Now showing 1 - 10 of 26
  • Publication
    Acute ankle sprain injury alters kinematic and centre of pressure measures of postural control during single limb stance
    Background: Upright single-limb stance (SLS) is maintained via integration of visual, vestibular and somatosensory afferents. The presence of redundancies between these afferents allows the sensorimotor system to simplify a specific task within a number of strategies. Musculoskeletal injury challenges the somatosensory system to reweight distorted sensory afferents. No current investigation has supplemented kinetic analysis of eyes-open and eyes-closed SLS tasks with a kinematic profile of lower limb postural orientation in an acute lateral ankle sprain (LAS) group to assess the adaptive capacity of the sensorimotor system to injury. Objective: To compare centre of pressure (COP) and lower limb postural orientation characteristics of participants with acute LAS to non-injured participants during a SLS task. Design Cross-sectional: Setting University biomechanics laboratory. Participants: 66 participants with acute LAS completed a task of eyes-open SLS on their injured and non-injured limbs (task 1). 23 of these participants successfully completed the SLS task with their eyes closed (task 2). A non-injured control group of nineteen participants completed task 1, with 16 completing task 2. Main outcome measures: 3D kinematics of the hip, knee and ankle joints as well as associated fractal dimension (FD) of the COP path. Results: Between trial analyses of groups revealed significant differences in lower limb kinematics and FD of the COP path for task 2. Post-hoc testing revealed that non-injured control group bilaterally assumed a position of greater hip flexion compared to LAS participants (injured limb=7.41±6.1◦ vs 1.44±4.8◦; non-injured limb=9.59±8.5◦ vs 2.16±5.6◦), with a corollary of greater FD of the COP path (injured limb=1.39±0.16 vs 1.25±0.14; non-injured limb=1.37±0.21 vs 1.23±0.14). Conclusion: Acute LAS causes bilateral impairment in postural control strategies.
  • Publication
    Is there a role for Placental Volume, Vasculature and Calcification in monitoring Post-term Pregnancies?
    Objectives: This study aims to assess if three dimensional power Doppler (3DPD) ultrasound of the placenta, evaluating placental volume, vascularisation, and blood flow in post-term pregnancies differs from normal. It also examines whether computer analysis identifies the increased calcification normally present in the placenta after 40 weeks. Methods: This was a prospective cohort study involving 50 women with post-term pregnancies. Gestational age (GA) ranged from 40-41+6 weeks gestation. 3DPD ultrasound was used to evaluate placental volume, vascularisation index (VI), flow index (FI) and vascularisation-flow index (VFI). Following each scan the percentage of calcification was also calculated, by computer analysis. Results were compared with previously determined normal values (36-40 weeks gestation) and correlated with Doppler values and placental histology. Results: Results showed that placental volume, VI, FI and VFI are not influenced by GA when the pregnancy has advanced beyond 40 weeks and that values are similar between post-term pregnancies and normal pregnancies between 36 and 40 weeks. Placental volume was seen to decrease in post-term pregnancies as the mean UtA PI increased (P=0.047).  FI was reduced in cases where chorangiosis was found at histology (P=0.033), identifying the increased vessel number associated with these cases. Computer analysis of placental calcification identified the increased calcification expected after 40 weeks, and also showed that calcification continues to increase between 40 and 42 weeks (P=0.029). Conclusion: This study suggests that 3DPD placental assessment may provide additional information, assisting clinicians in decision making in post-term pregnancies.
  • Publication
    Best single slice location to measure visceral adipose tissue on paediatric CT scans and the relations between anthropometric measurements, gender and VAT volume in children
    (British Institute of Radiology, 2015-09-21) ; ;
    Objective: Visceral adipose tissue (VAT) is a significant risk factor for obesity-related metabolic diseases. This study investigates (1) the best single CT slice location for predicting total abdominal VAT volume in paediatrics and (2) the relationship between waist circumference (WC), sagittal diameter (SD), gender and VAT volume. Methods: A random sample of 130 paediatric abdomen CT scans, stratified according to age and gender, was collected. Three readers measured VAT area at each intervertebral level between T12 and S1 using ImageJ analysis (National Institute of Health, Bethesda, MD) software by thresholding −190 to −30 HU and manually segmenting VAT. Single-slice VAT measurements were correlated with total VAT volume to identify the most representative slice. WC and SD were measured at L3–L4 and L4–L5 slices, respectively. Regression analysis was used to evaluate WC, SD and gender as VAT volume predictors. Results: Interviewer and intraviewer reliability were excellent (intraclass correlation coefficient = 0.99). Although VAT measured at multiple slices correlated strongly with abdominal VAT, only one slice in females at L2–L3 and two slices in males at L1–L2 and L5–S1 were strongly correlated across all age groups. Linear regression analysis showed that WC was strongly correlated with VAT volume (beta = 0.970, p < 0.001). Conclusion: Single-slice VAT measurements are highly reproducible. Measurements performed at L2–L3 in females and L1–L2 or L5–S1 in males were most representative of VAT. WC is indicative of VAT. Advances in knowledge: VAT should be measured at L2–L3 in female children and at either L1–L2 or L5–S1 in males. WC is a strong indicator of VAT in children.
