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Reproducibility and validity of the DynaPort KneeTest
Abstract
To determine the reproducibility and validity of the DynaPort KneeTest, a performance-based test that measures quality of movement of patients undergoing total knee replacement (TKR).
A total of 92 patients with osteoarthritis (OA) of the knee performed the KneeTest twice on the same day; 94 healthy controls performed the KneeTest once. During the test, 29 activities were performed with accelerometers attached to the body. Relevant functional parameters were extracted from the accelerometers. A selection of parameters was used to calculate activity scores, based on the ability of parameters to discriminate between patients and controls (regression analyses). Based on internal consistency analyses (Cronbach's alpha), redundant activities were removed. Four cluster scores and a total KneeScore were calculated from the remaining activity scores. Reproducibility and validity of the cluster scores and the total KneeScore 2 were assessed.
Based on internal consistency analyses, the test was reduced to 23 activities. Inter- and intraobserver reliability using intraclass correlation coefficients were 0.90 (0.83-0.94) and 0.95 (0.83-0.98), respectively. Limits of inter- and intraobserver agreement were -8.3 to 11.3 and -4.2 to 9.0. Construct validity was confirmed by expected correlations with the Western Ontario and McMaster University Osteoarthritis Index physical functioning (0.55), Medical Outcomes Study Short Form-36 Health Survey physical functioning (0.62), and Knee Society Score function (0.64).
The KneeTest is a useful performance-based measure for research in patients with knee OA undergoing TKR, with good reliability and validity. Further research is required to improve its usefulness for clinical practice.
... The DynaPort Ò KneeTest (DPKT), an accelerometerbased system, was developed to objectively assess knee-related functional abilities in an unobtrusive, userfriendly way [18]. This test has proved to be a useful performance-based instrument for use in patients with knee osteoarthritis undergoing a total knee replacement, showing good reliability and validity [19,20]. However, the validity of the DPKT for patients with knee complaints in general practice is not yet known. ...
... A modified score (KneeScore2) was recently developed and presented by Mokkink et al. [19]. In this score, based on internal consistency analysis, the test was reduced to 23 activities and provided a more precise estimate of the knee function. ...
... If the DPKT was found not to be valid, we would then compare our primary care population with a secondary care population in which the DPKT was previously shown to be valid [19]. ...
... We compared the validated DynaPort Ò KneeTest (DPKT) (McRoberts B.V., The Hague, The Netherlands)181920 as a performance-based measure of physical functioning with the self-report WOMAC [16] subscale physical functioning and the self-report MOS SF-36 [17] subscale physical functioning, in subgroups of knee-OA patients with different levels of pain, as measured with the WOMAC and SF-36 pain subscales. ...
... They perform 23 activities in the test, such as walking, stair climbing, stepping up, and sitting down on blocks of different heights. In a recent validation study, the test was shortened from 29 to 23 activities and the scoring system was slightly modified (see Appendix) [18] . During the performance of the activities, the signals from the accelerometers are stored in a portable datarecorder. ...
... rson is below or above the mean score of a control group of ''healthy'' subjects . The scoring algorithm (including the data of the control group) is available from the authors. Construct validity was supported by a high correlation between the DPKT KneeScore2 and the physical therapists' opinion of the patients' quality of movement (r 5 0.68–0.86) [18,19]. Because the DPKT appeared to be highly reliable (ICC for intertester reliability was 0.90 [95% CI 0.83–0.94]) [18], lack of reliability cannot be an explanation for the modest correlation between the self-report measures of physical functioning and the performance-based measure of physical functioning in this study. ...
To test the hypothesis that self-reported physical functioning is more influenced by pain than performance-based physical functioning.
163 knee-osteoarthritis patients completed the performance-based DynaPort KneeTest (DPKT), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and SF-36 (self-report measures of pain and physical functioning) before, 3, 6, and 12 months after knee replacement.
Correlations between (two) self-reported measures of functioning and (two) pain measures were higher (0.57-0.74) than correlations between the performance-based measure of functioning and the two pain measures (0.20 and 0.26). In factor analysis, WOMAC and SF-36 pain and physical functioning subscores loaded on the first factor (eigenvalue 3.2), while DPKT KneeScore2 loaded on the second factor (eigenvalue 0.92). Before surgery, correlations between performance-based and self-reported physical functioning were higher in patients with less pain (0.43) compared to patients with more pain (0.17), for the WOMAC (as expected), but not for the SF-36. After surgery, when the pain had diminished, the correlations between performance-based and self-reported physical functioning were higher, especially for the WOMAC.
Our hypothesis was convincingly supported by the results of the WOMAC, and somewhat less by the results of the SF-36. We consider this as evidence for a lack of content validity of the WOMAC.
... The DynaPort ® Knee Test (DKT, McRoberts, The Hague, the Netherlands) is a joint-specific performancebased measure which is useful for research in patients undergoing TKA [25]. This test was found to be reliable and valid [25,26]. ...
... The DynaPort ® Knee Test (DKT, McRoberts, The Hague, the Netherlands) is a joint-specific performancebased measure which is useful for research in patients undergoing TKA [25]. This test was found to be reliable and valid [25,26]. The test-retest reliability ICC was 0.81 (95 % CI 0.69-0.93) ...
The Oxford Knee Score (OKS) is a widely known patient-related outcome measure (PROM) to determine pain and knee functioning before and after total knee arthroplasty (TKA). Self-reported function is mainly influenced by change in pain; therefore, it was hypothesized that the OKS correlates more with pain than with performance-based functioning.
In a prospective cohort of 88 patients, who had a cementless mobile-bearing TKA, included in a randomized clinical trial, the correlation between the overall OKS, and its subscales for pain (PCS) and function (FCS), with performance-based functioning using the DynaPort(®) Knee Score (DKS), visual analogue scale score for pain (VAS) and the Knee Society Score (KSS) was evaluated. All scores were measured preoperatively, 6 months and 1 year after surgery. Overall change in outcome over time was analysed until 5 years after surgery.
All scores improved over time. The DKS was influenced by sex, preoperative BMI and age. The internal consistency of the OKS PCS increased over time, whereas the OKS FCS remained the same. The mean postoperative OKS FCS showed moderate correlation with the DKS (r = 0.65, p < 0.001), and the mean postoperative OKS and OKS PCS showed high correlation with the VAS (r = -0.79 and r = -0.82, respectively, p < 0.001). The mean postoperative KSS showed high correlations with the OKS (r = 0.80, p < 0.001), the OKS PCS (r = 0.72 p < 0.001) and OKS FCS (r = 0.74, p < 0.001).
The postoperative OKS and the OKS PCS showed high correlation with pain, but only the postoperative OKS FCS was well correlated with performance-based functioning. This suggests that the OKS is more related to pain and tells us less on postoperative functioning. This is important when the OKS as PROM is used to evaluate the quality of orthopaedic care of patients with TKA.
III.
... Vertical and saggital plane accelerations during 29 activities (later reduced to 23 (Mokkink et al., 2005) were monitored by the 6 accelerometers and stored in a data logger worn around the subjects waist. Raw accelerometer data was converted into 30 'signal properties' which included accelerations, angles and temporal parameters of gait. ...
... The study used the Dynaport test (van den Dikkenberg et al, 2002) which uses accelerometers to measure function during a range of activities of daily living. Although not widely used in outcome studies, the Dynaport test has been thoroughly tested for validity and reliability (Mokkink et al, 2005). The results of correlational analysis of the Dynaport test with WOMAC showed only low levels of association between function and stiffness (r = 0.216) but no indication was given of the associated p-value. ...
Studies show that Total Knee Arthroplasty (TKA) is successful for
the majority of patients however some continue to experience some functional
limitations and anecdotal evidence indicates that stiffness is a common complaint.
Some studies have suggested an association between stiffness and functional
limitations however there has been no previous work which has attempted to
objectively quantify knee joint stiffness following TKA. The purpose of this study
was to pilot and evaluate a method for the quantitative evaluation in joint stiffness in
replaced knees, OA knees and healthy controls and to explore whether there is an
association between stiffness and functional limitations post-TKA surgery.
Methods: The first part of the study created a biomechanical model of knee
stiffness and built a system from which stiffness could be calculated. A torque
transducer was used to measure the resistance as the knee was flexed and extended
passively and an electrogoniometer concurrently measured the angular displacement.
Stiffness was calculated from the slope of the line relating the passive resistive
torque and displacement. The torque and joint angle at which stiffness was seen to
increase greatly was also noted. The system was bench tested and found to be
reliable and valid. Further tests on 6 volunteers found stiffness calculations to have
acceptable intra-day reliability.
