Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chapter 12 Fundamentals of Human Gait Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. Gait Cycle Describes important events occurring between two successive heel contacts of same limb Gait cycle is described as occurring between 0% and 100% and includes stance phase and swing phase Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 2 Stance Phase Heel contact Foot flat Lower limb contacts ground (0% of gait cycle) Entire plantar aspect is on ground (8% of gait cycle) Mid stance Body’s weight passes directly over supporting lower extremity (30% of gait cycle) Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 3 Stance Phase – cont’d Heel off Toe off Heel comes off ground (40% of gait cycle) Toe leaves ground (60% of gait cycle) Push off Describes combined actions of heel off and toe off, when stance foot is literally “pushing off” toward next step Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 4 Swing Phase Early swing Mid swing Period from toe off to mid swing (65% of gait cycle) Period when foot of swing leg passes next to foot of stance leg (75% of gait cycle) Late swing Period from mid swing until heel contacts ground (85% of gait cycle) Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 5 Additional Terminology of Gait Stride Events that take place between successive heel contacts of same foot Stride length Distance traveled in one stride—two consecutive heel contacts of same foot Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 6 Additional Terminology of Gait – cont’d Step Step length Events occurring between successive heel contacts of opposite feet Distance traveled in one step Step width Distance between heel centers of two consecutive foot contacts Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 7 Additional Terminology of Gait – cont’d Cadence Also called step rate, defined as number of steps Walking velocity Speed at which an individual walks Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 8 Stance Phase: Heel Contact Gait cycle beginning, when heel first contacts ground Center of gravity of body is at its lowest point Ankle is held in neutral dorsiflexion Ankle transitions toward foot-flat stance and dorsiflexor muscles are eccentrically activated to lower ankle into plantar flexion Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 9 Stance Phase: Heel Contact – cont’d Knee is slightly flexed, positioned to absorb shock of initial weight bearing Quadriceps are eccentrically active to allow a slight “give” to flexed knee and help prevent knee from buckling Hip extensors are isometrically active to prevent trunk from jackknifing forward Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 10 Stance Phase: Foot Flat Point in which entire plantar surface of foot contacts ground Loading-response phase of gait Muscles and joints of lower limb assist with shock absorption, as lower extremity continues to accept increasing amounts of body weight Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 11 Stance Phase: Foot Flat – cont’d Ankle has just rapidly moved into 5-10 degrees of plantar flexion Knee continues to flex to about 15 degrees, acting as a shock absorbing “spring” Quadriceps continue to function eccentrically, and hip extensors guide hip toward increasing extension Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 12 Stance Phase: Mid Stance Occurs as leg approaches vertical position Leg is in single-limb support, as other limb is freely swinging forward Dorsiflexor muscles are inactive; plantar flexor muscles are eccentrically active, controlling rate at which lower leg advances over foot Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 13 Stance Phase: Mid Stance – cont’d Knee reaches near-fully extended position Hip abductors play important role in stabilizing pelvis in frontal plane, preventing opposite side of pelvis from dropping excessively Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 14 Stance Phase: Heel Off Occurs just after mid stance as lower leg and ankle begin “pushing off,” continuing to propel body forward Begins as heel breaks contact with ground Plantar flexor muscles and Achilles tendon stretch in preparation for propulsion At heel off, plantar flexor muscles have switched their activation from eccentric to concentric Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 15 Stance Phase: Heel Off – cont’d Extended knee prepares to flex, usually driven by short burst of activity from hamstring muscles Hip continues to extend, ending in about 10 degrees of extension Eccentric activation of hip flexors, particularly iliopsoas, helps control amount of hip extension that occurs Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 16 Stance Phase: Toe Off Final event of stance phase of gait Toe off ends when toes break contact with ground Toes are in marked hyperextension at metatarsophalangeal joints, supported by activation of intrinsic foot muscles Ankle continues plantar flexing through concentric activation of plantar flexor muscles Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 17 Stance Phase: Toe Off – cont’d At toe off, knee is flexed 30 degrees, but hamstrings are only minimally active Most knee flexion arises as a result of inertia produced, as hip is pulled into flexion In final stage of toe off, hip is in nearly-neutral position, with thigh nearly perpendicular to ground Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 18 Swing Phase: Early Swing Leg begins to accelerate forward Plantarflexed ankle begins to dorsiflex, clearing ground as it is advanced forward Knee continues to flex, and hip flexors continue to contract, pulling extended thigh forward Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 19 Swing Phase: Mid Swing Midpoint of swing phase Contralateral leg is mid stance, supporting body weight Ankle is held in neutral position Knee is flexed about 50-60 degrees, helping advance lower limb Hip approaches 35 degrees of flexion, continuing to be pulled forward through concentric hip flexor activation Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 20 Swing Phase: Terminal Swing Limb begins to decelerate in preparation for heel contact Leg is placed well in front of body, preparing for transition to accept body weight Ankle dorsiflexors are activated isometrically, positioning foot for heel contact Knee has