Gait Flashcards
1
Q
Define a step
A
- Initial contact to contralateral initial contact
- Normal step length = 72 cm or ~28.4 in
2
Q
Define stride
A
- Initial contact to subsequent ipsilateral initial contact
- Normal stride length = 144 cm or ~56.7 in
3
Q
Define step width
A
- The lateral distance b/w the heel centers of two consecutive foot contacts
- Normal step width = 7-9 cm or ~2.8-3.5 in
4
Q
Define foot angle
A
- The degree of “toe out” or the line of progression b/w the body & the long axis of the foot
- Normal foot angle = 10-14 degrees
5
Q
Define cadence
A
- The number of steps taken per minute (step rate)
- Average adult cadence = 110 steps/min
6
Q
Define stride time
A
- The time for a full gait cycle to complete
- Average adult stride time = 1 sec
7
Q
Define step time
A
- The time for a right or left step to complete
- Average adult step time = 0.5 sec
8
Q
Define stance time
A
- Time reference foot is on the ground
9
Q
Define swing time
A
- Time reference foot is off the ground
10
Q
Define double limb support time
A
- Time both feet are on the ground that occurs twice during the gait cycle
11
Q
Define single limb support time
A
- Time non reference foot is swinging forward & reference foot is on the ground
12
Q
What is normal gait speed
A
- 1.37 m/s
13
Q
Ways to calculate gait
A
- Measuring the time it takes to cover a given distance
- Measuring the distance covered in a given amount of time
- Multiplying the step rate by the step length
14
Q
What phases of gait are a part of weight acceptance
A
- Initial contact
- Loading response
15
Q
What phases of gait are a part of single limb support
A
- Mid-stance
- Terminal stance
16
Q
What phases of gait are a part of swing limb advancement
A
- Pre-swing
- Initial swing
- Mid-swing
- Terminal swing
17
Q
What are the 4 basic functions of normal gait
A
- Weight bearing stability: think ground reaction forces at different phases of gait & what effect these have on the hip & knee & ankle joint
- Stance limb progression: heel rocker maintains fwd progression from heel strike to foot flat; forefoot rocker does fwd progression to metatarsal heads with heel rise
- Shock absorption: ankle plantar flexion followed by knee flexion
- Energy conservation
18
Q
Difference b/w a hard and soft prosthetic heel during tibial advancement/heel strike
A
- Too hard of a heel will cause the limb to progress forward too fast and result in knee buckling
- Too soft of a heel will squish and lead to the foot going flat to the ground too early results in a knee extension force/thrust
19
Q
Describe weight bearing stability in gait
A
- Muscles around the hip, knee, & ankle sequentially stabilize these joints as the body weight is transferred to the stance limb
- Pattern of muscle activation is dictated by the alignment of the body weight line to the joint
- As the vector moves away from the joint center, a rotational force or moment develops that must be controlled by the opposing muscles to preserve postural stability
20
Q
What are the 3 demands of weight acceptance
A
- Shock absorption
- Initial limb stability
- Preservation of progression
21
Q
What is the most challenging task in the gait cycle
A
- Weight acceptance
22
Q
What are the 2 demands of single limb support
A
- One limb has total responsibility for supporting body weight in both the sagittal & coronal planes
- Progression continues
23
Q
What are the 3 demands of swing limb advancement
A
- Lifting of foot
- Completion of stride length
- Preparation for next stance interval
24
Q
Describe the cost of walking
A
- O2 Cost = Rate of O2 Consumption ÷ Gait Speed
- Minimized at preferred walking speeds
- Higher cost with slow or fast walking
25
What are the weight bearing regions (pressure tolerant) for transtibial prosthesis
- Anterior: Patella tendon and Pretibial musculature
- Posterior: Gastric-soleus muscle belly and Popliteal fossa
- Medial: Medial tibial flare
- Lateral: Shaft of fibula
26
Difference b/w terminal stance and pre-swing
- In pre-swing the limb is unloaded
- In terminal stance the limb is still under load
27
What is the concern for putting pressure of the fibula shaft
- Compression of the fibular nerve
28
What happens to pressure areas that are over muscle bellies overtime
- Atrophy which will lead to socket adjustments later on which is normal
29
What is a good landmark to make sure that the socket fits properly
- The patella tendon bar area
30
Pressure on tibia through the gait cycle
- Loading response: anterior distal/posterior proximal
- Mid-stance: all pressure tolerant weight bearing surfaces
- Terminal stance: anterior proximal/posterior distal
- Pre-swing: anterior distal/posterior proximal
- Initial swing: anterior proximal/posterior distal
- Mid-swing: foot clearance dependent on appropriate suspension & pelvic control on contralateral side
- Terminal swing: anterior distal/posterior proximal
31
A lot of impairments in swing phases are due to inadequate terminal stance True/False
- True
32
Define suspension
- The interface between the prosthetic and the residual limb
33
What is inadequate suspension
- When off loaded the prosthetic is being pulled by gravity causing the leg to be long leads to a compensatory hip hike
34
During mid-stance what force couples are occurring
- Medial proximal/lateral distal
35
Describe unleveled bones
- Jagged bones from surgery
- Appear more prominent as atrophy occurs
- May lead to skin breakdown during weight bearing
36
What do you due before putting on the prosthesis
- Evaluate weight bearing regions
37
What are the goals of prosthetic training
- #1: don't compromise your PT session with poor fitting limbs that cause you more problems
#2: solve issues within your scope without the prosthetist
38
Describe the initial check of the prosthesis
- Check height (pub-floor)
- Foot is level in the shoe
- 5-7 degrees socket flexion (means knee flexion or moved anteriorly)
- Weight line is near posterior third of foot
- Pin suspension engages/disengages easily
39
What happens if too much flexion or weight line too far forward?
