Effect of a Walking Program on Gait Characteristics in Patients with Ost eoart hritis

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1 Effect of a Walking Program on Gait Characteristics in Patients with Ost eoart hritis M.G.E. Peterson, P.A. Kovar-Toledano, J.C. Otis, J.P. Allegrante, C.E.C. Mackenzie, 3. Gutin, and M.A. Kroll This paper reports the results of a study of the gait of 102 patients with osteoarthritis of the knee. Functional status was measured by a 6-min test of walking distance; the stride characteristics associated with the wal,k test were assessed. Stride characteristics were meceured by a Stride Analyzer. Patients were randomized to an 8-week educational and walking prograin (the intervention group) or to a weekly telephone survey [the control group]. The intervention group patients had a 35% increase in walking distance [P <: ) and increases of 9.1% in stride length at free walking speeds (P < 0.007) and 17% in stride length at fast walking speeds (P < 0.01) compared to the control group. The results of this study have shown that the walking and educational program was effective in improving gait function in patients with osteoarthritis of the knee..- M.G.E. Peterson, PhD, is statistician, J. Otis, PhD, is Director of the Motion Analysis Laboratory, P.A. Kovar-Toledano, EdD, is Research Associate, and B. Gutin, PhD, is on sabbatical at The Hospital for Special Surgery, New York, New York. J.P. Allegrante. PhD, is Associate Professor of Health Education and Clinical Public Health in Sociomedical Sciences at Columbia University, New York, New York and Director of Educational Research and Development at Cornell Arthritis and Musculoskeletal Disease Center, New York, New York. C.R. Mackenzie, MD, is Associate Professor of Clinical Medicine at Cornell University, Ithaca, New York. M.A. Kroll, MA, PT (deceased], was Research Associate at the Motion Analysis Lab-,iratory, The Hospital for Special Surgery, New York, New York. B. Gutin, PhD, is currently Professor of Exercise Science at Medical College of Georgia, Augusta, Georgia. Address correspondence to M.G.E. Peterson, PhD, Department 'jf Biomechanics, The Hospital for Special Surgery, 535 East 70th :St, New York, NY Submitted for publication February 17, 1992; accepted May 18, by the Arthritis Foundation. Key Words: Gait; Osteoarthritis; Walking; Pdient education. The primary goal in the clinical management of osteoarthritis (OA) is to help improve the functional status of ihe patient. Treatment has traditionally involved analgesic and anti-inflammatory agents, range-of-motion exercises, and the avoidance of weight-bearing activity. In refractory cases, orthopedic surgical intervention has become common. Recent studies have found that walking may be a safe and effective form of exercise for improving aerobic capacity and physical activity, without triggering joint flares [l-31. In a separate randomized trial [4], we demonstrated that a supervised program of fitness walking for patients with OA of the knees improved functional activity without increased pain or use of medication. This study was designed to examine the gait characteristics of OA patients assigned to two groups. The intervention group was enlisted in a walking and education program; the control group did not have the program. Stride characteristics measured at baseline and postintervention were compared to determine if changes occurred in the subjects' gait. Velocity (m/ min], cadence (stepdmin), and stride length (m) were measured. The criteria for an improvement in gait was a significant increase in velocity without a significant decrease in stride length. SAMPLES AND METHODS Recruitment A total of 102 patients were recruited from cooperating physicians at the Hospital for Special Surgery, /93/$

2 12 Peterson et al. Vol. 6, No. 1, March 1993 outpatient rheumatology and orthopedic clinics at the hospital, and volunteers from various communitybased sites in the vicinity of the hospital. The subjects were eligible if they had a documented diagnosis of chronic, stable primary OA of the knee joint(s) and were at least 40 years old. Qualifying OA was defined by: 11 ] at least a 4-month history of symptomatic knee pain during weight-bearing activities; (2) radiographic evidence of OA of the knee joint(s) as demonstrated by joint space narrowing, marginal spur formation, or subchondral cyst formation: and (3) use of nonsteroidal anti-inflammatory drugs 2 or more days per week. If a patient was currently enrolled in a regular program of physical exercise at the time of the pretrial interview, they were excluded from the study. We defined participation in a regular program as engaging in routine physical activity three or more times per week for at least 30 min or attending an exercise class. Data collected on each subject included gait characteristics and demographic data. Program Patients were randomized to intervention or control groups. The intervention group attended an 8-week, hospital-based educational and walking program, described in detail elsewhere [5]. Members of the control group were phoned each week for a report on health and exercise activities. The same questions were answered by the intervention group each week during class. The questions involved physical activity such as how many blocks walked or stairs climbed per day during the past week. The intervention was modelled after such successful programs as the Arthritis Self-Help course and the Rockport Walking program [5-71. The sessions included warmup, strengthening, and cooldown exercises. The course began with an easily mastered frequency and intensity of walking. At first, subjects walked three times a week for 5 min and always so that knee pain was not exacerbated. Each walking session was increased by 2.5 rnin per week, if tolerated, until the subject walked four times a week for 30 min each stssion. Patients were always self-paced. They were instructed to walk so that they could talk easily without becoming breathless. Everyone in the two groups had antalgic gaits. Four people used canes and three of these were in the intervention group. Because subjects were unilateral or bilateral we did