The second part was conducted on three groups: those with end-stage knee OA (n =
8); those who were 1 year post-TKA (n = 15) and age matched healthy controls (n =
12). Knee range of motion was recorded and participants then completed the
WOMAC, the SF-12 and a Visual Analogue Score for stiffness as well as indicating
words to describe their stiffness. Four performance based tests – the Timed Up and Go (TUG), the stair ascent/descent, the 13m walk and a quadriceps strength test were
also undertaken. Finally, passive stiffness at the affected knee was measured.
Results: 100% of OA, 80% of TKA and 58% of controls reported some stiffness at
the knee. The OA group reported significantly higher stiffness than the OA or TKA
groups. There was no difference in self-reported stiffness between the TKA and
control groups. Of the total number of words used to describe stiffness, 52% related
to difficulty with movement, 35% were pain related and 13% related to sensations.
No significantly differences were found between groups in the objective stiffness
measures. Significant differences were found however in threshold flexion stiffness
angles between groups. When this angle was normalised, differences between groups
were not significant. No significant differences were found between groups in the
threshold stiffness torque. Greater self-reported stiffness was found to be associated
with worse self-reported function. A higher flexion stiffness threshold angle was
associated with slower timed tests of function but also with better quadriceps muscle
strength.
Conclusions: The results support anecdotal reports that perceived stiffness is a
common complaint following TKA but there was no evidence to show that patients
with TKA have greater stiffness than a control group. There was however evidence
to show that patients’ were unable to distinguish between sensations of stiffness and
other factors such as pain. Self-perceived increased stiffness was associated with
worse functional performance. Greater stiffness however was not necessarily
negative. Stiffness increases earlier in flexion range were associated with better
functional performance. These results suggest that an ideal threshold range for
stiffness may exist; above which negative perceptions of the knee result in worse
function but below which, knee laxity and instability may also result in worse
function.
... In contrast, self-reported measures of physical function made using knee arthritisespecific instruments such as the WOMAC physical function and the KOS-ADL tend to be more strongly influenced (r ¼ 0.53-0.74) by the amount of pain experienced by people who have had TKA [7,31]. As pain subsides, the perception of the functional ability increases, even in the presence of continued impairments such as quadriceps weakness, joint stiffness, and swelling [7]. ...
Background
The Patient Reported Outcomes Measurement Information System (PROMIS) Computerized Adaptive Test (CAT) physical function rapidly assesses self-reported function capability. The Timed Up and Go (TUG) test is often used in clinical practice, but administration may be impeded by space and patient limitations. PROMIS CAT can potentially address these limitations, but we lack evidence if TUG and health indicators are predictors of PROMIS CAT. This study assessed whether TUG, body mass index (BMI), numeric pain rating scale (NPRS), and smoking status were predictors of PROMIS CAT in total knee arthroplasty (TKA) candidates.
Methods
Sixty-five TKA candidates completed the PROMIS CAT physical function test using an iPad application. TUG, NPRS, BMI, and smoking status were obtained at the clinic visit or from medical records. Univariate and multiple regression analyses identified the strongest predictors of PROMIS CAT.
Results
TUG was the best predictor of PROMIS CAT physical function based on simple regression (r = −0.43, 95% CI = −0.62 to −0.20) or multiple regression (βˆ = −0.45, 95% CI = −0.73 to −0.17) analyses. BMI and NPRS did not incrementally help predict the PROMIS score beyond TUG. Smoking status did not contribute to the prediction of the PROMIS CAT score.
Conclusions
The findings suggest that the PROMIS CAT physical function is not a surrogate for the TUG performance-based measure in candidates for TKA. However, TUG was the best predictor of PROMIS physical function compared with BMI, NPRS, and smoking status. Clinicians should consider both patient-reported and performance-based measures when evaluating function for TKA outcomes.
... Unfortunately, those scores can hardly be transformed into useful expressions beyond comparisons, as the authors mention in their paper. Validations of the DPKT show good results [12,13] but angular rotation, considered to be of high importance by physicians, cannot be analyzed by the DPKT directly [14]. As a system developed for lab use, no statement can be made about the quality of gait and knee motion during everyday life of the patients. ...
Osteoarthritis has the highest prevalence in the elderly population, with a rising tendency. Currently often special gait labs are used for objective diagnostic assessment of functional motion deficits or treatment outcome, e.g in patients suffering from gonarthrosis. The artificial lab setting and short measurement periods affect the explanatory power of this method. Inertial multi-sensor systems in contrast allow for monitoring human gait independent of a lab setting. However, recent approaches concerning important knee function parameter analyses have not been validated for long-term monitoring yet.
... Unfortunately, those scores can hardly be transformed into useful expressions beyond comparisons, as the authors mention in their paper. Validations of the DPKT show good results [18, 19] but angular rotation, considered to be of high ...
Patients suffering from end-stage knee osteoarthritis are often treated with total knee arthroplasty, improving their functional mobility. A number of patients, however, report continued difficulty with stair ascent and descent or sportive activity after surgery and are not completely satisfied with the outcome. State-of-the-art analyses to evaluate the outcome and mobility after knee replacement are conducted under supervised settings in specialized gait labs and thus can only reflect a short period of time. A number of external factors may lead to artificial gait patterns in patients. Moreover, clinically relevant situations are difficult to simulate in a stationary gait lab. In contrast to this, inertial sensors may be used additionally for unobtrusive gait monitoring. However, recent notable approaches found in literature concerning knee function analysis have so far not been applied in a clinical context and have therefore not yet been validated in a clinical setting.
... Unfortunately, those scores can hardly be transformed into useful expressions beyond comparisons, as the authors mention in their paper. Validations of the DPKT show good results [12,13] but angular rotation, considered to be of high importance by physicians, cannot be analyzed by the DPKT directly [14]. As a system developed for lab use, no statement can be made about the quality of gait and knee motion during everyday life of the patients. ...
Introduction
Within the scope of knee endoprostheses, some knee joint problems may not be recognizable during the short periods of clinical visits. Ambulatory sensor-based monitoring can provide assessment of knee function during ordinary daily activities as well as may serve to identify marginal changes in everyday life motion parameters. The aim of this contribution is to present a system for unobtrusive, unsupervised long-term monitoring of human gait with a focus on knee joint function, which has been validated in a clinical setting and is now applied in a clinical study.
Methods
We use three SHIMMER sensors (including accelerometer, gyroscope and magnetometer) worn under normal trousers and attached to the patient’s pelvis, thigh and shank with kinesiotape. The sensor data are transmitted via Bluetooth. Raw data recording takes place in parallel mode and the software system provides the timestamp for synchronisation of the sensor units. The coordinate systems of the sensor axes are transformed to the coordinate systems of the bone axes. Since offset and sensitivity of the sensors may vary with temperature and battery charge, the data are calibrated frequently. The system has a (simplified) real-time and a post-visualization interface to support clinicians in interpreting and analyzing the data, and also in identifying pathological motion patterns.
Results
Reliability tests concerning knee joint function were performed in a clinical validation study against a state-of-the-art lab-based vision system with five knee surgery patients walking a distance of 15m at three self-selected speeds. The overall correlation of all angular measurements was 0.99. The overall root mean squared error (RMSE) was 2.72 degrees.
Conclusion
Our system gives an example of how clinical evaluation may be supported by employing a cost-effective unsupervised and unobtrusive monitoring approach based on objective parameters – and with a SD-Card option - applicable in everyday life. It reaches a sound quality and a high degree of correspondence.
Biomed Tech 2012; 57 (Suppl. 1) © 2012 by Walter de Gruyter · Berlin · Boston. DOI 10.1515/bmt-2012-4427
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... Each visit lasted for 45 minutes, where the clinical outcomes were measured and patients performed the protocol given in table I while wearing the e-AR sensor. The protocol builds on the DynaPort R knee test [3], [23] which is a performance based test previously validated with observations by physiotherapists .The protocol was modified to accommodate mobile equipment which could be transported to patients' homes. An Orthopaedic Specialist Registrar or Senior Physiotherapist was present for at least the first two visits to measure clinical outcomes. ...
