Gait changes following Total Hip Replacement

Abstracts

146

gem a database developed from normal subjects who wcrc identically tested in our laboratory. Note that in 9 of the 10 Blounts patients, one limb was clearly more involved than the other; only data from the more deviant side was included in the group average. Left and right side data wcrc averaged in the 10th patient and in the normal subjects.

Parameter (units) Pm-op value Post-op value Age (years) 12.8 + 1.3 14.2 f 1.0 Body mass (kg) 97.6 + 20.2 103.4 f 18.9 Height (cm) 162.0 + 13.3 168.4 + 12.6 Tibia1 mechanical axis (dee) 24.2 f 6.5 0.6 k 0.5 Cadence (strides/xc) 10.873 f 0.106 10.873 + 0.107 Overall walkine soeed (m/s) 10.998f0.190 I1.042f0.179 Average knee varus (de& 21.6f 11.4 2.2 f 9.9 Peak knee varus (deg) 22.5+ 11.3 5.5 f 9.4 Average valgus moment (Nmkg)‘.’ 0.908 f 0.213 0.366 f 0.247 Peak valgus moment (N&kg)’ 1.009 f 0.206 0.498 f 0.278 Peak shear force at knee (N)’ 434.22216.1 141.3+ 171.5 Peak compressive force at knee (N)’ 886.5 f 216.4 1001.4 i 200.3 Notes: ‘Averaged during middle l/3 of stance phase. ‘Normalized to body mass in kg. ‘Estimated by rigid body, inverse dynamics analysis. ~

Fire 1: The mean knee angle data. Each curve is the mean of 54 (6 subjects; **“Strides” wcrc delineated using the maximum forward position of the heel.

18 Yolds

Subject 1

2

3 4 5 6 mean:

Table 1: Coefficient Ankle Knee 1.357 0.834 2.170 1.124 1.682 1.322 1.472 0.983 1.234 0.784 1.310 1.065 1.538 1.019

of Variation HiP 0.486 0.655 0.708 0.725 0.588 0.618 0.797

6 year olds

of the Angles (%) Subject Ankle 7 3.179 8 3.427 9 4.442 10 8.28 1 11 4.992 12 4.852 rncan: 4.862

9 strides).

Knee 2.415 2.398 3.086 4.038 2.342 2.779 2.843

Hip 1.298 1.377 1.913 1.831 2.038 1.154 1.602

Dllusaion From the results, it can bc seen that although the 6 year olds demonstrated essentially the same kinematic patterns as the young adults they did not demonstrate the same degree of neural contml. The fact that the mean patterns are similar suggests that the increased variability is not due to the obvious structural diffcrcnces between the hvo age groups. At age 18, however, the older girls have had a longer period of time free of changes in the bsngth of the long bones, allowing them more opportunity to perfect their movement pattcm. Thus, the incrcascd variability may reprcscnt an incomplete adaptation to changes in the structure and inertia of the limbs. Regardless of the source of the variability, it is a factor that should bc taken into account in studies of children when considering how many strides arc requited for analysis. References Sutherland, D.H. et al, Journal o/Bone and Joint Surgery, 62-A(3): 336-353,198O.

Session Cliiical

6: Pathological

Gait

Versus

Functional Outcomes of Surgical Intervention in Adolescent Blount’s Disease Patients Terry S. Horn, Ph.D., J.T. Killian. M.D.‘, and S.D. White, S.A.” ‘The University of Alabama at Birmingham “Children’s Hospital Health Services Foundation

lntroduetion Blount’s disease is a form of skeletal dysplasia which is typically manifested as obesity and excessive tibia vara in the adolescent. Persons with Blounts disease arc frequently relegated to a sedentary lifestyle, since increased loading of the medial tibia1 plateau during weight bearing can make everyday activities such as walking paintid. The conventional treatment of Blount’s disease is surgical realignment of the tibia by proximal valgus ostcotomy. Alteration of the long axis of the tibia to a straighter, more upright orientation prcsumably results in a favorable redistribution of compressive and valgus shear forces at the knee joint during the support phase of gait. The purpose of this investigation was to compart the results of a clinical measure of the degree of surgical correction, i.e. the restoration of the mechanical axis of the tibia as determined by radiographic imaging, to functional improvements in the knee joint loading pattern during dynamic weight bearing, estimated by biomcchanical analysis of walking gait. Methods Eighteen persons with a clinical diagnosis of Blount’s disease have undergone conA five camera motion analysis ventional three dimensional gait analysis in our laboratory. system (Vicon 370) was used to calculate lower extremity joint kinematic information, including coronal plane knee angle. These results were combined with ground reaction force data obtained from two strain gage-based, floor mounted force platforms (AMTl model OR6-5) to estimate segment endpoint force and torque values during the support axes of the tibiae were also determined by AiF’ phase of walking gait. The mechanical view radiography. Corrective surgery was then performed and external fixation applied to maintain tibia1 alignment. Patients spent an average of 11 weeks with external fixation hardware in place, followed by an aggressive rehabilitation program. Results At this time, preliminary data is available for 10 of 18 patients (5 males, 5 females) who have returned to unassisted walking and who have subsequently undergone follow-up gait evaluation. The clinical measurements and biomechenical parameters, as well as subject anthropometric information, were averaged within the prc-operative and postoperative conditions, These data arc presented below, along with baseline values extracted

