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Vertical Forces (vertical + force)
Kinds of Vertical Forces Selected AbstractsMepivacaine local anaesthetic duration in equine palmar digital nerve blocksEQUINE VETERINARY JOURNAL, Issue 8 2004L. A. BIDWELL Summary Reasons for performing study: Perineural analgesics are used for lameness diagnosis but the duration of effect, knowledge of which would provide valuable information when performing subsequent blocks, is unknown. Objective: To evaluate the duration of a palmar digital nerve block using force plate measurements. Methods: Ten horses diagnosed with unilateral navicular syndrome were trotted at range of 3 ± 0.15 m/sec over a force plate to record ground reaction forces for 5 trials of each forelimb. Data were recorded before nerve block, and then at 15 mins, 1, 2 and 24 h post nerve block. Results: Before nerve block, peak vertical force (mean ± s.e.) was significantly higher in the contralateral forelimb (CL = 5345 ± 188 N) than in the lame forelimb (L = 4256 ± 204 N; P<0.05). At 15 mins post nerve block there was no significant difference between the 2 forelimbs (CL = 5140 ± 184 N; L = 5126 ± 129 N), and this remained the case for 1 h. By 2 h, the mean score for the lame leg had decreased (L = 4642 ± 182 N) but was still greater than preblock. By 24 h, vertical forces had returned to preblock values. Conclusions: The palmar digital nerve block was fully effective between 15 mins and 1 h. The analgesic effect began to subside between 1 and 2 h but sufficient analgesia persisted to affect gait characteristics beyond 2 h. Potential relevance: When using a palmar digital nerve block, it is important to perform lameness evaluations between 15 mins and 1 h to be sure of effective nerve blockade. [source] Validation of a client-based clinical metrology instrument for the evaluation of canine elbow osteoarthritisJOURNAL OF SMALL ANIMAL PRACTICE, Issue 6 2009C. A. Hercock Objective: To validate a disease-specific client-based clinical metrology instrument (questionnaire) for dogs with chronic osteoarthritis of the elbow joint. Materialsand Methods: This was a prospective cohort study involving 26 dogs with chronic osteoarthritis of the elbow with 24 associated clients. Validity (face and criterion), reliability and responsiveness of the metrology instrument (named "Liverpool Osteoarthritis in Dogs [elbow]") were tested in a sequence of studies. Face validity involved use of international peer review. Reliability was assessed using a test-retest scenario with a two week interval; peak vertical force as measured by a force platform was used as an external standard measure. Responsiveness was tested with a two week, single-blinded placebo-controlled intervention using a licensed non-steroidal anti-inflammatory drug. Results: The reliability of Liverpool Osteoarthritis in Dogs (elbow) in the test-retest scenario was good; intraclass correlation coefficient is 0·89, 95 per cent confidence interval 0·75 to 0·95, compared with intraclass correlation coefficient 0·92, 95 per cent confidence interval 0·74 to 0·98, for peak vertical force. Responsiveness testing indicated that the "net" effect size (allowing for placebo effect) for Liverpool Osteoarthritis in Dogs (elbow) was 0·13 compared with (,)0·18 for the force platform. Criterion validity for Liverpool Osteoarthritis in Dogs (elbow) against peak vertical force was poor; Spearman's rank correlation is ,0·24 (P=0·30). Clinical Significance: Liverpool Osteoarthritis in Dogs (elbow) was considered reliable with satisfactory responsiveness. The poor criterion validity suggests a mismatch between force platform peak vertical force and client perceptions of lameness. This instrument requires further validation in larger studies with alternative client groups and alternative therapeutic interventions, but this initial validation suggests that Liverpool Osteoarthritis in Dogs (elbow) is worthy of continued investigation. [source] Double-Blind Placebo-Controlled Trial of Adjuvant Pamidronate with Palliative Radiotherapy and Intravenous Doxorubicin for Canine Appendicular Osteosarcoma Bone PainJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2009T.M. Fan Background: Canine osteosarcoma (OSA) causes focal malignant osteolysis leading to severe pain. Despite the documented efficacy of radiotherapy or IV aminobisphosphonates for managing cancer bone pain, their potential combined therapeutic value has not been reported in OSA-bearing dogs. Hypothesis: Pamidronate combined with standardized palliative therapy will improve pain control and bone biologic effects in OSA-bearing dogs. Animals: Fifty dogs with appendicular OSA treated with standardized palliative therapy and either pamidronate or sterile saline. Methods: Randomized, prospective, double-blinded, placebo-controlled study. Treatment responses for dogs receiving standardized palliative therapy with (n = 26) or without (n = 24) adjuvant pamidronate were serially evaluated for changes in subjective pain scores, urine N-telopeptide (NTx) excretion, primary tumor relative bone mineral density (rBMD), and computerized pressure platform gait analysis. Results: Median duration of subjective pain relief for dogs treated with adjuvant pamidronate or placebo was 76 and 75 days, respectively (P= .39). Forty percent (20/50; pamidronate [11/26] and placebo [9/24]) of dogs experienced durable analgesia, defined by pain alleviation ,112 days. For patients