Now showing 1 - 10 of 21
  • Publication
    Wearable sensing and mobile devices: the future of post-concussion monitoring?
    In the past decade, concussion has received large amounts of attention in public, medical and research circles. While our understanding of the nature and management of concussion has greatly improved, there are still major limitations which need to be addressed surrounding the identification of the injury, determining when an individual is safe to return to normal activity, and what factors may contribute to the development of post-concussion syndrome (PCS).The current model of concussion management involves a triage evaluation in the acute stage of injury, focusing on the classic signs and symptoms of concussion. Next, the clinician attempts to evaluate key components of cerebral function through clinical symptom evaluation, and traditional assessments of motor and neurocognitive function [1]. The development of the sports concussion assessment tool (SCAT) saw a massive leap forward in the strategies employed in the management of concussion, as it acknowledged the multifactorial nature of concussion, and provided a standardised means for clinicians to assess the many domains of cerebral function [2]. While these methods have demonstrated some promise in the acute stage, they are not designed for serial monitoring (particularly in instances where PCS develops) [3], and provide us with very little clinically relevant information that can assist clinicians in the return to learn/ sport/ performance process.
      415
  • Publication
    Lower Limb Interjoint Postural Coordination One Year after First-Time Lateral Ankle Sprain
    Introduction: Longitudinal analyses of participants with a history of lateral ankle sprain are lacking. This investigation combined measures of lower limb interjoint coordination and stabilometry to evaluate static unipedal stance with the eyes open (condition 1) and closed (condition 2) in a group of participants with chronic ankle instability (CAI) compared to lateral ankle sprain ‘‘copers’’ (both recruited 12 months after sustaining an acute first-time lateral ankle sprain) and a group of noninjured controls. Methods: Twenty-eight participants with CAI, 42 lateral ankle sprain ‘‘copers,’’ and 20 noninjured controls completed three 20-s singlelimb stance trials in conditions 1 and 2. An adjusted coefficient of multiple determination statistic was used to compare stance limb threedimensional kinematic data for similarity to establish patterns of interjoint coordination. The fractal dimension of the stance limb center of pressure path was also calculated. Results: Between-group analyses revealed that participants with CAI displayed notable increases in ankle–hip linked coordination compared with both lateral ankle sprain ‘‘copers’’ (j0.52 (1.05) vs 0.28 (0.9), P = 0.007) and controls (j0.52 (1.05) vs 0.63 (0.64), P = 0.006) in condition 1 and compared with controls only (0.62 (1.92) vs 0.1 (1.0) P = 0.002) in condition 2. Participants with CAI also exhibited a decrease in the fractal dimension of the center-of-pressure path during condition 2 compared with both controls and lateral ankle sprain ‘‘copers.’’ Conclusions: Participants with CAI present with a hip-dominant strategy of eyes-open and eyes-closed static unipedal stance. This coincided with reduced complexity of the stance limb center of pressure path in the eyes-closed condition.
      457Scopus© Citations 18
  • Publication
    Single-leg drop landing movement strategies 6 months following first-time acute lateral ankle sprain injury
    No research exists predicating a link between acute ankle sprain injury-affiliated movement patterns and those of chronic ankle instability (CAI) populations. The aim of the current study was to perform a biomechanical analysis of participants, 6 months after they sustained a first-time acute lateral ankle sprain (LAS) injury to establish this link. Fifty-seven participants with a 6-month history of first-time LAS and 20 noninjured participants completed a single-leg drop landing task on both limbs. Three-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment of force) data were acquired for the joints of the lower extremity, from 200 ms pre-initial contact (IC) to 200 ms post-IC. Individual joint stiffnesses and the peak magnitude of the vertical component of the ground reaction force (GRF) were also computed. LAS participants displayed increases in hip flexion and ankle inversion on their injured limb (P < 0.05); this coincided with a reduction in the net flexion-extension moment at the hip joint, with an increase in its stiffness (P < 0.05). There was no difference in the magnitude of the peak vertical GRF for either limb compared with controls. These results demonstrate that altered movement strategies persist in participants, 6 months following acute LAS, which may precipitate the onset of CAI.
