UNIVERSITY OF NORTH CAROLINA AT GREENSBORO
Grant: $155,102 - National Institutes of Health - Sep. 18, 2009
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Award Description: Hormone Mediated Knee Joint Laxity and Neuromichanics The primary aim of the parent grant is to determine the effects of greater absolute (ABSAKL) and cyclic (CYCAKL) changes in anterior knee joint laxity (AKL) on knee joint neuromechanics (muscle activation, joint motions and torques) during weight bearing. Our central hypothesis is that greater ABSAKL and CYCAKL would independently and in combination predict greater anterior tibial translation (ATT) during the transition from non-weight bearing to weight bearing, and greater ?functional valgus collapse? of the knee during a single leg weight bearing perturbation and a double leg drop landing. Although we originally proposed to only examine AKL relative to weight bearing knee joint function, increasing evidence over the past 3 years indicates that greater magnitudes of genu recurvatum (GR) and general joint laxity (GJL) are also associated with greater risk of ACL injury. More recently, greater transverse (internal-external rotation) and frontal (varus-valgus) plane knee laxity has also received attention for its impact on dynamic joint stability. This motivated us to also track GR and GJL on a daily basis during the 2 month tracking phase (daily collection of VVLAX and IERLAX was not possible due to time and equipment limitations) and to consider the impact of all 5 laxity variables on knee joint neuromechanics (i.e. do they represent same or different risk factors as AKL?). Preliminary results reveal that the relationships between joint laxity and knee joint neuromechanics are substantially more complex than AKL alone, and indicate the need to consider a more comprehensive laxity profile. Therefore, the purpose of this administrative supplement is to substantially expand our statistical analyses (thus understanding) of these laxity profiles and their effect on the neuromechanical profiles during landing and functional perturbations so that we can achieve greater scientific power within the peer-reviewed scope of Specific Aim #1 of the parent grant. Specifically, the administrative supplement will achieve the following objectives: Objective 1: To identify through advance statistical methods individual laxity profiles (comprised of AKL, GR, GJL and IER and VV laxity values) and individual landing profiles and lower extremity perturbation profiles (comprised of joint motions and forces during the drop landing and single leg perturbation) and determine the laxity profile(s) that are most predictive of at risk knee biomechanical profiles. Objective 2: To better understand the underlying factors leading to laxity profiles identified in Objective 1. Expanding our analyses within the scope of Specific Aim #1 will greatly enhance the value and scientific quality of the project, as it will allow us to describe a more complete laxity ?profile? that leads to at risk landing and perturbation response strategies, and the underlying anatomical factors that may lead to a particular laxity profile, thus knee joint biomechanical profile during a landing or sudden perturbation. Understanding these complex relationships will lead to further development of the knee injury model and thus more targeted and tailored interventions to reduce injury risk. Upon completion of this work, we anticipate that the next logical step will be to examine the impact of these laxity profiles and landing strategies on ACL injury risk using a prospective study design. This is a significant step forward, as it will be the first to directly connect anatomy, laxity profiles, at risk knee joint biomechanical strategies (profiles) and ACL injury risk. Advancing our knowledge of the underlying pathophysiological mechanism(s) of at risk movement strategies will allow us to better identify and target those at greater risk through appropriate screening and prevention measures.
Project Description: Award was received on 9/18/09 (9 days ago). Award was received on 9/18/09 (9 days ago). As such, we are still in the process of hiring the required support personnel. We have filled the graduate assistant position and are currently interviewing applicants for the quantitative methodologist so that we can begin to conduct the planned analyses. Our expectation is that the extensive fine grained analyses of laxity and neuromechanics will allow us to model the relationships among these variables and lead to further development of the knee injury model and thus lead to targeted and tailored interventions to reduce the risk for knee injury across popular athletic endeavors. In addition, we feel that the statistical support we can make important methodological advances in how these data are analyzed which can provide new insight into knee injury. Our goal is to make responsible use of this extensive data to both answer substantive questions about knee laxity and movement profiles, AND to advance the statistical methodology in the field beyond the current reliance on rather simplistic measures of knee movement and forces (e.g. initial, peak and excursion values).
Jobs Summary: At this point, we have hired a full time graduate assistant and are in the process of interviewing for the position of statistician. The graduate research assistant is a doctoral student who will assist with exportation of the biomechanical data as non-normalized continuous data. She will assist the quantitative methodologist in manipulating and formatting the data for the planned analyses. She will also assist Dr. Shultz with presentation and publication development. We anticipate hiring the statistician within the coming week. Given the reduced budget, this will be a masters degree prepared quantitative methodologist (QM) who will work under the direction of Drs Shultz, Schmitz and Dudley to plan and conduct statistical analyses in support of both the substantive and methodological foci of this supplement. This individual will also assist with moving forward with additional manuscripts planned for the project, pursue methodological papers on the use of the multivariate techniques we have proposed, and to refine and extend these techniques for use in future applications for funding in support of our overall research agenda. (Total jobs reported: 0)
Project Status: Not Started
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