1996 Knee Recurvatum in Gait, A Study of Associated Knee Biomechanics

8/9/2019 1996 Knee Recurvatum in Gait, A Study of Associated Knee Biomechanics

http://slidepdf.com/reader/full/1996-knee-recurvatum-in-gait-a-study-of-associated-knee-biomechanics 1/6

545

Knee Recurvatum in Gait: A Study of Associated Knee

Biomechanics

D. Casey Kemkan, MD, Lynn C. Deming, MS, PT, Maureen K. Holden, PhD, PT

ABSTRACT. Kerrigan C, Deming LC. Holden MK. Knee

recurvatum in gait: a study of associated knee biomechanics.

Arch Phys Med Rehabi l 1996;77:645-SO.

Objectives: To quantitatively evaluate peak knee extensor

torque values imparted to the posterior knee structures during

gait in patients with knee recurvatum compared with torque

values observed in control subjects, and to assess the predictive

value of the degree of knee hyperextension and other clinical

factors in estimating peak knee extensor torque.

Design: A retrospective analysis of clinical and quantitative

gait data obtained from patients and control subjects.

Settings:

A gait laboratory.

Subjects:

Forty-one consecutive patients with neurologically

based impairments presenting with knee hyperextension during

gait (52 limbs) and 46 able-bodied control subjects.

Main Outcome Measure:

Peak knee extensor torque dur ing

the stance period of the gait cycle.

Results: Although overall, the patient average peak extensor

torque was significantly greater (p < .oOl) than the control

subjects’ average value, knee extensor torques were within or

below a + I standard deviation range for control subjects in

25% (I 3) of limbs tested. Peak knee hyperextension angle was

a poor predictor of peak extensor torque; there was statistical

signifcance (coefficient .06 I, p < ,001) only for hyperextension

angles of ~4”. Multip le regression incorporating hyperexten-

sion angle and other clinical variables to predict peak knee

extensor torque resulted in an adjusted r’ of 33.

Conclusion:

Patients with knee recurvatum have variable

peak extensor torque value s associated with their knee hyperex-

tension. Knowle dge of knee hyperextension angle and other

clinical factors arc only partially useful in predicting a patient’s

peak knee extensor torque imparted to the posterior knee struc-

tures during walking.

0 I YY6 by the American C’ongrcw r Rehobil i fut ion Medicine

and the American Academy oj ’ f ’hysical Medicine ond Kehuhil i-

tut ion

D

YNAMI C KNEE RECURVA TUM, defined as hypercx-

tension of the knee during the stance period of the gait

cycle, is common in patients with a variety of neurologically

based impairments. It has been reported in nearly one half of

patients with stroke or traumatic brain injury in some clinical

study samples,’ ’ and in patients with cerebral palsy’ and polio-

myelitis.’ The disorder is typically ascribed to a combination

of quadriceps weakness, ankle plantar flexor spasticity. heel

cord contracture,’ quadriceps spasticity, and/or gastrocsoleus

weakness.” The dynamic knee recurvatum may be advanta-

geous in providing a mechanism to control an otherwise unsta-

ble limb during the stance period of the gait cycle. However, a

concern for patients with this disorder is that hyperextension

may produce an increased external extensor torque across the

knee.‘ placing the capsular and ligamentous structures of the

posterior aspect of the knee at risk for injury. Injury to these

tissues can cause pain, ligamentous laxity, or bony deformity.

which may lead to functional gait deficits.’ ”

Despite the pervasive nature of knee recurvatum and concern

for injury and secondary complications, there is no quantitative

information regarding the peak amounts of knee extensor torque

associated with rccurvatum. We became interested in this prob-

lem because of preliminary observations from clinical gait labo-

ratory analysis studies tha t although some patients with knee

recurvatum had high peak knee extensor torque va lues associ-

ated with their rccurvatum. other patients had surprisingly small

torque values. To date, there have been no reports regarding

how peak knee extensor torque values might vary with peak

hyperextension angle or other clinical factors. or how these

peak extensor torque values compare with values found in ablc-

bodied subjects who do not have knee recurvatum. Finally, there

is no quantitative infomm ation regarding the effect of treatments

such as an ankle-foot-orthosis (AFO) specifically aimed to re-

duce the knee extensor torque and risk for posterior knee struc-

tural injury.

