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Limb Position (limb + position)
Selected AbstractsRadiological interpretation of the navicular boneEQUINE VETERINARY EDUCATION, Issue 5 2008S. Dyson Summary Acquisition of a sufficient number of high quality radiographic views is an essential prerequisite to accurate radiological interpretation of the navicular bone. This requires appropriate preparation of the foot, careful attention to limb position and to both centring and direction of the x-ray beam, according to hoof capsule conformation. Artefacts are easily created. Potentially significant radiological abnormalities include: entheseiophytes at the proximomedial and proximolateral aspect of the bone; proximal or distal extension of the flexor border of the bone, distal border fragments, 8 or more large and variably shaped distal border radiolucent zones; discrete radiolucent areas in the spongiosa with or without detectable communication with the flexor cortex; new bone at the sagittal ridge; increased thickness of the flexor cortex; sclerosis of the spongiosa; and a bipartite bone. [source] Effects of rotation on measurement of lower limb alignment for knee osteotomyJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2004Hideo Kawakami Abstract The purposes of this study were to clarify the effects of rotation on two-dimensional measurement of lower limb alignment for knee osteotomy using a three-dimensional method and to determine whether this 3-D simulation method could help with planning of knee osteotomy. We developed computer software to calculate femorotibial angle (FTA) and hip,knee,ankle angle (HKA) and simulate knee osteotomy from a CT-based 3-D bone model of the lower limb. Lower limb rotation on anteroposterior long-standing radiographs was measured by superimposing the 3-D bone models. Changes in alignment with limb rotation were calculated using the software. FTA after virtual closed-wedged osteotomy was measured for a hypothetical case of a rotation error of the osteotomy plane in reattaching the proximal cutting surface to the distal cutting surface. For 31 varus knees in 20 patients with medial compartment arthritis, the mean rotation angle, relative to the epicondylar axis, with variable limb position was 7.4 ± 3.9° of internal rotation (mean ± SD), ranging from 8° of external rotation to 14° of internal rotation; the mean changes in FTA and HKA were 3.5 ± 2.2° (range, 0.4,8.6) and 1.6 ± 1.3° (range, 0.2,4.9), respectively. The FTA "flexion angle" (lateral view alignment from neutral AP) and the absolute HKA "flexion angle" correlated with the change in FTA and HKA with limb rotation, respectively (FTA, R = 0.999; HKA, R = 0.993). The mean change in FTA after virtual closed-wedged osteotomy was 3.2° for internal and external 10° rotation errors in reattaching the osteotomy plane. Rotation may affect measurement of lower limb alignment for knee osteotomy, and 3-D methods are preferable for surgical planning. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Understanding hind limb weight support in chimpanzees with implications for the evolution of primate locomotionAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009David A. Raichlen Abstract Most quadrupedal mammals support a larger amount of body weight on their forelimbs compared with their hind limbs during locomotion, whereas most primates support more of their body weight on their hind limbs. Increased hind limb weight support is generally interpreted as an adaptation that reduces stress on primates' highly mobile forelimb joints. Thus, increased hind limb weight support was likely vital for the evolution of primate arboreality. Despite its evolutionary importance, the mechanism used by primates to achieve this important kinetic pattern remains unclear. Here, we examine weight support patterns in a sample of chimpanzees (Pan troglodytes) to test the hypothesis that limb position, combined with whole body center of mass position (COM), explains increased hind limb weight support in this taxon. Chimpanzees have a COM midway between their shoulders and hips and walk with a relatively protracted hind limb and a relatively vertical forelimb, averaged over a step. Thus, the limb kinematics of chimpanzees brings their feet closer to the COM than their hands, generating greater hind limb weight support. Comparative data suggest that these same factors likely explain weight support patterns for a broader sample of primates. It remains unclear whether primates use these limb kinematics to increase hind limb weight support, or whether they are byproducts of other gait characteristics. The latter hypothesis raises the intriguing possibility that primate weight support patterns actually evolved as byproducts of other traits, or spandrels, rather than as adaptations to increase forelimb mobility. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Muscle spindle signals combine with the sense of effort to indicate limb positionTHE JOURNAL OF PHYSIOLOGY, Issue 3 2005J. A. Winter Experiments were carried out to test the hypothesis that, in the absence of vision, position sense at the human forearm is generated by the combined input from muscle spindles in elbow flexor muscles and signals of central origin giving rise to a sense of effort. In a forearm position-matching task, to remove a possible contribution from the sense of effort, the reference arm was held supported at the test angle. Subjects were less accurate in matching elbow position of the supported forearm than when it was unsupported. Adding a 2 kg weight to the unsupported reference arm led subjects to make matching errors consistent with an increase in the effort signal. Evidence of a contribution from muscle spindles was provided by showing that the direction of position matching errors could be systematically altered by flexion or extension conditioning of the reference arm before its placement at the test angle. Such changes in errors with conditioning could be shown to be present when the reference arm was supported, unsupported, or unsupported and weighted. It is concluded that both peripheral signals from muscle spindles and signals of central origin, associated with the motor command required to maintain arm position against the force of gravity, can provide information about forearm position. [source] Manual digital pressures during knuckle-walking in chimpanzees (Pan troglodytes)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009R.E. Wunderlich Abstract Considerable attention has been given to hand morphology and function associated with knuckle-walking in the African apes because of the implications they have for the evolution of bipedalism in early hominins. Knuckle-walking is associated with a unique suite of musculoskeletal features of the wrist and hand, and numerous studies have hypothesized that these anatomical features are associated with the dynamics of load distribution across the digits during knuckle-walking. We collected dynamic digital pressures on two chimpanzees during terrestrial and simulated arboreal locomotion. Comparisons were made across substrates, limb positions, hand positions, and age categories. Peak digital pressures were similar on the pole and on the ground but were distributed differently across the digits on each substrate. In young animals, pressure was equally high on digits 2,4 on the ground but higher on digits 3 and 4 on the pole. Older animals experience higher pressures on digits 2 and 3 on the ground. Hand posture (palm-in vs. palm-back) influenced the distribution and timing of peak pressures. Age-related increases in body mass also result in higher overall pressures and increased variation across the digital row. In chimpanzees, digit 5 typically bears relatively little load regardless of hand position or substrate. These are the first quantitative data on digital pressures during knuckle-walking in hominoids, and they afford the opportunity to develop hypotheses about variation among hominoids and biomechanical models of wrist and forearm loading. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] 3D Computerized Model for Measuring Strain and Displacement of the Brachial Plexus Following Placement of Reverse Shoulder ProsthesisTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 9 2008Tom Van Hoof Abstract The aim of the present study was to develop a method for three-dimensional (3D) reconstruction of the brachial plexus to study its morphology and to calculate strain and displacement in relation to changed nerve position. The brachial plexus was finely dissected and injected with contrast medium and leaden markers were implanted into the nerves at predefined places. A reverse shoulder prosthesis was inserted in a cadaveric specimen what induced positional change in the upper limb nerves. Computed tomography (CT) was performed before and after this surgical intervention. The computer assisted image processing package Mimics® was used to reconstruct the pre- and postoperative brachial plexus in 3D. The results show that the current interactive model is a realistic and detailed representation of the specimen used, which allows 3D study of the brachial plexus in different configurations. The model estimated strains up to 15.3% and 19.3% for the lateral and the medial root of the median nerve as a consequence of placing a reverse shoulder prosthesis. Furthermore, the model succeeded in calculating the displacement of the brachial plexus by tracking each implanted lead marker. The presented brachial plexus 3D model currently can be used in vitro for cadaver biomechanical analyses of nerve movement to improve diagnosis and treatment of peripheral neuropathies. The model can also be applied to study the exact location of the plexus in unusual upper limb positions like during axillary radiation therapy and it is a potential tool to optimize the approaches of brachial plexus anesthetic blocks. Anat Rec, 291:1173-1185, 2008. © 2008 Wiley-Liss, Inc. [source] | ||||||||||