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Physical activity and QoL among THA patients

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Title: Prospective study of physical activity and quality of life in Japanese women undergoing total

hip arthroplasty

Authors: Kimie Fujita, PhD１, Kiyoko Makimoto, PhD2, Riki Tanaka, MD１, Masaaki Mawatari,

MD１ and Takao Hotokebuchi, MD１

Affiliations:

１ Saga University, Department of Nursing, Faculty of Medicine, Saga, Japan,

2 Osaka University, Graduate School of Medicine, Osaka, Japan

Corresponding Author:

Kimie Fujita, PhD

Saga University, Department of Nursing, Faculty of Medicine

5-1-1 Nabeshima, Saga, 849-8501, Japan

E-mail: [email protected]

mailto:[email protected]


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Abstract

Background: Improvement in quality of life (QoL) in patients who went through total hip

arthroplasty (THA) is well studied, while the number of studies on improvement in actual daily

activity in THA patients is limited. The purpose of the study was 1) to describe the pre- to

post-operative changes in physical activity (PA) levels, 2) compared PA levels with healthy controls,

and 3) examine the association between PA levels and QoL in Japanese women undergoing THA.

Methods: PA was measured by pedometers, and QoL was assessed by the Short-Form-8, and the

Oxford Hip Scale questionnaires. Consecutive patients undergoing primary THA at Saga University

Hospital, Japan, in 2008 were eligible for the study. QoL and pedometers with accelerometers were

mailed to THA patients 1 month pre-THA, and 6 and 12 months post-THA. The control group

completed a single assessment of questionnaires and pedometers.

Results: Thirty-eight THA patients completed the study. Pre-operatively, the patient group had

significantly lower QoL scores than the comparison group. However, these differences disappeared

by 12 months post-THA. When improvement of PA function in THA patients was compared with

healthy controls, light PA was already 78% of the healthy controls at pre-THA period and improved

to 90% at 12 month. In contrast, moderate PA was 27% of the controls and rose to 77% by 12 months,

and vigorous PA remained low throughout the study period. PA was correlated with QoL scores.

Conclusion: The study shows relative recovery process of PA indicators in the THA patients and the

contribution of PA to the improvement of QoL.


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Introduction

Total hip arthroplasty (THA is a standard treatment for patients with advanced osteoarthritis (OA) ,

and many studies invariably have shown significant improvement in quality of life (QoL)

following THA[1-4]. Physical function is associated with improved Qol among older adults [5].

Physical function is also associated with health related QoL among people with arthritis [6]. In

contrast, recovery process of physical function in THA patients has been limited, and measurement

methods to evaluate the physical function vary among studies. Physical function in THA patients

were mostlyS measured by perceived physical functioning or functional capacity to perform

activities in non-home setting, and physical activity (PA) in patients’ home situation has rarely been

examined [7] Further, contribution of PA to the improvement in QoL has not been documented.

The most important physical function for THA patients is to perform actual daily activity

such as activities required at work, housekeeping, and leisure. Our qualitative study found that THA

patients became gradually able to resume housekeeping or to return to work as well as fulfill a social

role and they were able to carry out daily activities getting used to prosthesis [8]. PA levels are

commonly measured by self-administered questionnaire [8-10]. However, self-reported activity

levels may not accurately reflect objective measurement of physical activity. Assessment of the

reproducibility and relative validity of one physical activity scale (SQASH) showed only modest

overall test–retest reliability (r=0.58) and modest relative validity (r=0.45) compared with

accelerometer activity counts [10].

More objective measurements of PA levels among THA patients have been conducted using

pedometers [11-13]. The patients in these studies were assessed at a single time point, rather than

being followed prospectively, and the recovery of actual daily activity in the home situation in the

post-THA period has not been described to date. Additionally, QoL was not measured concurrently.

The purpose of this study was 1) to describe prospective changes (preoperative, 6 months and

12 months after THA) in PA levels, as objectively measured by accelerometer with pedometers


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(hereafter, pedometers), 2) to examine concurrent changes in QoL in Japanese women undergoing

and recovering from THA, 3) to compare these results with those of a healthy control group, and 4)

to assess the association between PA and QoL.

