The Group Experience: Remodelling Outpatient Physiotherapy after Knee Replacement Surgery.

UNLABELLED: Purpose : To estimate responses to short-duration (4-6 weeks) group-based physiotherapy after knee replacement in terms of pain, function, and satisfaction. METHOD: The study used a prospective, observational design. A total of 169 participants (111 women, 58 men) were consecutively recruited to attend a twice-weekly post-operative knee replacement class focused on mobility, strength, balance, and functional retraining. Changes in pain, function, and satisfaction were measured using the P4 pain intensity measure, the Lower Extremity Functional Scale (LEFS), a timed stair test (TST), knee range of motion (ROM), the Patient Specific Functional Scale (PSFS), and the Client Satisfaction Questionnaire (CSQ-8). Using Stata version 12.1, the data were summarized descriptively, and change scores were calculated with 95% CIs. Results : On average, participants were discharged within 11 classes, having achieved their treatment goals. More than 77% exceeded the minimal detectable change at the 90% confidence level (MDC90) on the LEFS, TST, PSFS, and ROM assessments. The mean CSQ-8 score at discharge was 31.8 (SD 1.46); 66.7% recorded a perfect score of 32. Conclusions : Patients attending a short group-based outpatient knee replacement class demonstrated significant improvements in pain and lower extremity function and were highly satisfied with their physiotherapy treatment.

Objectif : Estimer la réaction des patients à un traitement de physiothérapie en groupe de courte durée (de 4 à 6 semaines) à la suite d'une arthroplastie du genou en ce qui concerne la douleur, la fonction et la satisfaction. Méthode : L'étude a utilisé un concept prospectif d'observation. Au total, 169 patients (111 femmes) ayant subi une arthroplastie du genou ont été recrutés de façon consécutive pour assister deux fois par semaine à un cours axé sur la mobilité, la force, l'équilibre et le recyclage fonctionnel. Les changements relatifs à la douleur, à la fonction et à la satisfaction ont été mesurés à l'aide du questionnaire sur l'intensité de la douleur (P4), de l'échelle fonctionnelle des membres inférieurs (EFMI), d'un test de l'escalier chronométré (TEC), d'une mesure de l'amplitude des mouvements (ADM) du genou, de l'échelle fonctionnelle spécifique au client (EFSC) et du questionnaire de satisfaction de la clientèle (CSQ-8). À l'aide de STATA 12.1, les données ont été résumées de façon descriptive et les valeurs numériques des changements ont été calculées avec des intervalles de confiance de 95%. Résultats : En moyenne, les patients ont obtenu leur congé en 11 séances ou moins, leurs objectifs de traitement ayant été atteints. Plus de 77% des participants ont dépassé le seuil de changement détectable à un niveau de confiance de 90% (CDM90) pour les évaluations de l'EFMI, du TEC, de l'EFSC et de l'ADM. La note moyenne au CSQ-8 à l'obtention du congé était de 31,8 (ET 1,46); une note parfaite de 32 a été obtenue dans 66,7% des cas. Conclusions : Les patients ayant participé à un cours de courte durée en service externe après une arthroplastie du genou ont affiché une nette amélioration en ce qui concerne la douleur et la fonction des extrémités inférieures et se sont montrés très satisfaits de leur traitement de physiothérapie.

A comparison study of KOOS-PS and KOOS function and sport scores.