Modern three-dimensional quantitative gait analysis allows

for measurement of knee joint extensor torque using force plate

information combined with inverse dynamic techniques applied

to kinematic data.‘,X Normally there is first an external flexor,

extensor. and then flexor torque about the knee during the stance

period of the gait cycle.‘.” We have observed, among patients

referred to our gait laboratory for clinical gait analysis, that

patients with knee hyperextension during the stance period may

or may not have excessive peak extensor torque values w hile

the knee is hyperextended. Patients with dynamic knee recurva-

turn who have only a small associated peak knee extensor torque

appear to have minimal stretch forces imparted to the posterior

knee structures, imp lyin g that the posterior structures arc not at

risk for injury. For these patients, knee hyperextension could

he considered a reasonable compensation, and treatments spc-

cificall y aim ed IO reduce knee hyperextensi on, such as specific

physical therapy techniques,‘“-” electrogoniometric fced-

hack,“.” ‘I or bracing across the knee”’ and/or ankle.“, “’ may

not he indicated. Other patients may have large knee extensor

torque values, implyi ng that a large, detrimental stretch force

is imparted to the posterior knee structures during walking.

The purposes of this study were IO ( I) quantitatively evaluate

the distribution of peak knee joint extensor torque values associ-

ated with knee recurvatum during gait in patients (without and

with an AFO if normally used) compared to those values ob-

tained in able-bodied (control) subjects, and (2) preliminarily

evaluate the predictive value of peak knee hyperextension angle

Arch Phys Med Rehabil Vol77, July 1996



646

BIOMECHANICS OF KNEE RECURVATUM, Ker r igan

and other clinical variables including age, gender, neurological

diagnosis, time s ince diagnosis, gait velocity , primary cause,

and timing of hyperextension in estimating peak knee extensor

torque.

METHODS

The kinematic and kinetic walking data from 41 consecutive

patients with knee recurvatum (52 limbs) secondary to neuro-

logical injury presenting to our Gait Laboratory were retrospec-

tively analyzed. Data from a group of 46 able-bodied subjects

(31 women and 15 men, age 29.6 2 8.7 years) were used for

controls. These control subjectshad been excluded for neurolog-

ical or musculoskeletal pathology. The retrospective analysis

and protocol for the control subjec ts were approved by our

Institutional Review Board. Patient subjects had neurological

injury secondary to stroke, traumatic brain injury, cerebral

palsy, multiple sclerosis, poliomyelitis, or lower motor neuron

spinal cord injury and had been referred for clinical evaluation

of their gait. The criteria for inclusion of patient subjects n the

present study were (1) knee hyperextension noted by motion

analysis to be greater than 0” beyond extension occurring during

some portion of the stance period, (2) knee recurvatum attrib-

uted to neurological injury confirmed by observational gait anal-

ysis performed by both a physiatrist and a physical therapist,

and (3) force plate data obtained for the involved limb. Forty-

four patients fit the first two criteria ; however, three were ex-

cluded because orce plate data could not be obtained secondary

to the other limb striking the force plate during the same elative

time frame. The mean age of the patient subjects was 35.9 years

with a standard deviation of 18.2 years; there were 24 men and

17 women. There were 32 right-involved lower extremities and

20 left-involved lower extremities (this included 11 subjects in

whom both extremities were involved). There were no signifi-

cant differences in demographics or in any of the variables

evaluated, including peak hyperextension angle and peak exten-

sor torque and veloc ity, between the patients with unilateral

involvement and patients with bilateral involvement (smallest

p value per unpaired t test was .23). Thus, the data from patients

with one and two knees involved were analyzed together, with

a correction (noted below) to account for the fact that not all

the data points for the patients with bilateral knee involvement

were independent.

