Search Results

You are looking at 1 - 10 of 690 items for :

  • Refine by Access: All Content x
Clear All
Restricted access

Sheena S. Philip, Joy C. Macdermid, Saranya Nair, Dave Walton, and Ruby Grewal

Distal radius fracture (DRF) is a common, debilitating injury of the upper extremity with a crude incidence of 175.5/100,000 persons in the United States ( Orces & Martinez, 2010 ). The number of older adults (>50 years) who received treatment for forearm and hand fractures increased by 15.2% in U

Restricted access

Karl M. Newell and Gareth Irwin

A long-held viewpoint in the coordination and control of human movement is that the emerging kinetic/kinematic output within both the upper (i.e., shoulder, elbow, wrist) and lower (i.e., hip, knee, ankle) limb patterns of joint motion follows a proximal–distal sequential order. The proximal–distal

Restricted access

Ben Serrien, Maggy Goossens, and Jean-Pierre Baeyens

, Della-Grasta, Farrell, & Laurent, 1997 ). Despite this great complexity and variations between different sport motions, typical overhand throwing and striking actions show similar topological proximal-to-distal (P-D) sequencing patterns in muscle activity and kinematics ( Hirashima, Kadota, Sakurai

Restricted access

Katie Crockett, Saija A. Kontulainen, Jonathan P. Farthing, Philip D. Chilibeck, Brenna Bath, Adam D.G. Baxter-Jones, and Catherine M. Arnold

Distal radius fractures (DRF) are the most common fractures in women over the age of 50 years ( Edwards et al., 2006 ; Handol, Madhok, & Howe, 2006 ; Mulhall, Ahmed, Khan, & Masterson, 2002 ), with the incidence increasing from 9% at age 50–59 to 38% after age 80 ( Barrett-Conner, Weiss, McHorney

Restricted access

Kathryn C. Nesbit, Thubi A. Kolobe, Sandra H. Arnold, Susan B. Sisson, and Michael P. Anderson

Background:

The purpose of this study was to determine how proximal (home) and distal (neighborhood) environmental characteristics interact to influence obesity in early and middle adolescents.

Methods:

This was a descriptive, cross-sectional study using the 2007 National Survey of Children’s Health (NCSH). Participants were 39,542 children ages 11 to 17 years. Logistic regressions were used to examine the relationship between adolescent obesity and environmental factors, the relative strength of these factors, and the influence of age and gender.

Results:

Proximal environmental factors were stronger correlates of adolescent obesity than distal environmental factors. Sedentary behavior related to TV watching time at home was the strongest correlate of adolescent obesity overall (OR 1.13, 95% CI 1.11–1.15). Parks and playgrounds (OR 0.86, 95% CI 0.08–0.92), as well as recreation centers (OR 0.91, 95% CI 0.85–0.97) were significant distal environmental factor correlates. Girls and middle adolescents were at less risk for obesity than boys and early adolescents (OR 0.51, 95% CI 0.68–0.82; OR 0.75, 95% CI 0.68–0.96).

Conclusion:

The results of this study reveal the importance of proximal environmental characteristics on adolescent obesity relative to distal environmental characteristics. Obesity intervention strategies for adolescents should target sedentary behavior and opportunities for physical activity with a focus on early adolescents and boys.

Restricted access

Michele LeBlanc and Jesús Dapena

Equations that clarify the mechanical relationships between various parameter values and the velocity of the distal endpoint of a two-segment kinetic chain modeling the human arm were developed and analyzed. In particular, a single equation was presented that relates the distal endpoint velocity to the system’s angular momentum (as an indicator of muscular torque input), the ratio of the distal segment’s angular velocity to that of the proximal segment (the flail ratio), and the angle between the two segments (the configuration angle). These three system variables were analyzed to examine which values are best for creating a large value for the velocity of the distal endpoint. In addition, a sensitivity analysis was conducted to determine whether the relationships between the system values and the distal endpoint velocity were consistent for varying segment parameters. The relationships found were consistent for the various segment parameters. For any given values of the flail ratio and the configuration angle, the larger the value of the system angular momentum, the larger the value of the distal endpoint velocity. For any given values of the system angular momentum and the configuration angle, the larger the flail ratio, the larger the value of the distal endpoint velocity. For given values of the system angular momentum and the flail ratio, the optimal configuration angle that maximizes the distal endpoint velocity depends on the flail ratio value. While it may be impossible to generate simultaneously the combination of optimal parameter values determined, the knowledge of the relationships of these parameters with each other and with the distal endpoint velocity will aid in the search for an attainable optimal compromise.