BACKGROUND: The KOOS-PS represents a shortened version of the Knee Injury and Osteoarthritis Outcome Score (KOOS) Function and Sport scales. Previous investigations have not evaluated the KOOS-PS against performance measures or self-report measures composed of items that assess a broad spectrum of ability levels. OBJECTIVE: The purpose of this study was to compare the construct validity of the KOOS Function and Sport subscales with a shorter version of the measure (KOOS-PS). METHODS: Using a cross-sectional, observational design, consecutive consenting patients diagnosed with knee osteoarthritis were recruited at an assessment center visit to determine need for conservative or surgical management. Participants completed the Lower Extremity Functional Scale (LEFS), KOOS, Timed "Up & Go" Test, and Six-Minute Walk Test. A single function-sport score (KOOS FunSportsum) and the KOOS-PS were abstracted from the KOOS. Pearson correlation coefficients were compared between the reference standards' scores (performance measures and LEFS) and KOOS scores. KOOS-PSraw scores were compared with KOOS-PSRasch scores. RESULTS: Three hundred seventy-seven patients with a mean age of 64.4 years (SD=10.5) participated. The correlation between performance reference standard and KOOS-PSRasch scores was significantly lower than with KOOS FunSportsum scores (mean difference in r=.08 [95% confidence interval=.03, .11], z=4.45, P1<.001). A similar finding was observed with the LEFS comparison. LIMITATIONS: The study sample did not consist of many patients with mild or severe functional status limitations. CONCLUSIONS: For patients with knee osteoarthritis, the KOOS-PS appears too restricted in item content to provide a comprehensive estimate of lower extremity functional status level relative to the KOOS Function and Sport subscales. Pursuit of a computer-adapted test may be a productive direction for future inquiry.

Assessing the patient-specific functional scale's ability to detect early recovery following total knee arthroplasty.

BACKGROUND: The Patient-Specific Functional Scale (PSFS) has received considerable attention over the last 2 decades; however, validation studies have not examined its performance in patients after total knee arthroplasty (TKA). OBJECTIVE: The purpose of this study was to investigate the ability of the PSFS to detect change in patients post-TKA by comparing PSFS change scores with Lower Extremity Functional Scale (LEFS) and pooled impairment change scores. METHODS: One hundred thirty-three patients participating in a post-TKA exercise class were assessed at their initial and discharge visits. Initial assessments occurred within 28 days of arthroplasty; follow-up assessments occurred within 80 days of surgery. At both assessments, participants completed the PSFS, LEFS, and the P4 pain measure, and their knee range of motion (ROM) and extensor strength were measured. The ability to detect change was expressed as the standardized response mean (SRM) and as a correlation between the PSFS change scores and 2 reference standards: (1) LEFS change scores and (2) pooled impairment change scores. The pooled impairment measure consisted of pain, ROM, and strength change scores. RESULTS: The SRMs were PSFS 4.60 (95% confidence interval [CI]=4.00, 5.36) for the PSFS and 2.28 (95% CI=2.04, 2.60) for the LEFS. The correlation between the PSFS and pooled impairment change scores was 0.12 (95% CI=-0.04, 0.25), and the correlation between the PSFS and LEFS changes scores was 0.18 (0.02, 0.34). LIMITATIONS: The order of measure administration was not standardized, and fixed activity set does not reflect clinical application in many instances. CONCLUSIONS: The results suggest that the PSFS is adept at detecting improvement in patients post-TKA but that the PSFS, like other patient-specific measures, is likely to be of limited value in distinguishing different levels of change among patients.

An example of end-digit preference in physiotherapy practice.

PURPOSE: Standardizing and improving the validity of range of motion (ROM) measurements is of clinical relevance to physiotherapists. The purpose of this study was to assess whether end-digit preference exists in the measurement of knee ROM in people after knee replacement. METHOD: Following total knee replacement, 100 people underwent active-assisted knee ROM measurements using a goniometer calibrated in 1° increments. RESULTS: The data showed strong end-digit preferences for 0s and 5s (p<0.001). CONCLUSIONS: End-digit preference does exist in the measurement of knee ROM. This has the potential to influence both the validity of ROM measurements and clinical decisions.