For testing, each patient and control subject was instructed

to first stand and then walk barefoot at his or her own comfort-

able speed. Data from 3 walking trials per patient (the protocol

number of trials collected per each walking condition for clinical

gait laboratory analysis n our laboratory) and 5 trials per control

subject were averaged for the analysis. Data from an additional

3 trials while wearing an AFO were obtained in each patient

who normally wore one. An optoelectronic camera system” was

used to measure the three-dimensional coordinates of 1.5-cm-

hemispherical, infrared reflective markers attached to the pa-

tients’ and control subjects’ skin over the following bony land-

marks: the lower prominence of the sacrum, bilateral posterior

superior iliac spines, lateral femoral condyles, lateral malleoli,

and fifth metatarsals. Additional markers rigid ly attached to

wands were placed over the lateral femoral condyles, the ante-

rior tibia1 shafts, and the forefeet. Three-dimensional marker

position was collected at a sampling rate of lOOHz.“.” Four

video cameras were used with two cameras placed posterolater-

ally on each side of the subject. The accuracy of measure within

the working volume of a 2-m height, a 3-m length, and a l-m

width, was calibrated and predetermined before each patient

and control subject session o be within 0.2 C 2mm per 200mm

distance.

Ground reaction forces were measured synchronously with


the kinematic data at a sampling rate of 1OOHzusing two force

plates staggered along the walkway.” The locations of the force

plates in the global reference plane were predetermined by ac-

quiring coordinates of markers placed on their corners. A com-

mercialized protocol, termed SAFLo (Servizio di Analisi della

Funzionalita’ Locomotoria),” developed by Pedotti and Frigo,”

was used to calculate the kinematics and kinetics. The following

anthropometric measurements were taken according to the

SAFLo protocol to calculate the kinematics and kinetics: body

weight, pelvic width and height, thigh, foot, and lower leg

length, and intracondylar and intramalleolar width. Kine tics

were calculated using the force plate data and inverse dynamic

techniques described by Winter and Eng*Oper the SAFLo proto-

col. Torques were normalized for body weight and height and

are reported as external, in Newton meters per kilogram meters

(Nm/kgm). Gait velocities were obtained utilizing the kinematic

and force plate data and are reported in meters per second

(rdsec).

The timing of occurrence of knee recurvatum during the

stance period was recorded on the basis of the kinematic data

for each patient to be early if it occurred primarily in the first

third of the stance period, late if it occurred primarily in the

last third of the stance period, and continuous if it occurred

primarily in the middle third or was continuous throughout the

stance period. The most likely or primary cause for the knee

recurvatum, ie, quadricep weakness, ankle plantar flexor weak-

ness, ankle plantar flexor spasticity, heel cord contracture, or

mixed, was determined for each patient. The primary cause

determination was made on the basis of the gait and clin ical

evaluation, which included static manual muscle testing and

range of motion assessmentperformed by and agreed upon by

both the physiatrist and the physical therapist.

The patients’ velocity, peak knee hyperextension angle, and

extensor torque values were compared to control subject values

using unpaired t tes ts. Both the peak knee hyperextension angle

and torque values were compared with and without an AFO

(23 limbs) using paired t tests. Peak knee hyperextension angle

was plotted against peak knee extensor torque. The variables

of age, gender, neurological diagnosis, time since diagnosis,

veloc ity, peak knee hyperextension angle, primary cause, and

stance phase timing of hyperextension were evaluated as possi -

ble predictors of peak knee extensor torque using a piecewise

linear multiple regression analysis. The categorical variables of

gender, neurological diagnosis, primary cause, and timing of

recurvatum during stance were converted to dummy variables

for use in the regression. Since 11 of 52 subjects ’ data were

gathered on bilateral knees and, thus, not all data points were

independent, the HuberAVhite formula was used to supply ro-

bust standard errors for the coefficients in the significance tests

and confidence interval estimations.*‘~**

Several models were developed; at first all eight variables

and all levels were utilized. The final model reported in the

Results section does not include the four variables of age, gen-

der, time since diagnosis, and gait velocity as predictors of

peak knee extension torque, because they were found to be

nonsignificant contributors to the model. Overall, peak knee

hyperextension angle also was initi ally found to be a nonsig-

nificant contributor in predicting peak knee hyperextension

torque. Visual inspection of the graph of torque versus angle

(see fig 4), however, suggested a nonlinear, possible quadratic

function. Thus, peak hyperextension angle was converted into

two variables using a piecewise linear spline function, with a

breakpoint at 4”. Four degrees was chosen as the breakpoint

because t was the point that had the smallest mean square error.

A statistically significant correlation was found only for those

patients with hyperextension angles of 54”. The neurological



BIOMECHANICS OF KNEE RECURVATUM. Ker r igan

647

10

81 T

LX IQlm/Lr*m

EMT

sait Cycle

1

0.6

vELocllY 0 6

w-2 o4

Fig 1. Kne e flexor/extensor moms nt versus percentage of gait cycle:

Typical knee flexor/extensor mom ent p attern throughout the gait cycle.

