Dynamic Postural Stability and Cognitive Loading in individual with and without ACLR: Insights from Comparative Studies
Creators: Labban, Wasim
Publisher: name: University of Alberta Library
Year: 2024

<p>Background: Postural stability is the ability to maintain posture against gravity while responding to internal or external perturbations. Evidence suggests that poor postural stability is a significant risk factor for sustaining non-contact anterior cruciate ligament (ACL) injuries. Following ACL reconstruction (ACLR), individuals often exhibit residual postural stability deficits, which can impede their recovery and increase the risk of re-injury. Dynamic postural stability is critical for movement control and injury prevention after ACLR. </p>

<p>Objective: This dissertation aims to comprehensively explore kinetic measurements and postural stability in individuals following ACLR through four original research papers. The primary objectives include (1) describing current approaches and methodological reporting for kinetic measurements post-ACLR, (2) identifying force plate parameters that distinguish post-ACLR individuals from Healthy Controls and are responsive to changes over time in post-ACLR individuals during countermovement jumps (CMJ) and/or drop jumps (DJ), (3) comparing dynamic postural stability between post-ACLR individuals and Healthy Controls, and (4) examining the dual-task effect on postural stability in these groups.</p>

<p>Methods: This dissertation employed a stepwise research approach, beginning with a scoping review of 158 original papers to identify methodological approaches in kinetic measurement systems for ACLR individuals. A systematic review and meta-analysis of 33 studies was conducted to pinpoint discriminative and responsive force-plate parameters during CMJ and drop jumps. An investigation was then conducted into dynamic postural stability differences, including sex-specific differences, between 21 ACLR individuals (10 females) and 20 Healthy Controls (10 females). Finally, the dual-task effect on postural stability was examined using the Stroop task in both ACLR and Healthy Control groups.</p>

<p>Results: The scoping review revealed a significant increase over the last decade in the evaluation of kinetic outcomes in ACLR populations, though with marked heterogeneity in methodologies, hindering comparisons across studies, and suggested methodological reporting considerations. The systematic review and meta-analysis included 1185 individuals with ACLR (50.38%) and 1167 Healthy Controls (49.62%), categorized data into single-leg CMJ, double-leg CMJ, single-leg DJ, and double-leg DJ. The review identified reduced jump height in single-leg (MD = -3.13; p &lt; 0.01; 95% CI: [-4.12, -2.15]) and double-leg (MD = -4.24; p &lt; 0.01; 95% CI: [-5.14, -3.34]) CMJs among ACLR individuals. Concentric impulse and eccentric/concentric impulse asymmetry could distinguish ACLR (MD = 3.42; p &lt; 0.01; 95% CI: [2.19, 4.64]) from non-ACLR individuals (MD = 5.82; p &lt; 0.01; 95% CI: [4.80, 6.80]). In double-leg DJs, peak vertical ground reaction forces were lower in the involved side (MD = -0.10; p = 0.03; 95% CI: [-0.18, -0.01]) and higher in the uninvolved side (MD = 0.15; p &lt; 0.01; 95% CI: [0.10, 0.20]) compared to controls, showing significant changes between 6 months and 3 years post-ACLR.<br>
Dynamic postural stability assessments showed higher combined resultant vector time to stabilization (RVTTS-C) and higher vertical time to stabilization in the operated leg (VTTS-op) among individuals post-ACLR compared to Healthy Controls (p=0.03, p=0.02 respectively). Males with ACLR exhibited higher combined vertical time to stabilization (VTTS-C) and VTTS-op values than females post-ACLR (p=0.03, p&lt;0.01 respectively) and higher VTTS-op compared to healthy males (p=0.03). No differences in postural stability indices (PSI) were found between groups. Under dual-task conditions, both groups showed longer RVTTS-C, with the ACLR group showing a 0.61±0.14 second increase (p&lt;0.01) and Healthy Controls showing a 0.98±0.12 second increase (p&lt;0.01). Significant increases in PSI variables under dual-task conditions were observed in the ACLR group for MLSI-C (0.05±0.02, p=0.01) and DPSI-C (0.06±0.02, p=0.03), and in Healthy Controls for APSI-C (0.05±0.01, p=0.02), MLSI-C (0.07±0.01, p&lt;0.01), DPSI-C (0.08±0.01, p&lt;0.01), and matched MLSI-op (0.08±0.03, p=0.02). The Stroop effect on RVTTS-C was higher among Healthy Controls by 0.37±0.76 seconds (p=0.03), with no other significant differences between groups. </p>

<p>Conclusion: This dissertation underscores the importance of dynamic postural stability assessment in individuals with ACLR, offering practical recommendations that may improve assessment protocols and inform tailored rehabilitation strategies. The research highlights the need for standardized assessment methods, and considering the integration of cognitive loading in the assessment and treatment of people post-ACLR</p>