold greater match rate for lesions of the medial and lateral femoral condyles ( P = .02). Conclusion: This investigation shows that femoral condyle RoCs in the sagittal and coronal planes may be useful, alternative matching criteria, expanding on current standards. Clinical Relevance: These matching criteria may increase the number of available matches, reduce wait times for patients, and reduce the number of wasted grafts.

scholarly journals The relationship between subglacial water pressure and velocity of Findelengletscher, Switzerland, during its advance and retreat

1997 ◽  
Vol 43 (144) ◽  
pp. 328-338 ◽  
Author(s):  
Almut Iken ◽  
Martin Truffe
Keyword(s):  
Water Pressure ◽  
Pressure Fluctuations ◽  
Drainage System ◽  
Surface Strain ◽  
Aerial Photographs ◽  
Surface Velocity ◽  
Surface Geometry ◽  
Sliding Speed ◽  
Pressure Surface ◽  
The Relationship

AbstractFindelengletscher, Switzerland, advanced about 250 m between 1979 and 1985, and retreated thereafter. Subglacial water pressure, surface velocity and surface strain rate were determined at several sites. The measurements were made early in the melt seasons of 1980, 1982, 1985 and 1994 and in the autumn of 1983 and the winter of 1984. Changes of surface geometry were assessed from aerial photographs.The estimated basal shear stress changed little between 1982 and 1994. Nevertheless, large changes in the relationship of subglacial water pressure and surface velocity were observed, which cannot be reconciled with the most commonly used sliding law unless it is modified substantially. Consideration of possible reasons indícales that a change in the subglacial drainage system occurred, probably involving a change in the degree of cavity interconnection. Isolated cavities damp the variations in sliding velocity that normally result from changes in water pressure, because the pressure in isolated cavities decreases as the sliding speed increases. In contrast, by transmitting water-pressure fluctuations to a larger area of the bed, interconnected cavities amplify the effect of water-pressure fluctuations on sliding speed. Thus, we suggest that an observed decrease in velocity (for a given water pressure) between 1982 and 1994 was a consequence of a decrease in the interconnectedness of the subglacial cavity system.

scholarly journals Comparison of Computed Tomography Articular Surface Geometry of Male Versus Female Thumb Carpometacarpal Joints

Hand ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 33-39
Author(s):  
Jessica G. Shih ◽  
James G. Mainprize ◽  
Paul A. Binhammer
Keyword(s):  
Sex Differences ◽  
Articular Surface ◽  
Joint Space ◽  
Joint Surface ◽  
Surface Geometry ◽  
Significant Difference ◽  
The Mean ◽  
Joint Congruence ◽  
Cmc Joint ◽  
Space Volume

Background: Given the predilection of first carpometacarpal (CMC) joint osteoarthritis in women compared with men, we aim to determine the differences in first CMC joint surface geometry and congruence between young healthy males and females. Methods: Wrist computed tomographic scan data of 11 men and 11 women aged 20 to 35 years were imported into 3-dimensional software programs. The first metacarpal and the trapezium were aligned in a standardized position according to landmarks at key points on Gaussian and maximum curvature maps. Measurements of joint congruence and surface geometry were analyzed, including joint space volume, distance between the bones at the articular surface edges, area of the joint space, and radii of curvature in the radial-ulnar and volar-dorsal planes. Results: The mean thumb CMC articular space volume was 104.02 ± 30.96 mm3 for females and 138.63 ± 50.36 mm3 for males. The mean first metacarpal articular surface area was 144.9 ± 10.9 mm2 for females and 175.4 ± 25.3 mm2 for males. After normalizing for size, the mean thumb CMC articular space volume was 119.4 ± 24.6 mm3 for females and 117.86 ± 28.5 mm3 for males. There was also no significant difference for the articular space volume, articular surface distances, articular space, and mean radii of curvatures. Conclusions: This study found that there are sex differences in the first CMC joint articular volume without normalizing for size; however, there are no sex differences in first CMC joint articular volume, curvature characteristics, or joint congruence of young, healthy patients after normalizing for joint size.

scholarly journals Basal traction mainly dictated by hard-bed physics over grounded regions of Greenland

2020 ◽  
Author(s):  
Nathan Maier ◽  
Florent Gimbert ◽  
Fabien Gillet-Chaulet ◽  
Adrien Gilbert
Keyword(s):  
Spatial Relationship ◽  
Greenland Ice Sheet ◽  
Surface Geometry ◽  
Ice Dynamics ◽  
Ice Flow ◽  
Warming Climate ◽  
Interpretation Biases ◽  
The Relationship ◽  
Insight Into ◽  
Large Grid

Abstract. On glaciers and ice sheets, identifying the relationship between velocity and traction is critical to constrain the bed physics that control ice flow. Yet in Greenland, these relationships remain unquantified. We determine the spatial relationship between velocity and traction in all eight drainage catchments of Greenland. The basal traction is estimated using three different methods over large grid cells to minimize interpretation biases associated with unconstrained rheologic parameters used in numerical inversions. We find the relationships are consistent with our current understanding of basal physics in each catchment. We identify catchments that predominantly show Mohr-Coulomb-like behavior typical of deforming beds or significant cavitation, as well as catchments that predominantly show rate-strengthening behavior typical of Weertman-type hard-bed physics. Overall, the traction relationships suggest that the flow field and surface geometry over the grounded regions of the Greenland ice sheet is mainly dictated by Weertman-type hard-bed physics. Given the complex basal boundary across Greenland, the relationships are captured surprisingly well by simple traction laws over the entire velocity range, including regions with velocities over 1000 m/yr, which provide a parameterization that can be used to model ice dynamics at large scales. The results and analysis serve as a fundamental constraint on the physics of basal motion in Greenland and provide unique insight into future dynamics and vulnerabilities in a warming climate.

Depth dependent osmotic and swelling properties of cartilage

2012 ◽  
Vol 1418 ◽  
Author(s):  
Candida Silva ◽  
Iren Horkayne-Szakaly ◽  
Preethi Chandran ◽  
Emilios K. Dimitriadis ◽  
David Lin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Articular Surface ◽  
Swelling Pressure ◽  
Osmotic Swelling ◽  
Swelling Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Joint Surfaces ◽  
And Function ◽  
The Relationship

ABSTRACTArticular cartilage is a low-friction, load-bearing tissue located at joint surfaces. It experiences static and dynamic forces including shear, compression and tension. We investigate the relationship between structure and function by measuring the osmotic and mechanical properties in cartilage layers as a function of the distance from the articular surface. Atomic force microscopy is used to probe the mechanical properties at high spatial resolution. The mechanical measurements are complemented by osmotic swelling pressure observations made on the same samples using a novel tissue osmometer. The results show that the osmotic modulus significantly depends on the distance from the articular surface. Its value is highest in the deep zone and lowest in the middle zone.

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