The solid curve represents a typical patient ’s data,a nd the dashed curve

represents the mea n of control data. The horizonta l axis represents the

percentage of one gait cycle from 0 to 100%. The vertical axis represents

the moment, expressed in Newton meters per ki logram meters. The

vert ical l ine represents the division between the patient’s stance phase

and swing phase. FLX, f lexor; EXT. extensor.

02

Bo

diagnostic categorical variable was collapsed to two levels-

upper moto r neuron disorders and lower mo tor neuron disor-

ders. For the categorical var iable t iming of hyperextension dur-

ing the gait cycle , continuous t iming was used as the reference

group, with early and late t iming as the dumm y variables. For

the categorical var iable pr imary cause , plantarf lcxor weakne ss

was used as the reference group. The I test analyses and descrip-

t ive statist ics were performed using the statist ical software True

Epistat, ’ and the regression c alculations were performed using

the statist ical software Stata.“ Data are reported as means 2

one standard deviation. Signif icance was defined at p < .OS.

RESULTS

Figure 1 shows a typical knee f lexor/extensor mom ent p attern

throughout the gait cycle from one representative patient com-

pared with averaged control data. Figure 2 displays the distr ibu-

t ion of peak knee extensor torque values for the patient subjects

along with the mean + one standard deviation for both the

0.5

0.4

0.3

0.2

01

0

i

wmwa AFO WthrVO

Fig 3. IA) Patie nt versus control data for peak knee hyperextension

angle , where the vertical axis represents angl e in degrees. lB) Average

walkin g velocity for patien t versus control data, where the vertical axis

represents velocity in meters per second. (C) Patie nt data of peak exter-

nal extensor torque, with versus w ithout an AFO, where the vertical axis

represents torque in Newton meters per ki logram meters. Al l graphs

represent the mean (0 in A and B) - one standard deviation.

patient and control subject populations. The patient average

peak extensor torque, .27 t .I8 Nmlkg m, was signif icantly

greater ( /, < .OO l) than the control subjects’ average value of

.I3 2 .06 Nmlk gm. In 39 patient l imbs (75%), peak knee exten-

sor torques were higher than the control z one standard devia-

t ion range, in 10 limbs (19%) extensor torques were within this

range, and in 3 l imbs (6%) extensor torques were actually lower

than this range.

Figure 3 displays the patient versus control subjects for peak

knee hyperextension angle ( f ig 3A) and gait velocity ( f ig 3B).

For the patients, the peak knee hyperextension ranged from - 1”

to - 18” with a mean of -5.9” -C 4.7”. This was statist icallv

different @ < .OOl) from the average peak extension of 4.9” 1

3.9” observed in the control subjects. Th e average walking ve-

locity was signit icantly slower for the patients ( .42 z .21 m/

set) compared to the control subjects ( .77 -t .18m /sec, p <

.OOl). The differences in torque v alues with and without an

AFO arc shown graphically in f igure 3C. In those limbs for

Fig 2. Peak knee extensor torque distributio n for patie nt subjects lverti-

cal axis, no. of patients; horizontal axis, torque in Nmlkgm). The mean 2

one standard deviation for patient and control subjects is also i l lustrated.

Arch Phys Med Rehab il Vd 77, July 1996



BIOMECHANICS OF KNEE RECURVATUM, Ker r igan

Table 1: Means of Peak Extensor Torque, Walking Velocity, and Peak Hyperextension Angle as a Function of Diagnosis,

Timing of Hyperextension, and Primary Cause

N

Peak Extensor Torque

iNm/kgm), Mean (SD)

Walking Velocity

(m/set), M ean (SD)

Peak Hyperextension

Angle (7, Mean (SD)

Diagnosis

Traumatic brain injury

Cerebrovascular accident

Cerebral palsy, diplegia

Cerebral palsy, hemiplegia

Multiple sclerosis

Lower motor neuron spinal cord injury

Po l io

T im ing

Early

Late

Continuous

Primary causes

Plantarflexor spasticity

Plantarflexor contracture

Plantarflexor weakness

Quadriceps weakness

Mixed

10 ,277 t.167)

