Physical Therapy Assisgment

 Assignment: Write a 300-word minimum clinical application summary of the research article or
case study report.
Due Dates: Students needs to turn in a copy of their research article or case study report for

approval no later than Tuesday 06/01/21 via google classrooms.
The Final assignment is DUE ON July 01, 2021.

Instructions:
The paper should be 300-word minimum, typed, double spaced, Times New Roman 12 font, 1”
margin.
Write the paper in the following order:
I. Citation: AMA style MUST BE USED
II. Clinical Application:
a. Describe why was the research/case study done (what is the purpose)
b. Describe any and all test and measurements used in the research/case
study
c. Select and describe the interventions that are appropriate for the scenario
d. Describe what you would check to assure patient safety during the
intervention
e. Describe a condition under which you would need to stop the intervention
f. Describe a condition under which you would contact the physical therapist
for additional instruction

Example: Use the following format.
I. Citation in AMA syle.

Physical Functioning Before and After Total Hip Arthroplasty: Perception and Performance Inge van den Akker-Scheek, Wiebren Zijlstra, Johan W Groothoff, Sjoerd K Bulstra, Martin Stevens

Background and Purpose. Self-report and performance-based measures of physical functioning in people before and after total hip arthroplasty seem to present different information. The relationship between these different measures is not well understood, and little information is available about changes in this relationship over time. The aims of this study were: (1) to determine the relationship between self-report and performance-based measures of physical functioning before and after total hip arthroplasty, (2) to assess the influence of pain on the relationship, and (3) to determine whether the relationship changes over time.

Subjects and Methods. Seventy-five subjects admitted for total hip arthro- plasty were included and examined before and 6 and 26 weeks after surgery. The relationships between the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical functioning subscale and walking speed and gait variability were examined by use of generalized estimating equations, which included interac- tions with time and the WOMAC pain subscale.

Results. The relationship between self-report and performance-based measures of physical functioning was poor. Pain appeared to have a considerable influence on self-reported physical functioning. The relationship did not appear to change over time.

Discussion and Conclusion. The influence of pain on self-reported physical functioning serves as an explanation for the poor relationship between self-reported and performance-based physical functioning. When using a self-report measure such as the WOMAC, one should realize that it does not seem to assess the separate constructs—physical functioning and pain—that are claimed to be measured.

I van den Akker-Scheek, PhD, is Human Movement Scientist and Epidemiologist, Department of Orthopedics, University Medical Center Groningen, University of Groningen, PO Box 30001, 9700 RB Groningen, the Netherlands. Address all correspondence to Dr van den Akker-Scheek at: i.scheek@orth.umcg.nl.

W Zijlstra, PhD, is Human Move- ment Scientist, Center for Human Movement Sciences, University Medical Center Groningen, Uni- versity of Groningen.

JW Groothoff, PhD, is Professor of Work and Health, Department of Health Sciences, University Medi- cal Center Groningen, University of Groningen.

SK Bulstra, MD, PhD, is Orthope- dic Surgeon, Professor of Ortho- pedics, and Head of Department, Department of Orthopedics, Uni- versity Medical Center Groningen, University of Groningen.

M Stevens, PhD, is Research Co- ordinator and Human Movement Scientist, Department of Ortho- pedics, University Medical Cen- ter Groningen, University of Groningen.

[van den Akker-Scheek I, Zijlstra W, Groothoff JW, et al. Physical functioning before and after total hip arthroplasty: perception and performance. Phys Ther. 2008;88: 712–719.]

© 2008 American Physical Therapy Association

Research Report

Post a Rapid Response or find The Bottom Line: www.ptjournal.org

712 f Physical Therapy Volume 88 Number 6 June 2008

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

Outcomes after total hip arth-roplasty can be assessed bymeans of self-report mea- sures; the Western Ontario and Mc- Master Universities Osteoarthritis In- dex (WOMAC) is a disease-specific questionnaire and is one of the most widely used and recommended measures.1,2 The questionnaire is completed by the patient; the score provides an indication of the pa- tient’s physical functioning, stiffness, and pain. Besides self-report mea- sures, performance-based measures, in which the patient actually has to perform one or more activities of daily living, are available. Advantages and disadvantages have been re- ported for both kinds of measures.3,4

