Presentation on theme: "Department of Physical Therapy NEW YORK UNIVERSITY"— Presentation transcript:
1 Department of Physical Therapy NEW YORK UNIVERSITY Abnormal GaitDepartment of Physical TherapyNEW YORK UNIVERSITY
2 Historical Perspective Tendency to classify gait according to disease or injury stateHemiplegic gaitParkinsonian gaitSpastic gaitQuadra- or paraplegic gaitAmputee gait, etc.
3 RationaleA specific disease or injury state manifested as a discrete and clinically describable problem with the mechanics of gait
4 Our Starting PointWe’ll take a deficit-oriented vs. disease- oriented approach to abnormal gait analysisExample: “How might a spastic hamstring on one side, secondary to hemiplegia caused by a CVA, affect gait mechanics?”
5 AnswerA spastic hamstring may limit step or stride excursion and/or pelvic transverse rotation
6 Preferred Rate of Ambulation Free or comfortable walking speedSelf-selected paceRate at which the normal individual is most energy efficientRange: ~ mph (cadence of ~ steps per minute)Will vary from individual-to-individual
7 Walking Rates - Historical Perspective Historically walking rates classified as:Slow: ~ steps per minuteMedium: ~ steps per minuteFast: ~ steps per minute
9 Summary & Interpretation Oxygen expenditure is least while walking 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
10 Enter - The Idea of a ‘Preferred Rate’ A preferred rate of ambulation is a self-selected walking pace that an individual assumes that is most energy efficient
11 Clinical ImplicationSince 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 cardiovascular and motor control systems
12 Why is Gait More Efficient at Preferred Rate? What is the relationship between energy efficiency and a preferred rate of ambulation?
13 The Center of Gravity (COG) COG located at S1 - S2During preferred rate walking the COG approximates a sinusoidal curve from the:Sagittal perspective - no greater than a 2” peak-to-valley excursionFrontal perspective - no greater than a 2” medial-to-lateral excursion
15 Distortion of the Path of the COG A distorted path of the COG will require mechanical and motor control compensations that will:Disrupt normal timing of eventsOver-ride normal gait controlChange from ‘automatic’ to ‘manua’l control strategiesLead to over-correction of gait mechanics
17 A Simple ExampleWalking with a stiff-knee (“stiff-knee gait”) with a cylinder castDuring stance the HAT will vault over the fixed foot (especially during mid-stance)COG will be deflected higher than the usual 2” upward vertical displacement with increased energy cost
18 Who Walks with a Stiff Knee? Transient knee injury patient (e.g., surgical repair of a ligamentHemiplegic with loss of knee controlThe AK amputee with a locked-knee prosthesisThe BK amputee with poor knee controlShould we consider each case the SAME?
19 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 control system that accounts for gait mechanics without having to think about foot placement and other metrical details
21 An Everyday Occurrence You’re walking along 23rd Street, heading west toward your bus stopYou’re thinking about what was discussed in Kinesiology class todayYou’re also thinking that there is a lot a traffic and it’s going to take you forever to get home tonight...
22 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 maintaining reciprocal arm-swing?Are you thinking about...
23 Answer Probably NOT! Why? Your gait control is on ‘automatic pilot’ When do you have to think about gait control?When there’s a perturbation
24 Central Pattern Generator (CPG) CPG - a group of synaptic connections probably at the spinal cord level which 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 don’t have to think about it
25 EvidenceSpinalized (cord transected) cats suspended over a treadmill will walk with an alternating, striding quadripedal gaitHuman quadriplegics have also “walked” this way
26 CPG and Supraspinal Influence Gait perturbationsExample: Someone walks across your path from the side that you didn’t seeThere’s a need to take immediate corrective action to avoid a collisionSupraspinal centers appear to over-ride the CPG and switch to a ‘manual control’ strategy
27 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 control mechanism
28 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
29 Think About This...What’s one of the most common things heard during gait training in a PT clinic?
30 “Mr. Jones, while you’re walking, I want to go…”
32 What are some possible implications of this? Mr. Jones will be safe - probably won’t fall and break his hip (good news).Mr. Jones won’t sue you (good news).The path of the COG may be distorted (bad news).Energy cost may increase (bad news)Suppose Mr. Jones has a cardiac condition?