Objectif : Normaliser et améliorer la validité des mesures d'amplitude des mouvements (ADM) est particulièrement pertinent sur le plan clinique pour les physiothérapeutes. L'objectif de cette étude est d'évaluer si une préférence quant au dernier chiffre existe dans la mesure de l'ADM du genou chez les personnes qui ont subi un remplacement du genou. Méthodologie : À la suite d'un remplacement total du genou, 100 personnes ont subi des mesures actives assistées de l'ADM du genou à l'aide d'un goniomètre calibré selon des échelons de 1°. Résultats : Les données ont démontré une préférence marquée quant au dernier chiffre pour les 0 et les 5 (p<0,001). Conclusions : Il existe effectivement une préférence quant au dernier chiffre dans la mesure de l'ADM du genou. Cette préférence pourrait avoir une influence sur la validité des mesures d'ADM et sur les décisions cliniques.

Using outcome measure results to facilitate clinical decisions the first year after total hip arthroplasty.

STUDY DESIGN: Variable-occasion, repeated-measures design. OBJECTIVES: To model change in lower extremity functional status of patients 1 year after total hip arthroplasty (THA), using the Lower Extremity Functional Scale (LEFS) and the 6-minute walk test (6MWT), and, secondarily, to provide clinicians with useful data to guide practice. BACKGROUND: Given the prevalence of THA and current resource pressures, standardized outcome measures play an important role in providing physical therapists with objective knowledge about postoperative recovery and prognosis. METHODS: Seventy-five patients, with a mean age of 61 years and a diagnosis of hip osteoarthritis, consented to participate in the study. Assessments were conducted preoperatively and at multiple time points for up to 65 weeks postoperatively. Recovery was modeled using a nonlinear robust regression analysis for clustered data. The predictive ability of age, body mass index, and preoperative score was explored. RESULTS: Gender-based recovery curves were generated to depict the rate and amount of change in LEFS scores and 6MWT distances over the first year. Preoperative baseline 6MWT distance was the only covariate predictive of postarthroplasty 6MWT distances for both males and females. None of the covariates examined were significantly associated with postarthroplasty LEFS scores. CONCLUSION: Although there were variations in the recovery curves by measure, general patterns were noted. There was a rapid increase in both self-reported and physical performance measure scores for 12 to 15 weeks. Thereafter, we observed a slowing of recovery, with a plateau at 30 to 35 weeks for the 6MWT and later for the LEFS. These data can be used to make evidence-based decisions regarding prognosis and to guide the setting of measurable treatment goals. LEVEL OF EVIDENCE: Prognosis, level 1b.

Quantifying self-report measures' overestimation of mobility scores postarthroplasty.

BACKGROUND: Self-reports of function may systematically overestimate the ability of patients to move around postarthroplasty. OBJECTIVE: The purpose of this study was to estimate the magnitude of systematic differences in Lower Extremity Functional Scale (LEFS) and Western Ontario and McMaster Universities Osteoarthritis Index physical function subscale (WOMAC-PF) scores before and after primary total knee arthroplasty (TKA) or total hip arthroplasty (THA) by referencing the values to Six-Minute Walk Test (6MWT) distances and Timed "Up & Go" Test (TUG) times. DESIGN: This study was a secondary analysis of data from a prospective cohort study. METHODS: The LEFS, WOMAC, 6MWT, and TUG were administered to 85 patients prearthroplasty and once at 9 to 13 weeks postarthroplasty. Regression analysis was applied using a robust error term for clustered data. With the self-report measures as dependent variables and performance measures, occasion (prearthroplasty or postarthroplasty), and performance measure-by-occasion as independent variables, 3 propositions were examined: (1) the relationship between self-report and performance measures is identical prearthroplasty and postarthroplasty (ie, regression lines are coincident); (2) the relationship differs between occasions, but is consistent (ie, regression lines are parallel); (3) the relationship is not consistent (ie, the regression lines are not parallel). RESULTS: For all analyses, the results supported the second proposition (ie, the relationship differed between occasions, but was consistent). The systematic differences varied by location of arthroplasty, but were similar for both performance tests. For the LEFS, the difference was approximately 11 points for patients who received TKA and 13 points for patients who received THA. For the WOMAC-PF, the difference was approximately 12 points for patients who received TKA and 19 points for patients who received THA. These differences exceed the minimal clinically important change for an individual patient. LIMITATIONS: The findings are specific to 9 to 13 weeks postarthroplasty. CONCLUSION: Dependence on scores of self-report measures alone, without knowledge of the magnitude of the identified systematic differences, will result in overestimating the ability of patients to move around postarthroplasty.