not measure asymmetry. The principal method of assessing functional status was a 6-min test of walking distance performed by patients according to the method of Guyatt et al. [8,9]. The test was conducted on a vinyl tile surface hallway that comprised a rectangular pathway of 114 ft. Start- ing from a marked point, the patients traversed this hallway for 6 min. Attrition Of thie five dropouts from the intervention group, one patient dropped out for arthritis-related reasons (the patient underwent a total knee rep1acemt:nt) and four dr,opped out due to nonarthritis-related factors, including one death that was judged to be unattributed to the intervention and one hip fracture due to a fall during a program session. Of the five dropouts from the control group, one patient dropped out due to a fractured hip following a fall and the four remaining patients were unable to return for post-testing because of nonarthritis-related reasons. Subjects Forty-seven patients in the intervention group completed the 8-week walking program and were retested; 44 of the controls completed the walk and the gait analysis. Subjects ranged in age from 40 to 89 years with a mean age of 69.4 years. Gender, race, education, and employment characteristics were not significantly different in the two groups. Inter-group differences in marital status were statistically significant at baseline (xz = 7.49, df = 1, P = 0.006), i.e., more people in the intervention group were married. The two study groups were alike on measures of height and weight. The average height by group was k 11.3 cm for intervention subjects and cm for controls. The mean body weight by group was kg for intervention subjects and Ikg for the control group. There were no inter-group differences in patients comorbid diagnoses or in self-reported medic, d 1 man- agement of these conditions. The mean number of years diagnosed with OA was 12.0 k 11.8 for the intervention group and for the control group. Eighteen patients in the intervention and 29 in the control group had unilateral joint involvement (xz = 4.7, df == 1, P = 0.03). Inter-group differences at baseline were not significant (P > 0.05) for sociodemographic characteristics (except for marital status), clinical data, comorbidity, arthritis history, measures of functional status (except for gender differences in the 6-min walk test], and stride characteristics (except for gender differences in stride length and velocity at free and fast walking speeds). Outcome Measures Stride characteristics were assessed using the VA- Rancho Footswitch Stride Analyzer Mark 11, accord-

3 Arthritis Care and Research Gait in Osteoarthritis 13 TAIBLE 1 Outcome Measures at Baseline and Post-Intervention Baseline Post-intervention Intervention Control Intervention Control group group group group Measure (n = 47) (n = 44) Pa (n = 117) (n = 44) Pb P 6-min walk (m] * _ t 125 <0.001.:0.001 Free velocity (ndmin) 56 f f f f Free cadence (sf eps/min) 101 f f i Free stride (m) 1.1 i f i Fast velocity (m/min] 76 i f k i Fast cadence (si eps/min] 122 i ? ? f Fast stride [m] 1.2 f i i f Values are given as mean? standard deviations. Baseline comparisons between intervention and control groups, P value from t-test comparison. Post-test-baseline comparisons between intervention and control groups. Within group P values for intervention group ing to tle method of Kroll et al. [lo]. The footswitch stride analysis provides an objective measurement of gait characteristics that are highly correlated to the observed antalgic maneuvers of patients with arthritis [10,11]. Patients foot-floor contact patterns were recorded as they walked the middle 6 m of a 10-m walk. Subjects were instructed to walk at two nominal speeds that were self-selected when prompted by examiner cues of fast and free. Two walks at each speed were conducted. The system s microprocessor computed the patients stride characteristics in absolute quantities. Because the mean values of stride characteristics were similar at each walking speed, the trials with the greater velocity at each speed were selected and those associated characteristics were included in the analysis. Measurements of single-limb support times were neither reported nor used in the analysis, because the asymmetry of the pathology, i.e., multiple joint involvement, would yield highly variable results. Data Analysis A.11 data are reported as mean k standard deviation. Statistical analyses using xz and t-tests were performed to test for group differences at baseline. Twoway repeated measures analysis of variance was used to analyze the significance of pre- to post-test changes in distance walked and velocity. The Kruskal-Wallis, the Mann-Whitney, and t-tests were used to compare before and after changes between groups. The overall alpha was set at 0.05 and a Bonferroni adjustment for multiple comparisons was used to adjust individual probabilities with an alpha of RESULTS Outcome Measures Table 1 shows the results of the outcome measures in the two study groups at baseline and postintervention. The pain and arthritis impact measures and the 6-min walk results have been reported elsewhere [4]. Although all 47 subjects in the intervention group completed pre- and post-testing with paired values for all three gait outcome measures and the walk test, posttest values for all measures were obtained for only 44 of the 45 subjects in the control group; one control subject did not have paired values for the walk test. Scores on the Arthritis Impact Measurement Scales (AIMS] Physical Activity Subscale and the AIMS Pain Subscale both declined (improved) for the intervention group. The differences were statistically significant (P = compared with the control group. The average distance walked in 6 min was similar between groups at baseline (F = 1.59, df = 1, P = 0.21). At the end of the study period, the intervention group demonstrated an average increase of 60 m from a baseline level of 390 m walked (P < ) 14). In contrast, the mean distance walked in 6 min for control subjects decreased by an average of 20 m from a baseline of 357 m. The inter-group differences in the 6-min walk were statistically significant (P < 0.001).