A progressive improvement in gait following knee arthroplasty surgery can be observed during walking and transitional activities such as sitting/standing. Accurate assessment of such changes traditionally requires the use of a gait lab, which is often impractical, expensive, and labour intensive. Quantifying gait impairment following knee arthroplasty by employing wearable sensors allows for continuous monitoring of recovery. This study employed a recognised protocol of activities both pre-operatively, and at regular intervals up to twenty-four weeks post-total knee arthroplasty. The results suggest that a wearable miniaturised ear-worn sensor is potentially useful in monitoring post-operative recovery, and in identifying patients who fail to improve as expected, thus facilitating early clinical review and intervention.
... Test persons wear several belts around their trunk and legs, while performing 29 sets of tasks related to ADL, such as walking several distances, climbing different stair heights, and picking an lifting objects and always in the same order. The rationale of the DynaPort Ò system has been explained by van den Dikkenberg et al. [36], and validity has been proven [26,27]. Accelerometers generate the DynaPort Ò knee test subscores (locomotion, rise and descend, lift and move, and transfers) and the overall score. ...
Purpose In total knee arthroplasty, tissue-sparing techniques are considered more important, as functional gain could become more advantageous when early mobilization is commenced. The parapatellar approach is most often used, whereas the subvastus approach is a suitable alternative. Presently, it is unknown, according to true objective measurements, which of the two is most advantageous. Methods In this prospective randomized double-blind, short-term trial measurements (KSS, WOMAC, PDI, VAS, ability to perform) were obtained at day 1, day 3, 1 week, 6 weeks, and 3 months. Results The subvastus group (n = 20) showed only significantly less extension lag direct postoperative (P = 0.04) compared with the parapatellar group (n = 20). Other scores were not significantly different. The Dynaport Ò knee test, an objective performance-based tool, could not demonstrate significant differences. A blunt anatomical dissec-tion was carried out in both observational and histological to support findings. A dense innervation of the distal vastus medialis was found. This is at risk employing the subvastus approach. Both approaches harm the suprapatellar bursa. The vastus medialis sheath must be detached distally to open the knee joint. No true separate vastus medialis obli-quus could be identified. Conclusion Comparable to literature, only mild advantage employing the subvastus approach was found, but only early postoperative and not objectively. As this approach is also not suitable in every case, we will continue to use the parapatellar approach.
... Test persons wear several belts around their trunk and legs, while performing 29 sets of tasks related to ADL, such as walking several distances, climbing different stair heights, and picking an lifting objects and always in the same order. The rationale of the DynaPort® system has been explained by van den Dikkenberg et al. [36], and validity has been proven [26, 27]. Accelerometers generate the DynaPort®knee test subscores (locomotion, rise and descend, lift and move, and transfers) and the overall score. ...
In total knee arthroplasty, tissue-sparing techniques are considered more important, as functional gain could become more advantageous when early mobilization is commenced. The parapatellar approach is most often used, whereas the subvastus approach is a suitable alternative. Presently, it is unknown, according to true objective measurements, which of the two is most advantageous.
In this prospective randomized double-blind, short-term trial measurements (KSS, WOMAC, PDI, VAS, ability to perform) were obtained at day 1, day 3, 1 week, 6 weeks, and 3 months.
The subvastus group (n=20) showed only significantly less extension lag direct postoperative (P=0.04) compared with the parapatellar group (n=20). Other scores were not significantly different. The Dynaport®knee test, an objective performance-based tool, could not demonstrate significant differences. A blunt anatomical dissection was carried out in both observational and histological to support findings. A dense innervation of the distal vastus medialis was found. This is at risk employing the subvastus approach. Both approaches harm the suprapatellar bursa. The vastus medialis sheath must be detached distally to open the knee joint. No true separate vastus medialis obliquus could be identified.
Comparable to literature, only mild advantage employing the subvastus approach was found, but only early postoperative and not objectively. As this approach is also not suitable in every case, we will continue to use the parapatellar approach.
Fractures are common orthopaedic problems, and the Ilizarov technique of distraction osteogenesis is becoming a more common way of treating complicated fractures. Mechanical load plays a vital part in the healing of musculoskeletal system. The Ilizarov frame allows the fracture segments to have micro movement within the facture gap and to bear weight on the fractured limb, while the fracture segments are still held relatively stable. The technique and data reported here are part of a larger study of patients being treated with the Ilizarov technique. This study is investigating whether the loading applied to the bone varies between individuals and how this might modulate the healing process. The range of methods used in this study include questionnaires (assessing activity, pain and psychological parameters), radiographs, IRS, and blood sampling. In addition, we have developed an array of displacement transducers, together with an alogarithm to analyse the data, which we intend to use to assess actual loading in the fracture area. The data obtained from the Human Activity Profile (HAP) questionnaire and PAMs will therefore be fitted into this mosaic of techniques, to provide a detailed picture of the inter-relationship of these various aspects of fracture healing in vivo, when the Ilizarov fixator is applied. Monitoring the patient's daily activity will provide vital critical information for research and for clinical diagnosis. Obviously it is very difficult to monitor the fracture patients' routine mobility for a continuous 24 hour period. In this study, we used the Physical Activity Monitor (PAM) to study the patients' continuous ambulatory activity over 24 hours. The Physical Activity Monitor (PAM) is a TriTrac acceleration monitor which can be used to record data for 24 hours. It weighs 55 grams, with dimension of 64x62x13 mm, which allows us to track a patient's daily activities without affecting his normal activity and life pattern. PAM has been used to study Obstructive Pulmonary Disease 1 , Rheumatoid Arthritis 2 , knee problems 3-6 and also chronic disease, back surgery and tumor surgery of the leg. It is presumed that the fracture site will bear some loading during the action period, e.g. walking, stair climbing etc. In order to prevent extraneous movement during use, the PAM is firmly secured to back with a backpack belt. The PAM was taken home by the patient and it is suggested that he switches it on when he feels that he is undertaking normal activities. The very large amount of recorded data obtained was analyzed using Matlab to identify the acting and non-acting duration. This entailed writing a novel program to analyze the mass of data. The HAP is a self-reporting questionnaire. It consists of a list of 94 activities ranked in ascending order of level of energy required to perform each activity. The questionnaire is calculated using the Maximum Activity Score 7 and the Average Activity Score (AAS). MAS gives the maximum activity the patient can still do, while AAS gives a better assessment of the range of activities performed and of the presence of impairment. These scores will be compared with the PAM result to study the patient's activity times in each study period and throughout the fracture healing process. We have previously validated this approach by giving the HAP questionnaire to 12 Ilizarov patients over the distraction period. The data obtained showed that, as healing progressed, the HAP score for an individual increased. We report here on the relationship between the HAP score and actual activity, measured using the PAM. A limb lengthening patient, with 41mm distraction length, was studied for the whole lengthening period of 113 days. The average acting time, as measured by the PAM, was 4277 seconds over a 24 hours period. The AAS was 47, and the correlation coefficient r between the two results was 0.611. This result suggests that the activity as measured by PAM recording and the HAP score have a strong positive correlation, with high-levels of PAM results associated with high-levels of HAP scores. It also found that the patient's time of activity had just slightly increased during the limb lengthening. This could be attributed to less new bone formation during the lengthening phase. We have recently In conclusion, these preliminary data demonstrate that it is feasible in the clinical situation to use both the patient-reported activity (the HAP) and real-time activity measurement techniques (the PAM) for assessing the actual activity of patients treated by the Ilizarov technique.
The purpose of this study was to determine if improvements in knee function after arthroplasty could be practicably measured in the clinical setting using available, validated technology. The tools we assessed included a timed test of common activities, a platform posturography analysis, and a portable gait laboratory device to quantify body segment motion. We measured the function of 25 total knee arthroplasty patients before surgery and at 1, 4, 12, and 24 months after surgery. Assessment of sit-to-stand, walking, stair climbing, lunging, Knee Society Scores, and Oxford Survey Scores were collected at each interval. Patients showed significant improvement in step length, gait speed, symmetry of weight distribution, symmetry of lunging, and speed of stair climbing. Changes in function with long-term follow-up can be precisely measured, making this technology promising for clinical or research applications.
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In general practice, knee complaints (traumatic and nontraumatic) take second place after back pain in the prevalence of musculoskeletal disorders (19/1000 patients per year), mostly presented as knee pain or functional loss of the knee joint. Of these complaints, approximately 20% are traumatic.
In spite of the high prevalence of knee complaints few studies have assessed the
signs, symptoms and prognosis of nontraumatic knee complaints. Especially in general
practice these data are scarcely available.
The aim of this thesis was to provide more knowledge about the course and prognosis
of nontraumatic knee complaints in adults in general practice.