Patients are satisfied with advanced practice physiotherapists in a role traditionally performed by orthopaedic surgeons.

PURPOSE: To measure and compare patient satisfaction with follow-up care in advanced practice physiotherapist (APP) and orthopaedic surgeon clinics for patients following total hip or knee replacement. METHOD: Consecutive patients attending either an APP-led or a surgeon-led review clinic were surveyed using a modified nine-item satisfaction questionnaire based on the Visit-Specific Satisfaction Instrument (VSQ-9). Chi-square analyses were used to examine differences in patient characteristics and type of visit. Independent t-tests were used to examine potential differences in patient satisfaction. RESULTS: Of the 123 participants, more than half were aged 65 years or older. Chi-squared analyses revealed no significant difference in participant characteristics (gender, age, and overall health status) between the two different types of clinics. There was a significant difference (χ(2) (4)=12.49, p=0.014) in the distribution of the timing of follow-up appointments. There was no significant difference between the groups in mean overall patient satisfaction scores on the modified VSQ-9 (p=0.34) nor in the mean of the sum of the seven items related to the service provider (p=0.85). Satisfaction scores for most of the service-provider items were above 90/100. CONCLUSION: Patients are highly satisfied with the care provided by APPs in follow-up clinics after joint replacement. Evaluation of the patient perspective is essential to any new role involving a shift in traditional practice boundaries.

Modelling knee range of motion post arthroplasty: clinical applications.

PURPOSE: To model change in knee range of motion (ROM) post total knee arthroplasty (TKA) and to show how this information can be incorporated into clinical decision making. METHOD: We applied a variable-occasion repeated-measures study design. Patients' knee flexion and extension ROM were assessed pre- and post arthroplasty over the ensuing 60 weeks. We examined change in ROM post TKA using linear and nonlinear mixed-effects modelling, and examined whether age, body mass index, prearthroplasty ROM, and gender were determinants of recovery in post-arthroplasty ROM. RESULTS: Of 93 eligible patients, 74 provided pre- and post-arthroplasty data. A random intercept nonlinear model fit the flexion data best, and a random intercept linear model fit the extension data best. Pre-arthroplasty ROM was found to be a determinant of recovery in ROM post arthroplasty. This finding was common to both flexion and extension models. CONCLUSIONS: Our study showed that the greatest improvement for knee ROM took place during the first 12 weeks post arthroplasty. Of the variables examined, only pre-arthroplasty ROM was a determinant of outcome (p<0.05). The study results provide clinicians with data to determine expected rates of improvement for patients as well as the projected maximum ROM, facilitating improved clinical decision making.

Using hierarchical linear modeling to explore predictors of pain after total hip and knee arthroplasty as a consequence of osteoarthritis.

Hierarchical linear modeling was used to establish differences in, and the average pattern of, recovery of the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and 2 composite performance-specific measures of pain as well as to determine if significant individual variations exist in the growth curves for each measure. Predictors of postoperative pain were also of interest. One hundred forty-seven patients undergoing unilateral primary hip or knee arthroplasty completed 4 performance measures-self-paced 40-m walk, timed up and go, stair test, and 6-minute walk-and the WOMAC prearthroplasty and at multiple points in time between 2 and 27 weeks postarthroplasty. Although patients reported different levels of postoperative pain initially, similar recovery patterns were noted. Predictive variables were found to be site of joint arthroplasty and WOMAC prearthroplasty pain scores for the WOMAC pain subscale, the site of joint arthroplasty and sex for the first composite pain score, and sex for the second composite.

New study design evaluated the validity of measures to assess change after hip or knee arthroplasty.