- Rapid knee flexion
- Increased distal tibia pressure
40
Before calling the prosthetist ask what
- Take the leg off & put on again
- When in gait does it hurt?: on heel, mid foot, or toe
- Can you duplicate the pain with the leg off?
- Are there pressure areas on the limb you can relate to gait?
41
Describe residual limb pain
- Pain in the limb between the end of the residual limb & the next most proximal joint
42
Describe MSK pain for amputees
- Amputation has been associated with increased prevalence of secondary MSK pain in the lumbar spine & in the contralateral knee/hip
43
Describe phantom limb pain
- Pain distal to the end of the residual limb
- Onset in early post amputation period
- Often nocturnal
- Gradually reduced in intensity & frequency over time
- Can be exacerbated by residual limb pain
44
Describe phantom limb sensation
- Non-painful sensations distal to the residual limb
- Wide spectrum of sensory experiences that vary in intensity, frequency, & severity
45
Describe residual limb management through the different stages
- Preoperative: desensitization exercises, skin hygiene, & description of types of pain; explain & differentiate b/w residual limb pain, phantom pain, & phantom sensation
- Postoperative: Donning/doffing of ACE wrap or shrinker if appropriate; desensitization exercises, skin hygiene, & description of types of pain
- Pre-prosthetic: care of residual limb
- Prosthetic training: donning/doffing of prosthetic system, use of shrinker when out of the prosthesis, skin checks & skin hygiene, management of sock ply if appropriate, observe pressure points & protect contralateral foot
- Long term follow up: foot care & skin checks
46
Slide 75
47
Describe cardiovascular endurance in amputees with prosthetics
- Energy cost of walking is greater in amputees
- Higher level amputations are associated with higher energy costs of gait
- Dysvascular amputations demonstrate greater energy cost of gait than those with traumatic amputations
- Self-selected gait speed decreases with higher levels of amputation
- Generally more efficient for an individual with a prosthesis to ambulate with the prosthesis than it is to ambulate w/o the prosthesis using an AD
48
Difference in energy expenditure for over ground walking between transtibial and transfemoral amputees
- Energy expenditure for over-ground walking in people with unilateral dysvascular amputations is increased by up to 36% for transtibial and up to 65% for transfemoral amputations
49
Describe the socket-residual limb interface
- The static and dynamic pressure distribution of the residual limb within the socket are essential considerations in patient comfort, function, and well-being
- You could have the best prosthetic foot on the market, but if your socket is uncomfortable you’re not going to walk very far
50
Describe a joint and corset
- May/may not have a waist belt depending on how prominent the femoral condyles are
- May include posterior check strap to limit full knee extension
- Load-bearing forces were split b/w the socket & a thigh corset
- Primarily indicated for very short residual limb (transtibial)
51
Describe a patella tendon bearing (PTB) socket
- Localization of load-bearing pressures soon designated "pressure tolerant" regions, & targeted offloading of regions generally intolerant to pressure
- Patellar tendon bar & medial tibial flare are major WBing areas for a PTB socket
- Total contact socket design has been used for ≥60 years for a comfortable prosthetic fit
52
Describe a total surface bearing (TSB) socket
- Globally reduced socks volumes & relatively equal load bearing pressures throughout the entirety of the socket
- Allows increased surface area for WBing
- Shear forces run parallel to the limb surface & are best mitigated through the use of a socket interface
- Normal forces are those that are applied perpendicular to the surface of the limb
53
Viscoelastic interface liners provide reduction of shear at skin surface, these are fabricated from a range of elastic materials including:
- Silicone
- Urethane
- Other Gel-like substances
54
What is included in the socket interface
- Elastic liners
- Socks
- Foam liners
55
Describe elastic liners
- Composed of silicone, urethane, & other thermoset elastomeric materials
- Used with & w/o external fabric covers & imbedded matrices of reinforcing mesh material
- Fabricated in custom & non-custom variants
56
Describe socks
- Compressible textiles, occasionally infused w/thermoplastic elastomer gels
- Primarily used to accommodate changes in limb volume but occasionally used as a primary interface b/w the limb & socket
57
Describe foam liners
- Nonporous material of soft to moderate durometer, frequently heat contoured over a positive model of the limb to mimic the contours of the socket