The advantages of self-report mea- sures are that they are easy to ad- minister, are inexpensive, and can evaluate multiple aspects of func- tion in one test. Mentioned disad- vantages are that self-report mea- sures are influenced by expectations and beliefs of the patients and by impaired cognition and errors in memory; performance-based instru- ments do not have these disadvan- tages. However, the disadvantage of performance-based instruments is that activities often have to be as- sessed in an artificial laboratory en- vironment, a task that can be time- consuming and expensive. With the introduction of ambulation measur- ing devices that use body-fixed sen- sors, physical functioning can be as- sessed objectively without these disadvantages.5 Spatiotemporal gait parameters, such as walking speed, can be accurately determined, and step-to-step variability as a measure of gait efficiency can be calculated from the obtained measurements.

Research into the relationship be- tween self-report and performance- based measures has shown a poor to moderate relationship between these 2 types of measures.3,6,7 Each measure seems to assess different aspects of recovery. It is recom-

mended, therefore, that both mea- sures be used to obtain full insight into outcomes after total hip arthro- plasty because these measures are considered to be complementary.3,8

However, research into the possible explanations for the poor to moder- ate relationship is scarce. Recently, Terwee et al9 investigated the influ- ence of pain on the relationship be- tween self-report and performance- based outcome measures before and after total knee arthroplasty. They discovered that self-report measures of physical functioning are influenced by pain more than are performance- based measures, a finding that could explain the low correlation between them. It is our hypothesis that this ex- planation also is valid for total hip arthroplasty.

Additionally, most research determin- ing the relationship between self- report and performance-based mea- sures is limited to measurement at one point in time (eg, before surgery or 12 months after surgery). Therefore, in- formation about whether the relation- ship between these 2 types of mea- sures changes over time is scarce. Research is needed on the relationship between self-report and performance- based measures in people before total hip arthroplasty as well as across the spectrum of recovery after surgery.3,10

Research on total knee arthroplasty demonstrated that the correlations be- tween the self-report and performance- based measure scores changed over time after surgery; the correlations were somewhat better 3, 6, and 12 months after surgery than they were before surgery.9 This change in cor- relations over time can be explained by the influence of reduced pain. Be- fore surgery, patients are in pain, which is hypothesized to influence the self-report measure; because of the pain, patients value their physi- cal functioning less than is actually the case. There is an expectation that pain will decrease markedly shortly after surgery, and it is hy-

pothesized that this sudden change will influence self-reported physical functioning: Patients overrate their physical functioning compared with what the performance-based mea- sure shows because they suddenly do not perceive any pain while exe- cuting the activities. Over the long term after surgery, better concor- dance between self-reported and performance-based physical func- tioning is expected because patients do not perceive pain over time and, therefore, can provide a more accu- rate evaluation of their physical func- tioning. We hypothesize, therefore, that in patients with total hip arthro- plasty, the relationship between self- report and performance-based out- come measures will change over time, as will the influence of pain.

The aims of this study were: (1) to determine the relationship between self-report and performance-based measures of physical functioning after total hip arthroplasty, (2) to assess the influence of pain on the relationship, and (3) to determine whether the relationship changes over time. In this study, the WOMAC physical functioning sub- scale (WOMAC-PF) was used as the self-report outcome measure and walking speed and step-to-step vari- ability were used as the performance- based outcome measures in people before total hip arthroplasty and over the short term and long term after surgery.

Method Subjects People admitted to a medical center orthopedic department for unilateral total hip arthroplasty and participat- ing in the short-stay program be- tween September 2002 and August 2004 were included in the study. The criteria for the short-stay pro- gram were as follows: estimated sur- gery time of less than 120 minutes, weight of less than 110 kg, estimated hospital stay of less than 6 days, no

Hip Arthroplasty and Physical Functioning

June 2008 Volume 88 Number 6 Physical Therapy f 713

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

signs of severe mobility disablement or psychological dysfunction, and no severe deformity of the spine. Study participants were allowed to start walking with aids on the first day after surgery and were discharged on day 5 after surgery unless there were complications.

In total, 87 people were admitted for total hip arthroplasty during the study period. All were willing to par- ticipate in the study. Measurements were performed at the time of admis- sion and 6 and 26 weeks after the surgery, when the study participants visited the outpatient clinic. The par- ticipants were asked to complete the WOMAC, and gait analysis was per- formed. Data on participant charac- teristics such as sex, age, and body mass index (BMI) were gathered at admission.

