Post on 13-Jan-2016
description
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Mechanics and control of the pes planus versus normal foot
during jumping and landing
Reporter: Reportor : Zong-Shein Chen
Supervisor : Sai-Wei Yang
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Introduction
Pes planus (flat foot)
- the medial longitudinal arch of foot is lower than established normal parameters
~ Forrester D et al. Imaging of the foot and ankle;1988
- Occurs in approximately 15% of the population
~ Harris R and Beath T. J Bone Joint Surg;1948
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The terms of pes planus :
- Flexible : An observable medial arch during nonweightbearing and a flattening of the arch during weightbearing
- Rigid : A stiff, flattened arch on and off weightbearing
~ Lee MS et al. J Foot Ankle Surg; 2005
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The stages of pes planus : - In clinically and functionally, the rearfoot of flat fo
ot subjects is valgus and the forefoot is varus~ Bertani A et al. Clin Biomech. 1999
~ Magee DJ. Orthopedic Physical
Assessment; 2002
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Abnormal biomechanical behaviors
The MLA collapses right down Most of the plantar surface of foot contact with th
e ground More strain on the plantar aponeurosis Facilitating dorsiflexion Unlocking of the midtarsal joint
~ Prost WJ. Fam Physician; 1979
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Greater inversion ankle moment Greater peak plantarflexion ankle moment Less forefoot adduction Less forefoot total transverse plane ROM
~ Hunt AE et al. Clin Biomech; 2004
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Greater foot pressure under the second and third metatarsal heads
Greater foot pressure under the subhallucal area
~ Hunt GC. Examination of lower-extremity dysfunction; 1990
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Injuries relate to pes planus
Pes planus are associated with a higher risk of injury among physically active people
~ Kulthanan T et al. J Med Assoc Thai; 2004
Subjects with pes planus feet exhibited greater incidences of soft tissue and medial foot injuries and knee injuries
~ Williams DS et al. Clin Biomech; 2001
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Sesamoiditis Plantar fasciitis Achilles tendinitis Medial shin pain Patello-femoral joint pain Metatarsal stress fractures Navicular and fibular stress fractures
~ Hunt AE et al. Clin Biomech; 2004
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Posterior tibialis tendon dysfunction
- Painful pes planus can often be associated with Posterior Tibial Tendon Dysfucntion (PTTD) - The posterior tibial muscle has a significant role in supporting the medial longitudinal arch
~ Kulig K et al. Med Sci Sports Exerc; 2005
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Risk sports for foot and ankle injury
~ DeLee et al. Br J Sports Med; 2003
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Jumping and landing Jump-landing protocols have been used to meas
ure postural sway In an attempt to reduce the landing force the bod
y must anticipate the landing and prepare for it by increasing muscle stiffness
~ McKinely P, Pedotti A. Exp Brain Res ;1992
Further reduction of landing force can be accomplished by allowing the knee and hip to flex more which increases the time of landing providing an attenuation in kinetic energy
~ McNair P et al. Br J Sports Med; 2000
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Effect of Foot Orthotics on Quadriceps and Gluteus Medius Electromyographic Activity During Selected Exercises
Design: Experimental, controlled
Participants: Thirty healthy young adults, 10 with each foot type- Foot type was subjectively categorized by a clinician experienced in lower extremity biomechanic evaluation
~ Hertel J, Sloss BR et al. Arch Phys Med Rehabil. 2005;86:26-30
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Interventions- 3 foot-type groups : pes planus, pes cavus, pes rectus- Each tested in 4 orthotic conditions : no orthotic, 7° medial rearfoot post, 4° lateral rearfoot post, and neutral rearfoot post- Performing 3 different exercises : single-leg squatting, lateral stepdown, and maximum vertical jump
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Outcome Measure : Surface EMG activity for the vastus medialis, vastus lateralis, and gluteus medius during exercises
Results : Less vastus lateralis activity was found with the vertical jump with all orthotic conditions, regardless of foot type
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Purpose
Few investigations focus on the jumping and landing biomechanical behaviors of pes planus subjects
The purpose in this study is to explore the jumping and landing biomechanical behaviors of pes planus subjects
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Hypothesis
The jumping and landing biomechanical behaviors are different between pes planus and normal foot subjects, including COP excursion way, magnitude and direction of GRF, relative motion of foot-leg-knee and the EMG activity of the muscle
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Methods - Participants
Thirty adult, aged from 18 to 25 years old Inclusion criteria :
- arch index > 0. 26
- flexible pes planus~Williams DS et al. 2000
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Exclusion criteria :
- Acute foot injuries
- Previous osseous foot surgery
- Diagnosed with inflammatory arthritis, diabetes mellitus, congenital defects or neuromuscular disease
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Instrumentation
Vision motion analysis system ~ VICON : to collect kinematic data
AMTI force plate : to collect kinetic data
Surface EMG : to collect muscle activation data, tibialis posterior, peroneus brevis and longus, medial and lateral gastrocnemius, vastus medialis and lateralis, biceps femoris
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Procedures
While jumping, subjects were instructed to hold their hands at their waist to restrict arm movement substitution for jump effort
Four conditions, and 3 trials for each condition :1. Vertical jump with both legs at maximum effort and to land with both legs2. Vertical jump with both legs at maximum effort and to land on the dominant leg3. Forward jump with both legs and to land with both legs4. Forward jump with both legs and to land on the dominant leg
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Data analysis
Descriptive statistics and two-way ANOVA tests will be used to compare the difference of testing order effects and four experimental conditions
Tukey’s post-hoc test will be used when an overall significant differences are found
An alpha level of 0.05 will be used to test for significance
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Thanks for your attention
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Reference
Lee MS, Vanore JV et al. Diagnosis and Treatment of Pediatric Flatfoot. J Foot Ankle Surg. 2005;43:341-373
Hunt AE, Smith RM. Mechanics and control of the flat versus normal foot during the stance phase of walking. Clin Biomech. 2004;19:391-397
Ledoux WR, Hillstrom HJ. The distributed plantar vertical force of neutrally aligned and pes planus feet. Gait posture. 2002;15:1-9
Prost WJ. Biomechanics of the foot. Fam Physician. 1979;25:821-31 Hunt GC. Orthopaedic and sports physical therapy. Examination of lower-ex
tremity dysfunction. Second Edition. 1990:395-421 Williams DS, McClay IS et al. Arch structure and injury patterns in runners.
Clin Biomech. 2001;16:341-347 Kulig K, Burnfield JM et al. Effect of foot orthoses on tibialis posterior activat
ion on persons with pes planus. Med Sci Sports Exerc;2005:24-29 Hertel J, Sloss BR et al. Effect of Foot Orthotics on Quadriceps and Gluteus
Medius Electromyographic Activity During Selected Exercises. Arch Phys Med Rehabil. 2005;86:26-30