- Good option for individuals with fluctuating residual limb volume
58
Compared with traditional PTB-designed interfaces, the use of gel liners reportedly:
- Decreases walk aid dependence
- Improves prosthetic suspension when used with a shuttle lock mechanisms compared with supracondylar, cuff, or corset alternatives
- Improves load distribution
- Decreases pain & increases comfort
59
Describe an anatomic suspension
- Proximal socket contours are shaped to secure purchase over the bony shape of the femoral condyles
60
Describe a mechanical "locking" liner suspension
- Combo of an elastic liner fitted with a distal locking pin which engages a locking mechanism fabricated into the socket
- Suspension results from the suction of the liner & transfers through the locking mechanism attached to the socket
- Reinforcing mesh is frequently impregnated into the liners distally to limit longitudinal dissension of the liner
61
Describe suction suspension
- Creation of an airtight socket environment
- Frequently obtained through the use of a proximal sealing sleeve worn against the thigh & outer surface of the socket but alternatively obtained with sealing gaskets worn over the external surface of the interface liner
- During gait when the prosthesis would separate from the limb it results in an increase negative pressure further resulting in an increasing force keeping the prosthesis on the limb
62
Describe a vacuum assisted suction suspension
- Similar to suction suspension with the addition of a vacuum element that actively draws air form the socket environment resulting in elevated negative pressure w/o need for initial prosthesis distraction from the residual limb to obtain negative pressure
63
Compared with Total Surface Bearing-designed interfaces with pin locking suspension mechanism, VAS interfaces reportedly:
- Reduce time to prosthetic fitting and improve mobility post-operative or post-ulceration
- Decrease step activity
- Decrease pistoning
- Decrease positive pressure in stance phase of gait
- Increase negative pressure in swing phase when walking
- Could decrease daily limb volume changes, maintain a better socket fit
- Improve mobility, comfort, stability, proprioception, functional outcome, overall satisfaction, prosthetic function, and quality of life.
- Reduce skin irritation, cure residual limb wounds faster, and decrease pain.
- More maintenance was required for VAS systems
64
Indications for a vacuum assisted suspension (VAS)
- Indicated to decrease daily limb volume changes while facilitating more favorable pressure distribution during gait-
65
Precautions for VAS
- VAS requires both awareness & compliance on the part of the end user & are not universally indicated
- Possibility of creating skin blisters when worn improperly
- Requires that the pt has sufficient cognitive ability to know what to watch for & how to fix problems
- Requires more maintenance than other suspension systems
66
Which type of suspension is best among modern suspension optiosn
- Vacuum-assisted suspension (VAS) sockets permit the least amount of pistoning within the socket
- Suction suspension
- Pin lock suspension
- Traditional suspension options of supracondylar, cuff, and sleeve suspension provide comparatively compromised suspension
67
Why do we care about sockets & suspension
- Socket has been the most important consideration in lower limb prosthesis user satisfaction
- Dissatisfactionn is mainly caused by strains & injuries associated with socket fit
- Pressure distribution (within the socket) directly/indirectly affects the effective indices of user satisfaction
68
Describe heel position and its effects on socket & foot alignment
- Heel too low creates excessive extensor moment at the knee in mid-stance, hampering forward progression
- Heel too high creates a flexion moment at the knees in mid-stance leading to early "drop off" & compromise of stance phase stability
- Goal is pylon vertical*
69
Socket and foot alignment during gait
- Initial contact: made at the heel, & compression of the prosthetic heel simulates controlled lowering of the foot during loading response
- Mid-stance: WBing forces move anteriorly to the ball of the foot
- Terminal stance: the anterior portion of the prosthetic foot simulates toe extension & the heel rises
- Pre-swing: the individual rolls over the toe & moves into knee flexion for effective shortening of the limb for swing limb clearance
70
Describe the K-levels that are based on the amputee mobility predictor
- Level 0: Does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance their quality of life or mobility.
- Level 1: Has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence.
- Level 2: Has the ability or potential for ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs or uneven surfaces.