Of the 87 people willing to partici- pate in the study, 12 were excluded from further analyses because they did not complete the questionnaire or the gait analysis at all 3 measure- ment times for various reasons: 1 had severe surgical complications, 1 moved out of the country, 1 died, 2 had health problems attributable to causes unrelated to the orthopedic surgery, 2 refused further participa- tion because of personal circum- stances, 4 did not visit the outpatient clinic, and 1 had a total hip arthro- plasty on the contralateral side. The remaining 75 participants were pre- dominantly women (n�53, 70.7%), with a mean age of 62.7 years (SD�11.7) and a mean BMI of 26.6 kg�m�2 (SD�3.4). The mean length of the hospital stay was 7.0 days (SD�3.3).

Measures The Dutch version of the WOMAC was used; it has been proven valid and reliable for people before and after total hip arthroplasty.11,12 The WOMAC is a disease-specific, self- report outcome measure for people

before and after hip arthroplasty and consists of the subscales physical functioning, stiffness, and pain. Two of the subscales, the WOMAC-PF (17 items) and the WOMAC pain sub- scale (WOMAC-P) (5 items), were used in this study. Responses were given on a 5-point Likert scale. Scores from both subscales were re- coded into a 100-point scale, with a higher score representing better physical functioning or less pain.

Gait analysis was performed with the DynaPort System.* This is an am- bulation system consisting of a data recorder (dimensions�125�95�34 mm; weight�295 g) that is attached to an individual’s lower back with a neoprene belt around the waist, over the individual’s clothes. The data recorder contains 3 uniaxial, piezoelectricity-resistive accelerome- ters that measure acceleration in the frontal, sagittal, and transverse planes and a memory card on which data are stored. Three penlight batteries are attached to the belt. In this study, participants were asked to walk 20 m at their preferred speed in a hospital corridor. After each mea- surement, the data were transferred from the memory card to a personal computer and displayed graphically. The beginning and end of each test part were marked manually in the DynaPort software. Analysis of the accelerometer signals and extraction of data for the gait parameters were performed by McRoberts BV.* Sev- eral movement features can be deter- mined from the accelerometer sig- nals.13–15 Only the parameters of walking speed and step-to-step vari- ability were used in this study as measures of gait steadiness because they reliably reflect changes in an individual’s gait efficiency.16 Step-to- step variability is expressed as the coefficient of variation (CV), as fol- lows: (SD of step duration/mean

step duration)�100. The ambulation method is used to determine spatio- temporal gait parameters from lower-trunk accelerations. In previ- ous studies,13–15 this method was proven to be a valid means for deter- mining gait parameters.

Data Analysis Descriptive statistics (mean and SD) were used to describe participant characteristics, scores on the WOMAC-PF and the WOMAC-P, pre- ferred walking speed, and step-to- step variability (expressed as the CV) at the 3 measurement times (before surgery and 6 weeks and 6 months after surgery). General linear model repeated-measures analyses were used to determine whether the scores changed over time. General linear model repeated-contrast anal- yses were used to determine whether the scores changed between the measurements obtained before sur- gery and over the short term after surgery or between the measure- ments obtained over the short term and over the long term after surgery, or both. Pearson correlation coeffi- cients were calculated for the scores obtained before surgery (Tab. 1).

The relationship between the WOMAC-PF and preferred walking speed was assessed by applying gen- eralized estimating equations (GEEs) to longitudinal data to account for correlations between repeated ob- servations for each subject. First, a “naive” linear regression analysis is carried out, and regression coeffi- cients are estimated, assuming that the repeated observations within one subject are independent.17 Be- cause this is not the case, a correc- tion must be made for these within- subject correlations. This is done by adding to the regression model a cor- relation matrix that consists of an estimation of the correlations be- tween the different time points within a subject. In this study, an exchangeable correlation structure

* McRoberts BV, Raamweg 43, 2596 HN, The Hague, the Netherlands.

Hip Arthroplasty and Physical Functioning

714 f Physical Therapy Volume 88 Number 6 June 2008

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

was used, assuming all correlations to be the same. The regression coef- ficients are then reestimated, with correction for the dependency of the observations. Through standardiza- tion of the regression coefficients [(regression coefficient�SDx)/SDy], the coefficients can be interpreted as correlation coefficients.

