Medio-lateral Knee Fluency in ACL-Injured Athletes During Dynamic Movement Trials
Advisor:Hewett, Timothy E.
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Biomedical Engineering Honors Theses; 2015
Correction of lower-extremity neuromuscular impairments after anterior cruciate ligament (ACL) injury is vital to rehabilitation and successful return to sport. Frontal plane knee control during the landing phase of dynamic movements is a common measure of lower-extremity neuromuscular control. Limb asymmetries may indicate knee control deficits or incomplete recovery from injury, which can predispose injured athletes to additional knee injury and associated morbidities (24, 36). Therefore, the purpose of this study was to determine the effects of ACL injury on bilateral knee biomechanics during dynamic movement tests. This study utilized two-dimensional (2D) frontal plane video as a more spatially, financially, and clinically translatable alternative to three-dimensional motion capture technology. 2D frontal plane video of single leg drop (SLD), cross over drop (COD), and drop vertical jump (DVJ) dynamic movement trials were analyzed for eleven ACL-injured athletes (21.1±12.9 years; 2 male, 9 female). Intersecting vertical and horizontal lines, generated in ImageJ software, were used to define and track the knee joint center for 500 milliseconds after landing. Knee velocity was calculated from positional values and analyzed in MATLAB to determine normal fluency (FN), defined as the number of times per second knee velocity changed direction. The inverse of this calculation, analytical fluency (FA), was used to associate larger numerical values to more fluent movement. FA for involved limbs was significantly lower than uninvolved limbs for SLD trials (p<0.001) but not for COD (p=0.788) or DVJ trials (p=0.136). Furthermore, a relationship for the involved limb was established for FA such that: SLD < COD < DVJ. A significant asymmetry in the medio-lateral range of the knee joint center position was observed in SLD trials (p=0.003) with a trend towards a similar asymmetry in COD (p=0.0596) but not DVJ trials (p=0.1575). Decreased FA of involved limbs, indicative of knee control deficits, is consistent with previous studies. Asymmetries in the medio-lateral range of the knee joint center may indicate adverse landing strategies in the involved limb. Furthermore, modeling the medio-lateral knee velocity during landing as a damped harmonic oscillator, knee fluency may be related to Euclidean jolt, a descriptor of the rate-of-change of force. Analytical relationships between limbs suggest greater jolt for involved than uninvolved limbs in SLD trials. Jolt, implicated in musculoskeletal injury, serves to further contextualize, and mathematically support, the clinical relevance of knee fluency. Elucidation of landing strategies and force dissipation, quantified by fluency and jolt, in healthy limbs could provide new approaches for ACL-injury rehabilitation and endpoint determinations.
2nd Place - Denman Undergraduate Research Forum, Health Professions - Clinical Division
Academic Major: Biomedical Engineering
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