achieving durable pain control, dogs treated with pamidronate achieved greater reductions in NTx excretion and larger increases in rBMD compared with placebo controls. Changes in peak vertical force assessed by computerized pressure platform gait analysis correlated with pain alleviation in OSA-bearing dogs. Conclusions and Clinical Importance: Combining pamidronate with standardized palliative therapy is safe, but does not clearly improve pain alleviation. However, in dogs achieving durable pain control, adjuvant pamidronate appears to decrease focal bone resorption in the local tumor microenvironment. [source] Cyclic tests on steel and concrete-filled tube frames with Slit WallsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2007Toko Hitaka Abstract Cyclic loading tests were performed on three one-storey steel frames and four three-storey concrete-filled tube (CFT) moment frames reinforced with a new type of earthquake-resisting element consisting of a steel plate shear wall with vertical slits. In this shear wall system, the steel plate segments between the slits behave as a series of flexural links, which provide fairly ductile response without the need for heavy stiffening of the wall. The steel shear walls and the moment frames behaved in a ductile manner up to more than 4% drift without abrupt strength degradation or loss of axial resistance. Results of these tests and complementary analysis provide a basis for an equivalent brace model to be employed in commercially available frame analysis programs. Test and analytical results suggest that the horizontal force is carried by the bolts in the middle portion of the wall,frame connection, while the vertical forces coupled with the moment in the connection are resisted by the bolts in the edge portion of the connection, for which the friction bolts in the connection should be designed. When sufficient transverse stiffening is provided, full plastic strength and non-degrading hysteretic behaviour can be achieved for this new type of shear wall. Copyright © 2006 John Wiley & Sons, Ltd. [source] Mepivacaine local anaesthetic duration in equine palmar digital nerve blocksEQUINE VETERINARY JOURNAL, Issue 8 2004L. A. BIDWELL Summary Reasons for performing study: Perineural analgesics are used for lameness diagnosis but the duration of effect, knowledge of which would provide valuable information when performing subsequent blocks, is unknown. Objective: To evaluate the duration of a palmar digital nerve block using force plate measurements. Methods: Ten horses diagnosed with unilateral navicular syndrome were trotted at range of 3 ± 0.15 m/sec over a force plate to record ground reaction forces for 5 trials of each forelimb. Data were recorded before nerve block, and then at 15 mins, 1, 2 and 24 h post nerve block. Results: Before nerve block, peak vertical force (mean ± s.e.) was significantly higher in the contralateral forelimb (CL = 5345 ± 188 N) than in the lame forelimb (L = 4256 ± 204 N; P<0.05). At 15 mins post nerve block there was no significant difference between the 2 forelimbs (CL = 5140 ± 184 N; L = 5126 ± 129 N), and this remained the case for 1 h. By 2 h, the mean score for the lame leg had decreased (L = 4642 ± 182 N) but was still greater than preblock. By 24 h, vertical forces had returned to preblock values. Conclusions: The palmar digital nerve block was fully effective between 15 mins and 1 h. The analgesic effect began to subside between 1 and 2 h but sufficient analgesia persisted to affect gait characteristics beyond 2 h. Potential relevance: When using a palmar digital nerve block, it is important to perform lameness evaluations between 15 mins and 1 h to be sure of effective nerve blockade. [source] In vivo horizontal forces on implants depending on the type of occlusionJOURNAL OF ORAL REHABILITATION, Issue 9 2002T. MORNEBURG Minimizing horizontal forces on implants is one of the important aims of an occlusal design. Therefore, several proposals have been made in literature, e.g. flat cuspal slopes or narrow occlusal surfaces. Our aim was to test how these occlusal designs would influence horizontal forces. Ten healthy subjects with unilateral partially edentulous arches were provided with fixed partial dentures (FPD) on two ITI-implants. The opposing jaw was fully dentate. After an adaptation of 6 month measurement setups with a measuring FPD were put into the mouth. The sensoring device, which consisted of two abutments equipped with strain gauges, evaluated the forces in three dimensions. For each person three FPDs were made with a different design of the occlusal surface. The first FPD exhibited cusps with steep slopes (S), the second showed flat cusps (F) and the third had a narrow occlusal surface (N). The peak forces of the chewing cycles of each patient were evaluated. While chewing wine gum the average values of the vertical forces of the three different FPDs showed no significant differences and amounted to between 253·8 N (s.d. 85·7 N) and 273·9 N (s.d. 63·7 N). With the first FPD (S) mean horizontal forces of 47·9 N (s.d. 34·8 N) were found whereas with the flat surface an average force of 47·4 N (s.d. 37·1 N) was measured. The narrow occlusal surface was associated with an average reduction of the horizontal forces of about 50·9% to a mean value of 24·4 N (s.d. 10·6 N) (P < 0·005). The inclination of occlusal slopes did neither affect vertical nor horizontal forces significantly. However, narrowing