33 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).
34 Is it possible that...…going very slow might actually cause Mr. Jones to lose his balance and fall?Why?
35 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 flexionRight side of pelvis rotates medially preceding right hip flexionCOG moves over right foot after it’s advanced
36 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
37 Gait Training Scenario Mrs. Flanagan is standing in the 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…”
38 What wrong with this picture? Where is the patient’s COG relative to her base-of-support?What is probably the size of the 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?
39 Deficit-Oriented Gait Analysis Questions:Do diseases/injuries specifically manifest as a stereotypical gait pattern?orDoes the disease/injury lead to a deterioration of control parameters which cause gait deficits?
40 ResponseIf you believe the latter…it shouldn’t matter what the patient’s problem isIf you understand the consequence of the disease or injury (loss of motor control, weakness, damaged supportive structures, loss of a part of or an entire limb, etc.)...
41 …you should be able to anticipate or predict what impact a deficit has on gait irrespective of their state of injury or disease.
43 Analysis of Deficits Hip Extensors - Stance Early stance HS)Prevent hip flexion (jack-knifing)Early stance (HS - FF)Guide hip into flexion eccentricallyEarly stance HS) weakness/absenceHip/trunk collapses into flexionEarly stance (HS - FF)Trunk falls forward
45 Hip AbductorsPrevent contra-lateral hip from dipping greater thanStance-side abductors activeLoss of abductors:Static analysis - + Trendelenburg signDynamic analysis - weakness o f abductors manifests as ‘lurching gait’ (toward stance- side)
46 Analysis of Deficits Abductors - Stance Early stanceCOG shifts away from stance side LEIncreases moment arm of COG relative to stance side hipStance side abductors generate counter-rotational torque to prevent contra-lateral from dropping > 5-80Early stance weakness/absenceContra-lateral hip drops > 5-80Compensation is to lean (‘lurch’) over stance-side LE
48 Analysis of Deficits Quadriceps - Stance Early stance (HS - FF)Guides knee into 200 of flexion eccentrically (controls unlocking of the knee)Late stance (HR - TO)Controls for knee flexion (~400 at TO)Early stance weakness/absenceInability to absorb energyBucklingLate stance weakness/absenceKnee collapse into flexion -premature flexion into early swing - ‘rubber knee’
50 Analysis of Deficits Pre-tibial Group - Stance Early stance (HS - FF)Lowers forefoot to floor eccentricallyAfter forefoot contacts floor- pull tibia forward over footEarly stance weakness/absenceForefoot slaps to the floor - ‘drop-foot’ gaitLoss of forward pull of tibia
52 Analysis of Deficits Plantar Flexors - Stance Late mid-stanceConcentrically pulls tibia forwardLate stance (HR - TO)Provides propulsive thrust during push offEarly stance weakness/absenceLoss of forward pull of tibiaLoss of forward thrust - poor transition to early swing
53 Ankle Stability - Late Stance Ankle less stable and subject to injury (e.g., sprains) in plantar flexion vs.dorsiflexionPosterior trochlea in mortiseCollateral ligaments swing out of collateral positionPosition of ankle during push-off (late stance) = plantar flexed
54 Analysis of Deficits Peroneals - Stance Late stance (HR - TO)Dynamically provide collateral stability to ankle when plantar flexedSecondary plantar flexor for forward thrustLate stance weakness/absenceAnkle instability causing medial-lateral movementPotential for ankle injury - sprainsPoor transition from late stance to early swing
55 Analysis of Deficits Plantar Intrinsics - Stance Late stance (HR - TO)Provide medial - lateral stability to MTP joints (especially nos. 1 & 2) - cancels second degree of freedomImproves forward propulsion and transition to early swingLate stance weakness/absenceExcessive medial - lateral ‘shimmy’ of hindfoot during HRInefficient forward thrust
57 Analysis of Deficits Paraspinals - Stance Early stance (HS - FF) & late stance (HR - TO)Prevent forward flexion of trunk acting on pelvisEarly & late stance weakness/absenceTrunk falls forwardLoss of head and neck control