OBJECTIVE: We propose a study design to evaluate the ability of measures to assess physical function relatively independent of pain. We illustrate the design using data from patients scheduled for total hip (THA) or knee (TKA) arthroplasty. STUDY DESIGN AND SETTING: A repeated-measure study design was developed and applied to patients undergoing THA or TKA. A performance battery (PB) (walking, stair, and timed-up-and-go) was used as the gold standard measure for "physical function." Recent evidence indicates physical performance deteriorates 1 month after surgery compared to presurgical measures and patients with THA deteriorate to a greater extent than patients with TKA. Our design assessed whether the results from self-report measures (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC] and the Lower Extremity Functional Scale [LEFS]) of physical function were consistent with changes found using the PB. RESULTS: The performance measures demonstrated significant Occasion (pre- to 1 month postarthroplasty) and Group (hip vs. knee)-by-Occasion effects; the LEFS showed a significant Occasion effect; and the WOMAC PF showed neither. CONCLUSION: Our findings support the proposed design in that the PB was more sensitive to change than the self-report measures.

Validating self-report measures of pain and function in patients undergoing hip or knee arthroplasty.

PURPOSE: To investigate the factorial and construct validity of a four-item pain intensity scale, the P4, in patients awaiting primary total hip or knee arthroplasty secondary to osteoarthritis. METHOD: A construct validation design was applied to a sample of convenience of 117 patients (mean age 65.6 [SD = 11.2] years) at their preoperative visit. All patients completed the P4 and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Exploratory and confirmatory factor analyses were used to examine the factorial structure of the P4 and WOMAC. To evaluate construct validity, we examined the correlation between the P4 and WOMAC pain sub-scales and the ability of the P4 to differentiate between patients awaiting hip and knee replacement. RESULTS: Two distinct factors consistent with the themes of pain and function were identified with P4 and WOMAC physical function items, but not with the WOMAC pain and physical function items. The P4 correlates more with the WOMAC pain scores (r = 0.67) than with the WOMAC physical function scores (r = 0.60). CONCLUSION: The P4's validity was supported in this patient group. The use of the P4 with the WOMAC physical function sub-scale provides a more distinct assessment of pain and function than the WOMAC pain and physical function scales.

Measurement properties of performance-specific pain ratings of patients awaiting total joint arthroplasty as a consequence of osteoarthritis.

PURPOSE: To estimate the test-retest reliability of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain sub-scale and performance-specific assessments of pain, as well as the association between these measures for patients awaiting primary total hip or knee arthroplasty as a consequence of osteoarthritis. METHODS: A total of 164 patients awaiting unilateral primary hip or knee arthroplasty completed four performance measures (self-paced walk, timed up and go, stair test, six-minute walk) and the WOMAC. Scores for 22 of these patients provided test-retest reliability data. Estimates of test-retest reliability (Type 2,1 intraclass correlation coefficient [ICC] and standard error of measurement [SEM]) and the association between measures were examined. RESULTS: ICC values for individual performance-specific pain ratings were between 0.70 and 0.86; SEM values were between 0.97 and 1.33 pain points. ICC estimates for the four-item performance pain ratings and the WOMAC pain sub-scale were 0.82 and 0.57 respectively. The correlation between the sum of the pain scores for the four performance measures and the WOMAC pain sub-scale was 0.62. CONCLUSION: Reliability estimates for the performance-specific assessments of pain using the numeric pain rating scale were consistent with values reported for patients with a spectrum of musculoskeletal conditions. The reliability estimate for the WOMAC pain sub-scale was lower than typically reported in the literature. The level of association between the WOMAC pain sub-scale and the various performance-specific pain scales suggests that the scores can be used interchangeably when applied to groups but not for individual patients.

Assessing recovery and establishing prognosis following total knee arthroplasty.