First, the cross-sectional and longitudinal validity of a performance-based assessment of knee function was determined in first-time consulters with nontraumatic knee complaints in general practice (GP). The validity of this test could not be demonstrated. Further, measurement instruments developed and validated in secondary care are therefore not automatically also valid in a primary care setting.
In a systematic review to prognostic factors of progression of knee osteoarthritis (OA) the available evidence was summarized.
After 1 year follow-up, 49% of the patients reported persistent knee complaints. Symptom characteristics were found the strongest predictors of persisting knee complaints at 1-year follow-up. Physical examination had no added value in predicting persistent knee symptoms in general practice. Also the ACR clinical classification criteria of knee OA had no prognostic value for predicting persisting knee complaints or an increase of disability at one year follow-up.
Concerning medical treatment of the general practitioner, medical treatment at baseline partly corresponded with recommendations given in the Guideline of the Dutch College of General Practitioners for nontraumatic knee complaints in adults. Further, in this study group, medical consumption was relatively high during 1-year follow-up.
Finally, the revised Dutch College of General Practitioners guideline for nontraumatic knee problems in adults is presented. This guideline is developed based on the available evidence in medical literature and recommendations for daily practice are provided.
Objective:
The aim of this study was to develop and validate a user friendly performance based knee outcome score for use in active patients undergoing TKA surgery.
Design:
We prospectively studied a cohort of 50 subjects without any knee symptoms, and 50 patients who underwent TKA for osteoarthritis (OA). The patients were assessed pre- and postoperatively. SF-36 and WOMAC were concurrently administered for comparison. Patients completed seven physical tasks of the finalised outcome instrument which were objectively assessed and scored.
Results:
The mean functional score was 31.7 in the normal subjects. The mean functional score improved postoperatively from 10.0 to 17.7 (P < 0.001) in the TKA group. Our results confirm that the performance based score has a high test-retest reliability (intra-class correlation coefficient (ICC) of 0.89), internal consistency (Cronbach's alpha 0.84) and construct validity showing expected correlations with relevant components of the WOMAC and SF-36 scores. The responsiveness as measured by the effect size compared favourably with the same relevant components of the SF-36 and WOMAC.
Conclusions:
Our performance based knee function score is a reliable dimension specific tool to detect change in musculoskeletal function after TKA. It complements existing self-reported outcome tools in facilitating a comprehensive assessment of patients following TKA.
It is becoming increasingly important to evaluate surgical procedures beyond pain relief and implant survival. Patient satisfaction and objective functional assessment is now as relevant. The aim of this study was to establish the functional differences and patient perceptions between unicompartmental knee replacement (UKR) and total knee replacement (TKR). In a prospective study 52 TKR patients were compared to 24 UKR (at preoperative, 3, 6 months and 1 year postoperative). The disease specific KSS and Womac (pain and function subscores), the generic SF36 (pain, function and patient perception subscores) and the Dynaport®Knee Test, a validated performance-based knee test using accelerometers to score function during activities of daily living, was utilized. Preoperative UKR patients had significantly higher KSS function and the Dynaport®Knee Test (P ®Knee Test showed continued improvement and maintained the functional advantage of UKR patients throughout recovery. UKR and TKR patients have different age demographics, indications and perceptions, but clinical outcome scores do not equally capture these differences, especially with regards to function. Postoperative functional benefits of UKR seem to be due mainly to the superior preoperative conditions. Appreciation of recovery with generic, disease specific and functional measurements appears invaluable.
As a result of the increasing demand for total hip arthroplasties (THA) and total knee arthroplasties (TKA), waiting lists are growing. To cope with this problem, many hospitals have introduced short-stay programs; a consequence is increased responsibility of the patient regarding his own rehabilitation. Although it is clear that the success of a total hip or knee arthroplasty not only depends on an effective surgical procedure but also on adequate rehabilitation afterwards, hospitals do not provide additional support after discharge. The scope of the thesis is to influence and evaluate outcome after short-stay total hip and knee arthroplasty. The thesis is based on 5 papers. Three papers are addressing the first objective of the thesis, which is to develop a support program after short-stay total hip and knee arthroplasty and to determine its effectiveness. The development of a theory-driven support program, called the Groningen Orthopedic Exit Strategy (GOES), is described. Aim of the GOES is to improve the rehabilitation of total hip and knee arthroplasty patients after shortened hospital stay. Research is performed into the validation of the GOES. An experimental study was set up. Unfortunately, no differences were seen between the two groups in terms of changes between preoperative and postoperative values on questionnaires (self-efficacy, social support, pain-coping, WOMAC, SF-36, Physical Activity Questionnaire). The third study evaluates the contributions of preoperative and short-term postoperative self-efficacy in predicting long-term outcome after total hip and knee arthroplasty. Short-term postoperative self-efficacy seems a better predictor of long-term outcome after total hip or knee arthroplasty than preoperative self-efficacy. Interventions should therefore focus on enhancing short-term postoperative rather than preoperative self-efficacy. The second objective of the thesis is to assess recovery after total hip or knee arthroplasty not only with self-report measures but also objectively with a relatively novel, ambulatory measuring device, and to compare the performance-based outcome with self-report outcome. Aim of the first study was to describe the spatio-temporal measures of gait recovery after THA, whereby the different aspects of gait function are measured with an ambulatory measuring device in an extensive test protocol, including walking at different speeds while performing an additional cognitive task and while performing an endurance test. It is concluded that assessment of recovery of gait function requires more than only assessment of “normal” walking. Particularly, an analysis of walking at different speeds and walking while performing an additional cognitive task demonstrate different aspects of gait recovery after THA. In the second study the relationship between self-report and performance-based measures of physical functioning after THA was determined at multiple moments. It is concluded that pain and the diminishing pain after surgery appear as explanatory factors in the discrepancy between self-report and performance-based outcome measures.
To assess the prognostic value of the clinical American College of Rheumatism (ACR) classification criteria of knee osteoarthritis (OA) on persisting knee complaints and increase of disability in adult patients with knee pain in general practice after 1-year follow-up.
Patients (aged >35 years) consulting for non-traumatic knee complaints in general practice were enrolled in the study. At baseline and 1-year follow-up knee complaints and function were assessed by questionnaires and a physical examination was performed. The prognostic value of fulfilling the clinical ACR criteria of knee OA at baseline on the outcomes persisting knee complaints and increase of disability was determined.
549 patients were included in the study of which 480 (87.4%) were available for follow-up. The studied population consisted of 236 (49.2%) women with mean age 53.6 [standard deviation (sd) 11.3], mean body mass index (BMI) 27.1 (sd 4.2), 288 (60.0%) patients had payed employment, and 292 (60.8%) patients fulfilled the clinical ACR criteria of knee OA. After 1-year follow-up, 236 (49.2%) patients reported persisting knee complaints, and 84 (17.5%) reported an increase of disability. There was no association of fulfilling the clinical ACR criteria of knee OA at baseline with persisting knee complaints [odds ratio (OR) 1.15; 95% Confidence Interval (CI) 0.80; 1.67] or increase of disability (OR 1.05; 95% CI 0.43; 2.58) at follow-up.
The clinical ACR classification criteria of knee OA have no prognostic value for predicting persisting knee complaints or an increase of disability at 1-year of follow-up in adult patients with non-traumatic knee complaints in GP.
To predict the 1-year outcome of incident nontraumatic knee symptoms in adults presenting in general practice.
Adults age >35 years with nontraumatic knee symptoms (n = 480) were followed for 1 year. At baseline, data on knee symptoms and demographics were collected and a physical examination performed. Knee symptoms were assessed by self-report questionnaires at 3-month intervals. After 1 year the physical examination was repeated. Multivariate prognostic regression models of patient characteristics, symptom characteristics, and physical examination were used to predict persisting knee symptoms after 1 year. Areas under receiving operating characteristic curves (AUCs) were used to determine the predictive value of the model. To assess the added predictive value of symptom characteristics and physical examination, these models were added to the model of patient characteristics. The improvement was expressed as the difference between the 2 AUCs.
In the multivariate prognostic model of patient characteristics, age >60 years, educational level, kinesophobia, and comorbidity of the skeletal system were associated with persistent knee symptoms after 1 year (AUC 0.67). Of the symptom characteristics, history of nontraumatic knee symptoms, bilateral symptoms, and duration of symptoms >3 months were associated (AUC 0.73). For determinants of physical examination, crepitus of passive extension was associated (AUC 0.55). The added value of the symptom characteristics model to the patient characteristics model was 0.09 (AUC 0.76). Physical examination added no further value.
