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
26、s, loss of a part of or an entire limb, etc.).,you should be able to anticipate or predict what impact a deficit has on gait irrespective of their state of injury or disease.,Hip Extensors - Stance,Analysis of Deficits Hip Extensors - Stance,Early stance ( HS) Prevent hip flexion (jack-knifing) Earl
27、y stance (HS - FF) Guide hip into flexion eccentrically,Early stance ( HS) weakness/absence Hip/trunk collapses into flexion Early stance (HS - FF) Trunk falls forward,Hip Abductors - Stance,Hip Abductors,Prevent contra-lateral hip from dipping greater than 5 - 80 Stance-side abductors activeLoss of
28、 abductors: Static analysis - + Trendelenburg sign Dynamic analysis - weakness o f abductors manifests as lurching gait (toward stance- side),Analysis of Deficits Abductors - Stance,Early stance COG shifts away from stance side LE Increases moment arm of COG relative to stance side hip Stance side a
29、bductors generate counter-rotational torque to prevent contra-lateral from dropping 5-80,Early stance weakness/absence Contra-lateral hip drops 5-80 Compensation is to lean (lurch) over stance-side LE,Quadriceps - Stance,Analysis of Deficits Quadriceps - Stance,Early stance (HS - FF) Guides knee int
30、o 200 of flexion eccentrically (controls unlocking of the knee) Late stance (HR - TO) Controls for knee flexion (400 at TO),Early stance weakness/absence Inability to absorb energy BucklingLate stance weakness/absence Knee collapse into flexion -premature flexion into early swing - rubber knee,Pre-T
31、ibial Group - Stance,Analysis of Deficits Pre-tibial Group - Stance,Early stance (HS - FF) Lowers forefoot to floor eccentrically After forefoot contacts floor- pull tibia forward over foot,Early stance weakness/absence Forefoot slaps to the floor - drop-foot gait Loss of forward pull of tibia,Plant
32、ar Flexors - Stance,Analysis of Deficits Plantar Flexors - Stance,Late mid-stance Concentrically pulls tibia forward Late stance (HR - TO) Provides propulsive thrust during push off,Early stance weakness/absence Loss of forward pull of tibia Loss of forward thrust - poor transition to early swing,An
33、kle Stability - Late Stance,Ankle less stable and subject to injury (e.g., sprains) in plantar flexion vs.dorsiflexion Posterior trochlea in mortise Collateral ligaments swing out of collateral positionPosition of ankle during push-off (late stance) = plantar flexed,Analysis of Deficits Peroneals -
34、Stance,Late stance (HR - TO) Dynamically provide collateral stability to ankle when plantar flexed Secondary plantar flexor for forward thrust,Late stance weakness/absence Ankle instability causing medial-lateral movement Potential for ankle injury - sprains Poor transition from late stance to early
35、 swing,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 freedom Improves forward propulsion and transition to early swing,Late stance weakness/absence Excessive medial - lateral
36、shimmy of hindfoot during HR Inefficient forward thrust,Paraspinals -Stance,Analysis of Deficits Paraspinals - Stance,Early stance (HS - FF) & late stance (HR - TO) Prevent forward flexion of trunk acting on pelvis,Early & late stance weakness/absence Trunk falls forward Loss of head and neck contro
37、l,Analysis of Deficits Hip Flexors - Swing,Late stance - early swing (acceleration) Forward flexion of femur working with plantar flexors to accelerate LE in early swing Functionally shortens LE (with eccentric action of quadriceps and dorsiflexors) to prevent toe-drag,Late stance - early swing weak
38、ness/absence of forward acceleration after TO Toe may not clear the floor during swing through Compensate with circumduction at hip,Dorsiflexors - Swing,Analysis of Deficits Dorsiflexors - Swing,Mid-to-late swing (deceleration) Affects toe-up concentrically Functionally shortens LE during swing thro
39、ugh,Mid-to-late swing weakness/absence Loss of toe-up Compensation Increased hip flexion - steppage gait Circumduction at hip,Hamstrings - Swing,Analysis of Deficits Hamstrings - Swing,Late swing (deceleration) Decelerates tibial shank Provides for smooth transition between late stance and early swi
40、ng,Late swing weakness/absence Impact on terminal extension - knee slapped into extension or hyperextension,Gait in the Elderly Men - Murray, Kory & Clarkson,Gait did not appear vigorous or labored Gait pattern did not resemble that of patients with CNS damage Gait was guarded and restrained - attem
41、pt to maximal stability and security,Gait in the Elderly Men - Murray, Kory & Clarkson,Gait resembled someone walking on a slippery surface decreased step & stride legnth wider dynamic BOS increased lateral head movement decreased rotation of pelvis,Gait in the Elderly Men - Murray, Kory & Clarkson,
42、toe/floor clearance distance slightly decreased lower stance-to-swing ratio decreased reciprocal arm swing more from elbow than shoulder,Spasticity and its Impact on Gait,Spasticity - resistance to passive stretch Results from CNS (UMN) injury/disease Increased source of uncontrolled/poorly controll
43、ed tension Probably due to loss of inhibiting action of the CNS While tension production may be significant the time-rate-of-tension development may be delayed,Spasticity & Gait,Spastic response may be caused by: Unexpected quick stretch of muscles Foot contact with floor Supraspinal overlay Effects
44、: Restrict joint excursion Delay transition from one gait phase to the next,Spasticity & Gait,Dubo et al. showed that EMG activity of spastic muscles increased during mid-stance i.e., there was a loss of phasic control of muscles,Spasticity & Gait Examples,Quadcriceps May prevent knee from unlocking
45、 during interim between HS and FF Knee maintained in extension leading to a vaulting over stance limb or circumduction of hip Disrupts (timing) transition to mid- and late stance May prevent LE bending during swing phase,Spasticity & Gait Examples,Plantar flexors Increase in spastic tone may limit f
46、orward rotation of tibia between MS and PO May locate ground reaction force well behind knee causing significant flexion moment during late MS and knee buckling tendency Ankle may be locked up during PO decreasing propulsive thrust forward - inefficient transition from TO to early swing,Spasticity &
47、 Gait Examples,Hamstrings May limit forward swing of LE - decreasing step length May prevent knee from reaching a terminally extended position just prior to HS,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
48、 it possible for a PT to effect (physiological) changes in the gait control system?,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?,G
49、ait Training - Questions,What impact will assistive devices have on gait performance? Parallel bars Walkers Bilateral & unilateral crutches and canes PTs using contact guarding from the side or behind,Gait Training - Questions,If the rhythmic, symmetrical alternating characteristics of gait are trig
50、gered 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?,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?,