In the first GEE model, the WOMAC- PF score was included as a depen- dent variable and preferred walking speed was included as an indepen- dent variable. In the second model, the WOMAC-P score was added. Ad- ditionally, a walking speed�time in- teraction and a pain�time interac- tion were included (models 3 and 4). The participant characteristics of sex, age, and BMI were included as potential confounders (model 5). The regression coefficients were standardized. The complete analysis was repeated with the CV [(SD of step duration/mean step dura- tion)�100] instead of preferred walking speed as an independent variable.

The Statistical Package for the Social Sciences, version 14.0,† and STATA,

version 9.1,‡ were used for data anal- ysis. A P value of less than .05 was considered statistically significant.

Results The mean WOMAC-PF and WOMAC- P scores, preferred walking speed, and CV at the 3 assessment times are shown in Table 2. For all variables, a significant improvement was seen over the 3 measurement times (over- all time effect; P�.001). For the WOMAC-PF, a significant improve- ment was seen between each of the 3 measurement times. The overall significant improvement seen for

the WOMAC-P and CV was attribut- able to a significant improvement be- tween the measurements before sur- gery and over the short term after surgery. For walking speed, the over- all significant improvement was at- tributable to a significant improve- ment between the 2 measurements after surgery.

The results of the GEE analysis with WOMAC-PF as the dependent vari- able and preferred walking speed as the independent variable are shown in Table 3. In model 1, the standard- ized regression coefficient of pre- ferred walking speed was .40; adding WOMAC-P to the regression model

† SPSS Inc, 233 S Wacker Dr, Chicago, IL 60606.

‡ StataCorp LP, 4905 Lakeway Dr, College Sta- tion, TX 77845.

Table 1. Pearson Correlation Coefficients for the Measures Before Surgerya

Measure Correlation With:

WOMAC-PF PWS CV WOMAC-P

WOMAC-PF 1.00

PWS .13 1.00

CV .13 �.28b 1.00

WOMAC-P .68c �.07 .30b 1.00

a WOMAC�Western Ontario and McMaster Universities Osteoarthritis Index, PF�physical functioning subscale of the WOMAC, PWS�preferred walking speed, CV�coefficient of variation, P�pain subscale of the WOMAC. b P�.05. c P�.01.

Table 2. Mean (SD) of the Self-report and Performance-based Outcome Measures and Pain at the 3 Measurement Times and Results of the General Linear Model Repeated-Measures Analysisa

Measure X (SD) P for: Partial eta Squared

Before Surgery

Short Term After Surgery

Long Term After Surgery

Overall Time Effect

Before Surgery vs Short Term After Surgery

Short Term After Surgery vs Long Term After Surgery

WOMAC-PF score

46.9 (16.5) 72.8 (17.2) 78.4 (14.9) <.001 <.001 .002 .65

PWS (m/s)b 0.93 (0.20) 0.94 (0.19) 1.12 (0.20) <.001 .602 <.001 .44

CV (%)b 12.4 (6.1) 10.1 (3.6) 9.9 (3.2) .001 .007 .267 .11

WOMAC-P score

50.4 (19.0) 84.1 (14.4) 84.9 (16.7) <.001 <.001 .707 .67

a Preferred walking speed (PWS) and coefficient of variation (CV) before surgery were calculated for 69 participants because 6 measurements were missing as a result of technical problems. Significant values are shown in boldface type. WOMAC�Western Ontario and McMaster Universities Osteoarthritis Index, PF�physical functioning subscale of the WOMAC, P�pain subscale of the WOMAC. b Normative data (n�19, comparable characteristics)5: PWS�1.32 m/s (SD�0.15 m/s), CV�8.1% (SD�3.2%).

Hip Arthroplasty and Physical Functioning

June 2008 Volume 88 Number 6 Physical Therapy f 715

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

resulted in a decrease to .22 (model 2). Neither the interaction term pre- ferred walking speed�time (model 3) nor the interaction term WOMAC- P�time (model 4) was significant; this result implies that the contribu- tions of preferred walking speed and pain to the regression model do not

change over time. On the basis of the fact that the regression coefficient of PWS showed only a minimal change when the participant characteristics of sex, age, and BMI were added to the regression model (.21 versus .22), these characteristics are not

considered to be confounders (model 5).