      966Scopus© Citations 37
  • Publication
    Laboratory Measures of Postural Control During the Star Excursion Balance Test After Acute First-Time Lateral Ankle Sprain
    Context: No researchers, to our knowledge, have investigated the immediate postinjury-movement strategies associated with acute first-time lateral ankle sprain (LAS) as quantified by center of pressure (COP) and kinematic analyses during performance of the Star Excursion Balance Test (SEBT). Objective: To analyze the kinematic and COP patterns of a group with acute first-time LAS and a noninjured control group during performance of the SEBT. Design: Case-control study. Setting: University biomechanics laboratory. PATIENTS OR Other particpants: A total of 81 participants with acute first-time LAS (53 men, 28 women; age = 23.22 ± 4.93 years, height = 1.73 ± 0.09 m, mass = 75.72 ± 13.86 kg) and 19 noninjured controls (15 men, 4 women; age = 22.53 ± 1.68 years, height = 1.74 ± 0.08 m, mass = 71.55 ± 11.31 kg). Intervention: Participants performed the anterior (ANT), posterolateral (PL), and posteromedial (PM) reach directions of the SEBT. Main outcome Measure(s): We assessed 3-dimensional kinematics of the lower extremity joints and associated fractal dimension (FD) of the COP path during performance of the SEBT. Results: The LAS group had decreased normalized reach distances in the ANT, PL, and PM directions when compared with the control group on their injured (ANT: 58.16% ± 6.86% versus 64.86% ± 5.99%; PL: 85.64% ± 10.62% versus 101.14% ± 8.39%; PM: 94.89% ± 9.26% versus 107.29 ± 6.02%) and noninjured (ANT: 60.98% ± 6.74% versus 64.76% ± 5.02%; PL: 88.95% ± 11.45% versus 102.36% ± 8.53%; PM: 97.13% ± 8.76% versus 106.62% ± 5.78%) limbs (P < .01). This observation was associated with altered temporal sagittal-plane kinematic profiles throughout each reach attempt and at the point of maximum reach (P < .05). This result was associated with a reduced FD of the COP path for each reach direction on the injured limb only (P < .05). Conclusions: Acute first-time LAS was associated with bilateral deficits in postural control, as evidenced by the bilateral reduction in angular displacement of the lower extremity joints and reduced reach distances and FD of the COP path on the injured limb during performance of the SEBT.
      403Scopus© Citations 52
  • Publication
    Concussion is associated with altered preparatory postural adjustments during gait initiation
    Gait initiation is a useful surrogate measure of supraspinal motor control mechanisms but has never been evaluated in a cohort following concussion. The aim of this study was to quantify the preparatory postural adjustments (PPAs) of gait initiation (GI) in fifteen concussion patients (4 females, 11 males) in comparison to a group of fifteen age- and sex- matched controls. All participants completed variants of the GI task where their dominant and non-dominant limbs as the stepping and support limbs. Task performance was quantified using the centre of pressure (COP) trajectory of each foot (computed from a force plate) and the centre of mass (COM) trajectory (estimated from an inertial measurement unit placed on the sacrum). Concussed patients exhibited decreased COP excursion on their dominant foot, both when it was the stepping limb (sagittal plane: 9.71mm [95% CI: 8.14 to 11.27mm] vs 14.9mm [95%CI: 12.31 to 17.49mm]; frontal plane: 36.95mm [95% CI: 30.87 to 43.03mm] vs 54.24mm [95%CI: 46.99 to 61.50mm]) and when it was the support limb (sagittal plane: 10.43mm [95% CI: 8.73 to 12.13mm] vs 18.13mm [95%CI: 14.92 to 21.35mm]; frontal plane: 66.51mm [95% CI: 60.45 to 72.57mm] vs 88.43mm [95%CI: 78.53 to 98.32mm]). This was reflected in the trajectory of the COM, wherein concussion patients exhibited lower posterior displacement (19.67mm [95%CI: 19.65mm to 19.7mm]) compared with controls (23.62mm [95%CI: 23.6 to 23.64]). On this basis, we conclude that individuals with concussion display deficits during a GI task which are potentially indicative of supraspinal impairments in motor control.
      477Scopus© Citations 14
  • Publication
    Single-leg drop landing movement strategies in participants with chronic ankle instability compared with lateral ankle sprain 'copers'
    Individuals with CAI display alterations in hip joint kinematics and energetics during a unipodal landing task compared to LAS 'copers'. These alterations may be responsible for the increased risk of injury experienced by individuals with CAI during landing manoeuvres. Thus, clinicians must recognise the potential for joints proximal to the affected ankle to contribute to impaired function following an acute lateral ankle sprain injury and to develop rehabilitation protocols accordingly.
      1180Scopus© Citations 47
  • Publication
    Inter-joint coordination strategies during unilateral stance 6-months following first-time lateral ankle sprain
    Background: Longitudinal analyses of participants with a history of lateral ankle sprain are lacking. This investigation combined measures of inter-joint coordination and stabilometry to evaluate eyes-open (condition 1) and eyes-closed (condition 2) static unilateral stance performance in a group of participants, 6-months after they sustained an acute, first-time lateral ankle sprain in comparison to a control group. Methods: Sixty-nine participants with a 6-month history of first-time lateral ankle sprain and 20 non-injured controls completed three 20-second unilateral stance task trials in conditions 1 and 2. An adjusted coefficient of multiple determination statistic was used to compare stance limb 3-dimensional kinematic data for similarity in the aim of establishing patterns of lower-limb inter-joint coordination. The fractal dimension of the stance limb centre of pressure path was also calculated. Findings: Between-group analyses revealed significant differences in stance limb inter-joint coordination strategies for conditions 1 and 2, and in the fractal dimension of the centre-of-pressure path for condition 2 only. Injured participants displayed increases in ankle–hip linked coordination compared to controls in condition 1 (sagittal/frontal plane: 0.15 [0.14] vs 0.06 [0.04]; η2 = .19; sagittal/transverse plane: 0.14 [0.11] vs 0.09 [0.05]; η2 = 0.14) and condition 2 (sagittal/frontal plane: 0.15 [0.12] vs 0.08 [0.06]; η2 = 0.23), with an associated decrease in the fractal dimension of the centre-of-pressure path (injured limb: 1.23 [0.13] vs 1.36 [0.13]; η2 = 0.20). Interpretation: Participants with a 6-month history of first-time lateral ankle sprain exhibit a hip-dominant coordination strategy for static unilateral stance compared to non-injured controls.