I.

\

II

Normal value 33.3 + 3.6 78.6 + 4.6 174.4 + 4.1 o.o* 1.0 1 0.911 f 0.053 _ j1.293+0.074 3.4 313.6 6.8 + 4.0 0.261 f 0.049 0.526 f 0.033 211.5 f 47.8 869.2 f 59.8

Discussion Satisfactory surgical results were obtained in all cases, with average correction ofthe tibia1 mechanical axis of 24”. This clinical outcome did indeed correspond to improved coronal plane knee joint kinematics and kinetics during the weight bearing portion of the gait cycle. The average knee varus angle during the middle third of stance phase was decreased by a mean value of nearly 20”, with 8 out of 10 patients improving to within the normal range of values. Instantaneouspeok varus angle was similarly improved. Valgus loading at the knee joint was substantially lowered in all patients. with peak valgus moment decreased to within the normal range. Average valgus moment during midstance remained slightly increased in 6 out of 10 subjects, however. Estimated scgment endpoint shear force at the knee joint was significantly reduced, with the group mean actually falling below the normal range. Estimated compressive force apparently increased by nearly 13%. from an average of 886 N to over 1000 N. However. these patients were all in early adolescence. with mean growth of 6.4 cm in height and more than 5 kg (50 N) in weight between gait evaluations. When compressive force was normalized to the greater body weight at the time of follow-up testing, the increase was only about 6%.

Conclusions Post-operatively, cadence and overall walking speed were virtually unchanged, rcmainin8 slightly below normal. This may be due to residual muscle de-conditioning even following rehabilitation: the influence of well-established motor patterns; or the fact that temporospatial gait characteristics may be dictated by abnormally large thigh girth in these patients. The fact that average valgus moment tended to remain increased above normal post-operatively suggests that Blounts patients may be at risk for developing long-term disorders of the knee joint even following satisfactory surgid outcome. Gait Changes Following Total Hip Replacement S. Aiemian, BSc’ D. Than. PT,’ L. Kaul, PT.* P. Clarc, PT.* G. Hughes. MD’ and R. Zernicke, PhD’ *McCarg Center for Joint Injury and Arthritis Research. University ofCalgary. Calgary. Alberta. Canada TZN 4N I Introduction Total Hip Replacement (THR) is a highly successful surgical procedure for the treatment of a painful, diseased hip. Despite the dramatic decrease in pain and increase in function which normally occurs following osteoarthritis associated THR. many patients express a dissatisfaction with the continued physical limitations of their hip. One of the most noticeable gait abnormalities in THR candidates is the presence of a lurch over the painful hip. This lurching gait may be used to reduce the contact forces in the painful hip of the preoperative patients. by decreasing the hip abductor muscle force requirement. Estimates of hip contact forces show an increase from 3.4 times body weight (BW) prc-operatively to 3.7 BW at one year post-operatively (Brand et al.. 1980). Despite these changes. many patients continue to walk with an abnormal gait pattern. The purpose of this study is to identify which aspects of aberrant gait persist after THR. and whether or not the use of a cane corrects gait abnormalities. Methodology Eight patients. aged 64 * 2 years, were tested at three time periods: pm-operatively. 4 months post-operatively, and 8 months post-operatively. Patients were selected for requiring primary THR resulting from unilateral osteoarthritis of the hip. and were excluded for having (I J previous surgery to either hip, (2) pain or gait abnormality in non-operative limb or knee/ankle of the operative limb. or (3) pulmonary, cardiac or neuromuscular disease that might present potential risk to the patient during data collection or affect their ability to walk. At each time period. a clinical assessment and a gait analysis were performed. The clinical assessment included the Functional Capacity Assessment (FCA) questionnaire, joint range of motion, and a manual test ofjoint strength. The gait analysis included the acquisition of three-dimensional kinematics, ground reaction force data, and surface EMG from bilateral gluteus medius, tensor fascia lata. and erector spinae. Video data was digitized at 200 Hz, and ground reaction force data and EMG were digitized at 1000 Hz. Hip joint angles arc expressed thigh motion relative

Abstracts

to the lab coordinate system. Net moments at the lower limb joints were calculated using an inverse dynamic model of the lower extremity. The average of three trials were taken for the operative limb, with and without the use of a cane, and used for all comparisons.

