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Dive into the research topics where Philip Dubois is active.

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Featured researches published by Philip Dubois.


Physical Therapy | 2007

Plantar Fasciitis: Are Pain and Fascial Thickness Associated With Arch Shape and Loading?

Scott C. Wearing; James E. Smeathers; Patrick M. Sullivan; Bede Yates; Stephen R. Urry; Philip Dubois

Background and Purpose: Although plantar fascial thickening is a sonographic criterion for the diagnosis of plantar fasciitis, the effect of local loading and structural factors on fascial morphology are unknown. The purposes of this study were to compare sonographic measures of fascial thickness and radiographic measures of arch shape and regional loading of the foot during gait in individuals with and without unilateral plantar fasciitis and to investigate potential relationships between these loading and structural factors and the morphology of the plantar fascia in individuals with and without heel pain. Subjects: The participants were 10 subjects with unilateral plantar fasciitis and 10 matched asymptomatic controls. Methods: Heel pain on weight bearing was measured by a visual analog scale. Fascial thickness and static arch angle were determined from bilateral sagittal sonograms and weight-bearing lateral foot roentgenograms. Regional plantar loading was estimated from a pressure plate. Results: On average, the plantar fascia of the symptomatic limb was thicker than the plantar fascia of the asymptomatic limb (6.1±1.4 mm versus 4.2±0.5 mm), which, in turn, was thicker than the fascia of the matched control limbs (3.4±0.5 mm and 3.5±0.6 mm). Pain was correlated with fascial thickness, arch angle, and midfoot loading in the symptomatic foot. Fascial thickness, in turn, was positively correlated with arch angle in symptomatic and asymptomatic feet and with peak regional loading of the midfoot in the symptomatic limb. Discussion and Conclusion: The findings indicate that fascial thickness and pain in plantar fasciitis are associated with the regional loading and static shape of the arch.


Medicine and Science in Sports and Exercise | 2004

Sagittal movement of the medial longitudinal arch is unchanged in plantar fasciitis.

Scott C. Wearing; James E. Smeathers; Bede Yates; Patrick M. Sullivan; Stephen R. Urry; Philip Dubois

BACKGROUND Although a lowered medial longitudinal arch has been cited as a causal factor in plantar fasciitis, there is little experimental evidence linking arch motion to the pathogenesis of the condition. This study investigated the sagittal movement of the arch in subjects with and without plantar fasciitis during gait. METHODS Digital fluoroscopy was used to acquire dynamic lateral radiographs from 10 subjects with unilateral plantar fasciitis and 10 matched control subjects. The arch angle and the first metatarsophalangeal joint angle were digitized and their respective maxima recorded. Sagittal movement of the arch was defined as the angular change between heel strike and the maximum arch angle observed during the stance phase of gait. The thickness of the proximal plantar fascia was determined from sagittal sonograms of both feet. ANOVA models were used to identify differences between limbs with respect to each dependent variable. Relationships between arch movement and fascial thickness were investigated using correlations. RESULTS There was no significant difference in either the movement or maximum arch angle between limbs. However, subjects with plantar fasciitis were found to have a larger metatarsophalangeal joint angle than controls (P < 0.05). Whereas the symptomatic and asymptomatic plantar fascia were thicker than those of control feet (P < 0.05), significant correlations were noted between fascial thickness and peak arch and metatarsophalangeal joint angles (P < 0.05) in the symptomatic limb only. CONCLUSIONS Neither abnormal shape nor movement of the arch are associated with chronic plantar fasciitis. However, arch mechanics may influence the severity of plantar fasciitis, once the condition is present. Digital flexion, in contrast, has a protective role in what might be a bilateral disease process.


Clinical Biomechanics | 2009

Bulk compressive properties of the heel fat pad during walking: A pilot investigation in plantar heel pain

Scott C. Wearing; James E. Smeathers; Bede Yates; Stephen R. Urry; Philip Dubois

BACKGROUND Altered mechanical properties of the heel pad have been implicated in the development of plantar heel pain. However, the in vivo properties of the heel pad during gait remain largely unexplored in this cohort. The aim of the current study was to characterise the bulk compressive properties of the heel pad in individuals with and without plantar heel pain while walking. METHODS The sagittal thickness and axial compressive strain of the heel pad were estimated in vivo from dynamic lateral foot radiographs acquired from nine subjects with unilateral plantar heel pain and an equivalent number of matched controls, while walking at their preferred speed. Compressive stress was derived from simultaneously acquired plantar pressure data. Principal viscoelastic parameters of the heel pad, including peak strain, secant modulus and energy dissipation (hysteresis), were estimated from subsequent stress-strain curves. FINDINGS There was no significant difference in loaded and unloaded heel pad thickness, peak stress, peak strain, or secant and tangent modulus in subjects with and without heel pain. However, the fat pad of symptomatic feet had a significantly lower energy dissipation ratio (0.55+/-0.17 vs. 0.69+/-0.08) when compared to asymptomatic feet (P<.05). INTERPRETATION Plantar heel pain is characterised by reduced energy dissipation ratio of the heel pad when measured in vivo and under physiologically relevant strain rates.