of the occlusal surface in the oro-vestibular direction by 30% showed a significant reduction of the lateral forces exerted on the implants by more than 50%. A reduced oro-vestibular width of the occlusal surface is recommended especially for diameter-reduced implants, in case of an unfavourable relationship between implant and crown length or for implants that are strongly inclined to the occlusal plane. [source] Biomechanical effects of double or wide implants for single molar replacement in the posterior mandibular regionJOURNAL OF ORAL REHABILITATION, Issue 10 2000Y. Sato Double implants have been thought to have biomechanical advantages for single molar replacement. To evaluate the effectiveness of double implants versus a wide implant, the vertical forces and torque on each implant were calculated by three-dimensional geometric analysis. Buccal load (100 N) perpendicular to cuspal inclination (20°) was applied at the occlusal surface of the superstructure. The three kinds of load points (A, B, C) were 1·5, 3·5, and 5·5 mm from the mesial contact point, respectively. Three implants were compared: mesial and distal double implants (, 3·3 mm), and a wide implant (, 5 mm). The wide implant showed torque around the long axis (1·8,15·0 N · cm) whereas double implants had no torque. On the other hand, the vertical forces on the mesial double implant were both smaller (60%: loaded at point C) and larger (140%: loaded at point A) than the wide implant. Given the smaller surface area of the mesial double implant, this large force may generate much higher stress in the peri-implant bone. These results suggest that the biomechanical advantage of double implants for single molar replacement is questionable when the occlusal force is loaded at the occlusal surface near the contact point. [source] Stress distribution associated with loaded ceramic onlay restorations with different designs of marginal preparation.JOURNAL OF ORAL REHABILITATION, Issue 4 2000An FEA study The design of marginal finish of an inlay or onlay could influence the prognosis of the restoration since this area is subjected to various mechanical or chemical actions during function. This study was carried out to determine the tensile stresses which develop at the marginal area when subjected to vertical and horizontal loads. Onlay restorations with three different types of marginal finish, i.e. shoulder, chamfer and bevel, were modelled in three dimensions using the finite element method, and were then subjected to vertical and horizontal load at three different sites. The results show that horizontal forces acting on the restoration generate the highest tensile stresses whilst the vertical forces generate high tensile stresses at the margins of the chamfer and bevel designs. [source] Effect of elbow flexion contractures on the ability of people with C5 and C6 tetraplegia to liftPHYSIOTHERAPY RESEARCH INTERNATIONAL, Issue 2 2001Lisa Harvey Abstract Background and Purpose It is commonly assumed that minor elbow flexion contractures prevent people with C5,C6 tetraplegia and paralysis of the triceps brachii muscles from bearing full body weight through their upper limbs. The aim of the present study was to determine the effect of simulated bilateral elbow flexion contractures on the ability of these individuals to bear weight through their upper limbs and to determine whether full passive elbow extension is truly critical for lifting body weight. Method A biomechanical study was performed. Body weight lifted was measured under conditions that simulated bilateral elbow flexion contractures. Five people with motor complete C6 tetraplegia and one person with motor complete C5 tetraplegia, all with bilateral paralysis of the triceps brachii muscles, were recruited to the study. Subjects were fitted with bilateral elbow splints that restricted elbow extension but did not restrain elbow flexion nor prevent the elbow from collapsing, and were seated on an instrumented platform that measured vertical forces under the buttocks. Subjects pushed down through their hands and lifted under five different conditions, namely: with no elbow splints; with bilateral elbow splints adjusted to restrict elbow extension by 5,10°; by 15,20°; by 25,30° and with bilateral elbow splints adjusted to allow unrestricted movement of the elbow joint. Maximal weight lifted from under the buttocks, for each condition, was expressed in relation to weight under the buttocks during unsupported sitting (that is, ,seated body weight'). Results Subjects lifted progessively less weight from under their buttocks as passive elbow restriction was progressively restricted. However, one subject lifted all his seated body weight when elbow extension was restricted by 5,10° and another lifted all his seated body weight when elbow extension was restricted by 5,10° and 15,20°. Conclusions Minor elbow flexion contractures will not alone prevent people with tetraplegia and paralysis of the triceps brachii muscles from lifting. Full passive elbow extension is not critical for the performance of this task. Copyright © 2001 Whurr Publishers Ltd. [source] Brief communication: Forelimb compliance in arboreal and terrestrial opossumsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Daniel Schmitt Abstract Primates display high forelimb compliance (increased elbow joint yield) compared to most other mammals. Forelimb compliance, which is especially marked among arboreal