58 Analysis of Deficits Hip Flexors - Swing Late stance - early swing (acceleration)Forward flexion of femur working with plantar flexors to accelerate LE in early swingFunctionally shortens LE (with eccentric action of quadriceps and dorsiflexors) to prevent ‘toe-drag’Late stance - early swing weakness/absence of forward acceleration after TOToe may not clear the floor during swing throughCompensate with circumduction at hip
60 Analysis of Deficits Dorsiflexors - Swing Mid-to-late swing (deceleration)Affects ‘toe-up’ concentricallyFunctionally shortens LE during swing throughMid-to-late swing weakness/absenceLoss of ‘toe-up’CompensationIncreased hip flexion - ‘steppage gait’Circumduction at hip
62 Analysis of Deficits Hamstrings - Swing Late swing (deceleration)Decelerates tibial shankProvides for smooth transition between late stance and early swingLate swing weakness/absence‘Impact on terminal extension’ - knee slapped into extension or hyperextension
63 Gait in the Elderly Men - Murray, Kory & Clarkson Gait did not appear vigorous or laboredGait pattern did not resemble that of patients with CNS damageGait was guarded and restrained - attempt to maximal stability and security
64 Gait in the Elderly Men - Murray, Kory & Clarkson Gait resembled someone walking on a slippery surfacedecreased step & stride legnthwider dynamic BOSincreased lateral head movementdecreased rotation of pelvis
65 Gait in the Elderly Men - Murray, Kory & Clarkson toe/floor clearance distance slightly decreasedlower stance-to-swing ratiodecreased reciprocal arm swing more from elbow than shoulder
66 Spasticity and its Impact on Gait Spasticity - resistance to passive stretchResults from CNS (UMN) injury/diseaseIncreased source of uncontrolled/poorly controlled tensionProbably due to loss of inhibiting action of the CNSWhile tension production may be significant the time-rate-of-tension development may be delayed
67 Spasticity & Gait Spastic response may be caused by: Effects: Unexpected quick stretch of musclesFoot contact with floorSupraspinal overlayEffects:Restrict joint excursionDelay transition from one gait phase to the next
68 Spasticity & GaitDubo et al. showed that EMG activity of spastic muscles increased during mid-stance i.e., there was a loss of phasic control of muscles
69 Spasticity & Gait Examples QuadcricepsMay prevent knee from unlocking during interim between HS and FFKnee maintained in extension leading to a ‘vaulting’ over stance limb or circumduction of hipDisrupts (timing) transition to mid- and late stanceMay prevent LE bending during swing phase
70 Spasticity & Gait Examples Plantar flexorsIncrease in spastic tone may limit forward rotation of tibia between MS and POMay locate ground reaction force well behind knee causing significant flexion moment during late MS and knee buckling tendencyAnkle may be locked up during PO decreasing propulsive thrust forward - inefficient transition from TO to early swing
71 Spasticity & Gait Examples HamstringsMay limit forward swing of LE - decreasing step lengthMay prevent knee from reaching a terminally extended position just prior to HS
72 Gait Training - Questions If gait is controlled by a rate-dependent chain of synaptic connections at the spinal cord level (i.e., a CPG), is it possible for a PT to effect (physiological) changes in the gait control system?
73 Gait Training - Questions If gait is initiated (and sustained) as described previously (e.g., unloading of hip, pelvis rotates medially, COG loads over stance foot, etc.), how do we train patients to start walking?
74 Gait Training - Questions What impact will ‘assistive devices’ have on gait performance?Parallel barsWalkersBilateral & unilateral crutches and canesPTs using contact guarding from the side or behind
75 Gait Training - Questions If the rhythmic, symmetrical alternating characteristics of gait are triggered when a patient assumes their preferred rate, will gait symmetry and a ‘normal’ appearing gait be possible if the patient walks substantially slower than her preferred rate?
76 Gait Training - Questions Are all patients’ objectives concerning walking the same?Are your objectives for Ms. Walksalot, a 39 year old healthy female who broke her ankle two weeks ago in an intensive tennis match, the same as for Mr. Livesinathirdstorywalkup, a frail 87 year old male, with emphysema and a fractured, pinned hip?
77 Gait Training - Questions What’s the best thing a PT can say to their patient while gait training?...