moved from flexed position of mid swing to almost full extension Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 21 Swing Phase: Terminal Swing – cont’d Hamstrings are active eccentrically at this time to slow rapidly extending knee Hip flexor muscles become inactive in terminal swing Hip extensors decelerate forward leg progression leg through eccentric activation Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 22 Muscle and Joint Interactions in Frontal Plane Abductor muscles play important role in frontal plane hip stability Without activation of hip abductors on stance leg, opposite side of pelvis would drop under force of gravity, known as positive Trendelenburg sign Activation of stance leg’s hip abductors holds pelvis level Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 23 Muscle and Joint Interactions in Frontal Plane – cont’d Strong medial and lateral collateral ligaments of knee provide natural stability to knee in frontal plane Loss of this stability may lead to issues such as genu valgus, potentially altering normal gait mechanics Instability of knee may arise from impairments at hip or foot Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 24 Muscle and Joint Interactions in Frontal Plane – cont’d While walking, subtalar and transverse tarsal joints cooperate to transform foot from pliable platform at early stance to more rigid platform at late stance Position of supination arranges bones of foot to their most stable position, forming rigid lever for push-off Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 25 Muscle and Joint Interactions in Horizontal Plane Much of lower limb control within horizontal plane during walking occurs at hip and foot During walking, pelvis rotates in horizontal plane about a vertical axis of rotation through hip joint of stance leg Because trunk remains relatively stationary during walking, lumbar spine must rotate slightly to decouple rotating pelvis from thorax Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 26 Foot Slap On heel strike, foot quickly drops into plantar flexion, producing a slapping sound as forefoot impacts ground Impairment Weakness of dorsiflexors May follow injury to common peroneal nerve or hemiplegia Reason for deviation Inadequate strength in dorsiflexor muscles to slowly control plantar flexion following heel contact Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 27 High Stepping Gait Individual appears to be stepping over an imaginary obstacle; initial foot contact is typically made with forefoot or entire plantar surface of foot Impairment Marked weakness of dorsiflexors—resulting in “foot drop” Possibly following injury to common peroneal nerve or hemiplegia Reason for deviation In order to clear foot from ground, hip and knee must be excessively flexed to advance leg Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 28 Hip Circumduction Swing leg is advanced in semi-circle arc Impairment Inability to “shorten” swing leg, possibly due to reduced active or passive hip or knee flexion or as a result of wearing a “straight-leg” brace at knee Reason for deviation Circumduction creates extra clearance to advance functionally “long leg” Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 29 Hip Hiking Excessive elevation of pelvis on “swing” side Impairment Inability to functionally “shorten” swing-leg Possibly due to weak hip flexor muscles Reason for deviation Elevating or “hiking” pelvis provides extra clearance for advancing leg Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 30 Weak Gluteus Maximus Gait Backward lean of trunk during foot-flat phase Impairment Weakness of hip extensors—gluteus maximus Reason for deviation Leaning backward during stance phase shifts body’s line of gravity posterior to hip, reducing need for active hip extension torque Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 31 Walking with Hip and/or Knee Flexion Contracture Flexed position of hip and knee during stance phase of gait, often referred to as a “crouched gait” Impairment Hip or knee flexion contracture Reason for deviation Increased tightness in tissues that allow hip and knee extension Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 32 Weak Hip Abductor Gait During single-limb support, pelvis and trunk lean excessively to same (uncompensated) or opposite (compensated) side as weak hip abductor muscles Impairment Weakness of hip abductor muscles Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 33 Weak Hip Abductor Gait – cont’d Reason for deviation “Uncompensated” response: hip abductors of stance leg are unable to produce enough force to hold pelvis level “Compensated” response: purposely leaning trunk and pelvis to same side as weak muscles shifts line of gravity closer to stance hip Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 34 Vaulting Individual rises up on toes of stance foot while swinging contralateral leg forward Impairment Any impairment of lower extremity that reduces ability to functionally reduce length of limb Reason for deviation Standing on tiptoes creates extra clearance for contralateral leg to clear ground during swing Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 35 Weak Quadriceps Gait Knee remains fully extended throughout stance, combined with excessive forward lean of trunk Impairment Weakness or avoidance of activation of quadriceps muscle Reason for deviation Forward lean of trunk shifts line of gravity anterior to mediallateral axis of knee Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 36 Genu Recurvatum Excessive hyperextension of knee during stance phase of gait Impairment A: Quadriceps and/or knee flexor paralysis B: Plantar flexion contracture Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 37 Genu Recurvatum: Reasons for Deviation A: Overstretched posterior capsule of knee and/or paralysis of muscles that cross posterior side of knee (hamstrings) fail to limit knee extension B: Leg deviates posteriorly relative to ankle and forces knee into hyperextension, eventually overstretching posterior capsule Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 38 Summary Gait training is vital component of physical therapy Individual’s level of independence and length of stay is often determined by ability to safely ambulate from one place to another Copyright © 2014, 2009 by Mosby, an imprint of Elsevier Inc. 39