4 14 Peterson et al. Vol. 6, No. 1, March 1993 Stride Characteristic Outcome Measures Stride Length. Changes in stride length when the intervention group was compared with the control were statistically significant (free walking stride length, difference between groups: t = -2.7, df = 82, P = ; fast walking stride length, difference: t = -2.5, df = 6!j, P = 0.011, i.e., patients in the intervention group took longer steps as they walked at free and fast speeds. The free walking stride length of subjects in the intervention group increased an average of 0.1 m from an average baseline score of 1.1 m. The control subjects stride length decreased an average of 0.02 m from a baseline of 1.1 m. The fast walking stride length oi subjects in the intervention group increased an average of 0.2 m from an average baseline score of 1.2 KL. The control subjects stride length remained at baseline (an average of 1.2 m). Velocity. The inter-group differences for velocity were not statistically significant. Patients in the intervention group walked faster at both walking speeds (free walking velocity, difference between groups: t = -1.6, df = 89, P = 0.10; fast walking velocity, difference: t = -2.3, df = 89, P = 0.03). The free walking velocity of subjects in the intervention group increased an average of 5.6 m/min from an average baseline score of 55.6 m/min (n = 47, see Table 1). The control group vdocity increased an average of 2.1 m/min from a baseline of 51.4 m/min (n = 44). The fast walking velocity of subjects in the intervention group increased an average of 7.1 m/min from an average baseline score of 76.3 m/min, whereas fast velocity decreased by an average of 1.6 m/min from a baseline of 69.9 m/min for the control subjects. Cadence. Inter-group differences were not statistically significant. Patients in the intervention group took fewer steps per minute at both walking speeds (free walking cadence, difference between groups: t = 0.8; df = 89; P = 0.43; fast walking cadence, difference: t = 0.4; df = 89; P = 0.69). The free walking cadence of the subjects in the intervention group increased an average of 2.8 stepdmin from an average baseline sc:ore of 101 steps/min and cadence increased an average of 5.3 steps/min from a baseline of 95 stepdmin for the control subjects. The fast walking cadence of the subjects in the intervention group decreased 0.1 steps Irom an average baseline score of 122 stepdmin, and cadence increased by an average of 1.7 stepdmin from a baseline of 115 steps/min for the control subj ects. Changes in Pain and Gait Characteristics The baseline and poststudy walking distances positively correlate (r == 0.74, n = 91, P = ). For the controls, baseline distance walked correlates with poststudy distance walked (r = 0.84, P = ) and for the intervention group there is a similar correlation (r = 0.65, P = ). Because of the sample size, we shall not report the results for the unilateral-bilateral subgroups. Before and after measures of stride length, cadence, and velocity also show correlations of 0.5 or above. The distance walked at baseline correlated with the free and fast velocities, cadences, and stride lengths at baselme for both the controls and the intervention group. The poststudy distance walked also correlated with the free and fast velocities and stride lengths at baseline for both the controls and intervention group. Those who walked further at baseline, walked faster, tended to take longer strides, and took more steps. For the controls, an increase in the distance walked correlated inversely with an increase in the pain score (r = -0.33, n = 44, P = 0.03). However, after correction for multiple comparisons, this is not significant. Those who had decreased pain increased their walking distance. This was not true for the intervention group where there was no correlation between change in distance walked and change in pain (r = 0.05, n = 47, P = The change in distance walked for the intervention group correlated with a change in free cadence (r = 0.45, P = 0.002). For the controls, there was no correlation between the change in distance walked and the change in free cadence (r = 0.16, P = 0.3). The change in distance walked was independent of the baseline pain score for both the intervention group (r = -0.24, P = 0.1) and the control group (r = 0.2, P = 0 4 For all subjects, the change in pain correlated inversely with the pain score at baseline (r = -0.5, P = ). Those with a high pain score at the baseline tended lo have a decreased pain score at the end of the study. There were no statistically significant correlations for the controls between changes in pain score arid changes in gait characteristic. For the intervention group, there were no statistically significant correlations between changes in pain score and changes in gait characteristic. In general, the correlations are 0.5 and below. DISCUSSION Two studies have reported on the use of walking as an aerobic exercise for patients with arthritis [2,3]. The results of our study demonstrate that an intervention consisting of a supervised program of walking and education has a clinically, as well as statistically, significant impact on functional status (the 6-min walk test) andl stride length at free and fast walking speeds.