Symptom characteristics are the strongest predictors of persisting knee symptoms at 1-year followup. Physical examination has no added value in predicting persistent knee symptoms in general practice.
To assess the construct validity of the DynaPort KneeTest (KneeTest), which is a performance-based test to assess functioning of patients with knee osteoarthritis (OA). Scores on the KneeTest (KneeScore) were compared with observations of physical therapists of the patients' functional disability. The reliability of these observations was also assessed.
Twelve physical therapists received identical video tapes showing the performance of 33 patients on the KneeTest. Each physical therapist rated the functional disability of each patient, performing the 23 activities of the KneeTest, on 23 Visual Analogue Scales (VAS(activity)). The 23 VAS(activity) scores were averaged into a VAS(average) score. At the end of the test, an overall rating for the general performance of the patient was given on a VAS(overall). Inter-observer Reliability was assessed for the VAS(activity) scores, VAS(average), and the VAS(overall).
Inter-observer reliability of the VAS(average) was higher (ICC 0.85, 95% CI 0.74-0.92) than the VAS(overall) (ICC 0.65, 95% CI 0.51-0.77). The correlation between the KneeScore and the VAS(average), averaged over the 12 physiotherapists, was 0.86.
The construct validity of the KneeTest was supported by the strong correlation with the ratings of the patients' disability by physical therapists. Given these findings and the high test-retest reliability of the KneeTest that was found in our previous study, we conclude that the KneeTest is a valid measure for assessing functioning in orthopedic and physical therapy research in patients with knee-OA before and after total knee replacement. Longitudinal validity has to be evaluated yet.
To provide an overview of prognostic factors of knee osteoarthritis (OA) progression.
We searched Medline and Embase up to December 2003 according to a specified search strategy (keywords for disease, location, and study design). Studies that fulfilled predefined criteria were assessed for methodologic quality. Study characteristics and associations were extracted and the results were summarized according to a best evidence synthesis.
Of the 1,004 studies found, 37 met the inclusion criteria. Methodologic quality was assessed and only high-quality studies were included (n = 36). The best evidence synthesis yielded strong evidence that hyaluronic acid serum levels and generalized OA are predictive for progression of knee OA. Sex, knee pain, radiologic severity, knee injury, quadriceps strength, and regular sport activities were not predictive. Conflicting evidence for associations was found for several factors including body mass index and age. Limited evidence for an association with progression of knee OA was found for several factors, including the alignment (varus/valgus) of the joint. Limited evidence for no association with progression of OA was also found for several factors, including meniscectomy, several markers of bone or cartilage turnover, and the clinical diagnosis of localized OA.
Generalized OA and level of hyaluronic acid seem to be associated with the radiologic progression of knee OA. Knee pain, radiologic severity at baseline, sex, quadriceps strength, knee injury, and regular sport activities seem not to be related. For other factors, the evidence was limited or conflicting.
In literature no reports appear on functional recovery of unicompartmental knee replacement using both subjective and objective methods. Functional aspects are especially of importance, since prosthetic replacement is considered more often in younger patients, who require an optimal knee function for activities such as sports. In a prospective study on 38 patients with a mean age of 62.2 years functional improvement was measured. Using Knee Society Score (KSS) as a clinician based score and the Dynaport Knee Test as a functional test measurements were performed at preoperative, 3 and 6 months, 1 and 2 years, after surgery. The Dynaport Knee Test is an accelerometer-based system that objectively measures functional aspects of gait during various tasks of daily life. It consists of four sub scores. The KSS assesses pain and function. Both scores range from 0 to 100. The mean KSS preoperative was 44.0 and improved significantly to 81.7 at 3 months (P<0.001) and to 87.4 (P=0.025) at 6 months. No significant differences were noted after 6 months. The mean preoperative Dynaport Knee Test score was 35.8 and at 3 months 43.6 (P<0.001), 48.6 at 6 months (P<0.001). No significant differences were noted after 6 months follow-up. Of the Dynaport sub scores, the low demanding tasks Lift and Move and Locomotion, cease to improve beyond 6 months. The high demanding task Transfers only improved up to 3 months. However, the other high demanding tasks Rise and Descend showed improvement beyond 1 year after surgery, since the improvement from 6 months to 2 years was significant (P=0.023). This study has found that functional recovery continues beyond 6 months and even up to 2 years. It seems only more challenging tests can discriminate on improvement beyond a point where questionnaires cease to improve. The use of objective measurement methods is advocated next to the clinician based scores and self reported questionnaires.
The aim of the study was to determine the cross-sectional and longitudinal validity of a performance-based assessment of knee function, DynaPort KneeTest (DPKT), in first-time consulters with nontraumatic knee complaints in general practice.
Patients consulting for nontraumatic knee pain in general practice aged >18 years were enrolled in the study. At baseline and 6-months follow-up knee function was assessed by questionnaires and the DPKT; a physical examination was also performed at baseline. Hypothesis testing assessed the cross-sectional and longitudinal validity of the DPKT.
Eighty-seven patients were included for the DPKT, 86 were available for analysis. The studied population included 44 women (51.2%), the median age was 54 (range 18-81) years. At follow up, 77 patients (89.5%) were available for the DPKT. Only 3 out of 11 (27%) predetermined hypotheses concerning the cross-sectional and longitudinal validity were confirmed. Comparison of the general practice and secondary care population showed a major difference in baseline characteristics, DynaPort Knee Score, internal consistency, and hypotheses confirmation concerning the construct validity.
The validity of the DPKT could not be demonstrated for first-time consulters with nontraumatic knee complaints in general practice. Measurement instruments developed and validated in secondary care are therefore not automatically also valid in primary care setting.
A 36-item short-form (SF-36) was constructed to survey health status in the Medical Outcomes Study. The SF-36 was designed for use in clinical practice and research, health policy evaluations, and general population surveys. The SF-36 includes one multi-item scale that assesses eight health concepts: 1) limitations in physical activities because of health problems; 2) limitations in social activities because of physical or emotional problems; 3) limitations in usual role activities because of physical health problems; 4) bodily pain; 5) general mental health (psychological distress and well-being); 6) limitations in usual role activities because of emotional problems; 7) vitality (energy and fatigue); and 8) general health perceptions. The survey was constructed for self-administration by persons 14 years of age and older, and for administration by a trained interviewer in person or by telephone. The history of the development of the SF-36, the origin of specific items, and the logic underlying their selection are summarized. The content and features of the SF-36 are compared with the 20-item Medical Outcomes Study short-form.
Reliability coefficients often take the form of intraclass correlation coefficients. In this article, guidelines are given for choosing among 6 different forms of the intraclass correlation for reliability studies in which n targets are rated by k judges. Relevant to the choice of the coefficient are the appropriate statistical model for the reliability study and the applications to be made of the reliability results. Confidence intervals for each of the forms are reviewed. (23 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).
A 36-item short-form (SF-36) was constructed to survey health status in the Medical Outcomes Study. The SF-36 was designed for use in clinical practice and research, health policy evaluations, and general population surveys. The SF-36 includes one multi-item scale that assesses eight health concepts: 1) limitations in physical activities because of health problems; 2) limitations in social activities because of physical or emotional problems; 3) limitations in usual role activities because of physical health problems; 4) bodily pain; 5) general mental health (psychological distress and well-being); 6) limitations in usual role activities because of emotional problems; 7) vitality (energy and fatigue); and 8) general health perceptions. The survey was constructed for self-administration by persons 14 years of age and older, and for administration by a trained interviewer in person or by telephone. The history of the development of the SF-36, the origin of specific items, and the logic underlying their selection are summarized. The content and features of the SF-36 are compared with the 20-item Medical Outcomes Study short-form.
Important clinical decisions often hinge on patients' functional status. Previous studies have shown disagreement among sources of ratings of patients' functional status. This study compared patient self-ratings, family member ratings, and physician ratings of patient function to performance-based functional testing criteria.
Five activities of daily living of 73 older patients were studied at admission to a rehabilitation unit following discharge from an acute care community hospital. Data were collected from patients, family members, and physicians and were compared with performance-based function testing.
Patient ratings were significantly more accurate than physician ratings for walking, transferring, and telephoning. Patients were significantly more accurate than family members for rating walking and telephoning, but patients were not significantly more accurate than family members or physicians for rating eating or dressing.
We conclude that decisions about patients' functional level should be based on performance testing. If performance testing is unavailable, patients' own ratings are most accurate, followed by family ratings. Physicians' ratings are least accurate.
