James A. Ashton-Miller

James K Richardson14
Edward M Wojtys7
Hogene Kim7
14James K Richardson
7Edward M Wojtys
7Hogene Kim
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To calculate the sample size for a research study it is important to take into account several aspects of the study design. In particular, one needs to take into account the hypotheses being tested, the study design, the sampling design, and the method to be used for the analysis. In this paper we propose a simple method to calculate sample size for(More)
BACKGROUND Knee joint morphology contributions to anterior cruciate ligament (ACL) loading are rarely considered in the injury prevention model. This may be problematic as the knee mechanical response may be influenced by these underlying morphological factors. The goal of the present study was to explore the relationship between posterior tibial slope(More)
BACKGROUND Cognitive impairment has been shown to predict falls risk in older adults. The ability to step accurately is necessary to safely traverse challenging terrain conditions such as uneven or slippery surfaces. However, it is unclear how well persons with cognitive impairment can step accurately to avoid such hazards and what specific aspects of(More)
OBJECTIVE To develop a three-dimensional computer model to predict levator ani muscle stretch during vaginal birth. METHODS Serial magnetic resonance images from a healthy nulliparous 34-year-old woman, published anatomic data, and engineering graphics software were used to construct a structural model of the levator ani muscles along with related passive(More)
OBJECTIVE To investigate the relationship among friction, applied torque, and axial push force on cylindrical handles. BACKGROUND We have earlier demonstrated that participants can exert greater contact force and torque in an "inward" movement of the hand about the long axis of a gripped cylinder (wrist flexion/forearm supination) than they can in an(More)
Pheasant and O'Neill's torque model (1975) was modified to account for grip force distributions. The modified model suggests that skin friction produced by twisting an object in the direction of fingertips causes flexion of the distal phalanges and increases grip force and, thus, torque. Twelve subjects grasped a cylindrical object with diameters of 45.1,(More)
Researchers are striving to understand the biomechanics of concussive injury that occur in the context of sport by using a number of methodologies. Animal models, video reconstruction, and helmet-based accelerometers have all been used, but have their limitations. The Head Impact Telemetry (HIT) System permits the real-time in vivo tracking of all impacts(More)
We hypothesize that the CNS detects a loss of balance by comparing outputs predicted by a nominal, forward internal model with actual sensory outputs. When the resulting control error signal reaches an anomalously large value, this control error anomaly (CEA) signals a loss of balance and precedes any observable compensatory response. To test this(More)
BACKGROUND We tested the hypothesis that impulsive compression, flexion and valgus knee moment loading during a simulated one-footed jump landing will significantly increase the peak relative strain in the anteromedial region of the anterior cruciate ligament compared with loading without the valgus moment. METHODS Ten cadaveric knees [mean (SD) age: 67.9(More)
Relatively few studies have examined how uneven surfaces affect human gait. To study this, along with the effects of advancing age and low light conditions, we measured step width and step time variability, as well as comfortable gait speed, in 12 healthy young women (YW) and 12 healthy older women (OW) as they walked at a comfortable speed along a 10-m(More)