American Journal of Sports Medicine | 2010

Plantar Enthesopathy: Thickening of the Enthesis Is Correlated With Energy Dissipation of the Plantar Fat Pad During Walking

Scott C. Wearing; James E. Smeathers; Stephen R. Urry; Patrick M. Sullivan; Bede Yates; Philip Dubois

Background The enthesis of the plantar fascia is thought to play an important role in stress dissipation. However, the potential link between entheseal thickening characteristic of enthesopathy and the stress-dissipating properties of the intervening plantar fat pad have not been investigated. Purpose This study was conducted to identify whether plantar fat pad mechanics explain variance in the thickness of the fascial enthesis in individuals with and without plantar enthesopathy. Study Design Case-control study; Level of evidence, 3. Methods The study population consisted of 9 patients with unilateral plantar enthesopathy and 9 asymptomatic, individually matched controls. The thickness of the enthesis of the symptomatic, asymptomatic, and a matched control limb was acquired using high-resolution ultrasound. The compressive strain of the plantar fat pad during walking was estimated from dynamic lateral radiographs acquired with a multifunction fluoroscopy unit. Peak compressive stress was simultaneously acquired via a pressure platform. Principal viscoelastic parameters were estimated from subsequent stress-strain curves. Results The symptomatic fascial enthesis (6.7 ± 2.0 mm) was significantly thicker than the asymptomatic enthesis (4.2 ± 0.4 mm), which in turn was thicker than the enthesis (3.3 ± 0.4 mm) of control limbs (P < .05). There was no significant difference in the mean thickness, peak stress, peak strain, or secant modulus of the plantar fat pad between limbs. However, the energy dissipated by the fat pad during loading and unloading was significantly lower in the symptomatic limb (0.55 ± 0.17) when compared with asymptomatic (0.69 ± 0.13) and control (0.70 ± 0.09) limbs (P < .05). The sonographic thickness of the enthesis was correlated with the energy dissipation ratio of the plantar fat pad (r = .72, P < .05), but only in the symptomatic limb. Conclusion The energy-dissipating properties of the plantar fat pad are associated with the sonograpic appearance of the enthesis in symptomatic limbs, providing a previously unidentified link between the mechanical behavior of the plantar fat pad and enthesopathy.


British Journal of Sports Medicine | 2013

DEFORMATION OF THE HUMAN HEEL PAD DURING WALKING APPROACHES PREDICTED LIMITS OF PAIN TOLERANCE

Scott C. Wearing; Sue L. Hooper; Philip Dubois; James E. Smeathers

Background The plantar heel pad is a specialised fibroadipose tissue that attenuates and dissipates, in part, the impact energy associated with heel strike. Although near maximal deformation of the heel pad has been shown to occur during running,1 in vivo measurement of the mechanical properties of the heel pad during walking remain largely unexplored. This study used a digital fluoroscope, synchronised with a pressure plate, to obtain force–deformation data for the heel pad during walking. Methods Dynamic lateral foot radiographs were acquired from sixteen healthy adults while walking at their preferred speed. Sagittal thickness and deformation of the heel pad relative to the support surface were calculated. Simultaneous measurement of peak force beneath the heel was used to estimate the principal structural properties of the heel pad. Results Transient loading profiles associated with walking induced rapidly changing deformation rates in the heel pad and resulted in irregular load–deformation curves. The initial stiffness (32±11 N.mm–1) of the heel pad was an order of magnitude lower than its final stiffness (212±125 N.mm–1) and only 1.0 J of energy, on average, was dissipated by the heel pad during walking. Peak deformation (10.3 mm) approached that predicted for the limit of pain tolerance (10.7 mm). Discussion/Conclusions Peak deformation of the heel pad approached that predicted for the limit of pain tolerance,2 suggesting the heel pad operates close to its pain threshold even at speeds encountered during walking. These findings raise questions as to the function of the heel pad during gait, highlight the need for alternative energy dissipating mechanisms during high impact activities often encountered in sport, and provide insight as to why barefoot runners adopt ‘forefoot’ strike patterns that minimise heel loading.


Gait & Posture | 2004

Errors in measuring sagittal arch kinematics of the human foot with digital fluoroscopy.

Scott C. Wearing; James E. Smeathers; Bede Yates; Patrick M. Sullivan; Stephen R. Urry; Philip Dubois


Medicine and Science in Sports and Exercise | 2014

Force-deformation properties of the human heel pad during barefoot walking.

Scott C. Wearing; Sue L. Hooper; Philip Dubois; James E. Smeathers; Albrecht Dietze


Faculty of Health; Institute of Health and Biomedical Innovation | 2014

Force-deformation properties of the human heel pad during barefoot walking

Scott C. Wearing; Sue L. Hooper; Philip Dubois; James E. Smeathers; Albrecht Dietze


Centre for Health Research; Faculty of Health; Institute of Health and Biomedical Innovation | 2004

Sagittal movement of the medial longitudinal arch is unchanged in plantar fasciitis

Scott C. Wearing; James E. Smeathers; Bede Yates; Patrick M. Sullivan; Stephen R. Urry; Philip Dubois


Centre for Health Research; Faculty of Health; Institute of Health and Biomedical Innovation | 2010

Plantar enthesopathy : thickening of the enthesis is correlated with energy dissipation of the plantar fat pad during walking

Scott C. Wearing; James E. Smeathers; Stephen R. Urry; Patrick M. Sullivan; Bede Yates; Philip Dubois

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James E. Smeathers

Queensland University of Technology

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Scott C. Wearing

Queensland University of Technology

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Bede Yates

Queensland University of Technology

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Stephen R. Urry

Queensland University of Technology

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Patrick M. Sullivan

Queensland University of Technology

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Sue L. Hooper

Queensland Academy of Sport

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