11 ,286 t.140)

3 .453 t.184)

5 .304 t.230)

2 .360 i .080)

6 .I23 t.152)

4

,320 t.076)

7 ,411 1.189)

22 ,176 t.141)

23 ,326 f.154)

7 ,286 c.247)

12 ,328 t.160)

21 ,198 c.166)

9

,343 c.125)

3 ,360 C.079)

.364 t.207)

,291 t.118)

,627 1.218)

,644 i .206)

,460 t.240)

,363 t.131)

,523 t.142)

,238 t.178)

,431 t.240)

.415 t.182)

.382 t.149)

,404 f.215)

.421 t.199)

.500 f.283)

,285 f.134)

4.6 (5.060)

7.0 (5.080)

6.0 (5.196)

6.4 (4.930)

2.5 t.500)

5.5 (5.577)

7.0 (2.944)

6.286 (3.817)

4.091 (3.265)

7.565 (5.558)

6.143 (5.429)

6.667 (5.433)

4.905 (4.182)

8.000 (4.583)

3.333 (3.215)

which the patient normally wore an AFO (n = 23), the knee

extensor torque was signif icantly less with the AFO (.20 + .I2

Nm/k gm) than without the AFO (.28 2.16 Nm /kgm , p < .OOl).

Table 1 show s the means of peak extensor torque, walking

velocity, and peak extension angle as a function of diagnosis,

t iming of hyperextension, and pr imary cause. Age, gender, ve-

locity, and t ime since diagnosis were not statist ically signif icant

predictors of peak knee hyperextension torque. Figure 4 demon-

strates a plot of peak knee hyperextension angle versus peak

knee extensor torque. Hyperextension angle was a statist ically

signif icant predictor of knee extensor torque only for those pa-

tients with hyperextension angles of 54” (regression coeff icient

.061, p < .OO l). A summ ary of the f inal regression model is

shown in table 2. Timing of hyperextension was a statist ically

signif icant predictor of knee extensor torque (p for simultaneous

test of all categories < .OO Ol). In particular, patients with late

stance phase t iming had signif icantly less extensor torque using

continuous t iming of hyperextension as the reference group.

Another statist ically signif icant predictor of peak knee extensor

torque was pr imary cause @ = .0034). In particular, patients

with quadriceps weakne ss had signif icantly greater extensor

torque values using plantarf lexor weakne ss as the reference

group. Diagnosis, collapsed into upper and lower m otor neuron

disorders, was another statist ically signif icant predictor of knee

07

I

. l

.

06

.

.

.

.

.

421 .

Fig 4. Peak knee external extensor torque versus peak hyperextension

angle in patient subjects. Torque is reported in Newton meters per ki lo-

gram meters; hyperextension angle is reported in degrees.

extensor torque. Patients with lower motor neuron disorder had

signif icantly less knee extensor torques using upper motor neu-

ron disorder as the reference group (p < .OO Ol). The multiple

regression model using these variables resulted in an 2 of .61

and an adjusted ? of .53, p < .OOl.

D ISCUSSION

In the patient l imbs studied, the average peak extensor torque

across the knee was twice the control average value; ho wever,

there was considerable overlap in the patient and control popula-

t ions. Seventy-f ive percent of the patient l imbs had torque val-

ues signif icantly higher than the control ? one standard devia-

t ion range, and 25% of patient l imbs had peak knee extensor

torque va lues within or below the control + one standard devia-

t ion range. The higher torque values are of concern because an

increase in the extensor mom ent at the knee is believed to

increase the r isk for damage to the poster ior passive structures

of the knee.’ The lower torque values may not be of concern,

and imply that for these patients knee hyperextension in the

involved limb is a reasonable and safe compensation to maintain

stabil ity in stance; treatments aimed specif ically to improve the

knee recurvatum may not be indicated.