Table 4 shows the results of the GEE analysis with WOMAC-PF as the de- pendent variable and CV as the inde- pendent variable. In model 1, the standardized regression coefficient

Table 3. Results of the Generalized Estimating Equation (GEE) Analysis With Physical Functioninga as the Dependent Variable and Preferred Walking Speed (PWS) as the Independent Variableb

GEE Model Independent Variable

Standardized Regression Coefficient (95% Confidence Interval)

1. PWS PWS .40 (.29 to .51)

2. PWS�WOMAC-P PWS .22 (.14 to .29)

WOMAC-P .77 (.69 to .85)

3. PWS�WOMAC-P �Time�PWS� time interaction

PWS .16 (�.01 to .32)

WOMAC-P .66 (.55 to .77)

Interaction NS

4. PWS�WOMAC-P �Time�WOMAC-P �time interaction

PWS .19 (.10 to .29)

WOMAC-P .66 (.49 to .83)

Interaction NS

5. PWS�WOMAC-P �Participant characteristics (BMI, age, sex)

PWS .21 (.12 to .30)

WOMAC-P .77 (.69 to .85)

a From the physical functioning subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). b P�WOMAC pain subscale score, NS�not significant, BMI�body mass index.

Table 4. Results of the Generalized Estimating Equation (GEE) Analysis With Physical Functioninga as the Dependent Variable and Coefficient of Variation (CV) as the Independent Variableb

GEE Model Independent Variable

Standardized Regression Coefficient (95% Confidence Interval)

1. CV CV �.14 (�.26 to �.03)

2. CV�WOMAC-P CV �.11 (�.18 to �.03)

WOMAC-P .82 (.74 to .89)

3. CV�WOMAC-P �Time�CV� time interaction

CV �.07 (�.16 to .02)

WOMAC-P .70 (.59 to .80)

Interaction NS

4. CV�WOMAC-P �Time�WOMAC-P �time interaction

CV �.08 (�.16 to .00)

WOMAC-P .68 (.52 to .85)

Interaction NS

5. CV�WOMAC-P �Participant characteristics (BMI, age, sex)

CV �.09 (�.17 to �.01)

WOMAC-P .82 (.74 to .89)

a From the physical functioning subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). b P�WOMAC pain subscale score, NS�not significant, BMI�body mass index.

Hip Arthroplasty and Physical Functioning

716 f Physical Therapy Volume 88 Number 6 June 2008

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

of CV was �.14; adding WOMAC-P to the regression model resulted in a decrease to �.11, but there was an overlap of the 95% confidence inter- vals (model 2). As in the models with PWS as the independent variable, neither the interaction term CV� time (model 3) nor the interaction term WOMAC-P�time (model 4) was significant. The regression coef- ficient of CV showed only a minimal change when the participant charac- teristics of sex, age, and BMI were added to the regression model (�.11 versus �.09); therefore, these char- acteristics are not considered to be confounders (model 5).

Discussion The aims of the present study were to determine the relationship be- tween self-report (WOMAC-PF) and performance-based (walking speed and step-to-step variability) out- come measures of physical function- ing in people with total hip arthro- plasty, to assess the influence of pain on the relationship, and to de- termine whether the relationship changes over time.

Pain and a deterioration in physical functioning are the primary reasons for a total hip arthroplasty. In the early period after surgery, pain is re- duced, although physical function- ing may be diminished compared with that before surgery because pa- tients have just undergone surgery and usually walk with crutches in the first few weeks after surgery.16

However, the measurements that we obtained in the short term after surgery already indicated an im- provement in the self-reported phys- ical functioning outcome measure (WOMAC-PF). The performance- based measure CV also showed an improvement, but this value could be distorted by the use of crutches by most of the participants at this measurement time. The performance- based measure preferred walking speed, however, did not show an

improvement at the 6-week measure- ment time over the value obtained before surgery. This difference in outcomes between a self-report mea- sure and a performance-based mea- sure of the same construct (physical functioning) is consistent with the findings of other investigators.9,18 –20

These observations indicate a poor relationship between self-report and performance-based physical func- tioning measures.