BACKGROUND AND PURPOSE: Information about expected rate of change after arthroplasty is critical for making prognostic decisions related to rehabilitation. The goals of this study were: (1) to describe the pattern of change in lower-extremity functional status of patients over a 1-year period after total knee arthroplasty (TKA) and (2) to describe the effect of preoperative functional status on change over time. SUBJECTS: Eighty-four patients (44 female, 40 male) with osteoarthritis, mean age of 66 years (SD=9), participated. METHODS: Repeated measurements for the Lower Extremity Functional Scale (LEFS) and the Six-Minute Walk Test (6MWT) were taken over a 1-year period. Data were plotted to examine the pattern of change over time. Different models of recovery were explored using nonlinear mixed-effects modeling that accounted for preoperative status and gender. RESULTS: Growth curves were generated that depict the rate and amount of change in LEFS scores and 6MWT distances up to 1 year following TKA. The curves account for preoperative status and gender differences across participants. DISCUSSION AND CONCLUSION: The greatest improvement occurred in the first 12 weeks after TKA. Slower improvement continued to occur from 12 weeks to 26 weeks after TKA, and little improvement occurred beyond 26 weeks after TKA. The findings can be used by physical therapists to make prognostic judgments related to the expected rate of improvement following TKA and the total amount of improvement that may be expected.

Modeling early recovery of physical function following hip and knee arthroplasty.

BACKGROUND: Information on early recovery after arthroplasty is needed to help benchmark progress and make appropriate decisions concerning patient rehabilitation needs. The purpose of this study was to model early recovery of physical function in patients undergoing total hip (THA) and knee (TKA) arthroplasty, using physical performance and self-report measures. METHODS: A sample of convenience of 152 subjects completed testing, of which 69 (mean age: 66.77 +/- 8.23 years) underwent THA and 83 (mean age: 60.25 +/- 11.19 years) TKA. Postoperatively, patients were treated using standardized care pathways and rehabilitation protocols. Using a repeated measures design, patients were assessed at multiple time points over the first four postoperative months. Outcome measures included the Lower Extremity Function Scale (LEFS), the physical function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC PF), the 6 minute walk test (6 MWT), timed up and go test (TUG) and a timed stair test (ST). Average recovery curves for each of the measures were characterized using hierarchical linear modeling. Predictors of recovery were sequentially modeled after validation of the basic developmental models. RESULTS: Slopes of recovery were greater in the first 6 to 9 weeks with a second-degree polynomial growth term (weeks squared) providing a reasonable fit for the data over the study interval. Different patterns of recovery were observed between the self-report measures of physical function and the performance measures. In contrast to the models for the WOMAC PF and the LEFS, site of arthroplasty was a significant predictor (p = 0.001) in all of the physical performance measure models with the patients post TKA initially demonstrating higher function. Site of arthroplasty (p = 0.025) also predicted the rate of change for patients post THA and between 9 to 11 weeks after surgery, the THA group surpassed the function of the patients post TKA. CONCLUSION: Knowledge about the predicted growth curves will assist clinicians in referencing patient progress, and determining the critical time points for measuring change. The study has contributed further evidence to highlight the benefit of using physical performance measures to learn about the patients' actual level of disability.

Performance measures provide assessments of pain and function in people with advanced osteoarthritis of the hip or knee.

BACKGROUND AND PURPOSE: Pain and physical function are core outcome measures for people with osteoarthritis, and self-report questionnaires have been the preferred assessment method. There is evidence suggesting that self-reports of physical function represent what people experience when performing activities rather than their ability to perform activities. The purpose of this study was to examine the factorial validity of performance-specific assessments of pain and function. SUBJECTS: The sample consisted of 177 participants who had osteoarthritis of the hip (n=81) or knee (n=96) and who were awaiting total joint arthroplasty. METHODS: Through a cross-sectional design, participants performed 4 performance activities (self-paced walk test, stair test, Timed "Up & Go" Test, and Six-Minute Walk Test). OUTCOMES: were time or distance (function) and pain ratings obtained immediately after each activity. The authors conceptualized 2 correlated factors, with pain items loading uniquely on 1 factor and functional items loading on the second factor, and uncorrelated error terms. Confirmatory factor analysis was applied. RESULTS: Initial analysis yielded results consistent with the conceptualized model in this study with the exception of a nonzero correlation between the stair pain and function error terms. Dropping the stair test provided results consistent with the conceptualized model. DISCUSSION AND CONCLUSION: Given the limitations of self-report alone as a method of obtaining reasonably distinct assessments of pain and function, the extent to which performance-specific assessments could accomplish this goal was examined in this study. It was found that collectively the walk test, Timed "Up & Go" Test, and Six-Minute Walk Test yielded 2 factors consistent with the health concepts of pain and function. The authors believe that the application of these tests may provide clinicians and clinical researchers with more distinct impressions of pain and function that complement information from self-report measures.