5 ~ ~ Arthritis Care and Research Gait in Osteoarthritis 15 A review of the literature has failed to reveal any other arthritis walking study that has used quantitative gait analysis. These results indicate that the method by which the patients increased their walking speed differed significantly at post-test. The 10% increase in the free walking velocity of patients exposed to the intervention was shown to be associated with a 3% increase in cadence and a 9% increase in stride length (P = ). In contrast, the 4% increase in the free velocity of the control group was associated with a 6% increase in cadence and a 9% decrease in stride length. At fast walking speed, the intervention group had a 9% increase in velocity, no increase in cadence, and a 1:7y0 increase in stride length. At fast walking speed, the control group had a 2% decrease in velocity, a 1% increase in cadence, and no increase in stride length. Thus, in the intervention group, increases in velocity were shown to be associated with increases in stride length rather than cadence at both free and fast walking speeds. In contrast, the subjects in the control group increased their velocity at the free walking speed by increasing their cadence and decreasing their stride length. These findings are clinically relevant. Gait improvement has been defined by increased velocity associated with gains in stride length rather than increases in cadence. This pattern was seen in our intervention group but not in the control group. Therefore, the intervention may have been effective in improving the gait pattern of patients exposed to the walking program. These patients did not walk faster by shuffling their feet more (i.e., increased cadence), they increased their speed by taking longer steps. Even though members of the intervention group demonstrated improvements in gait, their free and fast walking velocities remained below normal. Walters et al. "21 have reported that normal gait velocity in healthy seniior adults (n = 73; mean age = 68.2 years] was 73.6 m/min at free walking speeds and 89.5 m/min at fast walking speeds. At postintervention, our intervention group's measurements of walking velocity increased to 61.2 m/min at free walking speeds, and 83.4 m/min at fast walking speeds. As Murray et al. [13] have reported, people with knee pathology typically walk with lower walking speeds than normal controls possibly as a means to control joint pain. Baseline measurements of the walking velocity of subjects exposed to this intervention were higher than those reported in the study by Kroll et al. [lo]. Kroll's study population comprised people with either unilateral or bilateral knee OA (n = 18, average age = 68 years] who were measured preoperatively and postoperatively following total knee arthroplasty. In the present study, baseline measurements of velocity were 54.8 ~t 13.9 m/min at free walking speeds and 75.0 z 19.4 m/min at fast walking speeds for the intervention group. In contrast, the preoperative measurements of velocity reported by Kroll et al. were lower, 50.4 z 12.0 m/min at free walking speeds and 67.2 t '19.8 m/min at fast walking speeds. Although subjects in both studies had similar diagnoses, the patients in the current study exhibited fewer impairments in velocity at both walking speeds. These differences were not surprising because the patients in Kroll's population were candidates for total knee arthroplasty at the time of testing, whereas the patients in this study were not. The results from the quantitative stride analysis have helped to validate the improvements made in functional status as demonstrated by the 6-min test of walking distance. Liang and Jette [14] have pointed out that, because there is no one correct or preferred way to measure functional status of a person with chronic arthritis, current scales need to be compared with objective measures of the same functional activity. CONCLUSION In summary, the results reported show a strong and clinically significant impact of walking on stride characteristics of patients with OA of the knee without worsening pain. These results are consistent with the findings reported from previous studies that have demonstrated the aerobic benefits of walking in patient populations whose physical capacity has been significantly degraded by chronic joint disease. The increase in walking velocity due to the walking program was associated with an increase in stride length but not an increase in cadence, and thus meets the criteria for a true improvement in the patients' gait. We thank the patients and physicians who agreed to cooperati: in the study: Mark Kasper, MS, and Jeanne Cioppa-Mosca, PT. MBA, for assistance with collecting data; Louis L. Harris, MS, PT. Director of Rehabilitation at the Hospital for Special Surgery, and Sherry Backus, PT, of the Motion Analysis Laboratory for supportive assistance; and all our colleagues for their many helpful comments. This study was supported by NIH Multipurpose Arthritis Center Program Grant No. 1 P60 AR A1 and in part by a dissertation research grant to P.A. Kovar from the Arthritis Foundation. REFERENCES 1. Aloia JF, Cohn SH, Ostuni JA, Cane R, Ellis K: Prevention of involuntary bone loss by exercise. Ann Intern Med 89: , Minor MA, Ilewett JE, Webel RR, Anderson SK, Kay

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