Materials and Methods

Patients

All consecutive patients, who were scheduled to undergo primary THA for OA in the Department of

Orthopedic Surgery at Saga University, between October and December (2008) were asked to

participate in the study. All the THAs were performed by the last author, and all the THA was

cementless. The study hospital had a well-established critical path, and patients are discharged on

average after 14 days of hospitalization. Inclusion criteria were 1) no disabilities in the lower limbs

other than the operated hip, 2) women, and 3) able to self-administer the questionnaire in Japanese.

Only women were asked to participate as over 80% of the patients at study site were women. For a

healthy comparison group, convenience sampling was used; graduate students’ parents and their

acquaintances were asked to participate in the study. Age-matching was used when recruiting control

subjects. Eligibility criteria for the healthy comparison group were those who were able to

ambulate without any difficulty. Body mass indexBMI) was not included in the eligibility criteria

because the prevalence of obesity is rare in Japanese.

Procedure

Patients on THA awaiting list were contacted by phone and asked to participate in the study about 4

weeks before THA. During the phone call the purpose of the research and research protocols were

explained to the participants. Questionnaires and pedometers (Lifecorder EX, Suzuken, Nagoya,

Japan) were mailed to the consenting patients at three times: 1 month before THA, and at 6 and 12

months after THA. Pedometers were used to measure the number of steps per day and PA levels. The


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demographic characteristics of the patients collected by self-administered questionnaires and medical

record before THA. Weight and height data for the study subjects and healthy controls were obtained

from self-administered questionnaire, and weight and height data from medical records for the study

subjects were also obtained.

To compare PA levels with a healthy comparison group, women matched for age in the Saga

Prefecture were asked to participate in the study. The comparison group was asked to fill out the

SF-8 once.

Ethical considerations

The study was approved by the ethics committee of Saga University School of Medicine.

Participants were informed that 1) study participation was voluntary, 2) study participation would not

affect treatment, 3) they could withdraw from the study at any point, and 4) only aggregated data

would be presented. Written informed consent was obtained from the patients, and individual study

results were mailed to the participants within 1 week returned pedometers.

PA level measurements

The pedometers measured the intensity of PA. Participants were asked by telephone, and a written

explanation with color pictures displaying how to wear pedometers were mailed to them. They were

requested wear the device from the time of waking to bedtime on a belt at waist level above the leg

for 10 consecutive days. Which side of the waist was not specified as a previous study found no

statistical differences in the number of steps of the pedometers attached to the both sides in 61 THA

patients [14]. Of these 10 days, data from the first two days and last one day were excluded from

analysis, leaving a total of 7 days of data for analysis. Lifelyzer basic software (Suzuken, Nagoya,

Japan) was used to analyze pedometer data, tabulating the number of steps and the intensity of PA as

expressed by the metabolic equivalent task (METs). Validity and reliability of Li fecorder has been


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described previously [15,16]. The PA levels were categorized into light (≤3 METs, e.g. walking at a

slow pace), moderate (3-6 METs, e.g. climbing stairs), and vigorous (≥6 METs, e.g., hiking), and the

duration (minutes per day) of each PA levels was tabulated. The patient group was assessed three

times (pre-THA, and 6 and 12 months post-THA), while the comparison group was assessed once.

Health-related QoL

Generic scale, the SF-8 was used to assess QoL. The SF-8 has eight subscales, and the summary

scores for physical (PCS) and mental (MCS) scores were tabulated in this study. The total score

ranges from 0 to 100, and higher scores indicate better QoL [17].

The Oxford Hip Score (OHS) is a scale used to measures QoL in patients with hip problems

[18]. The OHS consists of 12 items addressing physical functions and pain, and its total score ranges

from 12 to 48 (the higher the score, the lower the QoL). The previously validated Japanese version of

OHS (OHS-J) was used in this study [19].

Statistical analyses

Changes in the PA and QoL outcomes in the patient group across the three assessment times were

tested by one-way repeated-measures ANOVA (one group with three times), Non-paired t-tests with

Bonferroni correction were used to compare data between the THA group and the comparison group.

Effect sizes of the QoL outcomes were calculated to compare our study results with those of previous

studies [4]. Degree of relative recovery was examined to compare PA function of THA patients with

that of healthy controls by dividing the each PA indicator of THA patients by that of controls.