The results of the GEE analyses per- formed on our results confirmed that conclusion: The regression coefficient in the model containing WOMAC-PF as a dependent variable and preferred walking speed as an independent vari- able, both measured 3 times, was only .40, and the regression coefficient in the model containing CV as an independent variable was even lower (�.14). The poorer relationship be- tween CV and the WOMAC than be- tween walking speed and the WOMAC was also found by Lindemann et al.16

Our findings are thus in accordance with our hypothesis of a poor rela- tionship between self-report and performance-based measures of phys- ical functioning. Determining the rela- tionship with multiple assessments over time, with correction for the de- pendency of longitudinal data as we applied in our analyses, did not result in adverse findings compared with those of other investigators using cor- relation coefficients.

In order to examine the second aim of our study—to determine the influ- ence of pain on the relationship— WOMAC-P was added to the models containing the self-report measure as a dependent variable and the performance-based measure as an in- dependent variable. This method re- sulted in an even lower regression coefficient for preferred walking speed, whereas pain made a great contribution (.77). For the other performance-based measure, CV, the influence of pain was less pro-

found; the regression coefficient for CV was slightly lower, but there was an overlap of the 95% confidence intervals. However, for pain there was an equally high regression coef- ficient (.82) in the model containing CV as an independent variable and in the model containing preferred walking speed as an independent variable. Adding participant charac- teristics (age, sex, and BMI) did not change the relationship between the self-report and performance-based measures. The WOMAC-P and the WOMAC-PF appeared to be closely linked. With the WOMAC-PF, pain— or diminishing pain after surgery— also is measured when the aim is to assess solely physical functioning. People seem to be unable to sepa- rate pain and physical functioning when pain is present or when a change in pain has occurred. Through differentiation with 3 subscales, the WOMAC is claimed to measure dif- ferent constructs. However, our re- sults and those of other investiga- tors9,20 question the factorial validity of the WOMAC-PF.

The fact that pain was determined with the same questionnaires as those used to assess self-reported physical functioning can be consid- ered a limitation of the present study. Because the present study was part of a larger study,21 we also had access to data from the Medical Out- comes Study 36-Item Health Survey Questionnaire (SF-36). We chose to initially use the WOMAC-P because the WOMAC is a disease-specific questionnaire and the SF-36 is a ge- neric quality-of-life questionnaire. The WOMAC asks about difficulties with specific activities that are prob- lematic for people with arthritis, whereas the SF-36 assesses overall health. Moreover, the WOMAC has been found to be more responsive than the SF-36.18,22 However, when the SF-36 pain subscale was used in- stead of the WOMAC-P, the regres- sion coefficient was somewhat

Hip Arthroplasty and Physical Functioning

June 2008 Volume 88 Number 6 Physical Therapy f 717

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

lower, albeit still high (preferred walking scale model: .77 with WOMAC-P and .64 with SF-36 pain subscale; CV model: .82 with WOMAC- P and .70 with SF-36 pain subscale). This finding strengthens our conclu- sion that pain has a significant influ- ence on the self-report physical func- tioning outcome measure.

The third aim of the present study was to determine whether the rela- tionship between self-report and performance-based outcome mea- sures changes over time. On the ba- sis of the observation that the WOMAC-PF scores and the walking speed values developed in different directions over time, we hypothe- sized that the relationship between them would change over time. The interaction term was not significant; this finding implies that the associa- tion did not change over time (Tab. 3). Even when pain was not included in the regression model, the interac- tion term was not significant (data not shown). In the model with CV as an independent variable, the interac- tion term was not significant either (Tab. 4). Lindemann et al16 found similar results; they performed a gait analysis and assessed the WOMAC in people before and after total hip ar- throplasty and did not find changes in correlation coefficients after sur- gery compared with before surgery. Unfortunately, their study had the limitation of a small study group (N�17) and only one measurement after surgery (3 months after surgery). Other investigators did find a chang- ing association. Terwee et al9 found changes in correlation coefficients over time between the DynaPort System knee score (performance- based functioning score) and the WOMAC for people before and af- ter total knee arthroplasty. However, all mentioned studies used correla- tion coefficients to describe the as- sociation between self-reported and performance-based physical function- ing. This method neglects the fact

that the observations are repeated measures. With a longitudinal design like that used in the present study, a correction is made for the depen- dency of the data. Additionally, con- founding and effect modification can be studied, resulting in a more in- depth analysis. Furthermore, in the present study, the sample size was considerable and measurements were obtained over the short term and long term after surgery, as sug- gested by Lindemann et al.16