Preoperative function and gender predict pattern of functional recovery after hip and knee arthroplasty.

Gender, preoperative function, and other variables were explored as predictors of recovery after total hip and knee arthroplasty. One hundred fifty-two subjects (63.8 +/- 10.2 years) were repeatedly assessed in the first 4 postoperative months. Average recovery curves for the Western Ontario and McMaster Universities Osteoarthritis Index, 6-minute walk test, and timed up and go test were characterized using hierarchical linear modeling. Recovery predictors were sequentially modeled after validation of the basic developmental models. Gender was a significant predictor (P < or= .003) of physical performance measure scores 1 week after surgery. Thereafter, men and women had similar rates of improvement. Preoperative score was a significant predictor (P < or= .001) in all models. Patients' and surgeons' expectations of outcome need to take preoperative function into account.

Performance measures were necessary to obtain a complete picture of osteoarthritic patients.

OBJECTIVES: Self-report questionnaires and performance measures represent two methods for assessing physical function. A recurring theme is that self-report measures are superior to performance measures. This study investigated the association between three performance test outcomes of four activities (pain, exertion, and time or distance; for self-paced walk, stair test, timed up-and-go, 6-minute walk) with self-reports of physical function (WOMAC Physical Function subscale and LEFS) and the association between the change scores of the performance tests and those of the self-report measures. STUDY DESIGN AND SETTING: Performance and self-report measures were administered three times (presurgery and at approximately 1 week and approximately 8 weeks post arthroplasty) to 85 patients who underwent total hip or knee arthroplasty. Components of the performance tests were pooled within each domain across the four measures. Multiple regression analyses were applied. Independent variables were performance tests components; dependent variables were self-report measures. Standardized regression coefficients described the cross-sectional and longitudinal associations. RESULTS: Pain was the principal determinant of WOMAC Physical Function subscale scores. Pain, exertion, and time or distance were strongly associated with the LEFS at the first, second, and third assessments, respectively. Change in pain was most strongly associated with change in self-reported physical function. CONCLUSION: Our findings caution against the isolated use of self-report assessments of physical function.

Assessing stability and change of four performance measures: a longitudinal study evaluating outcome following total hip and knee arthroplasty.

BACKGROUND: Physical performance measures play an important role in the measurement of outcome in patients undergoing hip and knee arthroplasty. However, many of the commonly used measures lack information on their psychometric properties in this population. The purposes of this study were to examine the reliability and sensitivity to change of the six minute walk test (6MWT), timed up and go test (TUG), stair measure (ST), and a fast self-paced walk test (SPWT) in patients with hip or knee osteoarthritis (OA) who subsequently underwent total joint arthroplasty. METHODS: A sample of convenience of 150 eligible patients, part of an ongoing, larger observational study, was selected. This included 69 subjects who had a diagnosis of hip OA and 81 diagnosed with knee OA with an overall mean age of 63.7 +/- 10.7 years. Test-retest reliability, using Shrout and Fleiss Type 2,1 intraclass correlations (ICCs), was assessed preoperatively in a sub-sample of 21 patients at 3 time points during the waiting period prior to surgery. Error associated with the measures' scores and the minimal detectable change at the 90% confidence level was determined. A construct validation process was applied to evaluate the measures' abilities to detect deterioration and improvement at two different time points post-operatively. The standardized response mean (SRM) was used to quantify change for all measures for the two change intervals. Bootstrapping was used to estimate the 95% confidence intervals (CI) for the SRMs. RESULTS: The ICCs (95% CI) were as follows: 6MWT 0.94 (0.88,0.98), TUG 0.75 (0.51, 0.89), ST 0.90 (0.79, 0.96), and the SPWT 0.91 (0.81, 0.97). Standardized response means varied from .79 to 1.98, being greatest for the ST and 6MWT over the studied time intervals. CONCLUSIONS: The test-retest estimates of the 6MWT, ST, and the SPWT met the requisite standards for making decisions at the individual patient level. All measures were responsive to detecting deterioration and improvement in the early postoperative period.