(%BW*HT) (2). To minimize the effect of walking speed on the associated kinetics, a representative hial at about 1.O m/xc was chosen. The average walking speed for the patients and ~OIIII~S was 1.O f 0.1 m/w. Differences between the ACLD group with the “Quadriceps Avoidance Gait” and the normal group were identified using stodent’s f tests. A significance level of n < 0.05 was used.

Results The FCA revealed a dramatic decrease in pain past-operatively from 1.67 + 0.18 preoperatively to 0.25 f 0.16 by 8 months post-operatively, where pain is rated 0 to 3 (where 0 equals no pain, and 3 equals sevae pain). Clinical range of motion at the hip joint increased after THR. especially for flexion (85” f 6’ pm-operatively to 95” f 2” by 8 months postoperatively). Gait analysis results are presented in Table I. Both glutcus mcdius and tensor fascia lata increased duration of activity post-operatively, and the use of a cane decreased duration of muscle activity. Erector spinae recruitment was highly variable between subjects. but its activity decreased post-operatively.

Gait variable walking

speed (Ink)

I Torso Sway (“) Hip Flexion Hip Extension Hip Flexion Hip Extension Hip Abduction NC=no

(“) (“) Moment Moment Moment

caoe: C=cane:

Table 1. Longitudinal gait data for THR patients A MO. Post-Op. Pre-operati”~ 0 95--..I6 f 0-a 1.OOf0.04

NC C NC C NC C NC c NC c z

8.86 8.90 22.9 22.6 10.4 9.1 0.129 0.133 0.127 0.126 0.109 0.089

and moments

An&s

1.08 f 0.03 1.04 f 0.04

r

8.21 f 0.97 7.35 0.70 24.9 + 1.1 25.1 f 1.2 10.4 f 1.2 13.3 f 1.5 0.109 i 0.025 0.137 f 0.024 0.189 * 0.049 0.121 f 0.014 0.113f0.019 0.091 f 0.015

1.95 f 0.76 7.82 5.39 24.0 f 0.9 24.9 i 0.8 14.2 + 1.4 16.4 f. 1.6 0.212 + 0.020 0.203 f 0.028 0.114f0.013 0.094 f 0.014 0.101 f 0.022 0.096 i 0.024

I

are maximum

4WPCdop

pnop

Fig I. Maximal

f 0.68 0.99 f 1.3 f 1.5 * 2.2 f 1.6 + 0.027 * 0.035 i 0.020 f 0.022 iO.019 f 0.018

hip abduction

8 MO. Post-Op

1Ml f 0.05

0.92 * 0.05

moment during

values.

Moment

units are BWm.

8WPC6tOP

gait for THR patients.

Discussion The aim of THR is to relieve pain and restore the function of the diseased hip. The reSuh.~ of this pilot study showed a decrease in pain and lurch, and an increase in free walking speed and range of motion, both clinical and dynamic. Hip abduction moment (Fig 1) was higher preoperatively and at 4 months post-operatively than at 8 months post-operatively. The use of a cane in the contralateral hand reduced these moments to a level that remained relatively constant over the 8 month period. This may imply that THR patients use the cane to reduce the load on their hip abductors. This decrease in the demand of these muscles is reflected in the reduced time of activation at each time point with the use of a cane. The duration of activity increased post-operatively, suggesting that patients compensated for a decreased maximal abductor moment by maintaining a longer duration of a lower amplihlde muscle activity. Brand RA et al. Clinical