Finally, we analyzed whether the in- fluence of pain changed over time. From the results, it appeared that pain had a strong, consistent influ- ence on self-reported physical func- tioning. However, the influence of pain did not change over time, even when pain levels were lower. There- fore, even low levels of pain have the potential to influence self-reported physical functioning, a conclusion counter to what was hypothesized and opposite to traditional thinking. It is not known what the influence of a total absence of pain is; people were not totally pain-free at 6 months (mean WOMAC-P score of 84.9 out of 100) (Tab. 2). This aspect should be the object of further re- search in which people are addition- ally assessed at 12 months or later.

A remark is needed regarding the fact that preferred walking speed and CV were used as performance- based measures of physical function- ing. There is no gold standard for the measurement of physical func- tioning. Although walking is highly important in everyday life and, therefore, is closely linked to overall functioning, an individual needs more than good walking abilities alone in order to function well. On the other hand, improving walking abilities is one of the purposes of a total hip arthroplasty. Moreover, walking speed and gait variability have been related to independent liv- ing and the ability to perform various

activities of daily living, such as safely crossing a traffic intersection, as well as to the risk of falling; there- fore, we believe that they can be used as measures of overall physical functioning.23–25

Conclusion The relationship between self-report and performance-based measures of physical functioning is poor in peo- ple before and after total hip arthro- plasty. Contrary to our hypothesis, the relationship does not appear to change over time. The finding that pain has a considerable influence on self-reported physical functioning is in accordance with our hypothesis. People appear to have problems separating pain and physical func- tioning. The practical implication is that when one is interested in physical functioning exclusively, a performance-based measure should be used. When using a self-report measure such as the WOMAC, one should realize that it does not seem to assess the separate constructs— physical functioning and pain—that are claimed to be measured.

All authors provided concept/idea/research design. Dr van den Akker-Scheek, Dr Zijlstra, and Dr Stevens provided writing. Dr van den Akker-Scheek provided data collection. Dr van den Akker-Scheek and Dr Stevens pro- vided data analysis and project manage- ment. Dr Stevens and Dr Bulstra provided fund procurement. Dr Groothoff and Dr Bul- stra provided consultation (including review of manuscript before submission).

This study was conducted in accordance with the regulations of the Medical Ethical Committee of University Medical Center Groningen.

This study was supported by a grant from University Medical Center Groningen.

This article was submitted October 3, 2006, and was accepted February 15, 2008.

DOI: 10.2522/ptj.20060301

Hip Arthroplasty and Physical Functioning

718 f Physical Therapy Volume 88 Number 6 June 2008

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

 

 

References 1 Ethgen O, Bruyere O, Richy F, et al.

Health-related quality of life in total hip and total knee arthroplasty: a qualitative and systematic review of the literature. J Bone Joint Surg Am. 2004;86:963–974.

2 Lingard E, Hashimoto H, Sledge C. Devel- opment of outcome research for total joint arthroplasty. J Orthop Sci. 2000;5:175–177.

3 Kennedy D, Stratford PW, Pagura SM, et al. Comparison of gender and group differ- ences in self-report and physical per- formance measures in total hip and knee arthroplasty candidates. J Arthroplasty. 2002;17:70 –77.

4 Steultjens MP, Roorda LD, Dekker J, Bijlsma JW. Responsiveness of observa- tional and self-report methods for assess- ing disability and mobility in patients with osteoarthritis. Arthritis Care Res. 2001;45: 56 – 61.

5 Van den Akker-Scheek I, Stevens M, Bul- stra SK, et al. Recovery of gait after short- stay total hip arthroplasty. Arch Phys Med Rehabil. 2007;88:361–367.

6 Lin YC, Davey RC, Cochrane T. Tests for physical function of the elderly with knee and hip osteoarthritis. Scand J Med Sci Sports. 2001;11:280 –286.

7 Stratford PW, Kennedy DM. Performance measures were necessary to obtain a com- plete picture of osteoarthritic patients. J Clin Epidemiol. 2006;59:160 –167.