Patients were asked to walk at their own comfortable speed,

which was found to be signif icantly slower on average com -

pared with that of the control subject population. If a patient

were to walk faster, he or she would have a greater e xtensor

torque acros s the knee.” This fac t is probably not clinically

Table 2: Final Regression Model to Predict Peak Knee Extensor Torque

95%

Regression Confidence

P

Predictor Coeffic ient Intervals

Va lue f

Hyperextension angle

.0008

For angles 5 4 ,061 (.030,.092)

Timing of hyperextension

<.OOOl

(continuous t iming as

reference)

Late stance phase t im ing

-.I70 l.243.T,095)

Primary cause (plantafflexor .0034

weakness as reference)

Quadriceps weakness ,162 (.078,.246)

Diagnosis (upper motor neuron

<.OOOl

injury as reference)

Lower motor neuron injury -.I58 (-.229,-,088)

r2 = .61, adjusted r2 = .53.

* For each of the predictor variables represented by 2 or more categories,

the reported p value is for the simultaneous test of al l categories.

Arch Phys Med Rehabil Vol7 7, July 1996



BIOMECHANKZS OF KNEE RECURVATUM, Ken igan 649

significant because an individua l normally walks at his or her

most comfortable speed.” Thus, the measured peak extensor

torque dur ing comfortable walking speed is likely a true reflec-

tion of the extensor torque imparted to the posterior structures

of the knee during usual walking activity.

Although overall, the peak knee extensor torque values were

less with an AFO than without an AFO for those patients who

routinely used an AFO, some patients had little or no reduction

in peak knee extensor torque with the AFO ( fig 30. Conceiv-

ably, in these cases the AFO may have acted primarily to reduce

the energy requirement of walking” rather than to reduce the

extensor momen t at the knee. Quantitative gait analysis may be

useful to assess the benefits of an AFO with respect to both knee

extensor torque and overall biomcchanical gait performance.”

Similarl y, gait analysis may be useful for evaluating the effects

of any other treatments, such as stretching or strengthening

exercises, specifica lly aim ed to improv e knee hypcrcxtcnsion

and peak knee extensor torque.

The degree of peak knee hyperextension angle by itself was

not a useful predictor of peak knee extensor torque. Moreover,

peak knee hyperextension angle combined with other clinical

variables were only partly helpful in predicting the peak knee

extensor torque for a particular patient. The clinical variables

of age, gender, gait velocity, and time since neurological injury

were not useful in predicting knee extensor torque. Althoug h

the variables knee hyperextension angle, diagnosis, timing. and

primary cause helped to predict the knee extensor torque, these

factors explained only about half the variance of the torque

values. The relationship between peak knee hyperextension

angle and peak knee extensor torque was statistically significant

only for those hyperextension angles of 54”. This statistically

significant relationship is likely not clinically significant be-

cause it is probably not possible to ascertain the hyperextension

angle within the range of 0” to 4” from observational or video

analysis alone.

The poor relationship between the clinical variables and knee

cxtcnsor torque could be due in part to a small sample size,

given the number of variables analyzed. However, we believe

a more likely reason for the poor relationship is the fact that

there arc complex interactions and compensations about the

trunk. hip,and ankle, making it difficult to predict the knee

extensor torque . For instance, the extensor torque could bc rc-

duccd in the face of a large amount of knee hypcrcxtension if

foot contact is relatively calcaneal or if the trunk is relatively

hyperextended during the knee recurvatum. Conversely, relative

forefoot contact, a relatively plantarflexed ankle, and/or a rela-

tively flexed trunk at the time of knee hyperextension would

tend to increase the peak extensor torque across the knee. The

interactions of these potential events arc likely important in

determinin g the peak knee extensor torque, yet they arc diflicult

to evaluate from clinical evaluation alone. These findings tend

to support the role for quantitative gait analysis to study knee

extensor torque on a routine basis for patients with knee hyper-

extension to evaluate an individual patient’s risk for posterior

knee structural injury.

The complex interactions about multip le joints might also

explain some of the statistically significant findings as well.

such as why patien ts with quadriceps weakness as the primary

cause for the knee recurvatum had greater knee extensor torque

values compared with the reference group of patients with gas-

trocsoleus weakness. A plausible reason for this statistically

significant finding could be that those patients with gastrocso-

leus weakness tend to have relatively calcaneal foot contact5

compared to patients with quadriceps weakness. A relative cal-

caneal foot contact would tend to reduce the knee extensor

torque. The finding that hyperextension occurring late rather

than early or continuous during the stance period was associated

with less peak knee extensor torque can be attributed to similar

complex interactions. At terminal stance, the hip is hypercx-

tending and the ankle begins to dorsiflcx. The trunk w eight

becomes more anterior to the knee, but the overall weight im-

parted to the limb reduces as weight is being transferred to the

other limb.

