Abnormal Gait.ppt
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1、Abnormal Gait,Department of Physical Therapy NEW YORK UNIVERSITY,Historical Perspective,Tendency to classify gait according to disease or injury state Hemiplegic gait Parkinsonian gait Spastic gait Quadra- or paraplegic gait Amputee gait, etc.,Rationale,A specific disease or injury state manifested
2、as a discrete and clinically describable problem with the mechanics of gait,Our Starting Point,Well take a deficit-oriented vs. disease- oriented approach to abnormal gait analysis Example: “How might a spastic hamstring on one side, secondary to hemiplegia caused by a CVA, affect gait mechanics?”,A
3、nswer,A spastic hamstring may limit step or stride excursion and/or pelvic transverse rotation,Preferred Rate of Ambulation,Free or comfortable walking speed Self-selected pace Rate at which the normal individual is most energy efficient Range: 2.5 - 4.0 mph (cadence of 75 - 120 steps per minute) Wi
4、ll vary from individual-to-individual,Walking Rates - Historical Perspective,Historically walking rates classified as: Slow: 75 - 90 steps per minute Medium: 90 - 105 steps per minute Fast: 105 - 120 steps per minute,Energy Cost vs. Rate,Summary & Interpretation,Oxygen expenditure is least while wal
5、king at a rate somewhere between 85 to 110 steps per minute irrespective of stride (or step) lengthIndividuals tend to gravitate toward a self-selected pace which is most energy efficient for that individual,Enter - The Idea of a Preferred Rate,A preferred rate of ambulation is a self-selected walki
6、ng pace that an individual assumes that is most energy efficient,Clinical Implication,Since there is apparently a rate-dependent issue that drives gait efficiency the PT should understand that going slower than and faster than the preferred rate will lead to inefficiency and potential stress on the
7、cardiovascular and motor control systems,Why is Gait More Efficient at Preferred Rate?,What is the relationship between energy efficiency and a preferred rate of ambulation?,The Center of Gravity (COG),COG located at S1 - S2 During preferred rate walking the COG approximates a sinusoidal curve from
8、the: Sagittal perspective - no greater than a 2” peak-to-valley excursion Frontal perspective - no greater than a 2” medial-to-lateral excursion,Path of the COG,Distortion of the Path of the COG,A distorted path of the COG will require mechanical and motor control compensations that will: Disrupt no
9、rmal timing of events Over-ride normal gait control Change from automatic to manual control strategies Lead to over-correction of gait mechanics,The Result,Increased energy expenditure,A Simple Example,Walking with a stiff-knee (“stiff-knee gait”) with a cylinder cast During stance the HAT will vaul
10、t over the fixed foot (especially during mid-stance) COG will be deflected higher than the usual 2” upward vertical displacement with increased energy cost,Who Walks with a Stiff Knee?,Transient knee injury patient (e.g., surgical repair of a ligament Hemiplegic with loss of knee control The AK ampu
11、tee with a locked-knee prosthesis The BK amputee with poor knee controlShould we consider each case the SAME?,The Control of Gait,Motor control options: Manual control theory - thinking about having to take a step each time you want to advance the foot forward Automatic control theory - an automatic
12、 control system that accounts for gait mechanics without having to think about foot placement and other metrical details,Which one is it?,Think about this.,An Everyday Occurrence,Youre walking along 23rd Street, heading west toward your bus stop Youre thinking about what was discussed in Kinesiology
13、 class today Youre also thinking that there is a lot a traffic and its going to take you forever to get home tonight.,Questions,Are you thinking about foot placement? Are you thinking about how long each step should be? Are you thinking about trunk and pelvic rotation in the transverse plane and mai
14、ntaining reciprocal arm-swing? Are you thinking about.,Answer,Probably NOT!Why? Your gait control is on automatic pilotWhen do you have to think about gait control? When theres a perturbation,Central Pattern Generator (CPG),CPG - a group of synaptic connections probably at the spinal cord level whic
15、h are triggered by an event or conditionWhen a threshold is met via a triggering mechanism the CPG appears to be activated and takes over automatic control of gait metrics - i.e., you dont have to think about it,Evidence,Spinalized (cord transected) cats suspended over a treadmill will walk with an
16、alternating, striding quadripedal gaitHuman quadriplegics have also “walked” this way,CPG and Supraspinal Influence,Gait perturbations Example: Someone walks across your path from the side that you didnt see Theres a need to take immediate corrective action to avoid a collision Supraspinal centers a
17、ppear to over-ride the CPG and switch to a manual control strategy,What Triggers a CPG?,There seems to be a close relationship between activating a CPG for gait control and preferred rate of ambulationIn other words, there is a rate-dependent relationship between normal gait mechanics and its contro
18、l mechanism,So.,It appears we maintain the path of the COG within very tight limits and therefore expend the least amount of energy by assuming a preferred rate which in turn leads to an activation of a CPG,Think About This.,Whats one of the most common things heard during gait training in a PT clin
19、ic?,“Mr. Jones, while youre walking, I want to go”,“.very slow!”,What are some possible implications of this?,Mr. Jones will be safe - probably wont fall and break his hip (good news). Mr. Jones wont sue you (good news). The path of the COG may be distorted (bad news). Energy cost may increase (bad
20、news) Suppose Mr. Jones has a cardiac condition?,What are some possible implications of this?,Mr. Jones may never reach his pre-injury/disease preferred rate of ambulation and therefore never trigger a CPG that automates gait (bad news).Mr. Jones gait may never look normal (bad news).,Is it possible
21、 that.,going very slow might actually cause Mr. Jones to lose his balance and fall?Why?,Factors That Lead to the Initiation of Gait,Assume right LE will advance first:Weight shift to left LE (unloads right hip) Left hip moves into (hyper-) extension and precedes right hip flexion Right side of pelvi
22、s rotates medially preceding right hip flexion COG moves over right foot after its advanced,Factors That Lead to the Initiation of Gait,Successful completion of these events probably leads to a triggering of a CPG as preferred rate is attained,Gait Training Scenario,Mrs. Flanagan is standing in the
23、parallel bars with her physical therapist, Dudley Doright, getting ready to take a left step to start walking.We hear the PT say, “Now, Mrs. Flanagan, I want you to put your left foot forward and take a step”,Where is the patients COG relative to her base-of-support? What is probably the size of the
24、 left step (step length) relative to the right? What impact will this likely have on her forward velocity? What are the chances of attaining her pre-injury/disease preferred rate?,Deficit-Oriented Gait Analysis,Questions: Do diseases/injuries specifically manifest as a stereotypical gait pattern? or
25、 Does the disease/injury lead to a deterioration of control parameters which cause gait deficits?,Response,If you believe the latterit shouldnt matter what the patients problem isIf you understand the consequence of the disease or injury (loss of motor control, weakness, damaged supportive structure
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