Spearman correlation coefficients were used to test the associations between PA level and QoL.

Results

Sixty-two patients were eligible and agreed to participate, and all of the patients completed the QoL


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scales and pedometer measurement during the pre-operative period. Of those, 20 dropped out at 6

months, while four additional patients declined to use the pedometer at 12 months (Figure 1). The

main reason for dropping out was the inconvenience of wearing a pedometer. In total, 38 patients

completed all the questionnaires and pedometer measurements. The age distribution of the study

completers and those who withdrew (hereafter, dropouts) did not differ significantly (60.9 and 61.5

years old, respectively; p>0.05). At pre-THA period, the mean number of steps and BMI did not

differ significantly between the completers and dropouts. The mean number of steps was 4,282 for

the completers and 4,632 for dropouts (p>0.05), while the mean BMI was 23.1 for completers and

23.0 for dropouts (p>0.05). In addition, the mean BMI based on self-reported data did differ

significantly from the mean BMI based on medical records (p>0.05). However, the OHS scores

differed significantly between the two groups; the mean was 29.9 for the completers and 34.9 for

dropouts (p=0.014).

The demographic characteristics of the patients and the control group are summarized in

Table 1. By design the mean age of the patients was similar to that of the healthy controls. The mean

BMI and prevalence of comorbidities was also similar in both groups (Table 1). Thirty-three patients

underwent unilateral THA, and one patient had a post-surgical complication of hip dislocation.

Insert Table 1 and Figure 1 here.

Improvements in QoL scores

The QoL of patients measured by SF-8 (MCS and PCS) and OHS improved significantly from the

pre-operative period to 12 months post-THA (Table 2). Of these four scales, the magnitude of

improvement was greatest for OHS. During the pre-operative period, the patient group had

significantly lower QoL scores than the control group. By 6 months, the patient group still had a

significantly lower SF-8 PCS score compared with the control group. At 12 months post-THA, all


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mean scale scores were similar between the patient and control groups (Table 2, Table3).

Insert Table 2,3 here.

Improvement in physical activity levels

The pedometer data showed that all the THA patients and healthy control wore the pedometer every

day. The mean hours of pedometer use per day was14.4 hours, ranging from10.6 hours to18.5 hours

per day during 7-day pedometer study period The number of steps improved significantly across the

three time points (Figure 2-1), and was accompanied by a significant increase in the moderate

intensity of PA (Figure 2-2). In terms of activity level, light and moderate PA improved significantly

at 1 year after THA, while no improvement was observed for vigorous PA (Table 4). When

improvement was measured by effect size, the largest effect was found in moderate PA between

pre-THA and 12 months post-THA, followed by moderate PA between pre-THA and 6 month post

THA (Table 4).

When PA was compared with that in the healthy control group, all PA level indicators for

THA patients were significantly lower pre-THA (Table 5). By 6 months post-surgery, with the

exception of light PA, the differences in all PA indicators between the patient and control groups

remained significant. By 12 months, only the duration of vigorous PA remained significantly

different between the two groups (Table 5).

Figure 3 shows relative improvement of PA function in THA patients. At pre-THA, light PA

was already 78% of the healthy controls and improved to 90% at 12 month. In contrast, moderate PA

was 27% of the controls and rose to 77% by 12 months, and vigorous PA remained low throughout

the study period (Figure 3).

Insert Table 4, 5 , Figure 3 here.


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Correlations between QoL and PA

During the pre-operative period, none of the PA indicators were correlated with the QoL scales (data

not shown). At 6 months after THA, the daily number of steps and PA intensity was weakly

correlated with SF-8 physical summary score and OHS scores (Table 6). Additionally, longer

duration of moderate and vigorous PA was significantly correlated with better QoL scores (with the

exception of a lack of correlation between the duration of vigorous PA and mental summary score).

By 12 months, most of the significant correlations between PA and QoL had disappeared.

Nevertheless, the amount of moderate PA remained significantly associated with SF-8 physical

summary and the OHS score, while vigorous PA remained associated with the OHS score (Table 6).