It was not expected that patients with lower motor neuron

disorder would have statistically significant lower peak extensor

torques than patients with upper motor neuron disorder. Patients

with upper motor neuron disorders commonly have an extensor

synergy patte rn with quadriceps overactivity result ing in re-

curvatum. Whi le thi s synergy may affect the hyperextensio n

angle, it may or may not affect the knee extensor torque. Com-

monly, patients with upper motor neuron injury have weakness

and/or contracture in muscle/tendon groups both proximal and

distal to the knee. For example, it is typical to see a combination

of hip flexor and heel cord contractures in patients with upper

motor neuron injury. Both of these factors place the ground

reaction force more anterior to the knee, thus increasing the

external extensor moment at the knee. Although patients with

upper motor neuron injury had relatively higher knee extensor

torques, perhaps these patients have some protection from the

knee extensor torque. The extensor torque is countered by the

posterior structures of the knee. This include s the posterior cap-

sule and the posterior cruciate ligamen t. It also includes the

long hamstring and gastrocnemius muscles a nd tendons. These

muscles are typically active during i nitia l to midstance and

midstancc to terminal stance respectively.” Many patients with

upper motor neuron injury have excessive activity in these mus-

cles during mid to terminal stance,5.?h which could b e greater

than the overactivity commonly present in the quadriceps, per-

haps mitigat ing the increased external knee extensor torque.

Patients with lower motor neuron injury, on the other hand,

may have less muscle activity than otherwise and thus might

have less opportunity for protection against the extensor torque.

In conclusion, the results of the study demonstrate that there

is considerable range of knee extensor torque values in patients

with knee recurvatum. Althoug h overall, patients have higher

peak knee extensor torque values compared with control sub-

jects, approximately one quarter of patient limbs have knee

extensor torque values in the control + one standard deviation

range. The results i mply that knowledge of clinical factors,

including peak knee hypcrextcnsion angle, can explain only

about half of the variance in peak knee extensor torque. Al-

though this was a small sample size for the number of variables

analyzed, a likely reason for the poor relationship between clini-

cal factors and knee extensor torque is that complex interactions

about the trunk, hip, knee, and ankle make it difficult to predict

peak knee extensor torque. The findings of this study support

routinely using quantitative gait analysis to evaluate peak exten-

sor torque in patients with knee recurvatum and to assess the

effects of treatments such as an AFO aimed at reducing the

torque.

Acknowledgement: The authors acknowledge Thomas A. Rihaudo.

MS. for his technical assistance and Richard Goldstein. PhD, for his

statistical assistance.

References

I Hoguc RE, McCandless S. Genu recurvalum: auditory biofeedback

treatment for adult patients with stroke or head injuries. Arch Phys

Med Rchabil 1983;64:368-70.

2. Knutsson E. Richards C. Different types of disturbed motor control

in gait of hemiparetic patients. Brain 1979; 102:405-30.

3. Simo n S R. Deutsch SD. Nuzzo RM. Mansour MJ, Jackson JL.

Koskinen M, ct al. Genu recurvatum in spastic cerebral palsy: report

Arch Phys Mad Rehabil Vol77 , July 1996



650 BIOMECHANICS OF KNEE RECURVATUM, Ker r igan

on findings by gait analysis. J Bone Joint Surg Am 1978;60:882-

94.

4. Irwin CE. Genu recurvatum followin g poliomyelitis: a controlled

method of operative correction. JAMA 1942; 120:277-80.

5. Perry J. Gait analysis: normal and pathological function. Thorofare

(NJ): Slack, 1992.

6. Morris ME, Matyas TA, Bach TM, Gold ie PA. Electrogoniometric

feedback its effect on genu recmvatum in stroke. Arch Phys Med

Rehabil 1992;73:1147-54.

7. Winter DA. Kinemat ic and kinetic patterns in human gait: variabil-

ity and compensating effects. Hum Mov Sci 1984; 35-76.

8. Harris GF, Wertsch JJ. Procedures for gait analysis. Arch P hys Med

Rehabil 1994;75:216-25.