      511Scopus© Citations 17
  • Publication
    Balance failure in single limb stance due to ankle sprain injury: An analysis of center of pressure using the fractal dimension method
    Instrumented postural control analysis plays an important role in evaluating the effects of injury on dynamic stability during balance tasks, and is often conveyed with measures based on the displacement of the center-of-pressure (COP) assessed with a force platform. However, the desired outcome of the task is frequently characterized by a loss of dynamic stability, secondary to injury. Typically, these failed trials are discarded during research investigations, with the potential loss of informative data pertaining to task success. The novelty of the present study is that COP characteristics of failed trials in injured participants are compared to successful trial data in another injured group, and a control group of participants, using the fractal dimension (FD) method. Three groups of participants attempted a task of eyes closed single limb stance (SLS): twenty-nine participants with acute ankle sprain successfully completed the task on their non-injured limb (successful injury group); twenty eight participants with acute ankle sprain failed their attempt on their injured limb (failed injury group); sixteen participants with no current injury successfully completed the task on their non-dominant limb (successful non-injured group). Between trial analyses of these groups revealed significant differences in COP trajectory FD (successful injury group: 1.58 ± 0.06; failed injury group: 1.54 ± 0.07; successful non-injured group: 1.64 ± 0.06) with a large effect size (0.27). These findings demonstrate that successful eyes-closed SLS is characterized by a larger FD of the COP path when compared to failed trials, and that injury causes a decrease in COP path FD.
      687Scopus© Citations 26
  • Publication
    Lower extremity function during gait in participants with first time acute lateral ankle sprain compared to controls
    Laboratory analyses of chronic ankle instability populations during gait have elucidated a number of anomalous movement patterns. No current research exists analysing these movement patterns in a group in the acute phase of lateral ankle sprain (LAS) injury. It is possible that participants with an acute LAS display movement patterns continuous with their chronically impaired counterparts. Sixty eight participants with acute LAS and nineteen non-injured participants completed five gait trials. 3D lower extremity temporal kinematic and kinetic data were collected from 200ms pre- to 200ms post-heel strike (period 1) and from 200ms pre- to 200ms post-toe off (period 2). During period 1, the LAS group displayed increased knee flexion with increased net extensor pattern at the knee joint, increased ankle inversion with a greater inversion moment, and reduced ankle plantar flexion, compared to the non-injured control group. During period 2, the LAS group displayed decreased hip extension with a decrease in the flexor moment at the hip, and decreased ankle plantar flexion with a decrease in the net plantar flexion moment, compared to the non-injured control group. These results indicate that participants with acute LAS display coordination strategies which may play a role in the onset of chronicity or recovery.
      899Scopus© Citations 26
  • Publication
    Quantification of postural control deficits in patients with recent concussion: An inertial-sensor based approach
    Background: The aim of this study was to quantify postural control ability in a group with concussion compared with a healthy control group. Method: Fifteen concussion patients (4 females, 11 males) and a group of fifteen age- and sex-matched controls were recruited. Participants were tested during the performance of the three stance variants (bilateral, tandem and unilateral) of the balance error scoring system standing on a force place, while wearing an inertial measurement unit placed at the posterior aspect of the sacrum. Findings: The area of postural sway was computed using the force-plate and the '95% ellipsoid volume of sway' was computed from the accelerometer data. Concussed patients exhibited increased sway area (1513 mm2 [95% CI: 935 to 2091 mm2] vs 646 mm2 [95% CI: 519 to 772 mm2]; p = 0.02) and sway volume (9.46 m3 s− 6 [95% CI: 8.02 to 19.94 m3 s− 6] vs 2.68 m3 s− 6 [95% CI: 1.81 to 3.55 m3 s− 6]; p = 0.01) in the bilateral stance position of the balance error scoring system. The sway volume metric also had excellent accuracy in identifying task 'errors' (tandem stance: 91% accuracy [95% CI: 85–96%], p < 0.001; unilateral stance: 91% accuracy [95% CI: 86–96%], p < 0.001). Interpretation: Individuals with concussion display increased postural sway during bilateral stance. The sway volume that was calculated from the accelerometer data not only differentiated a group with concussion from a healthy control group, but successfully identified when task errors had occurred. This may be of value in the development of a pitch-side assessment system for concussion.
      813Scopus© Citations 37