Insert Table 6

Discussion

To our knowledge, this prospective study is the first to report the post-operative improvement of PA

levels among THA patients as well as the association between PA level and QoL up to one year post

THA. Our study described the recovery process of PA levels in the first year after THA, and showed

continuous improvements in all the PA indicators except for vigorous PA throughout the year. By 1

year post-THA, most of the PA levels became 80 to 90% of those in the healthy comparison group.

Our study findings support previous study measuring relative recovery of physical function

in THA patients. Actual physical activity as measured with an activity monitor (AM) improved at 6

months after THA or TKA. However, this study showed small increase of PA because of the

followup may be too short still at 6 months, the AM device was not comfortable to wear.

Although pedometers have been used to measure actual daily activity in THA patients in


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previous studies [11, 13], data were collected at only a single time in these studies. Notably, the delay

between the operative procedure and the subsequent measurement of PA levels was ≥6 months in the

US study [11] and ≥10 years in an Ireland study [13].

Strength of our study is that prospective evaluation of the improvement the number of steps

and PA intensity, measurement of actual daily activity, from 6 months till 12 months after surgery.

This information on the recovery process will be useful for pre-operative orientation and patient

education. For example, specific information on daily activity can be given pre-operatively so that

patients can have realistic expectation for recovery.

Vigorous PA is not recommended for THA patients and, in this study, the vigorous PA level in

THA group was less than one-fourth of that of their healthy counterparts. Although increased PA

levels in THA patients are presumed to increase the risk of joint loosening, this concern is not

supported by the evidence. Indeed, a study by Dubs et al. [20] showed that THA patients who played

sports had a lower risk of joint loosening than those who did not. More recent evidence suggests that

patients’ PA levels were not associated with polyethylene wear [13]. Thus, multiple factors, other

than the PA level, seem to affect joint wear. As technology continues to advance in THA, monitoring

complication rates as well as PA levels is necessary to improve QoL in THA patients.

Preoperative demand has been shown to be a valid indicator of patient PA level post-THA

[21]. In this study, the authors classified patients’ expected PA level according to the Lahey Clinic

Demand Categories: 1) sedentary, 2) household ambulatory, 3) community ambulatory, 4) no

walking limit, and 5) sports/heavy work. They found that pre-operative demand, patient's age, weight,

bone stock, and health were predictors of post-THA activity. As patient activity varies greatly before

and after THA, pre-operative demand may require further refinement.

The significant improvement in health-related QoL noted in our patients is consistent with

that reported in earlier prospective studies [1-4]. Our study found that QoL scores tended to plateau

at 6 month post-THA, while PA levels continued to improve throughout to 12 months. This may


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reflect the ceiling effects of the QoL scales, and that an additional activity scale is necessary for

highly active patients [8].

Implication for clinical practice

While a number of studies have assessed the QoL of THA patients, PA levels have received much

less attention. In recent years, the number of younger patients receiving THA has been increasing,

and patients’ expectations for post-operative function will change accordingly.

To meet these increasingly varied expectations, pre-THA assessment is important to

understand each patient’s physical activity and expectation for postoperative activity. A pre-existing

scale could be used to measure changes in physical activities, including sport, work and leisure [9,

10].

Self-reported PA [8, 10] as well as objectively measured PA [11, 13] have shown great

variations before and after THA. Our study was limited to women; nevertheless, some of the women

engaged in vigorous PA, such as running. Although patient advice should be evidence-based,

evidence for the risk of loosening with increasing levels and intensity of PA is lacking for the new

generation of artificial joints [21, 22]. For now, the general guidelines remain useful for patient

education, but patients need to be informed about the uncertainty of risk associated with the new

technology.

Limitation of the study

Our sample size was small and patients were enrolled at one hospital in Japan. Thus, homogeneity of

the study sample may have resulted in less variation in the outcome compared with the other

pedometer studies [11, 13, 23]. However, the mean number of steps in our sample is comparable with

that in prior studies. Our sample was also limited to women because over 80% of the patients

attending the orthopedic department where this study was conducted were women. Men tend to be


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more active than women, and future studies need to include men with a variety of backgrounds.

Further, study dropouts had worse OHS scores than completers although PA indicators did not

differ significantly between these two groups. In the future study, larger sample is necessary to

examine the association between QoL and physical function.