9. Kadaba MP, Ramakrishnan HK, Wootten ME, Gainey J, Gorton

G, Cochran GVB. Repeatability of kinematic, kinetic, and electro-

myographic data in normal adult gait. J Orthop Res 1989;7:849-

60.

IO. Bobath B. Evaluation and management of adult hemiplegia. Lon-

don: Will iam Heinemann Medical Books, 1978.

I I. Knott M, Voss DE. Proprioceptive neuromuscular facilitation: pat-

terns and techniques. New York: Harper & Row, 1968.

12. Kohe il R, Mandel AR. Joint position biofeedback facilitation of

physical therapy in gait training. Am J Phys Med 1980;59:288-97.

13. Basaglia N, Mazzini N, Bold &i P, Bacciglieri P, Contenti E, Ferra-

resi G. Biofeedback treatment of gem-recurvatum using an electro-

goniometric device with an acoustic signal. Stand J Rehabil Med

1989;21:125-30.

14. Famcombe PM. The Swedish Knee Cage: managem ent of the hy-

perextended hem iplegic knee. Physiotherapy 1980;66:33-4.

15. Isakov E, Mizrahi IO, Susak Z. The control of genu recurvatum by

combining the Swedish Knee-Cage and an ankle-foot brace. Disabil

Rehabi l 1992; 14: 187-91.

16. Rosenthal RK, Deutsch SD, Miller W, Schumann W, Hall JE. A

fixed-ankle, below-the-knee orthosis for the managem ent of genu

recurvatum in spastic cerebral palsy. J Bone Joint Surg Am 1975;

57545-7.

17. Ferrigno G, Pedotti A. ELITE: a digital dedicated hardware system

for movement analysis via real time TV processing. IEEE Trans

Biomed Eng 1985;32:943-50.

I8

I9

20

21

22

23

24

25

26

Borghese NA, Ferrigno G. An algorithm for 3-D automatic move-

ment detection by means of standard TV cameras. IEEE Trans

Biomed Eng 1990;37:1221-5.

Pedotti A , Frigo C. Quantitative analysis of locomotion for basic

research and clinical applications. Func Neurol S uppl 1992;7:47-

56.

Winter DA, E ng P. Energy generation and absorption at the ankle

and knee during fast, natural, and slow cadences. Clin Orthop Rel

Res 1983; 175:147-54.

Huber PJ. The behavior of maximum likelihood estimates under

non-standard conditions. Proceedings of the Fifth Berkeley Sympo-

sium on Mathemat ical Statistics and Probability; 1965 June 21-

July 18. Berkeley, CA: University of California Press, 1967; 1:221-

33.

White H. A heteroskedasticity consistent covariance matrix estima-

tor and a direct test for heteroskedasticity. Econometrica 1980;48:

817-30.

Gonzalez EG, Corcoran PJ. Energy expenditure during ambulatio n.

In: Downey JA, Myers SJ, Gonzalez EG, Lieberman JS, editors.

The physiologic basis of rehabilitat ion medicine. Ed. 2. Stoneham :

Butterworth-Heineman, 1994:413-46.

Corcoran PJ, Jebsen RH, Brengelm ann GL, Simons BC. Effects of

plastic and metal leg braces on speed and energy cost of hemiparteci

ambulat ion. Arch Phys Med Rehabil 1970;51:69-77.

Keniga n DC, Viramontes BE, Corcoran PJ, LaRaia PJ. Measured

versus predicted vertical displacement of the sacrum during g ait as

a tool to measure biomechanical gait performance. Am J Phys Med

Rehabil 1995;74:3-8.

Keniga n DC, Gronley J, Perry J. Stiff-legged gait in spastic paresis:

a study of quadriceps and hamstrings muscle activity. Am J Phys

Med Rehabi l I99 I ; 70:294-300.

Suppliers

a. Bioengin eering Technology Systems, Via Capecelatro, 66, 20148

Milan, Italy.

b. Advanced Mechanical Technology Inc., AMTI, I5 I California Street,

Newton, MA 02 158.

c. Epistat Services, 2011 Cap Rock Circle, Richardson, TX 75080.

d. Stata Corporation, 702 University Drive East, College Station, TX

77840.


1996 Knee Recurvatum in Gait, A Study of Associated Knee Biomechanics

Documents

Transcript of 1996 Knee Recurvatum in Gait, A Study of Associated Knee Biomechanics