Condition-specific Western Ontario McMaster Osteoarthritis Index was not superior to region-specific Lower Extremity Functional Scale at detecting change.

OBJECTIVE: We determined whether the sensitivity to change of the Western Ontario McMaster Osteoarthritis Index (WOMAC) physical function (PF) subscale, a condition-specific measure for persons with osteoarthritis of the hip or knee, was superior to a lower extremity region-specific measure, the Lower Extremity Functional Scale (LEFS), in persons with osteoarthritis of the hip or knee undergoing total joint arthroplasty. METHODS: The WOMAC and LEFS were administered to 102 patients with osteoarthritis preoperatively, within 16 days of surgery, and >20 days after the first postoperative assessment. These time points enabled the assessment of deterioration and improvement. Two timed performance measures (40 m walk test and the timed-up-and-go test) were also assessed. Change was quantified by the standardized response mean (SRM). RESULTS: WOMAC PF SRMs were not greater than the LEFS SRMs. Performance measures' times increased significantly over the deterioration interval and decreased over the improvement interval. The WOMAC PF and LEFS demonstrated significant improvement over the second assessment interval; only the LEFS showed significant deterioration over the first assessment interval. WOMAC PF scores seem to be strongly influenced by pain. CONCLUSION: The findings do not support the hypothesis that the WOMAC PF subscale is superior to the LEFS in detecting change.

Does parallel item content on WOMAC's pain and function subscales limit its ability to detect change in functional status?

BACKGROUND: Although the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) is considered the leading outcome measure for patients with osteoarthritis of the lower extremity, recent work has challenged its factorial validity and the physical function subscale's ability to detect valid change when pain and function display different profiles of change. This study examined the etiology of the WOMAC's physical function subscale's limited ability to detect change in the presence of discordant changes for pain and function. We hypothesized that the duplication of some items on the WOMAC's pain and function subscales contributed to this shortcoming. METHODS: Two eight-item physical function scales were abstracted from the WOMAC's 17-item physical function subscale: one contained activities and themes that were duplicated on the pain subscale (SIMILAR-8); the other version avoided overlapping activities (DISSIMILAR-8). Factorial validity of the shortened measures was assessed on 310 patients awaiting hip or knee arthroplasty. The shortened measures' abilities to detect change were examined on a sample of 104 patients following primary hip or knee arthroplasty. The WOMAC and three performance measures that included activity specific pain assessments--40 m walk test, stair test, and timed-up-and-go test--were administered preoperatively, within 16 days of hip or knee arthroplasty, and at an interval of greater than 20 days following the first post-surgical assessment. Standardized response means were used to quantify change. RESULTS: The SIMILAR-8 did not demonstrate factorial validity; however, the factorial structure of the DISSIMILAR-8 was supported. The time to complete the performance measures more than doubled between the preoperative and first postoperative assessments supporting the theory that lower extremity functional status diminished over this interval. The DISSIMILAR-8 detected this deterioration in functional status; however, no significant change was noted for the SIMILAR-8. The WOMAC pain scale demonstrated a slight reduction in pain and the performance specific pain measures did not reflect a change in pain. All measures showed substantial improvement over the second assessment interval. CONCLUSIONS: These findings support the hypothesis that activity overlap on the pain and function subscales plays a causal role in limiting the WOMAC physical function subscale's ability to detect change.