High-quality measurements are needed to develop meaningful clinical practice databases to assess the effectiveness of physical therapy. This study determined the reliability, validity, and responsiveness of measurements obtained with five functional tests graded with the newly developed Iowa Level of Assistance Scale.
Eighty-six patients with total hip or knee replacements were tested at various time periods during their hospitalization. Patients were tested for five functional activities by four therapists to establish the reliability and test responsiveness. The Harris Hip Rating Scale was administered to assess the validity of the functional score.
The weighted Kappa statistic supported good intratester (K = .79-.90) and moderate intertester (K = .48-.78) reliability. The correlation between the Harris Hip Rating Scale scores and the total functional scores was high (r = -.86). The total functional score was responsive to 4 days of therapy postoperatively.
The assessment of function using the Iowa Level of Assistance Scale was shown to be highly reliable, valid, and responsive in patients following total hip or knee replacements.
The reproducibility of a performance-based and a self-reported measure of functional status was investigated, as well as the impact of age and cognitive function on the reproducibility.
Of a random sample of 114 men of the 1995 survey of the Zutphen Elderly Study, 105 men (aged 79.9 +/- 4.5 years) participated in a test-retest study. They filled out a questionnaire on disabilities and carried out performance tests twice, in a 2-week interval. Four performance tests were administered (standing balance, walking speed, chair stand, and external shoulder rotation), and a summary performance score was constructed. The number of self-reported disabilities in basic activities of daily living, mobility, and instrumental activities of daily living were assessed. Kappa statistics and Pearson correlation coefficients between test and retest measurements were computed for the total group and stratified by age and cognitive function.
Three performance tests and the summary performance score had fair to good reproducibility (walking speed: Pearsons r = .90, chair stand: r = .82, shoulder rotation: kappa = .49, summary score: kappa = .52). Only the test for standing balance was poorly reproducible (kappa = .29). The self-reported functional status was fairly to good reproducible (kappa = .63, r = .87). Self-reported functional status was significantly less reproducible in very old and cognitively impaired than in younger and nonimpaired individuals.
In the elderly male subjects, performance tests and self-reported disabilities had moderate to good reproducibility, with the exception of the test for standing balance. In very old or cognitively impaired populations, self-reported functional status may have a lower reproducibility.
We present the rationale and design of the DynaPort knee test. The test aims at measuring knee patients' functional abilities in an unobtrusive, user-friendly way. Test persons wear several belts around their trunk and legs. The belts contain accelerometers, the signals of which are stored in a recorder, embedded in one of the belts. The knee test consists of a set of 29 tasks related to activities of daily life ("test items"). Accelerometer signals are analyzed in terms of 30 "movement features" (accelerations, angles, durations, frequencies, and some dimensionless numbers). In data analysis, the beginning and end of each test item is marked by hand; otherwise, analysis is automatic. We compared 140 knee patients with 32 healthy controls and found 541 of the 29 x 30=870 test item x movement feature combinations differed significantly between the two groups. From these 541 combinations the DynaPort knee score is calculated by the weighted averages of movement features per item, then weighted averages of items per cluster (locomotion, rising and descending, transfers, lifting and moving objects), and finally the average of the clusters. In an initial study the test-retest reliability of the knee test proved high, and the test turned out to be sufficiently responsive (0.7 patients' standard deviations improvement after 24 months). However, it remains difficult to interpret the scores in more meaningful terms than merely "better" or "worse." Extensive reliability studies in the future will further assess the validity of the test and provide more insight into the meaning of the scores. The DynaPort knee test may thus become an important instrument for evaluating patients'functional abilities in knee-related clinical practice and research.
Function studies after total knee arthroplasty (TKA) generally use either self-reported instruments or objective quantitative measurements of walking activities, but it is unclear how objective factors influence self-reports. This retrospective multicenter study assessed the impact of objective variables on subjective self-reported functional outcome after TKA in 128 patients at a mean of 41 months after TKA. Self-reported disability was measured by the Western Ontario and McMaster University (WOMAC) scale, and the quality of walking and representative daily activities were determined objectively by the DynaPort knee test. Objective assessment was found to be a poor predictor of WOMAC abnormality, with correlations of 0.343, 0.246, and 0.269 with WOMAC function, stiffness, and pain, respectively. The results of WOMAC are thus strongly influenced by factors other than quantitative parameters of the lower extremity. These findings provide support for including an objective assessment of activities of daily living together with a subjective self-report.
To examine the determinants of the modest correlation between self-report and performance-related measures in patients with osteoarthritis of the hip or knee.
Measures included the Lower Extremity Functional Scale (LEFS), the self paced walk, timed up-and-go, and stair test. Each performance measure consisted of 3 domains: time, pain (visual analog scale), and exertion (Borg scale). Activity specificity was assessed by examining correlations between the LEFS with single activity and multiple activity time scores. Domain specificity was examined by comparing correlations between the LEFS and single and multiple domain scores. The impact of measurement error was considered.
Increasing the number of activity time scores had no effect. Forming a composite performance score based on time, pain, and exertion substantially increased the correlation from 0.44 (composite timed score) to 0.59 (pooled domain and activity score) (P = 0.009).
Performance scores based on time alone appear to inadequately represent the breadth of health concepts associated with functional status.
Cross cultural validity is of vital importance for international comparisons.
To investigate the validity of international Dutch-English comparisons when using the Dutch translation of the Western Ontario and McMaster Universities osteoarthritis index (WOMAC).
The dimensionality, reliability, construct validity, and cross cultural equivalence of the Dutch WOMAC in Dutch and Canadian patients waiting for primary total hip arthroplasty was investigated. Unidimensionality and cross cultural equivalence was quantified by principal component and Rasch analysis. Intratest reliability was quantified with Cronbach's alpha, and test-retest reliability with the intraclass correlation coefficient. Construct validity was quantified by correlating sum scores of the Dutch WOMAC, Arthritis Impact Measurement Scales (Dutch AIMS2), Health Assessment Questionnaire (Dutch HAQ), and Harris Hip Score (Dutch HHS).
The WOMAC was completed by 180 Dutch and 244 English speaking Canadian patients. Unidimensionality of the Dutch WOMAC was confirmed by principal component and Rasch analysis (good fit for 20/22 items). The intratest reliability of the Dutch WOMAC for pain and physical functioning was 0.88 and 0.96, whereas the test-retest reliability was 0.77 and 0.92, respectively. Dutch WOMAC pain sum score correlated 0.69 with Dutch HAQ pain, and 0.39 with Dutch HHS pain. Dutch WOMAC physical functioning sum score correlated 0.46 with Dutch AIMS2 mobility, 0.62 with Dutch AIMS2 walking and bending, 0.67 with Dutch HAQ disability, and 0.49 with Dutch HHS function. Differential item functioning (DIF) was shown for 6/22 Dutch items.
The Dutch WOMAC permits valid international Dutch-English comparisons after correction for DIF.
The terms observer reliability and observer agreement represent different concepts. Reliability coefficients express the ability to differentiate between subjects. Agreement parameters determine whether the same value is achieved if a measurement is repeated. Parameters for reliability are ICCs for measurements on an interval scale. Parameters for agreement are kappa for measurements on a nominal scale, weighted kappa for an ordinal scale, and levels of agreement for measurements on an interval scale.
Assessing observer reliability and agreement is essential for the interpretation of clinical observations in research and medical practice. Moreover, only if the sources of measurement errors are known, can they be anticipated, thereby improving the quality of measurements.
Objective
To discuss the concepts of the minimal clinically important difference (MCID) and the smallest detectable difference (SDD) and to examine their relation to required sample sizes for future studies using concrete data of the condition-specific Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the generic Medical Outcomes Study 36-Item Short Form (SF-36) in patients with osteoarthritis of the lower extremities undergoing a comprehensive inpatient rehabilitation intervention.MethodsSDD and MCID were determined in a prospective study of 122 patients before a comprehensive inpatient rehabilitation intervention and at the 3-month followup. MCID was assessed by the transition method. Required SDD and sample sizes were determined by applying normal approximation and taking into account the calculation of power.ResultsIn the WOMAC sections the SDD and MCID ranged from 0.51 to 1.33 points (scale 0 to 10), and in the SF-36 sections the SDD and MCID ranged from 2.0 to 7.8 points (scale 0 to 100). Both questionnaires showed 2 moderately responsive sections that led to required sample sizes of 40 to 325 per treatment arm for a clinical study with unpaired data or total for paired followup data.Conclusion
In rehabilitation intervention, effects larger than 12% of baseline score (6% of maximal score) can be attained and detected as MCID by the transition method in both the WOMAC and the SF-36. Effects of this size lead to reasonable sample sizes for future studies lying below n = 300. The same holds true for moderately responsive questionnaire sections with effect sizes higher than 0.25. When designing studies, assumed effects below the MCID may be detectable but are clinically meaningless.