Restricted access

Elisa S. Arch and Bretta L. Fylstra

The large, late-stance energy generated by the ankle is believed to be critical during gait. However, the distal foot absorbs/dissipates a considerable amount of energy during the same phase. Thus, the energy generated by the combined ankle–foot system is more modest, which raises questions regarding the necessity of such a large ankle power and the interplay between foot and ankle energetics. This study aimed to evaluate our conservation of energy hypothesis, which predicted if distal foot energy absorption/dissipation was reduced, then less energy would be generated at the ankle and thus the same combined ankle–foot energetics would be achieved. Motion analysis data were collected as healthy subjects walked under 2 conditions (Shoes, Footplate). In the Footplate condition, the shoe was replaced with a customized, rigid footplate with a rocker profile. In support of the hypothesis, there was significantly less positive ankle and less negative distal foot work with footplate use, resulting in very similar combined ankle–foot work between conditions. These findings suggest that there is an interplay between the energy generated by the ankle and absorbed by the foot. This interplay should be considered when designing orthotic and prosthetic ankle–foot systems and rehabilitation programs for individuals with weakened ankle muscles.

Restricted access

Alexander Synek, Yan Chevalier, Christian Schröder, Dieter H. Pahr, and Sebastian F. Baumbach

The variety of experimental setups used during in vitro testing of distal radius fracture treatments impairs interstudy comparison and might lead to contradictory results. Setups particularly differ with respect to their boundary conditions, but the influence on the experimental outcome is unknown. The aim of this biomechanical study was to investigate the effects of 2 common boundary conditions on the biomechanical properties of an extra-articular distal radius fracture treated using volar plate osteosynthesis. Uniaxial compression tests were performed on 10 synthetic radii that were randomized into a proximally constrained group (ProxConst) or proximally movable group (ProxMove). The load was applied distally through a ball joint to enable distal fragment rotation. A significantly larger (ProxConst vs ProxMove) stiffness (671.6 ± 118.9 N·mm−1 vs 259.6 ± 49.4 N·mm−1), elastic limit (186.2 ± 24.4 N vs 75.4 ± 20.2 N), and failure load (504.9 ± 142.5 N vs 200.7 ± 49.0 N) were found for the ProxConst group. The residual tilt did not differ significantly between the 2 groups. We concluded that the boundary conditions have a profound impact on the experimental outcome and should be considered more carefully in both study design and interstudy comparison.

Restricted access

Robert K. Zahn, Michael Jakubietz, Sönke Frey, Stefanie Doht, Alexander Sauer, and Rainer H. Meffert

Osteoporotic bone with poor mechanical capacity provides limited stability after fixation of ankle fractures. Stabilization with an implant providing increased fixation strength in osteoporotic bone could reduce failure rates of fixation and allow a more functional treatment. The purpose of this study was to evaluate a locking contoured plate for fixation of distal fibular fractures in comparison with a conventional contoured plate in an osteoporotic bone model. Eighty cylinders of osteoporotic bone surrogates were fixed with the two plates. We performed torque-to-failure and cyclic testing experiments using screws of different length with a Zwick/Roell testing machine. The locking system showed higher torque-to-failure and maximum torque levels as compared with the conventional plate in torque-to-failure experiments and torsional cyclic testing. The locking contoured plate provides improved fixation strength in the osteoporotic bone model. The locking system may be appropriate for fixation of distal fibular fractures, especially in osteoporotic bone with poor mechanical capacity.

Restricted access

Ryota Akagi, Soichiro Iwanuma, Satoru Hashizume, Hiroaki Kanehisa, Toshimasa Yanai, and Yasuo Kawakami

The purpose of this study was to investigate how the contraction-induced increase in distal biceps brachii tendon moment arm is related to that in elbow flexor muscle thickness, with a specific emphasis on the influence of the site-related differences in muscle thickness. The moment arm and muscle thickness were determined from sagittal and cross-sectional images, respectively, of the right arm obtained by magnetic resonance imaging of nine young men. The muscle thickness was measured at levels from the reference site (60% of the upper arm length from the acromial process of the scapula to the lateral epicondyle of the humerus) to 60 mm distal to it (every 10 mm; 7 measurement sites). At 80° of elbow flexion, the moment arm and muscle thickness were determined at rest and during 60% of maximal voluntary contraction (60%MVC) of isometric elbow flexion. Only the relative change from rest to 60%MVC in muscle thickness at the level 60 mm distal to the reference site correlated significantly with that of the moment arm. This result indicates that the contraction-induced increase in distal biceps brachii tendon moment arm is related to that in elbow flexor muscle thickness near the corresponding muscle-tendon junction.