Spacecraft Dynamics

Kane, T. R.; Likins, P. W.; Levinson, David A.; Huston, Ronald L.

doi:10.1115/1.3167078

Cited by 232 publications

(77 citation statements)

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“…Once the displacement trajectories for a minimum of three noncolinear points were known, the bone's complete 3D rotation matrix and translation trajectory were calculated [21,43]. The rotation matrix was simplified to three Cardan rotation angles using an xyz body-fixed rotation Quantitative J-sign* (present) 7 0…”

Section: Methodsmentioning

confidence: 99%

Q-angle and J-sign: Indicative of Maltracking Subgroups in Patellofemoral Pain

Sheehan

Derasari

Fine

et al. 2010

Clinical Orthopaedics &Amp; Related Research

101

103

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Mechanical factors related to patellofemoral pain syndrome and maltracking are poorly understood. Clinically, the Q-angle, J-sign, and lateral hypermobility commonly are used to evaluate patellar maltracking. However, these measures have yet to be correlated to specific three-dimensional patellofemoral displacements and rotations. Thus, we tested the hypotheses that increased Q-angle, lateral hypermobility, and J-sign correlate with three-dimensional patellofemoral displacements and rotations. We also determined whether multiple maltracking patterns can be discriminated, based on patellofemoral displacements and rotations. Three-dimensional patellofemoral motion data were acquired during active extensionflexion using dynamic MRI in 30 knees diagnosed with patellofemoral pain and at least one clinical sign of patellar maltracking (Q-angle, lateral hypermobility, or J-sign) and in 37 asymptomatic knees. Although the Q-angle is assumed to indicate lateral patellar subluxation, our data supported a correlation between the Q-angle and medial, not lateral, patellar displacement. We identified two distinct maltracking groups based on patellofemoral lateral-medial displacement, but the same groups could not be discriminated based on standard clinical measures (eg, Q-angle, lateral hypermobility, and J-sign). A more precise definition of abnormal three-dimensional patellofemoral motion, including identifying subgroups in the patellofemoral pain population, may allow more targeted and effective treatments.

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Section: Methodsmentioning

confidence: 99%

Q-angle and J-sign: Indicative of Maltracking Subgroups in Patellofemoral Pain

Sheehan

Derasari

Fine

et al. 2010

Clinical Orthopaedics &Amp; Related Research

101

103

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“…For data presentation, the orientation matrices were simplified to orientation angles (Fig. 4) based on an xyz body-fixed rotation sequence (22,23).…”

Section: Methodsmentioning

confidence: 99%

Precise 3D skeletal kinematics using fast phase contrast magnetic resonance imaging

Rebmann

Sheehan

2003

Magnetic Resonance Imaging

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PurposeTo examine the precision of cine‐phase contrast (PC) magnetic resonance imaging (MRI) techniques as applied to the quantification of three‐dimensional knee joint kinematics.Materials and MethodsThe knee joints of eight healthy volunteers were studied using three different dynamic, PC MRI protocols: cine‐PC (one average), cine‐PC (two averages), and cine‐PC with segmented phase encoding (fast‐PC).ResultsFast‐PC has comparable precision, shorter scan times, and improved subject interexam variability (SIEV) compared to cine‐PC (two averages). Further, cine‐PC (one average) has low precision and high SIEV, making fast‐PC the preferred method of data acquisition. Specifically, the precision of fast‐PC MRI in measuring knee joint kinematics ranged from 0.22°–1.16°.ConclusionA cine‐PC MRI technique utilizing segmented phase encoding (fast‐PC MRI) acquires dynamic data at a faster rate than other PC imaging protocols, without compromising data precision. Being able to acquire precise 3D kinematics with shorter imaging times is critical if we are to use this technique to advance ongoing research in musculoskeletal kinematics. J. Magn. Reson. Imaging 2003;17:206–213. © 2003 Wiley‐Liss, Inc.

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“…In the development presented in the subsequent sections, the right-handed Cartesian coordinate systems oxyz and O 2 x 2 y 2 z 2 are used as an inertial reference system and a body-fixed reference system, respectively; the space-three-angles x-y-z defined in the Ref. [16], are used as the orientation angles of involved bodies.…”

Section: General Theorems and Steps Of The Proposed Methodsmentioning

confidence: 99%

Discrete time transfer matrix method for dynamics of multibody system with flexible beams moving in space

et al. 2012

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In this paper, by defining new state vectors and developing new transfer matrices of various elements moving in space, the discrete time transfer matrix method of multi-rigid-flexible-body system is expanded to study the dynamics of multibody system with flexible beams moving in space. Formulations and numerical example of a rigidflexible-body three pendulums system moving in space are given to validate the method. Using the new method to study the dynamics of multi-rigid-flexible-body system moving in space, the global dynamics equations of system are not needed, the orders of involved matrices of the system are very low and the computational speed is high, irrespective of the size of the system. The new method is simple, straightforward, practical, and provides a powerful tool for multi-rigid-flexible-body system dynamics.

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Spacecraft Dynamics

Cited by 232 publications

References 0 publications

Q-angle and J-sign: Indicative of Maltracking Subgroups in Patellofemoral Pain

Q-angle and J-sign: Indicative of Maltracking Subgroups in Patellofemoral Pain

Precise 3D skeletal kinematics using fast phase contrast magnetic resonance imaging

Discrete time transfer matrix method for dynamics of multibody system with flexible beams moving in space

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