Orthopedics

Reference and Related Research,

147: 181-184,

141

ReSUlts Those patients with a “Quadriceps Avoidance Gait” walked with a decreased midstance knee flexion angle and an increased peak external hip flexion moment @<.OOl, ~1305) (Figure 2). Two distioct mechanisms were used when walking with a ‘*Quadriceps Avoidance Gait”. One mechanism consisted of decreasing the midstance knee flexion angle. 72% of the patients with a “Qwdriceps Avoidance Gait” had a decreased midstance knee flexion angle (more than 1 standard deviation below the normal mean). The midstance knee flexion angle was only 7 f 4 degrees in this group as compared to 19 f 5 degrees in the normal group @.ax). The second mechanism consisted of an increased peak external hip flexion moment. The remainder of the “Quadricqx Avoidawe” group without a decreased midstance koee flexion angle had a significantly increased peak external hip flexion moment as compared to normal (pc.001) and as compared to the “Quadriceps Avoidance” group with the decreased midstance knee flexion angle @<.OOl). In contrast, the peak external hip flexion moment in the group with a decreased midstance knee flexion angle was not significantly greater than normal @=.08). Discussion This study demonstrated that there are two possible mechanisms for walking with a “Quadriceps Avoidance Gait”. The tint mechanism is to reduce the midstance knee flexion angle. 72% of the patients had less knee flcxion during midstance as compared to those normals without a “Quadriceps Avoidance Gait”. By reducing the amount of knee flexion during midstance the patients reduce the demand for the quadriceps. This decreased demand for the quadriceps minimizes the anterior pull on the tibia, therefore helping to keep the knee stable. The second mechanism is to lean forward during midstance. 28% of the patients maintained a normal midstance knee flcxion angle, however, they increased their external hip flexion moment during midstance as compared to the normal group. Leaning forward during midstance tends to increase the hip flexion moment. By leaning forward the demand on the quadriceps is reduced. Since the majority of the hip extensors cross both the hip and knee joints, extending the hip has a tendency to flex the knee thoughout midstance. Knee l=l~xb”-Ex,B”dO” MOmen, $40 *.-. I : g pi ,,G : - - - NOrmPlBiphaas cm ;; . --P”Bdrepl g d *voldswe Gal’ z cs ; : ; 0.0 1;, I *

1980.

Acknowledgments This project was supported by the Canadian Orthopaedic Foundation, Hip Hip Hoaey and National), and the Alberta Heritage Foundation for Medical Research.

(Calgary

Mechanisms for the YQlr8drIceps Avoidance GalF Seen in AC!L Deficient Patients R.R. D.E. Hmwitz, T.P. Andriacchi, CA. Bush-Joscpb and B.R Bach, Jr. Rush-Presbytnian St. Luke’s Medical Center, Department of Orthopedic. Surgery Chicago, Illinois 60612 IlltlVdOCtIOll Past studies have shown that subjects with anterior crociate ligament deficiencies (ACLD) alter the manner in which they walk. More specifically, a deoreasc in the external knee flexion moment at midstance has been reported (1). In addition, some ACLD patients never achieve an external knee flexion moment during midstance. This type of gait has been referred to as a “quadriceps avoidance gait”. The objective of this study was to identify the mechanisms by which ACLD patients generate this “Quadriceps Avoidance Gait”.

Methodology The study group inch&d 18 ACLD patients who had a “Quadriceps Avoidance Gait” on their affected side. This +XD group consisted of 14 males and 4 females with an average age of 29 f 7 years sod an average time f?om injury to testing of 72 f 84 months. The control group included 18 age and gender matched normals who had a normal biphasic flexionextension moment (Figure 1). During the gait test patients walked at 3 self selected speeds. Lower extremity positions and ground reaction forces were measured with an optoelectronic system and force plate. Inverse dynamics was then used to calculate the lower extremity kinetics. All external moments were normalized to percent body weight multiplied by height

(I) Berchuck (2) Andriacchi

National

References M et al.: Journal of Bone and Joint Surgery, et al.: NATO AS1 E:83-102, 1985.

Institutes

of Health

72A: 871-877,

1990

Acknowled@nents Grant AR39432

Gait Characteristics in Primary Lateral Sclerosis L Doederlein, R Berghof, A Siebel, A Pappas Department of Orthopedic Surgery, University of Heidelberg,

Germany

Introduction Primary laleral sclerosis (familial spastic paraplegia/ PLS) is usually a disease of adolescents and adults marked by spasticity of the lower extremities Its prevalence is about 31100 000 It is mostly familial and slowly progressive The purpose of this study is to describe typical gait abnormalities for a group of patients and to make suggestion for therapy Methodology We investigated 7 patients (5 males and 2 females) between 14 and 36 years (mean the neurological diagnosis of PLS and slowly progressive spastic paraplegia, instrumented gait analysis, dynamic EMG and in 5 patients also kinetic measurement Noraxon, Kistler) There were no operative procedures before the investigation All were able to walk without assist& devices

23) with by 3-D (V&n, patients