Age-matching was used to recruit the healthy control group. However, they may have more

interest in PA and be more active than the average citizen, as the purpose of the study was to measure

PA level. A questionnaire survey of PA in the community may provide an unbiased estimate of

physical activity.

Seasonal variations in activity levels may have had some impact on the PA levels in the

study population. However, the study region has a moderate climate. As the pre-THA period was

conducted in winter, the 12 months follow-up also coincided with winter. Therefore, the

improvements in PA levels at 12 months post-THA were not affected by seasonal temperature

variations.

Conclusions

The current study examined changes in PA measured by a pedometer, as well as changes in QoL in

women undergoing THA. By 12 months after THA, the QoL scale scores in the patient group

became comparable with those of the healthy control group. Other than one exception, all physical

activity indicators in the patient group improved significantly over time and reached 80 to 90% of

those in the control group at 12 months after THA.

Conflict of interest

The authors have no conflicts of interest to declare with respect to employment, consultancies, stock

ownership, honoraria, paid expert testimony, patent applications/registrations, and research grants or

other funding.


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Table 1. Characteristics of the patients prior to THA and the control subjects

THA Controls p-value*

n=38 (%) n=38 (%)

Age (years) Mean ± SD 60.9±9.1 61.5±10.9 ns Range 43–82 41–83

BMI (kg/m2) Mean ± SD 23.0±3.6 23.0±3.2 ns

Range 17.8–32.5 17.0–33.8

Living arrangement

Living with a family member 33 86.8 33 86.8 ns

Living alone 5 13.2 5 13.2

Employment

Yes 5 13.2 13 34.2 0.032

No 33 86.8 25 65.8

Comorbidities

Yes 23 60.5 25 65.8 ns Hypertension 11 28.9 13 34.2

Dyslipidemia 6 15.8 10 26.3

Diabetes mellitus 3 7.9 4 10.5

THA

Unilateral 33 86.8

Bilateral 5 13.2

Complication

Yes 1 2.6

Hip dislocation 1 2.6

Note: *t-test


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Pre vs.6 M

6 Mvs. 12

M

Prevs. 12

M

SF-8 Physical CS <0.001 NS <0.001 –1.13 –0.24 –1.32Mental CS <0.001 NS <0.001 –0.66 –0.14 –0.78

OHS <0.001 <0.001 <0.001 1.86 0.47 2.33

Table 3. Changes in the mean scores of SF-8 from pre operation to 12 month after THA, and control

Pre vs.Con

6 Mvs.Con

12 Mvs.Con

SF-8 Physical CS <0.001 NS NS –1.43 –0.38 -0.14

Mental CS 0.02 NS NS –0.55 0.12 0.37

Abbreviations: M = month; SF-8 = short form 8; OHS = Oxford hip score; CS = component summary score.

6 M post-THA 12 M post-THA p-value

Mean ± SD Mean ± SD

47.85 ± 4.72 48.99 ± 4.5152.89 ± 5.25 53.63 ± 3.67

19 ± 5.86 16.2 ± 4.48

p-value Control group12 M post-THA p-valueEffect size

48.99 ± 4.51

Table 2. Changes in the mean scores of SF-8,OHS from pre operation to 12 month after THA

Pre-THA6 M post-

THA12 M post-

THAEffect size

48.88 ± 6.11 52.89 ± 5.25 53.63 ± 3.67

Mean ± SD Mean ± SD Mean ± SD

41.13 ± 5.96 47.85 ± 4.72

Pre-THA

29.9 ± 5.89 19 ± 5.86 16.2 ± 4.48

Mean ± SDMean ± SD

49.63 ± 5.3148.99 ± 4.51

Pre-THA

Mean ± SD

41.13 ± 5.96

48.88 ± 6.11

p-value Control group

Mean ± SD

49.63 ± 5.31

52.27 ± 6.19

Control group

Mean ± SD

49.63 ± 5.31

52.27 ± 6.19

6 M post-THA

Mean ± SD

47.85 ± 4.72

52.89 ± 5.25

p-value

Mean ± SD

41.13 ± 5.9648.88 ± 6.1129.9 ± 5.89

p-value

52.27 ± 6.1953.63 ± 3.67


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Table 4. Number of steps and mean level of physical activity per day for THA patients