8 Berman AT, Quinn RH, Zarro VJ. Quanti- tative gait analysis in unilateral and bilat- eral total hip replacements. Arch Phys Med Rehabil. 1991;72:190 –194.

9 Terwee CB, van der Slikke RM, Van Lum- mel RC, et al. Self-reported physical func- tioning was more influenced by pain than performance-based physical functioning in knee-osteoarthritis patients. J Clin Epi- demiol. 2006;59:724 –731.

10 Rossi MD, Hasson S, Kohia M, et al. Mobil- ity and perceived function after total knee arthroplasty. J Arthroplasty. 2006;21:6 –12.

11 Roorda LD, Jones CA, Waltz M, et al. Sat- isfactory cross-cultural equivalence of the Dutch WOMAC in patients with hip osteo- arthritis waiting for arthroplasty. Ann Rheum Dis. 2004;63:36 – 42.

12 Aaronson NK, Muller M, Cohen PD, et al. Translation, validation, and norming of the Dutch language version of the SF-36 Health Survey in community and chronic disease populations. J Clin Epidemiol. 1998;51:1055–1068.

13 Aminian K, Rezakhanlou K, De Andres E, et al. Temporal feature estimation during walking using miniature accelerometers: an analysis of gait improvement after hip arthroplasty. Med Biol Eng Comput. 1999;37:686 – 691.

14 Zijlstra W, Hof AL. Assessment of spatio- temporal gait parameters from trunk accel- erations during human walking. Gait Pos- ture. 2003;18:1–10.

15 Zijlstra W. Assessment of spatio-temporal parameters during unconstrained walking. Eur J Appl Physiol. 2004;92:39 – 44.

16 Lindemann U, Becker C, Unnewehr I, et al. Gait analysis and WOMAC are complemen- tary in assessing functional outcome in to- tal hip replacement. Clin Rehabil. 2006; 20:413– 420.

17 Twisk JWR. Applied Longitudinal Data Analysis for Epidemiology: A Practical Guide. Cambridge, United Kingdom: Uni- versity Press; 2003.

18 Parent E, Moffet H. Comparative respon- siveness of locomotor tests and question- naires used to follow early recovery after total knee arthroplasty. Arch Phys Med Re- habil. 2002;83:70 – 80.

19 Stratford PW, Kennedy D, Pagura SM, Goll- ish JD. The relationship between self- report and performance-related measures: questioning the content validity of timed tests. Arthritis Rheum. 2003;49:535–540.

20 Stratford PW, Kennedy DM. Does parallel item content on WOMAC’s pain and func- tion subscales limit its ability to detect change in functional status? BMC Muscu- loskelet Disord. 2004;5:17.

21 van den Akker-Scheek I, Zijlstra W, Groothoff JW, et al. Groningen orthopae- dic exit strategy: validation of a support program after total hip or knee arthroplas- ty. Patient Educ Couns. 2007;65:171–179. [Epub 2006 Sep 11]

22 Angst F, Aeschlimann A, Steiner W, Stucki G. Responsiveness of the WOMAC osteo- arthritis index as compared with the SF-36 in patients with osteoarthritis of the legs undergoing a comprehensive rehabilita- tion intervention. Ann Rheum Dis. 2001;60:834 – 840.

23 Bohannon RW, Andrews AW, Thomas MW. Walking speed: reference values and correlates for older adults. J Orthop Sports Phys Ther. 1996;24:86 –90.

24 Isobe Y, Okuno M, Otsuki T, Yamamoto K. Clinical study on arthroplasties for osteo- arthritic hip by quantitative gait analysis: comparison between total hip arthro- plasty and bipolar endoprosthetic arthro- plasty. Biomed Mater Eng. 1998;8: 167–175.

25 Kerrigan DC, Lee LW, Collins JJ, et al. Re- duced hip extension during walking: healthy elderly and fallers versus young adults. Arch Phys Med Rehabil. 2001; 82:26 –30.

Hip Arthroplasty and Physical Functioning

June 2008 Volume 88 Number 6 Physical Therapy f 719

D ow

nloaded from https://academ

ic.oup.com /ptj/article/88/6/712/2742310 by A

P TA

M em

ber A ccess user on 30 M

ay 2021

[checkout]

"Do you have an upcoming essay or assignment due?


If yes Order Similar Paper