The impact of differential knee laxity on brain function/structure and postural control

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Kyoungyoun Park-Braswell (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Randy Schmitz

Abstract: Greater anterior knee laxity (AKL) is known to be a significant predictor of anterior cruciate ligament (ACL) injury. Individuals with high AKL are known to have a proprioception deficit and exhibit compensatory movement patterns. The potential altered sensory information and associated movement strategies may lead to decreased functional stability, contributing to a higher risk of ACL injury. The brain has an essential role in integrating and processing sensory information in the course of stabilizing the joint. Our brain also has the ability to reorganize its function and structure (neuroplasticity) in response to sensory changes. However, it is still unknown how sensory information, associated with ACL loading in high AKL individuals, may affect brain function and structure. Decreased proprioception influenced by high knee laxity may also negatively impact postural stability. Postural stability is impacted by visual, vestibular, somatosensory input. It is broadly understood that individuals who are ACL deficient as well as hypermobile individuals joints have poor proprioception and postural control. It is suggested that poor proprioception negatively impacts postural control. Decreased proprioception due to greater knee laxity may thus diminish postural stability. However, the influence of greater AKL on postural control is not yet understood. Therefore, the primary purpose of this study is to determine the impact of high and low knee laxity on brain function and structure as well as dynamic postural stability. Healthy and physically active female college students volunteered for this study. Anterior knee laxity was measured to assign participants to either high (N=15) or low knee laxity (N=12) groups. Functional and structural brain data were obtained through magnetic resonance imaging (MRI). Functional MRI data were analyzed in order to compare brain activation differences during anterior knee joint loading between the two groups. Structural brain data were analyzed to identify differences in gray matter volume between the groups. Time to stabilization testing following a single-leg jump landing task was recorded in order to quantify dynamic postural stability. Independent t-tests contrasted dynamic postural stability between high and low to average laxity groups. fMRI data revealed that those with high knee laxity had significantly less activation in the left superior parietal lobe and right premotor cortex, and greater activation in the right cerebellum (Crus I and II) during anterior knee joint loading. The results suggest that individuals with greater knee laxity might experience a different awareness of their body’s position and may face challenges in preplanning and preprogramming potential movements. We also observed that the high knee laxity group had a nearly significant larger gray matter volume in BA6 (premotor cortex and supplementary motor area). We suggest that the larger gray matter volume in BA6 may be a response to the challenges in preplanning movements as a compensatory strategy. However, the time to stabilization test did not reveal any differences between the high and low to average laxity group. An advanced postural control test that separated the influence of somatosensation from other sensory input (visual and vestibular) may be recommended in order to identify the differences in dynamic postural control between groups. Our study reveals valuable information concerning possible functional and structural neuroplasticity associated with knee laxity. These results may help researchers better understand the influence of knee laxity on the sensorimotor system, especially the central integration and processing components, in individuals who are at increased risk of ACL injury.

Additional Information

Language: English
Date: 2020
ACL, Anterior Knee Laxity, Brain Function, Knee Laxity, Neuroplasticity
Knee $x Abnormalities
Joints $x Hypermobility
Anterior cruciate ligament

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