Presentation on theme: "Ambulation and Ambulation Aids"— Presentation transcript:
1Ambulation and Ambulation Aids chapter 12Ambulation and Ambulation Aids
2Gait= A series of rhythmical, alternating movements of the limbs and trunk that causes a forward progression of the center of gravity (CoG).Involves a repetitive loss and recovery of balance through displacing and controlling the motion of the CoG in the most efficient manner
3Gait Cycle= The series of events that occur between the heel strike of one limb and the next heel strike of the same limb.
5Gait ComponentsStep length: the distance covered between heel strike (HS) of one limb and HS of the other limbStride length: The distance covered between the successive HS of one limb and HS of the same limb(continued)
6Gait Components (continued) Cadence: The speed of gait. It can be measured in the number of steps for a period of time (usually steps/min).Cadence and time for gait cycle are related: The longer the period of time for the gait cycle, the slower the cadence.As cadence increases, the time of double support decreases.
9Gait Cycle Phases Stance phase: Swing phase: Double support: 62% of the gait cycleFrom HS of one limb to toe-off (TO) of same limbSome or all of the body’s weight borne on the limbSwing phase:38% of the gait cycleTime the limb is non-weight bearingFrom TO to HSDouble support:20% of the gait cycleBoth limbs in contact with the groundOne limb in late stance, other in early stance
10Stance Phases Heel strike (HS): When the heel strikes the groundSometimes called foot strikeFoot flat (FF): When entire sole of foot contacts groundMidstance (MS): When body is directly over the limb(continued)
11Stance Phases (continued) Heel-off (HO): When heel leaves the ground but ball of foot remains in contactToe-off (TO):When toe leaves the groundFinal phase of gait
12Swing Phases Early swing (ES): Immediately following TO Limb CoG begins accelerating forward to move in front of the body’s CoGSometimes called acceleration phase(continued)
13Swing Phases (continued) Midswing (MSw):Limb passes directly beneath the body.Tibia is perpendicular to the ground.Late swing (LS):Limb passes in front of the body in preparation for HS.Sometimes called deceleration phase.
14CoG and Gait Purpose of gait is to move the CoG. CoG is located approximately anterior to S2.During gait, CoG moves from side to side and from superior to inferior.(continued)
15CoG and Gait (continued) Vertical displacement:CoG is displaced to vertical peak twice in gait cycle.Highest point occurs at MS.Lowest point occurs at double support.CoG follows sinusoidal path in the vertical direction.Total vertical displacement is ~2 in. (~5 cm).Horizontal displacement:CoG is moved from side to side once in gait cycle.CoG follows sinusoidal path in the horizontal direction.Total side-to-side displacement: ~1.75 in. (~4.5 cm).
16Determinants of Gait Six determinants Pelvic rotationPelvic tiltKnee flexion at early midstanceFoot and ankleAnkle and kneeLateral pelvic motionWork together to increase gait efficiency
18Determinants of Gait: Pelvic Rotation Pelvic rotation: ~4° to each sidePelvis rotates left to right and vertically.Left-to-right rotation depends on swing limb (e.g., right limb leads pelvis rotates to left)Amount of swing varies with cadence and step length.(continued)
19Determinants of Gait: Pelvic Rotation (continued) Effect of some rotation occurs at both hips Amplitude of sinusoidal wave crest Severity of deflections between wave arcs Severity of impact with the ground Force needed to change direction of CoG from trough to crest waveSmoothes out deflection points
21Determinants of Gait: Pelvic Tilt Pelvic tilt: ~5°to either sidePelvis drops inferiorly opposite to weight-bearing (WB) limb.Some motion occurs at both hips.Adduction on WB sideAbduction on non-weight-bearing (NWB) sideEffects: Amplitude of sinusoidal waveHow does this effectiveness of hip abductor mechanism?
22Determinants of Gait: Knee Flexion in Early Midstance Knee begins to flex immediately after HS and continues to flex (~15°) until FF.Effects: Amplitude of sinusoidal wave crest Severity of deflections between sinusoidal wave arcs
25Determinants of Gait: Foot and Ankle Talocrural jointCoG is falling and WB limb shortens to dampen impact: Talocrural joint dorsiflexes.Plantar flexes immediately following HS to FF.Dorsiflexes in MS.Begins to plantar flex immediately after MS.(continued)
26Determinants of Gait: Foot and Ankle (continued) Pronated by FF.Begins to supinate immediately after FF.Talocrural center of rotation (CoR) position changes: high at HS, low at MS, high at TO.
27Determinants of Gait: Ankle and Knee At HS:Knee flexes.Ankle CoR moves high to low.At FFKnee begins extension.Ankle CoR remains low.At HOKnee begins flexing to shorten the limb for swing.Ankle CoR rises, then knee flexion increases as ankle CoR continues to rise.(continued)
28Determinants of Gait: Ankle and Knee (continued) Effects: Severity of the deflections between wave arcsSmoothes out the reversal of motion of the CoG at the low point of its courseCombinations of knee and ankle motions gradual change in functional limb length throughout gait
29Determinants of Gait: Lateral Pelvic Motion Lateral displacement of CoG toward stance limb could be as much as 6 in.Effect: produces lateral movement of CoGHip-knee angle lateral movement to 1 in. each side