primates, moderates vertical oscillations of the body and peak vertical forces and may represent a basal adaptation of primates for locomotion on thin, flexible branches. However, Larney and Larson (Am J Phys Anthropol 125 [2004] 42,50) reported that marsupials have forelimb compliance comparable to or greater than that of most primates, but did not distinguish between arboreal and terrestrial marsupials. If forelimb compliance is functionally linked to locomotion on thin branches, then elbow yield should be highest in marsupials relying on arboreal substrates more often. To test this hypothesis, we compared forelimb compliance between two didelphid marsupials, Caluromys philander (an arboreal opossum relying heavily on thin branches) and Monodelphis domestica (an opossum that spends most of its time on the ground). Animals were videorecorded while walking on a runway or a horizontal 7-mm pole. Caluromys showed higher elbow yield (greater changes in degrees of elbow flexion) on both substrates, similar to that reported for arboreal primates. Monodelphis was characterized by lower elbow yield that was intermediate between the values reported by Larney and Larson (Am J Phys Anthropol 125 [2004] 42,50) for more terrestrial primates and rodents. This finding adds evidence to a model suggesting a functional link between arboreality,particularly locomotion on thin, flexible branches,and forelimb compliance. These data add another convergent trait between arboreal primates, Caluromys, and other arboreal marsupials and support the argument that all primates evolved from a common ancestor that was a fine-branch arborealist. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Substrate determines asymmetrical gait dynamics in marmosets (Callithrix jacchus) and squirrel monkeys (Saimiri boliviensis)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Jesse W. Young Abstract Studies of skeletal pathology indicate that injury from falling accounts for most long bone trauma in free-ranging primates, suggesting that primates should be under strong selection to manifest morphological and behavioral mechanisms that increase stability on arboreal substrates. Although previous studies have identified several kinematic and kinetic features of primate symmetrical gaits that serve to increase arboreal stability, very little work has focused on the dynamics of primate asymmetrical gaits. Nevertheless, asymmetrical gaits typify the rapid locomotion of most primates, particularly in smaller bodied taxa. This study investigated asymmetrical gait dynamics in growing marmosets and squirrel monkeys moving on terrestrial and simulated arboreal supports (i.e., an elevated pole). Results showed that monkeys used several kinematic and kinetic adjustments to increase stability on the pole, including reducing peak vertical forces, limiting center of mass movements, increasing substrate contact durations, and using shorter and more frequent strides (thus limiting disruptive whole-body aerial phases). Marmosets generally showed greater adjustment to pole locomotion than did squirrel monkeys, perhaps as a result of their reduced grasping abilities and retreat from the fine-branch niche. Ontogenetic increases in body size had relatively little independent influence on asymmetrical gait dynamics during pole locomotion, despite biomechanical theory suggesting that arboreal instability is exacerbated as body size increases relative to substrate diameter. Overall, this study shows that 1) symmetrical gaits are not the only stable way to travel arboreally and 2) small-bodied primates utilize specific kinematic and kinetic adjustments to increase stability when using asymmetrical gaits on arboreal substrates. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] The relationship between limb morphology, kinematics, and force during running: the evolution of locomotor dynamics in lizardsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009ERIC J. MCELROY Terrestrial locomotion occurs via the hierarchical links between morphology, kinematics, force, and center-of-mass mechanics. In a phylogenetically broad sample of seven lizard species, we show that morphological variation drives kinematic variation, which, in turn, drives force variation. Species with short limbs use a short stride,high frequency strategy when running at steady-speed and to change speeds. This link between morphology and kinematics results in relatively small vertical forces during the support phase of the stride cycle. Conversely, species with long limbs use a long stride,low frequency strategy, resulting in large vertical forces during the support phase. In view of these findings, we suggest that limb length may predict locomotor energetics in lizards because energetics are largely determined by vertical forces and stride frequency. Additionally, we propose an energetic trade-off with both long- and short-limbed species paying the most energy to move, whereas intermediate-limbed species move using less energy. Finally, when these traits are mapped onto a lizard phylogeny, we show that locomotor functional morphology exhibits both deep phylogenetic effects and contemporary patterns of evolutionary convergence. Overall, the present study provides a foundation for testing hypotheses regarding the integration and evolution of functional traits in lizards and animals in general. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 634,651. [source] | |||||||||||||