Objective
To establish the responsiveness of observational and self-report methods for the assessment of disability in mobility in patients with osteoarthritis (OA).Methods
Data from 186 patients with hip OA or knee OA were used. Data from 1 observational method and 4 self-report methods for the assessment of disability in mobility were collected at week 0 and again 12 weeks later. Using correlations and factor analysis, the relationships among changes in these 5 methods were established.ResultsIntercorrelations between change scores of the self-report methods ranged from 0.12 to 0.34. Correlations between the observational method and the self-report methods ranged from 0.14 to 0.26. In the factor analysis, both the self-report methods and the observational method loaded on the same factor.Conclusion
In a longitudinal design, no evidence for differential responsiveness of observational and self-report methods was obtained. Because of the advantages of questionnaires (they are easier to use, less time-consuming, and less of a burden to subjects), this implies that the use of self-report methods is to be preferred over observational methods. Arthritis Care Res 45:56–61, 2001. © 2001 by the American College of Rheumatology.
Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are now the most common major orthopedic procedures in the world. Outcome research for patients undergoing total joint arthroplasty is now the accepted method of choice for evaluating the results of surgery. This study design incorporates the use of patient-derived data collected from patient self-administered questionnaires that will capture data on the patient's experience of pain, functional disability, and general health status. These questionnaires do not replace traditional measures of clinical endpoints, such as mortality and complication rates, but will be additions to data collection. The patient-derived data allow orthopedic surgeons to assess the impact of total joint arthroplasty on the health status of their patients. The need to collect these data is increasingly necessary with the growing demands on orthopedic surgeons to demonstrate the efficacy of total joint arthroplasty to maintain funding from both public and private funding sources. This article introduces the development of outcome research for patients undergoing total joint arthroplasty.
In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
To determine the accuracy of self-reports of physical functioning by hospitalized elderly.
Comparison of two measures.
Two-hundred forty-seven medical inpatients (mean age 78.7 years) hospitalized at St. Marys Hospital Medical Center, Madison, WI.
Measures of five activities of daily living by self-report and by performance.
The rate of agreement between self-report and performance ADL measures was the lowest in the areas of bathing and dressing where the agreement was 63% and 64%, respectively. When patients reported needing no help in these two tasks, they were measured lower 32% of the time for dressing and 42% for bathing. When patients reported needing help in an activity the agreement rate between patient and occupational therapist varied widely, from only 42% for toileting to 78% for bathing. The two factors which were statistically associated with poor agreement between the two ADL measurements were cognitive impairment (P less than 0.001) and a decline from the pre-hospital level of ADL functioning which had occurred during hospitalization (P less than 0.001).
These data suggest that there may be significant differences between patient assessments and performance-based measurements of ADL functioning in hospitalized elderly at time of discharge. These differences may have implications for the collection of functional measurements for discharge planning or for geriatric research in the hospital environment.
A new total knee rating system has been developed by The Knee Society to provide an up-to-date more stringent evaluation form. The system is subdivided into a knee score that rates only the knee joint itself and a functional score that rates the patient's ability to walk and climb stairs. The dual rating system eliminates the problem of declining knee scores associated with patient infirmity.
Within the context of a double blind randomized controlled parallel trial of 2 nonsteroidal antiinflammatory drugs, we validated WOMAC, a new multidimensional, self-administered health status instrument for patients with osteoarthritis of the hip or knee. The pain, stiffness and physical function subscales fulfil conventional criteria for face, content and construct validity, reliability, responsiveness and relative efficiency. WOMAC is a disease-specific purpose built high performance instrument for evaluative research in osteoarthritis clinical trials.
Gait analysis based on the triaxial electrogoniometric method was carried out on a large group of normals and total knee replacement patients before and after surgery. Analysis of the objective gait variables was performed to compare the pre and postoperative results with that of the normals. Eight most significant gait variables were identified and from which two functional indices were calculated to provide an overall assessment of the reconstructive procedure based on disease type, side of involvement, and prosthetic design. It was found that total knee replacement provides significant functional improvement. Such improvement was more pronounced in certain patients, but its dependence on prosthetic type remained less conclusive. The results also suggested that there is a critical timing for surgery to obtain its maximum benefit. Knee function after joint replacement is a time-related phenomenon and, therefore, the patients must be followed beyond one-year postoperatively to provide more accurate assessment.
It has been suggested that performance measures of functional status have several advantages over self-report measures for both clinical and research purposes, including: greater patient acceptability, interpretability, reproducibility, sensitivity to change, and the focus on actual ability rather than presumed capability. This article challenges this assumed superiority of "objective," "behavioral" measures by directly comparing self-assessments and blindly rated performance assessments on a specific item by task basis, using an identical rating format.
A set of 14 performance tasks, consisting of a range of functional abilities (including simulations of cooking and sweeping), was administered to 99 community-dwelling older adults (aged 60-92) who had previously completed a 50-item instrumental activities of daily living (IADL) questionnaire. A subsample was retested 2 weeks later, and reassessed at 1 year.
Of 182 subjects willing and able to complete the IADL questionnaire, only 99 attempted at least one of the performance tasks. Tasks that took longer to complete were not necessarily associated with a greater number of errors, nor did accuracy ratings correspond well with difficulty ratings. Good correspondence (greater than 80% agreement) between observed and perceived difficulty was found for only one-third of the item/task matchings. Generally, the rater tended to underestimate difficulty relative to subjective assessments.
Relative to questionnaires, performance measures were not found to be psychometrically superior, more acceptable to respondents, easier to administer, or easier to interpret. Neither type of measure by itself distinguishes between motivation and capability, reflects adaptations made in everyday living, or accounts for personal preferences or reasons for difficulty.
This investigation describes the development and validation of a test battery for evaluating physical activity restrictions (PAR) in patients with knee osteoarthritis (OA). The tasks on the final version of the PAR include (a) a 6-min walk; (b) a stair climb; (c) a lifting and carrying task; and (d) getting into and out of a car. Data from patients with knee OA revealed that the four tasks loaded highly on a single unrotated principal component yielding an alpha internal consistency reliability of 0.92. These data suggest that investigators may choose to use an aggregate score and/or responses from individual tasks. Two week test-retest reliabilities for the four tasks were all in excess of 0.85 and there was support for their concurrent and convergent validity. Specifically, performance on the tasks correlated with time on treadmill, difficulty with self-reported ADLs, and ratings of difficulty following the performance of each task. Additional research is needed on the predictive validity of the measure and its sensitivity to change.
Variable definitions of outcome have been used in the past to assess the results after total joint replacement surgery. These differ in their approach to the measurement of outcome but all must be valid (they measure what they are designed to measure), reliable (they consistently produce the same score), and responsive (able to detect changes that may occur during a period). Responsiveness is crucial to distinguish those patients who benefit from a procedure from those who do not, and a more responsive test will theoretically be able to identify more subtle changes in patient status. The responsiveness of 6 different scoring systems was compared. The results are based on a cohort of 71 patients undergoing total knee arthroplasty in a 7-month period. Responsiveness was determined by performing a paired t test among each patient's scores at 0, 3, and 6 months. The size of the resulting t value represented the comparative responsiveness of the 6 tests. The highest value achieved was with the Western Ontario and McMaster Universities osteoarthritis index and the Knee Society clinical rating scale. The worst scores were achieved by Short Form-36 and time trade off, a utility method of measurement. If small differences between groups of patients are to be shown, measures of outcome that are more responsive to patient change should be used.
The Medical Outcomes Trust is a depository and distributor of high-quality, standardized, health outcomes measurement instruments to national and international health communities. Every instrument in the Trust library is reviewed by the Scientific Advisory Committee against a rigorous set of eight attributes. These attributes consist of the following: (1) conceptual and measurement model; (2) reliability; (3) validity; (4) responsiveness; (5) interpretability; (6) respondent and administrative burden; (7) alternative forms; and (8) cultural and language adaptations. In addition to a full description of each attribute, we discuss uses of these criteria beyond evaluation of existing instruments and lessons learned in the first few rounds of instrument review against these criteria.
Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are now the most common major orthopedic procedures in the world. Outcome research for patients undergoing total joint arthroplasty is now the accepted method of choice for evaluating the results of surgery. This study design incorporates the use of patient-derived data collected from patient self-administered questionnaires that will capture data on the patient's experience of pain, functional disability, and general health status. These questionnaires do not replace traditional measures of clinical endpoints, such as mortality and complication rates, but will be additions to data collection. The patient-derived data allow orthopedic surgeons to assess the impact of total joint arthroplasty on the health status of their patients. The need to collect these data is increasingly necessary with the growing demands on orthopedic surgeons to demonstrate the efficacy of total joint arthroplasty to maintain funding from both public and private funding sources. This article introduces the development of outcome research for patients undergoing total joint arthroplasty.
To assess the reliability and validity of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) as an outcome measure in Asian patients with knee or hip osteoarthritis (OA) in Singapore.
The WOMAC was administered twice 7 days apart to 66 consecutive English-speaking Chinese, Malay or Indian inpatients and outpatients with knee or hip OA seen at a tertiary referral centre through a structured interview, which also assessed demographic and other characteristics. Internal consistency was assessed using Cronbach's alpha, reliability using Spearman's correlations, intraclass correlations and repeatability coefficients, and relationships between WOMAC domains and known determinants of function using Spearman's correlations and the Mann-Whitney U-test.
The WOMAC showed good internal consistency (alpha=0.70 to 0.93) and good reliability, with intraclass correlations of 0.83 to 0.90 and mean test-retest score differences of 0.02 to 0.13 points (possible range 4 points). Results of Likert scoring assessment supported the validity of the WOMAC when interpreted in the context of the close association between pain and physical function. Eight of nine a priori hypotheses relating WOMAC Pain and Physical Function scores to known determinants of function were present, supporting construct validity of this scale.
The WOMAC is a valid and reliable outcome measure in Asian patients with OA in Singapore.
The aim of this study was to validate the Knee Society Clinical Rating System (knee and function scores) and to compare its responsiveness with that of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the Medical Outcomes Study Short Form-36 (SF-36).
Patients were recruited as part of a prospective observational study of the outcomes of primary total knee arthroplasty for the treatment of osteoarthritis in four centers in the United States, six centers in the United Kingdom, and two centers in Australia. Independent research assistants at each site collected the Knee Society clinical data. The WOMAC, SF-36, patient satisfaction, and demographic data were obtained with self-administered questionnaires.
A total of 862 eligible patients were recruited, and complete preoperative and twelve-month data were available for 697 (80.9%) of them. The mean age was seventy years (range, thirty-eight to ninety years), and the majority of the patients (58.9%) were women. Low correlations were found among the items of both the knee and the function score at both assessment times. The Knee Society pain and function scores had moderate-to-strong correlations with the corresponding pain and function domains of the WOMAC and SF-36 (r = 0.31 to 0.72). Measurement of the standardized response mean showed the Knee Society knee score to be more responsive (standardized response mean, 2.2) than the WOMAC (standardized response means, 2.0 for pain and 1.4 for function) and the SF-36 (standardized response means, 1.0 for bodily pain and 1.1 for physical functioning). The Knee Society function score was the least responsive measure (standardized response mean, 0.8). Correlation of changes in scores at twelve months with patient reports of satisfaction and improvement in health status showed the WOMAC and SF-36 to be more responsive than the Knee Society scores.
There is a poor correlation among the items of the Knee Society Clinical Rating System, but the rating system has adequate convergent construct validity. The WOMAC and SF-36 are more responsive measures of outcome of total knee arthroplasty. As they are less labor-intensive for researchers to use and as use of these instruments removes observer bias from the study design, they are preferable for knee arthroplasty outcome studies.
To compare the responsiveness of 3 locomotor tests and 2 questionnaires in the early stage after a total knee arthroplasty (TKA) and to determine if the 4 responsiveness statistics ranked the measures similarly.
Longitudinal study.
Rehabilitation institute.
Twenty-five men and 40 women with knee osteoarthritis scheduled for a first TKA.
Not applicable.
Six-minute gait distance, in-laboratory gait speed and stair ascent duration, Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index difficulty subscale, and Medical Outcomes Study Short-Form 36-Item Health Survey role-physical and physical functioning subscale scores. Effect size, standardized response mean, paired t test, and relative efficiency statistics were computed for 3 time intervals: (1) before TKA to 2 months after TKA, (2) 2 to 4 months after TKA, and (3) before TKA to 4 months after TKA.
Responsiveness varied according to tests and intervals considered. For all intervals, the WOMAC difficulty subscale was the most responsive questionnaire and the 6-minute gait test was the most responsive locomotor test. Stair ascent duration was the least responsive measure. Of the responsiveness indices used, only effect size ranked the tests differently.
The 6-minute gait test and the WOMAC difficulty subscale are recommended for outcome assessment during the early recovery period after TKA. Because interpretation guidelines are available and confidence intervals can be calculated for it, the standardized response mean is the most useful statistic.
Functional measures (fast self-paced walk test, stair climb, and timed up and go) and a self-report measure of function (Lower Extremity Activity Profile) were assessed in 1,805 total hip (761) and knee (1044) arthroplasty candidates (1,063 women, 742 men) preoperatively. Women represented 59% of the study subjects and showed greater disability than men (P <or= .001) in the physical performance and self-report measures. Although the hip arthroplasty group perceived greater functional disability and less satisfaction, the impact of osteoarthritis on the hip and knee was similar in terms of walking and stair performance. Overall, there was low-to-moderate correlation between the self-report and physical performance measures (r = .21- .50).
To determine the reliability, minimum detectable change (MDC), and validity of the Get Up and Go (GUG) test.
Repeated-measures test-retest for reliability. Correlational study for validity.
Institutional practice.
Convenience sample of 130 people, 105 with knee osteoarthritis (OA) (80 women; mean age, 62+/-9 y) and 25 healthy controls (21 women; mean age, 57+/-8 y).
Not applicable. Main outcome measures Western Ontario and McMaster Universities Osteoarthritis Index, the Activity of Daily Living Scale of the Knee Outcome Survey, and the 8 scales of the Medical Outcomes Study 36-Item Short-Form Health Survey.
Intratester and intertester reliability was.95 (95% confidence interval [CI],.72-.98) and.98 (95% CI,.94-.99), respectively. The MDC, based on measurements by a single tester and between testers, was 1.5 and 1.2 seconds, respectively. Time to perform the GUG test was longer for persons with knee OA than it was for the controls (mean difference, 3.3s; 95% CI, 1.8-4.9). Correlations between the GUG test and measures of physical function did not differ significantly from correlations between the GUG test and measures that do not specifically evaluate physical function.
The GUG test is reliable and has an MDC that is adequate for clinical use. Validity of the GUG test as a single measure of physical function was not supported. Further research should include testing a battery of performance-based measures of physical function.
To assess and compare the test-retest reliability and the construct validity of the Lequesne and the French-Canadian version of the WOMAC indexes.
Patients with symptomatic knee osteoarthritis (OA) fulfilling the revised criteria of the American College of Rheumatology completed both the Lequesne and the French-Canadian version of the WOMAC indexes twice at a 3-h interval. Impairment outcome measures, patients' perceived discomfort in walking and handicap were recorded. For both questionnaires, an analysis was performed item by item. Repeatability was assessed using the intraclass correlation coefficient (ICC) and the Bland and Altman method. Construct validity was investigated using the Spearman rank correlation coefficient and a factor analysis was performed.
88 patients were included. Eight questions of the WOMAC section C and one question of the Lequesne index had insufficient psychometric properties. Although repeatability of questionnaires was fair to excellent (0.82, 0.68, 0.74, 0.95 for the WOMAC sections A, B, C and Lequesne index respectively), construct validity could not be demonstrated. Factor analysis of the WOMAC extracted five factors which differed from the a priori triple stratification. Factor analysis of the WOMAC section C extracted two factors explaining 71% of the variance which could not be clinically characterized. For the Lequesne index, expected convergent correlations were not always achieved. Three factors were extracted by factor analysis explaining 58% of the variance.
Despite their good test-retest reliability, the two composite indexes evaluated are not valid to assess the concept of functional disability induced by knee OA in a French population.
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- De Vet HC
Second workshop on research methodology; 25–27 June, 2003
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- Terwee CB
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- de Vet HC
Mokkink et al up and go test in patients with knee osteoarthritis
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Evaluating quality-of-life and health status instruments: development of scientific review criteria
- Lohr