- Level 3: Has the ability or potential for ambulation with variable cadence.
- Level 4: Has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels.
71
Describe the amputee mobility predictor
- Ceiling effect with higher level mobility
- Scores >37 indicate that the pt demos proficient balance, postural stability during sitting & standing, and the ability to vary walking cadence then they are ready to perform activities beyond basic ambulation
- Scores 32-47: have adequate balance with both static & lower level dynamic activities, demo better than average lower limb power, & show competent use of prosthesis
72
Potential functional ability is based on the reasonable expectations of the prosthetist, and treating physician, considering factors including, but not limited to the following:
- Pt's past Hx
- Pt's current condition including the status of the residual limb & the nature of other medical problems
- Pt's desire to ambulate
73
Slide 112
74
Recommendations or single axis foot
- Pts ambulating at a single speed who require greater stability during weight acceptance bc of weak knee extensors or poor balance
75
Biomechanics of a single axis foot
- Prosthetic comes into full contact with the floor more quickly during weight acceptance which decreases magnitude of the external knee flexion moment
- This reduces the likelihood of a knee-buckling event, creating a more stable environment for users with weak knee extensors or transfemoral prostheses
76
Recommendation for energy storage & return foot (ESAR)
- Pts at elevated risks for overuse injury to the contralateral lower limb & lower back
- Pts capable of variable speed and/or community ambulation
77
Biomechanics of a ESAR
- Reductions in the peak ground reaction force experienced by the sound-side limb during weight acceptance which Improved tibial progression into terminal stance
- Shock-absorbing characteristics seem to be more apparent at speeds exceeding self-selected walking velocities
- Reduced energy costs of ambulation are more pronounced at elevated walking speeds, during the negotiation of inclines/declines, and during stair ascent
78
K1 level feet
- Single axis feet are appropriate
- Solid ankle cushioned heel (SACH) foot may not be appropriate for heavier pts
79
K2 level feet
- Lightweight, flexible heel, multi-axial ankle
- Modest energy return
- Flexible bumper cushions dampen PF from heel strike to foot flat (stiffness/softness can be changed)
80
K3 level feet
- Integrated pylon is the lightest design
- ESAR
- Typically carbon fiber or fiberglass
- Reduce energy consumption
- Offer increased ankle ROM
- Reduce sound side loading
- Variable degree of frontal plane motion (inversion/eversion)
- Microprocessor feet: heavier than most ft, require nightly charging, currently limited to single axis, not appropriate for very high activity or running, responses to changes in incline/decline, walking speed, and shoes
81
Line of gravity through the body in standing
- anterior to ankle
- anterior to knee
- posterior to hip
- anterior to 2nd sacral vertebra
- straight through the ear hole
82
Describe loading response 0-12% & muscles activated
- weight is rapidly transferred onto the outstretched limb
- hip stability, controlled knee flexion, & ankle PF
- Hip 20º flexion
- Knee 15º flexion
- Ankle 5-10º PF
- hip extensors & abductors, quads, pretibial muscles/DF
83
Describe midstance 12-30% & muscles activated
- body progresses over single limb
- controlled tibial advancement
- Hip 0º
- Knee 5º flexion
- Ankle 5º DF
- hip abductors, quads initially, gastroc/soleus
84
Describe terminal stance 30-50% & muscles activated
- body moves ahead of the stance limb
- controlled ankle DF with heel rise & trailing limb posture
- Hip 20º ext
- Knee 0-5º flexion
- Ankle 10º DF
- gastroc/soleus
85
Describe pre-swing 50-62% & muscles activated
- rapid unloading of trailing limb as weight is transferred to opposite foot
- passive knee flexion to 40º & rapid ankle PF
- Hip 10º ext
- Knee 40º flexion
- Ankle 15º PF
- hip adductors
86
Describe initial swing 62-75% & muscles activated
- thigh begins advancement as the foot comes up off the floor
- hip flexion 15º & knee flexion 60º
- Hip 15º flexion
- Knee 60º flexion
- Ankle 5º PF
- hip flexors, hamstrings, pretibial muscles/DF
87
Describe mid swing 75-87% & muscles activated
- continued thigh advancement with foot clearance & begin knee extension
- hip flexion 25º, ankle DF 0º
- Hip 25º flexion
- Knee 25º flexion
- Ankle 0º
- hip flexors initially then hamstrings, pretibial muscles/DF
88
Describe terminal swing 87-100% & muscles activated
- final knee extension in preparation for contact with ground
- knee extension to neutral
- Hip 20º flexion
- Knee 5º flexion
- Ankle 0º
- hamstrings & add/abductors, quads, pretibial muscles/DF