Pre-THA 6 M post-THA p-value 6 M post-THA 12 M post-THA p-value Pre-THA 12 M post-THA p-value

Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SDPre vs. 6

M6 M vs. 12

MPre vs. 12

MNo. of steps (steps/day) 4632 ± 2246 5657 ± 2106 0.001 5657 ± 2106 6163 ± 2410 0.017 4632 ± 2246 6163 ± 2410 <0.001 –0.45 –0.24 –0.68Light PA# (minutes/day) 107 ± 49 123 ± 42 0.007 123 ± 42 125 ± 42 NS 107 ± 49 125 ± 42 0.005 –0.33 –0.04 –0.36Moderate PA(minutes/day) 16 ± 18 32 ± 49 0.04 32 ± 49 46 ± 50 0.001 16 ± 18 46 ± 50 <0.001 –0.87 –0.28 –1.63Vigorous PA(minutes/day) 1 ± 3 1 ± 5 NS 1 ± 5 3 ± 4 NS 1 ± 3 3 ± 4 NS –0.02 –0.2 –0.37PA:physical activity*One-way repeated-measures ANOVA with Bonferroni p-value correction for multiple comparisons, and two-way repeated-measures ANOVA for two age groups

Table 5. Number of steps and mean level of physical activity per day for THA patients and healthy personsPre-THA p-value 6 M post-THA p-value 12 M post-THA p-value

Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SD Mean ± SDPre vs.

Con6 M vs.

Con12 M vs.

ConNo. of steps ( steps/day) 4632 ± 2246 7228 ± 3132 <0.0015657 ± 2106 7228 ± 3132 0.012 6163 ± 2410 7228 ± 3132NS –1.16 –0.75 –0.44Light PA# (minutes/day) 107 ± 49 137 ± 55 0.016 123 ± 42 137 ± 55 NS 125 ± 42 137 ± 55 NS –0.6 –0.32 –0.28Moderate PA(minutes/day) 16 ± 18 60 ± 42 <0.001 32 ± 49 60 ± 42 0.01 46 ± 50 60 ± 42 NS –2.4 –0.57 –0.28Vigorous PA(minutes/day) 1 ± 3 12 ± 19 0.001 1 ± 5 12 ± 19 0.001 3 ± 4 12 ± 19 0.003 –3.8 –2.16 –2.25

Effect size

Effect sizeControl Control Control


20

Table 6. Spearman's correlations between the SF-8, OHS and physical activity 6 months and 12 month after THA

Duration of physical activity according to

intensity level

Month Step Light PA Moderate PA Vigorous PA

SF-8

Mental CS 0.090 0.009 0.347** 0.176 6 M Physical CS 0.344* 0.045 0.525** 0.432* OHS –0.325* –0.028 –0.647** –0.474*

SF-8

Mental CS 0.107 0.041 0.215 0.136 12 M Physical CS 0.186 0.032 0.321* 0.266 OHS –0.218 0.007 –0.481** –0.389* **p<0.01, *p<0.05


21

　　　　

6 months

12 months

Fig 1. Patient disposition

Complete data for all three times (38 women)

Pre-operative data (n=62)

Dropouts (20)・Refused to use the pedometer (20)

Dropouts (4)・Refused to use the pedometer (4)


22

全体歩数

Note. One-way repeated-measures ANOVA with Bonferroni p-value correction for multiple comparisons, and two-way repeated-measures ANOVA for two age groups

Fig. 2-2. Improvement in the PA in THA patients from pre-THA to 6and 12 months post-THA with the control group as a reference

Fig. 2-1. Improvement in the number of steps in THA patients from pre-THA to 6and 12 months post-THA with the control group as a reference

Minutes/daysteps/day

0.004

0.000

0.050

0.012

0.000

p<0.001

P=0.010

P<0.001

P=0.040 P=0.001

Pre-THA 6 M post-THA 12 M post-THA ControｌPre-THA 6 M post-THA 12 M post-THA Controｌ

Moderate physical activitySteps


23

Figure 3 Degree of relative recovery for PA indicators compared with healthy controls

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Pre-THA 6M post-THA12 M post-THA

Per

cen

tage

of c

ontr

ols'

PA

fu

nct

ion

No. of steps

Light PA

Moderate PA

Vigorous PA

revision activity for tha

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