      160Scopus© Citations 16
  • Publication
    Single-leg drop landing motor control strategies following acute ankle sprain injury
    No research currently exists investigating the effect of acute injury on single-limb landing strategies. The aim of the current study was to analyse the coordination strategies of participants in the acute phase of lateral ankle sprain (LAS) injury. Thirty-seven participants with acute, first-time, LAS and nineteen uninjured participants completed a single-leg drop landing task (DL) on both limbs. 3-dimensional kinematic (angular displacement) and sagittal plane kinetic (moment of force) data were acquired for the joints of the lower extremity, from 200ms pre-initial contact (IC) to 200ms post IC. The peak magnitude of the vertical component of the ground reaction force (GRF) was also computed. Injured participants displayed a bilateral increase in hip flexion, with altered transverse plane kinematic profiles at the knee and ankle for both limbs (p < 0.05). This coincided with a reduction in the net supporting flexor moment of the lower extremity (p < 0.05) and magnitude of the peak vertical GRF for the injured limb (21.82 ± 2.44 N/kg vs 24.09 ± 2.77 N/kg; p = 0.013) in injured participants compared to control participants. These results demonstrate that compensatory movement strategies are utilized by participants with acute LAS to successfully reduce the impact forces of landing.
      950Scopus© Citations 33
  • 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.
      889Scopus© Citations 37
  • 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.
      387Scopus© Citations 12
  • 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.
      535Scopus© Citations 25
  • 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.
      325Scopus© Citations 45
  • Publication
    3D Power Doppler ultrasound and computerised placental assessment in normal pregnancy
    Background: In recent years there have been significant developments in the use of 3D Power Doppler (3DPD) imaging and quantitative 3DPD histogram analysis to estimate both placental volume and intra-placental vasculature. This study aims to determine if placental volume, vascularisation and blood flow are correlated with gestational age in normal pregnancy. It also examines whether or not a new software method for analysis of percentage calcification (the ‘placentometer’) correlates well with gestation. Material and method: This was a prospective cohort study of 250 women with normal pregnancies (12 + 6 to 39 + 5 weeks gestation). 3DPD ultrasound was used to evaluate placental volume, vascularisation index (VI), flow index (FI) and vascularisation-flow index (VFI). Placental volume (calculated at 35–40 weeks gestation), was correlated with birth weight. Following each scan the percentage of calcification was also calculated using the placentometer. Results: Placental volume correlated significantly with gestational age: 66.676 + 0.623 × GA (P < 0.001). No significant change with gestation was noted in VI, FI and VFI (VI: P = 0.199, FI: P = 0.299, VFI: P = 0.557). Software analysis of the percentage of calcification, demonstrated the expected increase in calcification as gestation increased: −4.605 + 0.032 × GA (P < 0.001). From 35 to 40 weeks gestation volume was related to birth weight (P < 0.01). Conclusion: This study shows that in normal low-risk pregnancy placental volume increases with gestational age, whereas vascularisation and blood flow are independent of gestation. Placental volume in late pregnancy is related to birth weight. Software analysis of the percentage of calcification demonstrates an increase with advancing gestation.
      319Scopus© Citations 5
  • Publication
    Gait Biomechanics in Participants, Six Months after First-Time Lateral Ankle Sprain
    No research currently exists predicating a link between the injury-affiliated sensorimotor deficits of acute ankle sprain and those of chronic ankle instability during gait. This analysis evaluates participants with a 6-month history of ankle sprain injury to affirm this link. 69 participants with a 6-month history of acute first-time lateral ankle sprain were divided into subgroups (‘chronic ankle instability’ and 'coper') based on their self-reported disability and compared to 20 non-injured participants during a gait task. Lower extremity kinematic and kinetic data were collected from 200 ms pre- to 200 ms post-heel strike (period 1) and from 200 ms pre- to 200 ms post-toe off (period 2). The ‘chronic ankle instability’ subgroup (who reported greater disability) displayed increased knee flexion during period 1. During period 2, this subgroup exhibited greater total displacement at their ankle joint and greater extensor dominance at their knee. That many of these features are present, both in individuals with acute ankle sprain and those with chronic ankle instability may advocate a link between acute deficits and long-term outcome. Clinicians must be aware that the sensorimotor deficits of ankle sprain may persevere beyond the acute stage of injury and be cognizant of the capacity for impairments to pervade proximally.
      521Scopus© Citations 8